AUTHOR=Tsao Chieh-Hsi , Chang Chih-Wei , Ho Yu-Chi , Chuang Yung-Kun , Lee Wei-Ju 

TITLE=Application of OXITEST for Prediction of Shelf-Lives of Selected Cold-Pressed Oils

JOURNAL=Frontiers in Nutrition

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2021.763524

DOI=10.3389/fnut.2021.763524

ISSN=2296-861X

ABSTRACT=<p><bold>Introduction:</bold> Due to the enhanced awareness of consumers concerning healthy foods, homemade expeller-pressed oils have become popular worldwide. However, an extended storage period may lead to oxidization of the oil and exposure to hazardous byproducts by consumers.</p><p><bold>Methods:</bold> In this study, 10 pressed oil samples prepared from common oilseeds using a small-scale expeller oil press were analyzed by OXITEST with a sample amount of 5 g of oil and an oxygen pressure of 800 kPa under accelerated conditions for shelf-life projections. The oil properties were investigated, including the recovery, smoke point, acid value, iodine value, “fatty acid composition, and contents of pigments and tocopherols”.</p><p><bold>Results:</bold> The autoxidation reaction of various expeller-pressed oils under an accelerated testing system followed zero-order Arrhenius kinetics (<italic>R</italic><sup>2</sup> &gt; 0.99). Shelf-lives of the pressed oils at 25°C were estimated by extrapolation to range 105~1,089 days. The obtained shelf-lives were significantly correlated with log induction period (IP) values (<italic>r</italic> &gt; 0.81, <italic>p</italic> &lt; 0.05) and unsaturated fatty acids (UFAs) (<italic>r</italic> &lt; −0.69, <italic>p</italic> &lt; 0.05), but not with the iodine value, acid value, or smoke point. Scatter diagrams between shelf-lives and UFAs suggested that these pressed oils could be grouped by two linear regression curves (<italic>r</italic> &gt; 0.98, <italic>p</italic> &lt; 0.05). The predictive equations using multiple linear regression are presented herein, with predictor variables of UFAs and an unspecified item involving potential influencing factors such as tocopherol contents (<italic>r</italic> &gt; 0.88, <italic>p</italic> &lt; 0.05).</p><p><bold>Conclusions:</bold> Our findings first revealed that the UFA portion was partially correlated with the shelf-lives of selected expeller-pressed seed oils as estimated by the OXITEST. The derived equations can be applied for shelf-life predictions of expeller-pressed oils stored under dark ambient conditions based on the fatty acid profile.</p>