Category Archives: food

Effective treatment for citrus-destroying disease?

Citrus greening is a worldwide problem. A particularly virulent disease that destroys citrus fruit, it’s a problem that is worsening. Before getting to the research from the University of California at Riverside (UCR), here’s more about the disease and how it’s developing from the UCR Huanglongbing, (HLB, Citrus Greening webpage,

The Situation: Citrus huanglongbing (HLB), previously called citrus greening disease, is one of the most destructive diseases of citrus worldwide.  Originally thought to be caused by a virus, it is now known to be caused by unculturable phloem-limited bacteria.  There are three forms of greening that have been described.  The African form produces symptoms only under cool conditions and is transmitted by the African citrus psyllid Trioza erytreae, while the Asian form prefers warmer conditions and is transmitted by the Asian citrus psyllid Diaphorina citri.  Recently a third American form transmitted by the Asian citrus psyllid was discovered in Brazil.  This American form of the disease apparently originated in China.  In North America, the psyllid vector, Diaphorina citri, of HLB is found in Florida, Louisiana, Georgia, South Carolina, Texas and Hawaii, and recently arrived in Southern California from Mexico. HLB is known to occur in Florida Lousiana, South Carolina, Georgia, Cuba, Belize and the Eastern Yucatan of Mexico.  A federal quarantine restricts all movement of citrus and other plants in the family Rutaceae from Asian Citrus Psyllid or HLB-infested areas into California in order to prevent introduction of the disease.

 Damage:  The HLB bacteria can infect most citrus cultivars, species and hybrids and even some citrus relatives.  Leaves of newly infected trees develop a blotchy mottle appearance.  On chronically infected trees, the leaves are small and exhibit asymmetrical blotchy mottling (in contrast to Zinc deficiency that causes symmetrical blotching).  Fruit from HLB-infected trees are small, lopsided, poorly colored, and contain aborted seeds. The juice from affected fruit is low in soluble solids, high in acids and abnormally bitter.  The fruit retains its green color at the navel end when mature, which is the reason for the common name “citrus greening disease.”  This fruit is of no value because of poor size and quality.  There is no cure for the disease and rapid tree removal is critical for prevention of spread.

Economic Impact: HLB is one of the most devastating diseases of citrus and since its discovery in Florida in 2005, citrus acreage in that state has declined significantly.  If the disease were to establish in California, the nursery industry would be required to move all of their production under screenhouses, pesticide treatments for the vector would be instituted resulting in greatly increased pesticide costs (3-6 treatments per year) and indirect costs due to pesticide-induced disruption of integrated pest management programs for other citrus pests.  A costly eradication program would need to be instituted to remove infected trees in order to protect the citrus industry.

Distribution of HLB: In April 2012, after about a week of testing, the California Department of Food and Agriculture (CDFA) removed a pumelo tree with a lemon graft from Hacienda Heights in Los Angeles County after the tree and an Asian citrus psyllid found on the tree both tested positive for Huanglongbing. In 2005, HLB was also found in Florida and it is now known to occur in Louisiana, Georgia, South Carolina, Cuba, Belze and Eastern Mexico.  Worldwide, HLB is also present in China, eastern and southern Africa, the Indian subcontinent, Mauritius, Reunion, the Saudi Arabian peninsula, and southeast Asia.

Research:  Research is focusing on characterization of the bacteria, development of detection methods, and control of the disease and the psyllid.  To date, control of the disease is based on planting HLB-free citrus germplasm, eradication of infected citrus plants, and control of the vector with systemic insecticides.  Countries with HLB learn to manage the disease so that they can still produce citrus.  In California, the best strategy is to keep this disease out. This goal is supported by both federal and state quarantine regulations and the University of California’s Citrus Clonal Protection Program, which provides a mechanism for the safe introduction of citrus germplasm into California.

A July 7, 2020 news item on phys.org announces what researchers hope can be used commercially as a new treatment for citrus greening disease from researchers University of California at Riverside (UCR), Note: Links have been removed,

UC Riverside scientists have found the first substance capable of controlling Citrus Greening Disease, which has devastated citrus farms in Florida and also threatens California.

The new treatment effectively kills the bacterium causing the disease with a naturally occurring molecule found in wild citrus relatives. This molecule, an antimicrobial peptide, offers numerous advantages over the antibiotics currently used to treat the disease.

UCR geneticist Hailing Jin, who discovered the cure after a five-year search, explained that unlike antibiotic sprays, the peptide is stable even when used outdoors in high heat, easy to manufacture, and safe for humans.

A July 7, 2020 UCR news release (also on EurekAlert) by Jules Bernstein, which originated the news item, provides technical detail and information about plans to commercialize the product,

“This peptide is found in the fruit of Australian finger limes, which can naturally tolerate Citrus Greening bacteria and has been consumed for hundreds of years,” Jin said. “It is much safer to use this natural plant product on agricultural crops than other synthetic chemicals.”

Currently, some growers in Florida are spraying antibiotics and pesticides in an attempt to save trees from the CLas bacterium that causes citrus greening, also known as Huanglongbing or HLB.

“Most antibiotics are temperature sensitive, so their effects are largely reduced when applied in the hot weather,” Jin said. “By contrast, this peptide is stable even when used in 130-degree heat.”

Jin found the peptide by examining plants such as the Australian finger lime known to possess natural tolerance for the bacteria that causes Citrus Greening Disease, and she isolated the genes that contribute to this innate immunity. One of these genes produces the peptide, which she then tested over the course of two years. Improvement was soon visible.

“You can see the bacteria drastically reduced, and the leaves appear healthy again only a few months after treatment,” Jin said.

Because the peptide only needs to be reapplied a few times per year, it is highly cost effective for growers. This peptide can also be developed into a vaccine to protect young healthy plants from infection, as it is able to induce the plant’s innate immunity to the bacteria.

Jin’s peptide can be applied by injection or foliage spray, and it moves systemically through plants and remains stable, which makes the effect of the treatment stronger.

The treatment will be further enhanced with proprietary injection technology made by Invaio Sciences. UC Riverside has entered into an exclusive, worldwide license agreement with Invaio, ensuring this new treatment goes exactly where it’s needed in plants.

“Invaio is enthusiastic to partner with UC Riverside and advance this innovative technology for combating the disease known as Citrus Greening or Huanglongbing,” said Invaio Chief Science Officer Gerardo Ramos. “The prospect of addressing this previously incurable and devastating crop disease, helping agricultural communities and improving the environmental impact of production is exciting and rewarding,” he said. “This is crop protection in harmony with nature.”

