Background and objectives Soaking is a processing treatment used in different grain. The objective of the present work is to study the water absorption of bulgur (precooked, dried, and debranned durum wheat), at various temperatures (35, 50, 60 and 65°C) by measuring the moisture content with respect to time. The effect of soaking time and temperature on three dimensions was examined (length: “a (mm)”; crease side width: “b (mm)”; secondary width: “c (mm)”). Weight, volume, sphericity, and density of the precooked, dried, and debranned wheat kernel were also measured. Findings The results indicated higher water absorption capacity at higher temperature. Peleg's model was successfully used to evaluate water absorption during soaking. Peleg's model constants were investigated relative to temperature and confirmed a higher absorption capacity of water. Moreover, during soaking, all the dimensions as well as weight and volume percentages increased with time and temperature. The percent change of secondary width “c” was affected by both temperature and time soaked, indicating that it was the most important parameter controlling the deformation and shape of the kernel. Conclusion Bulgur kernel had higher water absorption due to the absence of the outer bran layer, which acts as a barrier for water absorption. Significance and novetly Modeling the water absorption of bulgur during soaking and measuring its size is important since it help industries to control the soaking operation and further cooking operation and then to optimize industrial process dishes based with bulgur.

The objective of this study was to determine the influence of two types of dryers (hot air oven and vacuum dryer) and the yellow berry percentage (1.75%, 36.25%, 43.25%) on the drying process and phytochemical content of bulgur. Results showed that the Midilli model successfully described the moisture diffusion during drying at 60 °C in all bulgur samples, where an increase in yellow berry percentage generated an increase in moisture content. Effective diffusion coefficient (Deff) increased significantly (p ≤ 0.05) from 7.05 × 10−11 to 7.82 × 10−11 (m2.s−1) and from 7.73 × 10−11 to 7.82 × 10−11 (m2.s−1) for the hot air oven and vacuum dryer, respectively. However, it decreased significantly with a decrease of yellow berry percentage. It was concluded that the vacuum dryer provided faster and more effective drying than the hot air oven. Total polyphenol (TPC), total flavonoid (TFC), and yellow pigment contents (YPC) of bulgur were investigated. TPC ranged between 0.54 and 0.64 (mg GAE/g dm); TFC varied from 0.48 to 0.61 (mg QE/g dm). The YPC was found to be between 0.066 and 0.079 (mg ß-carotene/100g dm). Yellow berry percentage positively and significantly affected the TPC, TFC, and YPC contents due to the hard separation of the outer layers from the starchy grain during the debranning step.

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.