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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

2019 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 issues of flavor, nutrition, processing, and value-added products that are critical to delivering optimized peanut products across all peanut industry segments. Maturity Determination. Samples of the four peanut market type cultivars (runner, virginia, spanish, valencia) were supplied by various cooperators in the USA. Analysis of bulk and single seed fatty acids, moisture and total oil contents was performed and the data was statistically analyzed. Several peer reviewed manuscripts were published with one currently in review at the journal. The study described the relationship of peanut seed maturity, moisture and oil content in relationship to market types was described. A larger monograph of all the information is being drafted. Uniform Peanut Performance Tests (UPPT). Samples of peanut varieties and breeding line currently in development were provided by participating USA peanut breeders in the Uniform Peanut Performance Tests (UPPT) for the crop year 2018. Samples were analyzed for total fat, total protein, moisture content, fatty acid and sugar profiles, tocopherol content and sensory characteristics after roasting by a trained descriptive sensory panel. Creation of the data set is still in progress as the samples were received later than normal this year. The data will be compiled and reported to the cooperators and to the program website at the USDA, ARS National Peanut Research Laboratory. Oil Development in Peanuts as Affected by Growing Location. Peanut varieties with varying oil composition were grown at several locations in the USA. Evaluation of the total oil and the fatty acid profiles was performed. Results were reported to the cooperator for publication in a peer reviewed manuscript. This is a multiyear ongoing project to evaluate the suitability of peanut cultivars to growing regions in cooperation with the USDA ARS Wheat, Peanut, and Other Field Crops Unit in Stillwater, OK. Secondary Metabolite Profiles of Peanuts. A series of targeted and non-targeted analyses of the metabolites present in raw and roasted runner and virginia type peanuts was performed. The results were statistically analyzed and published in two peer reviewed journal articles. An additional study concentrating on the volatile compounds that have roasted peanut flavor impact is being completed. Progress was reported at the 2018 annual meeting of the American Peanut Research and Educational society and a manuscript for peer review is being prepared. Use of Peanut Skins as a Natural Antioxidant. Extracts of peanut skins were prepared and encapsulated with maltodextrin to create a food additive. The antioxidant properties were evaluated by a series of additions to commercial peanut butter. The samples were stored under accelerated conditions for a shelf life study over six months. The samples were evaluated for flavor by a descriptive sensory panel using the standard peanut lexicon. Chemical analysis of oxidation products was performed. The data is currently being evaluated. Use of Peanut Skins as a Functional Food Ingredient and Its Effects on Human Glycemic Response. Previous research from the Market Quality and Handling Research Unit has produced a functional food ingredient from peanut skins, a food processing waster material. This ingredient has shown antioxidant activity in chemical assays and anti-inflammatory effects in cell culture. Sensory analysis with consumers has proven that the material is acceptable as a food ingredient with minimal negative flavor impacts. Use of the ingredient as part of a flavored coating for roasted peanuts had a moderating influence on the glycemic response of young, healthy adults who consumed the products. This study was published in a peer reviewed publication (PLOS ONE). Peanut Composition of Commercial Cultivars. A study of peanut composition of selected current cultivars is being initiated in cooperation with the Department of Food Science at the University of Georgia. Seeds of the selected cultivars have been obtained and planted at the USDA, ARS National Peanut Laboratory in Dawson, Georgia. After harvesting and curing, analyses will be performed. Provided technical supervision to 3-Graduate Students in the Department of Food, Bioprocessing, and Nutrition Sciences at North Carolina State University. Additional funding was awarded to an ARS researcher: 2019-2020, “Flavor, texture and protein characterization of commercially available peanut varieties in in Southeast U.S. by sensory evaluation and instrumental techniques”, in cooperation with the University of Georgia. Phenolic compound extracts from peanut skins were incorporated in an atherogenic (high in saturated fatty acids and cholesterol) murine diet to determine anti-inflammatory and biological effects of peanut skin phenolic extracts in vivo. Mice were fed either a control diet, diet high in saturated fatty acids and cholesterol alone or a diet high in saturated fatty acids enriched with phenolic extracts from peanut skins to adult mice for 16 weeks. Tissues were collected for analysis and study results are published. Broiler meat-type chickens were fed a diet of 1. Non-roasted whole unblanched high-oleic peanuts and corn, or 2. A control diet, or 3. A control diet supplemented with 6% oleic fatty acid oil to determine the effects on the nutritional profile, sensory attributes, and quality of the meat produced and broiler performance. From this study, two manuscripts have been prepared. The results of the meat quality, sensory attributes and broiler performance data has been published. The nutritional content data analyzed from chicken breast samples is currently being analyzed, summarized and prepared for publication. Layer hens were fed a diet of 1. Non-roasted whole unblanched high-oleic peanuts and corn, or 2. Conventional layer hen diet (soybean meal and corn), or 3. A control diet supplemented with 6% oleic fatty acid oil to determine the effects on the fatty acid profile and sensory attributes of table eggs produced and hen performance. This study was conducted to help determine the usefulness of high-oleic peanuts within the poultry feed industry. All data has been collected, analyzed, summarized and prepared for publication. Layer hens were fed a diet of 1. Non-roasted whole unblanched high-oleic peanuts and corn, or 2. Conventional control layer hen diet, or 3. A control diet supplemented with 3% peanuts skins, or 4. A control diet supplemented with 6% oleic fatty acid oil to determine the effects on the fatty acid profile of table eggs produced and hen performance. This study was conducted to help determine the usefulness of peanut skins and/or whole unblanched high-oleic peanuts within the animal feed industries. Data is being collected currently and will be analyzed, summarized and prepared for publication. An agreement is currently being established to determine the comparative antimicrobial and bioactive components of essential oils and extracts from U.S. and Malaysian peanut cultivars with varying seed coats using in vitro and/or in vivo methodologies. This project is targeted to begin August 2019.

