Location: Healthy Processed Foods Research2016 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.
During FY2016 the composition of different structurally related bioactive polyphenols in wine grape seed and skins, a commercial grape seed extract, apple peels and whole apples, a commercial apple extract and potato skins were analyzed. Previously we had shown that powdered wine grape seed flours reduced body weight gain, blood cholesterol and triglycerides, fatty liver, abdominal fat deposits, and other characteristics associated with metabolic diseases associated with obesity in animal models fed with high fat diets. We also showed that the beneficial effects of wine grape seed flours were associated with significant changes in the numbers and types of gut bacteria. In recent years inflammation has been recognized as the cause of metabolic diseases and even obesity. The simplest forms of wine grape polyphenols are absorbed directly into the body but most are too large and complex and travel to the colon where they are metabolized by gut bacteria and modify the population of gut bacteria. Thus it is important to understand the composition of these structurally related bioactive compounds. We also showed that a significant amount of complex polyphenols are found in the feces suggesting that they 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 enable food producers to incorporate beneficial processing byproducts into healthful foods. High protein, waste peanut meal was incorporated into high protein ancient grain gluten free snacks and sensory evaluations were performed. Composition analysis of peanut meal is being completed. Research on optimization of ultraviolet-B (UV-B) treatment on white and brown Agaricus bisporus mushroom byproducts was completed. Higher Vitamin D levels were found in UV-B treated stalks of brown A. bisporus than white. The chitosan yield increased slightly after UV-B treatment and the UV-B treatment had no significant effect on the degree of chitosan deacethylation. In addition novel methods were developed to blow spin nanofibers from corn zein and fish gelatin, both protein sources derived from waste materials. Finally a new collaborative project focused on stabilization and adding value to brewers spent grains was initiated.
1. Bioavailability and metabolism of bioactive polyphenols in wine grape processing wastes. ARS researchers in Albany, California have shown for the first time that obese mice fed with whole grape seed flour had lower weight gain and improved blood lipids and that these physiological changes were associated with changes in certain species of gut bacteria. Most of the beneficial effects of grape seed are due to components called polyphenols. A large fraction of polyphenols are bound to fiber in whole grape seed flours. Feces for free and bound polyphenols were analyzed and it was found that both are metabolized by gut bacteria, however, there were large individual variations. These results suggest that polyphenols associated with fiber and fiber itself are important to the diversity of gut bacteria.
2. Bioavailability and metabolism of bioactive polyphenols in apple juice processing wastes. Polyphenols are bioactive compounds that may prevent weight gain and chronic disease. In apples most polyphenols reside in the skin. Apple polyphenols have shown beneficial physiological activity but the mechanism is unclear. Most free and bound polyphenols pass into the colon where they affect the numbers and types of gut bacteria. ARS scientists in Albany, California determined the amounts of free and bound polyphenols in apple skin byproducts, the types of unabsorbable polyphenols, and the amounts of unabsorbable polyphenols that were found in feces of mice fed wine grape byproducts. They found for the first time that apple polyphenols alter the numbers and types of bacteria in the gut and may be responsible for the beneficial effects of apple consumption.
3. Safety and healthful properties of potato skins. Potato skins, a byproduct of French fry production, are mainly used as feed. The skins are nutritious and contain 12-17% protein, 16-22% dietary fiber, and are low in fat. However, potato skins have a potential to contain toxic alkaloids. Mice fed with diets containing potato skins had normal weight gain showing that they are safe to eat. ARS scientists in Albany, California found that potato skins also contain significant amounts of the same polyphenols found in grapes, apples, cinnamon, and other foods with healthful properties. Polyphenols are useful in reducing the adverse metabolic effects of weight gain. Potato skins may be a safe and useful dietary ingredient to improve health in overweight individuals.
The lead scientist for this project is the U.S. Department of Agriculture (USDA) organizer for the American Chemical Society's Project SEED program. The Project SEED program provides summer research experience for disadvantaged high school students and includes a stipend from the American Chemical Society (ACS). This summer the program has about 45 students in the Northern California area. In this project, a postdoctoral scientist mentored a high school student through the ACS Project SEED program.
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