Studies on the Preparation of β-chitin from Squid cartilage with Ultrasonic Extraction
Abstract: Chitin is a kind of natural linear polysaccharide polymer made from the N-acetyl-D-glucosamine by β-1, 4 glycosidic bond . This study researches the effects of ultrasonic to the β-chitin preparation process with squid cartilage as raw material, and the process conditions of squid cartilage removal of protein and salt removal were optimized. By a series of single-factor tests and orthogonal trials, the study is not only discuss the impact of the ultrasonic frequency, the concentration of sodium hydroxide, sodium hydroxide liquid ratio, ultrasonic time, ultrasonic temperature to remove protein from squid cartilage, but also to explore the ultrasonic frequency, concentration of hydrochloric acid, hydrochloric acid liquid ratio, ultrasonic time, ultrasonic temperature on the removal of inorganic salt squid cartilage. the products and the chitosan made from them were analyzed with infrared spectroscopy. The results show that the optimum conditions for the removal of proteins as follows: the ultrasonic frequency is 25 KHZ, the sodium hydroxide concentration is 15%,the liquid ratio is 1:10 , the ultrasonic temperature is 60 ℃ and extraction time is 30 min. The optimum conditions for salt removal is showed : the ultrasonic frequency of 70 KHZ, 8% concentration of the hydrochloric acid, 1:14 of liquid ratio, 60 ℃ of the ultrasonic temperature and 40 min of the extraction time. The infrared spectra show that the product prepared by this method is chitin and has the high purity ,and on the same preparation process conditions of chitosan, the chitosan with ultrasound-assisted preparation of chitin is obtained a higher purity of chitosan and a higher degree of substitution, compared with the preparation of chitosan with no ultrasound-assisted preparation of chitin.
Keywords：chitin; ultrasonic wave; removal of protein; salt removal; infrared spectrum analysis
