Effect of Sonolysis on Acid Degradation of Chitin to Form Oligosaccharides

Abstract

Chitin [partially deacetylated β-(1→4)-linked 2-acetamide-2-deoxy-β-d-glucopyranose, (GlcNAc)n] was hydrolyzed by hydrochloric acid under the ultrasound irradiation. The first seven members of (GlcNAc)n in the degradation fluid were analyzed with high performance liquid chromatography (HPLC). The produced amounts of (GlcNAc)1—7 obtained by the degradation in concd HCl increased almost in proportion to the degradation time up to 120 min when sonolysis was used concomitantly. The yield of saccharides in the degradation fluid by concd HCl with sonolysis was about 2—4 times as much as that in the hydrolysis without sonolysis. The yield(%) increased with increasing of the concentration of HCl (6—12 mol dm−3) but decreased with increase of the concentration of chitin, showing a solvent volume effect. For the production of higher oligosaccharides, such as (GlcNAc)5—7, degradation with sonolysis for not longer than two hours is desirable. Deacetylated products were negligible. The effect of sonolysis is discussed from the aspect of the interactions of water with saccharide chains.

Preparation of Chitin and Chitosan Oligomers and Their Applications in Physiological Functional Foods

“…Chemical methods for the preparation of chitin oligomers include acid hydrolysis (25)(26)(27)(28)(29)(30)(31). Recently, series of chitin oligomers, up to the hexamer, have become commercially available.…”

“…They are usually prepared by partial hydrolysis of chitin with concentrated hydrochloric acid, followed by column chromatographic fractionation (25). The conventional procedure for their isolation is as follows: 1) acid hydrolysis, 2) neutralization, 3) demineralization, 4) charcoal-celite column fractionation, 5) HPLC fractionation, and 6) lyophilization (31). However, such a simple method, using only concentrated hydrochloric acid has several problems such as being time-, cost-and labor-intensive for the fractionation process and affords a low yield of oligomers with a high degree of polymerization (DP).…”

“…However, such a simple method, using only concentrated hydrochloric acid has several problems such as being time-, cost-and labor-intensive for the fractionation process and affords a low yield of oligomers with a high degree of polymerization (DP). Acetolysis (26,30), fluorolysis (27), fluorohydrolysis (28), and hydrolysis with sonolysis (31) have been studied to alleviate these problems (Fig. 1).…”

Cellulose nanofibres by sonocatalysed-TEMPO-oxidation

“…For example, starch is totally depolymerised to glucose under ultrasonic assistance with sulphuric acid as the catalyst (Choi and Kim 1994), even at 23°C (Akiya and Okui 1951;Tomasik and Zaranyika 1995). The hydrolysis and cleavage effect of ultrasound has also been studied on cellulose derivatives and other polysaccharides as chitosan, xanthan, chitin, native cinerean (Chen et al 1997;Berth et al 1996;Takahashi et al 1995;Stahmann et al 1995) and in the case of disaccharides, on sucrose and lactose (Sakakibara et al 1994). Oxidative reactions (Brochette- Lemoine et al 1999Lemoine et al , 2000, acetalization (Hozokawa et al 1958), formation of carbon-carbon bonds could also benefit from sonocatalysis.…”

Produção de quitosanas com características controladas utilizando a irradiação de ultrassom de alta intensidade

“…Devido a essas características grande parte dos estudos envolvendo irradiação de polímeros com ultrassom tem como objetivo principal a despolimerização 109,[116][117][118][119][120][121][122] , enquanto os estudos de irradiação de polímeros em meio heterogêneo para provocar alterações morfológicas nas partículas são menos frequentes 123,124 . …”