The Influence of Dietary Flavanol Mean Degrees of Polymerization on Sensory Preference Trends and the Metabolic Syndrome

• Main Author: Griffin, Laura E.
• Other Authors: Food Science and Technology
• Format: Others
• Published: Virginia Tech 2018
• Subjects: obesity; inflammation; cytokines; BMI; PROP sensitivity; bitterness; astringency
• Online Access: http://hdl.handle.net/10919/86238

According to the Centers for Disease Control, roughly 9.4% of the US population is diabetic, and at least 35% of the US population has metabolic syndrome. These diseases are associated with increased mortality risk, reduced quality of life, and altered taste perception of foods. With increased occurrence of these metabolic diseases, there is a greater need for research oriented towards using lifestyle modifications to combat illness. A relationship between flavanol consumption, health benefits, and taste perception has been well documented. Dietary flavanols are secondary plant metabolites that exist naturally in a wide array of polymerization states. The mechanisms behind the protective effects of flavanols are not entirely understood, particularly when considering how the mean degrees of polymerization (mDP), or average compound size, impacts the health benefits. Moreover, it is known that flavanol mDP influences the sensory attributes of flavanol-rich foods including bitterness and astringency. It is known that obesity and sensitivity to bitterness both influence perception of certain taste attributes such as sweetness and bitterness. The influence of these bitter and astringent sensations determined by flavanol mDP on consumer preferences for flavanol-rich products remains unknown. These influences on preference pose potential barriers to consumption, resulting in the loss of health benefits. The objectives of the research detailed here were i) to determine the effect of dietary consumption of small to medium-sized flavanols on markers of metabolic syndrome that were brought on by diet-induced obesity, ii) to determine how flavanol mDP influences the consumer perception and liking of flavanol-rich, wine-like products based on differences in consumer phenotype, and iii) to explore the potential to manipulate mDP of wine using traditional winemaking techniques. By way of an in vivo mouse model, it was observed that regardless of mDP, flavanols delivered at low dose, as part of a high-fat diet, reduced adipose-derived inflammatory cytokine production but did not prevent associated weight and fat gain. This suggests that small to medium sized flavanols may, at low dose, delay the onset of the pro-inflammatory state, which could ultimately protect against metabolic derangements associated with obesity and diabetes. Regarding the consumer acceptance of wine-like products made from flavanols of different mDP, and therefore different in bitterness and astringency intensity, it was observed in a consumer panel (n = 102) that when segmenting the panelists by body fat % and BMI classification, increased adiposity was associated with decreased ability to differentiate wine samples made with flavanols of different mDP. Moreover, differences in liking and ability to differentiate bitterness and astringency intensities were not as pronounced when segmenting the panelists based on bitterness sensitivity. This suggests that obesity may impact preference for flavanol-rich foods more so than sensitivity to flavor attributes associated with these products. Finally, in an exploratory effort to manipulate mDP of red and rosé wines using traditional winemaking techniques, no differences in mDP were observed in young wines, but significant differences in flavanol concentration were detected. It is hypothesized that aging of these wines could lead to greater differences in mDP, especially for those that had a high flavanol concentration at baseline. Future work will continue to build off these studies so that flavanol-rich products such as red wine can be optimized for health benefits and consumer acceptability of dietary polyphenols. === Ph. D. === According to the Centers for Disease Control, roughly 9.4% of the US population is diabetic, and at least 35% of the US population has metabolic syndrome. These diseases are associated with increased mortality risk, reduced quality of life, and altered taste perception for certain food types. With increased occurrence of these metabolic diseases, there is a greater need for research oriented towards using lifestyle modifications to combat illness. Dietary flavanols, which are potent antioxidants derived from plants, are being explored for their ability to mitigate chronic disease. They exist naturally in a wide variety of sizes and structures depending on plant of origin, growing conditions, and food processing conditions. It is believed that the size of these compounds impacts their health effects and influences their taste profile; smaller compounds are more bitter while larger compounds are more astringent. The purpose of this research was to determine the effect of flavanol supplementation on markers of the metabolic syndrome and how differences in taste due to differences in flavanol size influence consumer liking and perception of winelike products. It was determined in this study that dietary flavanols, delivered at low dose in the context of a high-fat diet can slightly improve fasting blood glucose levels and prevent inflammation. When examining consumer preferences for wines made from dietary flavanols that are distinctly different in terms of bitterness and astringency, it was determined that overall, consumers liked wines that were less intense in terms of bitterness and astringency. However, when examining consumers classified as having a high body fat percentage or high BMI, their ability to differentiate the wines was decreased compared to lean counterparts. These findings suggest that dietary flavanol supplementation at a physiologically relevant dose may improve symptoms of diabetes and metabolic syndrome. Future work confirming these observations in humans is warranted, as are studies devoted to better understanding of the taste preferences of the obese population. This will allow for optimization of flavanol-rich foods that maximize health benefit while also being palatable to consumers.