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Effect of maturity and after-ripening on the formation of gel in the syrup made from Japanese apricot ‘Suiko’ fruits

Author:
Tsuchida, Yasuhisa, Onishi, Sayo, Gato, Nobuki, Naka, Yoshiaki, Oe, Takaaki, Jomura, Noriaki
Source:
Scientia horticulturae 2019 v.247 pp. 101-106
ISSN:
0304-4238
Subject:
Prunus mume, after-ripening, esterification, fruits, gels, liquids, odors, pH, pectins, polymers, raw fruit, ripening, syrups, total soluble solids, uronic acids, water solubility
Abstract:
To process clear syrup from ‘Suiko’ Japanese apricots, the effect of fruit changes on the amount of gel with pectin characteristics formed upon natural ripening or after-ripening was investigated. Little gel was formed in the syrup extracted from early-mature fruits subjected to after-ripening for 0 to 4 days, and from moderately mature fruits subjected to after-ripening for 0 to 2 days; conversely, a large amount of gel was formed in the syrup extracted from fully mature drop fruits. Uronic acid was found at a higher concentration and had a higher degree of esterification in the gel than in the liquid phase. Moreover, the gel contained larger amounts of high-molecular-weight polysaccharides than the liquid phase. In raw fruits, an increase in the duration of natural ripening and after-ripening reduced high-molecular-weight water-soluble pectin content, and increased the low-molecular-weight polymer. This suggests that low-molecular-weight pectin would actively convert into syrup in ripened fruits, while high-methoxyl pectin would recombine under conditions of low pH and high soluble solid content, thus resulting in gel formation. We conclude that early-matured fruits after a 4-day after-ripening treatment were best suited for processing because they showed the least gel formation in the clarified syrup, while preserving aroma.
Agid:
6251989