Effects of soy protein isolate and egg white solids on the physicochemical properties of gluten-free bread

Gluten-free formulations are often supplemented with proteins to improve their quality. To determine the effects of alternative proteins on a hydroxypropyl methylcellulose (HPMC)-treated gluten-free dough system, soy protein isolate was added at 1%, 2% and 3% while egg white solids were investigated at 5%, 10% and 15%. The formulated doughs were analysed using thermoanalytic and rheological techniques to determine the role of water and subsequent flow behaviour upon hydrocolloid addition. The baked loaves were measured for specific loaf volume and tensile strength to determine bread quality. The addition of soy protein isolate and egg white solids (5% and 10%) reduced dough stability by suppressing HPMC functionality, reducing available water, weakening HPMC interactions with the starch matrix and reducing foam stability. At 15% addition, egg white solids became the primary protein scaffolding in the dough and overcame negative interactions with HPMC, improving the loaf volume. However, this formulation may need further optimisation to meet full consumer acceptability.     

Physico-chemical, textural and sensory properties of a fried cookie system containing soy protein isolate

A fried cookie, with the local name of Yackwa, was prepared by partially replacing wheatflour with soy protein isolate (SPI). The physico‐chemical, textural and sensory characteristics were then investigated. The addition of SPI caused a decrease in fat content and an increase in the moisture and protein content of Yackwa. Dehydration and oil absorption during frying decreased as the level of SPI replacement increased. The dough consistency increased with addition of SPI and was highly correlated with dehydration and oil absorption. Colour determination showed that addition of SPI darkened the external and internal colour of Yackwa, probably because of browning caused by the Maillard reaction. The textural hardness increased with increasing SPI content. The addition of SPI made Yackwa darker, more cracked and liable to fracture, harder and less moist as perceived by sensory panellists. Up to 15% of the wheatflour could be replaced by SPI without diminishing acceptability.     

A rheological characterisation of mashed potatoes enriched with soy protein isolate

The effect of the addition of soy protein isolate (SPI) (0, 15, 30, 45 and 60 g kg⁻¹) on viscoelastic properties, large deformation measurements and microstructure of fresh (FM) and frozen/thawed (F/TM) mashed potatoes was investigated. Rheological data showed weak gel behaviour for both FM and F/TM potatoes without and with added SPI together with a significant decrease of system viscoelasticity (G′ and G″) with increasing SPI volume fraction, primarily attributed to the no interaction between the amylose/amylopectine matrix and the dispersed SPI particles or aggregates as revealed by scanning electron microscopy (SEM). Micrographs also showed that SPI formed white coarse aggregates. A freeze/thaw cycle produced a more significant decrease in viscoelastic functions, due to superior aggregation of denatured SPI and reduced water activity. In F/TM samples, high correlations between small and large deformation measurements were found. Results may be useful for technological applications in SPI-enriched mashed potatoes.     

纳米SiO_x对大豆分离蛋白膜特性的影响研究

旨在探讨纳米SiOx对大豆分离蛋白膜特性的影响。采用正交实验研究了纳米SiOx的表面改性条件,采用IR和SEM检测了改性效果,并测定了纳米SiOx的添加量对SPI膜特性的影响。结果表明:纳米SiOx最优改性工艺为pH3、0.4gSDS、超声功率200W、35℃下改性30min。0.3%的纳米SiOx可使SPI膜的氧气透过率和抗拉伸强度达到最大、水溶性降至最低;随添加量增大,膜透明度降低。     

Influence of hydrocolloids on dough handling and technological properties of gluten-free breads

BackgroundThe development of gluten-free breads has attracted great attention as a result of better diagnoses of relationship between gluten-free products and health. The market demand for gluten-free products is increasing day by day due to growing number of celiac disease cases. Development of gluten-free bread remains a technological challenge due to the key role of gluten in the breadmaking process and in bread structure, appearance, texture and shelf life.Scope and approachThis review covers recent advances in the application of hydrocolloids in dough handling, technological and nutritional properties of gluten-free breads, which affect its quality and value.Key findings and conclusionsGluten-free breads results from the combination of different ingredients and hydrocolloids required to building up network structures responsible for bread quality. Various gluten-free formulations have applied hydrocolloids to mimic the viscoelastic properties of gluten. In addition, the impact of different hydrocolloids on the characteristics of dough and bread quality is known to be highly dependent on raw materials, the nature and quantity of hydrocolloids. Hydrocolloids improve the texture, increase the moisture content and extend the overall quality of bread. The results of the reviewed studies indicate that some of those products were acceptable and presented similar or better sensory attributes than control formulations and some were even comparable to their wheat-based counterparts. Based on successful applications of hydrocolloids, it is suggested that novel nutritious ingredients, combined with hydrocolloids can be added to gluten-free bread formulations to improve the quality of life.     

