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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT & MAINTENANCE OF FLAVOR & SHELF-LIFE IN PEANUTS THROUGH IMPROVED HANDLING, PROCESSING AND USE OF GENETIC RESOURCES

Location: Market Quality and Handling Research

2006 Annual Report


1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter?
Since peanut flavor is the basis for marketing of peanuts, the issue being addressed is optimization of the vertically integrated system from peanut production to manufactured products that have consistent high flavor quality and shelf-life. The system is integrated because each successive process affects all that follow; however, process control passes from producer to handler to sheller to manufacturer to marketer. This system requires the definition, identification, and contribution of constituents and processes in related but separate activities that individually affect flavor and shelf-life of peanuts and peanut products. These issues are studied through examination of factors such as variety, maturity, farmers stock (in-shell) curing, moisture, blanching, storage, roasting, and the interactions within and among these parameters. Flavor and other quality characteristics of varieties and breeding lines is very limited until varieties are released and concerns in the industry dictate a needed change to conduct earlier flavor/quality evaluations. Very limited information is available on the nature or quantity of biochemical or bioactive compounds that may serve as markers for specific flavor defects, flavor intensity, or nutritional quality in peanuts. A need exists for identification of marker compounds so that rapid, inexpensive methods may be developed and utilized to define and predict flavor and nutritional quality of peanuts. Very little is known about the comparative quality of U.S. and other exporting country peanuts and development of this information should constitute valuable marketing information. A major concern of the peanut industry is to improve efficiency and reduce costs of handling associated with movement of peanuts from harvest through curing, a critical area of concern, and into storage. Microwave technology has the potential to be developed into a continuous flow system, dramatically reducing the time required to dry farmers’ stock peanuts, improve handling efficiency, and reduce costs.


2.List by year the currently approved milestones (indicators of research progress)
Year 1 (FY 2005) 1. – Roast and sort normal and off-flavor lots, complete initial sensory and other analyses, begin storage study. (objective 1, sub-objective 1a)

2. – Conduct initial evaluation. (objective 1, sub-objective 1c)

3. – U.S. Consumer study completed. Data analysis completed. (objective 1, sub-objective 1d)

4. – Breeding line sensory evaluations. (objective 1, sub-objective 1e)

5. – Osteoblast model system development. Crude extracts obtained and tested for activity. (objective 2, sub-objective 2a)

6. – Crude extracts from various plant parts examined for antioxidant activity. (objective 2, sub-objective 2b)

7. – Obtain high moisture peanuts. Generate different moisture control lots. Microwave samples and store roasted peanuts. (objective 3, sub-objective 3a)

8. – Obtain peanuts, examine internal and external temperature in microwave processed lots. (objective 3, sub-objective 3b)

9. – Design changes and upgrade. (objective 3, sub-objective 3c)

10. – Create off-flavor samples. Initial sensory and sniffer port analysis. (objective 3, sub-objective 3d)

Year 2 (FY 2006)

1. – Complete storage study complete analyses, compile data, present data. (objective 1, sub-objective 1a)

2. – Obtain and maturity sort peanuts, cure. Shell and roast. Store. (objective 1, sub-objective 1b)

3. – Windrow tests for year 1 completed and data analyzed. Variations in windrow configuration considered. (objective 1, sub-objective 1c)

4. – Consumer studies in UK, Germany, The Netherlands. (objective 1, sub-objective 1d) 5. – Seed increase. Prepare samples for sensory panel evaluation. Sensory evaluations. (objective 1, sub-objective 1e)

6. – Active fractions further fractionated by HPLC and tested. (objective 2, sub-objective 2a)

7. – Purified fractions examined. Data analysis. Presentation and publication. (objective 2, sub-objective 2b)

8. – Initial examination of various flavor samples by GC and GCO. (objective 2, sub-objective 2c)

9. – Lab analysis continues. Vary time, power, and airflow and repeat tests. (objective 3, sub-objective 3a)

10. – Conduct studies with combination of power, time, and airflow. Analyze samples. Store FS peanuts. (objective 3, sub-objective 3b)

11. – Initial tests and equipment modification. (objective 3, sub-objective 3c)

12. – Microwave time and power studies to identify parameters. Sensory analysis. (objective 3, sub-objective 3d)

Year 3 (FY 2007)

1. – Publication completed. (objective 1, sub-objective 1a)

2. – Storage analysis complete. (objective 1, sub-objective 1b)

3. – Tests for year 2 completed and data analyzed. Presentation. (objective 1, sub-objective 1c)

4. – International studies complete and all data analyzed for publication. (objective 1, sub-objective 1d)

5. – Complete evaluations and prepare publications. (objective 1, sub-objective 1e)

6. – Active compound identification by HPLC/MS. Presentations and publications initiated. (objective 2, sub-objective 2a)

7. – As warranted, active compounds isolated and identified. (objective 2, sub-objective 2b)

8. – Specific flavor issues selected and isolation of compounds. (objective 2, sub-objective 2c)

