|Van Hekken, Diane|
Submitted to: Food Protection Trends
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/5/2005
Publication Date: 8/20/2005
Citation: Bricker, A.L., Van Hekken, D.L., Guerrero, V.M., Gardea, A.A. 2005. Microflora isolated from Mexican Mennonite-style cheeses. Food Protection Trends. 25(8):p.637-640. Interpretive Summary: Hispanic-style cheese is becoming more popular in the United States as the Hispanic population grows and Americans in general become more familiar with authentic Latin-style cuisine. Many of these cheeses found in the United States are based on Mexican cheeses traditionally made from raw, unpasteurized milk, which are not allowed in the United States due to the health risk if the cheese is eaten too soon after manufacture. Mennonnite-style cheese from Chihuahua, Mexico, often is made from raw milk. In this study we identified the groups of bacteria present in Mennonite-style cheese samples made from either raw or pasteurized milk. As expected, undesirable bacteria were isolated from cheeses made with raw milk, but not from those made from pasteurized milk. There were other differences between the two groups of cheese samples. Most interesting was a comparison between the two pasteurized milk cheeses in the amounts of three different groups of cheesemaking bacteria present in each. This study confirmed that there are differences between the bacteria present in raw and pasteurized milk cheeses of the same type. It also suggested that some of the bacterial groups isolated from these cheeses are unnecessary for the manufacture of Mennonite-style cheese. Thus, it should be possible to begin developing a method for manufacturing typical Mennonite-style cheese using pasteurized milk for a healthier, longer-lived product.
Technical Abstract: Microflora were isolated from 10 freshly manufactured Mexican Mennonite-style cheese samples and compared to assess the relative importance of various types of bacteria on the manufacture of the cheese. Eight of the commercially manufactured samples were made from raw milk, while two were made from pasteurized milk inoculated with mixed commercial starter cultures. Generally, coliforms, enterococci, and coagulase positive staphylococci were present in raw milk cheeses but not pasteurized milk cheeses. Levels of mesophilic and thermophilic lactococci did not vary widely between the two groups, being present at relatively high levels (106-108 colony forming units per gram) in all samples. Thermophilic lactobacilli were slightly less populous in pasteurized milk cheeses (1-1.5 log10 fewer bacteria), while levels of mesophilic lactobacilli and Leuconostoc spp., as well as non-Lactobacillus mesophiles, were significantly lower in a single pasteurized sample (4 -5 log10 reductions). This survey of the groups of bacteria present in Mennonite-style cheeses demonstrates the variety of microflora to be found even in a single type of cheese. The distinction between raw milk and pasteurized milk cheeses, as well as between the two pasteurized milk cheeses, demonstrates the potential for creating typical Mennonite-style cheese from pasteurized milk with a greatly simplified bacterial content.