Studies on heat stabilized wheat germ and its influence on rheological characteristics of dough

Wheat germ, a nutrient dense by-product has a very poor shelf life. In order to improve its keeping quality, so that it can be used into different products, various heat treatments were tried and studied to investigate their influence on proximate composition as well as on the rheological characteristics of wheat flour dough. Different heat treatments have shown insignificant effect on proximate composition of wheat germ. Retention of vitamin E was greater in steamed and dried germ. Except for fluidized bed dried germ, all the heat treatments employed completely inactivated the lipase enzyme, whereas the lipoxygenase enzyme was inactivated to an extent of 80–92%. Quality evaluation of germ samples during 60 days storage indicated that steamed and dried germ retained the sensory attributes to a greater extent. Rheological study of wheat flour blends with germ upto 20%, showed marginal increase in water absorption and over-pressure values. However incorporation of treated wheat germ caused dough weakening in terms of reduction in dough stability and rupture at abscissa values.     

Effects of protein hydrolysis on pasting properties of wheat flour

Protein hydrolysis is used widely in the food industry for the purpose of improvement of food or industrial quality, and the processing exists concurrently or subsequently with starch pasting. The effects of protein hydrolysis using papain, pepsin, trypsin, and dithiothreitol (DTT) on flour pasting properties were here investigated at five set concentrations. There were notable decreases in the peak, the trough viscosity, and the integral area of the viscosity curve as the concentrations of papain, trypsin, and DTT increased. DDT and pepsin concentration did not have any effect on final viscosity. Both breakdown and setback showed significant downtrends as the concentration of papain increased but no change as DDT concentration varied. Low concentrations of papain and pepsin prolonged peak time slightly, but higher concentrations shortened it significantly. For trypsin and DTT, low concentrations increased peak time notably, but high concentrations decreased it significantly. Pasting time and temperature increased in the presence of papain, pepsin, and trypsin, more so at higher concentrations. These results supply a basis for the utilization of hydrolyzed protein in the food industry and for the further studies on the interactions between protein and starch during processing.     

麦胚蛋白的研究进展

麦胚是重要的优质全价植物蛋白质营养源,其蛋白质含量达30%左右。本文从麦胚蛋白作为植物蛋白营养源的特点,麦胚清蛋白、麦胚球蛋白、脱脂麦胚蛋白的制备及其理化性质、功能性质,利用脱脂麦胚蛋白作功能性配料及制备麦胚蛋白饮料、氨基酸营养液、生物活性肽等方面对麦胚蛋白国内外研究的最新进展进行了系统的综述,并探讨了进一步研究与开发麦胚蛋白的新途径。     

Effect of phytochemical extracts on the pasting,thermal, and gelling properties of wheat starch

Pasting, thermal and gel textural properties of wheat starch were studied in the presence of phytochemical extracts from pomegranate peel (C18), green tea (C53), Chinese hawthorn (C54), and Chinese gall (C46). All the four extracts increased the breakdown values and reduced the final viscosity. C18, C46, and C53 increased the peak viscosity. C18 and C46 reduced peak time and hot paste viscosity. All the four extracts reduced gel hardness. C46 increased gel adhesiveness. C46 facilitated the gelatinization of starch with earlier onset of T_o, T_p and T_c and a higher melting enthalpy whereas C18 and C54 prolonged the T_o, T_p and T_c and decreased the melting enthalpy. All phytochemical extracts caused earlier onset of T_o and T_p of amylose inclusion complex melting without altering the enthalpy. Scanning electron microscopy revealed that phytochemical extracts could cause looser gel matrices of dried wheat starch gels. Colour observation showed phytochemical extracts imparted different colours to wheat starch gels.     

小麦胚芽提取物的抗肿瘤活性研究进展

小麦胚芽是小麦粉加工的副产品,其中含有多种生理活性物质,已被报道具有抗氧化、抗衰老、抗疲劳和抗肿瘤等活性。近年来,小麦胚芽的抗肿瘤活性得到了越来越多的关注。对近年来国内外关于小麦胚芽提取物抗肿瘤活性的研究进行归纳总结,发现它能够抑制多种肿瘤细胞的生长,具有潜在的抗肿瘤价值,小麦胚芽活性提取物的深入研究和开发可进一步为恶性肿瘤的临床辅助治疗提供新的思路。     

Relationship of polymeric proteins with pasting,gel dynamic- and dough empirical-rheology in different Indian wheat varieties

The protein characteristics of flours from fifteen Indian wheat varieties were studied and related to pasting, gel viscoelasticity and dough properties. The analysis of polymeric proteins showed glutenins, gliadin and glutenin to gliadin ratio ranged between 28.14 and 40.44%, 45.33 and 55.83% and 0.50 and 0.89, respectively. Paste breakdown was low in flours with higher protein content. Viscoelastic properties of flour gels from different varieties showed significant variation and were dependent more on protein than amylose content. The gelation behavior of cooked pastes measured during cooling and holding at 10 °C was explained by an equation. Dynamic moduli of gels were positively correlated with total protein content and negatively correlated to the percentage of unextractable polymeric protein (UPP). Dough strength was positively related to UPP and glutenin content.     

