蜗牛酶改性金针菇不溶性膳食纤维工艺优化及其对理化性质的影响

Optimization of Snailase Modification of Flammulina velutipes Insoluble Dietary Fiber and Its Effects on Physicochemical Properties

用蜗牛酶(snailase)对金针菇(Flammulina velutipes)不溶性膳食纤维(insoluble dietary fiber,IDF)进行改性,以改性后可溶性膳食纤维(soluble dietary fiber,SDF)得率为指标,通过单因素实验和正交实验确定最佳工艺参数,并测定不同SDF含量改性膳食纤维的理化性质。结果表明:利用蜗牛酶改性金针菇IDF的最佳工艺参数为蜗牛酶使用量2%、酶解时间14 h、酶解温度35℃、pH7.0,该条件下SDF得率为14.38%;与未改性样品相比,改性后样品SDF含量增加363.87%;改性后样品的持水力、持油力、膨胀力、阳离子交换力、葡萄糖吸附能力、葡萄糖透析延缓能力、胆固醇吸附能力、DPPH自由基清除能力随着SDF含量的增加而增加。红外光谱分析表明,改性前后的样品均在3400、1739、1000~1300 cm^(-1)有糖类的伸缩振动特征峰,但改性后样品的透射率明显低于未改性样品。扫描电镜和粒度分布分析结果表明,改性膳食纤维出现大量片层以及少量蜂窝结构,整体结构疏松,比表面积增大,且随着样品中SDF含量增而更明显。X射线衍射分析表明,蜗牛酶改性处理未使金针菇IDF的晶体构型发生变化,仅衍射强度有所减弱。研究结果表明,蜗牛酶能使金针菇不溶性膳食纤维中的葡聚糖及半纤维素发生分解,从而提高其可溶性,改善其理化性质。

In order to increase soluble dietary fiber(SDF) content in Flammulina velutipes,its insoluble dietary fiber(IDF) was modified by snailase.Using SDF yield as the index,the technological parameters of snailase modification were optimized by single factor and orthogonal experiments.The modified dietary fiber samples with different SDF contents were determined for physicochemical properties and analyzed for structure.The results showed that the optimal conditions for IDF sanilase modification were using 2% snailase to hydrolyze under 35 ℃ and pH7.0 for 14 h,and the resultant SDF yield was 14.38%.Compared with unmodified IDF,the SDF content of the modified IDF derived under the optimal conditions increased by 363.87%.There were significant increases of water holding capacity,oil holding capacity,swelling capacity,cation exchange capacity,glucose adsorption capacity,glucose dialysis retardation index,cholesterol adsorption capacity and DPPH free radical scavenging capacity in the snailase modified IDF in a SDF content dependant manner.The Fourier transform near-infrared spectroscopy(FNIR) results showed that there were characteristic peaks 3 400 cm^(-1),1 739 cm^(-1) and 1 000-1 300 cm^(-1) in the IDF samples regardless of modification.However,the transmission of the modified IDF was significantly lower than that of the unmodified IDF.Scanning electron microscopy and particle size distribution analysis showed that the snailase modified IDF had a overall loose structure with a large number of lamella and a small amount of honeycomb structure,and its specific surface area was increased compared with the unmodified IDF.These structural changes were more obvious as the SDF content increased.X-ray diffraction analysis showed that the crystal configuration of F.velutipes IDF remained the same after snailase modification,with a slight decrease in diffraction intensity.These results suggested that snailase partially hydrolyzed glucan and hemicellulose in the insoluble dietary fiber of F.velutipes,thus increasing the content of soluble components and improving the physicochemical properties of F.velutipes dietary fiber.