Comparing the rheological and 3D printing behavior of pea and soy protein isolate pastes

In this study the viscoelastic properties of pea and soy protein pastes with concentrations ranging from 10 to 21%w/w were correlated with their ‘printability’ following extrusion 3D printing. The rheological parameters G´, tanδ and σ_y were affected by the protein concentration, and a different viscoelastic behavior was observed for PPI and SPI pastes. At low protein concentrations (10–16%w/w) SPI presents a more elastic behavior than PPI, whereas at higher protein concentrations (>17%w/w) their rheological behavior was similar. No self-supporting structures could be printed for pastes with protein concentrations <15%w/w. In the protein range of 15–17%w/w, SPI formed more stable 3D printed objects compared to PPI. SPI shows a more elastic structure that increases stability against collapse during 3D printing. At higher protein concentrations for PPI, the increase of G´, σ_y and K counteracted the importance of n and tanδ, resulting in self-supporting 3D printed products comparable to SPI.Industrial relevanceThis work provides a better understanding of the importance of rheology of plant-protein food inks to printability by attempting to establish printing predictors, which is important for the development of new inks for 3D printed foods.     

Impact of fat types on the rheological and textural properties of gluten-free oat dough and cookie

This study investigated the effect of six fats (margarine, butter, lard-LAR, refined palm oil-RPO, refined palm oil with stearin-RPOS, hydrogenated palm oil-HPO) with different solid fat content (SFC) on gluten-free oat dough and cookie properties. RPOS and HPO had the highest SFC. RPO dough was the softest, whereas HPO was the hardest one. Dough hardness was correlated with SFC (r = 0.87). Dough stickiness was positively correlated with dough hardness (r = 0.92). Dough hardness influenced the breaking force of the cookies (r = 0.79). HPO were the hardest cookies. Oscillatory test revealed that HPO dough was the stiffest as well as presented a higher rigidity compared to the other samples as showed by the creep tests. LAR cookies were the darkest, while HPO were the lightest. SFC of fats is the most important composition parameter which influences thermal, textural and rheological properties of the oat dough.     

Influence of selected hydrocolloids on triticale starch rheological properties

The aim of the study was to define the influence of selected nonstarch polysaccharides (guar gum, xanthan gum and arabic gum) on several rheological properties of triticale starch pastes/gels, at constant polysaccharide concentration (6.5 g/100 g). These included pasting characteristics, flow curves at 50 °C and mechanical spectra at 25 °C. It was found that the presence of a gum in a system modified the rheological properties of triticale starch gels/pastes, depending on the type and concentration of the gums. In the case of guar and xanthan gums, higher pasting viscosity was observed and the shear stress was increased compared with native starch. The presence of guar gum reduced the degree of thixotropy hysteresis, negative values for this being found for systems with xanthan in spite of their shear‐thinning behaviour. Systems containing arabic gum displayed lower values of pasting and flow viscosity. The type and concentration of gums added to the polysaccharide influenced the viscoelastic properties of the gels.     

大豆分离蛋白对鱼糜凝胶特性的影响

以大豆分离蛋白和鱼糜为主要原材料,通过单因素试验,考察了大豆分离蛋白的添加方式、添加量、底物浓度、凝胶时间、凝胶温度5个因素对鱼糜凝胶强度的影响。试验结果表明,鱼糜的最佳工艺条件为:大豆分离蛋白添加量7%,与水油的混合比1∶5∶1,凝胶温度45℃,凝胶时间30 min。由方差分析可知,4个因素对鱼糜凝胶强度影响的顺序为:添加量与水混合比凝胶温度凝胶时间。在此最佳工艺条件下做验证试验,得到的鱼糜凝胶强度为631.55 g·cm。     

谷氨酰胺转胺酶改性大豆分离蛋白在低能量肉制品中应用的研究

利用谷氨酰胺转胺酶(MTG)对大豆分离蛋白(SPI)进行改性,并将改性SPI应用于低能量肉制品中。实验表明:除常温黏度外,改性SPI的其他功能性明显优于市售肉用SPI;改性SPI在低能量肉制品中适宜的添加量为5%,改性SPI使产品的固体脂肪乳化稳定性、得率分别比肉用SPI提高了14%和7%,产品的感官指标也明显好于肉用SPI。     

共混改性对大豆分离蛋白膜物理性能影响的研究

主要研究了乙醇、硬脂酸、石蜡、半胱氨酸共混对SPI膜抗拉伸强度、水蒸汽透过系数等物理性能的影响。结果表明,乙醇可缩短成膜时间,提高膜的阻湿性和膜的抗拉强度;硬脂酸和石蜡能明显降低膜的水蒸汽透过系数;添加少量的半胱氨酸可以大大改善蛋白膜的物理性能,特别是在增加SPI膜的抗拉伸强度,降低膜的水蒸汽透过系数方面。硬脂酸-石蜡-半胱氨酸-SPI共混膜展现了非常好的包装材料必须具备的强阻湿性能和强的抗拉伸强度。     

