微生物谷氨酰胺转氨酶改良面粉品质的研究进展

微生物谷氨酰胺转氨酶(MTG)通过催化酰基转移反应,使蛋白质多肽分子内和分子间发生共价交联,从而改善面筋蛋白的结构和功能,进而改善面制品的风味、口感、质地和外观等.论文对微生物谷氨酰胺转氨酶的酶学性质,催化机理,在面粉及面制品上的应用等进行了综述,重点阐述了微生物谷氨酰胺转氨酶在面条、面包、饺子等中国传统面食上的应用,证实微生物谷氨酰胺转氨酶完全能取代传统面粉改良剂,在面粉及面制品上的应用前景广阔.     

谷氨酰胺转胺酶对面条专用粉品质影响的研究

利用微生物生产的谷氨酰胺转胺酶(MTG)对低档面条 专用粉进行品质改良。结果表明,在面条专用粉中添加 0.1％MTG后,其稳定时间、形成时间、评价值、抗延伸性 阻力和拉力比数分别比对照提高了30.0％、43.5％、20.9％、 68.0％和140.0％,其延伸性、粉力则分别比对照降低了 30.1％和2.6％;成品面条的感官评分比对照提高了9.6％, 接近高档面粉制成的同类产品。     

谷氨酰胺转胺酶在面制品中的应用

简要回顾谷氨酰胺转胺酶的发展历史,描述其理化性质和作用机理。详细阐述谷氨酰胺转胺酶在面条、烘焙食品等面制品中的应用,并展望其在食品中广阔的应用前景。     

葡萄糖氧化酶和谷氨酰胺转胺酶在面制品中应用

该文综述葡萄糖氧化酶和谷氨酰胺转胺酶的特性、作用机理,及其对面团流变学特性和面制品品质影响。     

挤压对低温脱脂花生粕氮溶指数的影响

以低温脱脂花生粕为原料,采用挤压技术,在单因素实验的基础上,利用Box-Benhnken的中心组合实验设计原理,氮溶指数(NSI)为考核指标,确定了花生粕挤压改性的最佳工艺条件,建立了数学模型。结果表明,低温脱脂花生粕挤压改性的最佳工艺条件为模孔直径12mm、物料含水量11.8%、挤压温度65℃、螺杆转速300r/min。在该工艺条件下花生粕的NSI为82.20%,和挤压前相比提高15.42%。     

谷氨酰胺转胺酶的功能特性及其在面粉制品加工中的应用

谷氨酰胺转胺酶是一种催化酰基转移反应的转移酶，它可使蛋白分子间和分子内产生共价交联反应，是一种良好的面筋改良剂。主要论述了谷氨酰胺转胺酶的功能特性、作用机理、改良面筋的流变学特性以及它在面粉制品加工中的应用。     

花生蛋白粉的功能特性及对面粉品质的影响

研究了花生蛋白粉的部分功能特性及添加花生蛋白粉对小麦粉品质的影响。研究表明,花生蛋白粉的吸油性保持在0.8～1.2mL/g,持水性在1.0g/g左右,持水性随pH的上升略有上升。在面粉中添加3%的花生蛋白粉面筋筋力最强,添加量为6%时对缓解面粉的弱化速度效果最好,且温度到90℃时,各种添加量面粉的酶仍然有一点活性。     

响应面优化转谷氨酰胺酶改性花生分离蛋白工艺的研究

为了改善花生分离蛋白的凝胶特性,研究了利用转谷氨酰胺酶交联改性花生分离蛋白的工艺。在进行了酶添加量、花生分离蛋白浓度和酶作用时间单因素试验基础上,利用响应面试验设计优化了酶交联改性的最佳条件。并分别测定了酶改性前后花生分离蛋白的功能性,包括:溶解性、吸油性、持水性、乳化性和乳化稳定性、起泡性和起泡稳定性。通过响应面分析得到酶改性的最佳条件:酶添加量、花生分离蛋白质量浓度和酶作用时间分别为17.75 U/g、29.60 g/mL和376 min,在此条件下,凝胶的硬度可达到333.49 g。经转谷氨酰胺酶改性后,花生分离蛋白的吸油性和持水性均有不同程度的提高,分别提高了27.41%和61.24%。     

