Skip to main content
ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Healthy Processed Foods Research » Research » Research Project #428789

Research Project: Adding Value to Plant-Based Waste Materials through Development of Novel, Healthy Ingredients and Functional Foods

Location: Healthy Processed Foods Research

2020 Annual Report

The overall goal of this research project is to make food production more sustainable by using food processing technologies to add value to the byproducts generated from the harvest of specialty crops and production of processed foods. We will focus on the following three objectives over the next five years: Objective 1: Increase the commercial value of plant-based, postharvest waste materials, high in dietary fiber and/or polyphenols (grape, berries, tomato, carrot, and olive pomace, olive leaves and water, mushroom byproducts), by reprocessing into healthful food ingredients. 1.1: Screen processing wastes for nutritional properties of the whole pomace, seeds, skins, and the extractable and nonextractable (high fiber) fractions using appropriate animal models. 1.2: Increase value by developing healthful ingredients with improved bioaccessibility to bioactive polyphenols by process treatments such as extrusion, thermal, chemical and enzymatic processing of the whole waste. Objective 2: Enable new, commercial functional foods from high protein–based waste materials (nuts, legumes, rice, fish). 2.1: Analyze nutrient content of processed farm waste (soybean, peanut, rice and salmon) for functional properties and nutritional quality of protein fraction. 2.2: Formulate and test high protein gluten free health promoting products for consumer acceptability. Objective 3: Enable value-added commercial applications of nanofibers from specialty crop waste materials to deliver bioactives in new functional foods. Objective 4: Increase the utilization of post-harvest waste materials by identifying and removing astringent and mineral components that detract from taste, quality, nutritional value and consumer acceptance.

Objective 1: Determine if processed food wastes or their components from regional fruit and vegetable food processing have health promoting properties by using animal models of obesity and related metabolic diseases to evaluate bioactivity. Animal models are necessary since many bioactive compounds are not absorbed directly but are mediated by gut bacteria. Some waste materials may require fractionation, for example seeds from peels, in order to concentrate bioactive components to a useful level. Bioavailability and bioactivity of more bioactive compounds such as polyphenolics and plant sterols may be increased by removing and modifying dietary fibers that block accessibility to enzymes and gut bacteria. Bioactive food wastes such as mushrooms with high vitamin D content will be processed into films or coatings. Objective 2: Develop new healthy and flavorful foods from high protein waste materials. Processing wastes from soybeans, peanuts, rice and salmon will be analyzed for protein composition and food related physico-chemical properties. The waste materials will be formulated into foods to increase protein content and improve protein quality. Waste ingredients are often high in insoluble fibers that reduce functionality and may require fractionation from fiber to improve useful properties. Objective 3: Develop blow spinning technology to efficiently produce natural nanofibers for controlled release applications and evaluate potential pulmonary toxicity effects of nanofibers in mice after intratracheal instillation of nanofibers. Using blow spinning processes nanofibers will be created from food ingredients such as gelatin, chitosan, and fruit and vegetable pomaces (grape, carrot, tomato and olive) in order to eliminate or reduce potential inhalation inflammation or toxicity. Although the nanofibers will be used for encapsulation of bioactive compounds for oral delivery the potential for inhalation during process requires toxicity testing. The ingredients as well as the nanofibers will be evaluated for inflammation and toxicity in a mouse model to determine degree and persistence of inflammation or toxicity if any. Ingredients that are most biocompatible will be used in subsequent studies. Objective 4: Develop strategies to mitigate astringency in post-harvest materials in order to increase their utilization. Tannins and minerals contribute to astringency and the identification and characterization of these components is essential. Total and free mineral contents in waste materials (nut shells, hulls, pits, pomaces, skins and seeds from stone fruits, nuts, and persimmons) will be measured using microwave-induced plasma atomic emission spectrometry following microwave-assisted digestion or leaching. Tannin levels in the same materials will be measured using total soluble phenolic, potassium iodate (hydrolysable tannin), and vanillin (condensed tannin) assays. The metal (Zn, Cu, Fe) and protein binding properties of waste material tannins will be measured and compared to the properties of commercially available tannins.

