Study of Microwave on Freeze-Drying and Oil Extraction of Krill

• Main Authors: Hao-Cheng, Chang, 張浩誠
• Other Authors: Su-Der, Chen
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/h9kx69

碩士 === 國立宜蘭大學 === 食品科學系碩士班 === 104 === Krill oil contains a lot of long-chain polyunsaturated fatty acids (LC-PUFAs, such as: DHA, EPA) attached to the phospholipid and rich in astaxanthin. Therefore it is easier to be absorbed by the human body and surpasses fish oil in physiological activity. The fresh krill must be frozen-dried to remove moisture before oil extraction in order to avoid autolysis. However, poor heat transfer efficiency results in poor process efficiency of freeze drying and extraction. Microwave can overcome heat transfer resistance; therefore, the aim of this study was to investigate the microwave application on the freeze-drying krill and extraction oil for improving process efficiency. The results showed that DHA extraction yield of fresh krill by microwave extraction increased from 8.14 to 11.68 mg/g with increasing to ratio of solid and liquid from 1:4 to 1:12. The DHA extraction yield decreased with increasing time and microwave power due to oxidation during microwave extraction. The vacuum microwave extraction system significantly increased the DHA extraction yield than microwave extraction. Increasing microwave power (X, (W)) increased drying rate (Y, (g/hr)) for microwave freeze-drying 50 g krill, and the linear relationship was Y = 0.6014X - 3.7847, r2 = 0.9919. When the microwave power increased from 50 to 90 W, the drying rate of krill increased from 25.54 to 48.82 g/hr; therefore, it reduced about twice drying time. In the calculation of energy consumption, the energy consumption of conventional freezing drying (FD) took about 34651 kJ for 15 hr drying, and 90 W microwave freeze-drying (MWFD) 44 min only required 1995 kJ; therefore, it saved 95% energy. The DHA contents of FD and MWFD krill were 8.59 and 7.57 mg/g, respectively.