Physicochemical characterization, antioxidant activity and phenolic acids profile of Tunisian whole cereal grains

Six varieties of Tunisian durum wheat, barley and oat cultivars namely Maali, Karim, Rihane, Manel, Meliane and Ghzella were analyzed for their physicochemical properties, antioxidant activities and phenolic acids profile. Results showed that there are significant (p < 0.05) differences in moisture (11.8-12.8%), proteins (10.98-12.09%), neutral detergent fibre (NDF) (47.67-67.39%), ash (2.4-3.93%), fat (2.6- 6.75%), and carbohydrates (64.78-70.95%) contents between all studied varieties. Cereal grains were also a good source of potassium, sodium, calcium, zinc and iron. The results revealed that oat Meliane (5.9%) and barley Rihane (5.4%) varieties are good sources of dietary fiber β-glucan compared to the other varieties. Rihane, Meliane and Maali varieties had the highest total phenolic, total flavonoids and total condensed tannin contents. Antioxidant activity of whole grain extracts was performed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test and revealed that barley Rihane had the best radical scavenging activity compared to oat and durum wheat varieties. The RP-HPLC analysis revealed that Tunisian barley, oat and durum wheat varieties are a good source of phenolic components and natural antioxidants.