| Rice,as an important food crop,is indispensable in people's life world.In China,rice processing is in a primary state and the overall utilization of resources is lower.There are increasing demands for pure rice starch all over the world.But,the production and deep processing are lag behind in corn and potato starch industry.Glutinous rice starch has superior application characteristics and is more popular among rice starch varieties because of its special structure.It's worth noting that there are 30%proportions of rice flour byproducts in the rice starch product processing.Therefore,it is important for the economic benefits of rice starch product processing technology that whether the byproduct of rice starch processing technology can be utilized efficiently.In view of the above problems,firstly this research studies the interaction force between starch and protein and its effect on property changes in glutinous rice.And then,optimizing the separation processing conditions and the properties changes in the separation processing.The separation parameters of cyclone are optimized numerical simulation by CFD software.Finally,the effects of protein content on property changes of glutinous rice are studied.The detailed summaries of the results are as follows:Addition of SDS,urea,L-Cys,NaCl,acid and base solution to the glutinous rice slurry system acting as hydrophobicity,hydrogen bond,di-sulfur bond,electrostatic force and spatial steric effect to study the effects of interaction forces on physic-chemical properties,thermo-mechanical properties,and chemical structure changes in glutinous rice flour.Results showed that addition of urea led to a weakening in hydrogen bonds,thus promoting starch and protein leaching into solution and decreasing by 2.4%and 9.0%compared with that of the control.The solubility at 90°C was increased from 42%to 71%after urea treatment.Dynamic rheometer was used to investigating the viscoelastic properties and resistance to deformation or shearing.Addition of urea led to a more weak network that the tan?value?F=1 Hz?increased by 8.8%,the shear strain value(shear velocity=100 s-1)decreased by 52%,and the elastic recovery ability decreased by 6.2%comparing to the control.There were negative effects on pasting properties among SDS and urea.SDS had positive effects on viscosity values and the viscosity values of glutinous rice flour treated with SDS were significantly higher than that of the control?ranging from 7.8%to 11.6%?.On the contrary,urea treatments had negative effects and the addition of urea significantly decreased the peak,trough,and final viscosity values of curve by 14.9%,9.1%,and 15.9%,respectively,compared with that of the control.The addition of NaCl promoted protein leaching into the solution and the starch content increased.Protein content of glutinous rice flour decreased by 4%and starch content increased by 3%after NaCl treatment comparing to the control.Rheometer results showed that addition of NaCl led to a more stable structure of glutinous rice flour that the tan?value?F=1 Hz?decreased by 15%,and the shear strain value(shear velocity=100 s-1)increased by 8%compared to the control.Observed from Raman scans,all treatments led to obvious changes in glycosidic linkage and changes in hydrogen bond network,resulting in changes in the order and crystallinity of starch molecules.After three kinds of proteases treatments,the solid part of glutinous rice slurries were quality equally divided into three parts?named upper,middle,and lower layer?according to color differences.Impacts of three kinds of proteases on chemistry composition,physic-chemical properties,water distribution,interaction forces and their relationships of the three layers of glutinous rice flours were investigated.Results showed that there were obvious differences in chemical compositions of the three layers.The changes of protein and ash content were the same and the values followed by the trend:upper>lower>middle.But the starch content showed opposite trend.The effects of three kinds of proteases on property changes of three layers in glutinous rice flours were differences.Protein and ash content decreased with proteases treatments as the glutinous rice flours became brighter and less yellow,and the values were changed by 0.7%0.9%,0.1%0.2%,0.6%1.2%and 15%27%,10%17%,29%46%,respectively for the upper,middle,lower layer compared to the control.The cumulative ratios of glutenin and albumin in each layer of the control group were higher than 85%.The proportions of prolamin in each layer of glutinous rice flours were increased by proteinases hydrolysis preparation.The amounts of prolamin in the middle layers of glutinous rice flours increased significantly from 9%to 33%46%after proteinases hydrolysis preparation.The amounts of hydrophilic groups and hydrogen protons in the glutinous rice flour were increased after proteinases hydrolysis preparation,which resulting in significant increases in transpanrency and solubility.Transparency of the lower layer in glutinous rice flour had the smallest value,which changed from 2.6%to 4.7%.S-H and S-S content were closely related to the protein content changes.Protease treatments significantly?p<0.05?decreased total S-H and S-S content,and