Influence Of Waxy Rice And Indocalamus Leaves On The Sensory Quality Of Non-filling Rice Dumpling

Rice dumpling, as a traditional Chinese food, is well received by domestic consumers owing to its unique sensory characteristics. However, at present, the researches that focus on delineating the influence of raw material on rice dumpling texture and flavor were not yet in-depth. Accordingly, in this study, a panel of ten judges were trained to develop a descriptive lexicon for rice dumpling aimed at laying the foundations for its texture and flavor evaluation. Then the correlation between texture attributes of rice dumpling and the properties of glutinous rice flour was investigated. And the predictive models for aroma terms based on major odor-active compounds in rice dumpling were developed for purpose of figuring out the effect of waxy rice and indocalamus leaves on the sensory quality of rice-pudding, which has a significant guiding on raw material selection and quality evaluation of rice-pudding. The main contents and results are as follows:Thirteen commercial non-filling rice dumplings were selected in descriptive analysis. A vocabulary consisted of 3 appearance notes, 12 aroma notes, 4 tastes and 9 texture terms was developed to fully describe the sensory characteristics of non-filling rice dumpling by Spectrum, which provided a basis for further research on the effect of raw material on the sensory quality of rice dumpling.Two batches of non-filling rice dumplings made of six waxy rice and five kinds of indocalamus leaves were used to investigate the influence of materials on their texture. Firstly, both groups were distinguished based on the texture lexicon. The results indicated the texture profile of rice dumpling under the same process conditions seemed to be basically influenced by rice variety and had less relationship with leaf origin and treatment. Rice dumplings made of three Indica rice tended to be harder, stickier, more elastic and chewier than others made of Japonica cultivars. The predictive models of texture terms by texture profile analysis(TPA) were developed further in combination with partial least squares regression(PLSR). It showed that among the textural notes generated by the panel, five exhibiting large differences between samples(grain adhesion, adhesion to lips, springiness, hardness and chewiness) could be satisfactorily predicted using TPA parameters(R2≥0.78), while stickiness, cohesivenessof mass, cohesiveness and toothpack didn’t show promising results. Since grain properties serve as rough indicators of textural properties. The study linked the texture attributes of rice dumpling with the properties of glutinous rice. The result revealed that moisture and amylose contents of raw kernels contributed negatively to grain adhesion, adhesion to lips, springiness, hardness and chewiness of rice dumpling, while amylopectin was correlated in a positive manner with most terms. Protein had a negative relationship with stickines. And pasting properties determined by Rapid Visco Analyser(RVA) were positively correlated with the texture of rice dumpling.Based on the flavor lexicon, the differences between samples of both groups were analyzed. The results illustrated that both waxy rice and indocalamus leaves had a great influence on the flavor of rice dumpling. Those made of Japonica cultivars with similar flavor were primarily characterized as having sweet, corn and oily attributes, while other Indica cultivars exhibited relatively large differences in flavor. Also, the differences observed in rice dumplings made of five types of bamboo leaves were significant. Besides, volatile compounds in rice dumpling were extracted by solid-phase microextraction(HS-SPME) and simultaneous distillation extraction(SDE). And the importance of each odor-active compound were assessed by GC-olfactometry(GC-O) and odor active values(OAV). The results showed that a dozen critical compounds were extracted using HS-SPME, while eighteen were identified by SDE. Nine odor-active components proved of primary importance to the aroma of rice dumpling by both of the methods, including hexanal, β-Ionone, nonanal, octanal,(E)-2-Nonenal, 2-pentylfuran, decanal, 2-methoxy-4-vinylphenol and α-Ionone. On the basis of source analysis, among the key aroma components, 2-acetyl-1-pyrroline and 2-methoxy-4-vinylphenol mainly came from glutinous rice, while β-Ionone and α-Ionone were mainly contributed by bamboo leaves. The remaining eight components existed in both of the raw materials with high content.Finally, aroma descriptors were statistically correlated to the concentration of key volatile components in rice dumpling. Sweet, corn and oily notes were accurately predicted by the PLSR models(R2≥0.89). The compounds possessing floral aroma, such as β-Ionone and α-Ionone contributed positively to sweet and corn notes, while those with unpleasant odor, like hexanal, 1-octen-3-ol, 2-pentylfuran, decanal and(E)-2-nonenal were correlated in a negative manner with sweet, corn and oily notes. Also, popcorn aroma could be satisfactorily predicted, which was positively associated with 2-acetyl-1-pyrroline and α-Ionone(R2=0.79). The perception of sour and rancid did not show totally promising results, which appeared to be mainly influenced by hexanal, 1-octen-3-ol and other compounds possessing bad smell. Grain, cooked grain and green terms were not contributed by any of the volatile compounds.