Effects Of Different Additives On Glycemic Index And Properties Of Extruded Rice

This article added oat dietary fiber,rice protein,or high-amylose corn starch?20%,w/w?to rice flour to obtained extruded rice with oat dietary fiber?DFER?,extruded rice with rice protein?RPER?,extruded rice with high-amylose corn starch?HMER?and extruded rice without any additives through extrusion.Glycemic index?GI?values and in vitro digestibility of various rice before and after cooking were studied to investigate the effects and mechanisms of three additives on the GI values.The physicochemical properties and food quality between three types of extruded rice and extruded rice?ER?,the native rice?NR?were investigated and compared to provide theoretical guidance for the preparation of extruded rice with a lower GI value and good eating quality.The results of the study are as follows:The transparency and appearance color of HMER and ER are close to tha t of the native rice?NR?,while DFER and RPER are yellow-brown and have rough surface.The gelatinization degree of the extruded rice reached more tha n 86%,and the gelatinization degree of HMER was the lowest.The indigestible and high-temperature-resistant V-type crystals were formed in the four groups of extruded rice,and HMER has the highest V-type crystallization peak In add ition,the ratio of 1047cm^-1/1022cm^-1 was 1.00,0.87,0.80 and 0.69,respectivel y,indicating that the addition of oat dietary fiber and high-amylose maize star ch promoted the starch aging of extruded rice,while adding rice protein inhibi ted the starch ageing of the extruded rice.RVA indicates that the disintegration values of ER,DFER,RPER,and HMER was 597.0cp,515.6cp,149.7cp,and54.2cp,respectively.The addition of oat dietary fiber,rice protein,and high a mylose corn starch could all improve the stability of the rice starch paste.The retrogradation values of ER,DFER,RPER,and HMER were 137.2cp,246.2c p,179.0cp,and 18.0cp,respectively,indicating that adding rice protein and oat dietary fiber made the extruded rice much easier to retrograde,and the additi on of high-amylose corn starch could reduce the retrogradation of the extruded rice.The RS?resistant starch?content of NR,ER,DFER,RPER,and HMER was16.5,12.6,13.7,10.5,and 23.8%before cooking.The RS content of the samples after cooking was 5.9,9.8,11.2,7.9 and 15.6%,respectively,and the RDS?fast-digesting starch?content increased significantly.The hydrolysis rate of starch of before and after cooking was higher than that of the native rice,and there was no significant difference among the above three samples.The starch hydrolysis rate of HMER was the lowest before and after cooking.After cooking,GI of each sample was significantly increased.After cooking,the GI value of NR,ER,DFER,RPER,and HMER was 89.5,95.4,92.6,94.1,and 84.5,respectively.It suggested that the addition of high-amylose corn starch significantly reduced the digestibility and GI value of the extruded rice,while the addition of the oat dietary fiber and rice protein had no significant effect on the GI value of extruded rice.There was no significant difference in GL of DFER,RPER and HMER,which was 55.0,54.3 and 56.7,respectively,and NR?64.6?and ER?67.7?had higher GL that the three samples.There was no significant difference in moisture absorption rate,volume expansion rate and aging time among DFER,RPER,HMER and ER.But these indexes of DFER,RPER,HMER and ER were all lower than those of native rice.The solids loss of ER,DFER,RPER and HMER were 2.3,2.6,3.0 and 2.5,respectively.The sensory scores of NR,ER,DFER,RPER,and HMER under optimal cooking conditions were 84.9,74.7,67.5,62.8,and 75.9,respectively.The hardness,viscosity,and elasticity of RPER lower than those of ER,while there was no significant difference in the hardness,viscosity,and elasticity among DFER and HMER and ER.