Submitted to: Journal of Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2012
Publication Date: 10/1/2012
Citation: Paul, M., Nunez, A., Van Hekken, D.L., Renye Jr, J.A. 2012. PROTEIN & SENSORY ANALYSIS TO CHARACTERIZE MEXICAN CHIHUAHUA CHEESES. Journal of Food Science and Technology. DOI: 10.1007/s13197-012-0868-8.
Interpretive Summary: Queso Chihuahua is a raw milk cheese made in Mexico that is typically consumed within 1 month of manufacture. While the popularity of this and other types of Hispanic-style cheeses are increasing with the growing Hispanic population in the US, raw milk cheeses can not be sold in the US until they are aged for sixty days. This is because the native bacterial content of some raw milk used for making artisanal cheeses can include pathogen and food spoilage bacteria. This research addresses understanding the components within Queso Chihuahua that bestow the final product with its taste and textural properties. Specifically, this study explores the breakdown of milk proteins that may lead to the specific flavors found in Queso Chihuahua. This information will aid in the development of a pasteurized milk cheese for U.S. consumers that mimics the taste and texture properties of the raw milk Queso Chihuahua cheeses but with the safety of a pasteurized product.
Technical Abstract: It has been established that native microflora in raw milk cheeses, including Queso Chihuahua, a Mexican cheese variety, contributes to the development of unique flavors through degradation of milk proteins resulting in the release of free amino acids and short peptides that influence the taste and texture of these products. The extent and effects of proteolysis were studied in four different brands of Mexican Queso Chihuahua cheese made with raw milk. Each sample was analyzed for sensory characteristics as well as for moisture, protein, fat, lactose, and salt content. Sensory testing indicated that all four cheeses elicited flavors associated with young, basic cheeses, with slight bitter notes. Analysis of each cheese sample by SDS-PAGE and RP-HPLC revealed that two of four (X and Z) samples show little protein degradation over time while the proteins in the remaining two samples (W and Y) are degraded dramatically when allowed to age at 4 oC for 8 weeks. Using MALDI-TOF/TOF mass spectrometry to analyze the mixture of protein and peptide components contained in the water soluble portions of these cheeses revealed the presence of short, relatively hydrophobic peptides in quantities that correlated to the bitterness observed, i.e. the higher the number of hydrophobic peptides, the more bitter the cheese. Previous work on identification of the microflora in these cheeses showed the presence of a number of different bacterial species. All four samples showed the presence of enterococcal strains with the potential to produce enterocins. Two samples, W and Y, had the highest number of bacteria and displayed the greatest protein degradation over time, indicating that the elevated levels of proteolysis observed in these samples relative to the other two samples, X and Z, is most likely due to the increased numbers of contaminating bacteria.