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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

2017 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
Objective 1. Samples of spanish and valencia cultivars were received from Oklahoma and New Mexico cooperators. Fatty acid analysis of bulk and single seed fatty acid content was determined and statistically analyzed. The manuscript discussing the characteristics of maturity, moisture and oil content in comparison with runner and virginia peanuts is in preparation. Objective 2. Sub-objective 2A. Samples of peanut varieties and breeding lines currently in development were received from U.S. peanut breeders participating in the Uniform Peanut Performance Tests (UPPT) for the crop year 2016. Samples were analyzed for total fat, moisture content, fatty acid profiles, sugar profiles, tocopherols and sensory characteristics by the descriptive panel. The data was compiled and reported to the cooperators and to the program website. Objective 2. Sub-objective 2B. No samples of accessions from the U.S. peanut germplasm collection for the third year of the project were received from the cooperator at Auburn University, as the funding was not available. The results from previous years were reported to the cooperator and contributions were made to a manuscript in preparation by the cooperator. This portion of the project is considered to be terminated. Objective 3. Non targeted and targeted analysis of the metabolites present in raw and roasted runner and virginia peanuts was performed. The results were statistically analyzed and reported at a national meeting. Two manuscripts have been prepared and submitted to peer reviewed journals. Objective 3. Jumbo runner peanuts were roasted using three different roasting techniques to three different roast color levels. The results were statistically evaluated and the effects on shelf life and roast peanut flavor were evaluated. Two manuscripts were published in peer-reviewed journals. Objective 3. Peanut skin extracts were spray dried to produce a free flowing, water-soluble powder with measurable antioxidant activity. The powder was incorporated into milk chocolate to produce a final product with equal or higher bioactivity than commercial dark chocolate. A manuscript describing the consumer acceptance of the product was published in a peer-reviewed journal. Objective 3. Peanut proteins from raw and dry roasted peanut flours were extracted for comparative analysis between cultivars and conventional and high-oleic breeding lines of peanuts. The data collection and analysis is ongoing and lab results will be completed and published in a peer-reviewed scientific journal by December 2018. Objective 3. 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 20 weeks. Tissues were collected for analysis and study results will be completed and published in a peer-reviewed scientific journal by December 2018. Objective 3. Layer hens were fed a diet of non-roasted whole high-oleic peanuts and corn or a conventional layer hen diet (soybean meal and corn) to determine the effect of high-oleic peanuts on the fatty acid profile of table eggs and hen performance. This study was conducted to help determine the usefulness of peanuts within the food and feed industries. All egg samples have been collected and are currently being analyzed. Study results will be completed and published in a peer-reviewed scientific journal by December 2018.

1. Usefulness of peanuts and peanut-by-products as a new food ingredient. ARS scientists in Raleigh, North Carolina, received an ARS Innovation Fund award for the utilization of peanut skin waste as a new dietary food ingredient. The phenolic compounds from peanut skins were extracted with an aqueous solvent and spray dried with maltodextrin to produce a free flowing powder to enhance peanut skin sensory attributes. This free flowing phenolic compound extract was incorporated into milk chocolate to enhance the nutritional value without adversely affecting flavor according to consumer sensory perceptions. The resulting chocolate product had a similar or higher antioxidant activity than dark chocolate due to the phenolic compounds present in the new functional ingredient. The consumer perception study was published in a peer-reviewed journal.

2. Development and publication of cashew flavor lexicon. A lexicon for the evaluation of cashew flavor and texture was created by ARS Scientists in Raleigh, North Carolina. Prior to this, no lexicon for cashews was available in the scientific literature. The sensory parameters were created and formalized by a descriptive panel. The lexicon was produced using commercial and experimental cashew products. The new lexicon was published in a peer reviewed journal.

3. Effects of roasting on peanut flavor attributes. ARS scientists at Raleigh, North Carolina, completed a multiyear comparative study of the effects of peanut variety, size, moisture content, oil content, geographical growing location, and roast time on peanut flavor and color attributes. The outcome will be of interest to commercial peanut roasters for the optimization of roasted peanut flavor when producing products from a range of starting materials. Information uncovered in the study concerning the timing of flavor development will aid sensory chemists with the identification of both positive and negative flavor components.