The need for an HLB cure is a global problem, but hits especially close to home as California produces 80 percent of all the fresh citrus in the United States, said Brian Suh, director of technology commercialization in UCR’s Office of Technology Partnerships, which helps bring university technology to market for the benefit of society through licenses, partnerships, and startup companies.

“This license to Invaio opens up the opportunity for a product to get to market faster,” Suh said. “Cutting edge research from UCR, like the peptide identified by Dr. Jin, has a tremendous amount of commercial potential and can transform the trajectory of real-world problems with these innovative solutions.”

You can find out more about Invaio Sciences here.

Citrus greening has been featured here before in an April 7, 2015 posting titled, Citrus canker, Florida, and Zinkicide. There doesn’t seem to have been much progress made with this Florida solution for citrus greening. This 2018 document on nano.gov was the most recent I could find, ZinkicideTM- a systemic nano-ZnO based bactericide/fungicide for crop protection by Swadeshmukul Santra.

3D-printed graphene sensors for highly sensitive food freshness detection

I love the opening line (lede). From a June 29, 2020 news item on Nanowerk,

Researchers dipped their new, printed sensors into tuna broth and watched the readings.

It turned out the sensors – printed with high-resolution aerosol jet printers on a flexible polymer film and tuned to test for histamine, an allergen and indicator of spoiled fish and meat – can detect histamine down to 3.41 parts per million.

The U.S. Food and Drug Administration has set histamine guidelines of 50 parts per million in fish, making the sensors more than sensitive enough to track food freshness and safety.

I find using 3D-printing techniques to produce graphene, a 2-d material, intriguing. Apparently, the technique is cheaper and offers an advantage as it allows for greater precision than other techniques (inkjet printing, chemical vapour depostion [CVD], etc.)

Here’s more detail from a June 25, 2020 Iowa State University news release (also on EurekAlert but published June 29, 2020), which originated the news item,

Making the sensor technology possible is graphene, a supermaterial that’s a carbon honeycomb just an atom thick and known for its strength, electrical conductivity, flexibility and biocompatibility. Making graphene practical on a disposable food-safety sensor is a low-cost, aerosol-jet-printing technology that’s precise enough to create the high-resolution electrodes necessary for electrochemical sensors to detect small molecules such as histamine.

“This fine resolution is important,” said Jonathan Claussen, an associate professor of mechanical engineering at Iowa State University and one of the leaders of the research project. “The closer we can print these electrode fingers, in general, the higher the sensitivity of these biosensors.”

Claussen and the other project leaders – Carmen Gomes, an associate professor of mechanical engineering at Iowa State; and Mark Hersam, the Walter P. Murphy Professor of Materials Science and Engineering at Northwestern University in Evanston, Illinois – have recently reported their sensor discovery in a paper published online by the journal 2D Materials. (…)

The paper describes how graphene electrodes were aerosol jet printed on a flexible polymer and then converted to histamine sensors by chemically binding histamine antibodies to the graphene. The antibodies specifically bind histamine molecules.

The histamine blocks electron transfer and increases electrical resistance, Gomes said. That change in resistance can be measured and recorded by the sensor.

“This histamine sensor is not only for fish,” Gomes said. “Bacteria in food produce histamine. So it can be a good indicator of the shelf life of food.”

The researchers believe the concept will work to detect other kinds of molecules, too.

“Beyond the histamine case study presented here, the (aerosol jet printing) and functionalization process can likely be generalized to a diverse range of sensing applications including environmental toxin detection, foodborne pathogen detection, wearable health monitoring, and health diagnostics,” they wrote in their research paper.

For example, by switching the antibodies bonded to the printed sensors, they could detect salmonella bacteria, or cancers or animal diseases such as avian influenza, the researchers wrote.

Claussen, Hersam and other collaborators (…) have demonstrated broader application of the technology by modifying the aerosol-jet-printed sensors to detect cytokines, or markers of inflammation. The sensors, as reported in a recent paper published by ACS Applied Materials & Interfaces, can monitor immune system function in cattle and detect deadly and contagious paratuberculosis at early stages.

Claussen, who has been working with printed graphene for years, said the sensors have another characteristic that makes them very useful: They don’t cost a lot of money and can be scaled up for mass production.

“Any food sensor has to be really cheap,” Gomes said. “You have to test a lot of food samples and you can’t add a lot of cost.”

Claussen and Gomes know something about the food industry and how it tests for food safety. Claussen is chief scientific officer and Gomes is chief research officer for NanoSpy Inc., a startup company based in the Iowa State University Research Park that sells biosensors to food processing companies.

They said the company is in the process of licensing this new histamine and cytokine sensor technology.

It, after all, is what they’re looking for in a commercial sensor. “This,” Claussen said, “is a cheap, scalable, biosensor platform.”

Here’s a link to and a citation for the two papers mentioned in the news release,

Aerosol-jet-printed graphene electrochemical histamine sensors for food safety monitoring by Kshama Parate, Cícero C Pola, Sonal V Rangnekar, Deyny L Mendivelso-Perez, Emily A Smith, Mark C Hersam, Carmen L Gomes and Jonathan C Claussen. 2D Materials, Volume 7, Number 3 DOI https://doi.org/10.1088/2053-1583/ab8919 Published 10 June 2020 • © 2020 IOP Publishing Ltd

Aerosol-Jet-Printed Graphene Immunosensor for Label-Free Cytokine Monitoring in Serum by Kshama Parate, Sonal V. Rangnekar, Dapeng Jing, Deyny L. Mendivelso-Perez, Shaowei Ding, Ethan B. Secor, Emily A. Smith, Jesse M. Hostetter, Mark C. Hersam, and Jonathan C. Claussen. ACS Appl. Mater. Interfaces 2020, 12, 7, 8592–8603 DOI: https://doi.org/10.1021/acsami.9b22183 Publication Date: February 10, 2020 Copyright © 2020 American Chemical Society

Both papers are behind paywalls.

You can find the NanoSpy website here.

Improving bacteria detection with the ‘unboil an egg’ machine

Vortex Fluidic Device (VFD) is the technical name for the more familiarly known ‘unboil an egg machine’ and, these days, it’s being used in research to improve bacteria detection. A June 23, 2020 news item on Nanowerk announces the research (Note: A link has been removed),

The versatility of the Vortex Fluidic Device (VFD), a device that famously unboiled an egg, continues to impress, with the innovative green chemistry device created at Flinders University having more than 100 applications – including the creation of a new non-toxic fluorescent dye that detects bacteria harmful to humans.

