Study On Quality Improving Of Dry-type Instant Rice Noodles

Rice noodles is a Chinese traditional food, which is appreciated by customers, and has a broad market in the southern of China. At present, instant fresh rice noodle has a best sales, but it’s difficult to circulate on the market due to retrogradation and deterioration of noodle quality. The cooking rice noodles circulate easily on the market. However, the cooking time of cooking rice noodles is longer than that of instant fresh rice noodle, which results in inconvenient to eat and affects the sales. With the accelerated pace of life, dry-type instant rice noodles is becoming a new growth point of the market due to its convenient to eat and non-fried instant food that is consistent with the conception of health and nutrition. However, there are lots of disadvantages such as disappointing textural properties, a higher break rate and a longer cooking time, that limit the development of the market of dry-type instant rice noodles. It is necessary to deeply and systematically investigate the quality of dry-type instant rice noodles.In order to improve the quality of dry-type instant rice noodles, based on measuring textural properties, cooking loss, cooking weight, cooking time, color, break rate and microstructure. Firstly, this paper studied effects of three kinds of additives(curdlan, sodium pyrophosphate and cassava acetyl esterification starch) on the quality of dry-type instant rice noodles, and further optimized and obtained their optimal contents by respresponse surface method(RSM); Secondly, the paper investigated influences of semidry grinding and microwave-vacuum drying on the quality of dry-type instant rice noodles; Finally, the paper studied effect of three kinds of processing conditions on the quality of dry-type instant rice noodles, and also obtained the optimal processing conditions using RSM. The main conclusions were as follows:The addition of curdlan, sodium pyrophosphate and cassava acetyl esterification starch reduced cooking time, cooking loss and break rate, increased cooking weight and springiness. Curdlan and sodium pyrophosphate increased hardness and chewiness of dry-type instant rice noodles, while cassava acetyl esterification starch had the opposite trend. Curdlan and cassava acetyl esterification starch increased stickiness, sodium pyrophosphate made the surface of dry-type instant rice noodles smoother. Curdlan could improve lightness and yellowness of dry-type instant rice noodles, however sodium pyrophosphate and cassava acetyl esterification starch only improved lightness and yellowness, respevtively. The additives improved the sensory evaluation, and the microstructures of dry-type instant rice noodles showed that the break rate and cooking loss were significantly affected by the addition of different contents of additives. When sensory evaluation was set as response value, the optimum addition was 1.01% for curdlan, 0.28% for sodium pyrophosphate, and 16% for cassava acetyl esterification starch, respectively. The sensory evaluation was 92, which was higher than other test groups under this condition.Compared with that of dry grinding, the hardness, break rate, cooking weight and cooking time of dry-type instant rice noodles made by semidry grinding increased, whereas the springiness, stickiness and cooking loss had the opposite trend. When taking edible quality into consideration, the best grinding condition for making dry-type instant rice noodles was soaking in 40 ℃ for 1 hour and then passing 80 mesh.The results showed that cooking time, drying time, color and cooking weight were improved along with the increase of the power of microwave-vacuum drying,while adverse impact was also made by the power of microwave-vacuum drying on break rate, cooking loss and texture quality; Drying time, cooking weight and cooking time were improved along with the increase of the vacuum, however cooking loss was increased. In combination with the drying rate and quality, the power of 250 w and the vacuum level of-0.06 MPa to-0.07 MPa were the best conditions.The single factor experiments showed that the hardness, springiness, chewiness were largest and cooking loss, break rate were minimal of dry-type instant rice noodles with water adding content of 45% and retrogradation temperature of 5 ℃,respectively; The springiness was largest and break rate was minimal with retrogradation time of 6 hours, and also had acceptable hardness and cooking loss. Selecting the condition to test, the springiness was 0.9647 which higher than other conditions.The water content of rice flour, retrogradation time and retrogradation temperature of making instant rice noodles were 45%, 6 hours and 5 ℃, respectively. Under this condition, the texture quality, cooking loss and cooking weight, break rate, color, cooking time were improved significantly. When springiness was the response value, the optimum processing conditions were water 45%, retrogradation temperature 4 ℃ and retrogradation time 5.8 hours.