4. Comparative peanut roasting (dry, oil, blister frying) analysis on peanut flavor, color and shelf life. ARS scientists at Raleigh, North Carolina, used Jumbo runner peanuts and three types of commercial peanut roasting methods (conventional oil roasting, blister frying and dry roasting) to evaluate comparatively for optimum flavor and extended shelf life. The resulting colors were designated as light, medium and dark. Chemical and descriptive sensory evaluations were performed before and after storage under accelerated conditions. These results demonstrate that differing peanut flavor profiles, textures and shelf life are dependent upon each roasting method.

5. Chemical and sensory evaluation of peanut breeding lines. Peanut cultivars from the 2016 Uniform Peanut Performance Trials were evaluated for chemical and sensory characteristics. Samples were analyzed from five USA peanut breeders submitted to the ARS scientists in Raleigh, North Carolina, after processing at the National Peanut Laboratory in Dawson, Georgia. The breeders are cooperators from Universities and other ARS units. Samples were analyzed for moisture, total lipid, fatty acid profiles, sugars and tocopherols using established methods. The descriptive sensory panel evaluated the flavor characteristics of the samples after dry roasting. This information will be impactful to the peanut industry for the suitability of new cultivars for geographical growing regions and food processing.

6. Use of metabolic markers as a tool to improve peanut flavor. 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 the precursors to compounds responsible for flavors 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. This is the first reported study of the use of this approach to peanut science.

7. Handling and processing methods to enhance peanut flavor and shelf life of oil roasted peanuts. Oil roasting of peanuts produces unique and highly desirable peanut flavored products. Current commercial processing of oil-roasted peanuts has resulted in occurrences of defects in finished products that consumers have found to be undesirable. These included pooling of oil in containers or the opposite effect of dull peanut appearance with loss of adherence of added salt and other flavor enhancers. A study was conducted by ARS scientists in Raleigh, North Carolina, to evaluate the effects of moisture in raw peanuts before roasting and the process of cooling rate on oil-roasted peanuts. While initial moisture content had a major effect on final roasted peanut color, it was not found to be influential on causing defects in the final product. The rate of cooling after roasting was found to have an effect on the peanut appearance after roasting. Increased rates of cooling resulted in reduced the prevalence of dull roasted peanut surfaces and/or loss of flavor enhancers.

8. Usefulness of peanuts and peanut-by-products as a new food ingredient. Utilization of peanut skin waste acquired during the peanut blanching process was utilized as a functional food ingredient. ARS scientists in Raleigh, North Carolina, extracted the phenolic compounds from peanut skins using food-grade aqueous solvents and spray dried with maltodextrin to produce a free flowing powder, with considerable antioxidant activity. This free flowing phenolic compound extract was incorporated into savory seasoning mixtures and coated onto roasted peanuts via a panning procedure. The resulting coated products were evaluated and rated positively by consumers. Production of a functional food ingredient from waste peanut skins is a viable use of agricultural waste material produced by peanut blanching facilities that produce tons of peanut skin waste annually in the U.S.

Review Publications
Dean, L.L., Klevorn, C.M., Hess, B.J. 2016. Minimizing the negative flavor attributes and evaluating consumer acceptance of chocolate fortified with peanut skin extracts. Journal of Food Science. 81(Nr. 11):S2824-S2830. doi: 10.1111/1750-3841.13533.
Griffin, L.E., Drake, M., Dean, L.L. 2017. Development of a lexicon for cashew nuts. Journal of Sensory Studies. 32:e12244.
Shi, X., Davis, J.P., Xia, Z., Sandeep, K.P., Sanders, T.H., Dean, L.L. 2016. Characterization of peanuts after dry roasting, oil roasting, and blister frying. LWT - Food Science and Technology. 75:520-528.
Toomer, O.T. 2016. Nutrition education and promotion in the U.S. Journal of Food, Nutrition and Population Health. 1:1.
Toomer, O.T. 2017. Nutritional chemistry of the peanut (Arachis hypogaea). Critical Reviews in Food Science and Nutrition. 58(17):3042-3053.
Shi, X., Sandeep, K.P., Davis, J.P., Sanders, T.H., Dean, L.L. 2016. Kinetics of color development of peanuts during dry roasting using a batch roaster. Journal of Food Process Engineering. 40(3):1-9.