Traditional fluorescent dyes to examine bacteria viability are toxic and suffer poor photostability – but using the VFD has enabled the preparation of a new generation of aggregation-induced emission dye (AIE) luminogens using graphene oxide (GO), thanks to collaborative research between Flinders University’s Institute for NanoScale Science and Technology and the Centre for Health Technologies, University of Technology Sydney.

Using the VFD to produce GO/AIE probes with the property of high fluorescence is without precedent – with the new GO/AIE nanoprobe having 1400% brighter high fluorescent performance than AIE luminogen alone (Materials Chemistry Frontiers, “Vortex fluidic enabling and significantly boosting light intensity of graphene oxide with aggregation induced emission luminogen”).

A June 24, 2020 Flinders University [Australia] press release, which originated the news item, delves further into the work,

“It’s crucial to develop highly sensitive ways of detecting bacteria that pose a potential threat to humans at the early stage, so health sectors and governments can be informed promptly, to act quickly and efficiently,” says Flinders University researcher Professor Youhong Tang.

“Our GO/AIE nanoprobe will significantly enhance long-term tracking of bacteria to effectively control hospital infections, as well as developing new and more efficient antibacterial compounds.”

The VFD is a new type of chemical processing tool, capable of instigating chemical reactivity, enabling the controlled processing of materials such as mesoporous silica, and effective in protein folding under continuous flow, which is important in the pharmaceutical industry. It continues to impress researchers for its adaptability in green chemistry innovations.

“Developing such a deep understanding of bacterial viability is important to revise infection control policies and invent effective antibacterial compounds,” says lead author of the research, Dr Javad Tavakoli, a previous researcher from Professor Youhong Tang’s group, and now working at the University of Technology Sydney.

“The beauty of this research was developing a highly bright fluorescence dye based on graphene oxide, which has been well recognised as an effective fluorescence quenching material.”

The type of AIE luminogen was first developed in 2015 to enable long-term monitoring of bacterial viability, however, increasing its brightness to increase sensitivity and efficiency remained a difficult challenge. Previous attempts to produce AIE luminogen with high brightness proved very time-consuming, requires complex chemistry, and involves catalysts rendering their mass production expensive.

By comparison, the Vortex Fluidic Device allows swift and efficient processing beyond batch production and the potential for cost-effective commercialisation.

Increasing the fluorescent property of GO/AIE depends on the concentration of graphene oxide, the rotation speed of the VFD tube, and the water fraction in the compound – so preparing GO/AIE under the shear stress induced by the VFD’s high-speed rotating tube resulted in much brighter probes with significantly enhanced fluorescent intensities.

Here’s a link to and a citation for the paper,

Vortex fluidic enabling and significantly boosting light intensity of graphene oxide with aggregation induced emission luminogen by Javad Tavakoli, Nikita Joseph, Clarence Chuah, Colin L. Raston and Youhong Tang. Mater. Chem. Front., [Materials Chemistry Frontiers] 2020, Advance Article DOI: https://doi.org/10.1039/D0QM00270D First published: 28 May 2020

This paper is behind a paywall.

I first marveled about the VFD (unboil an egg machine) in a March 16, 2016 posting.

Nanoparticles make home refrigeration more accessible

Periodically, academic institutions recycle news about their research. I think it happens when, for one reason or another, a piece of news (somebody was exciting) slips past with little notice. I’m glad this June 1, 2020 news item on phys.org brought this research from South Africa to my attention,

Power consumption of a home refrigerator can be cut by 29% while improving cooling capacity. Researchers replaced widely used but environmentally unfriendly R134a refrigerant with the more energy-efficient R600a dosed with multi-walled carbon nanotube nanoparticles (MWCNT). This drop-in refrigerant replacement can be deployed in the field by trained technicians, says an engineer from the University of Johannesburg.

A May 30, 2020 University of Johannesburg press release on EurekAlert, which originated the news item, provides more details about the research,

This test of nanoparticle-dosed refrigerants is a first of its kind and recently published in Energy Reports, an open-access journal. The results can help make home refrigeration more accessible for low-income families.

R134a is one of the most widely-used refrigerants in domestic and industrial refrigerators. It is safe for many applications because it is not flammable. However, it has high global warming potential, contributing to climate change. It also causes fridges, freezers and air-conditioning equipment to consume a lot of electrical energy. The energy consumption contributes even more to climate change.

Meanwhile, a more energy-efficient refrigerant can result in much lower electricity bills. For vulnerable households, energy security can be improved as a result. Improved energy economy and demand-side management can also benefit planners at power utilities, as cooling accounts for about 40% of energy demand.

Nanoparticles enhance power reduction

Nano eco-friendly refrigerants have been made with water and ethylene glycol. Previous studies showed reduced energy use in nano-refrigeration, where refrigerants were dosed with multi-walled carbon nanotube (MWCNT) nanoparticles. The nanoparticles also resulted in reduced friction and wear on appliance vapour compressors.

But previous research did not test the effects of MWCNT’s on hydro-carbon refrigerants such as R600a.

In a recent study, researchers at the University of Johannesburg tested the drop-in replacement of environmentally-unfriendly refrigerant R134a, in a home refrigerator manufactured to work with 100g R134a.

They replaced R134a with the more energy-efficient refrigerant R600a, dosed with MWCNT nanoparticles.

Reduces electricity use by more than a quarter

The researchers removed the R134a refrigerant and its compressor oil from a household fridge. They used a new refrigerant, R600a, and dosed it with multi-walled carbon nanotubes (MWCNTs). Mineral oil was used as a lubricant. The new mix was fed into the fridge and performance tests were conducted.

They found that the R600a-MWCNT refrigerant resulted in much better performance and cooling capacity for the fridge.

“The fridge cooled faster and had a much lower evaporation temperature of -11 degrees Celsius after 150 minutes. This was lower than the -8 degrees Celsius for R134a. It also exceeded the ISO 8187 standard, which requires -3 degrees Celsius at 180 minutes,” says Dr Daniel Madyira.

Dr Madyira is from the Department of Mechanical Engineering Science at the University of Johannesburg.

“Electricity usage decreased by 29% compared to using R134a. This is a significant energy efficiency gain for refrigerator users, especially for low income earners,” he adds.

To gain these advantages, the choice of MWCNT nanoparticles is critical, he says.

“The MWCNT’s need to have nanometer-scale particle size, which is extremely small. The particles also need to reduce friction and wear, prevent corrosion and clogging, and exhibit very good thermal conductivity,” says Dr Madyira.

Managing flammability

The new refrigerant mix introduces a potential risk though. Unlike R134a, R600a is flammable. On the other hand, it is more energy efficient, and it has a low Global Warming potential. Some refrigerator manufacturers have already adopted production with R600a and these appliances are available in the market.

