The Study On Palatability Evaluation And Material Adaptability Of Instant Rice

Instant rice, also known as minute rice, has been increasingly favored by consumerssince it began to be put on the market in the middle of1980s, and of which industrialproduction gradually moves toward maturely. However, there are still some problems such aspoor taste for instant rice. Palatability of instant rice is not only related with the productiontechnique, but also has the close relation with the quality characteristics of raw material. It hasbeen focused on palatability evaluation and selection of raw materials for instant rice. In thestudy,93paddy varieties as raw materials were collected for the appearance quality,physicochemical properties, cooking quality, RVA profile characteristics and sensoryevaluation, textural properties of instant rice from northeast, central and other regions. Basedon the correlation between instant rice quality and rice properties, the palatability evaluationmodel of instant rice and material adaptability were evaluated by factor analysis and clusteranalysis.First, the correlation of sensory quality and textural properties, and the identification offlavor components in instant rice were discussed. The results showed that moderate hardness,low viscosity, small stickness/hardness value could make the instant rice taste good. A totalof41volatile compounds of instant rice were identified, and18important flavor compoundscould probably be referenced as the main characteristics of quantification of volatilecompounds for instant rice.9volatiles of hexanal, octanal,2-pentylfuran, nonanal, decanal,(E)-2-nonenal,(E)-2-octenal,(E, E)-2,4-decadienal, and1-octen-3-ol may be the mostpotential volatiles that contribute significantly to the aroma of instant rice.Secondly, the correlation between instant rice quality and rice properties was studied. theinstant rice palatability had a higher values when ricewas high whiteness, short length, bigthickness, low amylose content, low protein content and high moisture content. Similarly,when water uptake ratio and volume expansion ratio were lower, iodine blue value and solidsin cooking residual of the rice cooking quality were higher, there would be better taste ofinstant rice. Additionally, RVA pasting properties had a good correlation with instant ricequality, the higher peak viscosity, trough viscosity, final viscosity and peak time, the lowerbreak down, the higher the quality of instant rice, and eating better.Thirdly, multiple linear regression equations about palatability evaluation model ofinstant rice were established by the dependent variable of overall acceptance, appearance,taste and edibility, respectively. By correlation coefficient test, F-test, T-test and hypothesistesting of residuals, the results showed that regression equations were significant and theirgoodness of fit were good. So regression models have the practical significance.Finally, the adaptability of raw rice was facilitated by factor analysis and cluster analysisand the optimal value range of12indicators of rice quality suitable for processing into instantrice were summarized: trough viscosity (1300~2000cP), final viscosity (2000~2800cP), peakviscosity (2000~2500cP), set back (900~1200cP), peak time (>6min), pasting temperature(63~75℃), amylose content (15.5%~17.5%, dry basis), protein content (<8%, dry basis),water uptake ratio (230%~275%), volume expansion ratio (300%~340%), iodine blue value(>0.18) and solids in cooking residual (>20mg/g).