Lisa L. Dean

Compositional and mechanical properties of peanuts roasted to equivalent colors using different time/temperature combinations.

Peanuts in North America and Europe are primarily consumed after dry roasting. Standard industry practice is to roast peanuts to a specific surface color (Hunter L-value) for a given application; however, equivalent surface colors can be attained using different roast temperature/time combinations, which could affect product quality. To investigate this potential, runner peanuts from a single lot were systematically roasted using 5 roast temperatures (147, 157, 167, 177, and 187 °C) and to Hunter L-values of 53 ± 1, 48.5 ± 1, and 43 ± 1, corresponding to light, medium, and dark roasts, respectively. Moisture contents (MC) ranged from 0.41% to 1.70% after roasting. At equivalent roast temperatures, MC decreased as peanuts became darker; however, for a given color, MC decreased with decreasing roast temperature due to longer roast times required for specified color formation. Initial total tocopherol contents of expressed oils ranged from 164 to 559 μg/g oil. Peanuts roasted at lower temperatures and darker colors had higher tocopherol contents. Glucose content was roast color and temperature dependent, while fructose was only temperature dependent. Soluble protein was lower at darker roast colors, and when averaged across temperatures, was highest when samples were roasted at 187 °C. Lysine content decreased with increasing roast color but was not dependent on temperature. MC strongly correlated with several components including tocopherols (R(2) = 0.67), soluble protein (R(2) = 0.80), and peak force upon compression (R(2) = 0.64). The variation in characteristics related to roast conditions is sufficient to suggest influences on final product shelf life and consumer acceptability.

Content of Some Nutrients in the Core of the Core of the Peanut Germplasm Collection

Abstract The usefulness of core collections of germplasm collections has been well established. The U.S. germplasm collection for peanuts was selectively reduced based on morphological characteristics to a mini core or “Core of the Core” collection composed of 112 of the 7432 accessions in the whole collection to make it more efficient for study. Of these samples, 108 were available from one location in the same year and were therefore exposed to one set of environmental conditions wherein genetic variability could also be examined. These samples were analyzed for total and individual amino acid content, fatty acid content, tocopherols, and folic acid content. These data provide a starting point for establishing nutrient composition within these accessions and provide an early indication of currently important characteristics in these lines which might be suited for use in random breeding initiatives.

Peanuts, peanut oil, and fat free peanut flour reduced cardiovascular disease risk factors and the development of atherosclerosis in Syrian golden hamsters.

Human clinical trials have demonstrated the cardiovascular protective properties of peanuts and peanut oil in decreasing total and low density lipoprotein cholesterol (LDL-C) without reducing high density lipoprotein cholesterol (HDL-C). The cardiovascular effects of the nonlipid portion of peanuts has not been evaluated even though that fraction contains arginine, flavonoids, folates, and other compounds that have been linked to cardiovascular health. The objective of this study was to evaluate the effects of fat free peanut flour (FFPF), peanuts, and peanut oil on cardiovascular disease (CVD) risk factors and the development of atherosclerosis in male Syrian golden hamsters. Each experimental diet group was fed a high fat, high cholesterol diet with various peanut components (FFPF, peanut oil, or peanuts) substituted for similar metabolic components in the control diet. Tissues were collected at week 0, 12, 18, and 24. Total plasma cholesterol (TPC), LDL-C, and HDL-C distributions were determined by high-performance gel filtration chromatography, while aortic total cholesterol (TC) and cholesteryl ester (CE) were determined by gas liquid chromatography. Peanuts, peanut oil, and FFPF diet groups had significantly (P < 0.05) lower TPC, non-HDL-C than the control group beginning at about 12 wk and continuing through the 24-wk study. HDL-C was not significantly different among the diet groups. Peanut and peanut component diets retarded an increase in TC and CE. Because CE is an indicator of the development of atherosclerosis this study demonstrated that peanuts, peanut oil, and FFPF retarded the development of atherosclerosis in animals consuming an atherosclerosis inducing diet.

