Development of dairy‐free soybean‐based yoghurt by active dry starter culture from kombucha: an investigation into microencapsulation, curd formation, protein and texture profiles during storage

Abstract

SummaryIncreasing demand for the production and use of non‐dairy products has resulted from the rapid increase of vegetarian and lactose‐intolerant populations. In this study, non‐dairy yoghurt was developed from soybeans using microencapsulated starter culture consisting of Levilactobacillus brevis and Saccharomyces cerevisiae isolated from kombucha based on spray drying and freeze drying techniques using 20% maltodextrin (MD) and gum Arabic‐maltodextrin mixture (GA‐MD) as carriers. Scanning electron microscopy revealed high integrity and effective microbial protection within the carrier matrices, especially for freeze‐dried samples with L. brevis density being in the range of 6.1–6.4 log CFU/g. During 21‐day storage of microcapsules at 4 °C, L. brevis density decreased to 4.4–5.1 log CFU/g for all carriers while GA‐MD was incapable of preserving its viability at 30 °C. Meanwhile, the soybean‐based yoghurt was produced using these four microcapsules as active dry starter culture for the investigation of warm incubation/curd formation and subsequent refrigeration. Regarding warm incubation, in contrast to conventional yoghurt, there was no drop in pH or total acidity over the first 7–8 h of storage, followed by their sudden decline which led to the curd formation in the next hour at pH and total acidity of 5.42–5.75 and 2.29–3.06 g lactic acid/L respectively. Furthermore, GA‐MD samples exhibited more severe syneresis and surface cracks than MD during refrigeration in which the hardness and gumminess of yoghurt increased over time. Electrophoresis results also confirmed the proteolytic activity of lactic acid bacteria and yeast on β‐conglycinin and glycinin fractions of soy proteins.