To study the relationships between various components and the hardness of 'Koumezuke' [a small type mume (Japanese Apricot,
Prunus mume SIEB, et Zucc)], we analyzed the Ca, Mg and pectin content, and also measured the hardness of 'Kaoumezuke' that has been brined at various factories. The binding properties of Ca or Mg to certain components of AIS (alcohol insoluble substances) in two different types of pickled mume fruit, 'Koumezuke' (a salted product) and 'Koumeboshi' (a dried salted product), were characterized as Ca >> Mg. In 'Koumezuke', the ratio of HSP (0.05N-hydrochloric acid-soluble pectin) against total pectin decreased and PSP (0.4%-hexametaphosphate-soluble pectin) increased during brining and both ratios showed a slight change after the eighth day of brining. The HSP/WSP (H/W) ratio of 'Koumezuke' and 'Koumeboshi' was 10.1 and 0.48, respectively. The HSP of Koumeboshi was hydrolyzed by acids concentrated during a sun-dried process, and HSP changed mainly to WSP, and the mume fruit softened in texture. There was a significant correlation between the hardness and H/W ratio of 'Koumezuke' at 1% level significance. In the cases where H/W ratio was under 16, coefficient correlation (r) was found to be 0.972, and a simple regression equation was H = 51.4R +186. No significant correlation was found between the content of Ca, Mg and the hardness of 'Koumezuke.' 'Koumezuke' softened in texture when the fruit was stored in solution containing a salt concentration of less than 10.7%, an acid concentration of more than 2%, and at temperatures above 30°C 'Koumezuke' softened in texture by the addition of organic acids in the order of citric acid> malic acid>lactic acid.
View full abstract