Main content area

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

Tsuchida, Yasuhisa, Onishi, Sayo, Gato, Nobuki, Naka, Yoshiaki, Oe, Takaaki, Jomura, Noriaki
Scientia horticulturae 2019 v.247 pp. 101-106
Prunus mume, after-ripening, esterification, fruits, gels, liquids, odors, pH, pectins, polymers, raw fruit, ripening, syrups, total soluble solids, uronic acids, water solubility
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.