Apple Juice Clarification Using Microfiltration and Ultrafiltration Polymeric Membranes

The ripening of Emmental cheese samples from 30 dairies was followed over 12 months. Biochemical, chemical, microbiological, rheological and sensory properties were measured. Only a few parameters measured at 1 and 20 d could predict flavour and texture development after 3, 6 and 12 months. The sum of free amino acids measured after 1 d with the Cd ninhydrin method correlated with the index of maturity, intensity of aroma, saltiness and sourness from 3 months. The TCA-soluble nitrogen (TCA-SN) after 20 d allowed the same prediction. Lysine aminopeptidase (LAA) after 20 d correlated positively with the index of maturity and saltiness after 3 months, and negatively with sweetness at 3 months and bitterness after 1 y. Higher proline aminopeptidase (PAA) values after 20 d were a good indicator for a pronounced sourness after 3 and 6 months. The higher the content of free amino acids after 1 d, the lower the firmness, stress and strain at fracture (up to 6 months). Strain at fracture could also be estimated by PAA after 1 d, LAA or TCA-SN after 20 d. All correlations were negative. Stress at 33% deformation correlated positively with LAA (up to 6 months) and TCA-SN (up to 12 months) after 20 d.