Research On The Screening Of Adjunct Culture Of Cheddar Cheese And Application In Accelerating Of Aging

In recent years, the cheese consumption increased rapidly in in China, and Cheddarcheese, especially aged Cheddar cheese, is one of the most popular cheeses in China for itsunique nutty flavor. Due to the long ripening period and high cost, the acceleration of theageing of Cheddar cheese is essential for the Dairy Industry. The application of adjunctculture in the production of Cheddar cheese will improve the quality of cheese, accelerate theripening of cheese and lower the costs. In addition, studies showed that consumers fromdifferent countries have different preference on the flavor of cheddar cheese, and there hasbeen no report on the Chinese consumer preference for the Cheddar cheese yet. Therefore, thepresent study investigated the Chinese consumer preference to Cheddar cheese, screened theadjunct culture with multiple indexes and explored the application of screened adjunct culturein Cheddar cheese.The current commercially imported cheddar cheese was mainly aged Cheddar cheese andfrom different countries. As the complexity of cheese manufacturing and ripening, manyfactors affected cheese flavor, including the source of the milk, starter culture, the cheeseprocessing, and variation in the flavor characteristics may exist among the cheese products inChina. Therefore revealing the flavor characteristics of the commercial Cheddar cheese andthe consumers preferences in China will help the development and production of Cheddarcheese suitable for the Chinese consumers. In the present study aged Cheddar cheeseimported from5countries were analyzed for volatiles and sensory characteristics. The resultsshowed there were regional differences in volatile profiles of the commercial Cheddar cheesefrom various countries, and the main difference was from the acid compounds. Chineseconsumers had distinct preferences for Cheddar cheese with nutty and milky characteristics inboth aroma and taste. However, Cheddar cheese with high intensity of sulfur flavor and bitterwas ranked low. Therefore, Cheddar cheese with nutty and milky characteristics and lowintensity of sulfur and bitter would be desirable for the Chinese consumers.According to the Chinese consumers preference for nutty, screening indexes were chosenfor selection of adjunct culture for nutty Cheddar cheese. Through the analysis of themetabolic pathways of nutty flavor compounds, methionine, leucine and phenylalanine wereselected as important amino acids of the current study. The potential adjunct culture wasscreened with a multi-step method by considering the growth of strains in cheese ripeningenvironment, acidifying abilities, autolysis degrees, proteolytic activities, aminotransferaseand glutamate dehydrogenase activities and three strains, CCFM237, CCFM410andCCFM412, with different characteristics were explored further for application as adjunctculture. Three strains all had a low ability of produce acids. Moreover, CCFM237had highautolysis, moderate total peptidase and GDH activities and had transformation activity on Phe;CCFM410had moderate autolysis and peptidase, high level of GDH and had transformationactivity on Phe, Leu and Met; CCFM412had high autolysis, total peptidase, GDH and hadtransformation activity on Phe, Leu. Considering these indexes, strain CCFM410was themost potential to used as adjunct culture of Cheddar cheese. The impact of selected strain CCFM410on Cheddar cheese was evaluated with a rapidripening model by determining the protein hydrolysis with WSN,5%PTA-SN,12%TCA-SNand free amino acids, volatile compounds and sensory of Cheddar cheese. The results showedthat the content of WSN and5%PTA-SN was significantly higher in experimental groupafter two weeks than the control group. It suggested that the addition of adjunct cultureaccelerated the process of formation of polypeptide and the generation of free amino acids,especially phenylalanine, leucine, glutamic acid, valine. The content of volatile compoundslike2,3-butanediol, benzaldehyde,3-methyl butanal,2-nonanone, isovaleraldehyde, nonanol,linalyl acetate were significantly higher in experimental group and the principal componentanalysis of sensory results showed that for the experimental cheese its corresponding agedCheddar cheese flavor characteristics was more pronounced than the control group after fourweeks of ripening, which indicated that CCFM410had an impact on cheese flavor, which canenhance the formation of aged cheese flavor.Strains CCFM237, CCFM410and CCFM412were used to produce Cheddar cheeseand ripened at8℃, humidity of85%for5months, and the impact of the three strains oncheese was investigated. The results showed that three strains accelerated the hydrolysis ofprotein and accelerated the ripening of cheese. Strains CCFM410and CCFM412affected theflavor of Cheddar cheese significantly with accelerating the step of transformation of Pheand Leu and enhanced the mutty flavor, however, they enhanced the sour flavor of cheese.Strain CCFM237with the same level of total peptidase with CCFM410had no significanteffect on cheese flavor, which showed aminotransferase can enhance the formation of cheeseflavor. Menwhile, the analysis result of screening indexes and cheese character showed thathigher proteolytic activity, more bitter and GDH would promote the formation of nutty.The results of the research showed that the established screening adjunct culture modelcould improve the formation of cheddar cheese nutty effectively. The aminotransferaseworked on leucine, phenylalanine and GDH promoted the formation of the nutty.Comprehensive considering acidifying abilities, autolysis degrees, proteolytic activities,aminotransferase and glutamate dehydrogenase activities can effectively improve cheeseflavor and speed up the maturation of cheese.