The fermentation of cocoa seeds envolves microbial processes and the action of enzymes. To identify the possible differences in the cocoa fermentation process, with regards to proteolysis, this study has the objective of determining protease activity (under predetermined conditions) and its isoenzymes in two cocoa cultivars (PH-16 and HRT-1188) in different cocoa fermentation times, in addition to establishing the microbial load (molds and yeasts and aerobic mesophilic). Protease and its isoenzymes were extracted and partially purified and the enzymatic activities determined by spectrophotometry. The results showed that the proteases activity was higher at 66h of fermentation for both cultivars. When the isoenzymes activity was evaluated, the results demonstrated similar activity behavior for both cultivars, with regards to the isoenzymes aminopeptidase and carboxypeptidase, although the behavior of the endoprotease isoenzyme activity proved to be a little different for TSH-1188 cultivar. Concerning microbiological analyses, the results indicate that the period after molds and yeast counting reduction is consistent with the period of protease activity increase.Keywords: cocoa; proteolysis; aminopeptidase; carboxypeptidase; endoprotease.Practical Application: This study evaluates proteases enzymatic activity and their isoenzymes under predetermined conditions in the cocoa fermentation process, highlighting the importance of proteolysis in the formation of precursors of cocoa flavour and therefore chocolate.
The effects of aeration and agitation on the properties and production of xanthan gum from crude glycerin biodiesel (CGB) by Xanthomonas campestris mangiferaeindicae 2103 were investigated and optimized using a response surface methodology. The xanthan gum was produced from CGB in a bioreactor at 28 °C for 120 h. Optimization procedures indicated that 0.97 vvm at 497.76 rpm resulted in a xanthan gum production of 5.59 g L(-1) and 1.05 vvm at 484.75 rpm maximized the biomass to 3.26 g L(-1). Moreover, the combination of 1.05 vvm at 499.40 rpm maximized the viscosity of xanthan at 0.5% (m/v), 25 °C, and 25 s(-1) (255.40 mPa s). The other responses did not generate predictive models. Low agitation contributed to the increase of xanthan gum production, biomass, viscosity, molecular mass, and the pyruvic acid concentration. Increases in the agitation contributed to the formation of xanthan gum with high mannose concentration. Decreases in the aeration contributed to the xanthan gum production and the formation of biopolymer with high mannose and glucose concentrations. Increases in aeration contributed to increased biomass, viscosity, and formation of xanthan gum with greater resistance to thermal degradation. Overall, aeration and agitation of CGB fermentation significantly influenced the production of xanthan gum and its properties.
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