title: Utilization of konjac glucomannan as a fat replacer in low-fat and skimmed yogurt.
abstract: Konjac glucomannan (KGM) has been reported to be beneficial to human health, as well as having potential functional properties as a fat replacer in dairy products. In this study, 0.5% KGM solution was added to prepare low-fat (LFKGM) and skimmed (SKKGM) yogurts, and their physicochemical properties were compared with those of full-fat yogurt control (FFC), low-fat yogurt control (LFC), and skimmed yogurt control (SKC). Properties and composition were determined and the microscopic structures of all yogurts were observed during storage at 4°C for 21d. Generally, addition of KGM to yogurts had no significant effect on composition, pH, and titratable acidity at each storage day. The LFKGM and SKKGM had higher whiteness, greenness, and yellowness hues compared with those of the LFC and SKC. The proteolysis of LFKGM and SKKGM was similar to that of FFC, whereas it was lower than in LFC and SKC after 14d of storage. Addition of KGM had no positive effects on the water-holding capacity, but led to a decrease in syneresis and spontaneous whey separation in LFKGM and SKKGM compared with those of LFC and SKC. The spontaneous whey separation of LFKGM was similar to that of FFC. Presence of KGM in skimmed yogurt affected textural characteristics, while having little effect on texture of low-fat yogurt. Additionally, LFKGM and SKKGM showed stronger and more stable gel structures than those of FFC, LFC, and SKC. Overall, no substantial changes were found in the characteristics for each yogurt during storage, except for pH and gel structures. Results indicated that KGM may be a good fat replacer to develop reduced-fat yogurts with desired characteristics.
authors.affiliation: Food and Nutritional Sciences, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, Pokfulam 0000.
authors.forename: Shuhong
authors.initials: S
authors.lastname: Dai
authors.affiliation: Food and Nutritional Sciences, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, Pokfulam 0000; Department of Food Science and Technology, Shanghai Jiao Tong University, Shanghai, 200240, PR China.
authors.forename: Harold
authors.initials: H
authors.lastname: Corke
authors.affiliation: Food and Nutritional Sciences, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, Pokfulam 0000. Electronic address: npshah@hku.hk.
authors.forename: Nagendra P
authors.initials: NP
authors.lastname: Shah
mesh_terms: D000818:Animals; D018752:Diet, Fat-Restricted; D006801:Humans; D000067816:Whey Proteins; D015014:Yogurt
chemical_list: D000067816:Whey Proteins
keywords: konjac glucomannan; physiochemical property; structure; texture; yogurt