Kinetics study on the fermentation of skim milk using freeze-dried probiotic lactic acid bacteria 4E8

Date

6-2016

Degree

Bachelor of Science in Chemical Engineering

College

College of Engineering and Agro-Industrial Technology (CEAT)

Adviser/Committee Chair

Jeanne Michelle T. Valencia

Restrictions

Restricted: Not available to the general public. Access is available only after consultation with author/thesis adviser and only to those bound by the confidentiality agreement.

Abstract

The fermentation kinetics of skim milk using probiotic and proteolytic lactic acid bacteria (LAB) 4E8 was studied using 8, 10, and 12 % (w/v) skim milk. Fermentation of MRS broth using the same organism was also done for comparison. Results showed that the highest biomass yield (7.7 x 10^9 CFU/mL), decrease in substrate consumption (1 718.646 mg/mL), decrease in pH (1.323 units), and increase in percent titratable acidity (0.78 %LA) were obtained in 12 % (w/v) skim milk. Statistically, the biomass yield, decrease in pH, and increase in percent titratable acidity during the fermentation of skin milk solutions and MRS broth were not significantly different from each other. The substrate consumption of LAB 4E8 in MRS broth was significantly different from those in skim milk, except in 8 % (w/v) skim milk. Therefore, any concentration of skim milk can be used a replacement for MRS broth during large-scale fermentation using freeze-dried LAB 4E8. The Moser model (R^2 = 0.9671) best described the fermentation kinetics of LAB 4E8 in skim milk. From the model, the maximum specific growth rate (μmax) and substrate affinity constant (Ks) were 0.41 per hour and 5.46 x 10^10 mg/mL. respectively. The high value of Ks implies that the growth of freeze-dried LAB 4E8 does not slow down at high skim milk concentrations, while n = 3 suggests that there is positive cooperativity that occurred during fermentation of skim milk.

Language

English

Location

UPLB College of Engineering and Agro-Industrial Technology (CEAT)

Call Number

LG 993.5 2016 E62 /C33

Document Type

Thesis

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