Role of precursors on greening in crushed garlic (Allium sativum ) bulbs, and its control with freeze-dried onion powder

BACKGROUND: Lachrymatory factor (LF) synthase in onion bulbs reacts with S-1-propenyl-L-cysteine sulfoxide (1-PeCSO), a key compound in garlic greening. In this study, freeze-dried onion powder containing LF synthase was used in treatments to control garlic greening. Prior to the use of freeze-dried onion powder to treat greening garlic bulbs, model reactions were conducted to confirm the reactivity of 1-PeCSO in onion bulbs to garlic greening. RESULTS: While pink pigments were generated from 1-PeCSO, green pigments were produced from the combination of 1-PeCSO and S-2-propenyl-L-cysteine sulfoxide (2-PeCSO). However, pigments were formed in the systems containing 1-PeCSO, amino acid and alliinase. Even non-greening garlic bulbs stored at 20 °C turned green with the reaction of 200 g L−1 1-PeCSO; therefore 1-PeCSO isolated from onion bulbs had the same role as 1-PeCSO in garlic bulbs in terms of greening. Onion bulbs turned green after the addition of 600 g L−1 2-PeCSO. The addition of freeze-dried onion powder inhibited garlic greening, and treatment with 15 g kg−1 onion powder gave the best storage stability of crushed garlic bulbs. CONCLUSION: The addition of freeze-dried onion powder inhibited the greening in crushed garlic bulbs, and treatment with 15 g kg−1 onion powder gave the best storage stability of crushed garlic bulbs. Copyright © 2011 Society of Chemical Industry