Expanded functionality of modified whey protein dispersions after transglutaminase catalysis

The functionality of whey dispersions, prepared with a modified whey protein concentrate (mWPC) ingredient, was significantly altered after cross-linking with microbial transglutaminase (TGase) upon pH adjustment to 8. Test TGase-mWPC solutions, pH 8, gelled faster than control mWPC dispersions, as measured in real time; whereas, the gelling temperature of pretreated TGase-mWPC samples (37 °C, 2.5 h) increased from 67.8 to 74.8 °C with a minimal change in gel strength. Prolonged prior incubation with the enzyme (37 °C, 20 h) raised the gel strength in both control mWPC and TGase-mWPC dispersions, though these values were approximately 2.7 times lower in TGase-mWPC samples. Furthermore, the gelling temperature was raised by 9 °C after extensive polymerization. The water holding capacity was not impacted by enzymatic processing while emulsions prepared with TGase-mWPC dispersions proved very stable with no evidence of phase separation during storage at room temperature for 1 mo. Moreover, the apparent viscosity of TGase-mWPC emulsions exhibited a 10-fold increase compared to nonenzyme-treated mWPC samples. The particle size was nearly 11 μm in covalently linked TGase-mWPC test fractions compared with 8 μm in nonpolymerized mWPC dispersions. Ultimately, the functional characteristics of TGase-mWPC ingredients may be designed to deliver superior performance, especially with regard to improving heat and emulsion stability.     

Effects of phenolic acids and transglutaminase on soft wheat flour dough and baked products

BACKGROUND: The effects of phenolic acids on the physical properties of soft wheat flour dough and baked soft wheat flour products were investigated. Transglutaminase (TG) was added to observe the effects of non‐disulfide crosslinks on phenolic acid treated dough. Ferulic acid, p‐coumaric acid or fumaric acid was blended with pastry flour at a level of 250, 500 or 1000 ppm of flour dry weight, respectively. RESULTS: The addition of phenolic acids, TG or a mixture of phenolic acids and TG to flour had no effect on the mixing properties of the doughs but significantly affected 90 min rested dough. The addition of phenolic acids decreased the maximum resistance and increased the extensibility of 90 min rested dough, and TG reversed the effects of phenolic acids on the rested dough. The physical characteristics of cookies blended with each phenolic acid plus TG were not significantly different (P > 0.01) from those of the control cookies. However, TG with and without phenolic acids had significant effects on the moisture content, weight and volume of crackers. CONCLUSION: These results suggest that the addition of phenolic acids and TG in the absence of a fermentation process do not affect the physical properties of soft wheat flour products. The fermentation process allows the chemical reaction of the phenolic acids and TG to occur before the soft wheat flour products are baked. Copyright © 2008 Society of Chemical Industry     

Effect of native and germinated finger millet flour on rheological and sensory characteristics of biscuits

Wheat flour was replaced with native finger millet flour (NFMF) and germinated finger millet flour (GFMF) at 30–50% levels to make soft dough biscuits. Dough rheological properties and baking characteristics of the blends were evaluated. Farinograph data of wheat flour replaced with NFMF and GFMF showed a decrease in water absorption, dough stability and an increase in mixing tolerance index as the level of replacement increased. Extensibility of dough decreased for both NFMF and GFMF as the levels increased. The hardness of biscuit dough measured by texture profile analysis increased from 125 to 234 N for NFMF and 118 to 126 N for GFMF. Scanning electron microscopic studies on the biscuit dough showed polygonal finger millet starch granules adhering to wheat starch granules and protein matrix. The results of the study indicated that the replacement level of 40% with either NFMF or GFMF produced biscuits with acceptable sensory attributes. Addition of sodium stearoyl‐2‐lactylate (SSL) showed further improvement in terms of spread ratio, surface characteristics and texture.     