“To do a safe drop-in replacement, no more than 150g of R600a should be used in a domestic fridge,” says Dr Madyira. “Before the replacement, the fridge used 100g of R134a gas. We replaced that with 50g to 70g of R600a, to stay within safety parameters.”

An untrained person should not attempt this drop-in replacement, says Dr Madyira. Rather, a trained refrigeration technician or technologist should do it.

Replacement procedure

“Mineral oil is used as the compressor oil. This should be mixed with the recommended concentration. A magnetic stirrer and ultrasonicator are needed to agitate and homogenize the ingredients in the mixture. The mixture can then be introduced into the compressor. After that, R600a can be charged into the refrigerator compressor, while taking care to not use more than 150g of the gas,” says Dr Madyira.

A woman’s fridge is her castle [Haven’t seen that kind of reference in many years]

A far more energy-efficient refrigerant, such as the R600a-MWCNT mix, can save consumers a lot of money. Vulnerable households in hot climates in developing countries can benefit even more.

Low income earners in many countries are dependent on home fridges and freezers to safely store bulk food supplies. This greatly reduces the risk of wasting food due to spoilage, or food poisoning due to improperly stored food. These appliances are no longer a luxury but a necessity, says Dr Madyira.

Without fridges, people may be forced to buy food daily in small quantities and at much higher prices. Because daily buying may not be required anymore, travel time and costs for buying food can be much lower as well.

Refrigeration also makes it possible to safely store more diverse food supplies, such as fresh fruit and vegetables. Medicines that require cooling can be stored at home. This can make more balanced diets and nutrition, and better physical health, more accessible for a low-income household.

Grid power still rules for low-income refrigeration

From a sustainability point of view, it can look preferable to run most home fridges and freezers from solar power.

However solar panels, backup batteries, and direct current (DC) fridges are still too expensive for most low-income families in areas served by power utilities.

Energy-efficient, alternating current (AC) fridges running on grid power may be more affordable for most. Further cutting power consumption with R600a-MWCNT refrigerant can bring down costs even more.

Refrigeration for all vs demand-side management

As more low-income households and small businesses switch on grid-powered fridges, freezers and air-conditioning, power demand needs be managed better

In South Africa where the study was conducted, the state-operated power utility faces huge challenges in meeting demand consistently. Long-lasting rolling blackouts, known as load-shedding, have been implemented as a demand-side power management measure.

Shaving off more than a quarter of the power consumption of fridges, freezers and air-conditioning units can free up national power supply for improved energy security.

Here’s a link to and a citation for the paper,

Energy performance evaluation of R600a/MWCNT-nanolubricant as a drop-in replacement for R134a in household refrigerator system by T.O Babarinde, S.A Akinlabi, D.M Madyira. Energy Reports Volume 6, Supplement 2 ([proceedings] The 6th International Conference on Power and Energy Systems Engineering (CPESE 2019), 20–23 September 2019, Okinawa, Japan), February 2020, Pages 639-647 DOI: https://doi.org/10.101/j.egyr.2019.11.132

This paper is open access.

An artificial tongue, gold, and maple syrup

I have always imagined the love of maple syrup to be a universal love. A friend who moved to Canada from somewhere else in the world disillusioned me on that subject. She claims to be unable to grasp why anyone would love maple syrup. Should you recognize yourself in those words you may not find this post all that interesting.

However, maple syrup lovers may find this May 5, 2020 news item on Nanowerk a bit disconcerting,

It’s said that maple syrup is Quebec’s liquid gold. Now scientists at Université de Montréal have found a way to use real gold — in the form of nanoparticles — to quickly find out how the syrup tastes.

The new method — a kind of artificial tongue — is validated in a study published in Analytical Methods (“High-throughput plasmonic tongue using an aggregation assay and nonspecific interactions: classification of taste profiles in maple syrup”), the journal of the Royal Society of Chemistry, in the United Kingdom.

The “tongue” is a colorimetric test that detects changes in colour to show how a sample of maple syrup tastes. The result is visible to the naked eye in a matter of seconds and is useful to producers.

“The artificial tongue is simpler than a human tongue: it can’t distinguish the complex flavour profiles that we can detect,” said UdeM chemistry professor Jean-François Masson, who led the study. “Our device works specifically to detect flavour differences in maple syrup as it’s being produced.”

A chemistry professor at Université de Montréal has developed a new test using gold nanoparticles to establish the flavour profile of maple syrup and help producers evaluate its quality. Courtesy: Université de Montréal

There is more information but the central question as to why anyone would want an artificial tongue for tasting maple syrup is never answered (presumably they want to speed up production and ensure more consistent classification) nor is there much in the way of technical detail in a May 5, 2019 Université de Montréal news release (also on EurekAlert),

1,818 samples tested

The artificial tongue was validated by analyzing 1,818 samples of maple syrup from different regions of Quebec. The syrups that were analyzed represented the various known aromatic profiles and colours of syrup, from golden to dark brown.

“We designed the ‘tongue’ at the request of the Québec Maple Syrup Producers to detect the presence of different flavour profiles,” explained Simon Forest, the study’s first author. “The tool takes into account the product’s olfactory and taste properties.”

Maple syrup has a molecular complexity similar to that of wine. Its taste is delicate, without bitterness, and it has a subtle aroma. During the production process, specialized human tasters are employed to judge which profile each batch fits into.

“The development of the artificial tongue is intended to support the colossal work that is being done in the field to do the first sorting of syrups quickly and classify them according to their qualities,” said Masson.

Red for the best, blue for the rest

The researchers compare the artificial tongue to a pH test for a swimming pool. You simply pour a few drops of syrup into the gold nanoparticle reagent and wait about 10 seconds.

If the result stays in the red spectrum, it has the characteristics of a premium quality syrup, the kind best loved by consumers and sold in grocery stores or exported.

If, on the other hand, the test turns blue, the syrup may have a flavour “defect”, which may be treated as an industrial syrup for use in processing.

“It doesn’t mean the syrup is not good for consumption or that it has a different sugar level,” Masson said of the “blue” type syrup, which the food industry uses as a natural sweetener in other products. “It just may not have the usual desired characteristics, and so can’t be sold directly in bottles to consumers.”

60 categories of taste

Caramelized, woody, green, smoked, salty, burnt — the taste of maple syrup has as many as 60 categories to fit into. Maple syrup is essentially a concentrated sugar solution of 66 per cent sucrose and 33 per cent water; the remaining one per cent of other compounds determines the taste.

