| Cotten seed kernel meal is the by-product of cottonseed after unshelling and oil extraction.There is high content of protein in the Cotten seed kernel meal.Thus,cottonseed protein could be a cheap protein source as a solution for protein lacking in food industry and breeding industry because of its high yield and developmental nutrition.Howver the poor functional properties limited the widly application in food industry.Thus,the cottonseed protein requires modified to improve its functional porperties.In this study,the effect of ultrasound treatment and radio frequence treatment on structure properties and functional properties of cottonseed protein was researched.The main findings are as follows:1.The range of protein cotant of cotten seed kernel flour is 25.79%to 43.77%,The protein cotant of market cotten seed kernel flour is significantly higher than any other cotten seed kernel flour.After oil extraction processing(n-hexane),the The cotten seed kernel meal was obtained.The functional properties of market cotten seed kernel meal is also significantly higher than any other cotten seed kernel meal.At natural p H condition.,the EAI,ES FC,FS,WAC and OAC of market cotten seed kernel meal is 12.53 m~2/g,15.96min,20.64%,27.65%,2.83 g/g and 1.65 g/g,respectively.The Pima90-53(No.95 sample)showed the lowest protein content which lead to the worst functional properties in all samples.The solubility of cotten seed kernel meal increased before decreased when p H value rise from 1.0 to 10.0.The lowest solubility was found at p H 3.0.2.The ultrasound treatment could transform the structure properties and functional properties of cottonseed protein.The ultrasound treatment decreased the paricle size of cottonseed protein form 2404.3 nm to 902.5 nm which increase the specific surface area.The ultrasound treatment increased the content of free sulfydryl and the surface hydrophobicity.The result indicated that the sulfydryl group and hydrophobic group is exposed and the protein is unfolded.The secondary structure is changed at the same time.The stableβ-sheet transform toβ-turn.To be specific,β-sheet decreased from 34.50%to 28.90%while theβ-turn increased from 22.03%to 33.30%.Thus,the heat stability of cottonseed protein was reduced.The denaturation temperature decreased from 97.23℃to 92.43℃,and the enthalpy change decreased form 4.95 J/g to 2.09 J/g.The functional properties of cottonseed protein were imporved significantly.When the modified condition set as 600W30min,the EAI,ES FC,FS,and OAC was 21.17 m~2/g,25.06min,83.79%,71.17%and 4.78 g/g,respectively.However,the functional properties were reduced when the ultrasound treatment power rise to 800W.Highly surface hydrophobicity result to aggregation which increase the content of insoluble protein.3.The radio frequency treatment could transform the structure properties and functional properties of cottonseed protein.The radio frequency treatment decreased the paricle size of cottonseed protein form 2404.3 nm to the 895.3 nm.The radio frequency treatment changed the content of free sulfydryl and the surface hydrophobicity from 15.03μmol/g and 535 to34.11μmol/g and 1090.0,respectively.The result indicated that the sulfydryl group and hydrophobic group is exposed and the protein is unfolded.The secondary structure is changed too.The stableβ-sheet transform toβ-turn.To be specific,β-sheet decreased from34.50%to 28.36%,the random coil was decreased from 24.10%to 12.30%,theβ-turn increased from 22.03%to 41.92%.Thus,the heat stability of cottonseed protein was reduced.The denaturation temperature decreased from 97.23℃to 94.32℃,and the enthalpy change decreased form 4.95 J/g to 3.75 J/g.When the modified condition set as 145mm and 90℃,the EAI,ES FC,FS,WAC and OAC of protein was 66.29%,19.61 m~2/g,22.12 min,98.85%,96.12%,5.55 g/g,3.34 g/g,respectively。... |
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