花生蛋白酸奶的制作及品质特性研究

添加花生蛋白粉制作酸乳,用物性分析仪及感官评定对酸奶各项指标进行测定,探讨花生蛋白添加量、发酵时间、接种量对酸奶品质的影响,通过正交试验确定最佳条件为：发酵时间5h,花生蛋白添加量为15％或20％,发酵剂的接种量为3％或4％。生产的花生蛋白酸奶,口感温和、风味纯正、质地细腻。     

大豆乳清蛋白的面粉增白效果及其对面团流变学特性的影响

研究了大豆乳清蛋白粉对面粉的增白效果,并进一步研究了在增白过程中起主要作用的脂肪氧化酶活性的变化规律。通过考察不同添加量及温度对面粉增白效果的影响,得出大豆乳清蛋白在添加量为2%、温度为30℃条件下增白效果最好。在此基础上采用Brabender粉质仪测定了添加大豆乳清蛋白粉后面团的流变学特性。粉质实验表明面粉的吸水率增大,面团的形成时间、稳定时间、断裂时间延长,评价值提高,公差指数及面团弱化值减小。     

Steady and dynamic shear rheological properties of sweet potato flour dispersions

Korean sweet potato flour dispersions at different concentrations (6, 7, 8, 9, and 10%) were evaluated for their steady and dynamic shear rheological properties. The steady shear rheological properties showed that sweet potato flour dispersions at 25 °C showed a shear-thinning fluid (n=0.31–0.41) exhibiting a yield stress. The magnitudes of Casson yield stress (σ_oc), consistency index (K) and apparent viscosity (η_a,100) increased with an increase in concentration. Within the temperature range of 25–70 °C, the apparent viscosity obeyed the Arrhenius temperature relationship with high determination coefficient (R ²=0.97–0.99) with activation energies (Ea) ranging 0.015–0.024 KJ/mol. Both power law and exponential type models were used to establish the relationship between concentration and apparent viscosity (η_a). Magnitudes of G′ and G″ increased with an increase in concentration. G′ values were higher than G″ over the most of the frequency range (0.63–63 rad/s), being frequency dependent. The sweet potato flour dispersions did not closely follow the Cox–Merz rule at concentrations lower than 10%.     

Effect of partially defatted coconut flour on the rheological,physico-sensory characteristics and fatty acid profile of no-added fat rusk

Partially defatted coconut flour (PDCF) as a source of medium chain fatty acids was selected to replace fat in rusk formulation. Effect of replacement of wheat flour with PDCF (10%, 20% and 30%) on quality characteristics of rusk was studied. Increasing PDCF from 0% to 30% decreased farinograph water absorption, amylograph peak viscosity and overall quality score (52.5 to 19.5) of rusk. Use of additive mix, AM (4% dry gluten powder + 0.002% fungal α-amylase) to 20% PDCF, increased the farinograph dough stability, strength of the paste during heating and overall quality score (39.5 to 50.5). The rusk with 20% PDCF + AM was stable up to 30 days, had 1.6, 5.5 times higher protein and dietary fibre contents as compared to control rusk respectively. The fat in the rusk had zero trans fatty acids and contained 66.2% medium chain fatty acids with lauric acid as a major fatty acid.     

Effect of fortification of defatted soy flour on sensory and rheological properties of wheat bread

The objective of this study was to determine the effects of soy-fortified bread on the sensory and rheological properties. Ground defatted soy flour was blended with wheat flour at 3%, 7% and 12%. The organoleptic characteristics of soy-fortified wheat breads were carried out by taste panel. The effect of this fortification on the rheological properties of the resulting dough was investigated using farinograph and extensograph for quality assessment of the final product. The ash and protein contents of 3% and 7% wheat–soy bread blends increased compared with control. The results revealed that organoleptic characteristics score such as bendability, appearance, flavour and taste, crust texture and overall acceptability properties of bread containing 3% defatted soy flour was highest even though it is not significantly different. Therefore, we conclude that adding 3% or 7% defatted soy flour actually gives as good a loaf of bread as the 100% wheat bread with higher nutritional quality and acceptable consumer attitude with rheological and sensory characteristics.     

