Browsing by Subject "Astringency"
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Item Comparing astringency and sourness of whey protein beverages acidified with four different acids(2015-03) Dornbusch, Abby M.Increasing interest in whey protein beverages stems from the wide range of nutritional benefits whey proteins have to offer. A useful characteristic of whey proteins is their solubility over a wide pH range, however in order to ensure clarity of a ready-to-drink whey protein beverage, it needs to be manufactured at a pH of approximately 3.4. At an acidic pH of 3.4, the beverages become astringent and can lead to consumer acceptability issues. The main objective of this research was to determine which, if any, of four different acids (hydrochloric, malic, phosphoric, tartaric) achieved the lowest perceived astringency rating when used to acidify a 4% (w/v) whey protein isolate (WPI) solution to pH 3.4. A secondary objective was to identify the buffer capacities of each acid in both a water solution and WPI solution, in efforts to detect a relationship between buffer capacity and perceived astringency. Sourness ratings for each sample were also gathered. A 4% (w/v) WPI solution acidified with hydrochloric acid generated the lowest perceived astringency and sourness ratings. Conversely, the malic acid WPI sample produced the highest perceived astringency rating. Additionally, hydrochloric and phosphoric acid samples buffered the least within the pH range of interest (3.4-7.0). This research indicates a potential relationship between the perceived astringency of an acidified-WPI solution and the buffer capacity of the acidulant used.Item Sensory aspects of astringency and changes of the oral environment in the mechanism of astringency.(2010-08) Lee, Catherine A.Astringency, a tactile sensation felt in the mouth after exposure to various foods, is not well understood. The underlying mechanism is not fully known, and it remains a challenging attribute to assess in sensory tests. Additionally, while most food astringency is caused by polyphenolic compounds, the cause of astringency in some other foods is not known. For the first part of my research, my objective was to improve the understanding of the mechanism of astringency by determining if it was related to a loss of saliva's ability to lubricate, the precipitation of specific classes of salivary proteins, or to the removal of oral lubricating films that coat the inside of the mouth. My results show that while astringency may be related to the latter, astringency is not related to a loss of salivary lubricity or the precipitation of any one class of salivary proteins. The second part of my research aimed to improve palate cleansing strategies for astringent foods. Palate cleansers are often used in an attempt to reduce build-up of astringency intensity that occurs over repeated exposures to astringent foods, but it is unknown how, or if, commonly used palate cleansers affect a person's sensitivity to astringency. Although I did not find that any of the cleansers were superior in their ability to limit the build-up of astringency intensity, it was clear that panelists were better able to discriminate among the astringency of various strength solutions when they used nothing or water to cleanse their palates. The aim of part III of my research was to determine the cause of astringency in acidic whey protein beverages. Although some believe that the whey proteins directly cause the astringency, there was reason to suspect that their high acid concentration was instead responsible. The results of my study found this to be true.