Development Of High Dietary Fiber Extruded Instant Rice

Convenience food is included in the priority development goal in the plan of China’s food industry.Convenience staple food is the main direction of convenience food development.Instant rice is a staple food product comparable to instant noodles.Its appearance,flavor and taste are basically the same as ordinary rice,which can meet the consumption needs of the majority of rice consumers.A lot of broken rice will be produced in the process of rice milling,and its nutritional composition is similar to that of rice,but its cost is less than half of that of rice.Broken rice has high nutritional value and low price,so it is one of the high quality raw materials for the development of extruded instant rice.However,with the continuous development of the market of extruded instant rice,single extruded instant rice is difficult to adapt to different consumer groups.Diversified,nutritious and healthy extruded instant rice will become the first choice of consumers.The development of extruded instant rice tends to miscellaneous grains and eutrophication.Due to the change of dietary structure,the intake of dietary fiber is getting less and less,coupled with the continuous promotion of healthy diet culture,people’s demand for dietary fiber is increasing day by day.Oat is a kind of miscellaneous grains rich in dietary fiber,which can be added to the formula of extruded instant rice as excipients to make up for the lack of dietary fiber intake.In this paper,with the goal of developing high dietary fiber extruded instant rice with good comprehensive quality,the comprehensive quality evaluation model of extruded instant rice was established to screen the pretreatment methods and adding amount of oats.and to explore the mechanism of its effect on the quality characteristics of high dietary fiber extruded instant rice.The main contents and results of this paper are as follows:1.Quality evaluation of extruded instant rice19 kinds of best-selling extruded rice products were selected to explore the difference and correlation among the main quality indexes of different kinds of instant rice.The comprehensive quality evaluation model of extruded instant rice was constructed by principal component analysis,the evaluation indexes were screened,and the extruded instant rice products were classified by systematic cluster analysis.Compared with other types of instant rice and fresh rice,the feasibility of quality evaluation of extruded instant rice was verified.The results showed that there are great differences in rehydration properties and texture quality indexes of different brands of extruded instant rice.The hardness and stickiness of extruded instant rice were significantly positively correlated with the rehydration time(P<0.01),and negatively correlated with palatability,taste,texture and sensory score of cold rice(P<0.05).The cumulative contribution rate of the three principal components extracted by principal component analysis reached 81.24%,and the comprehensive quality evaluation model was obtained.Finally,Ninteen kinds of samples were divided into three categories based on the comprehensive score of extruded instant rice.According to the quality correlation index,it was found that the samples with high comprehensive score and sensory score had longer rehydration time,higher hardness and stickiness,and their index characteristics were more similar to japonica rice and smaller than indica fresh rice.Therefore,hardness,stickiness and rehydration time can be used as key indexes to evaluate the quality of extruded instant rice.2.Analysis of the characteristics of different pretreated oats on high dietary fiber extruded instant riceCompared with unpretreated oat powder,the raw material characteristics and quality characteristics of extruded instant rice were determined by measuring the raw material characteristics of 6 kinds of pretreated oat and chopped rice(oat: chopped rice = 1:4),and the correlation between the indexes was analyzed.Based on the comprehensive quality evaluation model of extruded instant rice,the most suitable oat pretreatment method for preparing high dietary fiber extruded instant rice was selected.The results showed that the dietary fiber content of extruded instant rice with atmospheric steamed oat was the highest,reaching 7.91%,and the effect of germinated oats on the gelatinization properties of mixed powder of raw materials was significant(P<0.05).The WSI(water solubility index)of germinated oats added before extrusion was the highest(P < 0.05),and the WSI of the samples with fried oats after extrusion was the highest.The odor and taste scores of the samples with fried oats were the highest,and the sensory and comprehensive scores of extruded instant rice with atmospheric steamed oat were better.The peak viscosity and valley viscosity of raw materials were negatively correlated with hardness,stickiness and comprehensive score of rice(P<0.05),and positively correlated with sensory score(P<0.05).Therefore,atmospheric steaming can be used as an oat pretreatment method to improve the comprehensive quality of high dietary fiber extruded instant rice.3.Analysis of the effect of atmospheric steamed oat on the characteristics of high dietary fiber extruded instant riceThe atmospheric steamed oat suitable for preparing high dietary fiber extruded instant rice was selected and mixed with broken rice flour according to five gradients of 26%,32%,38%,44% and 50%.Extruded instant rice with different dietary fiber content was prepared,and the effects of different amounts of atmospheric steamed oat on the physical and chemical properties of raw materials and edible quality of the products were analyzed.Taking the comprehensive score of extruded instant rice as the evaluation index,the best addition of atmospheric steamed oat was determined.The results showed that the dietary fiber content of extruded instant rice increased with the increase of dietary fiber content,and the highest dietary fiber content reached 13.24%.The attenuation value and valley viscosity of extruded instant rice showed extreme value at 44%.The gelatinization degree was the lowest when the addition was 44%,and the extruded WAI(water absorption index)and SP(swelling power)decreased gradually with the increase of the addition.The hardness and stickiness appeared at 44% at the extreme value,the rehydration time extended with the increase of the addition.The valley viscosity of raw materials was significantly negatively correlated with hardness of instant rice(P < 0.01),and negatively correlated with viscosity and comprehensive score(P<0.05).Breakdown was positively correlated with hardness and stickiness(P<0.01),positively correlated with comprehensive score(P<0.05).Therefore,the addition of 44% atmospheric steamed oats can effectively improve the comprehensive quality of high dietary fiber extruded instant rice.4、Quality Analysis of Extruded Instant Rice with High Dietary FiberThe quality of optimal high dietary fiber extruded instant rice and high dietary fiber extruded instant rice(unpretreated blank control group),the commercial high dietary fiber instant rice and the commercial extruded instant rice were analyzed,and their microstructure was characterized.The differences of edible quality,intelligent electronic senses and in vitro digestion characteristics of four kinds of instant rice were studied.The results show that the surface of commercial high dietary fiber instant rice starch is smooth and the internal structure is dense,while the surface fragments of the best high dietary fiber extruded instant rice particles are small and more,the internal pores are dense.The correlation index of edible quality of the best high dietary fiber extruded instant rice are closest to the commercial extruded instant rice.The effective taste evaluation indexes of four kinds of instant rice are bitterness,freshness and sweetness.The best high dietary fiber extruded instant rice has the highest freshness.The main volatile compounds of four kinds of instant rice samples include organic sulfides,small molecular nitroxides,short-chain alkanes and alcohols.The RS content of high dietary fiber extruded instant rice was close to that of commercial high dietary fiber instant rice,and the content of SDS(slow digestible starch)was higher.