Published online by Cambridge University Press: 01 June 2009
The results reported suggest that it is possible to follow the ripening of Parmesan cheese by means of histochemical reactions for proteins, glycoproteins, acid mucopolysaccharides and lipids containing choline.
The blue colour, formed when the proteins of the curd were stained with Bonhag's reagent, slowly turned to violet and then to red as ripening progressed.
Glycoproteins and acid mucopolysaccharides, although present in very small amounts, appeared to be a constant characteristic of the cheese.
Lipids containing choline, which were absent from the curd, were clearly visible in 3 to 7-month-old cheese. They then decreased and were absent in the ripened cheese.