Changes in flesh firmness, alcohol-insoluble substances (AIS), total pectic substances (TPS), and cell wall hydrolases of ´Tsugaru´, ´Jonagold´ and ´Fuji´ apple fruits during ripening and storage were investigated.
Flesh firmness was rapidly declined in ´Tsugaru´ and ´Jonagold´, while slowly in ´Fuji´ during ripening and storage. Among the cultivars the contents of AIS, TPS and insoluble pectic substances (IPS) were highest in ´Tsugaru´ and lowest in ´Fuji´ and they declined greatly until the harvesting time. However, contents of AIS, TPS, and IPS were not changed during storage of ´Jonagold´ and ´Fuji´ apples, while they declined continuously up to 40 days after initiation of storage in ´Tsugaru´. Water-soluble pectin (WSP) declined until the harvesting time, while increased during the storage. WSP contents of fruits before harvest were highest in ´fsugaru´ and lowest in ´Jonagold´ among the cultivars. No differences were observed in WSP between ´Tsugaru´ and ´Fuji´ during storage, whereas WSP contents were significantly lower in ´Jonagold´. Versene -soluble pectin (VSP) declined through the maturation, but slowly increased during the storage. In general, VSP in ´Fuji was higher than in ´Tsugaru´ and ´Jonagold´ during the storage. Activity of β-galactosidase increased continuously during the maturation and storage, and the rate of increase was highest in ´Tsugaru´ Activities of polygalacturonase (PG) in all cultivars were very low through 20 days before harvest, while they were highest at harvesting time in ´Tsugaru´ and ´Jonagold´ and at 20 days after initiation of storage in ´Fuji´, and then declined in all cultivars. Pectinmethylesterase (PME) activity was declined with fruit maturation in all cultivars, and ´Tsugaru´ and ´Jonagold´ showed higher activities of that than ´Fuji´. However PME activity of ´Fuji´ compared to ´Tsugaru´ and ´Jonagold´ increased significantly during storage.
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