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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

2008 Annual Report


1a.Objectives (from AD-416)
Determine the effect of production location, maturity, curing, seed moisture, composition, processing and relevant interactions to improve flavor and flavor consistency in peanut varieties and breeding lines. Identify, isolate, and characterize biochemcial/bioactive components in peanuts that influence or indicate flavor, flavor potential, off-flavor, or nutritional quality. Evaluate microwave heating to cure and blanch peanuts.


1b.Approach (from AD-416)
Individual effects of maturity, composition, and moisture content of individual seed and how these factors interact during blanching and subseqent oil and dry roast processing will be examined in varieties and breeding lines of peanuts grown in the Uniform Peanut Performance Trials (UPPT) at several different locations. Peanut samples with high standard flavor profiles, unique flavor profiles, and peanuts subjected to various deviations in production, curing, and handling procedures will be evaluated for variations in components identifiable by GC, HPLC, and other chromatographic methods. Compunds associated with specific flavor characteristics unique in presence or magnitude will be isolated and identified by GC-MS or HPLC-MS. Newly developed microwave technology that provides uniform exposure to microwave energy will be utilized to study the effects of various time and power protocols on drying rate, flavor, and shelf-life of shelled and inshell peanuts.


3.Progress Report
Flavor is one of the leading quality concerns in peanuts. Breeders must incorporate flavor evaluation alongside the traditional concerns of yield and pest resistance in order to maintain quality dominance. A trained sensory panel evaluated thirteen soon-to-be-released lines as well as selected early breeding stock in the 2007 Uniform Peanut Performance Trials. The data was distributed to aid breeders with their selections as well as to study the complex interactions between flavor and environment that are observed in peanuts. Samples representing most of the “Core of the Core” of the peanut germplasm collection from two different crop years were analyzed for nutritional components. Fatty acids, amino acids, tocopherols and total folates were determined. Research is on going to develop inhouse methodology to determine individual folates, as this may prove important in how folate is metabolized. In earlier studies peanuts have been found to contain some folates that differ from leafy green vegetables which are considered to be the major folates in the human diet. A study aimed at evaluating the antioxidant properties of hydrolyzed peanut proteins has been initiated. Alcalase hydrolysis increased antioxidant capacity more than three times as compared to the unhydrolyzed control near neutral pH, whereas for acidic applications, pepsin increased antioxidant capacity more than twice. Surface activity of all hydrolyzed preps increased after hydrolysis. Peanuts, fat free peanut meal, and peanut oil were included in the diets of hamsters especially bred to quickly develop heart disease when consuming high fat, high cholesterol diets. All diets contained 0.5% cholesterol and compared to the control diet (no peanut components) all the peanut component diets resulted in reduced total and LDL cholesterol. Peanut flours are commercially available high-protein, low-fat functional food ingredients prepared from processed roasted peanut seed. Rheological properties of model systems prepared from a range of these flours were documented. Further investigations into the rheological properties of peanut flours treated with the food grade enzyme, transglutaminase, have also been documented. Work into the potential allergenic response of peanut flours after treatment with transglutaminase has been conducted. Three journal articles describe this work. The quality of oil roasted peanuts is sometimes compromised by the presences of surface blemishes and failure of the finished product to retain oil absorbed during roasting. The effect of the moisture content of raw peanuts on the quality of the oil roasted peanuts was examined. High moisture resulted in more surface blemishes and loss of shine to the finish product. Further studies are planned using a wider range of raw peanut moistures to verify the conclusions. Progress relates to National Program 306 Quality and Utilization of Agricultural Products, Component 1 Quality Characterization, Problem Area 1b Methods to Evaluate and Predict Quality and Component 2 New Processes, New Uses, and Value-Added Foods and Biobased Products, Problem Area 2a New Product Technology.


4.Accomplishments
1. Cardio health characteristics of peanuts. Literature on the healthy components in peanuts is available but studies to demonstrate the activity of these compounds is not available. As an initial study to examine specific cardio metabolic activity of peanuts, peanuts, fat free peanut flour, and peanut oil were all shown to maintain a low level of total cholesterol and LDL cholesterol when incorporated on an equal calorie basis into high fat, high cholesterol diets fed to hamsters. These results are important to peanut marketing and to further identification of specific compounds responsible for these heart disease risk factor reductions. This accomplishment relates to National Program 306 Quality and Utilization of Agricultural Products, Component 2 New Processes, New Uses, and Value-Added Foods and Biobased Products, Problem Area 2a. New Product Technology.

2. Off-flavor compounds. Flavor compounds corresponding to artificially-created fruity fermented off-flavor and naturally occurring off-flavor proved to be generally the same. Two compounds were identified that could reliably act as a marker for the off-flavor and suggest the potential for development of a GC analytical method. This accomplishment relates to National Program 306 Quality and Utilization of Agricultural Products, Component 2 New Processes, New Uses, and Value-Added Foods and Biobased Products, Problem Area 2a. New Product Technology.

