Abstract:
Preparing the raw materials of sweet fermented rice by stir-frying at different times and different temperatures can improve the quality of sweet fermented rice. The effects of different stir-frying time and temperatures on the sensory quality of sweet fermented rice with different raw materials were analyzed, and the effects of stir-frying on pH, clarity, alcohol content, total acid, soluble solids content and anthocyanin of sweet fermented rice were also analyzed. Through sensory evaluation of the sweet fermented rice, the sensory scores of the sweet fermented rice after different treatments were obtained. The pH value of different samples was directly measured by a precision pH meter. The clarity of the sample is expressed by transmittance. In the experiment, 20 mL of the processed sweet fermented rice sample was taken and after centrifugation at 3000 r/min for 10 minutes, the supernatant was measured by a spectrophotometer. The alcohol content was measured by the most common density bottle method. The total acid was determined with reference to the relevant method of " Yellow Wine" in GB/T 13662-2018. The total anthocyanin content in sweet fermented rice was determined by the pH difference method:9 mL of 0. 025 mol/L KCl-HCl (pH 1. 0) was added with 1mL sample solution and mixed thoroughly. The absorbance was measured at 520 nm and 700 nm after 110 min. Then 0. 4 mol/L CH 3COONa-HCI (pH 4. 5) was added into the test solution to determine its absorbance. Determination of soluble solids were determined as fol-lows:a certain amount of sweet fermented rice sample was mixed, mashed, and squeezed through 4 layers of gauze. The first few drops were discarded and the remaining solution was collected for testing. According to GB/T 12143-2008 refractometer method, samples were measured with Abbe refractometer at 20℃, and all samples were subjected to 3 parallel tests. The results showed that different stir-frying time and temperature had a significant impact on the sensory quality of sweet fermented rice. The smell, color, taste and other sensory indicators of sweet fermented rice were improved under stir-frying at 200℃ for 2 min and at 160℃ for 5 min. The
L* value of the color value was significantly reduced in sweet fermented rice. The pH value of sweet fermented rice was maintained in the range of 3. 6~4. 5. The clarity changed significantly with the changes of stir-frying time and temperature (
P<0. 05). The alcohol content increased after stir-frying at different times and temperatures. The total acid content was highest when stir-frying was conducted at 200℃ for 5 min and 190℃ for 5 min. The anthocyanin content decreased with the increase of the stir-frying time. The soluble solid content of purple rice and red rice increased with the increase of the stir-frying time and temperature, while, the soluble solid content of yellow millet was basically unchanged. The stir-frying treatment at different times and temperatures had different effects on the sweet fermented rice of different raw materials, which will provided a new perspective and method for improving the quality of sweet fermented rice, as well as a theoretical basis for further development of sweet fermented rice products.