Research Food Technologist specializing in peanut science. Expertise in the chemical and nutritional composition of peanuts and related foods. USDA Research Professor of Food Science at North Carolina State University.
Abstract Peanuts are a globally important oilseed valued as a source of high-quality cooking oil.... more Abstract Peanuts are a globally important oilseed valued as a source of high-quality cooking oil. Peanuts are also appreciated worldwide as an affordable, flavorful, and nutritionally dense snack food, while also serving as a primary ingredient for peanut butter, confections, and nutritional bars, among other finished products. While amenable to a variety of processes, peanuts are commonly roasted and the unique, pleasant flavor of roasted peanuts is a primary driver in consumption. As a whole food and ingredient, peanuts are nutritionally dense, for example, providing the highest protein content of all commonly consumed snack nuts, serving as a rich source of heart-healthy, monounsaturated oil, and also providing a variety of healthy micronutrients and bioactive compounds that are becoming increasingly better understood with modern detection technologies and nutritional investigations. Research over the past century has provided a foundation for understanding the underlying chemical composition of peanut, and advances over recent years with modern instrumentation continue to improve insights into this chemistry and the various chemical and physical reactions and mechanisms responsible for peanut quality. Accordingly, this chapter focuses on advances in collecting chemical/physical data on peanuts and analyzing this information in the context of peanut quality, with an emphasis on delivering optimal flavor and nutrition. Beyond proximates, peanuts are also a rich source of various micronutrients, both water soluble and oil soluble, and these will be reviewed.
Peanut butter is a desirable product made from roasted peanuts that is susceptible to lipid oxida... more Peanut butter is a desirable product made from roasted peanuts that is susceptible to lipid oxidation during its shelf life. The process of lipid oxidation produces rancid aromas and flavors in peanut butter that have previously been found to be undesirable to consumers. Peanut skins, the paper-like coatings that surround peanut kernels, are a waste product of peanut processing that have been shown to contain phenolic compounds that could act as antioxidants which are able to inhibit lipid oxidation. Addition of peanut skin extracts to fresh peanut paste was evaluated for their effectiveness to retard oxidation of the lipids present. Extraction of the phenolic compounds and encapsulation with maltodextrin produced a free-flowing powder that was blended into freshly ground peanuts. The paste was packed into glass jars and incubated at 30 C and 26 % relative humidity. Control samples of peanut paste without the addition of the peanut skins extract ingredient were prepared using both b...
A number of soybean varieties traditionally bred for resistance to various soybean arthropod pest... more A number of soybean varieties traditionally bred for resistance to various soybean arthropod pests have been identified as resistant to Megacopta cribraria (F.) (Hemiptera: Plataspidae). However, the mechanisms of host-plant resistance (HPR) in this system are not understood. The goal of this study was to identify the mechanisms of resistance by examining the role of plant volatile organic compounds (VOCs) and free amino acids (FAAs) among 16 soybean varieties. Choice and no-choice cage experiments identified several soybean varieties that demonstrated antixenosis as well as antibiosis. However, resistance varied over time in certain soybean varieties, such as N02-7002 and PI567352B. Mean nymph number from choice experiments had positive correlations with the FAAs asparagine, tryptophan, alanine, phenylanaline, and serine; negative correlation with leucine and threonine. Four plant volatiles, hexanal, 2-pentylfuran, beta-cyclocitral, and cis-9-hexadecenal, were positively correlated with subsequent nymph development, whereas n-hexadecenoic acid was negatively correlated with nymph number only, in adult choice cage experiments. This study contributes to understanding the mechanisms of HPR through associations with plant VOCs and FAAs in relation to M. cribraria development and provides useful knowledge for developing soybean varieties for M. cribraria management.
In recent years, there has been increased interest in antioxidant-rich products by consumers want... more In recent years, there has been increased interest in antioxidant-rich products by consumers wanting to enhance the health benefits of their diet. Chocolate has been identified as a natural source of antioxidant compounds, which resulted in the development of polyphenol-enriched chocolate products that are now available commercially. This study investigated the use of phenolic compounds extracted from peanut skins as a novel antioxidant source for the enrichment of milk chocolate. The extracts were encapsulated with maltodextrin to lessen their bitterness. Antioxidant potential of the encapsulated peanut skin extracts was evaluated by the 2,2-diphenyl-1-picrylhydrazl radical quenching assay. Encapsulated peanut skins were found to have a corrected Trolox equivalency of 31.1 μmol/g of chocolate up to 0.8% (w/w). To produce a product with an antioxidant content similar to that of dark chocolate yet which maintained the milder flavor of milk chocolate, the best estimate threshold of encapsulated peanut skin extract in chocolate was 0.9 % (w/w) based on the standard method (American Society of Testing Materials; ASTM E-679). Consumer liking of milk chocolate enhanced by adding subthreshold (0.8 % (w/w)) inclusion levels of encapsulated peanut skin extract was found to be at parity with milk chocolate as a control.
Oxidative stability is an important factor considered by those in the peanut manufacturing indust... more Oxidative stability is an important factor considered by those in the peanut manufacturing industry. Product stability has been shown to increase up to seven-fold when high-oleic peanuts are used. The percentage of US crop that is high-oleic continues to increase, but many producers are reluctant to grow high-oleic cultivars due to the uncertainty of the high-oleic effect on agronomic traits, such as seed germination, yield and grade. Experiments were designed and conducted to examine the effect of the high oleic trait on peanut seed germination in field plots and in the laboratory on a thermal gradient table. Genotypes used in these experiments included cultivars or breeding lines from each peanut market-type along with their near-isogenic, high oleic counterparts. Field emergence, or germination, was recorded in the field in 4 geographically different regions, as well as in the laboratory on a thermal gradient table. Thermal gradient table experimental results demonstrated a lag i...
