Effect Of Various Digestion Methods On The In Vitro Starch Digestibility

Carbohydrates are an essential source of energy for people,and also mainly exist in the form of starch.For the starch digestion of human trials were high cost,in vitro digestion model is very important.In the present study,an improved simulated enzymic in vitro digestion model was developed,which selected different starch and took account of the effect of starch-associated proteins on starch digestibility and the ratio of enzyme,as a reference for the glycemic response of the starch digestion in vivo.The results of the study were as follows:For the digestion of the three starches,it was found that hydrochloric acid can cause the native starch to release glucose faster during the initial stages of digestion.For example,when the enzyme activities of a-amylase and starch-glucosidase were 8000 U and 200 U respectively,the digestibility of normal corn starch increased from 23.%to 27.1%,and the digestibility of high amylose corn starch was increased from 4.5%to 7.1%,But pepsin,trypsin and chymotrypsin were not obvious roles in the digestion process,the digestibility of the three starches had no significant difference.Although hydrochloric acid was not promoted in the cooked starch digestion,the addition of hydrochloric acid was closer to the actual stomach digestion.It was necessary to add hydrochloric acid for the starch digestion in vitro.The total enzymatic activity and ratio of a-amylase and amyloglucosidase had great influence on the extent and rate of starch digestion.By comparing the digested results of raw and cooked starch with different enzyme amounts,the rate and extend of starch digestion increased with increasing amyloglucosidase activity at the fixed a-amylase activity.For example,at the fixed activity of ?-amylase(2000 U)and the activity of amyloglucosidase was increased from 50 U to 500 U,the initial digestion of normal corn starch increased from 13.8%to 29.1%,and the digestive rate increased from 0.008 to 0.016.The digestibility of high amylose corn starch increased from 2.3%to 7.6%,and the digestive rate increased from 0.002 to 0.006.At the fixed activity of a-amylase(8000U),the extent and rate of starch digestion had no significant difference when the activity of amyloglucosidase increased from 800 U to 2000 U.It implicated that a-amylase played a more important role in the digestion,and amyloglucosidase mainly broken down the substrate of a-amylase.Different digestive methods were compared and was selected a method for raw and cooked starch.After starch was treated at different temperatures,the structure and digestibility of starch were compared.After heat treatment of the three starches,the granular structure was destroyed and its digestibility was also significantly improved.When the structure of three types of starch was basically similar,the final digestibility of normal corn starch,waxy corn starch and high amylose corn starch were 92.6%,93.7%,and 84.4%,respectively.The digestibility of high amylose maize starch had significant difference compared with the others.It was found that the granular structure of the starch and the characteristics of the amorphous region were the main factors for the starch digestion.