Loss of Native Flavanols during Fermentation and Roasting Does Not Necessarily Reduce Digestive Enzyme-Inhibiting Bioactivities of Cocoa

Theobroma cacao and Theobroma grandiflorum: Botany, Composition and Pharmacological Activities of Pods and Seeds

Cocoa and cupuassu are evergreen Amazonian trees belonging to the genus Theobroma, with morphologically distinct fruits, including pods and beans. These beans are generally used for agri-food and cosmetics and have high fat and carbohydrates contents. The beans also contain interesting bioactive compounds, among which are polyphenols and methylxanthines thought to be responsible for various health benefits such as protective abilities against cardiovascular and neurodegenerative disorders and other metabolic disorders such as obesity and diabetes. Although these pods represent 50-80% of the whole fruit and provide a rich source of proteins, they are regularly eliminated during the cocoa and cupuassu transformation process. The purpose of this work is to provide an overview of recent research on cocoa and cupuassu pods and beans, with emphasis on their chemical composition, bioavailability, and pharmacological properties. According to the literature, pods and beans from cocoa and cupuassu are promising ecological and healthy resources.

Underlying evidence for the health benefits of fermented foods in humans

Fermented foods (FFs) have been a part of our diets for millennia and comprise highly diverse products obtained from plants and animals all over the world. Historically, fermentation has been used to preserve food and render certain raw materials edible. As our food systems evolve towards more sustainability, the health benefits of FFs have been increasingly touted. Fermentation generates new/transformed bioactive compounds that may occur in association with probiotic bacteria. The result can be specific, advantageous functional properties. Yet, when considering the body of human studies on the topic, whether observational or experimental, it is rare to come across findings supporting the above assertion. Certainly, results are lacking to confirm the widespread idea that FFs have general health benefits. There are some exceptions, such as in the case of lactose degradation via fermentation in individuals who are lactose intolerant; the impact of select fermented dairy products on insulin sensitivity; or the benefits of alcohol consumption. However, in other situations, the results fail to categorically indicate whether FFs have neutral, beneficial, or detrimental effects on human health. This review tackles this apparent incongruity by showing why it is complex to test the health effects of FFs and what can be done to improve knowledge in this field.

Antiviral, Cytotoxic, and Antioxidant Activities of Three Edible Agaricomycetes Mushrooms: Pleurotus columbinus, Pleurotus sajor-caju, and Agaricus bisporus

In this study, we investigated aqueous extracts of three edible mushrooms: Agaricus bisporus (white button mushroom), Pleurotus columbinus (oyster mushroom), and Pleurotus sajor-caju (grey oyster mushroom). The extracts were biochemically characterized for total carbohydrate, phenolic, flavonoid, vitamin, and protein contents besides amino acid analysis. Triple TOF proteome analysis showed 30.1% similarity between proteomes of the two Pleurotus spp. All three extracts showed promising antiviral activities. While Pleurotus columbinus extract showed potent activity against adenovirus (Ad7, selectivity index (SI) = 4.2), Agaricus bisporus showed strong activity against herpes simplex II (HSV-2; SI = 3.7). The extracts showed low cytotoxicity against normal human peripheral blood mononuclear cells (PBMCs) and moderate cytotoxicity against prostate (PC3, DU-145); colorectal (Colo-205); cecum carcinoma (LS-513); liver carcinoma (HepG2); cervical cancer (HeLa); breast adenocarcinoma (MDA-MB-231 and MCF-7) as well as leukemia (CCRF-CEM); acute monocytic leukemia (THP1); acute promyelocytic leukemia (NB4); and lymphoma (U937) cell lines. Antioxidant activity was evaluated using 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging, 2,2′-Azinobis-(3-Ethylbenzthiazolin-6-Sulfonic Acid) ABTS radical cation scavenging, and oxygen radical absorbance capacity (ORAC) assays. The three extracts showed potential antioxidant activities with the maximum activity recorded for Pleurotus columbinus (IC₅₀ µg/mL) = 35.13 ± 3.27 for DPPH, 13.97 ± 4.91 for ABTS, and 29.42 ± 3.21 for ORAC assays.

