Characterization of Queso Fresco cheeses manufactured in Mexico and the United States.

Queso Fresco is a fresh, high moisture, white, rennet-set cheese that is the most popular Hispanic-style cheese in the US and Mexico. Traditionally, Mexican Queso Fresco is made with raw milk although the use of pasteurized milk is slowly replacing this practice. In the US, the FDA mandates that cheeses, such as Queso Fresco, sold less than 60 d after manufacture must be made with pasteurized milk. Queso Fresco has not been studied extensively and it is not known if the pasteurized milk cheeses are different from the raw milk originals. In this study, the compositional (moisture, fat, protein, and salt) and physical properties (whiteness value, water activity, and pH) of Queso Fresco from 6 commercial cheese plants in Sonora, Mexico (4 using raw milk and 2 using pasteurized milk) were characterized and compared to 8 commercial US-made cheeses. In composition, raw milk cheeses were higher in moisture (58-60%), and lower in fat (20-24%) and protein (15-17%) than the pasteurized milk cheeses from Mexico and the US (47-52% moisture, 23-36% fat, and 18-24% protein); the US-made cheeses contained more salt than the Mexicanmade cheeses (1.2-1.9% and 0.7-1.2%, respectively). In physical properties, all cheeses were bright white (whiteness L* values of 92-93) whereas raw milk cheeses had higher water activities (0.980 to 0.998) than the pasteurized cheeses (clustered near 0.975). The pH values of Mexican-made cheeses ranged from 4.8 to 6.0 whereas the pH values of US-made cheeses were above 6. The differences in manufacturing techniques, the unique microflora presence in the raw milk, and the excessive acid production in some of the cheeses contributed to the differences noted in composition and physical properties of the Queso Frescos. Establishing the basic chemical and physical properties of Queso Fresco is the first step in understanding the unique quality traits of this cheese and identifies traits that need to be maintained in pasteurized versions. [ABSTRACT FROM AUTHOR]