| Germinated brown rice has a high nutritional value,especially cotaining a variety of functional components beneficial to human health such as y-aminobutyric acid(GABA),y-oryzanol and so on.Now the research of germinated brown rice mainly focused on the optimization of germination condition and the enrichment of functional components,the drying methods and processing methods of germinated brown rice have been rarely reported.In this dissertation,effects of the hot air drying,microwave drying and microwave-hot air drying on the quality of germinated brown rice were studied.Further,the paper studied effects of roasting on nutrients,color,powder characteristics,and volatile components in germinated brown rice.Moreover,effects of extrusion,air puffing and microwave puffing on nutrients,color and powder characteristics of germinated brown rice were investigatied.At last,the formula of extruded products containing germinated brown rice that was rich in GABA,mulberry leaves and peanuts was designed and its product was developed.In this dissertation,the major working and findings were summarized as follows:1.Effects of the hot air drying at different temperatures(50,60,70,80 and 90 ℃)and microwave drying at different microwave powder(1.4,1.6,1.8,2.0 and 2.2 W/g)on drying curve,major ingredients,color,rehydration and cooking texture properties of germinated brown rice were investigatied,and the optimal parameters of microwave-hot air drying were determined.The results showed the optimum temperature of the hot air drying of germinated brown rice was 50 ℃.Under this temperature condition,the germinated brown rice was dried to a moisture of 14±0.5%for 75 min and energy consumption was 2.25 kw-h.Reducing sugar,soluble protein and GABA content of drying germinated brown rice at 50 ℃ had no significant difference compared with CK(P>0.05).The hardness of cooked germinated brown rice that was dried at 50 ℃ was significantly lower than other temperatures(P<0.05).Further,the optimum microwave powder of the microwave drying of germinated brown rice was 1.4 W/g.Drying time was 32 min and energy consumption was 0.74 kw-h under this microwave powder condition.Reducing sugar,soluble protein,GABA content,rehydration ratio and L*value of drying germinated brown rice at 1.4 W/g were higher than other microwave powder,but reducing sugar and soluble protein content was significantly lower than CK(P<0.05).Rehydration ratio and L*value of drying germinated brown rice at 1.4 W/g were lower than 50 ℃.The hardness of cooked germinated brown rice that was dried at 1.4 W/g was higher than 50 ℃.Finally,the optimal processing parameters of microwave-hot air drying were obtained:the pre-microwave powder of 1.4 W/g,the germinated brown rice was dried to the moisture content of 29%,then the hot air temperature was 50 ℃.Under this condition,reducing sugar,soluble protein and GABA content were not significantly different compared to CK(P>0.05).Rehydration ratio and L*value were basically the same as those of drying germinated brown rice at 50 ℃.In addition,the time of the microwave-hot air drying of germinated brown rice under the optimal conditions shorted 11 min than 50 ℃.Dying time of microwave-hot air drying both was shorter than the hot air drying and it retained more nutrients than microwave.So it was best drying methods for germinated brown rice under the experimental conditions.2.Study the effects of different roasting degree on the quality of germinated brown rice,the changes in major ingredients,colour and flavor volatile compounds of mild,moderate and intensive roasting germinated brown rice were investigated,respectively.Results showed that the reducing sugar,soluble protein and WSI in the germinated brown rice by roasting to three different degree were significantly lower than those without roasting(P<0.05),but there were no significant difference among them(P>0.05).GABA content significantly reduced with the increase of the roasting degree(P<0.05).Total phenolic content in intensive roasting germinated brown rice was significantly higher than those in the others(P<0.05).After roasting,the contents of amylose and resistant starch increased,but no significant difference were found among them(P>0.05).Roasting had little effect on the total starch content(P>0.05).With the increase of roasting degree,a*,b*,△ E and WAI value increased,whereas L*value decreased.By using headspace solid-phase micro-extraction(HS-SPME),together with gas chromatography and mass spectrometry(GC-MS),the flavor volatile compounds of germinated brown rice without roasting and with different roasting degree were extracted,identified and analyzed.It was found that the kinds and contents of pyrazines and furans significantly increased.And the loss of GABA content in mild roasting germinated brown rice was least,and it had the most relative content of pyrazines that could be a major factor contributing towards baked fragrance.So mild roasting was more appropriate for germinated brown rice.3.Effects of extrusion,air puffing and microwave puffing on nutrients,color,water solubility index and water absorption index of germinated brown rice were investigatied.The results showed compared with the raw materials,the three puffing methods reduced the reducing sugar,soluble protein,GABA content and L*value,but increased insoluble protein content and water absorption index.Moreover,extrusion significantly had lower total starch and amylose content(P<0.05),but the the impact of air and microwave puffing was not significant(P>0.05).Microwave puffing significantly increased resistant starch content(P<0.05),while the impact of extrusion and air puffing was not significant(P>0.05).Air and microwave puffing significantly reduced water solubility index(P<0.05),and extrusion significantly increased water solubility index(P<0.05).Compared with the air and microwave puffing,reducing sugar,soluble protein,GABA content of extruded germinated brown rice were less loss,a*,b*and AE values were lowest,and L*value,WAI and WSI were highest.In summary,extruded germinated brown rice not only retained most beneficial nutrients,but also improved the maximum extent of their water solubility and water absorption index.4.With germinated brown rice,mulberry leaves and peanuts as raw material,mixture design test programs was conducted for extruded products development.Statistical analysis of data using Design Expert software was carried out to build a regression model for sensory evaluation score.Based on comprehensive consideration of these sensory evaluation score,the optimal formulation of extrudates was found to consist of 80%germinated brown rice,3%mulberry leaves and 17%peanuts.The maximum predicted value of sensory evaluation score reached 44.3.The formula of extrudates was riched in GABA and other various functional components.In addition,the product had good sensory quality. |
PDF Full Text Request