Proteome Analysis and In Vitro Antiviral, Anticancer and Antioxidant Capacities of the Aqueous Extracts of Lentinula edodes and Pleurotus ostreatus Edible Mushrooms

In this study, we examined aqueous extracts of the edible mushrooms Pleurotus ostreatus (oyster mushroom) and Lentinula edodes (shiitake mushroom). Proteome analysis was conducted using LC-Triple TOF-MS and showed the expression of 753 proteins by Pleurotus ostreatus, and 432 proteins by Lentinula edodes. Bioactive peptides: Rab GDP dissociation inhibitor, superoxide dismutase, thioredoxin reductase, serine proteinase and lectin, were identified in both mushrooms. The extracts also included promising bioactive compounds including phenolics, flavonoids, vitamins and amino acids. The extracts showed promising antiviral activities, with a selectivity index (SI) of 4.5 for Pleurotus ostreatus against adenovirus (Ad7), and a slight activity for Lentinula edodes against herpes simplex-II (HSV-2). The extracts were not cytotoxic to normal human peripheral blood mononuclear cells (PBMCs). On the contrary, they showed moderate cytotoxicity against various cancer cell lines. Additionally, antioxidant activity was assessed using DPPH radical scavenging, ABTS radical cation scavenging and ORAC assays. The two extracts showed potential antioxidant activities, with the maximum activity seen for Pleurotus ostreatus (IC50 µg/mL) = 39.46 ± 1.27 for DPPH; 11.22 ± 1.81 for ABTS; and 21.40 ± 2.20 for ORAC assays. This study encourages the use of these mushrooms in medicine in the light of their low cytotoxicity on normal PBMCs vis à vis their antiviral, antitumor and antioxidant capabilities.

Fermentation transforms the phenolic profiles and bioactivities of plant-based foods

Phenolics are a group of compounds derived from plants that have displayed potent biological activities and health-promoting effects. Fermentation is one of the most conventional but still prevalent bioprocessing methods in the food industry, with the potential to increase phenolic content and enhance its nutritive value. This review details the biotransformation of different classes of phenolics (hydroxycinnamic and hydroxybenzoic acids, flavonoids, tannins, stilbenoids, lignans, alkylresorcinols) by various microorganisms (lactic acid bacteria, yeast, filamentous fungi) throughout the fermentation process in plant-based foods. Several researchers have commenced the use of metabolic engineering, as in recombinant Saccharomyces cerevisiae yeast and Escherichia coli, to enhance the production of this transformation. The impact of phenolics on the metabolism of microorganisms and fermentation process, although complex, is reviewed for the first time. Moreover, this paper highlights the general effect of fermentation on the food's phenolic content, and its bioaccessibility, bioavailability and bioactivities including antioxidant capacity, anti-cancer, anti-diabetic, anti-inflammation, anti-obesity properties. Phenolics of different classes are converted into compounds that are often more bioactive than the parent compounds, and fermentation generally leads to a higher phenolic content and antioxidant activity in most studies. However, biotransformation of several phenolic classes is less studied due to its low concentration and apparent insignificance to the food system. Therefore, there is potential for application of metabolic engineering to further enhance the content of different phenolic classes and bioactivities in food.

Comparative assessment of phenolic bioaccessibility from 100% grape juice and whole grapes

Concord and Niagara grape juice have comparable or greater absolute bioaccessibility of major classes of phenolic compounds compared to masticated whole grapes.

