## 4 Discussion  
### In Vivo Measurement of the GI of Breads  
From the above results, it can be summarised that IN and GG may be utilised to decrease the post-prandial blood glucose response and decrease the GI of breads. Furthermore, it is clear that the AUCs for Pita breads are lower than Tandoori breads. This might refer to the same results as presented in the microstructure of the bread [8]. It could be attributed to the starch granules of Tandoori bread being more gelatinised and easier for digestive enzymes to hydrolyse and digest and thus increase GI. Moreover, the GI for the combination of all FI also was expected to be similar to the control breads. This is due to the fact that the bread's microstructure reported in our previous work showed similarity in terms of the microstructure of control and bread with all the FI.  
A number of previous studies on the GI of loaf bread with added FI were reported that are in agreement with our results. In a study to find the effect of DFs such as GG on the post-prandial serum glucose, it was found that GG addition significantly reduced GI [10], and GG reduced the GI by 10%. Moreover, it was found that GG decreased post-prandial blood glucose after a meal was served to four volunteers and blood glucose reduced from 114\(\pm\) mg/dL to 86 \(\pm\) 3 mg/dL [11]. In addition, in a study on supplementation of spaghetti with GG, it was summarised that GG significantly reduced hydrolysis of starch and thus decreased GI [12].  
Regarding IN, a number of previous studies have also found that IN can decrease post-prandial blood glucose concentrations. Adding IN to pasta showed that IN significantly slowed down the amount of digested sugar from pasta [5]. Furthermore, a study on the performance of two different types of IN in their degree of crystallisation on the structure and texture of the pasta was conducted, and it was revealed that IN seemed capable of modifying the digestibility of starch, which could consequently reduce the GI. The effect was ascribed to the formation of DFs and protein matrix that acts as a physical barrier and traps the digestive enzyme, and stops them from attaching to starch granules [12]. Moreover, the addition of up to 15% of IN to pasta modified the microstructure of starch in comparison to control, which subsequently changed the digestion of starch. It was found that a reverse relationship between the increase in IN and the number of gelatinised starch granules was seen. This was attributed to the IN stronger affinity to compete with starch granules for moisture, and the starch granules were less hydrolys and thus less available for digestive enzymes [13].  
A few proposed mechanisms are suggested by which FIs modify and reduce the GI curve of food products [14]. Firstly, DF is able to prolong the digestion route of polysaccharides in the stomach. Secondly, gastrointestinal movement changes, prolong transit time and delays digestion. Thirdly, DFs restrict amylase activity to hydrolyse starch granules as they cover the starch granules and extend the distance between granules and digestive enzymes. Finally, DFs form a thick physical barrier that narrows the transfusion of digested saccharides and bloodstream through the small intestine [10,14,15]. Additionally, DFs are fermented by natural microflora in the gut, and short fatty acids are produced [16].