Like wine, the taste of maple syrup changes according to a variety of factors, including the harvest period, the region, production and storage methods and, of course, the weather. Too much variation in temperature over a weekend, for instance, can greatly affect the taste profile of the product.

The artificial tongue developed at UdeM could someday be adapted for tasting wine or fruit juice, Masson said, as well as be useful in a number of other agrifood contexts.

Here’s a link to and a citation for the paper,

A high-throughput plasmonic tongue using an aggregation assay and nonspecific interactions: classification of taste profiles in maple syrup by Simon Forest, Trevor Théorêt, Julien Coutu, and Jean-Francois Masson. Anal. Methods, 2020, Advance Article DOI: https://doi.org/10.1039/C9AY01942A First published 05 May 2020

This paper is behind a paywall.

Increased food security with hexanal for younger looking, fresher tasting fruits and vegetables

Also known as an anti-aging agent for your fruit and vegetables, hexanal is an environmentally friendly chemical, which is found naturally. Research has led to a synthesized nanotechnology-enabled product now being commercialized. I’ve been following the story off and on since 2012 (see my ‘India, Sri Lanka, and Canada team up for nanotechnology-enabled food packaging‘ posting). I last wrote about the project in a December 29, 2015 posting.

For some reason, hexanal hit the news hard in 2019 having been preceded by some interest in 2018. What follows is an update and a timeline of sorts.

January 2019: More funding

A January 24,2019 essay (also published on the University of Guelph website on January 29, 2019) by Jayasankar Subramanian and Elizabeth Finnis, both are lead researchers on the the project and professors at the University of Guelph (Canada), provides an overview and an update of the hexanal project (Note: Links have been removed) ,

Fruits like mangoes, bananas, papayas and limes are shipped long distances before they get to your table. Many fruits are delicate, and there may be a long period of time that elapses between when the fruit is picked and its arrival in grocery stores and other markets. They’re often picked before they’re truly ripe in order to increase their shelf life.

Even so, globally, up to 40 per cent of all picked fruit can be lost and this represents billions of dollars. But what if we had the technology to delay fruit’s natural degradation process? This is where hexanal can make a difference.

Fruits like mangoes, bananas, papayas and limes are shipped long distances before they get to your table. Many fruits are delicate, and there may be a long period of time that elapses between when the fruit is picked and its arrival in grocery stores and other markets. They’re often picked before they’re truly ripe in order to increase their shelf life.

Even so, globally, up to 40 per cent of all picked fruit can be lost and this represents billions of dollars. But what if we had the technology to delay fruit’s natural degradation process? This is where hexanal can make a difference.

Hexanal is naturally produced by plants to ward off pests; our research at the University of Guelph has found that when it’s applied externally, hexanal can also slow down the aging process.

Like everything else, fruit ages with time. The shrivelling and rot is triggered by the enzyme phospholipase D (PLD), which causes the eventual collapse of the fruit’s membrane. Essentially, fruit membranes are snug, and function like a brick wall of phospholipid bilayers. Phospholipase D breaks the alignment of the bricks, causing the membrane to crumble. Hexanal acts by reducing and slowing the formation of PLD, which in turn slows the collapse of the fruit’s membrane.

In partnership with agricultural and social science researchers in Canada and five other countries, we have tested nine hexanal technologies. These include a spray formulation that gets applied to fruit when they’re still on trees, post-harvest dips, fruit wraps, stickers and sachets embedded with hexanal.

Our findings have implications for consumers, retailers and, more importantly, farmers. For example, when applied as a pre-harvest spray, hexanal can keep fruit on trees longer and keep it fresher after harvest — up to three weeks longer for mangoes.

Hexanal is naturally produced by all plants and is already found as an additive in some food products. Hexanal is also approved by Health Canada as a flavour formula. Our tests of synthesized hexanal sprays, dips and other technologies showed that there were no negative effects on plants, insects or other animals. In addition, hexanal evaporates within 24 hours, which means there’s no residue left on fruit.

Farmers who participated in hexanal testing in Canada and elsewhere were happy with the product both in terms of its effectiveness and bio-safety.

Currently, hexanal for agricultural use is in the two-year regulatory clearance process in Canada and the U.S. Once the process is complete, hexanal formulations are expected to be available for farmer use and can be accessed through companies with a license for production.

Hexanal slows down the ripening and aging process in fresh produce. Author provided

That’s a stunning difference, eh?

Funding

At about the same time as the Conversation essay by Subramanian and Finnis, the University of Guelph published (on the Council of Ontario Universities website) a January 27, 2019 news release announcing new funds for the project,

A University of Guelph research project that has already improved the livelihoods of small-scale Asian farmers will further expand worldwide, thanks to more than $4.2 million in federal support announced Friday afternoon.

The project involves innovative packaging developed in part by Guelph researchers using nanotechnology to improve the shelf life of mangoes, a major fruit crop in much of the world.

Already, the technology has helped to significantly reduce post-harvest losses in Sri Lanka and India. Poor storage meant that farmers routinely lost up to 40 per cent of their crops, worth upwards of $800 million a year. The new technology has also boosted per-acre revenue.

New funding support from the International Development Research Centre (IDRC) and Foreign Affairs, Trade and Development Canada will allow researchers to broaden this successful initiative to Kenya, Tanzania, and Trinidad and Tobago.

Researchers will also look at other fruit — bananas, grapes, papaya, nectarines and berries — and investigate ways to commercialize the technologies.

… it will also be a main pillar of the Guelph-East Africa Initiative, which U of G established to bring together stakeholders to support research and teaching in food, health, water, education, environment and community.

“This confirms our commitment to improve agriculture in East Africa and around the world.” [said John Livernois, interim vice-president {research} ]

The project involves the use of hexanal, a natural plant product that delays fruit ripening and aging. Guelph plant agriculture professor Gopi Paliyath holds an American patent on the discovery of hexanal as a post-harvest agent. It’s also an FDA-approved food additive.

The project also involves Guelph plant agriculture professors Paliyath and Al Sullivan; Loong-tak Lim from Food Science; and Elizabeth Finnis, Sociology and Anthropology. Foreign research partners are based at Tamil Nadu Agricultural University, India; Industrial Technical Institute, Sri Lanka; University of Nairobi, Kenya; Sokoine University of Agriculture, Tanzania; and the University of [the] West Indies, Trinidad and Tobago.

