|dc.description.abstract||Introduction: The production of reactive oxygen species (ROS) and reactive nitrogen species (ROS) are by-products produced by a cellular redox process. At high levels, these by-products cause oxidative stress which can cause degenerative ailments such as diabetes, rheumatoid arthritis and atherosclerosis. The body produces antioxidants in response to oxidative stress which are either naturally produced in situ or supplied externally through the diet. Intriguingly, polyphenols which are naturally occurring compounds found in fruit, vegetables and cereals have also been discovered to have strong antioxidant nature. Recently, research has been drawn towards the antioxidant and polyphenol profiles of cereals and more importantly in barley (Horedeum vulgare).
Barley is now gaining interest mainly as a functional food but is also a vital component for the beer and whisky industry, this is due to the germination of barley and its increase in alpha-amylase activity.
Objectives: This study aimed to assess the effect of antioxidant and polyphenol content and alpha amylase activity in two varieties of barley during germination and thus add to the current body of literature.
Methods: For alpha-amylase activity both varieties of barley grain were cut along the equatorial plane separating the grain into embryo and non-embryo halves and used in the starch agar diffusion method. To measure antioxidant and polyphenol content both
Ferric-reducing Antioxidant Potential Assay (FRAP) and Folin and Ciocalteau assays were used. The two varieties of barley seed were ground up and supernatant was extracted and used in either a 96 well plate-reader or spectrophotometer.
Results: In alpha-amylase activity, Brewer’s barley (BB), ANOVA showed statistical significance with respect to time (p<0.0001), however a paired t test suggested no significance between embryo and non-embryo halves of the grain at time-points 0, 24 and 48 h. Though, in Distiller’s barley (DB), ANOVA results showed there was no statistical difference between embryo and non-embryo halves and paired t test revealed no significance at time 0, 24 and 48. When embryo included halves of both varieties of barley grains were compared, it found no statistical difference at 0 hours but was significant at 24 h (p<0.001) and at 48 h (p<0.0001). This was repeated again, except embryo excluded halves in both varieties and it again found no significance at 0 h but significance at 24 h (p<0.01) and at 48 h (p<0.0001). A standard curve agar plate was set up with concentrations of 1mg/ml and 2mg/ml to confirm that activity depends on both time and concentration of alpha-amylase. For both FRAP and Folin assays, totally polyphenol and antioxidant content decreased over a germination period of 48 h in both varieties of barley with the exception of a minor increase in polyphenol content in DB over 24 h were it then maintained till end of study (48 h).
Conclusion: As with previous studies, it was found that amylase activity increased with time and concentration for both varieties and both embryo and non-embryo halves of the grain. Highest alpha amylase activity was seen in Brewer’s Barley and lowest was in Distiller’s barley. The effect of germination on both FRAP and Folin assays predominantly suggests that germination decreases both antioxidant and polyphenolic activity of Brewers and Distiller’s barley.
Key words: Barley, Antioxidants, Polyphenols, FRAP, Folin, Alpha-amylase, Germination||en