EFFECTS OF MATURITY OF UME FRUIT AND AMOU NTS OF CALCIUM HYDROXIDE INBRINE ON SHRINKING OF HARDENED BRINED UME FRUIT

It is generally accepted that brined ume fruit treated with Ca(OH)2 be comes hard in texture, though in some cases wrinkles appear on the pee l of the brined fruit. The hardened brined ume fruit having wrinkles i s known as shrunk fruit. Since the reason for this phenomenon hasn't b een clarified, we thought that it was very important to research the m echanism of the shrinking of the hardened brined ume fruit. In this pa per we report the relationships between the shrinking, maturity of fre sh ume fruit, and the amount of Ca(OH)2 added as a hardening agent, an d speculate the mechanism of the shrinking. The results obtained were as follows : (1) Scanning electron microscopic observation showed that shrinkage of the fruit was a result of shrinkage of cells. (2) The sh runk fruit occurred when ume fruit used as materials was unripe, and t he additional amount of Ca(OH)2 was in small quantity. (3) The NaCl fa iled to permeate the ume fruit in sufficient amounts, and the acid flo w from the fruit was greatly restricted. (4) The peel of the shrunk um e fruit contained markedly larger amounts of Ca than the flesh, wherea s that of the hardened brined fruit contained the same amounts of Ca i n both peel and flesh. (5) The flesh of the shrunk fruit contained a h igh ratio of water soluble pectin (WSP), but the hardened brined ume f ruit contained very little WSP. As a result, it was found that the shr inking of the hardened brined ume fruit occurred when unripe ume fruit was used as a material and the added Ca(OH)2 was in small amounts. It was presumed that the shrinking might occur by the change of permeabi lity of peel resulting from the difference in tissue structure of the peel and flesh.