| Abstrakt: |
Background and objectives: Mozzarella is a soft cheese that turns to a fibrous and elastic texture during thermo-mechanical processes. Changing various functions, including temperature, stretching time and screw speed, along with the storage condition, could impact on textural and functional properties. These properties are more critical in low-fat mozzarella due to the fat content. Therefore, the compensating of this defect is one of the most important objects in low-fat mozzarella cheese production. According to studies, in addition to the possibility of adding fat-imitating compounds, changing the cooking and stretching conditions has a great impact on improving these characteristics. Materials and methods: Low-fat mozzarella cheese with 6% fat were produced by pre-acidification and using fat-imitating compounds. Keeping constant the water temperature and screw speed in the thermo mechanical section, the effect of stretching time in hot water (2 and 8 minutes), storage temperature, addition of citric acid, whey protein concentrate and sodium caseinate on moisture, fat content, hardness, adhesiveness, springiness, cohesiveness, gumminess, chewiness, melt ability and free oil formation were investigated after a week of storage at 4° and -18°C. Moisture based on the oven method and fat were determined by Gerber methods. Texture characteristics such as hardness, stickiness, cohesiveness, springiness, gum state, and chewability were analyzed by a texture analysis, and functional characteristics were measured by standard experiments. One of samples with high-fat or low-fat without any additives was considered as a control sample. All treatments were analyzed by a general linear model and univariate as a completely randomized factorial design through IBM SPSS Statistics. 26 at a 5% confidence level. Results: by increasing the fat content, the fat loss was increased in hot water in the thermomechanical section. The moisture content of low-fat mozzarella was significantly increased by addition of whey protein concentrates, and melt ability was also improved in the same samples. By changing the stretching time from 2 to 8 minutes, hardness, springiness, gumminess, cohesiveness and chew ability were increased. However, the adhesiveness decreased while free oil remained unchanged (P<0.05). Addition of sodium caseinate reduced the hardness and adhesiveness. At the same time, storage at frozen condition caused a reduction in moisture content, an increasing in hardness, and the accumulation of free oil due to structural damage in the cheese. Conclusion: All textural and functional characteristics were significantly affected by thermo-mechanical processes and formulation changes. Due to the reduction in thermo-mechanical intensity, all textural properties except free-oil were improved. The addition of whey protein concentrates improved melt ability, and sodium caseinate produced softer cheese. However, except of increasing the formation of free oil and hardness, freezing did not effect on other characteristics. In general, it could be possible to produce low-fat mozzarella with more textural and functional characteristics by optimizing changes in thermo-mechanical properties. [ABSTRACT FROM AUTHOR] |
