Effect Of Wheat Gluten On Noodle Quality

Noodle is one of the main food in China and its quality has attracted more and moreattention in recent years. Gluten is the main component of the flour and has dramaticallyeffect on noodle quality. In this paper, gluten and starch were firstly isolated from the flourand then three methods were chosen to modify the gluten: Acetic anhydride acylation wasused to reduce the free amino groups in gluten; Glutamine transaminase was used to removeamide group; Sodium sulfite was used to break the disulfide bond. Noodles were made byrecombining the starch and modified gluten in different ratio and the differences of thetexture and cooking characteristics of the two kinds of noodles were analyzed. Innermechanism of the influences of the gluten on noodles were found out by studying withSDS-PAGE electrophoresis and Scanning electron microscopy. The results are shown asfollow:1. Acetylated gluten has various influences on the texture, tensile properties andcooking characteristics of noodles. The SDS-sedimentation value of reorganized flourdecreased with the increase content of Acetylated gluten. The hardness, cohesiveness,breaking length of raw noodles decreased. Springiness shows increase and then keeps stable.The hardness and resilience decreased, and the water absorption of noodles decreased.Meanwhile, the dry matter loss and protein loss increased.2. After the deamidation of gluten, the SDS-sedimentation value and gluten index ofthe reorganized flour decreased. With the increase of the content of deamidation gluten, thehardness, springiness and resilience of raw noodle decreased; while the cohesivenessincreased. The hardness, springiness, cohesiveness and resilience of cooked noodlesdecreased. The tensile properties of raw and cooked noodles get worse. The waterabsorption, dry matter loss and protein loss increased.3. With the increase of concentration of sodium sulfite, the content of free sulfhydryl inthe modified gluten increased; the content of free sulfhydryl reduced while making noodles.With the additive amount of modified gluten by sodium sulfite, the springiness and breaking length of raw noodle decreased, while cohesiveness, adhesiveness and breaking strengthincreased. The springiness adhesiveness, chewiness, breaking strength and breaking lengthdecreased. The water absorption, dry matter loss and protein loss decreased.4. By comparing the SDS-PAGE of gluten, Acetylated gluten, deamidated gluten andreduced gluten, the protein was not hydrolyzed. So it can be deducted that the changes ofnoodle quality were caused by the modification of functional groups in protein.5. The pictures of electron microscope scanning showed that with the increase ofmodified gluten, the network of noodles structure become out of continuity. More and morestarch granules embedded in the network gradually exposed to the surface of the structure.