Impact of fermentation, drying, roasting and Dutch processing on flavan-3-ol stereochemistry in cacao beans and cocoa ingredients

Abstract

This paper reports a systematic study of the level of flavan-3-ol monomers during typical processing steps as cacao beans are dried, fermented and roasted and the results of Dutch-processing. Methods have been used that resolve the stereoisomers of epicatechin and catechin. In beans harvested from unripe and ripe cacao pods, we find only (-)-epicatechin and (+)-catechin with (-)-epicatechin being by far the predominant isomer. When beans are fermented there is a large loss of both (-)-epicatechin and (+)-catechin, but also the formation of (-)-catechin. We hypothesize that the heat of fermentation may, in part, be responsible for the formation of this enantiomer. When beans are progressively roasted at conditions described as low, medium and high roast conditions, there is a progressive loss of (-)-epicatechin and (+)-catechin and an increase in (-)-catechin with the higher roast levels. When natural and Dutch-processed cacao powders are analyzed, there is progressive loss of both (-)-epicatechin and (+)-catechin with lesser losses of (-)-catechin. We thus observe that in even lightly Dutch-processed powder, the level of (-)-catechin exceeds the level of (-)-epicatechin. The results indicate that much of the increase in the level of (-)-catechin observed during various processing steps may be the result of heat-related epimerization from (-)-epicatechin. These results are discussed with reference to the reported preferred order of absorption of (-)-epicatechin > (+)-catechin > (-)-catechin. These results are also discussed with respect to the balance that must be struck between the beneficial impact of fermentation and roasting on chocolate flavor and the healthful benefits of chocolate and cocoa powder that result in part from the flavan-3-ol monomers.

Dehydrated olive-waste cake as a source of high value-added bioproduct: Drying kinetics, physicochemical properties, and bioactive compounds

“…Some authors reported degradation of flavonoids and tannins (i.e., polymeric forms of flavanoids) as a result of drying treatments (Gu et al, 2004;Kofink et al, 2007;Hurst et al, 2011). Therefore, an optimum combination of drying time/temperature should be established for each product's polyphenolic profile to minimize the degradation of these bioactive compounds during the dehydration leading to recover phenolic compounds and derivatives (Ahmad-Qasem et al, 2013).…”

“…Except, for 80 °C temperature increased the initial content of these compounds. Some authors reported an increase in flavanols during drying process which could be induced by high temperature (Kofink et al, 2007;Hurst et al, 2011). Waste olive cake, in some cases, exceeds the content of several food flavanols, thus this waste could be a rich source of these bioactive compounds (Francene et al, 2003).…”

Changes in the flavan-3-ols, anthocyanins, and flavanols composition of cocoa beans of different Theobroma cacao L. groups affected by roasting conditions

“…During conventional thermal processing, polyphenols are readily degraded and/or become bound to polymer structures [15]. There are several reports in the literature that roasting of cocoa beans led to a decrease in total polyphenol and total flavonoid content [16,17]. The main factor responsible for the degradation of these compounds is high temperature and contact with oxygen during thermal processing.…”

Chemical and Biological Aspects of Extracts from Medicinal Plants with Antidiabetic Effects

“…Polyphenols such as gallocatechin, epicatechin (Figure 2E), epigallocatechin, epigallocatechin gallate, marsupsine, and pterostilbene show an antidiabetic activity [83][84]. Some studies report that polyphenols reduce blood glucose [85].…”