1. Profiles of secondary metabolites in raw and roasted peanuts. A non-targeted metabolomics study was used by ARS scientists in 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.

2. 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 scientists 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. Processors will be able to use the information to select growing areas and market types to suit their end use.

3. 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 in 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. The antioxidant and consumer perception studies were published in a peer reviewed journal. USA Producers of peanut products such as roasted peanut and peanut butter produce hundreds of thousands of pounds of this material annually that currently disposed of as waste material or low-grade animal feed. This research shows practical application of food processing waste material to produce a value-added food ingredient which can provide human health benefits.

4. Chemical composition of entries in the 2018 Uniform Peanut Performance Tests. Peanut cultivars from the 2018 Uniform Peanut Performance Tests were evaluated for chemical and sensory characteristics. Samples from five USA peanut breeders were submitted to ARS scientists in Raleigh, North Carolina, after processing by ARS scientists in Dawson, Georgia. 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 to participants in the program and are available to other interested parties on demand 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.

Review Publications
Klevorn, C.M., Dean, L.L., Johanningsmeier, S.D. 2019. Metabolite profiles of raw peanut seeds reveal differences between market-types. Journal of Food Science. 84(3):397-405.
Toomer, O.T., Hulse-Kemp, A.M., Dean, L.L., Boykin, D.L., Ramon, M., Anderson, K.E. 2019. Feeding high-oleic peanuts to layer hens enhances egg yolk color and oleic fatty acid content in shell eggs. Poultry Science. 98:1732-1748.
Toomer, O.T., Vu, T.C., Pereira, M., Williams, K. 2019. Dietary supplementation with peanut skin polyphenolic extracts (PSPE) reduces hepatic lipid and glycogen stores in mice fed an atherogenic diet. Journal of Functional Foods. 55:362–370.
Toomer, O.T. 2018. A comprehensive review of the value-added uses of peanut(Arachis hypogaea) skins and by-products. Critical Reviews in Food Science and Nutrition. 30:1-10.
Christman, L.M., Dean, L.L., Bueno-Almeida, C., Weissburg, J.R. 2018. Acceptability of peanut skins as a natural antioxidant in flavor coated peanuts. Journal of Food Science. 83(10):2571-2577.
Christman, L.M., Dean, L.L., Allen, J.C., Feng Godinez, S., Toomer, O.T. 2019. Peanut skin phenolic extract attenuates hyperglycemic responses in vivo and in vitro. PLoS One. 14(3):e0211459.
Lima, H.K., Vogel, K., Wagner-Gillespie, M., Hubble, C., Dean, L.L., Fogelman, A.D. 2018. Nutritional comparison of raw, holder pasteurized and shelf-stable human milk products. Journal of Pediatric Gastroenterology and Nutrition. 66(5):649-653.
Perrin, M.P., Pawlak, R., Dean, L.L., Christis, A., Friend, L. 2018. A cross-sectional study of fatty acids and brain derived neurotrophic factor (BDNF) in human milk from lactating women following vegan, vegetarian, and omnivore diets. American Journal of Clinical Nutrition. pp. 1-10.
Toomer, O.T., Livingston, M.L., Wall, B., Sanders, E., Vu, T.C., Malheiros, R., Livingston, K.A., Carvalho, L.M., Ferket, P.R. 2019. Meat quality and sensory attributes of meat produced from broiler chickens fed a high oleic peanut diet. Poultry Science. 98(10):5188-5197.