methoxypyrazines, flavour compounds which result in herbaceousness. They contain nitrogen and are secondary products of amino acid metabolism. Three methoxypyrazines have been identified for Cabernet Sauvignon and Sauvignon Blanc grapes: isobutyl-methoxypyrazine (IBMP), secbutyl-methoxypyrazine (SBMP), and isopropyl-methoxypyrazine (IPMP). Sensory evaluation has confirmed the contribution of IBMP, which has a very low threshold of 215 ng/l in white wine, to the aroma described as characteristic of capsicum or bell pepper and green gooseberries. It is generally the most dominant of the three. IPMP, the most abundant of the three, has a more earthy aroma, characteristic of cooked or canned asparagus (found in some New Zealand Sauvignon Blanc).