9. – Publication and presentation preparation. Additional tests and analyses as indicated by previous work. (objective 3, sub-objective 3a)

10. – Storage study data analysis. (objective 3, sub-objective 3b)

11. -- FS and blanching tests. Sample storage and analysis. Presentation and publication. (objective 3, sub-objective 3c)

12. – Snifferport analysis followed by GC/MS of causative compounds. (objective 3, sub-objective 3d)

Year 4 (FY 2008)

1. – Lab analyses complete and analyzed. Presentation of data. (objective 1, sub-objective 1b)

2. – Additional tests as needed or application of test results in large commercial fields. Presentation and publication. (objective 1, sub-objective 1c)

3. – Publication. (objective 1, sub-objective 1d)

4. – Compound Quantization continues. Presentation and publications completed. (objective 2, sub-objective 2a)

5. – Continued isolation and identification. (objective 2, sub-objective 2b)

6. – Identification of compounds continues. Presentation and publication. (objective 2, sub-objective 2c)

7. – Publication and presentation. (objective 3, sub-objective 3a)

8. – Modified studies to optimize process. Presentations. (objective 3, sub-objective 3b)

9. – Completion of economic analysis on optimized procedures. (objective 3, sub-objective 3c)

10. –Final identification of compounds. Presentation and publication. (objective 3, sub-objective 3d)

Year 5 (FY 2009)

1. – Investigations on secondary activity compounds. (objective 2, sub-objective 2a)

2. – Presentation and publication. (objective 2, sub-objective 2b)

3. – Continue work as indicated by results. (objective 2, sub-objective 2c)

4. – Publication and presentation preparation. (objective 3, sub-objective 3b)

5. – Presentation and Publication. (objective 3, sub-objective 3c)

6. -- Presentation and Publication. (objective 3, sub-objective 3d)


4a.List the single most significant research accomplishment during FY 2006.
Fruity fermented off flavor is a significant economic problem when the intensity of the flavor in a lot is not correctly measured. Sensory evaluation of 20 lots of fruity fermented peanuts provided data for development of a sampling plan for fruity fermented peanuts.


4b.List other significant research accomplishment(s), if any.
Timing of field studies involving off flavor provided information instrumental in changes by producers toward use of sandwich diggers as standard practice.

Consumers can identify low levels of fruity fermented flavor in peanut butter.

European consumers recognize the same off flavors as U.S. consumers and there is a greater probability of consumer complaints with peanuts from China and Argentina than those from U.S. sources.

Studies in which almonds were pasteurized with different treatments indicated that quality was not diminished by the processes.

In cooperative work, a lexicon was developed for Edemame which is a potential niche market crop for North Carolina and other areas.

Several volatile compounds were identified as being related to the total off note intensity in high temperature microwave blanched peanuts.


5.Describe the major accomplishments to date and their predicted or actual impact.
Some discoveries over the life of this and the previous project were:.
1)moisture at roasting is important to shelf-life of roasted peanuts,.
2)quality of Virginia-type in-shell peanuts is highly correlated to maturity of peanuts at harvest,.
3)resveratrol is present in very low concentrations in edible peanuts,.
4)commercial peanut butter has nondetectable levels of trans fatty acids,.
5)various bioactive compounds are present in peanuts,6) internal and external pod temperature are highly correlated in microwave drying, and.
7)pod color is not a quality factor difference in comparison of inshell peanuts from different origins .

Blanching of peanuts is a time consuming process and has potential to impact peanut flavor if high temperatures are used. Studies were conducted in cooperation with NC State University in the laboratories of the Market Quality and Handling Research Unit to examine the relationship between internal seed temperature detected by fiber optic probes and external temperature detected by infrared thermometry. Samples from the studies were used to examine the quality aspects of microwave blanched peanuts.

The first use of BLUP analysis to predict flavor of peanut progeny based on roast peanut intensity of parental lines indicated a moderate success of the use of the analysis.

In-shell peanuts roasted to dark color are not as acceptable to consumers as are lighter roasted in-shell colors, and manufacturers are concerned about this marketing issue. Studies were conducted in the laboratories of the Market Quality and Handling Research Unit in the Department of Food Science, NC State University in cooperation with Northampton Peanut Company to evaluate quality differences of in-shell peanuts roasted to different degrees of roast. The study indicated that lighter roasted in-shell peanuts contained more residual water, and thus, had shorter shelf-life than darker roasted peanuts, and although the aesthetic appearance might be more acceptable to consumers, the flavor loss and off-flavor development would be more objectionable. These data support continuation of current roasting practices of in-shell peanuts in the U.S. and provide manufacturers with marketing information on in-shell peanut quality.

Markets for U.S. in-shell peanuts in Canada and the U.K. were thought to be negatively impacted by differences in pod color with Chinese produced peanuts. In cooperation with the Virginia-Carolina Peanut Association, manufacturers in Canada and the U.K., and the American Peanut Council, studies were conducted in the laboratories of the Market Quality and Handling Research Unit located in the Department of Food Science, NC State University to evaluate pod color, oil quality and sensory characteristics of in-shell peanuts produced in the U.S. and China. The data demonstrated that pod colors were actually similar from the two origins, but oil and sensory quality were superior in the U.S.-produced peanuts. These data will contribute to market development and provide information on which improvements in pod aesthetics can be accomplished.

