Effects of Enzymatic Hydrolysis of Protein on the Pasting Properties of Different Types of Wheat Flour

Abstract: As one of the most effective methods to modify proteins, enzymatic hydrolysis is used widely in the preparation of wheat products in the food industry. During the same process, starch pasting occurs frequently. The effects of wheat protein hydrolysis with papain, pepsin, and trypsin on the pasting properties of 3 different kinds of flour were investigated in 5 concentrations. Results showed that the peak viscosity, trough, final, and integral area of pasting curve of these flours decreased with increasing enzymatic hydrolysis of protein, and decreased significantly with the increasing enzyme concentrations. Medium‐gluten flour was the least sensitive to enzymatic activity and weak‐gluten the most sensitive. Downtrends appeared with increasing papain and trypsin concentrations in the form of breakdown. Enzymes had no significant different effect on the peak times of strong‐ and medium‐gluten flour, but prolonged peak time slightly in weak‐gluten flour. The pasting time and temperature of strong‐ and medium‐gluten flour were significantly increased in a concentration‐dependent manner. However, there were no significant effects on the pasting times of weak‐gluten flour. These results could supply a basis for utilization of enzymatic hydrolysis of wheat protein in food industry and for further studies into the interactions between hydrolyzed protein and starch in food or processing industries. Practical Application: Illuminating the effects of enzymatic hydrolysis of protein on the pasting properties of different types of wheat flour is very important in food industry. Flour viscosity decreases after enzymatic hydrolysis of protein/gluten. Enzymes have different effects on peak time, pasting time, and pasting temperatures for different types of flour. These results could supply a basis for utilization of enzymatic hydrolysis of wheat protein in food industry and for further studies into the interactions between hydrolyzed protein and starch in food or processing industries.     

Use of the Rapid-Visco-Analyzer to Measure Starch Pasting Properties. Part I: Effect of Sugars

The Rapid Visco-Analyzer (RVA) was used to measure the effects of dextrose, sucrose, corn syrup solids and polydextrose on maize, tapioca and wheat starch pasting properties. The addition of 1 part sugar: 1 part starch tended to decrease peak viscosity, whereas peak viscosity increased at higher sugar concentrations (up to 4 parts sugar: 1 part starch). Time to onset of viscosity increase and time to peak viscosity increased as sugar concentrations increased. Dextrose, sucrose and corn syrup solids increased the maximum setback viscosity, of the starches, but polydextrose reduced setback viscosity. As the molecular weights of the sugars increased, the effects generally increased for maize and tapioca starches but not for wheat starch. Pasting property parameters measured in the RVA concurred with data obtained using other viscometers or by other techniques previously reported. The RVA is useful as an alternative tool for studying starch pasting properties and the effects of food ingredients on starch performance.     

Changes in the structural and physicochemical characterization of pea starch modified by Bacillus-produced α-amylase

In this study, changes in structural and physicochemical properties of pea starch treated with Bacillus-produced α-amylase were determined. The results showed that enzymatically modified pea starch had lower amylose content and granule size but higher branching degree and relative crystallinity. After enzyme hydrolysis, the distribution of A and B1 chains slightly decreased, while the distribution of B2 and B3 chains increased lightly. Enzymatic hydrolysis preferentially occurred in the amorphous region and cannot change the crystalline structure of pea starch. Moreover, pea starch showed lower light transmittance, peak viscosity, breakdown viscosity, pasting temperature, shear viscosity, storage modulus and loss modulus, while the oil adsorption capacity and gelatinization enthalpy significantly increased with increasing α-amylase hydrolysis time. Correlation analysis indicated that α-amylase hydrolysis had different effects on different pea varieties. This research could provide ideas for exploring new applications for enzymatically modified pea starch in food industry.Industrial relevanceThis study found that Bacillus-produced α-amylase significantly changed the amylose content, granule size and viscosity of pea starch, which was helpful to further investigate the modified starch. This technology is expected to widen the applications of pea starch modified by Bacillus-produced α-amylase in food industry, for example as thickener, stabilizer and beverage, to improve the texture, stability and shelf-life of various food products.     

