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<abstract> <p>The probiotic potential of lactic acid bacteria (LAB) isolated from Thai traditional fermented food was investigated. Forty-two samples were collected from four markets in Phra Nakhon Si Ayutthaya Province. Out of 50 isolated LAB, 6 (a3, f4, f8, K1, K4 and K9) obtained from pla-ra and bamboo shoot pickle samples showed high tolerance to gastrointestinal tract conditions. These isolates were selected to identify and characterize their probiotic properties. Isolate a3 was identified as <italic>Weissella thailandensis</italic>, isolates f4 and f8 were identified as belonging to <italic>Enterococcus thailandicus</italic> and isolates K1, K4 and K9 were determined as <italic>Limosilactobacillus fermentum</italic>. All six LAB exhibited high autoaggregation ability (93.40–95.01%), while <italic>W. thailandensis</italic> isolate a3 showed potential for coaggregation in almost all the pathogenic bacteria tested. Cell-free supernatant (CFS) obtained from all isolates did not inhibit <italic>Staphylococcus aureus</italic>. CFS derived from <italic>L. fermentum</italic> isolate K4 showed the most efficient antimicrobial activity, in particular against Gram-negative bacteria, while <italic>L. fermentum</italic> isolate K4 presented high surface hydrophobicity in the presence of xylene and n-hexane. All LAB isolates were found to be resistant to clindamycin and nalidixic acid, whereas <italic>E. thailandicus</italic> isolate f8 exhibited resistance to most of the antibiotics tested. <italic>L. fermentum</italic> isolate K4 showed promise as a suitable probiotic candidate for future applications in the food industry due to tolerance to gastrointestinal tract conditions with high surface hydrophobicity and inhibited most of the pathogens tested.</p> </abstract>

In the present work, the supplementation of purple sweet potato flour as a prebiotic at concentrations of 1, 2, and 3% enhanced the probiotic efficacy. These three concentrations of purple sweet potato flour reduced the fermentation time from 4.5 – 5.5 h as compared to the control © recipe (7–5 - 8.0 h). Panellists scored highest overall acceptability for non-fat goat milk yogurt with 1% purple sweet potato flour (S1 recipe). The S1 recipe was selected to evaluate the quality change during storage for 27 days at 4°C. The L* and b* values decreased, whereas the a* value increased. Non-fat goat milk yogurt had low hardness. The supplementation of purple sweet potato flour did not significantly affect yogurt hardness, and reduced the percentage of whey separation during the storage period. Purple sweet potato flour also promoted the survival of Streptococcus thermophilus but reduced viable cells of Lactobacillus delbrueckii subsp. bulgaricus. The S1 recipe was demonstrated as a healthy food with a shelf-life of 27 days, and could appeal to the health-conscious consumers.

At ambient temperature, spring roll wrappers used for roti saimai are highly perishable. Adding organic acids such as 0-0.6% citric acid or vinegar (acetic acid) was evaluated for wrapper pH and sensory acceptability. The Addition of 0.4% citric acid or 0.5% vinegar to spring roll wrappers reduced pH below 4.5 and proved acceptable for panelists. Spring roll wrappers treated with 0.4% citric acid or 0.5% vinegar with/without 0.06% sodium benzoate were packed in two bag types (polypropylene; PP and nylon-linear low density polyethylene; nylon-LLDPE) and stored at ambient and refrigerated temperatures to investigate microbial loads. Vinegar had a greater antimicrobial effect than citric acid, while microbial reduction efficacy increased through the synergistic effects of vinegar and sodium benzoate. Spring roll wrappers treated with 0.5% vinegar with/without 0.06% sodium benzoate were selected to assess changes in quality and shelf-life. Results showed no significant differences in thickness and water activity (aw) values among all conditions. Nylon-LLDPE bags maintained spring roll wrapper moisture content better than PP bags but spring roll wrappers packed in nylon-LLDPE cracked more rapidly than those packed in PP bags during storage at refrigerated temperature. Sodium benzoate also decreased spring roll wrapper springiness. Spring roll wrappers treated with 0.5% vinegar and 0.06% sodium benzoate proved an optimal when packed in PP and nylon-LLDPE bags after storage at refrigerated and ambient temperatures, with shelf-lives of 7 and 13 days respectively.