The probiotic yogurt market is growing due to the potential benefits that probiotics provide to the host, including the relief of lactose intolerance symptoms, easing diarrhea, and improving immune system. However, probiotics are sensitive, both processing conditions and high acidity of yogurt can reduce probiotic viability. The objective of this study was to use bigel technology, a novel entrapment system, to improve the survival of probiotics incorporated into yogurt. Bigels were formulated by blending oleogel emulsion (OGE) and hydrogel (HG). In this study, probiotic bigels were prepared by homogenizing OGE (10% wt/wt soy lecithin, 10% wt/wt stearic acid, 10% wt/wt milk and soybean oil) and HG (25% wt/wt whey protein concentrate and deionized water) followed by incorporating Lactobacillus acidophilus and Bifidobacterium lactis suspended in milk. Four samples were prepared: yogurt with 18% wt/wt probiotic bigels with and without agitation, yogurt without probiotics and bigel, yogurt with only probiotics (no bigel). Probiotic viability at 4°C was monitored via plate counts for six weeks. The results showed the growth rate of L. acidophilus and B. lactis in bigel was higher and decreased slower than those not in the bigel matrix, which indicated probiotics can be efficiently entrapped in bigel systems and the presence of phospholipids enhanced probiotic viabilities in yogurt. No significant difference was found between agitated and non-agitated samples, which indicated the bigel structure did not affect the probiotic viabilities in yogurt. This approach shows a promising future for bigel applications in commercial yogurt production to improve the efficacy of probiotics.
