Determination of the effects of propolis ethanolic extract on some properties of fruit yoghurt during storage

Abstract

Aims: The aim of this study was to determine the chemical and microbiological properties of propolis ethanolic (PEE) extract added fruit yoghurt during a storage period.Methods and Results: PEE (in different ratios: 0.01%, 0.03%, 0.10%, 0.20% and control=0.00%) added fruit yoghurt was stored at +4 °C for 28 days. Dry matter, protein content, pH, titratable acidity, DPPH inhibition and total phenols were analysed on the first and 28th days of storage. Microbiological analyses of yoghurts were also carried in first and seventh days. Titratable acidity values were increased while pH values decreased at the end of the storage period in all samples. DPPH inhibition and total phenols amounts were increased in line with the amount of added PEE. It was observed that added propolis amount did not affect total aerobic mesophilic flora (p>0.05). During the storage period, lactic acid bacteria (LAB) increased in all the groups and the control group had the highest bacteria count. The number of yeast and mould increased in all the groups.Conclusions: Our results indicated that PEE does not adversely influence the mechanism of yoghurt formation. We also found that propolis increased the nutritional benefits by increasing the antioxidant capacity of yoghurt.Significance and Impact of the Study: In this study PEE has been added to fruit yoghurts in different proportions. It has been observed that the nutritional properties and antioxidant content of yoghurts have increased. It was considered that propolis can be used as a natural food additive.