Document Type : Complete scientific research article
Authors
1
PhD graduate, Department of Food Process Engineering, Faculty of Food Science & Technology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
2
Professor, Department of Food Process Engineering, Faculty of Food Science & Technology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan
3
Professor, Department of Food Process Engineering, Faculty of Food Science & Technology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan Sciences & Natural Resources Gorgan, 49138-15739, Iran Tel/Fax: +98 17 32 42 30 80 Site: http://ziaiifar.profcms.gau.ac.ir/
4
Associate Professor, Department of Biosystems Engineering, Ferdowsi University of Mashhad, Iran Ferdowsi University of Mashhad Mashhad, Iran
Abstract
Background and objectives: Mozzarella is a soft cheese turns to a fibrous and elastic texture during a thermomechanical processes. Changing various functions including temperature, stretching time and screw speed, along with the storage conditions, could impress on textural and functional properties. These properties are more critical in low-fat mozzarella due to the fat content. Therefore, compensation this defect is the most important steps in low-fat mozzarella cheese producing. 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 was produced by pre-acidification and using fat-imitating compounds. Keeping constant the water temperature and screw speed in thermomechanical section, the effect of stretching time in hot water (2 and 8 minutes), storage temperature, citric acid, whey protein concentrate and sodium Caseinate on moisture, fat content, hardness, adhesiveness, springiness, cohesiveness, gumminess, chewiness, meltability and free oil formation were investigated after a week storage at 4° and -18°C. Moisture based on oven method and fat were determined by Gerber methods. Texture characteristics such as hardness, stickiness, cohesiveness, springiness, gum state, chewability were analyzed by a texture analysis, and functional characteristics including meltability and free oil formation were measured by standard experiments. One high and low fat sample of all products without any additional changing was considered as control samples. All treatments were analyzed by general linear model and univariate as a completely randomized Factorial design through IBM SPSS Statistics. 26 in 5% confidence level.
Results: It was found that, the more increased fat, the more loss of fat was observed in hot water in thermo-mechanical section. The moisture content of low-fat mozzarella significantly increased by whey protein concentrates, and then meltability also was improved in the same samples. Changing the stretching time from 2 to 8 minutes, hardness, springiness, gumminess, cohesiveness and chewability were increased. However, the Adhesiveness decreased while free oil became unchanged (P<0.05). Sodium Caseinate caused a reduction in hardness and Adhesiveness. At the same time, storage in -18°C caused a decrease in moisture content, as well as increase 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 process and formulation changes. Due to the reduction of the thermos-mechanical intensity, all textural properties except free-oil were improved. Addition of whey protein concentrate improved Meltability and sodium Caseinate produced softer cheese. However, except for increasing the formation of free oil and hardness, freezing did not have much effect on other characteristics. In general, it could be possible to produce low fat Mozzarella with more textural and functional characteristics by optimal changing in thermos-mechanical properties.
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