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 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 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/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 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.

Peanut (Arachis hypogaea L.): A Prospective Legume Crop to Offer Multiple Health Benefits Under Changing Climate

“…Peanut seeds contain carbohydrates (105% to 20%), protein (16% to 36%), and oil (36% to 54%) as major constituents (Davis et al., ). They also contain many important functional components including coenzyme Q 10 (Pravst, Žmitek, & Žmitek, ), arginine, and polysterols, which make it a functional food (Akhtar, Khalid, Ahmed, Shahzad, & Suleria, ; Francisco & Resurrecion, ).…”

“…An important aspect of the peanut oil is the relative ratios of different fatty acids, which dramatically change with maturity (Pattee, Johns, Singleton, & Sanders, ; Sanders, ). Typically, a majority of peanut genotypes contain 36% to 67% oleic and 15% to 46% linoleic acid resulting in O/L ratios ranging from 1.19 to 4.46 (Davis et al., ; Norden, Gorbet, Knauft, & Young, ). Rapid changes taking place in climate can also influence the oil contents and its composition.…”

Relationship of chemical properties of different peanut varieties to peanut butter storage stability

“…Thus, the oleic/linoleic ratio (O/L) for Kainong 17-15 was 19.82:1. In addition to nutritional properties, Davis et al (2016) and Janick (2014) evaluate peanuts and peanut products by the stability index (SI), which is O/L ratio. In addition, other researchers reported that the high stability index implies a good compositional quality of the product and can ensure better shelf life (Dhamsaniya et al 2012).…”

Trans-Esterification Between Citric Acid and Peanut Oil at Low pH and Ambient Temperature Catalyzed by Citric Acid and Sulfuric Acid Protonic Acid-H<sup>+</sup>

“…Other oils and fats characteristics are also fire points, flash points [23], refractive index. Indeed, it was established a correlation between peanuts refractive index, peanuts oleic acid rate and peanuts linoleic acid rate such as increasing concentrations of oleic acid and corresponding of decreases in linoleic acid were associated with decreasing oil density, decreasing refractive index, and increasing viscosity [29]. The following table 4 showed the Malagasy peanuts compositions.…”