抄録
Cheddar type cheese was manufactured from milk using a commercial direct vat mesophilic starter culture. Varying amount of lyophilized crude extra cellular enzymes from Brevibacterium linens was mixed with salt and incorporated into cheese after milling to accelerate ripening process. Sensory and physico-chemical evaluation were carried out on control and experimental cheese over 16 wk at 2 wk interval. No off flavour, no bitterness and no significant differences on sensory parameters between experimental and control cheese was observed. Changes in moisture loss, pH and hardness in the experimental cheese did not differ significantly from the control. Cheeses with higher amount of enzymes contained higher levels of Non Protein Nitrogen and Non Casein Nitrogen than control. Increase in Amino nitrogen was higher in experimental cheeses than control. None of the cheeses showed complete degradation of αs1-casein at the end of 16 wk ripening. Hydrolysis rate of αs1-casein was more than β-casein during ripening. As a result of degradation one major peptide formation started after 2 wk and its degradation took place after 6 wk onward. This study revealed that crude extra cellular enzymes from B. linens are not effective in accelerating the ripening of Cheddar type cheeses as the enzymes are active in alkaline or neutral pH and may not be stable at pH 5.20-5.03 which is the normal pH at the initial stage of ripening.
