Optimization of inoculation rate of selected microorganisms in a simulated medium for cacao (Theobroma cacao L.) fermentation using response surface methodology

Date

7-2015

Degree

Bachelor of Science in Agricultural Biotechnology

College

College of Agriculture and Food Science (CAFS)

Adviser/Committee Chair

Lotis E. Mopera

Abstract

A starter culture formulation containing Hanseniaspora sp., Lactobacillus plantarum and Gluconobacter sp., screened for acid, heat, carbon source and ethanol tolerance in a previous study, was optimized using a simulated medium by evaluating the effect of inoculant concentration on some parameters of cacao fermentation quality (pH, titratable acidity and % sugar consumption). The criteria set for the desired starter culture was the lowest inoculant concentrations that could give the highest of the responses. The simulated cacao pulp fermentation was similar to natural fermentation, based on parameters of pH, titratable acidity, % ethanol and % sugar consumption. The highest % sugar consumption (91.8%) was observed at high levels of the lactic acid bacteria (LAB) inoculant. Lower levels of LAB inoculant were not able to attain this level of sugar consumption, even when inoculated with high concentrations of yeasts inoculum. This implied the importance of a high level of LAB inoculum. The model was not found to be good predictors for pH and titratable acidity as responses, though the highest titratable acidity was observed even when the lowest level of acetic acid bacteria (AAB) was inoculated. in the optimization run, the lowest inoculant concentrations that could give the maximum of the responses were found to be 4 log CFU/ml for yeast, 8.69 log CFU/ml for LAB, and 3 log CFU/ml for AAB. Te study suggests that AAB may not need to be inoculated when fermenting actual cacao beans, and that inoculating a high concentration of LAB inoculant, while inoculating yeast at a low level, is sufficient for obtaining a high oercent sugar consumption.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2015 A127 S24

Document Type

Thesis

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