Prior to more funding: a memorandum of understanding

I’m having to guess as the document about the memorandum of understanding (MOU) to commercialize hexanal is not dated but it seems to have been produced in March 2018. (Canada’s International Development Research Centre ([IDRC] has a webpage about the memorandum but no memorandum that I could find.) I stumbled across this account of the event where the MOU was signed,

Ms. Jennifer Daubeny, Consulate General of Canada, delivered the special address narrating the significance of Canadian fundingin developing nanotechnologies to reduce post-harvest losses that enables food security in Asian Countries. Dr. K. Ramasamy, Vice Chancellor, Tamil Nadu Agricultural University [TNAU], Coimbatore presided over the function and highlighted the role of TNAU in knitting nanotechnology research framework and serving as a torch bearer in the country. He emphasized that the GAC-IDRC Project helped more than 60 students and researchers, developed two technologies, filed patents for two inventions, extensive infrastructure development besides helping more than 12,000 fruit growers in the State of Tamil Nadu. Dr. Jayasankar Subramanian, Professor, University of Guelph, Canada, explained the evolution of the project till reached the stage of technology delivery to benefit farmers. Dr. K.S. Subramanian, NABARD Chair Professor, TNAU, Coimbatore, lead Principal Investigator of the Project for India presented nanotechnologies developed to assist in the entire value chain from the farm to fork. Mr. Arun Nagarajan, President, Tamil Nadu Fruit Growers’ Association, explained that the fruit growers are eager to use the technology to improve their farm income. Mr. Terence Park, Managing Director, Smart Harvest Agri, Canada, [emphasis mine] bestowed interest to take forward the technologies to the farm gate and signed MOU with TNAU for the Commercialization of the Hexanal Formulation. Dr. G.J. Janavi,Professor & Head, Department of Nano Science & Technology, TNAU, Coimbatore welcomed the gathering and Dr. C. Sekar, Dean, Imayam Agricultural College,Turaiyur, and Co-PI of the Project proposed a formal vote of thanks.

The Canadian Consul General Ms. Jennifer Daubeny visited all the exhibits and interacted with students, scholars and researchers besides the NGO partner Myrada. She was very impressed with the technologies developed by TNAU in collaboration with University of Guelph, Canada, and looking forward to support research programs in the near future. More than 200 Scientists and Diplomats from Canada, students, scholars, university officials participated in the event.

Products launch by ITI, Colombo

Two of the project’s technology outputs -hexanal incorporated ITI Bio-wax and the Tree Fresh Formulation spray [emphasis mine] were transferred to Hayleys Agriculture Pvt. Ltd., a reputed Agro Service provider in Sri Lanka. The products were launched on 22ndMarch 2018 at the Taj Samudra Hotel, Colombo. The chief guest at the event was the Hon. Susil Premajayantha, Minister of Science Technology and Research (Min. ST&R). The guest of honour was H.E. David McKinnon, High Commissioner for Canada in Sri Lanka. Others present included the Secretary to the Min. ST&R, The Chairman and Director General, ITI, Mr Rizvi Zaheed, Hayleys Agriculture and his team, the Chairman, National Science Foundation, Sri Lanka, representative of the Chairman Sri Lanka Export Development Board, representatives from the Dialog mobile service provider, the Registrar of Pesticides, representing the Dir. Gen., of Agriculture, President of the Lanka Fruit and Vegetable Producers, Processors and Exporters Association, leading large scale mango, papaya and pineapple growers, several export and fruit processing company representatives, senior officials from the ITI, the multi-disciplinary ITI research team and our partner from CEPA. The press was also well represented and a total of 100 persons were present on this occasion. The Managing Director Hayles, the two PIs’ of the project, the High Commissioner for Canada, The Minister and for ST&R and the Secretary to the Ministry addressed the gathering and the new video clip on the project was viewed. The new products were jointly uncovered for display by the Hon. Minister and H.E., the High Commissioner. Samples of the products were distributed to the President of the Lanka Fruit and Vegetable Producers Processors and Exporters Association and to two leading mango growers. The Project team also took this opportunity to run a presentation on the various stages of the project and related activities, display posters on their research findings and to print and distribute the pamphlets on the same as well as on hexanal, the latter as prepared by our partners from the University of Guelph. The launch ended with a time of fellowship providing a useful opportunity for networking.

A YouTube video about the product launch of hexanal-based Bio-wax and the Tree Fresh Formulation spray (I don’t know if those were the permanent names or if they are specific to Sri Lanka and other countries will adopt other names) helped to establish the date for the MOU. You can find the video here.

Judging from the media stories, the team in India has provided most of the leadership for commercializing hexanal.

Commercialization 2019 and beyond

To sum up, after a memorandum of understanding is signed and some prototype products have been unveiled in India in 2018 then, in early 2019, there’s more funding announced by IDRC to expand the number of countries involved and to continue research into efforts to save other types of produce.

Moving things along is an August 15, 2019 news item on Agropages.com,

Two nano formulations would be commercialized by the Directorate of Agri business development of Tamil Nadu Agricultural University (TNAU) soon.  

Fruity fresh is a liquid nano formulation containing hexanal that keeps fruits and vegetables fresh for more days. The pre-harvest spray of Fruity Fresh extends the shelf life of mango for two weeks on trees and another two weeks under storage conditions by employing post-harvest dip methodology, Dr. A. Lakshmanan, Professor and Head, Department of Nano Science and Technology told a meet on “Linking Nano Stakeholders” held at the University.  

Hexanal has also been successfully encapsulated in polymer matrix either as an electro spun fibre matrix (Nano sticker) or nano-pellets that extends shelf life of fruits by 1-2 weeks during storage and transportation, he said.  

This sticker and pellets technology is highly user friendly and can be placed inside the cartons containing fruits during transport for enhancing the freshness.

According to a November 5, 2019 article by Pearly Neo for foodnavigator-asia.com, there is pricing for four products. Nano Sticker and Nano Pellet each will cost $US 0.028 and the spray, Fruity Fresh, will cost $US 4.23 to $US 5.65 for a one liter bottle diluted in 50 liters of water (for use on approximately five trees) and the Fruity Fresh dipping solution at $US 0.0071per kg.

As far as I’m aware none of these products are available in Canada but there is a website for Smart Harvest Agri, Canada although the name used is a little different. First, there’s the Federal Corporation Information listing for Smart Harvest Agritech Limited. You’ll notice there are two directors,

Amanjit Singh Bains
7685 150B Street
Surrey BC V3S 5P1
Canada

Terence Park
Yongsan CJ Nine Park
Seoul
Korea, Republic of

The company’s Smart Harvest website doesn’t list any products but it does discuss something they call “FRESHXtend technology” for fruits and vegetables.

