Correlation between Microbial Population and Oxidative Stability of the Yogurt-Based Tzatziki Salad

Tzatziki is a deli salad widely consumed in the Eastern Mediterranean and Balkan countries, and it is acknowledged for its health benefits. So far, it is proved to exhibit extreme resistance to microbial spoilage by (pathogenic) microorganisms and microbial self-stabilization, but no research was carried out regarding its oxidative stability despite the fact that it contains a large amount of lipids. In this study, the factor that affects the oxidative stability of tzatziki was exploited. Different samples of tzatziki salad were prepared and stored for 16 or 27 days, depending on the conducted experiment. They varied in the type of yogurt (set yogurt or traditional Greek-style yogurt), the type of oil (olive oil or soybean oil), and the addition or not of preservatives, garlic, and cucumber. Samples were analyzed in terms of oxidative stability (by the Rancimat method), colony-forming units, and tocopherol content throughout the storage period. Among the examined parameters, no correlation between the tocopherol content and oxidative stability was recorded. However, a strong correlation between the microbial population and the oxidative stability was recorded. Therefore, this correlation can be used to prepare tzatziki salads with increased shelf life and decreased flavor deterioration (due to oxidation). Moreover, such correlations should be further exploited for other foods so as to promote their stability.