Accelerated Ripening of Ewes’ Milk Manchego Cheese: The Effect of Neutral Proteinases

The effect of two commercial preparations of neutral proteinase from Bacillus subtilis (Neutrase L and Novozym 257) on chemical, rheological, and sensory characteristics of Manchego cheese made from pasteurized ewes' milk and ripened for 90 d at 12 or 16'C was investigated. Levels of proteinase added to milk were in the range .001 to .004 Anson UnitsL of milk. Degradation of %leasein was not influenced by proteinase level; however, residual pcasein was lower in cheese made with .004 Anson units of proteinaseL Formation of pH 4.6-soluble N in cheese was more influenced by Neutrase L or Novozym proteinase addition than formation of TCA-soluble N or phosphotungstic acidsoluble N. Cheese made with Neutrase L proteinase was more crumbly and less elastic than control cheese, showing lower fracturability and hardness values. Frequency of bitter flavor was not significantly higher for cheese made with Neutrase L or Novozym proteinase than for control cheese. Flavor preference was not influenced by Neutrase L proteinase, but it was slightly impaired by Novozym proteinase. Flavor intensity was more enhanced by Neutrase L proteinase than by Novozym proteinase. Addition of .004 Anson units/L of Neutrase L proteinase would reduce ripening time by 15 d, an increase of 4'C in ripening temperature by 40 d, according io regression equa-