increased free S-H content.Values of total S-H and S-S contents of middle layers were decreased by 53%68%and 60%66%,and the free S-H contents of lower layers were increased by 92%93%compared to the control.The network structure of glutinous rice flour was maintained by protein through hydrophobicity interaction,especially in the upper layers,and the protein dissolution rates were increased from 19%to 37%56%.The effect of electrostatic force in glutinous rice flour was promoted by protease treatment.There was greatest effect on protein dissolution rates for the middle layer,and the values were increased from 8%to 29%63%.Protein and starch were observed in the forms of bounding or dispersing in the upper layers of glutinous rice flours and this was not obvious in the middle layer.However,protein and starch was bound tightly in the lower layers of glutinous rice flours and large aggregates could be observed also.Based on the above researches,cyclone was used for separation the three layers of glutinous rice flour after hydrolyzed by protease A and the separation parameters were settled.In this study,CFD software?ICEM CFD and Fluent?was used to simulating the flow in cyclone and the combined values of operating parameters were optimized.It showed significant?p<0.01?for simulating the separation operation parameter models for the three layers of glutinous rice flours.Results of particle size distribution determination showed that the particle size distribution and densities of upper flow and down flow were suitable for cyclone separation.So,ideal separation efficiency could be achieved by controlling the separation parameters of hydrocyclone.Firstly,the effects of feed pressure on feed flow,feed rate,split ratio,and separation efficiency were studied.According to the ranges of actual equipment pressure,0.6MPa was chosen as suitable feed pressure for separation.Next,the effects of down flow pressure,up flow pressure,and feed concentration on feed flow and separation efficiency were studied.Results showed that the down flow separation efficiency decreased with increasing down flow pressure and decreasing up flow pressure.Down flow separation efficiency also decreased with increasing feed concentration.In order to obtaining the lower layer of glutinous rice flour,separation efficiency of 33%in the first grade was settled and the optimization separation parameters of up and down flow pressure were 0 MPa and 0.230.29 MPa,respectively.The up and down overflow of first grade separation were the second grade separation feed and the lower layer of glutinous rice flour,respectively.The protein content of the lower layer was about 4.25%at the present conditions.The optimization second grade separation parameters of up,down flow pressure,and feed concentration were 0.0550.12 MPa,0.100.16 MPa,and 15%respectively,for the settled separation efficiency of 50%.The up and down overflow of second grade separation was the third grade separation feed and the middle layer of glutinous rice flour,respectively.The protein content of the middle layer was about0.5%at the present conditions.The optimization separation parameters of up and down flow pressure were 0.250.32 MPa and 0 MPa,respectively,for the settled separation efficiency of80%.The up overflow of third grade separation was refined and dried for producing rice protein peptide product.The down overflow of third grade separation was the upper layer of glutinous rice flour and the protein content was about 8.7%.Finally,the application characteristics of three kind of glutinous rice deep processing products were studied.Effects of protein content on property changes of glutinous dumplings made by glutinous rice flours with proteases treatment were studied.Binding ability of chemical components to hydrogen protons in glutinous rice flour were affected by protein content.With increasing in protein content,the solubility and transparency of glutinous rice flours decreased significantly.When protein content increased from 2%to 6%,the solubility at 50°C and 95°C decreased by 30%55%and 6%15%respectively,and the transparency of glutinous rice flour decreased by 8%18%.Pasting properties showed that peak viscosity decreased significantly and the largest change in the peak viscosity after protease C treatment was observed with increasing protein content,which decreased by 21%.Results showed that the glutinous dumplings made by glutinous rice flours with proteases treatment were brighter and less yellow,and TPA values of hardness,springiness,resilience,and gumminess were decreased.Determination of stress relax showed that stress resistance from the processing operation was lower.This means energy saving during glutinous rice product processing.Sensory evaluation results showed that the glutinous dumplings with 4%5%protein content gained highest scores because of bright and delicate gloss appearance,smooth mouth feeling,and easy to chew.Glutinous rice starch product was an ideal additive for high-grade ice cream and cosmetics.The300700 Da molecular weight was up to 65%66%proportion in protein peptide product and showed potential antioxidant activity and ACE inhibitory activity according to the amino acid composition. |
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