Value-Added Processing of Peanut Skins: Antioxidant Capacity, Total Phenolics, and Procyanidin Content of Spray-Dried Extracts

To explore a potential use for peanut skins as a functional food ingredient, milled skins were extracted with 70% ethanol and filtered to remove insoluble material; the soluble extract was spray-dried with or without the addition of maltodextrin. Peanut skin extracts had high levels of procyanidin oligomers (DP2-DP4) but low levels of monomeric flavan-3-ols and polymers. The addition of maltodextrin during spray-drying resulted in the formation of unknown polymeric compounds. Spray-drying also increased the proportion of flavan-3-ols and DP2 procyanidins in the extracts while decreasing larger procyanidins. Spray-dried powders had higher antioxidant capacity and total phenolics and increased solubility compared to milled skins. These data suggest that spray-dried peanut skin extracts may be a good source of natural antioxidants. Additionally, the insoluble material produced during the process may have increased value for use in animal feed due to enrichment of protein and removal of phenolic compounds during extraction.

Peanut Oil Stability and Physical Properties Across a Range of Industrially Relevant Oleic Acid/Linoleic Acid Ratios

ABSTRACT High oleic cultivars are becoming increasing prevalent in the peanut industry due to their increased shelf life compared to conventional cultivars. High oleic peanuts are typically defined as having oleic acid/linoleic acid (O/L) ratios ≥ 9, whereas most traditional varieties have O/L ratios near 1.5-2.0. In practice, this ratio can vary substantially among commercial material; accordingly, the goal of this study was to gain an understanding of the shelf life and physical properties of 16 model oil blends with O/L ratios systematically prepared from 1.3 to 38.1. Across these samples, % oleic acid, % linoleic acid, refractive index, density and dynamic viscosity were all highly (R2 > 0.99) linearly correlated. Increasing concentrations of oleic acid and corresponding decreases in linoleic acid were associated with decreasing oil density, decreasing refractive index, and increasing viscosity. Oxidative stability index (OSI), an established method for predicting relative oil shelf life, increased mo...

Differences in Development of Oleic and Linoleic Acid in High- and Normal-Oleic Virginia and Runner-Type Peanuts

ABSTRACT A consistent, pure supply of high-oleic (HO) peanuts is important to certain segments of the food industry as it allows for the production of confections and other products with improved s...

Microstructures of Oil Roasted Peanuts (Arachis hypogaea L. cv. VA 98R) as Affected by Raw Moisture Content

Raw runner type peanuts were dried to moisture levels of 4.24 or 6.62 %. Each batch was oil roasted at 160°C in pure peanut oil for the amount of time determined to produce a surface color of 48 on the Hunter L scale. The surfaces of the cotyledons were examined by scanning electron microscopy. Escaping steam caused ruptures in the surfaces during the roasting process. The higher moisture samples had more complex tears to the outer surface as a result of higher amounts of steam escaping from the interior. The interior cell components were found to be more distorted and compacted at a moisture level of 4.24 %. Although it was found that in peanuts, shorter heating times were required to reach the desired color at the higher moisture, the large amount of escaping steam resulted in more surface cell destruction than at the lower moisture. The lower moisture samples appeared to have more interior cell damage. This might have an effect on the retention of oil by the peanuts.

Temperature Effects on Carbohydrates of Hydroponically-Grown Peanuts

Abstract In most years, peanuts from the south-central US have excellent soluble sugar levels for the food industry; however, in some growing seasons high sugar contents are a significant problem associated with roasted color variation. To test the hypothesis that high sugar concentration was related to low temperature extremes, this study evaluated temperature effects on carbohydrate levels in peanuts grown hydroponically. Peanuts were grown with separate pod-zone and shoot-root zone day/night temperatures. Peanut carbohydrate contents were evaluated in seed from pods grown at nighttime pod-zone temperatures of 15, 20, 22, 24 and 28 C. Total carbohydrates were higher in peanuts grown in 15 C pod-zone temperatures compared with those maintained at 28 C. Peanuts harvested at 120 d after planting (DAP) had the highest sucrose contents at 15 and 20 C, the second highest sucrose contents at 22 C, and the lowest sucrose concentration at 24 C. The temperature-induced differential in sucrose contents of 120 DAP ...