| Tremella fuciformis,as a kind of edible fungus with the same origin of medicine and food,has high nutritional value and medicinal functions.Due to the high moisture content of fresh tremella and perishable,the commercial tremella products are mainly dry products.Although dried tremella prolongs the shelf life,the dried tremella is light in weight but large in volume,which is not conducive to transportation.Tremella powders can be made by drying and crushing which can be easily packaged and transported,improve nutritional value,and has a good prospect.Therefore,this paper has carried out the study of ultra-micro-pulverization of tremella,and the main research results are as follows:First of all,the tremella was treated by high-speed grinder,and the crude powder was used as the control group(0 Hz).At the same time,the dry tremella was ultrafine crushed under the conditions of different classifier frequencies(10 Hz,20 Hz,30 Hz,40 Hz)by low temperature impact grinding.The color,particle size,basic composition,water holding capacity and oil holding capacity of tremella powders processed by the control group and low temperature impact grinding with different classifier frequencies were measured.Finally,the structure and thermodynamic properties of tremella powders were analyzed by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),differential calorimetry scanning(DSC)and thermogravimetric analysis(TGA).The results showed that with the increase of classifier frequency,the color of tremella powders changed,showing an increase in L* value(85.39-92.23),a*value(4.67-1.04),and b* value(25.40-14.58).The particle size was significantly decreased(389.0-47.7 μm).Water content decreased;The ash and protein contents were unchanged.The fluidity of the powder became worse,showing that the vibration density increased first(0.79-0.86 g/m L)and then decreased(0.86-0.57 g/m L),the bulk density gradually decreased(0.72-0.34 g/m L),and the Angle of reposition gradually increased(21.02°-37.40 °).The hydraulic holding capacity increased gradually(2.90-3.63 g/g),and the oil holding capacity increased gradually(2.67-3.36 g/g).FTIR and XRD results showed that the amorphous structure of tremella powders did not change when it was treated with low temperature impact grinding at different classifier frequencies.DSC and TGA results showed that the thermodynamic properties of tremella powders were not changed by low temperature impact grinding with different classifier frequencies.Secondly,polysaccharides(TFP)were extracted from Tremella fuciformis powder in the control group and from Tremella fuciformis powder with different frequency of low temperature impact milling.The yield,neutral sugar content,uronic acid content,protein content,Zate potential,relative molecular weight,monosaccharide composition,rheological properties,infrared properties and thermodynamic properties of TFP were determined.The results showed that with the increase of the frequency of low temperature impact mill,the yield of tremella polysaccharide gradually increased(2.81-11.48%).The content of neutral sugar gradually increased from 59.16 to 74.12%.The content of uronic acid first increased(18.74-28.60%)and then decreased(28.60-24.17%).The content of polysaccharide protein gradually decreased(0.67-0.29 g/g).The absolute value of polysaccharide Zeta potential increased gradually(39.33-45.40 m V).The molecular weight of polysaccharide gradually decreased(2.20× 107-1.58×107 Da).FTIR and XRD results showed that TFP obtained at different classifier frequencies did not produce new functional groups.DSC and TGA results showed that the thermodynamic properties of tremella polysaccharide did not change within the measurement range.The rheological results showed that the polysaccharide solutions were all non-Newtonian fluids.When the concentration of tremella polysaccharide was greater than 0.5% and the frequency of low temperature impact mill was 20 Hz,the obtained polysaccharide had the highest viscosity.Finally,based on viscosity comparison,Tremella polysaccharide under the condition of low temperature impact mill classifier frequency of 20 Hz was selected to prepare tremella polysaccharide jelly.The results of single factor and response surface experiments showed that the properties of the prepared tremella polysaccharide jelly were the best under the conditions of 1.68% of tremella polysaccharide mixed gum,1:2.98 of kenjac gum and pectin,0.59% of tremella polysaccharide and 10% of white sugar.The sensory evaluation results showed that the hardness of tremella polysaccharide jelly was moderate and the taste was good.Microbiological tests were in line with national standards. |
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