UNIVERSITY PARK, Pa. — It is widely believed that when foods undergo processing, their health benefits are reduced. But that is not true for cocoa, according to a Penn State-led team of researchers, who conducted a new study using a mouse model.

To make chocolate, cocoa beans typically undergo fermentation and roasting, processes that can affect their polyphenol content — the compounds that provide health benefits, explained Joshua Lambert, professor of food science and research team leader. But results of this study indicate that processing does not reduce the health benefits of chocolate.

“In fact, just the opposite,” said Lambert, who is co-director of Penn State’s Center for Plant and Mushroom Foods for Health. “We found that some of the most processed samples seemed to have the largest positive impact on mice in this research. The aim of this study was to compare the effect of fermentation and roasting protocols on the ability of cocoa to mitigate obesity, gut barrier dysfunction and chronic inflammation in high-fat-fed, obese mice.”

In findings recently published in the Journal of Nutritional Biochemistry, the researchers reported that treatment of mice with dietary cocoa powder for eight weeks reduced the rate of body weight gain in both male and females by up to 57%, regardless of fermentation and roasting protocol.

The high-fat-fed mouse is a well-established, diet-induced model of obesity, noted Lambert, whose research group in the College of Agricultural Sciences has been assessing the health benefits of foods and beverages such as chocolate and green tea in mouse models for two decades. By waiting until mice are already obese before beginning cocoa treatment, researchers can test the protective effects of cocoa in a model that better simulates the current public health situation related to obesity and associated comorbidities.

This research — spearheaded by Daphne Weikart, a doctoral degree student in the Department of Food Science — is important, Lambert believes, because a significant proportion of the world’s population has preexisting obesity and non-alcohol-related fatty liver disease. “Given the high proportion of people in the United States and other parts of the world with obesity, there is a need to develop potentially effective dietary interventions,” he said.

Cocoa is subjected to extensive processing because it results in the development of desirable flavor and aroma compounds, prior to use as an ingredient, Lambert pointed out. “While these processes are essential for consumer acceptability of cocoa products, both fermentation and roasting have been shown to decrease total polyphenol concentration by up to 18%,” he said.

To test the effect of processing, groups of high fat-fed mice in the study were fed seven different dietary supplements of cocoa powder over eight weeks. Those supplements were formulated from beans that had been prepared differently, ranging from no fermentation and no roasting to extensive fermentation and roasting at high temperature — and various combinations.

Cocoa powders were incorporated into the mice’s diet in a concentration of 80 milligrams of cocoa powder to each gram of feed. For human comparison, Lambert explained, that is equivalent to the amount of cocoa powder in five cups of hot cocoa, at two tablespoons of cocoa powder per cup.

The researchers found that the treatment of mice with dietary cocoa powder reduced the rate of body weight gain in both males and females, regardless of fermentation and roasting protocol. “Processing reduced the polyphenolic content in the cocoa,” Lambert said. “But the composition of polyphenolic chemicals that remained shifted in such a way that there were more of what we suspect to be the most effective polyphenols.”

Gut permeability, which is an important contributor to development of fatty liver disease, was reduced by up to 79% by cocoa supplementation. Analysis of the mice’s intestinal microbiome showed that cocoa, regardless of fermentation and roasting protocol, reduced the ratio of Firmicutes to Bacteroidetes — an important measure of flora in the colon relating to obesity.

Based on this data, the researchers reported, there was strong protective efficacy from cocoa supplementation, especially for the more processed cocoa samples. Overall, they suggested, this study shows that anti-obesity and anti-inflammatory efficacy of cocoa is resilient to changes in polyphenol content and composition induced by fermentation or roasting.

The mechanisms by which cocoa imparts health benefits are not well understood, but previous studies in Lambert’s lab showed that some of the chemicals in cocoa powder can inhibit the enzymes that are responsible for digesting dietary fat and carbohydrate.

The result, he proposes, is that when mice get cocoa as part of their diet, these compounds in the cocoa powder reduce the digestion of dietary fat. When it can’t be absorbed, the fat passes through their digestive systems. A similar process may occur with cocoa in humans, he hypothesizes.

Contributing to the research at Penn State were Jasna Kovac, Lester Earl and Veronica Casida Career Development Professor of Food Safety; Darrell Cockburn, assistant professor of food science; Helene Hopfer, Rasmussen Career Development Professor in Food Science; Vijaya Indukuri, postdoctoral scholar in the Department of Food Science; and Kiana Coleman, master’s degree student in food science; and Kathryn Racine and Andrew Neilson, Department of Food, Bioprocessing, and Nutrition Sciences and the Plants for Human Health Institute, North Carolina State University.

This study was supported in part by the United States Department of Agriculture.