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ARS Home » Southeast Area » Raleigh, North Carolina » Food Science and Market Quality and Handling Research Unit » Research » Research Project #429741

Research Project: Improvement and Maintenance of Flavor, Shelf Life, Functional Characteristics, and Biochemical/Bioactive Components in Peanuts, Peanut Products and Related Commodities through Improved Handling, ...

Location: Food Science and Market Quality and Handling Research Unit

2018 Annual Report

Objective 1. Determine the relationship between maturity, moisture, handling, and processing interactions with the fatty acid contents of peanuts that will potentially affect nutritional composition, flavor, shelf-life and texture characteristics of whole peanuts. Objective 2. Enable improved peanut flavor, flavor consistency and nutritional composition through integration of novel peanut genetic/genomic resources. Sub-objective 2.A. Evaluate the flavor and quality characteristics of specific peanut varieties or breeding lines in cooperation with U.S. peanut breeders. Sub-objective 2.B. Evaluate the flavor and quality characteristics of accessions in the peanut germplasm collection. Objective 3. Identify the bioactives and characterize their functional food attributes from raw/roasted peanuts and peanut skins.

The four market types, runners, virginias, spanish and valencias, will be examined for the development of high oleic to linoleic (O/L) after sorting lots at harvest into maturity classes to determine the relationship of O/L ratio to market type and maturity. Late generation peanut breeding lines and varietal checks included in the Uniform Peanut Performance Tests (UPPT) and from the USDA NPGS and grown out by the collaborators over three crop years will be examined for physical, chemical, and where possible sensory quality using constantly updated analytical equipment. Peanuts will be obtained from a commercial shelling operation for Identification and quantification, where possible, of the secondary metabolites.

Progress Report
With a value of over one billion dollars at the farm level, the peanut crop ranks as number twelve among U.S. food crops. In addition, the peanut industry is composed of producers, shellers, and manufacturers. The Market Quality and Handling Unit is focused on addressing critical problems facing these stakeholders. Problem areas include flavor, nutrition, processing, and value-added traits that are critical to delivering optimized peanut products. Maturity Determination. Samples of all four market type cultivars were supplied by various cooperators in the U.S. Analysis of bulk and single seed fatty acid content was completed and the data was statistically analyzed. The manuscript discussing the characteristics of seed maturity, moisture and oil content in relationship to market type is currently being composed. The amount of information has proven to be too large for a conventional peer reviewed journal article and is being drafted as a monograph. Uniform Peanut Performance Tests (UPPT). Samples of peanut varieties and breeding lines currently in development were provided by U.S. peanut breeders participating in the Uniform Peanut Performance Tests (UPPT) for the crop year 2017. Samples were analyzed for total fat, moisture content, fatty acid profiles, sugars profiles, tocopherols, and sensory characteristics by the descriptive panel. The data was compiled and reported to the cooperators and to the program website at National Peanut Research Laboratory. Secondary Metabolite Profiles of Peanuts. Metabolites were analyzed from raw and roasted runner and virginia peanuts. The results were summarized statistically and reported at the 2018 annual meeting of the American Peanut Research and Education Society. One manuscript was published in a peer reviewed journal (Food Chemistry) and a second manuscript was submitted to the Journal of Food Science and is in revision. Use of Peanut Skins as a Functional Ingredient. Peanut skin extracts were spray dried to produce a free flowing, water soluble powder with measurable antioxidant activity. The powder was incorporated into two flavored mixes and used to coat peanuts. The chemical antioxidant activity of the flavor coated peanuts was measured and found to be two to three times higher than the uncoated peanuts and higher than fruits such as strawberries and blueberries which are known for their antioxidant contents. A consumer liking test was conducted and the flavor coated peanuts were compared to commercial products and found to be as acceptable as those products. A manuscript describing the antioxidant activity and the consumer acceptance of the products was submitted to a peer reviewed journal (Journal of Food Science). Health Effects of Peanut Skins Extract. Extracts of the phenolic compounds from peanut were found to reduce blood glucose levels, liver toxicity and improve the health of mice when incorporated into an atherogenic diet. A control of standard mouse diet and an atherogenic diet (high-cholesterol, high fat) without added peanut skin extract was fed to the control groups. A manuscript is being prepared for submission to a peer reviewed journal. Graduate Students: 4 graduate students in the Department of Food, Bioprocessing, and Nutrition Sciences at North Carolina. Outside Grant Funding: Awarded 2018-2019 6th Round ARS Innovation Award - Research Proposal, “Improvement and Maintenance of Flavor, Shelf Life, Functional Characteristics, and Biochemical/Bioactive Components in Peanuts and Peanut Products." Awarded 2018-2019 North Carolina Peanut Growers Association Funding - Research Proposal, The Impact of High-Oleic Peanut Diet on the Fatty Acid Profile, Nutrient Profile and Sensory Attributes of Shell Eggs and Meat Produced from Layer Hens and Broiler Chickens.” Awarded 2017-2018 4th Round ARS Innovation Award - Research Proposal, “Improvement and Maintenance of Flavor, Shelf Life, Functional Characteristics, and Biochemical/Bioactive Components in Peanuts and Peanut Products".

