Studies on Growth Variables, Metabolites and Safety Effect of Lactobacillus Acidophilus, Streptococcus Salivarious Subsp. Thermophilus and Lactobacillus Delbrueckii Subsp. Bulgaricus (As Starter Culture) on Cocos Typical Based Extract During Time-Monitori

The role of Lactic Acid Bacteria (LAB) is vital during bio-processing (fermentation) which could result to desirable nutritional, sensory and safety quality product. This study investigated on growth kinetics variables, metabolites and safety effect of Lactobacillus acidophilus, Streptococcus salivarious subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (as starter culture) on Cocos typical based extract during time-monitoring bio-processing. This was done anaerobically in the bioreactor with optimized timing of 0-72 h at 37 °C, but samples were drawn every 12 h intervals. Specific LAB growth rate was calculated using Monod equation while specific consumption rate of substrates and generation rate of metabolite in the fermenting samples were modeled using Luedeking-Piret equation. The total LAB count (6.36 to 10.54 log10 cfu/ml) and lactic acid concentration (0.07 to 1.74%) increased but pH (6.48 to 4.03), total sugar (20.96 to 10.88%), total soluble sugar (3.01 to 0.17%), total solid (5.98 to 2.81%) and fructo-oligosaccharide (100.05 to 34.31 mg/kg) decreased with increasing fermentation period. At 12 h, higher specific growth rate with the lowest doubling time of 0.22 h-1 and 3.15 h respectively. Both specific fructose and sucrose rate consumed by the lactic acid bacteria were higher at 72 h. Similarly, at 72 h, more lactic acid was produced and the least concentration was observed at 36 h of fermetation period. Zone of inhibition as antibacterial effect of each samples against Escherichia coli, Salmonella typhi and Staphylococcus aureus ranged from 10.11-19.33 mm, 9.13-19.83 mm and 9.89-21.17 mm respectively. It was deduced accordingly that the Cocos typical extracts (at 24 h and 36 h) served as good carbon sources for Lactobacillus acidophilus, Streptococcus salivarious subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) and the production of useful metabolites that could guarantee the prevention of pathogens was enhanced.