Progress Report
This is the final report for project 2030-41440-007-00D, which has been replaced by project 2030-41440-008-00D, titled, “Prevention of Obesity Related Metabolic Diseases by Bioactive Components of Food Processing Waste Byproducts and Mitigation of Food Allergies”. Research by ARS and others has shown that complex compounds, commonly called secondary metabolites or antioxidants, in the peels of fruits and vegetables, leaves, bark, and some grains are able to prevent chronic metabolic disease conditions associated with obesity. In support of Objective 1, researchers in Albany, California, concentrated on the compounds in wine grape seeds and skins because they contain one of the highest concentrations of these antioxidants. The research at Albany focused on the utilization of the whole waste skins and seed pomace byproducts of the California wine industry, whereas most other research used concentrated extracts. The whole grape pomace is high in dietary fibers as well as bioactive antioxidants, safe for human consumption, and could be used as a food ingredient, whereas extracts are used as dietary supplements. In support of Objective 1, ARS scientists used rodents fed high fat diets as animal models for obesity- related chronic diseases. On high fat diets the animals became obese and had similar adverse health characteristics to humans. The scientists reported that powdered wine grape seed flours reduced body weight gain, blood cholesterol and triglycerides, fatty liver, abdominal fat deposits, and other characteristics linked with metabolic diseases associated with obesity in the animals fed high fat diets. The beneficial effects of wine grape seed flours were associated with significant changes in the numbers and types of gut bacteria. It is widely believed that obesity and related chronic disease are associated with a low-level chronic inflammation derived from the passage of bacterial cell wall fragments into the body. ARS scientists showed that significant amounts of complex polyphenols are found in the feces, suggesting that they reach the colon but are not easily modified by gut bacteria. A greater understanding of the optimum structure that reduces inflammation and adverse metabolic effects of weight gain would more easily enable food producers to incorporate beneficial processing byproducts into healthful foods. In further support of Objective 1, ARS scientists found that antioxidants in apple peels reduced risk factors for chronic disease in an animal model of obesity. Apple pomace is a waste byproduct of apple juice production. Peels from red delicious, yellow delicious, black Arkansas, and extract of apple peels were fed to mice on high fat diets. There was a tendency to lower body and adipose weight with increasing amounts of peels. The gut bacteria were also modified by apple peel feeding. Potato peels (red, gold, and russet) were also tested for their ability to reduce the deleterious effects of obesity. Potato peels are an abundant waste material of French-fried potato production. Potato peels contain a different family of bioactive compounds than those found in grape and apples. Potato peels also reduced body weight and adipose weight in mice fed high fat diets. In support of Objective 2, ARS scientists increased the nutritional and economic value of mushroom stalks, a waste product of fresh mushroom production. Mushroom stalks and caps are high in protein. Ultraviolet-B (UV-B) treatment on white and brown Agaricus bisporus mushroom byproducts increased Vitamin D levels. Chitosan, a form of fiber in the mushroom, was also increased slightly after UV-B treatment. Whole black beans, high in protein and fiber, were also fed to mice on high fat diets. The whole beans lowered very low- and low-density lipoprotein cholesterol. The bean diet also improved insulin sensitivity and reduced blood glucose, suggesting that black beans may help to prevent insulin resistance and diabetes. Leptin, a hormone secreted by fat cells, was also decreased by the whole bean diet. Leptin decreases appetite; however, in obese individuals, blood leptin levels are much higher than in individuals of normal weight, due to decreased sensitivity to leptin. Glucagon, a hormone secreted by the pancreas, was also lowered by the whole bean diet. Glucagon decreases blood glucose and is consistent with lower blood glucose found in this study. Many foods and supplements include probiotic bacteria, which are bacteria associated with good health. In support of Objectives 1 and 2, ARS scientists showed that a heat-inactivated probiotic bacteria was able to reduce body weight gain, reduce fat deposits, and lower blood cholesterol in mice fed high fat diets. This study showed that the mammalian host gut may recognize bacterial components and respond beneficially to components of a probiotic or other commensal bacterium. The benefits of yogurt, kefir, kimchi and other fermented foods may be due to both produced metabolites, such as short chain fatty acids, as well as cellular and extracellular components of bacteria. In further support of Objective 2, ARS scientists evaluated the potential health-promoting properties of the waste byproducts of food processing of two new sources: pomegranate peels from juice processing and grain byproducts of beer processing. Peels are high in fiber and grain products are high in fiber and protein. Hamsters on high fat diets supplemented with powdered pomegranate peels and ethanol extract of peels had higher levels of plasma cholesterol. Pomegranate peels were analyzed for expression of genes involved in cholesterol and fat metabolism in the liver in order to understand the molecular basis for the differences in cholesterol. Through a CRADA with a commercial partner, grain processing byproducts were evaluated in mice fed high fat diets supplemented with 10, 20 and 40% byproducts of beer processing. The mice had decreased weight gain with increasing byproduct content. Increasing the beer byproduct decreased caloric density. Typically, animals will adjust their daily food intake to consume the same amount of calories. Surprisingly, the food intake was similar between 0, 10, 20 and 40% beer byproduct diets, suggesting a satiation effect of the fiber and/or protein content. The grain research was necessary to ensure safety and increase stability in support of commercialization of this new healthy food ingredient. This research was awarded a Small Business Innovation Research (SBIR) grant. ARS scientists developed ingredients for snack foods high in protein. The composition of gluten-free whole grains, buckwheat, quinoa, peanut meal, kale and beets in prepared snacks were determined. The sensory properties of whole grain gluten-free buckwheat, peanut meal and kale snacks were found to be satisfactory to consumers. In another study, the sensory properties of quinoa, peanut meal, and beet snacks were evaluated. Towards Objective 3, ARS researchers investigated solution blow spinning (SBS), a novel technique that uses blown gas to elongate biopolymer solutions into nanofibers for controlled release applications. After evaluating SBS processing conditions for obtaining food-grade nanofibers from animal by-products and zein, the scientists used SBS high-molecular weight fish skin gelatin (HMWFG) nanofibers as carriers for carvacrol and cinnamaldehyde. The two antimicrobial compounds were each loaded at multiple concentrations in SBS nanofibers, which were tested for antibacterial activity against three pathogens (E. coli O157:H7, S. enterica, and L. monocytogenes). Tests were conducted both by diffusion (direct contact between nanofibers and bacterial culture) and by vapor phase (no direct contact, antibacterial action through headspace). All HMWFG nanofibers showed dose-dependent antibacterial activity by both diffusion and vapor release at all concentrations of active ingredients for the three pathogenic bacteria. Cinnamaldehyde was a more potent antibacterial released as vapor than carvacrol. Thus, SBS gelatin nanofibers proved to be effective antibacterial carriers with promising applications in food systems. In support of Objective 4, in collaboration with a visiting scholar from China, ARS scientists evaluated a mixture of food herbs used in Chinese tea. The tea ingredients were fermented by a bacterium isolated from the human gut in order to reduce bitterness and astringency. In mice on high fat diets, the fermented tea reduced body weight but did not affect liver or adipose weights, compared to the high fat control and the unfermented tea. Importantly, both the unfermented and fermented teas improved glucose metabolism, as evidenced by improved glucose tolerance test suggesting that the tea may prevent insulin resistance and diabetes. A manuscript is in progress.

