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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

2020 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
This is the final report for this project, which terminated in July 2020. All planned experiments were completed prior to this report. There were several tangible results realized over the 5 years of the project. ARS researchers at Raleigh, North Carolina, determined that the growth and development of peanuts takes place entirely underground. Since peanut plants are indeterminate flowering, new kernels are constantly being set throughout the lifetime of the plant up to the time of harvest. At harvest, there are no visible indicators as to the maturity of the peanut kernels produced. ARS researchers at Raleigh, North Carolina, determined the actual maturity of the kernels was found to have substantial effects on the quality of the peanut produced, most importantly in high oleic varieties whose longer shelf life is a result of high levels of monounsaturated fatty acids than the conventional normal oleic varieties. The development of fatty acids at maturity was proven in all four of the peanut market types. ARS researchers at Raleigh, North Carolina, believe sorting by size will not necessarily reduce the content of immature peanuts in a lot, but has proven to be the most effective means to ensure the quality of the lot by reducing the number of normal oleic peanuts in high oleic lots. The US peanut germplasm collection contains 7,000 accessions which can be used for conventional breeding of new cultivars with improved drought, disease and insect damage resistance and produce higher yield and peanut grade. Chemical composition and peanut flavor are of importance to peanut consumers. Determination of these characteristics was done by ARS researchers at Raleigh, North Carolina, to provide information as to how accessions from the collection will affect them when used as breeding material. This is a valuable resource provided to conventional breeders and those searching for genetic markers of these traits. Using a metabolomics approach, ARS researchers at Raleigh, North Carolina, determined it was possible to identify 365 compounds in runner and virginia peanuts that characterize their composition and indicated how the market types differ. This information was provided by ARS researchers at Raleigh, North Carolina, in the first report of peanut composition using this non targeted approach. Using this methodology, ARS researchers at Raleigh, North Carolina, compared roasted peanuts to raw peanuts to define how roasted peanut flavor develops. This information will lead to more genetic markers identified for USA peanut flavor, which has proven to be the most highly marketable characteristic for global peanut sales. The usefulness of feeding unblanched (skin on) high oleic peanuts to layer hens was proven by the production of eggs with different fatty acid profiles and more highly colored yolks. ARS researchers at Raleigh, North Carolina, determined that broiler chickens fed unblanched high oleic peanuts were found to be equivalent to those fed conventional soybean/corn diets in tests of the sensory characteristics of the breast meat with consumers. Financial support for this work was provided by the 4th, 6th and 10th rounds of the ARS Innovation Funds and by grants from the North Carolina Peanut Growers Association in 2018, 2019 and 2020. Peanut skins are a substantial waste problem for the peanut blanching industry. Products such as peanut butter and candy use blanched peanuts. The skins have proven to be a source of small phenolic compounds with noted bioactivity. In addition to chemical antioxidant properties, they have been shown have anti-inflammatory effects in cell culture. In mouse models, peanut skins significantly mitigated the effects on the livers, spleens and blood chemistry of feeding an atherogenic diet. Production of a free-flowing powder from ethanolic extracts was done by ARS researchers at Raleigh, North Carolina, using maltodextrin encapsulation. Use of this powder as a food ingredient increased the chemical antioxidant value of flavor coated peanuts and milk chocolate. Consumers were unable to detect the presence of the ingredient in the products as the encapsulation mitigated the bitter flavor. This provides a use for the waste material as well as providing preservative and human health benefits to the products incorporating the ingredient.

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 scientists at Raleigh, North Carolina, produced a powder that was incorporated in commercially prepared peanut butter. The chemical antioxidant value as measured by a spectrophotometric assay was increased. The shelf life as determined by descriptive sensory analysis and the presence of fatty acid oxidation products as measured by gas chromatography coupled with mass spectrophotometry was not found to be increased by the presence of the material at levels up to 2% by weight.

2. Chemical composition of entries in the 2018 Uniform Peanut Performance Tests. Peanut cultivars from the 2018 Uniform Peanut Performance Tests were evaluated by ARS researchers at Raleigh, North Carolina, for chemical and sensory characteristics. Samples from five USA peanut breeders were submitted to ARS at Raleigh, North Carolina, after processing at the National Peanut Research Laboratory 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 ARS researchers at Raleigh, North Carolina. 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.

3. 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 at 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 on each. This information was published in a peer reviewed journal and will provide growers with parameters to follow to ensure optimum quality. Peanut Product Processors will be able to use the information to select growing areas and market types to suit their end use.

4. Innovation funds award. ARS researchers at Raleigh, North Carolina, were awarded the 4th, 6th and 10th Round ARS Innovation Funds for the value-added utilization of high-oleic peanuts and/or agricultural by-products such as peanut skins as a feed ingredient in animal production.

5. 2020 North Carolina Peanut Growers Grant to fund award. ARS researchers at Raleigh, North Carolina, were awarded a 2020 North Carolina Peanut Growers Grant to fund research to further validate the utilization of in shell-whole peanuts, or high-oleic peanuts and/or peanut skin waste as a feed ingredient in poultry and egg production. The data generated from these studies have either been published and/or currently in preparation for publication in peer-reviewed scientific journals.

Review Publications
Warren, M.F., Vu, T.C., Toomer, O.T., Fernandez, J.D., Livingston, K.A. 2020. Efficacy of 1-a-Hydroxycholecalciferol supplementation in young broiler feed suggests reducing calcium levels at grower phase. Frontiers in Veterinary Science. 7:245.
Toomer, O.T., Sanders, E., Vu, T.C., Livingston, M., Wall, B., Melheiros, R.D., Carvalho, L.V., Livingston, K.A., Ferket, P.R., Anderson, K.E. 2020. Potential transfer of peanut and/or soy proteins from poultry feed to the meat and/or eggs produced. ACS Omega. 5(2):1080-1085.
Dean, L.L., Eickholt, C.M., Lafountain, L.J., Hendrix, K. 2020. Effects of maturity on the development of oleic acid and linoleic acid in the four peanut market types. Journal of Food Research. 9(4):1-9.
Toomer, O.T., Livingston, M., Wall, B., Sanders, E., Vu, T.C., Malheiros, R., Livingston, K., Carvalho, L., Ferket, P.R., Dean, L.L. 2020. Feeding high-oleic peanuts to meat-type broiler chickens enhances the fatty acid profile of the meat produced. Poultry Science. 99:2236-2245.