NaCl对氧化淀粉浆料糊化性能的影响

研究NaCl对氧化淀粉浆料糊化性能的影响。采用快速黏度仪(RVA)测试了不同NaCl浓度下氧化淀粉的糊化温度、糊化时间、峰值黏度、终值黏度和回生值。结果表明:随着NaCl对淀粉质量浓度的增大,氧化淀粉的糊化温度、糊化时间和峰值黏度逐渐增大;终值黏度和回生值随着NaCl对淀粉质量浓度的增大,先减小后增大;NaCl对淀粉质量浓度在2%～6%的范围内时,淀粉浆液的低温稳定性和抗老化性能有所提高。     

小米粉RVA糊化特性的研究

采用快速粘度分析仪（Rapid Viscosity Analyser,RVA）测定了在不同浓度、pH及添加蔗糖、食盐、明矾、硬脂酸等条件下小米糊RVA粘度曲线的变化情况,研究了小米淀粉粘度性质及其影响因素。结果显示,浓度对小米糊粘度性质影响显著,随浓度的增高,糊化温度降低,粘度曲线中峰值粘度及最终粘度升高;pH值对小米糊粘度性质影响较大,过高或过低的pH都会导致峰值粘度降低;随蔗糖添加量的增加,糊化温度略有增高;随着氯化钠浓度的增加糊化温度升高,氯化钠可提高小米糊粘度;明矾对小米糊的峰值粘度影响较大,而对糊化温度影响不大;添加硬脂酸的小米糊的最终粘度显著提高,而峰值粘度变化较小。通过研究为进一步了解小米淀粉的粘度特性及产品开发提供理论依据。     

反应程序和淀粉浓度对糯玉米和普通玉米淀粉快速黏度测定谱特征值的影响

以糯玉米品种渝糯7号和普通玉米品种农大108为材料,研究了不同的反应程序和淀粉浓度对其快速黏度测定(RVA)谱特征值的影响,同时比较了糯玉米和普通玉米淀粉在不同反应程序和淀粉浓度条件下的差异。结果表明:(1)玉米淀粉的RVA特征值在不同反应程序下发生了改变,但其没有改变糯玉米和普通玉米之间的差异,在不同反应程序下,相对于普通玉米淀粉,糯玉米淀粉的峰值黏度和沉降值较高,而谷值黏度、终值黏度、回复值、峰值时间和糊化温度较低。(2)糯玉米和普通玉米淀粉的RVA特征值受到浓度影响,随着淀粉浓度的增加,峰值黏度、谷值黏度、沉降值、终值黏度和回复值随之增加,峰值时间略有降低,浓度太低时淀粉不能糊化,在能糊化条件下则随着浓度的增加而降低。在低浓度条件下,糯玉米淀粉的峰值黏度高于普通玉米,而在较高浓度(11%)条件下,糯玉米淀粉的峰值黏度则低于普通玉米淀粉。     

盐对马铃薯淀粉及马铃薯淀粉-黄原胶复配体系特性的影响

研究不同种类以及不同浓度的盐对马铃薯淀粉以及马铃薯淀粉-黄原胶复配体系糊化性质以及流变学性质的影响。结果表明：盐的加入均增加了马铃薯淀粉的成糊温度和回值,降低了峰值黏度、终值黏度和崩解值,且马铃薯淀粉糊的黏度值随着盐浓度的增加先降低后升高,成糊温度随着盐浓度的增加呈现先显著升高后略微下降的趋势。对于马铃薯淀粉-黄原胶复配体系,盐的加入升高了复配体系的成糊温度、峰值黏度和崩解值,并且复配体系的黏度值随着盐浓度的增加而增加。流变学性质表明盐引起马铃薯淀粉糊的假塑性增强,并随着盐浓度的增加假塑性先增强后略有减弱,相反盐引起马铃薯淀粉/黄原胶复配体系的假塑性减弱,并与盐浓度之间没有明显的规律性。     

玉米籽粒品质性状及其相互关系分析

通过测定55个玉米品种（系）籽粒的物理性状、淀粉品质及蛋白质组分，分析它们之间的简单相关关系。结果表明：容重与各淀粉组分含量呈负相关，与角质率、低谷粘度、最终粘度、回冷值、峰值时间、糊化温度呈极显著正相关；角质率与醇溶蛋白、谷蛋白、总蛋白含量及峰值时间和糊化温度呈极显著正相关，与膨胀势、峰值粘度和稀懈值呈显著负相关；直链淀粉含量与稀懈值负相关，与膨胀势、峰值粘度、低谷粘度、最终粘度、回冷值、峰值时间和糊化温度均表现一定的正相关；支链淀粉含量、总淀粉含量以及支／直比与糊化温度正相关，与其它粘度指标负相关；峰值粘度与低谷粘度、稀懈值、最终粘度和回冷值的相关程度较高，是衡量淀粉糊化特性的最重要指标；醇溶蛋白与总蛋白和粘度性状问的关系更密切，醇溶蛋白含量的变化对于总蛋白含量变化及淀粉特性的影响最大。文章还提出今后要加强支链淀粉、峰值时间、糊化温度和醇溶蛋白含量等对加工品质影响的研究。     

