Combined use of waste materials - recovery of chitin from shrimp shells by lactic acid fermentation supplemented with date juice waste or glucose

BACKGROUND: Chitin, a source of chitosan, was extracted from the teguments of white shrimp Parapenaeus longirostris, by means of Lactobacillus helveticus growing on date juice waste or glucose for comparison. A fermentor containing 10% (w/v) of shrimp shells was inoculated with a suspension of L. helveticus strain milano (10% v/v). RESULTS: For an initial pH of 8.5-9.0 and a temperature of 30 degrees C, maximum deproteinization and demineralization were 76 and 53%, achieved for 80 and 300 g L-1 glucose, respectively. The level of demineralization increased to 60%, for an increase in in temperature from 30 to 35 degrees C. The use of date juice, as an alternative to the use of a primary carbon source such as glucose, led at best to 44% demineralization, for 208 g L-1 of total sugar at 35 degrees C, and 91%, deproteinization, for 80 g L-1 total sugar content at 30 degrees C. CONCLUSION: Demineralization was not improved by the use of date juice, most likely due to its calcium content, which, during acidification, prevents the diffusion of calcium from the shells to the surrounding medium. Contrarily, the proteolytic activity of LAB appeared to be improved by the mineral content of date juice, leading to almost complete deproteinization of shrimp shells. (C) 2008 Society of Chemical Industry