Comparison of structural and physicochemical properties of potato protein and potato flour modified with tyrosinase

The present study modified potato protein and flour with tyrosinase to promote the diversification of potato staple foods.The results indicated that tyrosinase treatment markedly altered the secondary structure of proteins.After tyrosinase treatment,the maximum decomposition temperature of potato protein and flour increased from 322.32 to 332.40℃ and from 294.24 to 299.61℃,respectively.Tyrosinase treatment remarkably reduced the pasting viscosity of potato flour,that is,the peak viscosity,through reducing viscosity,breakdown,final viscosity,and setback by 32.50,60.98,13.04,68.24,and 74.31%,respectively.In contrast,tyrosinase treatment increased the shear resistance and hardness of the protein and flour gels;the maximum stress values of the protein and flour gels increased from 1.48 to 10.1% and from 6.87 to 14.8%,respectively.Furthermore,tyrosinase treatment promoted viscoelastic properties and structural stability of potato protein and flour.These results may provide an important foundation for the development of novel potato staple foods.

Anticancer effects of sweet potato protein on human colorectal cancer cells

AIM: To investigate the effects of proteins purified from sweet potato storage roots on human colorectal cancer cell lines. METHODS: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Hoechst 33258 nuclear staining and Boyden transwell chamber methods were used to determine whether purified sweet potato protein (SPP) from fresh sweet potato roots affected proliferation, migration and invasion, respectively, of human colorectal cancer SW480 cells in vitro . The inhibitory effects of SPP on growth of human colorectal cancer HCT-8 cells intraperitoneally xenografted in nude mice and spontaneous lung metastasis of murine Lewis lung carcinoma 3LL cells subcutaneously transplanted in C57 BL/6 mice were also investigated in vivo . RESULTS: SPP inhibited the proliferation of SW480 cells in a dose-dependent manner, with an IC 50 value of 38.732 μmol/L (r2 = 0.980, P = 0.003) in the MTT assay. Hoechst 33258 nuclear staining further revealed inhibition of cell viability and induction of apoptosis by SPP. The transwell assay disclosed significant reduction in migrated cells/field by 8 μmol/L SPP (8.4 ± 2.6 vs 23.3 ± 5.4, P = 0.031) and invaded cells/field through the ECMatrix by 0.8 μmol/L SPP, compared with the control (25.2 ± 5.2 vs 34.8 ± 6.1, P = 0.038). Both intraperitoneal (ip) and intragastric (ig) administration of SPP led to significant suppression of growth of intraperitoneally inoculated HCT-8 cells in nude mice to 58.0% ± 5.9% (P = 0.037) and 43.5% ± 7.1% (P = 0.004) of the controls, respectively, after 9 d treatment. Bloody ascites additionally disappeared after ip injection of trypsin inhibitor. Notably, ig and ip administration of SPP induced a significant decrease in spontaneous pulmonary metastatic nodule formation in C57 BL/6 mice (21.0 ± 12.3 and 27.3 ± 12.7 nodules/lung vs 42.5 ± 4.5 nodules/lung in controls, respectively, P < 0.05) after 25 d treatment. Moreover, the average weight of primary tumor nodules in the hind leg of mice decreased from 8.2 ± 1.3 g/mice in the control to 6.1 ± 1.4 g/mice in the ip group (P = 0.035). CONCLUSION: SPP exerts significant antiproliferative and antimetastatic effects on human colorectal cancer cell lines, both in vitro and in vivo .

Relationship Between Soluble Protein,Chlorophyll and ATP in Drought-Resistant Sweet Potato Under Water Stress

Some indices concerning the metabolism of substance and energy in sweet potato leaves under water stress were studied. The results showed an obvious increase in soluble protein content. Compared with control, Chl a, Chl b, total Chl contents and the ratio of Chl a to Chl b all decreased to some extent. ATP content increased in some varieties and decreased in others, but the stronger the drought resistance of the variety , the higher the ATP content. The correlation coefficient(r)of the soluble protein content, ratio of Chl a to Chl b and ATP content as a percentage of the drought-resistant sweet potato control variety are 0. 8968, - 0. 8509 and 0. 8200, respectively, P<0. 01. So these indices can be used to evaluate the drought resistance of different sweet potato varieties.

