14A-23 |
Microstructure and textural characteristics of reduced fat Edam cheeses containing adjunct cultures during ripening |
W. TUNGJAROENCHAI, Dept. of Agricultural-Industry, King Mongkut's Institute of Technology, Ladkrabang, Bangkok, Thailand, C. H. White, Dept. of Food Science & Technology, Mississippi State Univ., 105 Herzer Bldg., Campus Mailstop 9805, Mississippi State, MS 39762-9805, and R. S. Chamul, Dept. of Kinesiology & Nutritional Science, California State Univ., Los Angeles, 5151 State University Dr., Physical Education 236, Los Angeles, CA 90032-4226. Texture analysis has been used to monitor quality of cheeses with different processing conditions or compositions by studying their microstructure as measured by electron microscopy. The objectives of this study were to investigate the textural characteristics and microstructures of reduced-fat Edam cheese containing mixtures of adjunct cultures during ripening. Full-fat control, reduced-fat control, and reduced-fat Edam cheeses containing adjunct cultures (Brevibacterium linens, Lactococcus lactis ssp. diacetylactis, Lactobacillus helveticus, and Lactobacillus reuteri) were produced. Scanning microscopy samples were prepared and examined on a Leico/Cambridge microscope. Transmission microscopy samples were examined on a JEOL transmission microscope. Texture evaluation of cheese samples was performed using an Instron 101 instrument with a two-cycle compression test with sample deformation at 50% of the sample original height. Mean fat and protein content of the full-fat cheese were 30.06% and 41.69 %, while the mean fat and protein content of reduced- fat cheeses were 20.85 % and 51.26%, respectively. The level of milkfat in cheese had a significant effect on the protein matrix as determined by SEM. Proteolysis during ripening led to hardening and reduced springiness and chewiness in all cheeses. Mixed adjunct cultures in reduced-fat cheese showed the same chewiness quality as the full-fat cheese. A decrease in cohesiveness was obtained as a result of added mixed adjunct cultures in reduced-fat cheese during ripening. Microstructures of full-fat cheese had uniformly distributed fat pools with sizes ranging from 27.67 to 29.42 square microns. Size of fat globules in reduced-fat cheese was in the range of 39.21 to 45.55 square microns; meanwhile a wider range of fat globule size (17.91 to 51.37 square microns) was found in the reduced-fat with mixed adjunct cultures. Cheese composition and microbial activity influenced the microstructure of cheeses. Microstructure of cheese was found to be a dynamic phenomenon during ripening.
Session 14A, Dairy Foods: General developments in dairy technology I
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