Effect Of Liposome-encapsulated Neutral Proteinase On Cheddar Cheese Ripening

Cheddar cheese is very famous and popular in the world. However, the maturation period is quite long. And it will introduce extra costs to the production of cheese. So it's very necessary and essential to find a practical technology for accelerating Cheddar cheese ripening without any defect. Proteolysis play an essential role in cheese ripening. So it was applied to add liposome-encapsulated neutral proteinase(LENP) on Cheddar cheese in the experiments.The purpose of this research is to 1) study on the making of the liposome-encapsulated neutral proteinase for cheese making; 2)estimate the effects of LENP on pH, soluble N, texture, sensory evaluation and cheese yield during cheese ripening.The results of the experiments are as follows:1. Neutralproteinase was encapsulated in dehydration-rehydratin liposomes which were sonicated for 20min, 30min, 40min and 50min. The result showed that the treatment of 40min could get a satisfied result with an average diameter, regular shape. And neutral proteinase was encapsulated successfully.2. pH4.6 soluble N and 12%TCA soluble N were analyzed during cheese ripening. The results showed that degradation ofα- Casein andβ- Casien were enhanced and amounts of N soluble at pH4.6, in 12%TCA were significantly grown when LENP were added by 0.05%～1.0%; However it was not significantly influenced when the LENP were added by 0.001%～0.01%. The Urea-SDS-PAGE showed that degradation ofα-CN andβ-CN was enhanced when LENP were added by 0.1% after 60 day aging.3. The shear force and TPA parameters were studied during aging. The results showed 1) 0.001%～0.05% LENP had no significant effect on texture, but could improve the texture to some extent; 2) cheese texture was soften because of the more extensive proteolysis when LENP was added by 0.1%～1%. 4. Sensory value was effected by 0.1%～1.0% addition of LENP, which caused bitterness and texture soften; but not by 0.001%～0.05%.5. Degradation of casein was enhanced when LENP was added by 0.05% after 2 months. And the amounts of N soluble at pH4.6 and in 12%TCA were 22.9% and 10.46%. The values of hardness, springiness, cohesiveness were 194.8g, 0.879 and 0.53, which were similar to products in the market. And the ripening time was greatly improved to 2 months.