A vegan way to stop damage from excessive ice build-up and freezer burn
Almost everyone has a bag of veggies shoved into the dark recesses of their freezer that’s now essentially an unrecognizable block of ice crystals. And when thawed, foods damaged by excessive ice lose their texture and become mushy. Now, researchers reporting in ACS’ Journal of Agricultural and Food Chemistry have shown that broken-down soy proteins can prevent ice crystal growth and could be especially useful for preserving frozen vegan foods or biological samples.
Some animals that live in extremely cold environments, such as fish in the deep polar oceans, make antifreeze proteins to keep the liquid in their bodies from freezing. These proteins slow down ice crystal formation and growth, a process that has piqued the interest of the frozen food industry. Recently, researchers discovered that some peptides, which are pieces of broken-down proteins, can also slow ice crystal growth. However, all of the edible peptides tested so far have come from animal sources, including fish, pigs, chickens and cows. So, Tong Wang, Madison Fomich and colleagues at the University of Tennessee wanted to see if breaking down plant proteins could generate similar compounds with ice-crystal-inhibiting properties.
The team generated peptides from a commercially available soy protein isolate powder by exposing it to three different hydrolyzing enzymes: alcalase, pancreatin and trypsin. Each resulting mixture of peptides was also separated by size into multiple fractions.
All of the mixtures slowed ice growth in tests, but the ones produced from alcalase and trypsin were better inhibitors than those from pancreatin. For all three enzymes, most of the activity came from the fraction with the largest peptides. The large-size fractions also ended up including some smaller peptides, which on their own didn’t keep ice crystals from growing; however, the team showed that these small compounds boosted the activity. This study is an initial step toward using soy-derived peptides as a natural, effective way to reduce the ice growth that can lead to freezer burn and thereby increase the shelf life of frozen goods, including vegan and vegetarian products, the researchers say.
The authors acknowledge funding from the U.S. National Science Foundation and the Hatch/Multistate Project through the U.S. Department of Agriculture.
The paper’s abstract will be available on July 19 at 8 a.m. Eastern time here: http://pubs.acs.org/doi/abs/10.1021/acs.jafc.2c08701
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JOURNAL
Journal of Agricultural and Food Chemistry
ARTICLE TITLE
Ice Recrystallization Inhibition Activity of Soy Protein Hydrolysates
ARTICLE PUBLICATION DATE
19-Jul-2023
Melatonin doesn’t just help you sleep — it can help keep fruit and vegetables fresh
The natural compound can be used to reduce the amount of fresh horticultural produce lost due to ‘chilling injury’.
Peer-Reviewed PublicationEdith Cowan University (ECU) horticultural scientists have been compiling research over the past year from all over the world to assess the benefits of melatonin application onto fruit and vegetables, to help keep these highly perishable foods fresher – for longer.
Lead researcher Professor Zora Singh said up to 44 percent of fresh horticultural produce is lost from farm to consumption, and ‘chilling injury’ plays a key role in the postharvest losses.
“You will often see abnormal ripening, sunken spots, pitting, hardening of flesh and browning of peel and pulp in cold-stored fruits, while browning of tissues, translucency and water-soaked lesions in the vegetables, that is what we call chilling injury,” Professor Singh explained.
“The average storage temperature for subtropical fruits and vegetables usually range from 4–8°C while 10–20°C is optimum temperature to avoid chilling injury in tropical horticultural produce.”
Professor Singh and his team claim most of the evidence points to melatonin as one of the best ways to prevent or reduce the effects of chilling injury to cold-stored fruit and vegetables.
“Melatonin is a natural sleeping hormone in living organisms, and it is also helpful in reducing chilling injury symptoms and membrane leakage by maintaining higher levels of antioxidants and freshness of horticultural produce,” researcher and PhD student Shoaib Shah explained.
“Melatonin is a safe alternative to hazardous chemical treatments, without any adverse effects on the consumer health.”
Global food security – the challenge
Across the globe food security is an escalating problem, with food losses rising annually.
- 13.2 per cent of food, valued at $400 billion, is lost annually between harvest and the retail market (FAO 2019)
- 17 per cent of food production is wasted in households, food services and in retail (UNEP 2020)
- Food loss and waste account for approximately 8-10 per cent of global greenhouse gas (GHG) emissions (UNEP 2021)
Fresh produce, such a fruit production is declining, the result of shrinking agricultural land, reduced availability of water supplies, climate change and soil degradation.
Chilling injury is another significant factor contributing to that decline, resulting in 44 per cent of fruit and vegetables not being fit for human consumption globally.
Tropical and sub-tropical fruits are most at risk, as they are highly perishable.
While fruits such as apples can stored for up to nine months, berries can only be kept refrigerated for seven to 12 days.
“When it comes to grains and other produce for harvest, they are more resilient than fresh horticultural produce,” Professor Singh said.
“Fruit and vegetables are not only challenging to grow, preserving them is immensely difficult and this is a crisis affecting nations all over the world, so we need to find the solution to keep producing food from the earth in a sustainable way.”
Professor Zora Singh is a Foundation Professor of Horticultural Science in ECU’s School of Science with global research expertise in production technology and postharvest physiology of horticultural crops.
Presently, Professor Singh and his research team, including PhD students, are working to minimise the global food and nutritional security challenges by improving production technology and reducing postharvest losses in fresh horticultural produce - from farm to fork.
You can read the full paper, Insight into the Role of Melatonin in Mitigating Chilling Injury and Maintaining the Quality of Cold-Stored Fruits and Vegetables authored by Shoaib Shah, Zora Singh, Eben Afrifa-Yamoah, Mahmood UI Hasan, Jashanpreet Kaur and Professor Andrew Woodward here.
JOURNAL
Food Reviews International
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Insight into the Role of Melatonin in Mitigating Chilling Injury and Maintaining the Quality of Cold-Stored Fruits and Vegetables
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