Physicochemical and functional properties determination of flour, unmodified starch and acid-modified starch of Philippine-grown sorghum (Sorghum bicolor L. Moench)
2018
Adona, C. E. | Castro, I. J. L. | Castante, R. B. | Tobias, J. R. | Peñarubia, O. R.
Three products were made from Philippine grown sorghum (Sorghum bicolor L. Moench) grains namely: flour, unmodified starch and acid-modified starch. The physicochemical and functional properties of the three products were studied using standard methods. Results showed that the chemical properties of Philippine made sorghum flour were within the limits set by Codex Standard 173-1989 for sorghum flour prodcution. The sorghum starch (unmodified and acid-modified) produced in this study also had higher amounts of ash, fat, protein and fiber content in comparison to rice, corn and cassava starches. In terms of color, the lightness of the Philippine sorghum flour and starch (86-92 L* value) were comparable to rice and corn while cassava flour and starch products were the lightest. The functional properties of sorghum flour and starch showed desirable attributes with amylose content of 25.7–26.30%(db) for flour and 31.5–32.8%(db) for starch. Water absorption capacities of flour and starch were 145% and 96–103%, respectively.The swelling capacity (2–6%) and solubility (1–3%) were minimal. The pasting profile of the three products were significantly different from each other with unmodified sorghum starch having very high peak, trough and final viscosities while the acidmodified starch showed the least values and the sorghum flour being the middle of the two. The gelatinization temperature range of sorghum flour was found to be 63˚C – 77˚C while sorghum starch was in the range of 61˚C - 71˚C. The scanning electron microscopy (SEM) of sorghum flour and starch granules showed that acid-modification can affect the granule structure producing various cracks and disruptions that would have affected the pasting profile of the products. The present findings suggest that the three products have different potential applications and are suitable for making sauces, thickeners and pastries.
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