Study On The Fruits Preservation With Oyster Shell Powder

Oyster, a cosmopolitan shellfish, belongs to mollusk phylum. It has been discovered more than one hundred kinds in the world at present and is possessed by nearly all the coastal countries, which are distributed in Chinese coastal cities for more than twenty kinds. Oyster is profoundly popular with customers for its tasty flavors and abundant nutriments. However, a great number of shells are thrown away as rubbish after eating. The research and development presently of oyster shells is limited in medicine, health care, food additives, etc. but is lack of uses in the preservation of fruit besides a rough report on patent of Japan. The rough report said that oyster shell owns power of sterilization and adsorption. But there are not any detail research report. Therefore, it has yet to be researched, developed, and employed.The main factor leads to the decay of fruit is the microorganism, which destory the histocyte of fruits.And the fruits would be deformated and soften. The existence of ethylene, a kind of plant hormone, quickens up the maturity, consenescence and deterioration of most of the fruits. The oyster shell contains substantive calcium carbonate and some carapace elements. When the carapace elements are taken off the acetyl, it forms the chitin, which owns great power of sterilization. Meanwhile, the physical formation of the oyster shell is made up of stratum of keratose, prism and pearl, in which the main part is the stratum of prism. It contains lots of micropore from 2 to 10μm. The special micropore formation is benefit for the deep diffusion to pore of ethylene and easy to be absorbed by the reactive surface, which is possessed of great power of adsorption. Therefore, the thesis discusses the application of the shell powder in the preservation in fruit, also analyzes antibacterial property and the capability of adsorption, make it be used to the preservation of bananas and Chinese gooseberry with oyster shell as material. Here are the main research outcomes:(1) Different treatment of oyster shells powder can greatly inhibit the growth of Penicillium italicum Wehmer, Aspergillus niger and Rhizopus stolonifer. It is best for the inhibition of the Rhizopus stolonifer of and Aspergillus niger in dealing with 0.4 %HCl or 1.4 % NaOH of oyster shell. And the form of inhibition to Penicillium italicum Wehmer is the dealing with 0.6 %HCl and 1.2 %NaOH of oyster shell powder.(2) Ethylene could be adsorbed by different treatments of oyster shell powder. The prominence of it is the ball milling, then respectively the treatment of calcining, untreated, 0.4 %HCl and 1.4 %NaOH.(3) The antistaling agent of oyster shell powder can be used in the banana preservation. The effects of preservation of ball milling of it are evidently better than other treatments, which can lessen the density of ethylene, postpone the peak of respiration variance, decline the respiration power, meanwhile reduce the degradation of chlorophyll and the loss of PPO activity, decrease SOD activity, and preserve banana well.(4) The antistaling agent of oyster shell powder can be used in the preservation of the kiwifruit. The effects of preservation of ball milling of it are evidently outstanding, which extend the preservation circle, inhibit the increase rate of weight loss and the total contents of sugar, and reduce the reduction of the contents of Vc and the hardness of the fruit.