棉籽蛋白的研究进展

我国棉花产量丰富,棉籽仁提油后的棉籽饼粕中,蛋白质含量高达60%。棉籽蛋白是一种营养价值高、品质优良的植物蛋白,在食品行业有着广泛的应用。介绍了棉籽蛋白的提取和水解的方法,阐述了各种方法的优缺点,并综述了其最新研究进展。     

不同蛋白酶对天龙粉水解作用的比较研究

目的以天龙粉为原料,用五种蛋白酶分别进行酶解,以蛋白质的水解度为指标,评价不同酶对天龙粉的水解效果。方法天龙粉分别经过胰蛋白酶、胃蛋白酶、胰凝乳蛋白酶、弹性蛋白酶和木瓜蛋白酶酶解得到酶解液,采用茚三酮比色法测定蛋白质的水解度。结果胃蛋白酶和弹性蛋白酶的水解度较高,分别为73.18%、76.33%,木瓜蛋白酶的水解度为57.34%,胰蛋白酶和胰凝乳蛋白酶的水解度较低,分别为29.68%、34.05%。结论不同酶酶解天龙粉,弹性蛋白酶的酶解作用最强,其次是胃蛋白酶、木瓜蛋白酶、胰凝乳蛋白酶,胰蛋白酶水解作用最弱。     

木瓜蛋白酶水解明胶制备多肽的工艺研究

以明胶为原料,用木瓜蛋白酶降解制备多肽。试验中用甲醛滴定法和三氯醋酸法(TCA)测定明胶水解度,并将两种方法进行比较。得出甲醛滴定法简单易行便于过程控制,适合于工业生产需要。并系统的研究了pH、温度、酶量、底物浓度、以及反应时间等因素对明胶降解的影响,确定了制备护发调理剂最佳的水解工艺条件:底物浓度5%(w/v)明胶溶液,pH=7.0,木瓜蛋白酶量0.20%～0.30%,反应温度60℃,反应时间60 min。     

碱性蛋白酶水解林蛙卵粕蛋白的工艺条件优化

研究了碱性蛋白酶水解林蛙卵粕蛋白制备混合氨基酸的工艺,分析了反应温度、酶加量、底物浓度和反应时间对蛋白水解度的影响.通过单因素实验和正交实验确定碱性蛋白酶水解林蛙卵粕蛋白的最佳工艺条件为:反应温度60℃、酶加量2000 U·g-1、底物浓度4％、反应时间120min,此时的蛋白水解度为10.18％.     

白乳胶中甲醛含量测定方法研究

采用化学滴定法(碘量法)和乙酰丙酮分光光度法对五种市售白乳胶中甲醛含量进行测定与比较,并设计出一种可以快速简便测定甲醛含量的定性方法——希夫试剂比色法。结果表明:采用碘量法和分光光度法测定白乳胶中游离甲醛含量,两者测试结果相近,偏差在2.6%～7.0%之间;希夫试剂比色法操作简单、快速,但误差较大,可以用作快速定性判定样品中是否含有游离甲醛;在其它条件保持不变的前提下,测试温度越高,白乳胶中游离甲醛含量的测试结果越大。     

水萃取法测定纺织品甲醛含量不确定度的评定

文章评定了GB 18401-2010《国家纺织产品基本安全技术规范》中三类纺织品服装的游离甲醛限量的相对不确定度和扩展不确定度。建立纺织品甲醛含量不确定度的数学模型,系统分析计算不确定度的各个分量[1]。按GB/T 2912.1-2009《纺织品甲醛的测定第1部分:游离和水解甲醛(水萃取法)》测定了三类纺织品中的甲醛含量,其扩展不确定度分别为2.0 mg/kg、4.0 mg/kg、13.0 mg/kg。当样品甲醛的含量在限量附近时,用不确定度校正后的结果更可靠和准确。     

蚕丝蛋白水解工艺及作为化妆品添加剂的应用研究

蚕丝蛋白是一种新型化妆品添加剂,含有多种氨基酸和蛋白质,无毒、副作用,具有很广泛的应用价值。研究了蚕丝水解液的制备工艺及水解过程中pH、温度、反应时间对水解程度的影响。结果表明,pH越高,蚕丝蛋白水解程度越大,收率越高。较高的温度可使蚕丝蛋白水解速度加快,但水解液颜色较深,较低的温度,水解速度较慢。反应时间越长,蚕丝蛋白水解程度越大。并介绍蚕丝水解液在化妆品中的添加方法及如何解决试验过程中存在的实际问题。     

