Behavior of starter crops in yogurt-type fermented milk in the presence of washed, cooked and toasted quinoa

Abstract

Lactobacillus bulgaricus and Streptococcus thermophilus are part of the starter cultures used in the production of fermented milks such as yogurt. The behavior of these crops can be modified according to the variation of the substrate on which they feed, temperature conditions or maturation time. On this occasion the initial substrate was modified with the addition of elements that do not come from milk. The presence of non-dairy components in milk can modify the performance of these microorganisms and manifest themselves during fermentation and storage of the finished product. Three types of quinoa flour were mixed; from washed (L), cooked (C) and roasted (T) seed with commercial UHT semi-skimmed milk and fermented to pH 4.6 (same as the control product) which was always regular whole milk. Subsequently, the population of the starter cultures was analyzed until day 21 of refrigerated storage. The samples were carried out in different batches, times and replicates to ensure the veracity of the results, then they were tabulated and adjusted in EXCEL to predict the growth of both bacteria. The results suggest that, in global terms, the control yogurt has a greater microbial population compared to milk fermented with quinoa in any of its presentations.