Facile isolating of chitin nanofibril from silkworm chrysalis and its potential application in structuring oil

Chitin nanofibrils with micron sized length are successfully isolated from silkworm chrysalis (BoNCh). The chitin fibrils in silkworm chrysalis seem loosely connected with rich pores, which is believed to benefit the nanofibrillation process. Through simple physical crosslinking or direct freeze-drying, chitin nanofibril aerogels/cryogels can be prepared and found effective in structuring oil. The oil absorption capacity (OAC) reaches 95.96 g/g, 149.64 g/g and 172.33 g/g for BoNCh-10, BoNCh-20 and BoNCh-30 based aerogels respectively, while the oil holding capacity (OHC) keeps higher than 68%. Higher deacetylation degree and smaller fibril size lead to increased OAC and similar OHC. What's more, chitin nanofibril cryogels are found more effective in structuring oil. The OAC and OHC reach 234.93 g/g, 151.98 g/g, 103.09 g/g and 58.59%, 74.65%, 76.22% for BoNCh-20 with nanofibril concentration of 0.2%, 0.4%, 0.6% respectively. Compared with cellulose-based aerogels, the aerogels/cryogels prepared in this work possess much higher oil holding capacity, indicating excellent oil adsorption and oil holding capacity for chitin nanofibril. Gel like Pickering emulsions also can be prepared by simply mixing chitin nanofibril suspension and oil followed with ultrasonication treatment. No creaming can be observed after 30-days storage for BoNCh-20 and BoNCh-30 stabilized Pickering emulsion with 0.15% nanochitin. The G′ and G″ of the Pickering emulsions stabilized by BoNCh-10, BoNCh-20 and BoNCh-30 reach 11550.5 mPa, 11751.9 mPa, 9585.4 mPa and 2150.4 mPa, 2543.2 mPa, 2564.8 mPa, respectively, indicating a typical weak gel for all emulsions after 30-day storage. [Display omitted] •Chitin nanofibrils with micron sized length are isolated from silkworm chrysalis.•Chitin nanofibrils (0.15%) are found effective in preparing Pickering emulsions.•OAC and OHC reach as high as 234.9 g/g and 76.2% for chitin nanofibril cryogel.