Flavanol Polymerization Is a Superior Predictor of α-Glucosidase Inhibitory Activity Compared to Flavanol or Total Polyphenol Concentrations in Cocoas Prepared by Variations in Controlled Fermentation and Roasting of the Same Raw Cocoa Beans

Raw cocoa beans were processed to produce cocoa powders with different combinations of fermentation (unfermented, cool, or hot) and roasting (not roasted, cool, or hot). Cocoa powder extracts were characterized and assessed for α-glucosidase inhibitory activity in vitro. Cocoa processing (fermentation/roasting) contributed to significant losses of native flavanols. All of the treatments dose-dependently inhibited α-glucosidase activity, with cool fermented/cool roasted powder exhibiting the greatest potency (IC₅₀: 68.09 µg/mL), when compared to acarbose (IC₅₀: 133.22 µg/mL). A strong negative correlation was observed between flavanol mDP and IC₅₀, suggesting flavanol polymerization as a marker of enhanced α-glucosidase inhibition in cocoa. Our data demonstrate that cocoa powders are potent inhibitors of α-glucosidase. Significant reductions in the total polyphenol and flavanol concentrations induced by processing do not necessarily dictate a reduced capacity for α-glucosidase inhibition, but rather these steps can enhance cocoa bioactivity. Non-traditional compositional markers may be better predictors of enzyme inhibitory activity than cocoa native flavanols.

Development and Characterization of a Pilot-Scale Model Cocoa Fermentation System Suitable for Studying the Impact of Fermentation on Putative Bioactive Compounds and Bioactivity of Cocoa

Cocoa is a concentrated source of dietary flavanols—putative bioactive compounds associated with health benefits. It is known that fermentation and roasting reduce levels of native flavonoids in cocoa, and it is generally thought that this loss translates to reduced bioactivity. However, the mechanisms of these losses are poorly understood, and little data exist to support this paradigm that flavonoid loss results in reduced health benefits. To further facilitate large-scale studies of the impact of fermentation on cocoa flavanols, a controlled laboratory fermentation model system was increased in scale to a large (pilot) scale system. Raw cocoa beans (15 kg) were fermented in 16 L of a simulated pulp media in duplicate for 168 h. The temperature of the fermentation was increased from 25–55 °C at a rate of 5 °C/24 h. As expected, total polyphenols and flavanol levels decreased as fermentation progressed (a loss of 18.3% total polyphenols and 14.4% loss of total flavanols during fermentation) but some increases were observed in the final timepoints (120–168 h). Fermentation substrates, metabolites and putative cocoa bioactive compounds were monitored and found to follow typical trends for on-farm cocoa heap fermentations. For example, sucrose levels in pulp declined from >40 mg/mL to undetectable at 96 h. This model system provides a controlled environment for further investigation into the potential for optimizing fermentation parameters to enhance the flavanol composition and the potential health benefits of the resultant cocoa beans.

Common gut microbial metabolites of dietary flavonoids exert potent protective activities in β-cells and skeletal muscle cells

Flavonoids are dietary compounds with potential anti-diabetes activities. Many flavonoids have poor bioavailability and thus low circulating concentrations. Unabsorbed flavonoids are metabolized by the gut microbiota to smaller metabolites, which are more bioavailable than their precursors. The activities of these metabolites may be partly responsible for associations between flavonoids and health. However, these activities remain poorly understood. We investigated bioactivities of flavonoid microbial metabolites [hippuric acid (HA), homovanillic acid (HVA), and 5-phenylvaleric acid (5PVA)] in primary skeletal muscle and β-cells compared to a native flavonoid [(-)-epicatechin, EC]. In muscle, EC was the most potent stimulator of glucose oxidation, while 5PVA and HA simulated glucose metabolism at 25 μM, and all compounds preserved mitochondrial function after insult. However, EC and the metabolites did not uncouple mitochonndrial respiration, with the exception of 5PVA at10 μM. In β-cells, all metabolites more potently enhanced glucose-stimulated insulin secretion (GSIS) compared to EC. Unlike EC, the metabolites appear to enhance GSIS without enhancing β-cell mitochondrial respiration or increasing expression of mitochondrial electron transport chain components, and with varying effects on β-cell insulin content. The present results demonstrate the activities of flavonoid microbial metabolites for preservation of β-cell function and glucose utilization. Additionally, our data suggest that metabolites and native compounds may act by distinct mechanisms, suggesting complementary and synergistic activities in vivo which warrant further investigation. This raises the intriguing prospect that bioavailability of native dietary flavonoids may not be as critical of a limiting factor to bioactivity as previously thought.

