Study on the yellowing of high quality japonica rice before entering the warehouse after harvesting

Abstract

Through the simulation of different climatic conditions (clear,cloudy day and rainy day) before the storage of high-quality japonica rice under laboratory conditions,the yellowing of freshly harvested high-quality japonica rice cultivar Nanjing 9108 under different climates was studied,and the yellowing was observed.The quality changes in the process were measured.The results showed that yellowing did not occur in 35 days at 25 ℃and 30 ℃under sunny conditions,and in the process of yellowing,the yellow-coloured index from 28.02 to 31.02,the fatty acid value was less than 25 mg KOH/100g,the husked rice yield was more than 81%,and head rice yield was less than 55%.Under rainy conditions,80%RH,25 ℃and 30 ℃,there was no yellowing in 35 days.the heat reached 40 ℃,yellowing occured in 20 to 25 days.the heat reached 50 ℃,yellowing occurred in 15 days.90%RH,25 ℃and 30 ℃,yellowing occurred in 35 days.the heat reached 40 ℃,yellowing occurred in 15 to 20 days,the heat reached 40 ℃,yellowing occurred in 15 days； During the yellowing process,the yellow-coloured index from 28.03 to 32.69,the change of fatty acid value was obvious and,followed by the husked rice yield,the first grade of Japonica rice was reduced to the second grade,and the head rice yield was lower than 50%,which was less than the requirement of the third grade of high quality Japonica rice.

Keywords

• high quality japonica rice
• yellowing
• quality change