Production and evaluation of probiotic red grape juice by Latobacillus acidophilus LA5, and Lactobacillus casei

Production of probiotic non-dairy food has a great attention. The objective of this study was to investigate the survival of Lactobacillus acidophilus type LA-5 and L. casei type 431 in red grape juice during storage at refrigerated condition for 4 weeks. Red grape juice with Brix 15 prepared and pasteurized at 80 ºC for 4 min. A preliminary fermentation of juice containing both bacteria was done at 37 ºC for 3 days was done and all treatments were maintained at 4 ºC for 4 weeks. Survival of bacteria, Brix, titrable acidity, pH, and total sugar contents were measured during fermentation and storage period. The results showed that after 4 weeks of storage at 4 ºC, the viable cell counts of L. acidophilus were stabilized at 2.1×108 cfu/mL, while L. casei did not survive the low pH and high acidity conditions in red grape juice and declined to its lowest level as 5 ×104 cfu/mL. The results also showed that L. acidophilus made increase in acidity during the stages of fermentation (P≥ 0.05) and the storage time and the sugar consumption and reducing of Brix was also higher in L. acidophilus compared with L. casei. It is concluded that red grape juice could serve as a raw material for the production of probiotic juice by L. acidophilus as compared by incorporating L. casei.