1. Purpurin, a natural plant dye, reduces risk factors for obesity related diseases. Obesity is often accompanied by chronic metabolic diseases such as cardiovascular disease, diabetes, hypertension, fatty liver, neurological diseases, and some cancers. Scientists at the ARS laboratory in Albany, California, investigated the effects of purpurin, a natural plant dye, in cell culture and in mice. In fat cells, purpurin decreased reactive oxygen species and a protein important in energy sensing and energy regulation. In mice, purpurin reduced fat accumulation more than 50%. Purpurin or similar compounds in plants may have potential uses to control obesity and reduce associated chronic disease.

2. Compounds in peels of different varieties of cherry tomato may be sources of bioactive compounds. Low grade chronic inflammation is a risk factor for obesity related chronic diseases. Tomato peels are a waste byproduct of canned tomato processing. Scientists at the ARS laboratory in Albany, California, analyzed the free amino acid, phenolic, flavonoid, ß-carotene, lycopene, and glycoalkaloid content of different varieties of cherry tomatoes. Compounds known to reduce inflammation, such as chlorogenic acid, rutin, and lycopene, were highly variable. The observed variations in bioactive compound levels suggest that tomato growers, food processors, and consumers might be able to select cherry tomato varieties with peels containing the highest amount of the nutrients and biologically active compounds, all of which have been reported to have health benefits.

