Effect of goji berries and honey on lactic acid bacteria viability and shelf life stability of yoghurt

Abstract

The probiotic properties and the viability of lactic acid bacteria of fermented dairy products can be improved by addition of bioactive compounds originating from natural sources (e.g. goji berries). This study aimed to evaluate how goji berries and honey affect the sensorial quality of yoghurt, the chemical properties, the viability of lactic acid bacteria (LAB) and the concurrent microflora development. Two types of yoghurts (yoghurt with goji berries and yoghurt with honey and goji berries) were developed. The addition of honey affected the entire yoghurt microflora including LAB, manifesting bactericidal effect. The addition of goji berries maintained the viability of LAB at probiotic levels (106-107 log CFU/ml) during 21 days of storage; compared to classic yoghurt, LAB viability decreased during storage at 103 log CFU/ml. Goji berries also improved sensory acceptance of consumers. The results obtained in this study collect information that enables the use of goji berries as enhancer of probiotic levels in yoghurt, while honey can provide bacteriostatic/bactericidal effect for contaminants.