Effects Of Cooking And Steaming On Phenolic Substances In Rice With Different Processing Accuracy

Excessive refinement of rice not only leads to excessive consumption of raw materials,but also causes a large loss of nutrients.Therefore,in the context of the current shortage of resources and food safety issues,moderate processing has received more and more attention.In recent years,studies have found that the health effects of beneficial active substances in organisms are closely related to the antioxidant activity of phenolic substances,so it is particularly important to study the effects of different processing methods on phenolic substances.Rice is processed and matured before consumption.However,the effects of steaming and boiling two heat treatment methods on phenolic substances and antioxidant activities in rice with different processing precision have not been studied.Therefore,Dao Huaxiang rice and Jiangxi indica rice were used as experimental materials,and rice samples of brown rice,two-way rice milling,four-way rice milling,polishing and color processing were taken as research objects,and two kinds of heats of steaming and cooking were studied.The effects of processing methods on the content,structure,composition and antioxidant activity of rice phenols in different processing precisions were compared.The changes of in vitro digestibility of rice with different processing precision were compared by steaming and boiling.The law of influence of digestibility aims to provide a theoretical basis for the moderate processing,practical application and deeper development and utilization of rice.The experimental results show that after steaming,the contents of free phenol,bound phenol and total phenol in Dao Huaxiang rice and Jiangxi indica rice in five processes with different precisions decreased significantly.The content of seven free phenolic acids in the five processes of Dao Huaxiang rice was significantly reduced.In addition to gallic acid and protocatechuic acid,the content of the bound phenolic acid decreased.Gallic acid increased 19.86 mg GAE/100 gDW,3.72 mg GAE/100 gDW,2.83 mg GAE/100 gDW,2.40 mg GAE/100 gDW,2.29 mg GAE/100 gDW successively in the five processes.The content of protocatechuic acid increased by 19.63 mg GAE/100 gDW,2.12 mg GAE/100 gDW,0.46 mg GAE/100 gDW,0.31 mg GAE/100 gDW and 0.04 mg GAE/100 gDW,respectively.and the total phenolic acid content also decreased.The content of free phenolic acids in Jiangxi indica rice decreased gradually,and the content of phenolic acid in combination increased with the increase of processing precision,and the total phenolic acid content decreased.The content of free,combined and total flavonoids in Dao Huaxiang rice decreased.The content of free flavonoids in Jiangxi indica rice decreased except for the content of myricetin.The content of total flavonoids in Dao Huaxiang rice decreased significantly.The content of myricetin and daidzein in the total flavonoids of Jiangxi indica rice increased with the increase of processing precision.The content of luteolin and naringenin in brown rice also increased,and the other contents decreased.Anthocyanins were not detected in the two kinds of free phenolics in rice.With the increase of processing precision,the content of anthocyanin in Dao Huaxiang rice rose from 0.00 mg Cy-3-O-g/100 gDW to 0.02 mg Cy-3-O-g/100 gDW in brown rice,and the content of bound anthocyanins in other processes increased from 0.00 mg Cy-3-O-g/100 gDW to 0.01 mg Cy-3-O-g/100 gDW,and the amount of bound anthocyanins in brown rice in Jiangxi was slightly increased.After cooking,the contents of free phenol,bound phenol and total phenol in Dao Huaxiang rice and Jiangxi indica rice in five different processes under different precisions decreased significantly,and the content of phenol in Jiangxi indica rice decreased more than that in Dao Huaxiang rice.The content of free phenolic acid was all reduced.Only the content of coumarinic acid in Dao Huaxiang brown rice increased by 17.91%.The content of bound ferulic acid in the five processes in Jiangxi indica rice was increased,among which the brown rice increased by 39.7%,the two-way rice milling increased by 70.07%,the four-way rice milling increased by 130.33%,the polishing increased by 56.73%,and the color processing increased by 39.91%.After cooked,two kinds of rice free type of flavonoid content decreases,the bound type of flavonoids substances,Dao Huaxiang rice,in turn,reduce the rice in the content,Jiangxi indica rice in brown rice by 69.81%,the two-way rice milling by 15.30%,and the four-way rice milling increased by 46.98%,polished rice in the rice milling process content of rice increased by 44.43%,the color processing content increased by 3.15%.The content of protocatechuic acid in both rice brown rice and two rice milling processes increased.The content of ferulic acid in the process increased,the content of other combined phenolic acids decreased,and the composition of phenolic acid did not change.The content of free flavonoids in the two rice varieties decreased,and the content of flavonoids in the rice-scented rice combination decreased in turn.The content of bound flavonoids decreased from brown rice to two-way rice milling process in Jiangxi,and from the four rice milling to the color selection process.The content of flavonoids in Jiangxi indica rice was increased,and the total flavonoids content in the two rice varieties also decreased significantly.The contents of seven free flavonoids in Dao Huaxiang rice with different processing precision were all decreased.In addition to the increased content of myricetin and quercetin in Jiangxi indica rice,the content of flavonoids in other varieties decreased.In addition to luteolin in Dao Huaxiang rice In addition to the increase in the content of naringenin,the content of other combined flavonoids decreased in turn with the increase of processing precision.The two kinds of rice are basically free of anthocyanins,which cause the decomposition of anthocyanins in few brown rice to disappear,the content of combined anthocyanins in Dao Huaxiang rice increases,and the total anthocyanin content also increases,while Jiangxi indica rice The total anthocyanin content in rice from brown rice to four rice milling processes increased,and was not detected in polished and color-selected rice.After steaming and boiling,with the increase of processing precision,the contents of free DPPH,ABTS and T-AOC decreased,the combined content increased,and the total content decreased.The results of the three evaluation methods were consistent.There was still a significant positive correlation between the two rice combination types and total polyphenol content and the three evaluation methods,the phenolic hydroxyl(-OH)and carboxyl(-COOH)bonds in the phenolic acids in the two rice were broken,and one of the benzene rings in the flavonoids broke.Myricetin,the pyran ring in the remaining flavonoids has been cleavage.In vitro,the in vitro digestibility,HI value(hydrolysis index)and GI value(glycemic production index)of the two different processing steps were sequentially increased,which accelerated the digestion process of the rice and the cooked rice.The rate of digestion is higher than the rate of digestion in steamed rice.Steaming and cooking also increase the RDS content(fast-digesting starch)contained in the rice products under different processing precisions of two rice varieties,reducing SDS(slow-digested starch)and RS content(resistant starch),thereby promoting The digestion of rice,the RDS of steamed rice is lower than that after cooking,the SDS is higher,and the RDS of cooked rice is higher.