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Impact of milk fat globule membrane materials on cheese made from reconstituted milk: Structure and volatile organic compounds.

H. Zheng




Impact of milk fat globule membrane materials on cheese made from reconstituted milk: Structure and volatile organic compounds.
H. Zheng*1,2, M. Arnold2, K. Kilcawley3, T. Harding4, M. Weststeyn2. 1Department of Food, Bioprocessing and Nutrition Sciences, Southeast Dairy Foods Research Center, North Carolina State University Raleigh, NC, 2Dairy Innovation Institute, Animal Science Department, College of Agriculture, Food and Environmental Sciences, California Polytechnic State University San Luis Obispo, CA, 3Teagasc Food Research Centre Moorepark Fermoy, Ireland, 4Department of Materials Engineering, College of Engineering, California Polytechnic State University San Luis Obispo, CA.

In this research, we aim to develop a technology for manufacturing high quality cheddar style cheese using fully reconstituted milk system made from dried milk components and water to mimic key structural and flavor attributes of cheese made from fresh milk (M). Cheese made from reconstituted milk are different than the cheese made from fresh milk in terms of textural characteristics and flavor profiles. By using microfiltration and spray drying, we manufactured a milk fat globule membrane (MFGM) enriched ingredient from buttermilk, the ingredient is named as buttermilk concentrate (BMC). BMC was used to emulsify butter fat droplet in the reconstituted milk system (RM-BMC) for mimicking the sizes, surface structure and composition of native milk fat globules found in the fresh cheese milk. Reconstituted milk (RM) made without BMC is the control. Laser diffraction, confocal microscopy, electron microscopy and electrophoresis studies confirmed that the oil droplets in RM-BMC system have similar characteristics in comparison with native milk fat globules. However, the xanthine oxidase (a MFGM protein) load on the surface of oil droplet is 50% lower in RM-BMC (P < 0.05). After 5-mo ripening, the microstructure of RM-BMC-cheese can mimic fresh milk cheese (M-cheese) in terms of protein gel network and fat droplet distribution. SPME-GC-MS technique was used for analyzing volatile compounds in cheeses after different ripening period (fresh, 1-, 3-, 5-mo), in total we identified 38 volatile compounds (VOCs) consisting of ketones (9), aldehydes (7), benzenes (5) acids (4), terpenes (4), sulfurs (3), alcohols (2), lactone (1) and furan (1). Principal component analysis (PCA) of VOC composition ratios showed encouraging results that, after 5-mo ripening, RM-BMC-cheese showed similarity to M-cheese in terms of VOC profile because PC2 (16.6%) groups these 2 type samples together and discriminates the control (RM-cheese) apart. Moreover, at the same ripening point, the flavor profile of M-cheese is very different than the control because they are well separated by both PC1 (49.3%) and PC2 (16.6%).

Keywords: cheese, milk fat globule membrane, buttermilk.