Effects Of Main Components In Wheat Flour On Noodle Characteristics

Main flour components have very important effects on noodle quality. The objectives of this study are to investigate the relationship between main sensory properties of noodles and texture profile analysis (TPA), tensile and cutting experimental parameters obtained by TA-XT2i Texture Analyser, to evaluate noodle quality with both objective and sensory methods by fractionation and reconstitution, and to focus on investigating the effects of protein, starch, lipid and their fractions on noodle quality. The present study established new methods to quantitatively assess Chinese noodle quality by the Texture Analyser and provided experimental and theoretical basis for selection of flour for noodle making, improvement of noodle quality, production of flour and breeding of wheat special for noodle making. The main experimental contents and results are as follows:1. Investigation of evaluation methods for noodle qualityThe sensory evaluation indexes were first ascertained as follows: chewiness was an overall index and firmness, elasticity and smoothness were three fundamental indexes. The noodle samples were significantly different by adjusting the flour composition and their instrumental parameters were determined by Texture Analyser. The relationship between instrumental parameters and sensory indexes of noodles was studied. The results indicated: the sensory properties of cooked noodles including chewiness, firmness and elasticity were significantly positively correlated with TPA parameters (hardness, adhesiveness, chewiness, resilience and springiness), cutting stress, shear force, tensile stress and tensile strength obtained by Texture Analyser, respectively. The smoothness of cooked noodles was significantly negatively correlated with TPA parameters (hardness, chewiness, adhesiveness and springiness), cutting stress, tensile stress and tensile strength. This study made an initial exploration of likely evaluating Chinese noodle quality by objective method.2. The effects of protein and starch contents in flour on noodle qualityProtein, starch and their fractions were firstly separated from original flour and then they were respectively added to flour samples for noodle making, in order to investigate the effects of protein content, the ratio of glutenin to gliadin, starch and its fraction content on noodle quality. The results indicated: Protein content of flour was significantly positively correlated with TPA parameters (hardness, springiness, gumminess and chewiness), tensile strength and breaking length. The ratio of glutenin to gliadin in flour was significantly positively correlated with gumminess and chewiness of cooked noodles. With the increasing of acid-insoluble gluten the noodle instrumental textural parameters such as hardness, cohesiveness, gumminess, chewiness, cutting stress and tensile strength were increased.Starch content of flour was highly significantly negatively correlated with TPA parameters (hardness, springiness, gumminess and chewiness), tensile strength and breaking length. Additionally, starch content was significantly positively correlated with water adsorption and cooking loss of noodles. Amylose content in starch showed significantly positive relativity with hardness, gumminess, chewing, cohesiveness and resilience and was markedly negatively correlated with breaking length of noodles.3. The effects of protein fractions in flour on noodle qualityThe proteins in flour are actually a mixture composed of many structurally complicated macromolecules, which is the main factor affecting dough and noodle properties. The results indicated: With the increasing of acid-insoluble gluten the noodle instrumental textural parameters such as hardness, cohesiveness, gumminess, and chewiness were increased, while springiness of noodles remained nearly the same. High molecular weight-glutenin subunits (HMW-GS) contributed much to springiness of cooked noodles and low molecular weight-glutenin subunits (LMW-GS) played an important role in hardness, gumminess, chewiness, resilience and adhesiveness of noodles.α-andβ-gliadins significantly affected noodle resilience andω-gliadin exerted marked influence on tensile strain of noodles. On the other hand,γ-gliadin significantly affected hardness, springiness, chewiness and cutting attributes of cooked noodles and showed minor relativity to noodle tensile strength.4. The effects of lipids in flour on noodle qualityThe effects of lipids in flour on noodle quality were investigated by fractionation and reconstitution methods. The results indicated: as the free lipid content was increased, hardness, gumminess and chewiness of noodles linearly increased, reaching a maximum, thereafter falling to a low value. Among the TPA parameters of the noodle samples, gumminess and chewiness were highly positively correlated with hardness. Free lipid content in flour was significantly negatively correlated with resilience of cooked noodles. Noodle hardness and cooking loss increased with the increment of free lipid in certain extent. The shear force of cooked noodles was significantly positively correlated with their tensile strength and breaking length.Polar lipids markedly influenced hardness, gumminess and chewiness of cooked noodles. Thus, Polar lipids play an important role in obtaining strong noodle texture. Increasing non-polar lipids in flour would weaken noodle springiness.5. Quality investigation of wheat varieties special for noodle makingAccording to wheat protein quality assessment, sensory and instrumental analysis of cooked noodles made from 41 wheat varieties, the quality of noodles was better made from the wheat cultivars containing 5+10, 14+15, 7+8 or 2+12 gluntein subunits. With the increment of 1000-grain weight and bulk density of wheat, the noodle sensory indexes of palatability, toughness, stickiness, appearance and total scores tended to decline. As the flour extraction and ash content of flour were increased, the noodle appearance, palatability, toughness, stickiness, and total scores decreased sharply. With the increasing flour sedimentation value, the noodle appearance, smoothness, taste value and total scores tended to rise.