| Summary: | 碩士 === 國立海洋大學 === 水產食品科學研究所 === 83 === The extracion yield and emulsifying properties of freeze-dried enzymatic hydrolysate from Monostroma nitidum prepared by various process methods and enzymatic hydrolysis were investigated. The extraction yield increased from 18.0% using no hydrolysis to 64.9% by using a combination of cellulase R-10 (E/S=3.0%) and Macerozyme R-10 (E/S=3.0%) for 3 hr. The emulsifying activity of enzymatic hydrolysate from Monostroma nitidum decreased with hydrolysis time. The Macerozyme R-10 hydrolysis resulted in obvious decrease Increases of carbohydrate content in the low molecular weight area with enzymatic hydrolysis were found by gel permeation chromatography. Monostroma nitidum treated with cellulase R-10 to extract the hot-water soluble enzymatic hydrolysate and spray-dried resulted in 50.0% of polysaccharide and 6.0% of protein. Increasing the hydrolysate concentration of the solution (0~3.0%), the emulsion emulsion stability increased from 7.6 and 5.0% to 54.5 and 49.0%, respectively, and oil was seperated from the emulsion at these concentrations. The solution apparent viscosity and the emulsifying activity, emulsion stability and zeta potential of emulsion at different pH''s were all shown to follow the order of pH 3.0>pH5.0>pH 7.0 By ultrafiltration, the hydrolysate was fractionated into three fractions based on molecular weight: higher than 1,000kd, 10~1,000kd and lower than 10kd. The emulsifing activity was 57.0, 50.0 and 2.0%, and emulsion stability was 51.0, 48.5 and 1.0% respectivly. By dry-heating at 60°C, RH65%, the emulsifying activity and emulsion stability of the conjugates of the hydrolysate increased from 51.5 and 48.0% to 57.6 and 50.0%, respectively. The surface hydrophobicity increased from 44.5 to 156.2 Se/mg/ml. The ratio of protein high/low molecular weight peak area increased from 0.251 to 0.343. Conjugates with bovine serum albumin (BSA), sodium caseinate (SC) and soy protein isolate (SPI) prepared by dry-heating increased the emulsifying activity to 76.4, 79.7and 83.1%; increased the emulstion stability to 74.9, 75.0 and80.8%, and increased the ratio of protein high/low molecular weight peak area to 0.286, 0.334 and 0.443, respectively. When using ethanolic precipitation both emulsifying activity and emulsion stability increased to 69.0 and 62.0%, respectively, and oil was not seperated from emulsion when the concentration was at 1%(w/v). However, the emulsifying activity and emulsion stability of the dried supernate decreased to 42.5 and 40.0% respectively, and the oil layer increased from 1.0 and 2.0% to7.5 and 10.0%, respectively, at the same concentration. Increased protein and carbohy drate content was found by gel permeation chromatography in the high molecular weight area of the ethanolic precipitate. Increasing the ethanolic precipitate concentration of solution (0~20 mg/ml) led to a reduction of surface tension to 54.9 dyne/cm, and the critical micelle concentration was 3.9 mg/ml. The emulsifying activity and emulsion stability increased to 76.9 and 70.0%, respectively,When ionic strength was increased to 0.2 by adding NaCl, the solution apparent viscosity dercreased from 37.1 to 7.6cps; the emulsifying activity and emulsion stability decreased 69.0 and 62.0% to 50.0 and 48.0%respectively;and the zeta potemtial of emulsion decreased from 63.9 to 28.2(-mV).The solution apparent viscosity and emulsifying activity, emulsion stability and zeta potential of emulsion at different pH''s which were controlled by buffer were all shown to follow the order of pH3.0>pH5.0>pH7.0.Using pronase E to hydrolyze the ethanolic precipitate for 3hr, the emulsifying activity and emulsion stability decreased to 61.0 and 56.5%, respectively, and both had 2% oil seperated from emulsion, and the solution apparent viscosity and zeta potential of emulsion decreased to 25.2 cps and 49.2 (-mV), respectively .The ratio of protein high/low molecular weight peak area decreased obviously from 5.13 to 2.95, using enzymatic hydrolysis for 3 hr with pronase E, as shown by gel permeation chromatography.
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