Partial Characterization of Tamarind (Tamarindus indica L.) Kernel Starch Oxidized at Different Levels of Sodium Hypochlorite

The effects of different levels of sodium hypochlorite (1–4 g/100 g dry solids active chlorine) on the physicochemical, pasting, and structural properties of tamarind kernel starches were investigated. The isolated starch had low traces of non-starch components, such as protein, fat, and ash, indicating its purity. Both the carboxyl and carbonyl contents in the oxidized starches increased significantly with the increase in chlorine concentration. The introduction of carboxyl and carbonyl groups resulted in significantly lower amylose content. The swelling power of oxidized starches was significantly lower than native starch and the solubility values increased when the chlorine concentration increased at all the measured temperatures. The percentage of light transmittance increased progressively after oxidation. Pasting properties showed that in treatments at high active chlorine concentrations, the peak viscosity decreased more drastically than in treatments at low chlorine concentration, indicating a greater degradation of starch. The morphology of the starches was not altered after oxidation. After oxidative treatment no change in the X-ray diffraction pattern was observed but intensity of the peaks increased. Therefore, tamarind kernel being underutilized raw material, has a great potential as a non-conventional source of starch and desirable properties of this starch can be enhanced by oxidation for applications in food industry.     

核桃蛋白对大米淀粉凝胶化及凝胶特性的影响

研究不同核桃蛋白添加量下大米淀粉的糊化特性、流变特性、热特性及凝胶质构和水分子状态.结果表明,核桃蛋白以浓度依赖的方式降低了大米淀粉糊的黏度和相变焓值,而使糊化温度升高,当核桃蛋白添加质量分数达12％时,峰值黏度、谷值黏度、最终黏度分别降低了 30.77％、12.35％和14.65％,糊化温度升高了 8.89％;所有样...     

Effect of repeated freezing-thawing on structural,physicochemical and digestible properties of normal and waxy starch gels

The normal and waxy corn starch gels were subjected to repeated freeze–thaw treatment at 0, 1, 2, 3, 4,5 and 6 cycles with an interval of 24 h, and the effects on structural, physicochemical and digestible properties were investigated. The normal starch gels formed a honeycomb structure while waxy starch gels exhibited a lamellar structure, and the number of holes and lamellas increased with increasing cycles. The X-ray analysis showed that the A-type pattern of starches was converted into the B-type after treatment, and their relative crystallinity increased with the number of increased freeze–thaw cycles. The hardness increased in both normal and waxy starch. The solubility and pasting breakdown viscosity decreased in normal starch while they increased in waxy starch. The pasting peak time, peak viscosity, and setback viscosity increased in normal starch but decreased in waxy starch. The rapidly digested starch (RDS) and slowly digested starch (SDS) content in normal starch increased and non-digestible starch (RS) content decreased whereas the RDS, SDS and RS content in waxy starch was almost unchanged as the freeze–thaw cycles increased. In the meantime, the molecular weight of both normal and waxy starch decreased with freeze–thaw treatment. Therefore, the repeated freeze–thaw treatment can change the physicochemical and digestible properties which could be a basis for starch-based food processing.     

Effects of enzymatic modification of soybean protein on the pasting and rheological profile of starch–protein systems

Reformulation of traditional food systems to introduce new ingredients may change their structure and perceived texture. Interactions between proteins and starch during processing can markedly influence starch gel network structure and rheological profile. The present work aimed to study the effects of soybean protein and the products of enzymatic modification on the pasting and rheological profile of corn and cassava starch. The behavior of those protein‐enriched gels during storage was also assessed. Soybean protein isolate (SPI) was incubated with endopeptidase (AL) or food grade microbial transglutaminase (TG). Pasting and rheological behavior, water retention capacity, and structure of protein– and hydrolyzed protein–starch gels were analyzed. Protein incorporation increased the viscosity of starch suspension during and after heating. SPI‐modified proteins increased peak viscosity. Only the structural modifications brought by TG on SPI increased the final viscosity during starch pasting and the storage modulus (G′). This modulus (G′) of the gelled systems decreased with the addition of AL‐treated protein isolate. Light and fluorescence microscopy showed that SPI formed a continuous phase, like a network, in the gelled system. Different network structures and rheological properties can be obtained when SPI are modified by protease and TG enzymes, which may be very useful for designing new food products.     

