As can be seen, roughly 50% of all nitrogen in the unaged wine is used (particularly l-ornithine, l-leucine, l-methionineand l-proline, which jointly accounted for 81% of the total nitrogen consumption). The proportion in which these compounds were used increased with increasing availability in the wine: l-proline (47.6%) > l-leucine (15.9%) > l-methionine(10.5%) > l-ornithine (6.9%). There was virtually no net formation of amino acids; also, little ammonium ion was consumed despite its availability in relatively large amounts.