Effect of sourdough fermentation on stabilisation,and chemical and nutritional characteristics of wheat germ

Lactic acid bacteria strains were identified from wheat germ by 16S rRNA partial sequencing, subjected to RAPD-PCR typing and screened. Lactobacillus plantarum LB1 and Lactobacillus rossiae LB5 were used as starters to produce sourdough fermented wheat germ (SFWG). The chemical and nutritional characteristics of SFWG were compared to those of the raw wheat germ (RWG). Lipase activity in SFWG was ca. 2.6-fold lower than that found in RWG. As shown by SPME/GC/MS analysis, most of the volatile compounds derived from lipid oxidation during storage (40 days) were at markedly lower levels in SFWG compared to RWG. Fermentation of wheat germ increased of ca. 50% the concentration of free amino acids. Glu markedly decreased in SFWG, due to its conversion in GABA. The concentration of the anti-nutritional factor raffinose also decreased in SFWG. The in vitro protein digestibility, the concentration of total phenols, phytase and antioxidant activities were increased by fermentation.     

优化麦胚蛋白粉制备工艺的研究

本文对麦胚蛋白粉的制备工艺进行了研究，并利用正交实验确定了制备蛋白粉的最佳磨浆工艺条件为：浸泡温度为70℃，浸泡料水比为1：10，磨浆温度为75℃，磨浆料水比为1：9，制得的麦胚蛋白粉蛋白质的含量为45．0％，麦胚蛋白氮可溶解性指数达到52．6％。     

Effect of hydrocolloids on the rheological, microscopic, mass transfer characteristics during frying and quality characteristics of puri

Effect of hydrocolloids such as guar gum (GG), arabic gum (AG), carrageenan (CG), locust bean gum (LBG), xanthan gum (XN), hydroxypropyl methylcellulose (HPMC) and carboxymethylcellulose (CMC) at 0.5% w/w level on rheological and quality parameters of puri from whole wheat flour was studied. Hydrocolloids like CMC, XN and HPMC increased the water absorption of puri dough, while it decreased in all other samples. The dough development time and mixing tolerance index values increased, while dough stability did not get affected. On addition of hydrocolloid, there was a reduction in the pasting temperature, while the peak viscosity, hot paste viscosity and cold paste viscosity values increased. Hardness, cohesiveness and adhesiveness properties of the puri dough increased with the addition of hydrocolloids. All the hydrocolloids used in general helped in retention of moisture in the puri and hence remained softer and pliable, while there was a significant reduction in the oil content of puri samples containing hydrocolloids. Among the different hydrocolloids used, addition of guar gum at 0.5% w/w level led to puris having improved quality characteristics to a greater extent with respect to moisture retention, lowering of oil content upon frying with softer and pliable texture and better keeping quality. The mass transfer studies confirmed that the mass transfer co-efficient values for moisture loss and oil uptake were lower in puris with guar gum than control.     

Study on the stabilization effect of continuous microwave on wheat germ

The purpose of this research is to study the stabilization effect of microwave on wheat germ using continuous microwave processing equipment. Results from the study indicated that microwave technique had a significant stabilization effect on wheat germ. When the on-line processing capacity of wheat germ was 20 kg/h, the optimal conditions for wheat germ stabilization were microwave power of 4 kW, the processing time of 8 min and ventilation rate of 60 N m³/h. Under such conditions, the residual lipase activity decreased to 14.01% of that of the raw wheat germ. The lipoxygenase lost its activity completely under such intensity microwave processing. After 60 days’ accelerated storage, the acid value increased only 6.56% of that of the stabilized wheat germ before storage. In addition, microwave could cause the death of harmful microorganisms. It was clear that the continuous microwave stabilization process was practicable for wheat germ stabilization.     

Influence of molecular structural characteristics on pasting and thermal properties of acid-methanol-treated rice starches

Rice starches from TKW1, TNG67 and TCS17 varieties, differing widely in amylose contents (0.1, 18.3 and 29.2%) were treated at 45 °C for 1 h in methanol containing various amounts of HCl. The recovery, pasting properties, thermal behaviors, molecular size and chain length distribution of starch were observed. Starches exhibited widely different pasting and thermal behavior upon acid-methanol treated (AMT). Degradation of starches upon AMT affected the leaching extent and chain length of amylose. No obvious changes were found on chain length and content of chain fractions of amylopectin. The pasting viscosity of rice starch decreased with increasing concentration of HCl, and the pasting profiles depended on the variety of rice. The pasting profile of AMT-TNG67 starch showed a two-step increasing pattern during heating, while TKW1 and TCS17 starches showed smoothly increasing pasting curves. The relationship between pasting patterns of AMT-TNG67 starches with amylose leaching and two stages of swelling behavior of starch granules was investigated. Results indicated that the pasting of starch granules depend on the amount, as well as the chain length, of amylose in granules.     

