| Abstract: |
6. SUMMARY AND CONCLUSSION PART 1EFFECT OF SOME NON STARTER LACTIC ACID BACTERIAL STRAINS ON THE QUALITY AND RIPENING CHANGES OF WHITE SOFT CHEESESoft cheese was mad from pasteurized mixed puffalos and cows milk (1:1) inoculated with 1% of either single non starter lactic acid bacterial cultures consisting of lactobacillus casei, Pediococcus damnosus strain DSM 20331, or Micrococcus luteus strain ATCC 9341 or treated with mixed non starter lactic acid bacteria at the rate (1:1:1). Cheese made with normal starter of Lactococcus lactis subsp lactis was taken as a control. The gross chemical composion, casein breakdown, fat hydrolysis and sensory evealuation of both fresh and after 2, 4, 6 and 8 wekks were investigated.Results showed that addition of nonstarter lactic acid bacterial cultures to cheese milk had no marked effect on the moisture, salt and fat contents of all treated cheeses when fresh and during cheese ripening, while cheese made with non starter lactic acid bacterial cultures had slightly higher acidity than the control cheese. Soft cheeses made with added non starter lactic acid bacterial cultures ripened faster than control cheese. The soluble nitrogenous compounds increased at a greater rate in cheese treated with added mixed non starter lactic acid bacterial cultures (1:1:1). Evalution of free fatty acids during ripening was also investigated and compared with that obtained for control cheese. Both control and experimental soft cheeses underwent slight lipolysis during ripening, resulting in the production of mostly short, medium and long chain fatty acids during ripening with higher concentrations of total free fatty acids than the control cheese. The organoleptic properties of cheese made with added mixed non starter lactic acid bacterial cultures at a proportion of (1:1:1) showed good organoleptic properties as compared with the control cheese.PART 2ACCELERATION OF WHITE SOFT CHEESE RIPENING AS AFFECTED BY NSLAB CULTURES AND P. ROQUEFORTI HYDROLYSED MILKThe effect of mixed strains of NSLAB, namely Lactobacillus casei Pediococcus damnosus strain DSM 20331, and Micrococcus luteus strain ATCC 9341 (1:1:1) as well as P. roqueforti hydrolsed milk on the acceleration of both proteolysis and lipolysis processes in white soft cheese was investigated. The obtained results indicated that soft cheeses containing mixed strains of NSLAB, (1:1:1) alone or with NSLAB + different levels of P. roqueforti hydrolsed milk at a rate 1, 2, or 3% had no significant effect on the gross chemical composition of soft cheese when fresh or during ripening. The obtained results showed also the addition of mixed strains of Lactobacillus casei Pediococcus damnosus strain DSM 20331, and Micrococcus luteus strain ATCC 9341 (1:1:1) cultures together with different level of P. roqueforti hydrolsed milk to cheese milk accelerated the formation of the soluble nitrogenous compounds and the concentration of these compounds were remarkably higher than the control cheese. The concentration of total volatile fatty acid (TVFA) and total non volatile fatty acids (TNVFA) were also higher in treated cheese than the control cheese. Moreover, cheese containing both NSLAB + 2% P. roqueforti hydrolsed milk had the best organoleptic properties compared with the control cheese.In conclusion, white soft cheese of better flavour as well as good body & texture characteristics could be manufactured using mixed strains of NSLAB Lactobacillus casei Pediococcus damnosus strain DSM 20331, and Micrococcus luteus strain ATCC 9341 (1:1:1). Improving the development of cheese flavour and acceleration of proteolysis and lipolysis process could by achieved by the addition of mixed strains of NSLAB Lactobacillus casei Pediococcus damnosus strain DSM 20331, and Micrococcus luteus strain ATCC 9341 (1:1:1) NSLAB coupled with 2% P. roqueforti hydrolysed milk to cheese milk. .
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