Identifying natural products for improving shelf life of mayonnaise

Abstract

Mayonnaise, is susceptible to oxidation resulting in quality deterioration and the formation of undesirable components such as free radicals and reactive aldehydes. A better understanding of the factors affecting lipid oxidation and ways of retarding oxidation in mayonnaise is essential to improve the shelf life of mayonnaise. Eliminating possible factors, which will reduce the induction period and hasten rancidity, can increase the shelf life of mayonnaise but one of the most effective means of retarding lipid oxidation in mayonnaise is to incorporate antioxidants. Due to the negative effects and perceptions of synthetic antioxidants, there has been a growing interest in using natural antioxidants in food products. Recent studies showed that incorporation of natural antioxidants in mayonnaise could increase its oxidative stability. However, natural antioxidants may exert a negative effect on sensory properties and further studies are needed to identify and overcome this problem. The aim of this project was to study the efficacy of natural antioxidants in inhibiting lipid oxidation in mayonnaise. The evolution of volatile oxidation compounds (VOxCs) in mayonnaise stored at varying temperatures for 92 days was investigated using static headspace extraction and separation by twodimensional gas chromatography/time-of-flight mass spectrometry. Considerable differences in the headspace composition of samples stored at 4, 25 and 38 °C were found due to the different oxidation levels reached. The content of hexanal in mayonnaise at 1-5 days of storage at 38 °C could be used to predict the corresponding compound in mayonnaise at 1-62 days of storage at 25 °C. Some volatile compounds were identified that could be a useful indicator of lipid oxidation of the sunflower oil in the mayonnaise, and by using an antioxidant to reduce these compounds a good oxidative stability could be reached. Interpreting the activity of antioxidants has been difficult due to the complex effect of lipid oxidation conditions and systems. Lipid oxidation process and effect of Butylated hydroxy anisole (BHA) was evaluated in sunflower oil and mayonnaise. The rate of lipid oxidation was higher in mayonnaise compared to bulk oil that could be due to the high surface area of oil that increases lipid interactions with aqueous phase pro-oxidants. BHA, a non-polar antioxidant was more effective in mayonnaise than oil. Differences seen in the efficacy of BHA in oil and mayonnaise could be explained by its Publications included in this thesis