Physicochemical and microbiological dynamics of the fermentation of the ccn51 cocoa material in three maturity stages

Martha Del Pilar López Hernández,María Denis Lozano Tovar,María Soledad Hernández Gómez,Jenifer Criollo Núñez

doi:10.1590/0100-29452019010

Martha Del Pilar López Hernández, María Denis Lozano Tovar + Show 2 more

Open Access

https://doi.org/10.1590/0100-29452019010

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Abstract

Abstract The physicochemical and microbiological dynamics during the fermentation phase of the CCN51 cocoa material was evaluated in three maturity stages (stage 2: 130-152 days after anthesis (DAA), stage 3: 153-174 DAA, and stage 4: 175-196 DAA). Through the microfermentation technique, the physicochemical variables (pH, titratable acidity, total soluble solids, and fermentation index) were monitored every 24 hours. The microbiological dynamics were evaluated by counting the colony forming units (CFU) in a plaque, quantifying three types of microorganisms (Bacillus, acetic acid bacteria and yeasts). In the three maturity stages assessed, a decrease in the pH of the beans was observed as the fermentation progressed; between 72 and 96 hours after fermentation, the pH of stage 4 beans was different from stages 2 and 3. Simultaneously, an increase in the pH of the pulp was observed without differences between the stages. Brix degrees did not show statistical differences between stages, however, the values of total soluble solids showed that the microorganisms present in stage 3 were more effective in metabolizing these in comparison with those of stages 2 and 4. Regarding the fermentation index, stage 4 reached the maximum value (1.35 ± 0.16) at 120 hours, meanwhile stages 2 and 3 reached it at the end of the fermentation (1.35 ± 0.01 and 1.55 ± 0.29, respectively) at 168 hours. The microbiological dynamics in the three cocoa fruit maturity stages evidenced the absence of lactic acid bacteria and the presence of mesophilic aerobic bacilli. Yeasts were present throughout the fermentation in the three maturity stages, being more favored by stage 2, meanwhile, acetic acid bacteria were favored by stage 3. Outstanding microorganism species were characterized molecularly as Pichia kudriavzevii,Bacillus subtilisBacillus megaterium, and Bacillus tequilensis. Stage 3 showed the best characteristics to obtain good quality cocoa.

Highlights

Cocoa tree (Theobroma cacao L.) is a commercial crop of great economic importance in the world and is the source of the raw material for the manufacture of chocolate (THI et al, 2015, GUTIÉRREZ et al, 2011)
The microbiological dynamics in the three cocoa fruit maturity stages evidenced the absence of lactic acid bacteria and the presence of mesophilic aerobic bacilli
Yeasts were present throughout the fermentation in the three maturity stages, being more favored by stage 2, acetic acid bacteria were favored by stage 3

Summary

Introduction

Cocoa tree (Theobroma cacao L.) is a commercial crop of great economic importance in the world and is the source of the raw material for the manufacture of chocolate (THI et al, 2015, GUTIÉRREZ et al, 2011). In the fermentation process the action of the microorganisms takes place in the pulp surrounding the beans, which is rich in glucose, fructose, and sucrose (total content of 10-15%) and the initial pH is relatively low (pH: 3.3-4.0), mainly due to a high concentration of citric acid (1-3%) (ARDHANA and FLEER, 2003). The fermentation of cocoa is a spontaneous microbiological process; it is known that the microorganisms that initiate the fermentation are yeasts, thanks to the high content of sugars, low pH and the limited availability of oxygen in the pulp (THOMPSON et al, 2013)

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