The impact of milling parameters on physiochemical, nutritional, color, flowability, and functional properties of raw gorgon nut flour fractions

The size reduction of dehulled raw gorgon nut kernels was carried out for varied milling time (30, 60 and 90 s) using a batch type laboratory grinder. The effect of milling time was studied in terms of mass fractions (%), average particle size (mu m), and fineness modulus. The milled raw gorgon nut flour (RGNF) was sieved into six varied particle size fractions (300-75 mu m) using a set of US standard sieves. Differential size fractions were further characterized in terms of physico-chemical; nutritional, color quality, flowability, and functional characteristics. The percent decrease in average flour particle size and fineness modulus was 4.4% and 7.1%, respectively. The protein (7.88-11.18%), amylose (7.63-23.73%), L values (54.92-89.31), b values (4.88-8.63), hue (0.88-1.00), chroma (5.93-8.42), loose bulk density (380.45-669.41 kg/m(3)), tapped density (400.47-812.86 kg/m(3)), carr's index (5.00-20.00%), hausner ratio (1.05-1.25), water solubility index (3.08-10.36%) and swelling index (0.51-1.71) increased; whereas, ash (2.58-0.40%); fiber (2.68-1.46%); total phenols (22.65-1.14 mg GAE/g); DPPH radical scavenging activity (56.37-23.24%); a values (3.63-0.61); water absorption capacity (2.30-1.05 g/g); oil absorption capacity (2.35-0.88 g/g) decreased. Statistically, effect of milling time on measured quality characteristics was found significant. Overall, the average flour particle size and fineness modulus decreased with increase of milling time, but it was observed that particle size has pronounced effect on measured quality characteristics of RGNF fractions. While investigating, it was also found that beyond milling time of 60 s, the flour fractions displayed some undesirable changes as evident from slight deterioration of color and nutritional quality of flour fractions. Thus, after comparing all tested samples, a milling time of 60 s using a batch type laboratory grinder is recommended, to obtain superior quality raw gorgon nut flour for food and allied applications.

Automated summary

This study investigated the effect of varied milling time on the quality characteristics of dehulled raw gorgon nut flour. The results showed that an increase in milling time led to a decrease in the average particle size and fineness modulus of the flour. Particle size was found to have a pronounced effect on the measured quality characteristics. It was also observed that prolonged milling time beyond 60 seconds resulted in slight deterioration of color and nutritional quality of the flour. Therefore, a milling time of 60 seconds using a batch type laboratory grinder is recommended to obtain superior quality raw gorgon nut flour.