Abstract This study investigates the influence of oleic acid on the stability of peanut oil and explores the role of polyphenols in lipid oxidation. The findings highlight the significant impact of oleic acid content on reducing lipid oxidation in peanuts, while suggesting that polyphenols may not be as critical in preventing rancidity as traditionally believed.
Introduction
Peanuts are widely consumed globally due to their nutritional value and versatility. However, like many oil-rich foods, peanuts are susceptible to rancidity caused by the oxidation of unsaturated fatty acids in their oil, leading to off-flavors and reduced nutritional quality. This research focuses on understanding the factors affecting lipid oxidation in peanuts, specifically examining the roles of oleic acid—a monounsaturated fatty acid known for enhancing shelf life—and polyphenols, which are traditionally considered antioxidants.
Methodology
The study compared three peanut cultivars differing in oleic acid content: normal oleic, mid-oleic, and high oleic. These cultivars were stored under controlled conditions, and their lipid oxidation levels and polyphenolic contents were analyzed over time. The assessment involved measuring peroxide values as an indicator of oxidation and evaluating the polyphenolic compounds present.
Results
Oleic Acid Content and Lipid Oxidation
The results showed that high oleic acid peanuts had a significantly lower rate of lipid oxidation compared to normal and mid-oleic varieties. Even under prolonged storage at elevated temperatures, high oleic peanuts displayed minimal peroxide formation, underscoring the protective role of oleic acid in preserving peanut oil stability. In contrast, the normal and mid-oleic varieties experienced much higher lipid oxidation levels under similar conditions, highlighting the importance of oleic acid in enhancing shelf life.
Polyphenols: A Complex Role
Contrary to expectations, the study found that polyphenols were not as effective in preventing lipid oxidation as previously thought. Although the overall polyphenol content declined over time for all peanut varieties, this decrease did not correlate with the lipid oxidation rates. Notably, specific polyphenolic compounds like p-coumaric acid and its derivatives remained relatively unchanged during storage, suggesting a limited role in mitigating oxidation.