Characterization of polyphenol oxidase in two cocoa (Theobroma cacao L.) cultivars produced in the south of Bahia, Brazil

Abstract

The reactions leading to the formation of precursors of chocolate flavor are performed by endogenous enzymes present in the cocoa seed. Polyphenol oxidase (PPD) presence and activity during fermentation of cocoa beans is responsible for the development of flavor precursors and is also implicated in the reduction of bitterness and astringency. However, the reliability of cocoa enzyme activities is complicated due to variations in different genotypes, geographical origins and methods of fermentation. In addition, there is still a lack of systematic studies comparing different cocoa cultivars. So, the present study was designed to characterize the activity of PPD in the pulp and seeds of two cocoa cultivars, PH 16 and TSH 1188. The PPD activity was determined spectrophotometrically and characterized as the optimal substrate concentration, pH and temperature and the results were correlated with the conditions during the fermentation process. The results showed the specificity and differences between the two cocoa cultivars and between the pulp and seeds of each cultivar. It is suggested that specific criteria must be adopted for each cultivar, based on the optimal PPD parameters, to prolong the period of maximum PPD activity during fermentation, contributing to the improvement of the quality of cocoa beans.Keywords: cocoa; fermentation; enzyme activity; chocolate.Practical Application: To obtain knowledge for future technological interventions during fermentation for the improvement of the quality of raw material in the production of monovarietal chocolates.

Changes in the composition and content of polyphenols in chocolate resulting from pre-treatment method of cocoa beans and technological process

“…The effect of the geographical origin of cocoa beans was confirmed by Macedo et al [49], who demonstrated the activity of cocoa enzymes to depend on beans genotype and geographical origin and on the applied parameters of the fermentation process.…”

“…50 °C [54]. Macedo et al [49] designed a study to explain the activity of polyphenolic oxidase in the pulp and beans of two cocoa types. Results of this study demonstrated specificity and differences between the two analyzed varieties as well as between the pulp and beans of each type.…”

“…Results of this study demonstrated specificity and differences between the two analyzed varieties as well as between the pulp and beans of each type. These authors suggested that special grades should be adopted for each varieties based on optimal parameters to extend the period of the maximum activity of polyphenolic oxidase during the fermentation process, which would contribute to improving of cocoa beans quality and, consequently, of chocolate quality [49].…”

Insight of Polyphenol Oxidase Enzyme Inhibition and Total Polyphenol Recovery from Cocoa Beans

“…Affinities of PPO for catechins obtained in this study were quite similar to that reported by Wuyts et al [ 39 ] and Ho [ 40 ] with K m of 1.2 and 2.1 mM, respectively, as well as for (−)-epicatechin with K m equal to 0.65 and 1.18 mM according to Liu et al [ 41 ] and Martinez-Cayuela et al [ 42 ], respectively. The kinetic constant for catechol was 0.61 mM, similar to the value range from 0.18 to 0.97 mM for cocoa pulp and bean, respectively [ 1 ], but different from other plant samples, with values ranging from to 203.8 mM [ 2 , 28 , 43 ], which can be due to method of extraction, nature of the subtrate, and method of measurement.…”

“…Precursors of chocolate flavor are usually obtained through enzymatic and non-enzymatic reactions, in which polyphenol oxidase, invertase, and protease are the most important enzymes [ 1 ]. Polyphenol oxidase (PPO) is a major copper enzyme [ 2 ], also known as catechol oxidase, tyrosinase, and so forth [ 3 ], and is the most important deteriorative enzyme that accelerates oxidation and degradation of polyphenols and their derivatives [ 4 ].…”