1. Waste peanut skins produce a functional food ingredient. Utilization of waste peanut skins from peanut blanching plants was made by extracting the skins with an aqueous solvent mixture and spray drying the extracts with maltodextrin to produce a free-flowing powder with reduced bitter flavor. ARS researchers at Raleigh, North Carolina, produced a powder that was incorporated into flavored coating mixes. The coating mixes were used to make flavor peanuts that had similar or higher antioxidant values than fruits such as strawberries and blueberries due to the phenolic compounds present in the new functional ingredient. A practical application of waste peanut skins was developed and found acceptable by peanut consumers that will add value to this material. The study was published in a peer reviewed journal.

2. A new cashew product was evaluated for the nutritional composition. Nut skins are known for their high phenolic content which has chemical antioxidant activity. A process which removes the caustic oil from cashew skins was developed by a cooperator in India which allows for skin on cashews to be produced human consumption. ARS researchers at Raleigh, North Carolina, evaluated the nutritional composition of the skin on cashews and compared them to raw and dry roasted cashews. The new product was found to have similar nutrient levels and to be higher in antioxidant activity to the other types of cashews. This work was used prepare point of sale information for consumers and to promote the new cashew product. This product was awarded a new product award at a trade show for natural products.

3. Peanut nutrition and flavor is affected by roasting conditions. This work was used prepare point of sale information for consumers and to promote the new cashew product. This product was awarded a new product award at a trade show for natural products. The changes in peanut nutritional composition and flavor with roasting parameters in a simulated industrial setting were determined. ARS researchers at Raleigh, North Carolina, used a pilot scale roaster that simulated an industrial belt-type roaster to determine how changes in time, temperature and air flow affect the quality of roasted peanuts. Optimal conditions were determined for jumbo runner type peanuts.

4. Chemical composition of entries in the 2017 Uniform Peanut Performance Tests. Peanut cultivars from the 2017 Uniform Peanut Performance Tests were evaluated for chemical and sensory characteristics. Samples from five USA peanut breeders were submitted to ARS researchers at Raleigh, North Carolina, after processing at Dawson, Georgia, location. The breeders are cooperators from Universities, private corporations and other ARS units. Samples were analyzed for moisture, total lipid, fatty acid profiles, sugars, and tocopherols using established methods. The flavor characteristics of the samples after dry roasting were evaluated by the descriptive sensory panel maintained by the unit. The results were reported on the website of program so that the information can be used by the cooperators and others in the peanut industry for the suitability of new cultivars for growing areas and food processing.

