| Enzyme Modified Cheese Flavor(EMCF) as a concentrated natural cheese seasoning is more and more widely used in food processing due to its high flavor intensity, stable quality,and low production cost. While our country mainly depend on importing EMCF, so it has great significance to research on producing high quality EMCF by ourself. This study combined fermentation method with a two-step enzymolysis method to prepare EMCF, the influences of fermentation condition on acid and aroma production were analysed; After optimized proteolysis parameters, enzymatic influences of a single lipase and mixed lipase were compared,and then the lipolysis conditions were further studied. Aimed to improving the quality of EMCF and provide a technical base for the industrial production of EMCF; finally, the head volatile selecting, baking application and storage stability tests were performed. The main conclusions are as follows:(1) Whole milk powder as raw material, flavor producing lactic acid bacteria was selected as starter to prepare cheese slurry, acid-producing and aroma-producing ability of the starter were determined during static and shake flask fermentation, the results showed that aroma production under shake flask fermentation was about 3 times higher than in static fermentation,but the acid content was not significantly different, so shake flask fermentation method was chosed to prepare cheese slurry, what is more, fermentation conditions was optimized as follows:substrate concentration 25%(w/w), temperature 37 ℃, shaking speed 150 r/min, time 20 h, the diacetyl content of fermentation product was 42.28 mg/L, titratable acidity was 124 °T, which were significantly higher than that of the cheese on market.(2) The two-step enzymolysis method was used to hydrolyzed the protein and fat of the substrate. Though the single factor experiments and orthogonal experiments, which take pH4.6-WSN, 12%TCA-SN and taste score as index, determined that the ratio of protamex to flavourzyme was 1:2(w/w), and the best proteolysis conditions are as follows: the amount of protease 0.100%(w/w), temperature 45 ℃, time 8 h. Through FFA(%) and flavor score determination, the hydrolysis effect of single lipase was compared with that of compound lipase.The results showed that the hydrolysis effect of the compound enzyme was better than that of the single lipase, palatase 20000 L and lipase MER were selected for enzymatic reaction, the bestlipolysis conditions are as follows: palatase 20000 L 0.100%(w/w), lipase MER 0.150%(w/w),temperature 40 ℃, time 11 h.(3) Acids, ketones and esters were the main volatile components of homemade and commercial EMCF, but the acids and ketones content of homemade EMCF were 7.24% higher and 2.57% higher than commercial EMCF respectively, while the esters content and lactones content of homemade EMCF were lower than commercial EMCF, the data were 4.69% and2.42% according to this study. The free amino acids content in commercial EMCF was about double compared to homemade EMCF, but the bitter amino acids was 5.71% higher than homemade EMCF.(4) Suitable head volatile which named B1 was selected to cover up the difference of each batch EMCF flavor, and the ratio of B1 to EMCF was determined as 2.5:97.5(w/w). Through baking application and sensory evaluation after adding 2.0%(w/w) homemade EMCF, the biscuits had a thick cheese flavor without any bad aftertaste which also has long lasting time.Through the storage stability tests, the product kept well when it stored at 25 ℃, dark and sealed condition, the shelf life was over 6 months. |
PDF Full Text Request