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United States Department of Agriculture

Agricultural Research Service

Research Project: Improvement & Maintenance of Flavor & Shelf-Life, Functional Characteristics & Biochem/Bioactive Process, & Use of Genetic/Genomic Resource

Location: Market Quality and Handling Research

Title: Peanut Oil Stability and Physical Properties Across a Range of Industrially Relevant O/L Ratios

Authors
item Muddiman, D -
item Sanders, Timothy
item Davis, Jack

Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: April 17, 2013
Publication Date: N/A

Technical 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 better understand the shelf life and physical properties of 16 model oil blends with O/L ratios systematically prepared from 1.3 – 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 concomitant 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/50% R.H. for 24 weeks and periodically sampling these oils to measure peroxide value (PV) and describe oil flavor via sensory analysis. Excellent correlations were observed among: off-flavor (oxidized/cardboard/rancid) development during storage; PV development during storage; O/L ratio and OSI. While viscosity was greatest for high oleic samples when comparing fresh oils, after storage under abusive conditions viscosity increased exponentially with decreasing O/L ratio due to oxidation/polymerization reactions. Overall, these data will aid processors in selection of high O/L peanuts for various food applications and better determine final product shelf life.

Last Modified: 9/20/2014