Nutritional and Functional Characteristics of Protein-Fortified Pasta from Sweet Potato

Despite being a healthy low glycaemic index food, the production and consumption of sweet potatoes are decreasing globally. The global production trends indicated a decline from 130.47 million tonnes (MT) in 2004 to 107.64 MT in 2009, while the production in China, having the largest share towards world production of sweet potatoes, witnessed a decrease from 105.84 MT in 2004 to 81.21 MT in 2009. There is an interest in increasing consumption of healthy low glycaeimic index foods, especially in the context of a projected alarming rise in the diabetic population in the developing world by 2025. The objective of this study was to enhance the utilization of sweet potato as a low glycaemic food, mainly through its use in the development of high protein pasta. Among three protein sources, whey protein concentrate (WPC), defatted soy flour (DSF), and fish powder (FP), WPC gave high quality pasta with strong starch-protein network formation, as evidenced from scanning electron microscopic studies and low in vitro starch digestibility. Protein nutritional quality was also high for WPC-fortified sweet potato pasta, with very high scores for lysine and leucine as well as high essential amino acid index and calculated protein efficiency ratio. Fractionation of starch showed that the WPC-fortified sweet potato pasta had the lowest rapidly digested starch (RDS) and the highest resistant starch (RS) content, indicating its potential as a low glycaemic food.

Enzyme Aided Low Temperature Evaporation for Concentration of Active Proteins from Potato Fruit Juice

Extraction of starch from potato leads to formation of potato fruit juice (PFJ), which consists of proteins, fibers, starch and water. PFJ contains 1% - 3% [w/w] of proteins, including protease inhibitors that are potentially valuable for various applications, and could thus bring added value to the potato industry. The use of proteins of PFJ in bioactive form is limited by lack of benign and cost-efficient concentration technologies. The present approach combines a previously introduced low-temperature mechanical vapor compression evaporation technology with option to enzymatic viscosity management in case of high-viscosity fluids. In pilot-scale evaporation, an increase of solid content from 10% to 40% was achieved without major technical challenges. The proposed method offers a low-energy means for the concentration potato industry wastewater and reclamation of valuable proteins in active form.

Protein and Phenolic Contents and Antioxidant Activities of 14 Early Maturing Potatoes as Affected by Processing

The effects of processing and genotype (fourteen early potato varieties) were evaluated for their phytochemicals, total phenolics (TPC), total flavonoids (TFC), total anthocyanins (TAC), antioxidant activities measured by ORAC, FRAP and DPPH assays and protein content. While all these profiles were highly dependent on the potato variety and processing, F09085, F10090, French Fingerlings, Purple Fiesta, Red Thumb, Ciklamen and Norland were identified as nutritionally rich in phytochemicals such as TPC, TFC, TAC, higher antioxidant capacities and protein (p p p < 0.0001).

The Key Factors Affecting Tuber Development of Potato in vitro and the Relation with Protein Fractions

According to previous analysis, some properties bounding up with tuber yield were investigated. The results showed that tuber average weight, plastid Mg2 + -ATPase activity, plastid Ca2 + -ATPase activity, mitochondria Mg2 + -ATPase activity, total soluble protein content, tuber average diameter, and Q-enzyme activity were important factors determining the tuber yield. The linear regression equation was:Y = 0.5211 + 0.0595X(1)+0.8389X(2) +0.0882X(3) -0.0073X(4) +0.1449X(5) +0.3510X(6) +0.0031X(7) -0.00003X(8) + 0.3412X(9) + 0.0127X(10) + 0.2904X(ll) + 0.0570X(12) + 0.0159X(13) + 0.3585X(14) + 0.0134X(15) - 0.1012X(16). At the same time, the relation between several important properties and soluble protein fractions were analyzed.