酶改性对食物蛋白过敏原性的影响

酶法改性蛋白技术主要包括酶水解和酶交联方法,它可以改变蛋白质的结构和功能特性,已广泛用于食品加工。酶水解,包括胃蛋白酶、胰蛋白酶、木瓜蛋白酶、碱性蛋白酶、糜蛋白酶,可以水解食物蛋白表面的过敏原表位,从而降低其过敏原性;酶交联,包括转谷酰胺酶、过氧化物酶、多酚氧化酶等,可以通过交联反应促使过敏原蛋白聚合而使其过敏原表位包裹在内部,因而也可以降低食物的过敏原性。总之,酶改性是降低食物蛋白过敏原性的一种有效方法,值得深入研究。     

Effect of the milling process on quality characteristics of rye flour

BACKGROUND: Most of rye flour is obtained by a gradual reduction system using roller flour mills, which generate different flour streams. The study of the different flour streams composition is necessary since it determines the flour quality and the flour uses. Four break streams and nine reduction streams were analysed for moisture, ash, starch, protein, damaged starch, falling number, amylose/amylopectin ratio, β‐glucans and colour. Mixing and pasting properties were also determined with a doughLAB and a Rapid Visco Analyser respectively. RESULTS: As the milling process advanced, moisture and starch content decreased but protein, ash, β‐glucans and damaged starch increased. The differences in composition are probably related to the effect of the roller mills and the increase in the contamination with bran. The absorption, development time, and pasting viscosity increased as the milling proceeded, in detriment of the peak time. The β‐glucan content was positively correlated to absorption, mixing tolerance index and pasting viscosity, and negatively correlated to peak time. CONCLUSION: Differences in composition, above all, in bran, showed different mixing and pasting properties in rye streams. The most different streams corresponded to the last streams in the break process, in the sizings and in the middlings. Copyright © 2008 Society of Chemical Industry     

Availability of amino acids in processed plant-protein foodstuffs

The microbiological availability of 6 essential amino acids in some processed plant protein foodstuffs was assessed with different micro-organisms after digestion with different proteolytic enzymes (papain, pepsin, trypsin, erepsin) or their combinations. Available lysine was also determined with the dinitrofluoro-benzene (DNFB) procedure. The amounts of ‘available’ amino acids were compared with those liberated by supposedly complete hydrolysis. More lysine was found ‘available’ with the DNFB method than with Leuconostoc mesenteroides following digestion with pepsin and trypsin. Digestion with papain released less methionine and tryptophan available for Streptococcus zymogenes than did digestion with pepsin. Treatment with trypsin after digestion with pepsin often increased the liberation of amino acids, whereas digestion with erepsin had little or no additional effect. Methionine and tryptophan were assessed by two procedures, but different results were obtained with different protein sources. Continuous digestion-dialysis did not liberate more lysine, methionine and tryptophan than non-dialysed digests.     

生物酶解法去除大豆蛋白抗原性研究进展

大豆蛋白具有合理的氨基酸组成和较好的加工性能,是食品工业和动物营养中应用最广泛的植物蛋白。但大豆蛋白会导致人和动物的过敏反应,是公认的八大过敏原之一。国内外对消除大豆蛋白抗原性的方法进行了多方面的研究。传统的加热处理效果并不理想,主要原因可能是大豆蛋白分子中存在序列性抗原决定簇。近年来利用生物酶解技术去除大豆蛋白抗原受到高度重视。研究发现,胰蛋白酶、胃蛋白酶等对大豆蛋白分子的水解和降低抗原性效果较差。碱性蛋白酶、木瓜蛋白酶、风味蛋白酶等作用结果较好,但难以完全消除其抗原性。本文重点介绍生物酶解法降低大豆蛋白抗原性的研究进展,对单一酶解法不能完全消除大豆蛋白抗原性以及不同文献所得结果不一致甚至出现相反现象的原因做了适当分析。     

不同苦荞蛋白酶解产物抗氧化活性研究

以苦荞蛋白作为底物,采用碱性蛋白酶Alcalase 2.4 L、木瓜蛋白酶、胃蛋白酶、胰蛋白酶以及胃蛋白酶加胰蛋白酶模拟体内蛋白消化,制备苦荞麦蛋白水解物。采用DPPH及ABTS~+·法比较不同的蛋白水解物与水解前苦荞蛋白的体外抗氧化活性。结果表明:不同蛋白酶水解产物水解度由高到低的顺序为:碱性蛋白酶胃蛋白酶~胰蛋白酶胃蛋白酶木瓜蛋白酶胰蛋白酶,其中碱性蛋白酶水解苦荞蛋白水解度达29.95%。苦荞蛋白本身具有一定的抗氧化能力,其中DPPH清除率及ABTS~+·清除率最高分别达71.91%及11.25%,但均显著低于阳性对照Vc。随着水解程度的增加,苦荞蛋白水解产物抗氧化能力逐渐增强。其中,以碱性蛋白酶酶解产物抗氧化活性最高,其DPPH清除率及ABTS~+·清除率最高分别为91.65%(0.5 mg/mL)及16.67%(1 mg/mL),均显著高于原苦荞蛋白。其中,碱性蛋白酶水解产物的DPPH自由基清除率在高浓度(0.5mg/mL)条件下,与阳性对照Vc持平。同时碱性蛋白酶酶解产物抗氧化性(DPPH清除率及ABTS~+·清除率)显著优于其他蛋白酶解产物。因此,苦荞麦蛋白采用碱性蛋白酶解制备苦荞水解产物可作为天然的抗氧化剂。     