大豆分离蛋白的特性研究

研究水解后不同分子量范围的大豆分离蛋白功能性方面,分子量在1000～2000D时候乳化活性和乳化稳定性最大,分别为176.9mL/g和120min;持水性方面分子量小于1000D时候最大,为66.2%;黏度方面,分子量大于4000D时候最大,为1.8cp;持油率方面分子量范围在大于4000D范围内最大,为378.42%。     

大豆分离蛋白与谷朊粉可食性复合膜研究

该文报道影响大豆分离蛋白与谷朊粉复合膜成膜因素,分析各种因素对复合膜性能影响,并对正交试验结果采用极差分析和综合评分法进行评定,得到制备综合性能良好的可食性膜最佳条件为:谷朊粉与大豆分离蛋白比例为1∶5,甘油量为20%,pH为11,预热处理温度和时间分别为80℃和40min;此时,膜的透光率、拉伸强度、撕裂强度、水分含量和水蒸汽透过率依次为60.5%、38.38MPa、198.02N/mm、13.87%和0.507g·mm/kPa·h·m2。     

基于大豆分离蛋白的环境友好型包装材料研究进展

大豆分离蛋白膜具有良好的气体阻隔性和生物降解性,常通过干法或湿法进行制备,但其较弱的机械性能限制了其在食品体系中的广泛应用。可以通过对蛋白进行改性处理以及与多糖复合等手段提升单一大豆分离蛋白膜的功能特性。该文论述了以大豆分离蛋白为基础物质构建可食膜材料的方法、改性技术以及相关性能指标,并探讨了大豆分离蛋白基可食膜对功能因子的稳定作用以及在食品保鲜方面的应用;同时对研发性能优良、具有多功能的可食用包装材料进行展望,以期为环境友好型包装材料的开发提供参考。     

Effect of sesame protein isolate in partial replacement of milk protein on the rheological,textural and microstructural characteristics of fresh cheese

Soft cheeses were manufactured from bovine milk with the addition of 0–12% sesame protein isolate (SPI) were utilised to investigate rheology, texture and microstructure at different stages of cheese making. SPI addition reduced the speed of milk fermentation, kappa‐casein proteolysis of rennet and elongated the time of cheese curd formation. Renneted milk storage modulus G′_60min was decreased and coagulation time increased with increasing SPI content. Low SPI supplements (4% and 8%) enhanced the hardness, cohesiveness, adhesiveness and gumminess of the soft cheese, while high SPI addition (12%) deteriorated the texture. In the cheese curd gel matrix, SPI distributed as specific SPI‐gel clusters on the surface of curd fractures, stacked or fused with ball‐shaped casein micelles and wrapped up to casein gel strands. In summary, SPI actively interacted with casein colloid throughout the cheese making process.     

Influence of the presence of monoglyceride on the interfacial properties of soy protein isolate

BACKGROUND: This study focused on the contribution of soy protein isolate (SPI), in the absence or presence of monostearin (ME), to surface and interfacial properties as a function of protein concentration and pH, which is relevant to the physical stability of a variety of food systems. RESULTS: An increase in protein content always yielded a rapid decrease in surface tension followed by an evolution towards an asymptotic value. Addition of ME gave rise to mixed SPI/ME films, although the interface became dominated by SPI above the concentration for interfacial saturation. The relative interfacial shear viscosity of SPI films showed a marked dependence on: aging time, which may be attributed to a reorganisation of protein species at the interface with some penetration of hydrophobic parts into the oil phase; shear forces, which may partially reverse this reorganisation, leading to shear‐thickening behaviour; and pH, which is the key factor controlling which SPI species is predominant at the interface. The effect of adding ME also depends on pH, favouring a reinforcement of SPI/ME films only at low pH, at which 3S and 7S fractions are dominant. CONCLUSION: The results obtained indicate that SPI shows excellent potential to favour stabilisation of air/water and oil/water interfaces in food systems. Copyright © 2012 Society of Chemical Industry     

不同分子量葡聚糖对大豆分离蛋白冷致混合凝胶的流变性质和质构性质的影响

为研究不同分子量葡聚糖对大豆分离蛋白冷致凝胶强度的影响,采用流变仪和质构仪等手段进行分析。研究结果表明:GDL诱导的大豆分离蛋白冷致凝胶是一种弱蛋白凝胶,酸化速率随着GDL含量的增加而增加。高酸化速率条件下形成的大豆分离蛋白冷致凝胶的凝胶起始点早且最快达到模量峰值;低酸化速率条件下形成的大豆分离蛋白冷致凝胶的凝胶起始点晚且最终模量较低。不同分子量和浓度的葡聚糖添加会改变大豆分离蛋白冷致凝胶的凝胶强度。同分子量的葡聚糖与大豆分离蛋白混合体系形成的冷致蛋白多糖凝胶随着葡聚糖浓度的增加其粘弹性质呈现先上升后下降的趋势;而随着葡聚糖分子量增加混合凝胶的粘弹性质变化越显著。