Sweet Potato Leaf Curl Virus: Coat Protein Gene Expression in <i>Escherichia coli</i>and Product Identification by Mass Spectrometry

Sweet potato is one of the first natural GMOs, genetically modified 8000 years ago by Agrobacterium rhizogenes as reported recently by Kyndt et al. A section of 10 kbp long DNA (Transferred- DNA or T-DNA) of the Ri (Root-inducing) plasmid was transferred to the plant genome by A. rhizo-genes and has been maintained in all 291 hexaploid sweet potato cultivars of the world. The maintenance in the sweet potato genome and expression of two T-DNA genes for tryptophan-2-monooxygenease (iaaM) and for indole-3-acetamide hydrolase (iaaH) are likely to be physiologically significant since these enzymes convert tryptophan to indole-3-acetic acid, a major plant growth hormone auxin. Sweet potato (Ipomoea batatas (L.) Lam) is ranked the third most important root crop after potato and cassava, and the seventh in global food crop production with more than 126 million metric tons. Although sweet potato originated in Central or South America, China currently produces over 86% of world production with 109 million metric tons. In the United States, North Carolina is the leading producer with 38.5% of the 2007 sweet potato production, followed by California, Mississippi, and Louisiana with 23%, 19%, and 15.9%, respectively. Leaf curl virus diseases have been reported in sweet potato throughout the world. One of the causal agents is Sweet potato leaf curl virus (SPLCV) belonging to the genus Begomovirus (family Geminiviridae). Although SPLCV does not cause symptoms on Beauregard, one of the most predominant sweet potato cultivars in the US, it can reduce the yield up to 26%. Serological detection of SPLCV is not currently available due to the difficulties in obtaining purified virions that can be used as antigen for antiserum production. In attempts to obtain the coat protein (CP) of SPLCV for antibody production, primers were designed to amplify the CP gene. This gene was cloned into the expression vector pMAL-c2E as a fusion protein with maltose-binding protein, and transformed into Escherichia coli strain XL1-Blue. After gene induction, a fusion protein of 72 kDa was purified by amylose affinity chromatography. The yield of the purified fusion protein was approximately 200 μg/liter of bacterial culture. Digestion with enterokinase cleaved the fusion protein into a 42.5 kDa maltosebinding protein and a 29.4 kDa protein. The latter protein was identified by mass spectrometry analysis as the coat protein of SPLCV based on the fact that the mass spectrometry elucidated the sequences corresponding to 37% of amino acid positions of the SPLCV coat protein.

不同富硒方式对甘薯叶蛋白抗氧化活性的影响

以甘薯叶为研究对象,分别对叶面与土壤进行富硒处理,通过分析甘薯叶中硒含量及甘薯叶蛋白的抗氧化活性的变化,研究不同富硒方式对甘薯叶蛋白抗氧化活性的影响。结果显示叶面富硒与土壤富硒都能提高甘薯叶蛋白的硒含量,在1.6 mg/mL的富硒质量浓度条件下两种富硒处理组蛋白硒含量分别达到了20.10 mg/g与1.68 mg/g。富硒对甘薯叶蛋白的抗氧化活性有一定的提升作用,其中,叶面富硒可使甘薯叶蛋白超氧阴离子自由基清除率提升19.17%。根据相关性分析可知,除硒含量对抗氧化活性有较大影响外,样品中总酚与总黄酮含量也在一定程度上影响着样品的抗氧化活性。经对比可知,叶面富硒能更好地提高甘薯叶蛋白中的硒含量,是较佳的富硒方式。