Characterization of new flavan-3-ol derivatives in fermented cocoa beans

Two series of compounds showing mass signals at m/z 605 and 893 (negative ionization mode) have been detected in fermented cocoa beans. This study objective is to identify these mass signals and characterize their structure in fermented cocoa samples. Our hypothesis is that these signals may correspond to ethyl-bridged flavan-3-ols resulting from flavan-3-ol condensation with acetaldehyde which is a microbial metabolite. Mass spectrometry was used to compare the retention times and mass fragmentation patterns between a model solution using epicatechin and procyanidin dimer B2, the major flavan-3-ols of cocoa, as precursors and extracts of fermented cocoa. Their identification was confirmed: four isomers of ethyl-linked epicatechin as well as several isomers of epicatechin-ethyl-procyanidin B2, in which B2 was mostly linked through its upper unit, were characterized in cocoa. This study demonstrates the presence of flavan-3-ol acetaldehyde condensation products in fermented cocoa beans and provides the first report of epicatechin-ethyl-procyanidin B2.

Impact of roasting on the flavan-3-ol composition, sensory-related chemistry, and in vitro pancreatic lipase inhibitory activity of cocoa beans

Roasting is an important cocoa processing step, but has been reported to reduce the polyphenol content in the beans. We investigated the impact of whole-bean roasting on the polyphenol content, aroma-related chemistry, and in vitro pancreatic lipase (PL) inhibitory activity of cocoa under a range of roasting conditions. Total phenolics, (-)-epicatechin, and proanthocyanidin (PAC) dimer - pentamer content was reduced by roasting. By contrast, roasting at 150 °C or greater increased the levels of catechin and PAC hexamers and heptamers. These compounds have greater PL inhibitory potency. Consistent with these changes in PAC composition and this previous data, we found that roasting at 170 °C time-dependently increased PL inhibitory activity. Cocoa aroma-related compounds increased with roasting above 100 °C, whereas deleterious sensory-related compounds formed at more severe temperatures. Our results indicate that cocoa roasting can be optimized to increase the content of larger PACs and anti-PL activity, while maintaining a favorable aroma profile.

From Cocoa to Chocolate: The Impact of Processing on In Vitro Antioxidant Activity and the Effects of Chocolate on Antioxidant Markers In Vivo

Chocolate is a product processed from cocoa rich in flavonoids, antioxidant compounds, and bioactive ingredients that have been associated with both its healthy and sensory properties. Chocolate production consists of a multistep process which, starting from cocoa beans, involves fermentation, drying, roasting, nib grinding and refining, conching, and tempering. During cocoa processing, the naturally occurring antioxidants (flavonoids) are lost, while others, such as Maillard reaction products, are formed. The final content of antioxidant compounds and the antioxidant activity of chocolate is a function of several variables, some related to the raw material and others related to processing and formulation. The aim of this mini-review is to revise the literature on the impact of full processing on the in vitro antioxidant activity of chocolate, providing a critical analysis of the implications of processing on the evaluation of the antioxidant effect of chocolate in in vivo studies in humans.

Flavanol concentrations do not predict dipeptidyl peptidase-IV inhibitory activities of four cocoas with different processing histories

