Impact of flour particle size on nutrient and phenolic acid composition of commercial wheat varieties

In the present study, the effect of particle size (PS) on phenolic acid content and proximate composition (moisture, ash, protein, total fat, crude fiber and total carbohydrates) of whole-wheat flour (WWF) was determined. Five different particle size fractions <1.18 to>0.43, <0.43 to>0.30, <0.30 to>0.15, < 0.15 to>0.08 mm, and < 0.08 mm (ASTM recommended), of three commercial wheat varieties (Benazir, TJ-83, Imdad) were used for the present study. Total phenolic acid was determined using HPLC-DAD detections after base hydrolysis of the samples. Proximate composition of each particle size fraction of all three wheat flours were determined by recommended AOAC methods. In all wheat varieties, maximum quantities of total phenolic acids (162.12–554.16 mg/100 g) were obtained from <1.18 to>0.43 mm PS fractions. The maximum moisture content (8.12–8.98 g/100 g) was observed in the two lower PS (<0.15 mm) fractions while ash and protein were highest in the largest PS (<1.18 to>0.43) i.e. 2.10–2.77 mg/100 g and 10.9–11.8 mg/100 g respectively. The total fat (0.24-0.53 mg/100 g) and crude fiber (0.40-0.59 mg/100 g) were highest in <0.43 to>0.30 PS fraction of all wheat varieties. The average carbohydrates (g/100 g) and energy (kilojoules) were ranged from 77.4-79.9, 1502.0-–1518.8 for Imdad; 79.7-84.3, 1518.8-–1527.2 for Benazir; and 78.4-81.1, 1506.2-–1518.8 for TJ-83 wheat varieties. Pearson correlation showed negative correlation between particle size and carbohydrate and energy content and positive correlation with phenolic acids content. This study concludes that particle size has direct influence on the distribution of phenolic acids, carbohydrate, protein, crude fiber, ash, crude fat and moisture in the three wheat varieties.