Isolation and identification of causal constituents of green discoloration in garlic puree

Abstract

The green discoloration of garlic (Allium sativum L.) puree, a serious problem in garlic processing, was investigated. Two thiosulfinates, 2-propenyl E-1-propenethiosulfinate (2P1PTS) and (E/Z)-1-propenyl 2-propenethiosulfinate (1P2PTS), were isolated from unheated garlic puree (homogenate), and were confirmed to be the direct causal constituents ('color developer') of green discoloration based on a color developing assay. 2P1PTS and/or 1P2PTS were reacted with glycine to develop a blue-green color similar to the discoloration of garlic purees. 2P1PTS and 1P2PTS showed synergy for greening; the color developing activities of three solutions, 2P1PTS, 1P2PTS and an equimolar mixture of them (0.5-2P1PTS + 0.5-1P2PTS; similar to the natural abundance ratio) were in the rank order: (0.5-2P1PTS + 0.5-1P2PTS) > 2P1PTS > 1P2PTS. © 2012 Food Sci. Technol. Res.