明胶水解程度测定方法的探讨

本文探讨了FDNB、紫外分光光度法、甲醛反应滴定法、粘度法测定明胶水解程度的可能性,并对他们作了一定的研究。实验结果表明,紫外分光光度法、甲醛反应滴定法简便易行,有可能在水解明胶的工业生产中获得应用,但关键是要采用一个合适的测试液浓度和合适的滴定用的碱液浓度,才能确切地反应出明胶水解的规律,从而可以测得明胶的水解程度。     

无机富锌底漆固化剂影响因素的研究

溶剂型无机富锌底漆以正硅酸乙酯的水解液为固化剂。研究了正硅酸乙酯水解的各种因素,如水解度、催化剂、水解介质、水解温度、催化剂滴加速度等对水解液性能的影响。     

热碱法脱除游离棉酚的实验研究

介绍了用热碱法对棉籽粕进行脱酚的工艺原理,并对棉籽粕进行了脱酚实验研究。通过正交试验,热碱法脱酚的最适合条件为pH值8～9,温度60℃,时间3h,最终棉籽蛋白液棉酚含量为12×10-6,完全低于联合国咨询委员会规定的食用棉籽蛋白质中游离棉酚含量≤0.06%标准。     

棉籽蛋白质塑料改性研究

以棉籽粕为原料,盐提酸沉的方法来制备棉籽蛋白质,将提取出的棉籽蛋白质与不同比例的马来酸酐和一定量甘油混合,经模压成型制得棉籽蛋白质塑料,并对其进行力学性能测试、吸水性测试、溶解性的测试和红外光谱分析。考察了加工条件对蛋白质塑料性能的影响,结果表明：马来酸酐的加入提高了蛋白质材料的断裂伸长率,同时显著降低了材料的吸水率。通过对加工条件的考察,得到了热压棉籽蛋白质塑料的最佳工艺条件：140℃,10 MPa下模压10 min。     

Wood adhesive properties of cottonseed protein with denaturant additives

Most commercial wood adhesive use either formaldehyde-based resins or polyurethanes, both of which include potentially toxic chemicals in their formulations. As a result, proteins are being considered as greener and more sustainable wood adhesives. While most of the protein adhesive studies focus on soy proteins, there is also interest in exploring alternatives. In this work, testing of the adhesive performance of cottonseed protein isolate was undertaken in the presence of protein denaturants, i.e. guanidine hydrochloride (GuHCl), sodium dodecyl sulfonate (SDS), urea, and alkali. For comparison, soy protein isolate was also included in the study. At optimal dosage levels, the dry adhesive strength of cottonseed protein isolate could be enhanced by 38, 25, or 47% with SDS, GuHCl, or urea, respectively. The dry adhesive strength and hot water resistance of cottonseed protein isolate was generally superior to that of soy protein isolate, with or without the denaturants. Thus, the combination of cottonseed protein with an optimal concentration of a denaturant may be a potentially promising polymeric system for use as wood adhesives.     

A new method of detoxification of cottonseed by means of mixed solvent extraction

For several decades, scientists in the field of vegetable oils tried unsuccessfully to detoxify cottonseed by a practical method. By using 20-30% (by wt) of ethyl alcohol (90% in vol) with commercial hexane as a mixed solvent, we were able to extract effectively both gossypol and oil from cottonseed prepressed cake or flakes. Free gossypol in meal was reduced to ca. 0.013-0.04%; total gossypol was reduced to 0.32-0.55%; residual oil was reduced to ca. 0.5% or less. Any aflatoxin present also can be eliminated by this process. The detoxified cottonseed meal can be used as animal feed. Cottonseed protein can be used to substitute for soy protein. The extracted oil is of better quality than that obtained by the usual hexane extraction method, and gossypol is a valuable byproduct.     

Use of additives to enhance the properties of cottonseed protein as wood adhesives

Soy protein is currently being used commercially as a “green” wood adhesive. Previous work in this laboratory has shown that cottonseed protein isolate, tested on maple wood veneer, produced higher adhesive strength and hot water resistance relative to soy protein. In the present study, cottonseed protein and soy protein isolates were tested on different wood types, and cottonseed protein again showed better performance relative to soy protein. Furthermore, the effects of several protein modifiers were evaluated, including amino acids, fatty acids, and other organic molecules with cationic or anionic charges. Aspartic acid, glutamic acid, acetic acid, butyric acid, and adipic acid gave improved performance when included with cottonseed protein isolate whereas no significant effect was observed on soy protein isolate. Both dry adhesive strength and hot water resistance were tested. The enhanced performance observed with these additives provides an additional incentive for the use of cottonseed protein in this application.     

