Study of the Oxidative Stability of Oleogels Structured with Beeswax Fractions

Abstract

Combining the beeswax fractions is an effective way of structuring edible oils. However, their effect on oleogel oxidative stability is still not studied. Thus, the study on the influence of beeswax and combinations of its fractions on the edible oleogels oxidation was the objective of this research.Four fractions of beeswax (A, B, C, D) were isolated using preparative flash-chromatography and characterized by TLC and HPLC-ELSD. Sunflower oil was used to prepare oleogels (at 90 °C for 30 minutes) with a 6% of gelator. The fatty acid composition was evaluated by GC. The samples were stored at 35°C for 20 days, monitoring the oxidation using: PV, AV, CDV, TOTOX, HS-SPME-GC-MS. The induction period was determined using the OXITEST reactor.We have shown that fraction A contained hydrocarbons ( >99%); B - monoesters ( >95%); C - wax esters ( >66%), alcohols ( >29%), and free fatty acids ( >4%); D - alcohols ( >49%), free fatty acids ( >40%) and wax esters ( >10%). Combinations of A+B, A+B+C, and A+B+D gelators were made using fractions in equal amounts. The fatty acid composition of freshly prepared oleogels and oil didn't differ (p >0.05). Sunflower oil had the best oxidative stability among all samples. The A+B-based oleogel had the highest oxidative stability among the oleogels. Hexanal is shown to be the main volatile organic compound formed during the oxidation of sunflower oil. The volatile compounds profile of the oleogels also included ketones, alcohols, and terpenes. Beeswax-based oleogel had the lowest induction period, which indicates the presence of prooxidant components. A close correlation was found between the oxidation rate of oleogels and the content of free fatty acids (r2=0.8195) in the gelator.This study shows that the use of beeswax fractions, compared to beeswax itself, results in fat-containing products with higher oxidation stability.