Instrumental Assessments of Japanese White Salted Noodle Quality

Strong correlations were found between some sensory evaluation results and instrumentally (Instron, Model 4301) assessed quality parameters for Japanese white salted noodles made from 32 Australian wheats. The sensory texture parameter, softness, had a strong negative correlation (r=-0·74, P<0·001) with the instrumental texture parameter, cutting force peak area divided by time. Other sensory texture parameters, smoothness and elasticity, showed significant correlations with another instrumental parameter, compression force peak area divided by time (r=-0·58, P<0·001 and r=0·52, P<0·01 respectively). Brightness, yellowness and discolouration of both raw and cooked noodles were measured using a colorimeter (Minolta, Model CR310). Strong correlations were observed between yellowness and discolouration of raw noodles and CIELAB b* (r=-0·79, P<0·001) and L*a* (r=-0·63, P<0·001) values, respectively. Similar relationships were found for cooked noodles (r=-0·74, P<0·001 for yellowness and r=-0·53, P<0·01 for discolouration). Both flour pasting properties including the flour swelling test and mixograph dough properties showed strong correlations with instrumental measures of noodle texture. Protein and ash content significantly affected noodle colour. In an attempt to simplify objective noodle quality measurements instrumental texture tests were carried out on flour gels. Textural measurements of flour gels showed that sensory softness of cooked noodles was correlated with an instrumental parameter, cutting peak force divided by time (r=-0·46, P<0·01). However, in this study no strong correlations were found between the smoothness and elasticity of noodles and any parameters of compression force-time profiles derived from gels. Yellowness of flour gels measured by a colorimeter showed a significant correlation with that of cooked noodles (r=-0·68, P<0·001). © 1997 SCI.     

Quality of dried white salted noodles affected by microbial transglutaminase

To examine the potential application of microbial transglutaminase (MTGase) in oriental noodle making, the effects of various MTGase addition levels on the rheological, textural and structural properties of noodles were investigated using good quality (‘Red Bicycle’) and poor quality (‘Sandow’) wheat flours. Addition of MTGase at 5–20 g kg^?1 levels, but not at 1 g kg^?1 level, to the two different wheat flours decreased rapid visco‐analyser (RVA) parameters of hot paste viscosity and final viscosity while increasing breakdown. For fresh white salted noodle dough sheets, the storage modulus (G′) and loss modulus (G″) increased significantly at 1 g kg^?1 MTGase addition for both types of flour, but there was no clear trend with higher levels of MTGase. For dried white salted noodles, textural parameters (tensile force, hardness and gumminess) generally increased, cooking loss was little affected and the yield of the cooked noodle was significantly decreased by MTGase. Color was slightly adversely affected. Scanning electron microscopy (SEM) results indicated that physical properties of dry noodles were improved through the formation of cross‐links [ε‐(γ‐glutamyl)lysine] by MTGase. Copyright © 2005 Society of Chemical Industry     

Cold,gel-like whey protein emulsions by microfluidisation emulsification: Rheological properties and microstructures

Novel cold, gel-like whey protein concentrate (WPC) emulsions at various oil fractions (φ; 0.2–0.6) were formed through thermal pretreatment (at 70 °C for 30 min) and subsequent microfluidisation. The rheogical properties and microstructures, as well as emulsification mechanism of these emulsions were characterised. The rheological analyses indicated that the gel-like emulsions exhibited shear-thinning and predominantly elastic gel behaviours, and the apparent viscosities and the mechanical moduli of the emulsions remarkably and progressively increased with increasing the φ from 0.2 to 0.6. Confocal laser scanning microscopy analyses confirmed close relationships between rheological properties and gel network structures at various φ values. The formation of the gel-like network structure was closely related to the high emulsifying efficiency by microfluidisation. This kind of novel gel-like emulsion might exhibit great potential and be applicable in food formulations, e.g. as a kind of carrier for heat-labile and active ingredients.     

淀粉颗粒形貌表征研究进展

淀粉是一种非常重要的营养物质,同时也是重要的工业原料。在淀粉应用研究中,淀粉的加工及改性一直是研究的热点。近些年,人们对淀粉改性后结构及性能进行了深入的研究,发现淀粉改性对其颗粒形貌有明显影响,导致其性能有一定程度改变。因此,对淀粉改性前后颗粒形貌的表征尤为关键。本文概述了目前淀粉颗粒形貌的表征方法,并对其进行了比较,有助于大家正确选择合适的表征方法。     

Probe diffusion in κ-carrageenan gels determined by fluorescence recovery after photobleaching