Abstract Peanuts are a globally important oilseed valued as a source of high-quality cooking oil.... more Abstract Peanuts are a globally important oilseed valued as a source of high-quality cooking oil. Peanuts are also appreciated worldwide as an affordable, flavorful, and nutritionally dense snack food, while also serving as a primary ingredient for peanut butter, confections, and nutritional bars, among other finished products. While amenable to a variety of processes, peanuts are commonly roasted and the unique, pleasant flavor of roasted peanuts is a primary driver in consumption. As a whole food and ingredient, peanuts are nutritionally dense, for example, providing the highest protein content of all commonly consumed snack nuts, serving as a rich source of heart-healthy, monounsaturated oil, and also providing a variety of healthy micronutrients and bioactive compounds that are becoming increasingly better understood with modern detection technologies and nutritional investigations. Research over the past century has provided a foundation for understanding the underlying chemical composition of peanut, and advances over recent years with modern instrumentation continue to improve insights into this chemistry and the various chemical and physical reactions and mechanisms responsible for peanut quality. Accordingly, this chapter focuses on advances in collecting chemical/physical data on peanuts and analyzing this information in the context of peanut quality, with an emphasis on delivering optimal flavor and nutrition. Beyond proximates, peanuts are also a rich source of various micronutrients, both water soluble and oil soluble, and these will be reviewed.
Peanut butter is a desirable product made from roasted peanuts that is susceptible to lipid oxida... more Peanut butter is a desirable product made from roasted peanuts that is susceptible to lipid oxidation during its shelf life. The process of lipid oxidation produces rancid aromas and flavors in peanut butter that have previously been found to be undesirable to consumers. Peanut skins, the paper-like coatings that surround peanut kernels, are a waste product of peanut processing that have been shown to contain phenolic compounds that could act as antioxidants which are able to inhibit lipid oxidation. Addition of peanut skin extracts to fresh peanut paste was evaluated for their effectiveness to retard oxidation of the lipids present. Extraction of the phenolic compounds and encapsulation with maltodextrin produced a free-flowing powder that was blended into freshly ground peanuts. The paste was packed into glass jars and incubated at 30 C and 26 % relative humidity. Control samples of peanut paste without the addition of the peanut skins extract ingredient were prepared using both b...
A number of soybean varieties traditionally bred for resistance to various soybean arthropod pest... more A number of soybean varieties traditionally bred for resistance to various soybean arthropod pests have been identified as resistant to Megacopta cribraria (F.) (Hemiptera: Plataspidae). However, the mechanisms of host-plant resistance (HPR) in this system are not understood. The goal of this study was to identify the mechanisms of resistance by examining the role of plant volatile organic compounds (VOCs) and free amino acids (FAAs) among 16 soybean varieties. Choice and no-choice cage experiments identified several soybean varieties that demonstrated antixenosis as well as antibiosis. However, resistance varied over time in certain soybean varieties, such as N02-7002 and PI567352B. Mean nymph number from choice experiments had positive correlations with the FAAs asparagine, tryptophan, alanine, phenylanaline, and serine; negative correlation with leucine and threonine. Four plant volatiles, hexanal, 2-pentylfuran, beta-cyclocitral, and cis-9-hexadecenal, were positively correlated with subsequent nymph development, whereas n-hexadecenoic acid was negatively correlated with nymph number only, in adult choice cage experiments. This study contributes to understanding the mechanisms of HPR through associations with plant VOCs and FAAs in relation to M. cribraria development and provides useful knowledge for developing soybean varieties for M. cribraria management.
In recent years, there has been increased interest in antioxidant-rich products by consumers want... more In recent years, there has been increased interest in antioxidant-rich products by consumers wanting to enhance the health benefits of their diet. Chocolate has been identified as a natural source of antioxidant compounds, which resulted in the development of polyphenol-enriched chocolate products that are now available commercially. This study investigated the use of phenolic compounds extracted from peanut skins as a novel antioxidant source for the enrichment of milk chocolate. The extracts were encapsulated with maltodextrin to lessen their bitterness. Antioxidant potential of the encapsulated peanut skin extracts was evaluated by the 2,2-diphenyl-1-picrylhydrazl radical quenching assay. Encapsulated peanut skins were found to have a corrected Trolox equivalency of 31.1 μmol/g of chocolate up to 0.8% (w/w). To produce a product with an antioxidant content similar to that of dark chocolate yet which maintained the milder flavor of milk chocolate, the best estimate threshold of encapsulated peanut skin extract in chocolate was 0.9 % (w/w) based on the standard method (American Society of Testing Materials; ASTM E-679). Consumer liking of milk chocolate enhanced by adding subthreshold (0.8 % (w/w)) inclusion levels of encapsulated peanut skin extract was found to be at parity with milk chocolate as a control.
Oxidative stability is an important factor considered by those in the peanut manufacturing indust... more Oxidative stability is an important factor considered by those in the peanut manufacturing industry. Product stability has been shown to increase up to seven-fold when high-oleic peanuts are used. The percentage of US crop that is high-oleic continues to increase, but many producers are reluctant to grow high-oleic cultivars due to the uncertainty of the high-oleic effect on agronomic traits, such as seed germination, yield and grade. Experiments were designed and conducted to examine the effect of the high oleic trait on peanut seed germination in field plots and in the laboratory on a thermal gradient table. Genotypes used in these experiments included cultivars or breeding lines from each peanut market-type along with their near-isogenic, high oleic counterparts. Field emergence, or germination, was recorded in the field in 4 geographically different regions, as well as in the laboratory on a thermal gradient table. Thermal gradient table experimental results demonstrated a lag i...
Uploads
Papers by Lisa Dean