Oil Characteristics of Peanut Fruit Separated by a Nondestructive Maturity Classification Method

Abstract

A nondestructive peanut pod maturity classification method, Pod Maturity Profile (PMP), based on visual examination of the color and structural characteristics of pod mesocarp after partial removal of pod exocarp, was used to separate freshly harvested peanut pods into maturity classes. The separations made nondestructively were compared with those made by a method involving the examination of internal pericarp and testa characteristics. The groups separated by the two methods were closely related. In oil from the PMP classes, color decreased, free fatty acid content decreased, iodine value remained approximately constant, and oven stability of the extracted oil increased with increasing maturity. Total oil contents and fatty acid profiles had consistent but more complex relationships with maturity. The data indicate that the PMP method allows consistent and reproducible classification of peanut fruit maturity.

Chemical Composition of Arachis hypogaea L. Subsp. hypogaea Var. hirsuta Peanuts1

“…The normal range for oil content in peanuts is 44 to 56% with a mean of 50% (Cobb and Johnson, 1973). One explanation for the low oil content in these two samples is that they contained higher percentages of immature seeds, which have lower oil content (Sanders et al, 1982). We believe this is not the case since the levels of arginine, another indicator of maturity , found in these samples compared favorably with the levels in the control samples as dis cussed below.…”

“…Higher O/L ratios generally relate to increased oil stability and increased shelf life of peanut products (Fore et al, 1953). The O/L ratio increases with peanut maturity Sanders et al, 1982) and is influenced by cultivar and environmental factors. Higher O/L ratios are pro- duced at higher growth temperatures (Holaday and Pearson, 1974;Brown etal, 1975).…”

“…The relationship of peanut composition to flavor and shelf life has been established directly in several studies and indirectly in studies relating flavor and shelf life to maturity (Sanders et al, 1982;Sanders et al, 1989;Bett and Boylston, 1992). Oil components, free amino acids, sugars, pro-and antioxidants, and other components have been implicated in flavor or shelf life of peanuts.…”

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

“…To make the study more manageable, data presented here are only for the first (65 DAP for virginia-type, 71 DAP for runner-type), mid-point (115 DAP for virginia-type, 106 DAP for runner-type) and harvest date (148 DAP for virginia-type, 158 for runnertype) samplings. Pod weight and seed weight have been shown to increase as the growing season progresses (Pattee et al, 1977, Sanders et al, 1982, McNeill and Sanders, 1996. Bailey is a medium to large-seeded virginia-type peanut and 'Spain' is a virginia-type that has very large pods.…”

“…The indeterminate flowering trait of the peanut is responsible for the range of pod maturities and seed sizes observed at peanut harvest. In normal peanut development, the seed rapidly accumulates carbohydrate and near mid-maturity, lipid accumulation becomes the dominant storage process (Ketring et al, 1982, Sanders et al, 1982. The study reported here describes the development of the O/L ratio in NO and HO seed for both virginia-and runner-type cultivars as a function of individual seed fresh weight in order to document the physiological expression of the HO trait over the course of peanut seed growth.…”