The effects of free volume and heterogeneity on probe diffusion in κ-carrageenan gels were determined by fluorescence recovery after photobleaching (FRAP) and rheology. By changing the ionic conditions, biopolymer concentration and end temperature, different microstructures and aggregation kinetics in the κ-carrageenan gels were evaluated. The results of the FRAP measurements were compared to transmission electron microscopy (TEM) and nuclear magnetic resonance diffusometry (NMRd) data from previous studies. The results showed that the free diffusion rates of the probe (FITC dextran) in water were influenced by both temperature and ionic conditions. The free diffusion values were used for normalization of the diffusion rates in the κ-carrageenan gel measurements. The compatibility between FITC dextran with different molecular weights (10 and 500 kDa) and κ-carrageenan was evaluated. The results showed that the larger FITC dextran probe phase separates; therefore only the 10 kDa FITC dextran probe was used in the FRAP experiments. FRAP measurements and NMRd probe diffusion in combination with TEM in κ-carrageenan revealed that the void space, degree of aggregation and heterogeneity influence the probe diffusion rate. The κ-carrageenan gelation was analyzed at different end temperatures using rheology and FRAP. The FITC dextran probe diffusion was not influenced by κ-carrageenan aggregation, regardless of rheological gelation kinetics and storage modulus near the gel point. This indicates that the average void space between the gel strands is larger than the size of the probe. Good correlation between the microstructure and the probe diffusion rate in κ-carrageenan gel with different ionic conditions and constant biopolymer concentration were obtained with TEM and FRAP.     

利用差示扫描量热仪研究小米淀粉及小米粉的糊化特性

采用差示扫描量热仪（differential scanning calorimeter,DSC）研究NaCl添加量、蔗糖添加量及pH值对小米淀粉和小米粉糊化特性的影响,并用SPSS软件进行相关性及显著性分析,将小米淀粉和小米粉的糊化特性进行对比。结果表明：相同测试条件下,小米淀粉的糊化温度（包括糊化起始温度T0、峰值温度Tp、糊化终止温度Tc）比小米粉糊化温度低（2.65±0.87） ℃;糊化热焓值（ΔH）比小米粉高（2.51±0.32） J/g;添加NaCl的小米淀粉及小米粉的糊化温度比添加蔗糖的糊化温度高（4.30±1.24） ℃。酸性条件抑制小米淀粉的糊化作用,碱的存在则促进体系糊化。     

Microstructure of Buckwheat and Barley During Malting Observed by Confocal Scanning Laser Microscopy and Scanning Electron Microscopy

The structures of buckwheat and barley were observed by Scanning Electron Microscopy (SEM) and Confocal Scanning Laser Microscopy (CSLM) throughout the malting process. SEM and CSLM have different merits when studying grains and seeds. SEM can be used to study the detailed structure (high magnifications can be achieved) and CSLM to study the overall change in structure during processing. SEM proved that buckwheat starch is degraded by both pitting and surface erosion. A concentric sphere structure was visible when buckwheat starch granules were partly broken down. With CSLM, the organization of protein and starch of buckwheat and barley could be examined independently in projections and images visualizing the 3D structure. CSLM proved that buckwheat starch is surrounded by a protein matrix. Buckwheat protein was structured and surrounded starch granules, while barley protein was present in an amorphous mass through the endosperm. The differences in overall structure between unmalted and malted seeds were evident, as the starch and protein in both the barley and buckwheat were degraded. CSLM may be used in the future to couple processing characteristics to the structure of grains and seeds.     

Properties of MTGase treated gluten film

Water barrier and mechanical properties of gluten film affected by the treatment of microbial transglutaminase (MTGase) were evaluated with the water vapor permeability (WVP), magnetic resonance imaging (MRI) T₂ map and mechanical properties of gluten films. The water barrier ability of gluten films was superior to the no film but inferior to the Parafilm^® investigated by MRI T₂ maps in a two-gelatin-gel system. The WVP of gluten film increased, while the tensile force decreased, with increasing in the dosage of MTGase treated. The gluten films were also dyed with Acid Fuchsin and observed by a confocal laser scanning microscopy (CLSM) to localize the proteins in the film. The micrographs showed many pores and inhomogenous gluten network in MTGase treated gluten films. High WVP and weak mechanical properties of MTGase treated gluten films were attributed to the cross-link bonds formation, which created pores and inhomogenous gluten matrix as evidenced by CLSM.     

扫描电镜法分析常见可食用淀粉颗粒的超微形貌

运用扫描电镜对多种常见可食用淀粉颗粒的超微形貌进行观察,按照淀粉颗粒形貌差别,将考察的所有种类淀粉颗粒分为：块茎形、棒形、球形、扁平形、复粒结构、棱角圆滑和棱角尖锐多面体形及肾形等类别,对每一类及每一种淀粉颗粒超微形貌的特征都分别进行分析和总结,并归纳淀粉颗粒超微形貌特征规律。在本研究成果的基础上初步形成可食用淀粉颗粒超微形貌电镜照片集锦,为从淀粉颗粒超微形貌特征上加强国内淀粉产品的质量监管提供可靠参考。