RESUMO
Queso Chihuahua, a semi-hard cheese manufactured from raw milk (RM) in northern Mexico, is being replaced by pasteurized milk (PM) versions because of food safety concerns and the desire for longer shelf life. In this study, the functional traits of authentic Mexican Queso Chihuahua made from RM or PM were characterized to identify sources of variation and to determine if pasteurization of the cheese milk resulted in changes to the functional properties. Two brands of RM cheese and 2 brands of PM cheese obtained in 3 seasons of the year from 4 manufacturers in Chihuahua, Mexico, were analyzed after 0, 4, 8, 12, and 16 wk of storage at 4°C. A color measurement spectrophotometer was used to collect color data before and after heating at 232°C for 5 min or 130°C for 75 min. Meltability was measured using the Schreiber Melt Test on samples heated to 232°C for 5 min. Sliceability (the force required to cut through a sample) was measured using a texture analyzer fitted with a wire cutter attachment. Proteolysis was tracked using sodium dodecyl sulfate-PAGE. Compared with PM cheeses, RM cheeses showed less browning upon heating, melted more at 232°C, and initially required a greater cutting force. With aging, cheeses increased in meltability, decreased in whiteness when measured before heating, and required less cutting force to slice. Seasonal variations in the cheesemilk had minimal or no effect on the functional properties. The differences in the functional properties can be attributed, in part, to the mixed microflora present in the RM cheeses compared with the more homogeneous microflora added during the manufacture of PM cheeses. The degree of proteolysis and subsequent integrity of the cheese matrix contribute to melt, slice, and color properties of the RM and PM cheeses. Understanding the functional properties of the authentic RM cheeses will help researchers and cheesemakers develop pasteurized versions that maintain the traditional traits desired in the cheeses.
Assuntos
Queijo , Queijo/análise , Queijo/normas , Cor , Armazenamento de Alimentos , Dureza , México , Proteínas do Leite/análise , Estações do Ano , Fatores de Tempo , Água/análiseRESUMO
This work was performed to identify the bacterial species present in 10 Chihuahua cheeses obtained from commercial producers in Mexico using 16S rRNA gene analysis. As expected, some of the agar media initially used for isolation were not very selective, supporting the growth of several unrelated bacterial species. Sequence analysis identified potential pathogens, including Escherichia coli and Staphylococcus aureus, in all raw milk samples and 2 pasteurized milk samples. Streptococcus thermophilus and Lactococcus lactis ssp. lactis were identified in 9 and 6 samples, respectively, and would serve as acidifying agents during cheese production. Lactobacilli were identified in all cheeses, with the most prevalent being Lactobacillus plantarum identified in 7 raw milk and 1 pasteurized milk cheeses. Leuconostoc mesenteroides and Streptococcus macedonicus were identified in 4 raw milk cheeses and both were present in all pasteurized milk samples, suggesting that they may play a role in the development of traditional Chihuahua cheese attributes.
Assuntos
Bactérias/genética , Queijo/microbiologia , Microbiologia de Alimentos , RNA Ribossômico 16S/genética , Animais , Bactérias/classificação , México , Leite/microbiologiaRESUMO
Hispanic-style cheeses are one of the fastest growing varieties in the United States, making up approximately 2% of the total cheese production in this country. Queso Fresco is one of most popular Hispanic-style cheeses. Protein extracts from several varieties of Mexican Queso Fresco and model Queso Fresco were analyzed for potential antihypertensive activity. Many Quesos Frescos obtained from Mexico are made from raw milk and therefore the native microflora is included in the cheese-making process. Model Queso Fresco samples were made from pasteurized milk and did not utilize starter cultures. Water-soluble protein extracts from 6 Mexican Quesos Frescos and 12 model cheeses were obtained and assayed for their ability to inhibit angiotensin-converting enzyme, implying potential as foods that can help to lower blood pressure. All model cheeses displayed antihypertensive activity, but mainly after 8 wk of aging when they were no longer consumable, whereas the Mexican samples did display some angiotensin-converting enzyme inhibitory action after minimal aging.
Assuntos
Inibidores da Enzima Conversora de Angiotensina/isolamento & purificação , Anti-Hipertensivos/isolamento & purificação , Queijo/análise , Alimento Funcional/análise , Proteínas do Leite/farmacologia , Animais , Manipulação de Alimentos , México , Fatores de Tempo , Estados UnidosRESUMO
Sensory profiles of fresh semihard Chihuahua cheese produced in the northern Mexican state of Chihuahua were developed to characterize the flavors and textures of this traditionally made Hispanic-style cheese. Multiple allotments of Chihuahua cheese, 9 brands made with raw milk (RM) and 5 brands made with pasteurized milk (PM), were obtained within 3 d of manufacture from 12 different cheese plants throughout Chihuahua, México. Cheeses were shipped overnight to Wyndmoor, Pennsylvania, and flavor analyses were conducted within 14 to 18 d after manufacture. Four brands (2 RM and 2 PM cheeses) were then selected and multiple allotments were shipped at 3 distinct seasons over a 1-yr period for evaluation of flavor and texture. Microbial analysis was conducted prior to testing to ensure product safety. Descriptive analyses of cheese flavors and textures were conducted with panelists trained to use a universal or product-specific Spectrum intensity scale, respectively. Sensory profiles of cheeses varied among the different manufacturers. The most prominent flavor attributes were salty, sour, diacetyl, cooked, whey, bitter, and milk-fat. The RM cheeses had more intense sour, bitter, and prickle scores than the PM cheeses. Many cheese texture attributes were similar, but RM cheeses were perceived as softer than PM cheeses. As the demand for Hispanic-style cheeses increases, defining and understanding the sensory attributes of traditionally made Mexican cheeses provides guidance to cheese manufacturers as new ways are explored to improve the production and shelf life of the cheeses.