Abstract:The quality change, during cold storage, in cooked rice subjected to different pressures prior to cooking was investigated. Rice that had been soaked, with a rice-to-water ratio (m/m) of 1:2, at 40 ℃ for 40 min was treated at 200, 400, or 600 MPa for 10 min at 15 ℃. The soaked rice that had not been subjected to ultrahigh-pressure treatment was used as the control. Subsequently, rice was steamed for 15 min, packaged with plastic wrap, and stored at 4 ℃ for 7 d. Indicators related to rice quality were measured daily and compared with the results of the sensory evaluation. The results showed that compared to the control, the hardness of high-pressure treated rice increased slowly; its adhesiveness, iodine blue value, and pH decreased rapidly; and its light transmittance and whiteness increased quickly. The change range of water content in 400 or 600 MPa treated rice was bigger than others. During the storage period, for rice treated at 200 MPa, the whiteness and iodine blue value were the highest, the pH was the lowest, and the sensory score was lower than that of the control. For rice treated at 400 MPa, the hardness, pH, and whiteness were lower and the sensory score was close to that of the control. Rice treated at 600 MPa had a higher hardness and lower whiteness than the control; additionally, its iodine blue value and light transmittance decreased and increased, respectively at the fastest rate, and its sensory score was the lowest and decreased at the fastest rate. Thus, the effect of ultrahigh-pressure treatment at 200, 400, and 600 MPa on the quality of cooked rice was detrimental rather than beneficial.