Tomato spotted wilt virus (TSWV) is the most important disease of peanut in the southeastern U.S. and there are concerns that this disease has a negative impact on roasted peanut flavor quality. We conducted sensory analysis of three TSWV resistant genotypes and one susceptible genotype using three market grade sizes. The sensory panel was able to taste a difference between infected and non-infected roasted peanuts, but differences were not related to any specific flavor attribute such as sweet, bitter, or roasted peanut. These data suggest to peanut product manufacturers that subtle differences in TSWV-infected and non-infected peanut flavor may or may not be detectable by consumers.

Flavor of peanut breeding lines being developed for commercial release as new varieties is highly important to manufacturers of peanut products. A trained sensory panel evaluated the flavor of 13 peanut breeding lines from 9 locations in the Uniform Peanut Performance Tests (UPPT). The evaluations again indicated some differences in flavor among the lines but indicated that all lines were of acceptable flavor quality. These data indicate to breeders working with these lines that continuation of development is warranted, and indicate to peanut shellers and manufacturers that forthcoming lines will have acceptable flavor characteristics.

There is a lack of data to demonstrate the superior quality of U.S. peanuts which can be used in marketing strategies to increase export sales of U.S. peanuts. We examined peanuts that had been shipped to Europe from the U.S., China, and Argentina. Data on oil quality and both descriptive sensory and consumer analysis of flavor clearly demonstrated the superior quality of U.S. peanuts. The data have been presented in various international forums and used in development of marketing information for U.S. peanuts.

Determination of roasted peanut flavor intensity as an inherited trait is of major significance because the estimates of broad-sense heritability are sufficiently high enough to permit standard breeding techniques to be employed to improve roasted peanut flavor intensity. Broad-sense heritability estimates and genotype-by-environment interactions for roasted peanut, sweet, bitter and other sensory attributes in peanuts were determined. The genotype-by-environment findings have provided the information necessary to design the most efficient field experiments for the quality traits under investigation. Information from this project has been used in breeding line evaluations from the Florida and North Carolina programs and contributed to release of SunOleic95R, SunOleic97R, NC 12C, Gregory, Florida MDR98, Perry, C-99R, DP-1, Carver, Hull (HO), and Norden (HO).

Fruity fermented peanuts can be effectively removed by color sorting to remove darker colored (immature) peanuts.

Sandwich windrow construction (plants placed in windrows with one up and one down providing shade for the peanuts) was demonstrated as the most effective and cost efficient method to decrease intensity of fruity fermented off flavor.

European consumer response to peanuts of different origins provided data which demonstrated that Europeans consumers have the same concept of what constitutes acceptable/good flavor as do consumers in the U.S. A greater percentage of peanut lots from China and Argentina have off flavors than do peanuts from the U.S. Because European consumers recognize the same off flavors as U.S. consumers there is a greater probability of consumer complaints with peanuts from China and Argentina. These data constitute positive marketing data for U.S. peanuts.


6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
Quality comparisons of U.S., Argentine, and Chinese peanuts have been presented to domestic and export industries and data are available for development of marketing strategies.

Data on quality comparisons of U.S., Argentine, and Chinese peanuts have been incorporated into workshops on peanut sensory characteristics and have been presented at international meetings .

Technology towards development of a continuous flow microwave curing process has been provided to microwave equipment developers

Information on peanut quality and flavor has been presented in American Peanut Council/FAS sponsored workshops and seminars in Mexico as part of promotion of export of U.S. peanuts into Mexico.


Review Publications
Boldor, D., Sanders, T.H., Swartzel, K.R., Simunovic, J. 2004. Thermal profiles and moisture loss during continuous microwave drying of peanuts. Peanut Science. 14:21-35.

Bolton, G.E., Sanders, T.H. 2002. Effect of high oleic acid peanut roasting oil on the stability of regular and partially defatted peanuts. Journal of the American Oil Chemists' Society. Vol. 79, pp 129-132.

Greene, J.L., Bratka, K.J., Drake, M.A., Sanders, T.H. 2005. Effectiveness of category and line scales to characterize consumer perception of fruity fermented flavor in peanuts. Journal of Sensory Studies. 21:146-154.

Isleib, T.G., Pattee, H.E., Sanders, T.H., Hendrix, K., Dean, L.L. 2006. Comparisons between normal-and high- oleic peanuts with respect to seed composition factors and sensory attributes. Journal of Agricultural and Food Chemistry. 54(9):1759-1763.

Schirack, A.V., Drake, M., Sanders, T.H., Sandeep, K.P. 2006. Impact of microwave blanching on the flavor of roasted peanuts. Journal of Sensory Studies. 21 (4) 428-440.

Last Modified: 9/10/2014
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