Use of Iodine as a Tool to Understand Wheat Starch Pasting Properties

The ability of iodine to bind amylose has been used to understand a variety of structural and functional aspects of starch in food systems. In this study, the changes in starch granule swelling, polymer leaching and their relationship to pasting properties was investigated by adding iodine to the starch slurry at either room temperature or 95°C. The objective of the study was to investigate the contribution of leached and solubilized starch polymers on the pasting behavior of wheat starch. The addition of very small amounts of iodine (0.1%, dry basis, db) at room temperature increased peak and final pasting viscosities as compared to when no iodine was added. Further increases in iodine concentration resulted in a decrease in peak and final pasting viscosities. The amount of iodine required to completely inhibit granule swelling was more than that required to minimize amylose leaching from the granule. Adding increasing amounts of iodine at 95°C to the starch slurry resulted in the gradual decrease in peak and final pasting viscosities. The contrasting effects of iodine on paste viscosity behavior when added at room temperature or at 95°C suggest that the contribution of extra‐granular amylose on the setback viscosity is minimal and a larger proportion of amylose is retained in the intragranular spaces.     

EFFECT OF SUGAR AND GUMS ON THE PASTING PROPERTIES OF CASSAVA STARCH

Pasting properties of cassava starch solutions were prepared with different types of sugars (glucose, sucrose and fructose) at different levels as 10.71, 19.35, 32.43% and gums (gum acacia, guar gum and gum tragacanth) at 0.1, 0.2, 0.3, 0.4% levels, respectively, were analyzed using the Rapid Visco Analyzer. The pasting temperature increased with increase in the sugar concentration in cassava starch–water system and the maximum 78.27C at 32.43% sucrose solution. The peak viscosity (PV) and breakdown viscosity (BD) decreased with increase in the sugar concentration. Hot paste viscosity and cold paste viscosity decreased progressively with increase in sugar concentration in fructose and glucose solution. The PV and BD increased with increase in guar gum concentration and was maximum 5,704 and 3,773 mPa·s at 0.4% concentration, respectively.

PRACTICAL APPLICATIONS

Cassava starch performs most of the functions where maize, rice and wheat starch are currently used. In food industry, cassava starch is used in extruded snacks for improved expansion, as a thickener in foods, in processed baby foods as a filler material and bonding agent in biscuit and confectionary, textile, pharmaceutical, paper and cosmetic industries. Cassava starch can be converted to maltotriose, maltose, and glucose as well as to other modified sugars and organic acids. Starch from cassava can be used to make gelatin capsules. Starches and gums are often used together in food systems to provide texture, control moisture, water mobility, improve overall product quality and stability, reduce cost and facilitate processing. Cassava starch, due to its high swelling power, is reported to yield better quality instant noodles.     

Effect of genotype and environment on the concentrations of starch and protein in, and the physicochemical properties of starch from, field pea and fababean

BACKGROUND: The effects of genotype and environment and their interaction on the concentrations of starch and protein in, and the amylose content and thermal and pasting properties of starch from, pea and fababean are not well known. RESULTS: Differences due to genotype were observed in the concentrations of starch and protein in pea and fababean, in the onset temperature (To) and peak temperature (Tp) of gelatinization of fababean starch, and in the pasting, trough, cooling and final viscosities of pea starch and fababean starch. Significant two‐way interactions (location × genotype) were observed for the concentration of starch in fababean and the amylose content, To, endothermic enthalpy of gelatinization (ΔH) and trough viscosity of fababean starch. Significant three‐way interactions (location × year × genotype) were observed for the concentration of starch in pea and the pasting, trough, cooling and final viscosities of pea starch. CONCLUSION: Differences observed in the concentrations of starch and protein in pea and fababean were sufficient to be of practical significance to end‐users, but the relatively small differences in amylose content and physicochemical properties of starch from pea and fababean were not. Copyright © 2011 Society of Chemical Industry