Lipids provide energy, support cell structure, and help your body absorb essential vitamins. In food, they also impart flavor, richness, moisture, and a delightful mouthfeel. Alas, all good things come to an end. This sad commentary is especially true for lipids in the food matrix.
- When lipids in the food matrix oxidize, they produce compounds that render the food inedible, leading to waste and huge economic losses.
- Thousands of years ago, humans developed methods to draw water out of meat and fish to prevent bacterial growth and ensure food lasted longer.
- For decades the food industry has used synthetic preservatives to extend the shelf life of food, but consumers are now seeking preservatives made with or inspired by natural products.
- Companies are developing nature-inspired molecules to prevent lipid oxidation and meet clean-label standards.
When lipids begin to oxidize (https://doi.org/10.1186/s40066-017-0130-8), the fatty acids are converted into ammonia and organic acids, like hydroperoxides, epoxides, aldehydes, ketones, and oxidized sterols. These compounds are responsible for the unpleasant sensory changes, like a rancid smell and off taste. The rancidification process also shortens the shelf life of food, leading to food waste and economic losses (https://doi.org/10.1002/ejlt.201900298).
IN THE BEGINNING, THERE WAS SALT AND SMOKE
More than 5000 years ago, humans developed different techniques to extend the use of meat and fish. Some of the earliest preservation methods involved smoking and curing to draw out moisture and prevent microbes from taking hold. Through an iterative approach, epicureans have adjusted the time, humidity, temperature, and spices to impart a unique flavor and texture for each creation. Cured foods gained greater popularity about 2000 years ago as the practice transitioned from a means of survival to gourmet delights, including the still popular charcuterie board.
With the dawn of an industrialized food system, the food industry embraced chemical compounds (https://doi.org/10.3390/antiox9040281), like sodium benzoate, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG) and tertbutylhydroxyquinone (TBHQ), to slow lipid oxidation and prevent the growth of bacteria that can cause illness. While synthetic preservatives are safe at low concentrations and have been used in the food system for decades, consumer voices are growing louder in their demand for natural preservatives.
Companies and food manufacturers are exploring the use of natural, plant-derived or plant-inspired compounds for preservation to meet consumer demands for clean and natural food that remains shelf stable and safe. Simultaneously, the clean label movement (https://cleanlabelproject.org) is growing in popularity. While not formally defined, the label identifies foods made
with natural ingredients so consumers can quickly avoid undesirable and usually artificial ingredients in a product, including synthetic flavors, colors, preservatives, emulsifiers, and other chemicals, like nitrates and nitrites.
“People want food to be fresh, healthy, convenient, and safe without food additives,” said Linda May-Zhang, vice president of innovation at Blue California Ingredients. “Plant-based alternative methods for preservation can serve as a bridge between consumer demand and food preservation.”
POLYPHENOLS TAKE CENTER STAGE
Scientists are mining compounds produced by plants to develop healthier approaches to preservation. More importantly, these new techniques maintain the taste, color, and freshness that any consumer would expect when purchasing their favorite products.
Fruits, vegetables, green tea, and other herbs, like oregano, clove, rosemary, thyme, and sage, produce polyphenols (https://doi.org/10.3390/medicines7050026). These compounds are the first line of defense for plants. Unable to pick up stakes and move to a better locale, polyphenols help plants weather inclement environmental conditions, thwart attacks (https://doi.org/10.3390/foods10102469) from insects and microbes, and incorporate free radicals (https://doi.org/10.1186/1471-2229-5-S1-S23) into their aromatic rings to slow oxidative damage. It is the last two characteristics that have captured the interest of the food industry.
Polyphenols are structurally diverse secondary metabolites that are produced following the shikimate and/or polyketide pathways. These compounds fall into several groups: phenolic acids, coumarins, flavonoids, stilbenes, and lignans. Polyphenols impart aroma and color to food. More importantly, they contain antioxidant properties that can be used as a biopreservative (https://doi.org/10.1016/j.cofs.2021.12.011), by combining with metal ions that microbes need to grow.
ANTIOXIDANT POWER OF ROSEMARY, ONIONS, AND THE LARCH TREE
Blue California (https://bluecal-ingredients.com/) has developed nature-based solutions for clean and sustainable ingredients that can be applied to a wide range of food and beverages. As an alternative to botanical extraction, the company harnesses the power of plant biochemistry to produce and amplify these polyphenol compounds through precision fermentation and enzymatic bioconversion. Following this more sustainable approach, the company uses less water and energy than the botanical extraction processes to make high-purity products with consistent quality. Some compounds are even being explored for their potential human health benefits in clinical trials.
“Synthetic antioxidants and microbial growth inhibitors have been useful food preservatives for decades,” said May-Zhang. “As the food industry moves toward more natural solutions derived from plants, we have positioned our pioneering nature-based preservatives to meet this growing demand.”