Final comment

I sometimes hear complaints about government funding and what seems to be a lack of follow through with exciting research work being done in Canada. I hope that in the months to come that this story of an international collaboration, which started with three countries and has now expanded to at least six countries and has led to increased food security with an environmentally friendly material and commercialization of research, gets some attention.

From the few sources I’ve been able to find, it seems India and Sri Lanka are leading the commercialization charge while Canada has contributed to an Asian-led project which has now expanded to include Kenya, Tanzania, and Trinidad and Tobago. Bravo t them all!

Quantum dots as pollen labels: tracking pollinators

Caption: This bee was caught after it visited a flower of which the pollen grains were labelled with quantum dots. Under the microscope one can see where the pollen was placed, and actually determine which insects carry the most pollen from which flower. Credit: Corneile Minnaar

Fascinating, yes? Next, the news and, then, the video about the research,

A February 14, 2019 news item on ScienceDaily announces research from South Africa,

A pollination biologist from Stellenbosch University in South Africa is using quantum dots to track the fate of individual pollen grains. This is breaking new ground in a field of research that has been hampered by the lack of a universal method to track pollen for over a century.

A February 13, 2019 Stellenbosh University press release (also on EurekAlert but published February 14, 2019) by Wiida Fourie-Basson, which originated the news item, expands on the theme,

In an article published in the journal Methods in Ecology and Evolution this week, Dr Corneile Minnaar describes this novel method, which will enable pollination biologists to track the whole pollination process from the first visit by a pollinator to its endpoint – either successfully transferred to another flower’s stigma or lost along the way.

Despite over two hundred years of detailed research on pollination, Minnaar says, researchers do not know for sure where most of the microscopically tiny pollen grains actually land up once they leave flowers: “Plants produce massive amounts of pollen, but it looks like more than 90% of it never reaches stigmas. For the tiny fraction of pollen grains that make their way to stigmas, the journey is often unclear–which pollinators transferred the grains and from where?”

Starting in 2015, Minnaar decided to tread where many others have thus far failed, and took up the challenge through his PhD research in the Department of Botany and Zoology at Stellenbosch University (SU).

“Most plant species on earth are reliant on insects for pollination, including more than 30% of the food crops we eat. With insects facing rapid global decline, it is crucial that we understand which insects are important pollinators of different plants–this starts with tracking pollen,” he explains.

He came upon the idea for a pollen-tracking method after reading an article on the use of quantum dots to track cancer cells in rats (https://doi.org/10.1038/nbt994). Quantum dots are semiconductor nanocrystals that are so small, they behave like artificial atoms. When exposed to UV light, they emit extremely bright light in a range of possible colours. In the case of pollen grains, he figured out that quantum dots with “fat-loving” (lipophilic) ligands would theoretically stick to the fatty outer layer of pollen grains, called pollenkitt, and the glowing colours of the quantum dots can then be used to uniquely “label” pollen grains to see where they end up.

The next step was to find a cost-effective way to view the fluorescing pollen grains under a field dissection microscope. At that stage Minnaar was still using a toy pen from a family restaurant with a little UV LED light that he borrowed from one of his professors.
“I decided to design a fluorescence box that can fit under a dissection microscope. And, because I wanted people to use this method, I designed a box that can easily be 3D-printed at a cost of about R5,000, including the required electronic components.” (view video at https://youtu.be/YHs925F13t0

[or you can scroll down to the bottom of this post]

So far, the method and excitation box have proven itself as an easy and relatively inexpensive method to track individual pollen grains: “I’ve done studies where I caught the insects after they have visited the plant with quantum-dot labelled anthers, and you can see where the pollen is placed, and which insects actually carry more or less pollen.”
But the post-labelling part of the work still requires hours and hours of painstaking counting and checking: “I think I’ve probably counted more than a hundred thousand pollen grains these last three years,” he laughs.

As a postdoctoral fellow in the research group of Prof Bruce Anderson in the Department of Botany and Zoology at Stellenbosch University, Minnaar will continue to use the method to investigate the many unanswered questions in this field.

Here’s a link to and a citation for the paper,

Using quantum dots as pollen labels to track the fates of individual pollen grains by Corneile Minnaar and Bruce Anderson. Methods in Ecology and Evolution DOI: https://doi.org/10.1111/2041-210X.13155 First published: 25 January 2019

This paper is behind a paywall.

Here is the video,

Food nanoparticles and their effect on intestinal flora (i.e., your gut microbiome)

This work from Germany is largely speculative. The scientists seem to be interested in exploring how engineered nanoparticles and naturally occurring nanoparticles in food affect your gut. From a January 29, 2019 news item on ScienceDaily,

The intestinal microbiome is not only key for food processing but an accepted codeterminant for various diseases. Researchers led by the University Medical Center of Johannes Gutenberg University Mainz (JGU) identified effects of nanoparticles on intestinal microorganisms. The ultra-small particles adhere to intestinal microorganisms, thereby affecting their life cycle as well as cross talk with the host. One of the researchers’ observations was that nanoparticles’ binding inhibits the infection with Helicobacter pylori, a pathogen implicated in gastric cancer. The findings will stimulate further epidemiological studies and pave the way for the development of potential ‘probiotic’ nanoparticles for food. The discoveries were published in Science of Food.

A January 29, 2019 Johannes Gutenberg University Mainz (JGU) press release (also on EurekAlert), which originated the news item, provides more detail,

Due to their minute size, nanoparticles have unique characteristics and capabilities, such as adhering to microstructures. Nanotechnology is as an important driver of innovation for both consumer industry and medicine. In medicine, the focus is on improving diagnostics and therapeutics, while industry addresses mainly product optimization. Hence, synthetic nanoparticles are already used as additives to improve the characteristics of food. But how can we use nanotechnology more efficiently and safely in food? And are there unknown effects of nanoparticles, which need to be further exploited?

Nutrition strongly influences the diversity and composition of our microbiome. ‘Microbiome’ describes all colonizing microorganisms present in a human being, in particular, all the bacteria in the gut. In other words, your microbiome includes your intestinal flora as well as the microorganisms that colonize your skin, mouth, and nasal cavity.

Scientists and clinicians are interested in microbiomes because of their positive or negative effects on the host. These include modulation of our immune system, metabolism, vascular aging, cerebral functioning, and our hormonal system. The composition of the microbiome seems to play an important role for the development of various disorders, such as cardiovascular diseases, cancer, allergies, obesity, and even mental disorders. “Hence, nutrition and its containing nanoparticulates may affect the microbiome-host balance, finally influencing human health. In order to reduce potential risks and, ideally, promote health, the impact of dietary nanoparticles needs to be understood,” emphasized Professor David J. McClements from the Department of Food Science at the University of Massachusetts in Amherst, USA.

