Production of traditional torba yogurt using lactic acid bacteria isolated from fermented vegetables: Microbiological, physicochemical and sensory properties

The current study aimed to isolate LAB strains naturally present in a traditional fermented vegetable called "Torshi", identify potential probiotics to develop a functional probiotic yogurt, and evaluate the technical, microbiological, physicochemical, and consumer preferences of yogurt. Seven strains of lactic acid bacteria (LAB) were isolated from Torshi and molecularly identified. The results revealed that the isolates were Lactobacillus (L.) plantarum C182, L. gasseri BNR17, L. sakei CJLS03, Pediococcus (P.) acidilactici CCFM18, P. pentosaceus VNK-1, Leuconostoc (Leu.) mesenteroides F27 and Enterococcus (E.) faecalis P190052. Probiotic property assays revealed that L. plantarum C182 survived in acidic conditions and when exposed to 0.3% bile salts, followed by L. sakei CJLS03. The LAB isolates' sensitivity to antibiotics revealed that all isolated strains were resistant to vancomycin, while the L. plantarum C182 and L. sakei CJLS03 strains were found to be susceptible to ampicillin. The surface hydrophobicity test and the autoaggregation factor showed that the highest hydrophobicity was observed in L. plantarum C182 (68.45%) and L. sakei CJLS03 (63.23%). In general, L. plantarum C182 and L. sakei CJLS03 showed better probiotic properties and were used solely and in combination as probiotic LAB to produce the probiotic Iranian traditional yogurt (Torba). Yogurt manufactured with the combination of L. sakei CJLS03 and L. plantarum C182 demonstrated outstanding physicochemical characteristics, significantly restricted Escherichia (E.) coli and Listeria (L.) monocytogenes proliferation, and received the highest consumer preference after 21 days of storage. Overall, including L. sakei CJLS03 and L. plantarum C182 as starter cultures could improve the functionality, microbiological safety, and customer approval of yogurt.