Microscopic Analysis of in vitro Digested Milled Barley Grains: Influence of Particle Size Heterogeneity

In this study, Scanning Electron Microscopy (SEM) is used to characterize the structure of ground and whole barley grain before and after the exposure to in vitro enzymatic digestion at different incubation times (0, 0.5, 1, 2, 6 and 24 h). SEM analysis showed that digestion started to take place in barley grain fragments after 0.5 h of incubation time. SEM indicated that complete starch digestion is dependent on grain fragment size in barley. Starch digestion seems to be completed after 24 hours of digestion in small fragments of barley grains ( 0.5 mm) which was not the case for larger fragment size ( 1.0mm). In case of whole barley grain, SEM showed that alpha amylase was not capable of penetrating and diffusing through barley grain husk after 24 h of incubation. In conclusion, microscopic examination for in vitro digested milled and unprocessed barley fragments differ in particle size, indicating that the extent of starch digestion is dependent on fragment particle size.