低温冲击磨处理对银耳及其多糖性质的影响

Effects of low-temperature impact milling treatment on the properties of Tremella fuciformis and its polysaccharides

【目的】探究低温冲击磨超微粉碎处理对银耳及其多糖性质的影响,以期为银耳的精深加工及活性成分提取提供理论依据。【方法】利用低温冲击磨的不同分级机频率(10、20、30和40 Hz)粉碎干燥银耳,并通过水提醇沉法提取银耳多糖,对不同银耳粉的基本营养成分、物理性质及银耳多糖的基本理化性质、流变特性、结构等进行测定,探究分级机频率对银耳粉及其多糖的影响。【结果】随着分级机频率的增加,银耳粉的水分含量(10.41%~12.18%)逐渐降低,而蛋白质和灰分含量无显著差异(P>0.05);银耳粉颜色由黄色逐渐变为白色,表现为L^(*)增加、a^(*)和b^(*)均降低;平均粒径D_(50)(47.7~389.0μm)显著降低(P<0.05),持水力(2.90~3.63 g/g)增加,持油力(2.67~3.36 g/g)增加,粉末流动性降低。与未经低温冲击磨处理银耳粉提取多糖的性质相比,低温冲击磨处理后银耳粉提取多糖的得率(5.23%~13.88%)及中性糖(63.71%~74.12%)、糖醛酸(24.17%~28.60%)含量增加,蛋白质含量(0.29~0.65 g/g)降低。此外,分级机频率为30 Hz时,多糖的分子量最低,为15400 kD;不同银耳多糖均以甘露糖为主要单糖,其余由核糖、鼠李糖、葡萄糖醛酸、半乳糖醛酸、葡萄糖、半乳糖、木糖、岩藻糖组成。多糖Zeta电位绝对值随分级机频率增加整体呈增加趋势。流变特性测定结果表明,不同银耳多糖溶液均属于非牛顿流体,且分级机频率为20 Hz时,溶液的黏度最高。红外光谱及X射线衍射结果表明,不同分级机频率银耳粉提取的多糖均不会产生新官能团,为无定型结构。【结论】低温冲击磨粉碎能改善银耳粉色泽,改变银耳粉粒径及流动性,提高多糖得率,也影响银耳多糖的流变性质,但不会改变多糖的单糖组成和基本结构。

【Objective】To investigate the effects of low-temperature impact milling on the properties of Tremella fuciformis powders and T.fuciformis polysaccharides(TFP),with a view to providing theoretical basis for the deep processing of T.fuciformis powders and the extraction of active ingredients.【Method】Different classifier frequencies(10,20,30 and 40 Hz)of the low-temperature impact mill were used to crush the dried T.fuciformis,and TFP were obtained by water extraction and alcohol precipitation method.The basic nutrients,physical properties of different T.fuciformis powders and the basic physicochemical properties,rheological properties and structure of TFP were determined to investigate the effects of classifier frequency on T.fuciformis powders and TFP.【Result】As the frequency of the classifier increased,the moisture content(10.41%-12.18%)of T.fuciformis powders gradually decreased,while there was no significant difference in protein and ash contents(P>0.05);the color of T.fuciformis powders gradually changed from yellow to white,which showed an increase in the L^(*)value,and decrease in the a^(*)and b^(*)values.The average particle size D_(50)(47.7-389.0μm)was significantly reduced(P<0.05),the water holding capacity(2.90-3.63 g/g)and oil holding capacity(2.67-3.36 g/g)were increased,and the powder fluidity was reduced.Compared with the polysaccharide properties extracted from T.fuciformis powders without low-temperature impact milling treatment,the polysaccharide yields(5.23%-13.88%)obtained using the treated T.fuciformis powders,the content of neutral sugars(63.71%-74.12%)and glucuronic acid(24.17%-28.60%)were increased,while the protein content(0.29-0.65 g/g)was reduced.In addition,the lowest molecular weight of the polysaccharides was 15400 kD at a classifier frequency of 30 Hz;all the different TFP had mannose as the main monosaccharide,and the rest consisted of ribose,rhamnose,glucuronic acid,galacturonic acid,glucose,galactose,xylose,and fucose.The absolute values of polysaccharides Zeta potential increased gradually with the increase of frequencies of classifier.The results of rheological characterization showed that the different TFP solutions were all nonNewtonian fluids,and the viscosity of the solutions was the highest when the classifier frequency was 20 Hz.Infrared spectroscopy and X-ray diffraction showed that the polysaccharides extracted from T.fuciformis powder with different classifier frequencies did not produce new functional groups and were amorphous.【Conclusion】Low-temperature impact milling can improve the color of T.fuciformis powder,change the particle size of T.fuciformis powder as well as the fluidity,improve the yield of polysaccharide,also affect the rheological properties of TFP,but will not change the monosaccharide composition and basic structure of the polysaccharides.