“Prior to our studies, nobody really looked whether and how nano-additives directly influence the gastrointestinal flora,” commented Professor Roland Stauber of the Department of Otolaryngology, Head, and Neck Surgery at the Mainz University Medical Center. “Hence, we studied at a wide range of technical nanoparticles with clearly defined properties in order to mimic what happens to currently used or potential future nanosized food additives. By simulating the journey of particles through the different environments of the digestive tract in the laboratory, we found that the all tested nanomaterials were indeed able to bind to bacteria.” explained Stauber.

The scientists discovered that these binding processes can have different outcomes. On the one hand, nanoparticle-bound microorganisms were less efficiently recognized by the immune system, which may lead to increased inflammatory responses. On the other hand, ‘nano-food’ showed beneficial effects. In cell culture models, silica nanoparticles inhibited the infectivity of Helicobacter pylori, which is considered to be one of the main agents involved in gastric cancer.

‘It was puzzling that we were able to also isolate naturally occurring nanoparticles from food, like beer, which showed similar effects. Nanoparticles in our daily food are not just those added deliberately but can also be generated naturally during preparation. Nanoparticulates are already omnipresent,” concluded Stauber.

The insights of the study will allow to derive strategies for developing and utilizing synthetic or natural nanoparticles to modulate the microbiome as beneficial ingredients in functional foods. “The challenge is to identify nanoparticles that fit the desired purpose, perhaps even as probiotic food supplements in the future. Challenge accepted,” emphasized Stauber and his team.

Here’s a link to and a citation for the paper,

Nanosized food additives impact beneficial and pathogenic bacteria in the human gut: a simulated gastrointestinal study by Svenja Siemer, Angelina Hahlbrock, Cecilia Vallet, David Julian McClements, Jan Balszuweit, Jens Voskuhl, Dominic Docter, Silja Wessler, Shirley K. Knauer, Dana Westmeier, & Roland H. Stauber. npj Science of Foodvolume 2, Article number: 22 (2018) DOI: https://doi.org/10.1038/s41538-018-0030-8 Published 04 December 2018

This paper is open access.

Cellulose and natural nanofibres

Specifically, the researchers are describing these as cellulose nanofibrils. On the left of the image, the seed look mores like an egg waiting to be fried for breakfast but the image on the right is definitely fibrous-looking,

Through contact with water, the seed of Neopallasia pectinata from the family of composite plants forms a slimy sheath. The white cellulose fibres anchor it to the seed surface. Courtesy: Kiel University (CAU)

A December 18, 2018 news item on Nanowerk describes the research into seeds and cellulose,

The seeds of some plants such as basil, watercress or plantain form a mucous envelope as soon as they come into contact with water. This cover consists of cellulose in particular, which is an important structural component of the primary cell wall of green plants, and swelling pectins, plant polysaccharides.

In order to be able to investigate its physical properties, a research team from the Zoological Institute at Kiel University (CAU) used a special drying method, which gently removes the water from the cellulosic mucous sheath. The team discovered that this method can produce extremely strong nanofibres from natural cellulose. In future, they could be especially interesting for applications in biomedicine.

A December 18, 2018 Kiel University press release, which originated the news item, offers further details about the work,

Thanks to their slippery mucous sheath, seeds can slide through the digestive tract of birds undigested. They are excreted unharmed, and can be dispersed in this way. It is presumed that the mucous layer provides protection. “In order to find out more about the function of the mucilage, we first wanted to study the structure and the physical properties of this seed envelope material,” said Zoology Professor Stanislav N. Gorb, head of the “Functional Morphology and Biomechanics” working group at the CAU. In doing so they discovered that its properties depend on the alignment of the fibres that anchor them to the seed surface

Diverse properties: From slippery to sticky

The pectins in the shell of the seeds can absorb a large quantity of water, and thus form a gel-like capsule around the seed in a few minutes. It is anchored firmly to the surface of the seed by fine cellulose fibres with a diameter of just up to 100 nanometres, similar to the microscopic adhesive elements on the surface of highly-adhesive gecko feet. So in a sense, the fibres form the stabilising backbone of the mucous sheath.

The properties of the mucous change, depending on the water concentration. “The mucous actually makes the seeds very slippery. However, if we reduce the water content, it becomes sticky and begins to stick,” said Stanislav Gorb, summarising a result from previous studies together with Dr Agnieszka Kreitschitz. The adhesive strength is also increased by the forces acting between the individual vertically-arranged nanofibres of the seed and the adhesive surface.

Specially dried

In order to be able to investigate the mucous sheath under a scanning electron microscope, the Kiel research team used a particularly gentle method, so-called critical-point drying (CPD). They dehydrated the mucous sheath of various seeds step-by-step with liquid carbon dioxide – instead of the normal method using ethanol. The advantage of this method is that evaporation of liquid carbon dioxide can be controlled under certain pressure and temperature conditions, without surface tension developing within the sheath. As a result, the research team was able to precisely remove water from the mucous, without drying out the surface of the sheath and thereby destroying the original cell structure. Through the highly-precise drying, the structural arrangement of the individual cellulose fibres remained intact.

Almost as strongly-adhesive as carbon nanotubes

The research team tested the dried cellulose fibres regarding their friction and adhesion properties, and compared them with those of synthetically-produced carbon nanotubes. Due to their outstanding properties, such as their tensile strength, electrical conductivity or their friction, these microscopic structures are interesting for numerous industrial applications of the future.

“Our tests showed that the frictional and adhesive forces of the cellulose fibres are almost as strong as with vertically-arranged carbon nanotubes,” said Dr Clemens Schaber, first author of the study. The structural dimensions of the cellulose nanofibers are similar to the vertically aligned carbon nanotubes. Through the special drying method, they can also vary the adhesive strength in a targeted manner. In Gorb’s working group, the zoologist and biomechanic examines the functioning of biological nanofibres, and the potential to imitate them with technical means. “As a natural raw material, cellulose fibres have distinct advantages over carbon nanotubes, whose health effects have not yet been fully investigated,” continued Schaber. Nanocellulose is primarily found in biodegradable polymer composites, which are used in biomedicine, cosmetics or the food industry.

Here’s a link to and a citation for the paper,

Friction-Active Surfaces Based on Free-Standing Anchored Cellulose Nanofibrils by Clemens F. Schaber, Agnieszka Kreitschitz, and Stanislav N. Gorb. ACS Appl. Mater. Interfaces, 2018, 10 (43), pp 37566–37574 DOI: 10.1021/acsami.8b05972 Publication Date (Web): September 19, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.