Cottonseed protein-based wood adhesive reinforced with nanocellulose

Although protein-based adhesives are eco-friendly, sustainable, and biodegradable, continued improvement in their adhesive performance is desirable. In this work, the effect of adding nanocellulose particles to cottonseed protein-based wood adhesives was studied. Cellulose nanofibers (CNF) were found to be most beneficial at about a 2% additive level, giving 22% improvement in dry adhesive strength over the cottonseed protein control. Cellulose nanocrystals (CNC) were optimal at about 10% additive level, giving 16% strength improvement relative to cottonseed protein alone. The hot water resistance of cottonseed protein isolate was also improved with CNF addition, but not with CNC addition. For comparison, soy protein isolate was also studied and showed about the same relative dry strength improvements with nanocellulose addition, but improvement of hot water resistance was less apparent. Infrared and thermogravimetric analysis suggested that the protein and the nanocellulose were interacting with each other. Thus, CNF may be a useful additive to cottonseed protein formulations used as wood adhesives.     

Influence of dietary fat and protein on serum cholesterol of cholesterol-fed chicks

Summary Cottonseed oil, partially hydrogenated cottonseed oil and corn oil, were fed at 4% and 10% of the diets with two levels of protein, 19% and 25%, and with 0.5% cholesterol to cockerels 21 days of age for a period of 38 days. Blood samples were obtained at 0, 14, 24, and 38 daysvia heart puncture. The data indicate that the serum cholesterol value, irrespective of the level or type of fat, was significantly lower in those groups of birds which were fed the higher level of protein. Excluding the combination of 19% protein and 10% cottonseed oil, the degree of saturation did not have any apparent effect upon serum cholesterol because the mean differences among the oils and between the fat levels were not statistically significant.     

改性棉籽蛋白对天然橡胶复合材料性能的影响

将间苯二酚-甲醛改性棉籽蛋白等量代替炭黑填充天然橡胶(NR),利用红外光谱对棉籽蛋白和改性棉籽蛋白进行对比分析,研究了棉籽蛋白用量对橡胶复合材料静态力学性能、热空气老化性能及生热和剪切动态性能的影响。结果表明,棉籽蛋白中的氨基被取代;改性蛋白质低于9份时NR的综合力学强度增加,回弹性提高,抗老化性能提高;改性蛋白质使橡胶复合材料的生热性能降低,储能模量升高,损耗因子降低。     

Isopropanol as a solvent for extraction of cottonseed oil

Phase equilibrium data for the system; cottonseed oil-isopropanol-water were determined at 30°C. and compared with data for the system; cottonseed oilethanol-water. The relative phase distribution of fatty acids and cottonseed oil in mixtures with isopropanol and water was studied under varying conditions of water and fatty acid concentrations. These tests showed the fatty acids to be highly concentrated in the alcohol-water phase. Flaked cottonseed meats were extracted in continuous extraction apparatus with 91% isopropanol, 99% isopropanol, and mixtures of commercial hexane and isopropanol. Analytical data on the extractions show that 91% isopropanol is an efficient solvent for extracting active gossypol along with the oil. Rat and swine feeding tests of the isopropanol extracted meal showed it to be highly superior to hydraulic meal as a source of protein. A method was developed for treatment of the cottonseed-isopropanol miscella by liquid-liquid extraction to separate purified oil and fatty acid fractions from other materials in the extract.     

Effects of phosphorus-containing additives on soy and cottonseed protein as wood adhesives

Soy and cottonseed proteins appear promising as sustainable and environment-friendly wood adhesives. Because of their higher cost relative to formaldehyde-based adhesives, improvement in the adhesive performance of proteins is needed. In this work, we evaluated the adhesive properties of soy and cottonseed protein formulations that included phosphorus-containing acids and esters. For cottonseed protein isolate, most of these additives improved dry adhesive strength, with methylphosphonic acid, phosphorous acid, and phosphoric acid increasing the dry strength by 47, 44, and 42%, respectively, at their optimal concentrations. For soy protein isolate, these additives did not show significant benefits. The phosphorus-containing additives also improved the hot water resistance of the cottonseed protein formulations but showed either no effect or a negative effect for the of soy protein formulations. Thus, the combination of cottonseed protein with phosphorus additives appears to be attractive as wood adhesives.