The company has created a line of antioxidants that can inhibit lipid oxidation and suppress microbial growth to extend the shelf lives of food and beverages. Rosavel® benefits from rosmarinic acid, a naturally occurring polyphenol in rosemary. This antioxidant has been shown to reduce the formation of oxidation products, similar to the synthetic compound BHT. Unlike many extracts from rosemary, Rosavel® rosmarinic acid lacks the color and odor associated with rosemary, which can impact the formulation of food and drinks. It has been shown to reduce the browning of fruits and baked goods and slow the discoloration in meat. It also provides some antimicrobial activity.
Taxifolin (dihydroquercetin) is an antioxidant found in the polyphenol fraction of onions, apples, and even the larch tree. It has a similar activity as water-soluble vitamin E, like Trolox, α-tocopherol, and synthetic antioxidants, like BHT and BHA. According to Blue California, emerging evidence suggests taxifolin has potential to preserve color and extend the shelf life of foods. The company produces Taxifolin BC-DHQ® by bioconversion processes and is also exploring the health benefits of the product to boost the immune system.
The antioxidant hydroxytyrosol is found in olives and is produced at high purity by fermentation. Hydroxytyrosol protects omega-3 oils from oxidation, with potential applications in meat and edible oil preservation. The European Food Safety Authority (EFSA) has recommended that hydroxytyrosol be consumed for its beneficial effects on human health, including its antioxidant activity. Current clinical trials are evaluating the effect of hydroxytyrosol-fortified olive oil on cardiovascular health.
p-Coumaric acid is a phenolic acid produced by peanuts, tomatoes, carrots, and oats. It is primarily an antimicrobial that is effective against two prominent food pathogens, E. coli and Salmonella aureus, common in poultry, beef, and produce. Blue California has harnessed the power of fermentation to produce highly pure p-coumaric acid in the product branded as OataViaTM. The company is looking for commercial partners interested in testing in their food and beverage matrices.
THE POWER OF ANTIOXIDANTS IN PROCESSED FOODS
Kalsec (https://www.kalsec.com) is also in the plant-based preservation game. The company has incorporated natural antioxidants produced by plants into standard oils that have proven to be a cost-effective approach to replace high oleic varieties while maintaining, or even increasing, the oxidative stability of food.
“Consumers want more natural ingredients that they [can] recognize,” said David Johnson, director of Product Management, Food Protection at Kalsec. “We are taking what nature has evolved over millions of years and [have] applied it to protect food.”
Rosemary is a natural antioxidant. Kalsec has invested in plant breeding and crop selection programs to harness rosemary
compounds in an extract. The company has created Herbalox®, a cold brine-infused with the rosemary extract. It stands as a first line of defense against oxidation. The rosemary compound decays first to preserve the stability of lipid molecules. The company has found Herbalox® to be effective in cooked, cold-storage chicken to prevent spoilage.
Kalsec also combined the power of rosemary extract with additional antioxidants obtained from green tea, acerola, and tocopherols in another product, called Duralox®. The mixture
provides a stronger oxidative protection for food in stressful conditions, like frying and baking. Duralox® targets the double bonds in polyunsaturated fatty acids, which are the most susceptible to breaking down. This is particularly notable in fish oils, but it is also effective in the lipids found in the muscle tissue of meat.
“Duralox® combines multiple antioxidants with a synergistic effect where you get greater stability than from just one of the components,” said Johnson. “It is like one plus one equals three.”
Kalsec studied Herbalox® and Duralox® in canola and sunflower oil and measured the antioxidant level using the Oxidative Stability Index. Both products reduced lipid oxidation compared to untreated oils by at least one day. The company also tested their products on several processed foods. The antioxidant-containing canola oil was sprayed on snack crackers, which delayed oxidation during a highly stressed environment and improved shelf stability. The antioxidant oils were also added through post-production spray tumbling to corn-based puffs, which increased oil stability by about eight weeks and delayed the development of aldehydes, the secondary oxidation compounds responsible for many undesirable aromas and flavors associated with rancid oils.
THE ROAD AHEAD
Companies will continue to search for compounds that can confer both antioxidant and antimicrobial protection and are as effective as the current line of synthetic compounds across a wide spectrum of products. While most people want to avoid chemical names associated with synthetic preservatives, consumers may not be well-versed in the uncommon names of natural preservatives. According to May-Zhang, companies may need to raise awareness of the potential benefits of these compounds with consumer education and outreach campaigns to ensure their adoption in the marketplace.
“We are focused on the next generation of consumers interested in plant-based preservatives, which also make purchasing decisions based on the planet’s well-being and sustainability
goals,” said May-Zhang. “Any hurdles related to lesser-known, nature-based ingredients and those produced by biotechnology will take time, consumer education, and outreach as we bring these ingredients into the marketplace.”
About the Author
Stacy Kish is a science writer for INFORM and other media outlets. She can be contacted at firstname.lastname@example.org