Study on determination of the surface viscosity of rice noodles by texture analyzer

In the actual production and cooking process of rice noodles, sticking phenomenon of rice noodles often occurs due to the large surface viscosity, which adversely affects the commodity value and cooking quality of rice noodle product. Sensory evaluation is currently used to evaluate the degree of adhesion of rice noodles. Nevertheless, the accuracy of evaluation results was not high due to the strong subjectivity. In this paper, dried Jiangxi rice noodles from the market were used as raw materials. Surface viscosity of cooked rice noodles was measured with a texture analyzer. Variables such as cooking methods, resting time and measurement conditions (compressing force, test speed and post-test speed) were estimated, taking surface viscosity as indicator. Based on the results, repeatability test was performed. By comparing the coefficient of variation and analyzing the significance of the results, measurement conditions with good repeatability and high sensitivity were selected to establish a method for determining the surface viscosity of rice noodles based on the texture analyzer in order to provide data support for the quality evaluation of rice noodles. Results showed that cooking methods, resting time, compressing force and the post-test speed had significant effects on the surface viscosity of cooked rice noodles (P< 0.05), while insignificant effect was noticed for test speed. The suitable measurement conditions were: rice noodles were boiled for optimal cooking time followed by resting for 5 min before viscosity test. Compressing force was 600 g, test speed was 0.5 mm/s and the post-test speed was 10 mm/s. Under the optimum measurement conditions, all the coefficients of variations of the surface viscosities of other 8 rice noodles were less than 10%, indicating high precision and reproducibility, and differences in the surface viscosity among different rice noodles were significant (P< 0.05).