马铃薯蛋白饲料对断奶仔猪生长性能、免疫器官指数及抗氧化功能的影响

文章旨在探究马铃薯蛋白饲料对断奶仔猪生长性能、免疫器官指数及抗氧化功能的影响。试验将400头28日龄体重(7.93±0.14)kg的健康杂交仔猪随机分为4组,每个重复10头,各组分别饲喂添加0%、1%、2%和4%的马铃薯蛋白饲料的试验日粮。试验为期28d。结果表明:与对照组相比,补充2%和4%马铃薯蛋白组仔猪的平均日增重(ADG)分别显著降低9.87%和10.19%(P<0.05);补充2%和4%马铃薯蛋白组仔猪的F/G分别显著提高11.20%和11.11%(P<0.05);此外,补充0%~4%的马铃薯蛋白对仔猪初重(IBW)、末重(FBW)和平均日采食量(ADFI)均无显著影响(P>0.05)。补充2%和4%马铃薯蛋白组仔猪的淋巴结指数和胰腺指数显著低于对照组(P<0.05);与对照组相比,补充0%~4%的马铃薯蛋白组仔猪的脾脏指数显著提高(P<0.05);此外,补充0%~4%的马铃薯蛋白对仔猪肝脏、肾脂、腹股沟淋巴结和胸腺指数均无显著影响(P>0.05)。补充2%和4%马铃薯蛋白组仔猪血清SOD活性显著提高,且组间差异不显著(P>0.05);补充0%~4%马铃薯蛋白组仔猪血清OH显著降低(P<0.05);与对照组相比,补充2%~4%马铃薯蛋白组仔猪血清H_(2)O_(2)显著提高(P<0.05);此外,补充0%~4%马铃薯蛋白对仔猪血清过氧化氢酶(CAT)活性、总抗氧化能力(T-AOC)能力和一氧化氮(NO)含量均无显著影响(P>0.05)。总之,马铃薯蛋白添加量高于2%时,对仔猪生长性能有明显负面影响。因此,在本试验条件下,马铃薯蛋白最适添加量为1%。

不同提取方法提取马铃薯蛋白的研究

该实验以新鲜马铃薯为原料,采用醇溶法、盐溶法、碱溶法3种方法提取马铃薯蛋白,测定其纯度和提取率,结果表明,醇溶法提取的马铃薯蛋白纯度为94.5%,提取率为4.5%,提取效果最好。通过SDS-PAGE电泳分析,醇溶法提取的马铃薯蛋白亚基条带多,分子量范围广,并且在分子量为25~40 kDa范围内含量很高,说明醇溶法能有效提取马铃薯蛋白质的各个组分;进一步研究其理化性质,发现醇溶法提取的蛋白质持油性、持水性、乳化性、乳化稳定性更好;水解度分析显示醇溶法提取的马铃薯蛋白水解度更高。因此,在这3种方法中,醇溶法是比较经济、所得蛋白质性质较好的提取方法。

马铃薯蛋白-黄原胶复合物对荞麦面团发酵特性的影响

研究在不同pH条件下(2.67、4.69、7.48)制备的马铃薯蛋白-黄原胶复合物(PP-XGC)的疏水性、乳化性和起泡性及其对荞麦面团发酵特性的影响。结果表明:PP-XGC的起泡性、泡沫稳定性、乳化性和表面疏水性随着pH的升高而增加;与对照组(未添加PP-XGC的荞麦面团)相比,添加PP-XGC降低了面团的黏度和回生值,增加了面团的发酵高度,改善了面团的稳定性和抗老化性。二级结构分析表明,与对照组相比,β-转角含量和无规则卷曲含量上升。拉曼光谱分析表明,PP-XGC的添加可以改善荞麦面团的发酵特性。微观结构分析表明,在pH 2.67条件下PP-XGC添加量(以荞麦粉质量为基准)为1.0%时,面团品质更佳。

马铃薯蛋白组成、性质及其改性应用研究进展

我国马铃薯加工业的快速发展可以归因于马铃薯主食工业化战略的实施。马铃薯蛋白以其高营养价值和功能而闻名,具有特殊的溶解度,并含有大量在其他植物蛋白中缺乏的酪氨酸。因此,马铃薯蛋白在各种市场应用上具有巨大的潜力。本文对马铃薯蛋白的组成、功能性质、改性方法和改性应用进行了全面的综述。马铃薯蛋白具有良好的溶解性、发泡化和乳化特性、凝胶性和抗氧化活性。目前,酶法和微生物发酵是马铃薯蛋白改性研究的重点。此外,本文还概述了马铃薯蛋白中普遍存在的主要问题,并根据目前的研究进展提出了未来的发展前景。未来,应深入研究马铃薯蛋白分子结构与其功能活性的联系;马铃薯蛋白与其他植物蛋白的综合利用;酶法和微生物发酵可作为未来改性方向,利用微生物资源降低改性成本。