3. Nutritional compounds in peanut germplasm. Nutritional component analysis of the “Core of the Core” of the peanut germplasm collection was completed. The results indicated differences across the lines and suggested that some could be used in a breeding program for some of the traits. Breeding studies based on this work have been initiated. This accomplishment relates to National Program 306 Quality and Utilization of Agricultural Products, Component 1 Quality Characterization, Presentation, and Enhancement, Problem Area 1b Methods to Evaluate and Predict Quality.

4. Antioxidant compounds in peanuts. Peanut skins and shells were found to contain specific polyphenolic compounds with known antioxidant activity. When added to peanut oil, extracts from peanut skins and shells extended the cooking life of the oil. The work could logically contribute to oil with increased shelf life. This accomplishment relates to National Program 306 Quality and Utilization of Agricultural Products, Component 2 New Processes, New Uses, and Value-Added Foods and Biobased Products, Problem Area 2a. New Product Technology.

5. Oil roasted peanut characteristics. The moisture of raw peanuts was found to have an effect on quality after oil roasting. Shelf life was found to be inversely correlated to moisture. Surface blemishes were found to increase with moisture content. This work will help to resolve a current problem in oil roast processing of peanuts and result in higher quality products. This accomplishment relates to National Program 306 Quality and Utilization of Agricultural Products, Component 1 Quality Characterization, Presentation, and Enhancement, Problem Area 1c Factors and Process that Affect Quality.

6. Breeding for good roast peanut flavor Analysis was performed on 235 samples for the Uniform Peanut Performance Trials (UPPT). Samples were analyzed in triplicate for moisture, fat, tocopherols, sugars, fatty acids profiles and for sensory characteristics. These data are critical in development of new peanut varieties and have been used in the development of several released lines. This accomplishment relates to National Program 306 Quality and Utilization of Agricultural Products, Component 1 Quality Characterization, Presentation, and Enhancement, Problem Area 1b Methods to Evaluate and Predict Quality.

7. Microwave pasteurization potentials. Studies indicated little if any quality deterioration in almonds after exposure to microwave generated Salmonella kill temperatures. The work suggests that microwave technology could be used as a novel method of pasteurizing almonds. This accomplishment relates to National Program 306 Quality and Utilization of Agricultural Products, Component 2 New Processes, New Uses, and Value-Added Foods and Biobased Products, Problem Area 2a. New Product Technology.

8. Almond shelf life. Evaluation of almonds pasteurized by various commercial methods were examined over time to determine the effect of pasteurization on shelf life characteristics. The data indicated that, in general, shelf life was not significantly negatively affected by pasteurization. These data have been used in a large industry study and provide information on the potentials of currently available almond pasteurization processes. This accomplishment relates to National Program 306 Quality and Utilization of Agricultural Products, Component 2 New Processes, New Uses, and Value-Added Foods and Biobased Products, Problem Area 2a. New Product Technology.

9. Peanut biodiesel. Viscosity, density and propensity to crystallize, all of which are physical properties important to fuel performance, were measured for biodiesels prepared from the unrefined oils of 8 different peanut cultivars. Increased concentrations of long chain, saturated fatty acids, namely C:24, were found to increase the propensity of the biodiesels to crystallize at low temperatures. These data are important to the development of peanut lines with less long chain fatty acids for biodiesel applications. This accomplishment relates to National Program 306 Quality and Utilization of Agricultural Products, Component 1 Quality Characterization, Presentation, and Enhancement, Problem Area 1c Factors and Process that Affect Quality.

10. Peanut flour functionality. Peanut flour is a relatively well used ingredient from roasted peanuts. “Model” peanut butters have been successfully formulated using peanut flours, peanut oil and other ingredients. These formulations are being used to investigate ingredient interactions and potential applications. The information can be used by manufacturers to increase use of peanuts and in the development of new products. This accomplishment relates to National Program 306 Quality and Utilization of Agricultural Products, Component 2 New Processes, New Uses, and Value-Added Foods and Biobased Products, Problem Area 2a. New Product Technology.


5.Significant Activities that Support Special Target Populations
None.


6.Technology Transfer

None

Review Publications
Isleib, T.G., Tillman, B.L., Pattee, H.E., Sanders, T.H., Hendrix, K., Dean, L.L. 2007. Genotype-by-Environment Interactions for Flavor Attributes of Breeding Lines in the Uniform Peanut Performance Test. Peanut Science. 152.1.118.33 (under downloads), (2008) 35:55-60.

Sabliov, C.M., Boldor, D., Coronel, P., Sanders, T.H. Continuous microwave procession of peanut beverages. Journal of Food Processing and Preservation Research vol. 32.

Krause, A., Miracle, R.E., Sanders, T.H., Dean, L.L., Drake, M.A. 2008. The effect of refrigerated and frozen storage on butter flavor and texture. Journal of Dairy Science 91:455-465.

Dean, L.L., Davis, J.P., Shofran, B.G., Sanders, T.H. 2008. Phenolic Profiles and Antioxidant Activity of Extracts from Peanut Plant Parts. Open Natural Product Journal. Vol. 1:1-6.

Greene, J.L., Sanders, T.H., Drake, M. 2008. Characterization of volatile compounds contributing to naturally occurring fruity fermented flavor in peanuts. Journal of Agricultural and Food Chemistry 56 (17)8096-8102.

Last Modified: 7/28/2014
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