AROMA ACTIVE NORISOPRENOIDS IN ORANGE AND GRAPEFRUIT JUICES

摘要

Norisoprenoids are C9-C13 fragments from carotenoid plant pigments that are extremely potent odorants. Norisoprenoids have been identified as aroma impact compounds in a wide range of beverages, foods and spices, including, tea, tomato, and saffron. Orange juice aroma is the result of a complex mixture of volatiles which lacks a specific character impact compound. Numerous studies have identified and quantified the major volatiles in orange juice in an effort to duplicate this aroma. However, when combined, the volatiles present at the highest concentrations did not duplicate orange juice aroma, suggesting that essential aroma components were missing. Citrus carotenoids have been studied primarily for their role as pigments and have generally been ignored as a source of aroma compounds. Known carotenoid norisprenoid precursors such as beta-carotene, alpha-carotene, neoxanthin, beta-cryptoxanthin, lutein, violaxanthin and canthaxanthine have been identified in orange juice using HPLC. Lycopene and P-carotene are the major carotenoids in Ruby red grapefruit juice. Since orange and grapefruit juice contain carotenoids with the necessary structural features which could act as norisoprenoid precursors, we hypothesize that there may be additional norisoprenoids present in these juices. Grapefruit juice should have fewer norisoprenoids than orange juice because fewer carotenoids are present.