Abstract
Alfalfa leaf extracts were prepared by disintegrating fresh herbage, coagulating the green juice by steam injection and separating the curd from the deproteinized juice. Addition of ethoxyquin (w/v) into the green juice at 0.01%, 0.02%, 0.05%, 0.10% and 0.20% levels prior to coagulation gave final concentrations of 0.11%, 0.26%, 0.70%, 1.15% and 2.57% in the freeze dried leaf extract, respectively. Samples, packed in vinyl bags and wrapped in aluminum foils, were stored for 40 weeks at 28℃, 5℃ or -18℃. The lower the storage temperature, the lesser the reduction in carotenoid content was. The rate of loss of β-carotene was much faster than xanthophylls. At high temperature (28℃), ethoxyquin was essential to reduce the loss of carotenoids. Without it, recoveries of β-carotene and xanthphyll in leaf extract were reduced to 3 and 15%, respectively, of the initial values within 40 weeks, but were improved to 30 and 50% by the addition of only 0.01% ethoxyquin. Further addition improved the recoveries a little further to 50 and 60%, respectively, at the highest application level. At low temperatures (5 and -18℃), carotenoids were well preserved without ethoxyquin excepting β-carotene at 5℃. The recovery of β-carotene at 5℃ was only 40% but was improved gradually to 90% with the increase of ethoxyquin levels. The decline of ethoxyquin in leaf extract at temperature above freezing implies that ethoxyquin itself be subjected to degradation. Only slight difference was ob-served between 5℃ and 28℃ in the ethoxyquin degradation.