3. Compounds in melon peels may be sources of antioxidants. Melon peels are a waste byproduct of food processing. ARS researchers in Albany, California, analyzed peels for antioxidants from different varieties of organic (Ambrosia, Cantaloupe, Galia, Goddess, Ham, Honeydew, and Tuscan) and non-organic (Canary, Charentias, Hani Gold, Vine ripened, and Santa Claus) melons. The total phenolic content, or measure of antioxidants, varied 4.3-fold from lowest to highest value. The antioxidative activity ranged from 0.13 (organic Tuscan) to 0.26 (organic Galia). The results suggest that the peel from the Honduran Galia melon, with the highest antioxidative activity, merits further study for potential health benefits.

4. Sorghum brans have anti-obesity and anti-diabetic properties. Obesity is often accompanied by chronic metabolic diseases, such as cardiovascular disease, diabetes, hypertension, fatty liver, neurological diseases, and some cancers. Scientists at the ARS laboratory in Albany, California, in collaboration with Chinese scientists, investigated the effects of bran from white, black and sumac varieties of sorghum in an animal model of obesity. Sorghum bran contain high level of antioxidants similar to those in grapes, cinnamon and chocolate. All varieties lowered body weight about 20% compared to controls. Biomarkers for diabetes, such as insulin and leptin, were lowered in sorghum bran fed animals. These results suggest that sorghum bran consumption may reduce obesity and risk factors for diabetes.

5. Loquat leaf tea decreases weight gain in mice on high fat diets. Obesity is often accompanied by chronic metabolic diseases, such as cardiovascular disease, diabetes, hypertension, fatty liver, neurological diseases, and some cancers. Loquat tea is a beverage commonly used in China to suppress cough. Scientists at the ARS laboratory in Albany, California, in collaboration with Chinese scientists, investigated the effects of loquat leaf tea to reduce obesity. Mice on high fat diets supplemented with loquat had reduced weight gain and levels of leptin, a protein that controls appetite. These results suggest that loquat leaf tea may reduce obesity and risk factors for diabetes.

Review Publications
Kim, H., Seo, K., Yokoyama, W.H. 2020. Chemistry of pterostilbene and its metabolic effects. Journal of Agricultural and Food Chemistry.
Elkahoui, S., Levin, C.E., Bartley, G.E., Yokoyama, W.H., Friedman, M. 2019. Levels of fecal procyanidins and changes in microbiota and metabolism in mice fed high-fat diet supplemented with apple peel. Journal of Agricultural and Food Chemistry. 67(37):10352-10360.
Ganji, S., Singh, H., Friedman, M. 2019. Phenolic content and antioxidant activity of extracts of 12 melon (Cucumis melo) peel powders prepared from commercial melons. Journal of Food Science. 84(7):1943-1948.
Wan, J., Wu, Y., Pham, Q., Yu, L., Chen, M., Boue, S.M., Yokoyama, W.H., Li, B., Wang, T.T. 2019. Effects of rice with different amounts of resistant starch on mice fed a high-fat diet: attenuation of adipose weight gain. Journal of Agricultural and Food Chemistry.
Villanueva-Suarez, M., Mateos-Aparicio, I., Perez-Cozar, M., Yokoyama, W.H., Redondo-Cuenca, A. 2019. Hypolipidemic effects of dietary fibre from an artichoke by-product in Syrian hamsters. Journal of Functional Foods. 56:156-162.
Zhu, L., Olsen, C.W., McHugh, T.H., Friedman, M., Levin, C.E., Jaroni, D., Ravishankar, S. 2020. Edible films containing carvacrol and cinnamaldehyde inactive Escherichia coli O157:H7 on organic leafy greens in sealed plastic bags. Journal of Food Safety. 40(2). Article e12660.
Chen, L., Liang, R., Yokoyama, W.H., Alves, P., Pan, J., Zhong, F. 2020. Effect of the co-existing and excipient oil on the bioaccessibility of ß-carotene loaded oil-free nanoparticles. Food Hydrocolloids. 106. Article 105847.
Chen, L., Yokoyama, W.H., Liang, R., Zhong, F. 2019. Enzymatic degradation and bioaccessibility of protein encapsulated ß-carotene nano-emulsions during in vitro gastro-intestinal digestion. Food Hydrocolloids. 100. Article 105177.
Nam, W., Nam, S., Kim, S., Levin, C.E., Friedman, M. 2019. Anti-adipogenic and anti-obesity activities of purpurin in 3T3-L1 preadipocytes and in mice fed a high-fat diet. BMC Complementary and Alternative Medicine. 19:364.