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Peanut seed are approximately 50 % oil of which [80 % is either oleic or linoleic acid. The oleic/ linoleic acid (O/L) ratio largely influences oxidative stability and hence peanut shelf life. Traditional peanut seed have O/L ratios near 1.5-2.0; however, many new cultivars are ''high oleic'' with O/L ratios C9. During peanut seed handling, contamination among lots may occur. A cost effective method to rapidly differentiate peanut seed based on O/L ratio is needed across multiple segments of the industry, and measurements of oil density and oil refractive index (RI) were evaluated for this potential. Fatty acid profiles of samples from normal and high oleic seed lots, and blends of these oils, were determined by traditional gas chromatography analysis and this data compared to corresponding oil density and RI measurements. Oleic acid content, linoleic acid content, density and RI were all strongly linearly (R 2 [ 0.98) correlated for oil blends with O/L ratios from *2 to 16. Threshold density or RI values both showed excellent potential for rapidly differentiating samples with an O/L C 9; however, sample volume requirements preclude density measurements on single seed.

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 (R 2 . 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 more than 7X from an O/L of 1.3 to 33.8 and this response was well described by a 2nd order polynomial. Oil stability was also assessed by storing oil blends at 24 C with 50% R.H. for 24 wk and periodically sampling these oils to measure peroxide value (PV) and describe oil flavor via sensory analysis. Excellent correlations were observed among O/L chemistry and off-flavor (oxidized/cardboard/rancid) development during storage, PV development during storage, and OSI. While viscosity was greatest for high oleic samples when comparing fresh oils, after storage under abusive conditions oil viscosity increased exponentially with decreasing O/L ratio due to oxidation/polymerization reactions. Overall, these data and observations will aid processors in selection of high O/L peanuts for various food applications and better determine final product shelf life.

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