大孔吸附树脂对麦胚肽的吸附特性研究

从大孔吸附树脂对麦胚肽的静态吸附率与解吸率考察了9种树脂的吸附性能，DA201—C大孔吸附树脂吸附特性优于其它8种树脂；吸附流速、麦胚肽的浓度及不同离子强度的样品溶液等对大孔吸附树脂动态吸附性能有影响；DA201-C大孔吸附树脂对麦胚肽的脱盐率为92．13％，麦胚肽的回收率为78．55％：利用不同浓度乙醇可将麦胚肽段按疏水性大小进行初步分离纯化，具有最大疏水性值的75％乙醇洗脱组分清除超氧阴离子自由基（听）的能力最强，其IC50为490．49μg/mL。     

含二十八碳醇的脱脂小麦胚芽饮料的研制

本文研究了含二十八碳醇的小麦胚芽饮料的工艺流程,确定了最佳配方和工艺要点,研究了随 着保存时间延长饮料中二十八碳醇的分布变化情况。     

无机盐对小麦胚芽脂肪酶结构和活性的影响研究

摘 要：为探索一种新型的小麦胚芽稳定化方法,本文采用圆二色谱和荧光光谱对无机盐处理后的商品化麦胚脂肪酶的结构进行了研究,同时,考察了不同无机盐对麦胚中脂肪酶活力及麦胚酸价的影响。研究结果表明,当NaCl浓度为4×10-9 mol/L时,对商品化麦胚脂肪酶的抑制效果最好,其活力降低了21.8%,而KCl对脂肪酶的活力无显著影响,CaCl2和MgCl2均对脂肪酶有激活作用;所选无机盐对脂肪酶二级结构均无明显影响,但NaCl对脂肪酶的三级结构有一定影响;当添加无机盐后,麦胚中的脂肪酶活力和麦胚的酸价均低于未添加无机盐的麦胚,其中1.30%NaCl使脂肪酶活力降低了62.49%,0.75% KCl使脂肪酶活力降低了61.27%。由以上结果可知,添加无机盐可作为有效抑制脂肪酶的活力的手段,利于延长麦胚的贮藏期。     

水解度对麦胚清蛋白酶解物功能特性和抗氧化力影响

利用碱性蛋白酶限制性酶解麦胚清蛋白,研究不同水解度(degree of hydrolysis,DH)酶解物的溶解性、乳化性等功能特性,及对DPPH自由基和羟自由基清除等抗氧化能力。实验结果表明,水解后清蛋白酶解物的溶解性得到改善,DH越高溶解性越好。DH为8.34%时,等电点处的溶解度从未水解时的49.52%提高到74.09%。而乳化性和乳化稳定性随DH的增加而降低。当DH低于7.54%时,酶解物对DPPH自由基和对羟自由基的清除率随DH的提高而增强。浓度为100 mg/mL,DH为7.54%时的酶解物对DPPH自由基清除率达到59.68%。浓度为5 mg/mL时,DH为7.54%时的酶解物对羟自由基清除率达50.23%。      

Effect of cellulose ethers on the microstructure of fried wheat flour-based batters

The effect of type, molecular weight, and concentration of cellulose ethers on the microstructure of fried batter-coated potatoes in two batter systems: controlled viscosity batters (CVB) at 1200 cP and controlled initial moisture content batters (CIMB) at 134 g/100 g flour, were studied by coating cylindrical potatoes (10 mm diameter and 50 mm long) with treatment batters and fried at 160 °C for 3 min. The coatings were separated and their structures were viewed by scanning electron microscopy technique. The micrographs of fried batters showed that different types of cellulose ethers with the same molecular weight and concentration did not affect the microstructures of batters. The viscosity and water content of batters as well as the molecular weight and concentration of cellulose ethers altered the microstructure of fried batters. For CVB, the structure of fried batter containing methylcellulose of higher molecular weight and concentration with simultaneous higher moisture content showed greater hole-size which allowed higher amount of oil penetration through the batter into the food substrate. In contrast, the structure of CIMB with a higher molecular weight and concentration of methylcellulose was relatively more continuous; therefore, it might help in preventing oil penetration into the food substrate.     

A compendium of wheat germ: Separation,stabilization and food applications

BackgroundWheat germ is a precious by-product deriving from the milling industry, as it is a natural concentrated source of essential amino and fatty acids, minerals, vitamins, tocopherols, and phytosterols. However, the presence of high enzymatic activities together with a high content of unsaturated oil, induce a fast decrease in the nutritional value of wheat germ during storage and, consequently, strongly limit product's shelf-life.Scope and approachIn recent decades, flour blends from raw or/and processed wheat germ received great interest from nutritional and technological perspectives. Nevertheless, the quality of the end-product strongly depended on the supplementation level, as well as the type and the severity of separation and stabilization techniques that wheat germ went through. Hence, in this review, the newest advances in wheat germ pre-handling approaches and food applications are discussed to provide relevant and updated information about its worthiness to be a part of the human diet.Key findings and conclusionsTo fully valorize and preserve the nutritious potential of wheat germ, effective pre-treatments of separation and stabilization are needed to guarantee its stability and suitability to meet food quality and safety standards. Such an underutilized ingredient might be a valuable fortifying component for a spectrum of foodstuffs.