Utilization of konjac glucomannan as a fat replacer in low-fat and skimmed Mozzarella cheese

Abstract

The production of reduced-fat foods has been a preoccupation of scientists and industry. Konjac glucomannan (KGM) is a natural polysaccharide with several desirable nutritional characteristics, and has the potential functional properties as a fat-replacer in dairy products. In our study, physicochemical, textural, pizza baking properties and structural characteristics of low-fat and skimmed Mozzarella cheese with KGM (LFKGM and SKKGM) were compared with those of full-fat, low-fat and skimmed Mozzarella cheese control (FFC, LFC and SKC) during 0, 7, 14, 21 and 28 d storage at 4°C. Generally, addition of KGM to Mozzarella cheese had no significant effects on protein and fat contents. The LFKGM and SKKGM exhibited higher whiteness, greenness and yellowness hues compared with those of LFC and SKC. While, LFKGM and SKKGM exhibited higher L*, lower a* and b* compared with LFC and SKC after heating, respectively. The L* decreased, a* remained stable and b* increased for all the cheese samples after heating compared with those of unheated samples during storage. The FFC, LFC and LFKGM had the same water activity (aw) and moisture values, but the aw of SKKGM was higher than SKC. The SKKGM and SKC had the same moisture content and both were higher than other cheese samples. The aw and moisture content of all the cheese samples remained stable during storage. Addition of KGM to low-fat Mozzarella cheese gave it a similar firmness to FFC blocks, which was lower than that of LFC during storage. There was no significant difference in stickiness of LFKGM and SKKGM with LFC and SKC during storage, respectively. The pizza bake test of LFKGM and SKKGM performed at D 7 and D 28 showed more adequate meltability and less scorching to the cheese shreds compared with LKC and SKC. Additionally, FFC and LFC showed long protein channels, while SKC, LFKGM and SKKGM showed densest protein matrix as observed by the confocal microscope during storage. Results indicated that KGM might be a good fat-replacer to develop reduced-fat Mozzarella cheese with desired characteristics.