不同复热方式对添加甘薯蛋白水解物的冷冻预烤制面包品质的影响

前期研究表明,添加甘薯蛋白水解物(SPPH)能有效改善冷冻面团的品质。本研究在此基础上,以面包的损失率、含水量、硬度和色差为考察指标,在解冻或非解冻的条件下,探究微波、蒸汽和烘烤3种复热方式下SPPH对冷冻预烤制面包品质的影响。结果表明,与解冻组相比,非解冻复热后的面包品质均显著高于进行解冻前处理的面包。在相同复热条件下,SPPH组的冷冻预烤制面包具有更低的复热损失率,更高的含水量和更小的硬度,其中蒸汽复热组的品质最好,复热后的损失率仅降低了4.29%,水分质量分数由36.98%增加至39.38%,面包皮的硬度仅增加了0.27%。从色泽上看,烘烤复热组的面包表皮深褐色加深最为明显。综合各项指标,非解冻处理SPPH组的蒸汽复热方式复热效果最佳。SPPH的添加能够改善冷冻预烤制面包及其复热后的品质。

马铃薯StRac5、StRac7和StRac13基因的克隆及其表达模式分析

探究马铃薯基因的表达模式,为后续研究基因对马铃薯病害的抗性影响提供理论依据。以马铃薯为试验材料,克隆获得3个马铃薯内源小G蛋白基因StRac5、StRac7、StRac13,并对其进行生物信息学分析和表达模式分析。结果表明,StRac5、StRac7、StRac13与拟南芥和水稻中的小G蛋白含有相似的保守序列,均属于ROP蛋白。StRac5和StRac13的蛋白结构域与拟南芥AtRop1、AtRop3、AtRop5、AtRop6及水稻OsRac5、OsRac6、OsRac7相同,StRac7与拟南芥AtRop9的蛋白结构域相同。系统进化树分析表明,StRac7属于第Ⅱ类,与拟南芥AtRop9遗传距离最近;StRac13属于第Ⅲ类,与拟南芥AtRop7遗传距离最近;StRac5属于第Ⅳ类,与水稻OsRac5和OsRac6遗传距离最近。在马铃薯不同组织中,StRac5、StRac7、StRac13基因的相对表达量均为叶>根>茎;与其在茎中表达量比较,StRac5、StRac7和StRac13在叶中的表达量分别增加了1222.4%,2531.3%,468.2%;接种晚疫菌后,StRac5、StRac7和StRac13基因的相对表达量均出现先升高后降低的趋势,StRac5和StRac13基因的相对表达量在接菌24 h后较0 h分别上调了62.2%,40.4%,StRac7基因的相对表达量在接菌72 h后较0 h上调了827.8%;经过ABA、SA、GA和6-BA处理后,StRac5、StRac7、StRac13基因的相对表达量呈现下调的趋势;JA和IAA处理后,StRac5、StRac7、StRac13基因的相对表达量呈现上调的趋势。因此,StRac5、StRac7和StRac13基因能够响应马铃薯晚疫病的侵染,在不同组织和不同激素处理下表达模式也存在一定差异。

Expression in Arabidopsis of a Strawberry Linalool Synthase Gene Under the Control of the Inducible Potato PI2 Promoter

To investigate the role of inducible linalool in Arabidopsis-insect interactions, the FANES 1 linalool synthase （LIS） cDNA from strawberry with plastid targeting and a synthetic intron （LIS＇） was placed under the control of the wound inducible proteinase inhibitor 2 （PI2） promoter from potato. The construct pBin-PPi2-LIS＇ was transformed to Arabidopsis thaliana ecotype Columbia 0. Kanamycin resistant TO seedlings were confirmed for the presence and transcription of the LIS＇ gene by PCR analysis on genomic DNA and by RT-PCR analysis on RNA. Genomic and RT-PCR products were sequenced to confirm correct splicing of the synthetic intron. The expression of active linalool synthase by the PPI2-LIS＇ gene construct in the transgenic lines was assessed by measuring linalool emission using solid phase micro-extraction （SPME） GC-MS measurements after induction with methyl jasmonate. Among 30 tested independent T2 transgenic lines, 10 exhibited linalool production. Linalool expression could be induced by methyl jasmonate treatment, but not by diamondback moth larvae.