Cocoa and its constituent bioactives (particularly flavanols) have reported anti-diabetic and anti-obesity activities. One potential mechanism of action is inhibition of dipeptidyl peptidase-IV (DPP4), the enzyme that inactivates incretin hormones such as glucagon-like peptide-1 and gastric inhibitory peptide. The objective of this study was to determine the DPP4 inhibitory activities of cocoas with different processing histories, and identify processing factors and bioactive compounds that predict DPP4 inhibition. IC₂₅ values (μg mL^-1) were 4.82 for Diprotin A (positive control), 2135 for fermented bean extract, 1585 for unfermented bean extract, 2871 for unfermented liquor extract, and 1076 for fermented liquor extract This suggests mild inhibitory activity. Surprisingly, protein binding activity, total polyphenol, total flavanol, individual flavanol and complex fermentation/roasting product levels were all positively correlated to IC₂₅ concentrations (greater levels correspond to less potent inhibition). For the representative samples studied, fermentation appeared to improve inhibition. This study suggests that cocoa may possess mild DPP4 inhibitory activity, and that processing steps such as fermentation may actually enhance activity. Furthermore, this activity and the variation between samples were not easily explainable by traditional putative bioactives in cocoa. The compounds driving this activity, and the associated mechanism(s) by which this inhibition occurs, remain to be elucidated.

Correlation between Antimicrobial, Antioxidant Activity, and Polyphenols of Alkalized/Nonalkalized Cocoa Powders

Many factors can influence antioxidative and antimicrobial characteristics of plant materials. The quality of cocoa as functional food ingredient is influenced through its processing. The main aim of this study was to test if there is difference in polyphenol content, antioxidant capacity, and antimicrobial activity between nonalkalized and alkalized cocoa powders. To estimate polyphenol and flavonoid content in cocoa samples the spectrophotometric microassays were used. Flavan-3ols were determined with reversed-phase high-performance liquid chromatography (RP-HPLC). Antimicrobial activity against 3 Gram positive bacteria, 4 Gram negative bacteria and 1 strain of yeast was determined using broth microdilution method. Total polyphenol content was 1.8 times lower in alkalized cocoa samples than in natural ones. Epicatechin/catechin ratio was changed due to the process of alkalization in favor of catechin (2.21 in natural and 1.45 in alkalized cocoa powders). Combined results of 3 antioxidative tests (DPPH, FRAP, ABTS) were used for calculation of RACI (Relative Antioxidant Capacity Index) and GAS (Global Antioxidant Score) values that were consistently higher in natural than in alkalized cocoa extracts. Obtained results have shown significant correlations between these values and phenolic content (0.929 ≤ r ≤ 0.957, P < 0.01). Antimicrobial activity varied from 5.0 to 25.0 mg/ml (MICs), while Candida albicans was the most sensitive tested microorganism. Cocoa powders subjected to alkalization had significantly reduced content of total and specific phenolic compounds and reduced antioxidant capacity (P < 0.05), but their antimicrobial activity was equal for Gram-positive bacteria or even significantly enhanced for Gram-negative bacteria.

High-molecular-weight cocoa procyanidins possess enhanced insulin-enhancing and insulin mimetic activities in human primary skeletal muscle cells compared to smaller procyanidins

Dysregulation of glucose metabolism is a primary hallmark of metabolic disease (i.e., diabetes, obesity, etc.). Complementary nonpharmaceutical strategies are needed to prevent and/or ameliorate dysregulation of glucose metabolism and prevent progression from normoglycemia to prediabetes and type 2 diabetes across the lifespan. Cocoa compounds, particularly the procyanidins, have shown promise for improving insulin sensitivity and blood glucose homeostasis. However, the molecular mechanisms by which cocoa procyanidins exert these functions remain poorly understood. Furthermore, cocoa procyanidins exhibit size diversity, and evidence suggests that procyanidin bioactivity and size may be related. Here, we show that a procyanidin-rich cocoa extract elicits an antidiabetic effect by stimulating glycogen synthesis and glucose uptake, independent of insulin. Cocoa procyanidins did not appear to act via stimulation of AMPK or CaMKII activities. Additionally, in the presence of insulin, glycogen synthesis and AKT phosphorylation were affected. These mechanisms of action are most pronounced in response to oligomeric and polymeric procyanidins. These results demonstrate (1) specific mechanisms by which cocoa procyanidins improve glucose utilization in skeletal muscle and (2) that larger procyanidins appear to possess enhanced activities. These mechanistic insights suggest specific strategies and biological contexts that may be exploited to maximize the antidiabetic benefits of cocoa procyanidins.