28-7 |
Sensory, instrumental and compositional analysis of high-pressure treated, fresh renneted cheese |
S. SANDRA1, M. Stanford, and L. M. Goddik. (1) Food Science and Technology, Oregon State University, 100 Wiegand Hall, Corvallis, OR 97331-6602 Fresh cheese is gaining popularity in the USA due to the diverse population and its increasing demand for ethnic foods. Consumption of raw milk fresh cheese has been linked to several outbreaks. High hydrostatic pressure (HHP) treatment reduces microbial load, with insignificant effect on foods’ flavor, texture, and nutritional content. Research on fresh cheese and HHP in relation to safety and sensory is limited. The research objective was to investigate if HHP treated raw milk cheese (HP) or cheese made from HHP treated cheese milk (HPM) provide safer cheese with sensory characteristics similar to raw milk (control) fresh cheese. Cheese was made based on a modified Queso Fresco process. HHP treatment was employed at ambient temperature, 400 MPa for 20 min. Coliform, Aerobic plate, Yeast and Mold counts were done to determine microbial inactivation. Fat, moisture, and protein contents were determined by Mojonnier, Forced-draft oven, and Kjeldahl respectively. Microscopy was used to show fat-protein interactions. Texture was evaluated by descriptive panel and texture analyzer. At least duplicate analyses were done. Storage time of 1 and 8 days were studied. Control (pH 5.16(±0.12)), HP (pH 5.22(±0.04)), and HPM (pH 5.13(±0.08)) moisture contents were 46.3 %(±4.0), 45.4 %(±1.3), 55.7 %(±1.9) correspondingly after one day. The cheeses’ compositional and sensory attributes did not change significantly (p-value<0.05) during storage time studied. HPM cheese had significantly higher moistness, cohesiveness, wetness-oiliness residue and lower firmness than both HP and control. HPM and HP had lower microbial load than control. Fat-protein interactions of HP were similar to control. HPM had almost no fat-protein interactions. The results indicate that HHP of cheese can decrease microbial load, and provide sensory and compositional characteristics similar to that of control. HHP of cheese milk disrupts fat-protein interactions producing a soft cheese that is significantly different from control.
Session 28, Dairy Foods: Developments in microbiology and chemistry of cheese
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