酶法改性对甘薯蛋白质结构及理化性质的影响

为研究酶解处理后甘薯蛋白质(sweet potato protein,SPP)结构及理化性质的变化,选用5种蛋白酶(碱性蛋白酶、中性蛋白酶、木瓜蛋白酶、胰蛋白酶和胃蛋白酶)对SPP进行酶解处理,分析蛋白酶酶解产物结构变化,测定其水解度、溶解度、持水性、乳化性等理化指标。结果表明:木瓜蛋白酶和碱性蛋白酶处理后SPP水解度较其他3种蛋白酶处理后更高;SDS-PAGE凝胶电泳图谱显示,经酶解后SPP中处于高分子量的条带被降解为25 ku的低分子量条带;FTIR光谱分析表明,在5种蛋白酶酶解产物的二级结构中α-螺旋和β-转角是其主要结构;木瓜蛋白酶和胰蛋白酶处理后SPP溶解度较高;碱性蛋白酶、木瓜蛋白酶和中性蛋白酶酶解产物持油性、乳化性及起泡性优于其他蛋白酶酶解产物,而胰蛋白酶酶解产物持水性较佳。综上,这一研究可为SPP活性研究及新产品开发提供理论基础。

马铃薯CBFs基因家族的鉴定及其节律性表达分析

马铃薯对光照和温度等信号的敏感性是制约品种区域化种植的重要因素,CBF转录因子在维持植物生长发育和非生物胁迫响应之间的平衡过程中发挥重要作用,但马铃薯CBF基因家族缺少系统性分析.研究通过对马铃薯栽培种CBF基因家族的分析,发现8个StCBF蛋白的结构域较为保守,但基因启动子区存在较大差异.基因节律性表达分析结果显示,生物钟能调控StCBF1a、StCBF3a和StCBF4b的近日节律性表达,且在昼夜交替条件下,StCBF1a、StCBF3a和StCBF4b转录本积累的峰值在傍晚时段.为解析StCBF在环境适应性调控中的生物学功能和探索其在马铃薯遗传改良中的应用提供基础理论支持.

马铃薯块茎蛋白质含量测定方法的比较分析

马铃薯是世界上第三大粮食作物,也是120多个国家13亿多人口的主粮.马铃薯块茎的蛋白质含量是一个重要的营养品质性状,准确、快速、高通量地检测并分析块茎中的蛋白质含量,对于了解马铃薯块茎蛋白的特性,进而加速高蛋白马铃薯育种进程具有重要意义.介绍和对比了不同马铃薯块茎蛋白含量测定方法的原理、样品前处理方法、优缺点以及适用范围,总结了不同蛋白质含量测定方法在马铃薯中的应用现状,并对蛋白质含量测定方法的发展前景进行了讨论,以期为合理选择马铃薯块茎蛋白质含量的测定方法提供参考依据.

不同品种马铃薯全粉蛋白质、氨基酸和矿质元素营养成分差异研究

为研究马铃薯全粉的营养价值,本文测定了14种马铃薯全粉的蛋白质、氨基酸和矿质含量。结果表明:在相同的生长环境下,不同马铃薯品种的营养成分存在显著差异。总蛋白含量平均值为9.81 g/100 g,变幅为7.89~11.81 g/100 g。方差分析结果表明不同肉色马铃薯的蛋白质含量无显著差异。总氨基酸含量平均值为75.70 mg/g,变幅为53.05~98.05 mg/g,必需氨基酸含量占总氨基酸含量的25.23%~46.20%。各氨基酸间的相关性分析表明,除了Tyr和GABA与较多氨基酸的相关性不显著外,其他氨基酸之间都存在显著正相关。在矿质元素含量方面,Fe与Zn元素之间存在显著正相关;Ca元素与Fe和Cu元素呈显著正相关,与Mn、Ni和Se元素呈显著负相关。研究各种马铃薯的成分含量,有助于帮助人们选择不同营养品质的马铃薯,并根据食品加工的需要选择马铃薯品种,也为马铃薯营养品质育种提供理论依据。