Consumer-based optimization of a third-generation product made from peanut and rice flour

ABSTRACT:  Indirectly puffed snacks were produced by an extrusion process with partially defatted (12% fat) peanut flour (30%, 40%, 50%) at different levels of screw speed (200, 300, 400 rpm) and feed rate (4, 5, 6 kg/h). Extrudates were dried to obtain half-products (11% to 12% MC) followed by puffing with deep-fat frying. The puffed snack prototypes were subjected to consumer acceptance test. Consumers rated higher than 6.0 (= like slightly) for all products produced within the experimental factor ranges on the attributes of crispness and texture, whereas consumer scores for appearance, color, flavor, and overall liking were lower than 6.0 for the product containing 50% peanut flour regardless of screw speed and feed rate. The product extruded with 50% peanut flour at screw speed of 400 rpm and feed rate of 6 kg/h received the lowest score of 5.5 on overall liking in a 9-point hedonic score. Predicted regression models indicated that feed rate had the largest effect on consumer attributes followed by peanut flour and screw speed. From the superimposed contour plot of individual contour plot of consumer attributes, the optimum region was identified as the area beginning at the 42.0% to 43.0% peanut flour and 4.0 kg/h feed rates, rising to a maximum at 45% peanut flour and 4.6 kg/h feed rates and decreasing to the 33.0% to 34.0% peanut flour and 6.0 kg/h feed rates. Verification confirmed the ability of predictive regression models to identify peanut-based snacks, which would be scored higher than 6.0 by consumer evaluation.     

Effect of steaming on the rheological characteristics of wheat flour dough

 The effect of steaming on the various rheological characteristics of wheat flour dough was studied. Steaming of flours at atmospheric pressure for 15 min completely denatured the gluten and reduced the water absorption capacity from 58.4% to 45.0%. Even steaming for just 5 min increased the resistance to extension considerably from 500 BU (Brabender Units) to 1000 BU and the ratio figure (resistance to extension/extensibility) from 4.2 to 27.4, indicating stiffening of the dough. The dough made from steamed flour had a higher hardness value of 91.1 N than the dough made from raw wheat flour which had a value of 51.1 N. The pasting characteristics of flour steamed for 15 min measured in a Rapid Visco Analyser showed increased peak viscosity from 218 rapid visco units (RVU) to 257 RVU as well as increased cold paste viscosity from 175 RVU to 200 RVU and increased hot paste viscosity from 94 RVU to 108 RVU for flour steamed for 15 min. Received: 4 August 1998 / Revised version: 23 October 1998     

Effect of ultrasonic treatment on peanut protein isolate-oat dietary fibre mixture gels induced by transglutaminase

The effects of ultrasonic treatment on the physicochemical properties of transglutaminase-induced gels prepared by the mixture of peanut protein isolate (PPI) and oat dietary fibre (ODF) were investigated. The gel strength and water holding capacity (WHC) of PPI gels and PPI-ODF mixture gels were enhanced after ultrasonic treatment, and ultrasonic PPI-ODF mixture gels had higher gel strength and WHC than ultrasonic PPI gels. The ultrasonic treatment of mixture gels increased the storage modulus, loss modulus and the relative percentage of immobilised water, which formed more continuous and compact gel microstructure, especially ultrasonic treated mixture gel prepared by PPI and 9% of ODF. The decrease of α-helix and the increase of β-sheet and random coil were caused by ultrasonic treatment, which improved the gel strength and WHC of PPI-ODF mixture gels. The results indicated that the ultrasonic treatment would be an effective method for improving gelation properties of PPI-ODF mixture.