农业工程学报
農業工程學報
농업공정학보
2014年
19期
332-338
,共7页
杨敏%张克平%王江鱼%杨继涛%杨晰
楊敏%張剋平%王江魚%楊繼濤%楊晰
양민%장극평%왕강어%양계도%양석
神经网络%蛋白质%pH%牦牛乳酪蛋白%琥珀酰化%乳化性%疏水性%广义回归神经网络预测
神經網絡%蛋白質%pH%牦牛乳酪蛋白%琥珀酰化%乳化性%疏水性%廣義迴歸神經網絡預測
신경망락%단백질%pH%모우유락단백%호박선화%유화성%소수성%엄의회귀신경망락예측
neural network%protein%pH%yak casein%succinylation%emulsification%hydrophobicity%generalized regression neural network
为了研究琥珀酰化修饰后酪蛋白乳化性与疏水性关系，该文以琥珀酰化牦牛乳酪蛋白为研究对象，分析了不同酰化程度酪蛋白乳化性及疏水性变化趋势，采用广义回归神经网络建立了牦牛乳酰化酪蛋白乳化性与疏水性关系模型。结果显示，琥珀酰化牦牛乳酪蛋白乳化性和疏水性均与酰化程度、pH值有关，pH值为5以上，随着酰化程度的增加，酪蛋白乳化活性增大；等电点附近，酪蛋白乳化活性较差，等电点之后乳化活性迅速增大。pH值介于2-6时，所有酪蛋白乳化稳定性较强，pH值介于6-11之间时，酪蛋白乳化稳定性差异较小，pH值为12时乳化稳定性有所增加。酪蛋白内荧光与1-苯胺基萘-8-磺酸（1-aniline napthalene-8-sulfonic acid, ANS）外源荧光最大荧光强度和最大发射波长随酰化程度及 pH 值变化表现出较为复杂的关系。通过广义回归神经网络（generalized-regression-neu-network，GRNN）建立了牦牛乳酪蛋白疏水性参数、pH值、酰化程度与乳化性关系，网络模型对乳化性的预测相对误差小于10%，预测结果良好。研究结果为酪蛋白乳化性研究提供了参考依据。
為瞭研究琥珀酰化脩飾後酪蛋白乳化性與疏水性關繫，該文以琥珀酰化牦牛乳酪蛋白為研究對象，分析瞭不同酰化程度酪蛋白乳化性及疏水性變化趨勢，採用廣義迴歸神經網絡建立瞭牦牛乳酰化酪蛋白乳化性與疏水性關繫模型。結果顯示，琥珀酰化牦牛乳酪蛋白乳化性和疏水性均與酰化程度、pH值有關，pH值為5以上，隨著酰化程度的增加，酪蛋白乳化活性增大；等電點附近，酪蛋白乳化活性較差，等電點之後乳化活性迅速增大。pH值介于2-6時，所有酪蛋白乳化穩定性較彊，pH值介于6-11之間時，酪蛋白乳化穩定性差異較小，pH值為12時乳化穩定性有所增加。酪蛋白內熒光與1-苯胺基萘-8-磺痠（1-aniline napthalene-8-sulfonic acid, ANS）外源熒光最大熒光彊度和最大髮射波長隨酰化程度及 pH 值變化錶現齣較為複雜的關繫。通過廣義迴歸神經網絡（generalized-regression-neu-network，GRNN）建立瞭牦牛乳酪蛋白疏水性參數、pH值、酰化程度與乳化性關繫，網絡模型對乳化性的預測相對誤差小于10%，預測結果良好。研究結果為酪蛋白乳化性研究提供瞭參攷依據。
위료연구호박선화수식후락단백유화성여소수성관계，해문이호박선화모우유락단백위연구대상，분석료불동선화정도락단백유화성급소수성변화추세，채용엄의회귀신경망락건립료모우유선화락단백유화성여소수성관계모형。결과현시，호박선화모우유락단백유화성화소수성균여선화정도、pH치유관，pH치위5이상，수착선화정도적증가，락단백유화활성증대；등전점부근，락단백유화활성교차，등전점지후유화활성신속증대。pH치개우2-6시，소유락단백유화은정성교강，pH치개우6-11지간시，락단백유화은정성차이교소，pH치위12시유화은정성유소증가。락단백내형광여1-분알기내-8-광산（1-aniline napthalene-8-sulfonic acid, ANS）외원형광최대형광강도화최대발사파장수선화정도급 pH 치변화표현출교위복잡적관계。통과엄의회귀신경망락（generalized-regression-neu-network，GRNN）건립료모우유락단백소수성삼수、pH치、선화정도여유화성관계，망락모형대유화성적예측상대오차소우10%，예측결과량호。연구결과위락단백유화성연구제공료삼고의거。
Yaks (Bos grunniens) from the Qinghai-Tibetan plateau are the sole source of milk of local inhabitants. In the past years, yak milk has attracted more and more attention, due to its increasing demand. Yak milk is widely used to produce butter, soft and hard cheeses, yogurt, milk powder, Qula, and casein-containing products. Caseins, the major protein in milk, are commonly used in the food, chemical, cosmetic, and pharmaceutical industries. Yak caseins are widely used to produce high quality food ingredients and soaps, glues, leather polishing reagents, and clothing, among others. However, compared to cow caseins, yak caseins have poor solubility, which affects the other functional properties. The poor solubility of yak caseins is mostly attributed to its conformation. Succinylation is the most frequently used modification method, which changes the conformation and increases the net charge of protein, which improves its functional properties consequently. It was indicated that the reaction conditions were mild and easy to control, the modified level was higher than other chemical modification, and its modification effect was outstanding. <br> In this study, yak milk caseins were selected as materials and succinylation was used to modify the yak casein, and the effect of succinylation on casein emulsification and hydrophobility was studied. The GRNN was also used to build the model of relationship between pH, succinylated level, the main parameters of caseins hydrophobility, emulsifying properties, and it was proved to have good predictability. <br> The results showed that the emulsifying properties of protein were affected by pH, spacial conformation, and hydrophobility mainly, and they were non-linearly related. The emulsification and hydrophobility of yak caseins were influenced by the degree of succinylation and pH. Above a pH of 5, with the increase of degree of succinylation, emulsifying activity of caseins increased. Near the isoelectric point, emulsifying activity was poorer, and then increased rapidly with the increasing of pH. The emulsion stability of modified casein was stronger with pH between 2-6, which changed slowly with pH between 6-11, and then increased greatly with pH at 12, and the emulsion stability of 10 min increased obviously. The values of native and ANS fluorescence intensity and maximum emission wavelength of native and ANS fluorescence of modified casein showed a more complex relationship with succinylated degree and the pH. GRNN had a good performance in deal with complex relationships of non-linear, which was used to establish the relationship model between succinlated level, pH, vital parameters of hydrophobility, and emulsifying properties in order to predict the emulsifying activity and emulsion stability with 10 min and 30 min. The error of predicted values was within 10%, so the results of prediction were credible. The model would save time and the cost of test about studying and predicting yak caseins emulsifying properties. The results could provide references for the study on emulsification of yak caseins and succinylation caseins.