5. Profiles of secondary metabolites in raw and roasted peanuts. A non-targeted metabolomics study was used by ARS researchers Raleigh, North Carolina, to evaluate raw and roasted peanuts of the runner and virginia market types. Pathways analysis was performed to determine the source of the compounds identified from the composition of the starting materials. Various statistical models were used to evaluate the data. Using the information, targeted analyses were performed to determine the actual content of certain metabolites. From this study, valuable information was obtained about the composition of peanuts and compounds that serve as precursors to roasted peanut flavor and nutrients. This study will be important to peanut breeders needing to identify genetic markers for certain traits and components to increase the sustainability and value of the USA peanut crop.

6. The flavor and nutritional composition of peanuts is dependent on the maturity of the peanut kernel and can vary with market type. The peanut is an indeterminate flowering plant. As such, peanut pods on the plant are not all at the same level of maturity at harvest. The degree of maturity affects the peanut composition in that lipid levels, fatty acid profiles, protein and carbohydrate levels all change as the peanut matures. These factors impact the flavor and texture of roasted peanuts. ARS researchers in Raleigh, North Carolina, evaluated the composition of peanuts from each of the four market types, runner, virginia, spanish and valencia, and determined the impact that maturity has one each. This information will provide growers with parameters to follow to insure optimum quality. Processor will be able to use the information to select growing areas and market types to suit their end use.

7. The incorporation of high oleic peanuts into poultry feed improves the nutritional levels of eggs. Egg producers have information on using high oleic peanuts in their hen feeding regimens to increase yellow color in eggs yolks and increase oleic acid levels in the eggs as well. Eggs produced by layer hens fed a diet containing high-oleic peanuts had significantly greater intense yellow color, Beta-carotene (Vitamin A precursor) and total oleic fatty acid content in comparison to eggs produced by hens fed a conventional diet. ARS researchers at Raleigh, North Carolina, used high-oleic peanuts in study of poultry feed to enrich the nutritional content of eggs from layer hens. Improved vitamin levels and fatty acid profiles resulted. The study was funded by an ARS Innovation Award.

8. The extracts from waste peanut skins improved the health of mice. Adult male mice were assigned to one of three treatments: standard mouse chow diet, atherogenic (high-cholesterol, high fat) diet, or atherogenic diet with added peanut skin extracts. The extracts were prepared from waste peanut skins using aqueous food grade solvents and spray dried to produce a free-flowing powder. ARS researchers at Raleigh, North Carolina, evaluated the blood and body weights of the mice over the course of 16 weeks. Mice fed the diet containing the peanut skin extract were found to have reduced blood glucose levels, reduced liver toxicity, and improved overall health when compared to mice fed the atherogenic diet alone. This animal model demonstrated that peanut skin extracts as a food ingredient have the potential for positive impact on human health.

Review Publications
Klevorn, C.M., Dean, L.L. 2017. A metabolomics-based approach identifies changes in the small molecular weight compound composition of the peanut as a result of dry-roasting. Food Chemistry. 240:1193-1200.
Griffin, L.E., Dean, L.L. 2017. Nutrient composition of raw, dry-roasted, and skin-on cashews. Journal of Food Research. 6(6):13-28.
Toomer, O.T., Pereira, M., Do, A., Williams, K. 2017. Gender and dose dependent ovalbumin induced hypersensitivity responses in murine model of food allergy. Journal of Food, Nutrition and Population Health. 1:1-6.
Hao, Z., Malyala, D., Dean, L.L., Ducoste, J. 2017. Attenuated total reflectance fourier transform infrared spectroscopy for determination of long chain free fatty acid concentration in oily wastewater using the double wavenumber extrapolation technique. Talanta. 165:526-532. https://doi:10.1016/j.talanta.2017.01.006.
Shi, X., Dean, L.L., Sandeep, K.P., Davis, J.P., Sanders, T.H. 2017. The effects of different dry roast parameters on peanut quality using an industrial, belt-type roaster simulator. Food Chemistry. 240:974-979. https://doi:10.1111/jfpe.12498.