PROCESS OPTIMIZATION OF COCOA BEANS FOR THE DEVELOPMENT OF POLYPHENOL RICH CHOCOLATE
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Date
2022
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Abstract
A study was carried out with the objective to retain maximum polyphenol
during fermentation and other processing steps of cocoa bean for chocolate
production. The native microflora such as yeast, lactic acid bacteria and acetic acid
bacteria were isolated and identified during natural fermentation in Coimbatore,
Salem and Dharmapuri districts of Tamil Nadu. The isolates of yeast Saccharomyces
cerevisiae, Kluyveromyces marxianus, Pichia kudriavzevii and lactic acid bacteria
isolates Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus
fermentum, and acetic acid bacteria isolates Gluconobacter oxy dans, Acetobacter
aceti, Acetobacter pasteurianus were screened after morphological, biochemical and
molecular techniques for accelerated fermentation of cocoa beans. Nine treatment
combinations were formulated by orthogonal array method, out of which Treatment
T6 containing Kluyveromyces marxianus, Lactobacillus fermentum, Acetobacter
pasteurianus showed maximum catechin, epicatechin, total polyphenol and total
flavonoid of 7.612±0.02 mg/g, 8.111±0.06 mg/g, 66.64±0.17 mg/g of GAE and
35.323±0.18 mg/g of QE respectively. The physicochemical parameters such as
fermentation index, cut score, pH and temperature showed desirable values on the
third day of fermentation thus decreasing days of fermentation with improved
combinations of starter culture. The next level was drying of cocoa beans which was
carried out in direct sun drying, tray drying and vacuum drying with different drying
temperatures for tray and vacuum drying. Among the drying methods, vacuum drying
at 60°C (VT6) depicted higher polyphenol and flavonoids content with required
moisture content to produce chocolate. Tray drying at 70°C (TT6) showed best results
among tray drying treatments and was also chosen as alternate drying method for
farmers ease of adaptation. After drying, roasting and conching conditions determine
the amount of polyphenols in cocoa beans. Response surface methodology (RSM)
tool was utilized to determine desired solution using roasting temperature, roasting
time and conching time. For VT6 the optimum roasting temperature, roasting time
and conching time were found to be 135.5°C, 18 minutes and 4.5 hours respectively
and 136.5 °C, 18 minutes and 3 hours respectively for TT6. In order to predict the
storage stability of the chocolate, the parameters such as sensory evaluation, water
activity, microbial count, total phenol, total flavonoid of the prepared dark chocolate
from TT6, VT6 treatment for 150 days was analyzed. Both VT6 and TT6 showed
longer shelf life with overall sensory acceptability while VT6 resulted in higher
polyphenol content retention.