ผลของการให้ความร้อนในช่วงอุณหภูมิเจลาติไนเซชันต่อสมบัติทางเคมี สมบัติกายภาพ และสมบัติเชิงหน้าที่ของสตาร์ชถั่วมะแฮะ Cajanus cajan (L.) / รพีพร ประสาท = Effects of heat treatment in the gelatinization temperature range on chemical, physical and functional properties of pigeon pea Cajanus cajan (L.) starch
This research aimed to study the effects of heat treatment in the gelatinization temperature range on chemical, physical, and functional properties of pigeon pea starch Cajanus cajan (L). The experiment was divided into two parts. The first part was to study the chemical and physical properties of pigeon pea starch. The study showed that the main component of the pigeon pea starch was carbohydrate (98.95%). The starch also contained fiber (0.64%), fat (0.27%), ash (0.10%), protein (0.04%) on dry weight basis, and 64.61% amylose. The L*, a* and b* of the starch equaled 76.09, -0.61 and +1.16 respectively. The pigeon pea starch granules were round and oval with smooth surface with the average size of 27.32 microns and the crystal structure was of type C. The starch water binding capacity was 0.74 g water / g dry starch. The swelling power (g / g starch dry) and solubility (%) was 2.41 and 1.29, respectively, at 70 ℃ and increased to 10.89 and 10.84 at 95 ℃. From the RVA measurments, the starch pasted at 81.28 ℃. The peak viscosity, breakdown and setback were 4,106.50, 1,082.50 and 2,812.50 cP, respectively. The temperature of gelatinization was 70.95-83.95 ℃ with ∆H[subscript gel] of 12.97 J/g. The gel of starch gave higher G' than G'' at all test frequencies. The amount of resistant starch was 8.35%. The second step was to study the effects of heat treatment in the gelatinization temperature range on chemical, physical, and functional properties. The study employed 30% starch dispersion for modification between 24 to 72 hours at 70 ℃ to 78 ℃. The study showed that all modified starches had reduced amylose. The modified starches did not differ in color (p> 0.05). However, starch granules with rough surface and the crystal structure type C were unchanged. The water binding capacity was in the 1.38 to 1.87 (g / g dry starch) range. The swelling power (g / g dry starch) and solubility (%) were 1.97 and 2.23 at 70 ℃ and increased to 2.09 and 11.92 respectively at 95 ℃. The starch paste showed lower peak viscosity, final viscosity, breakdown and setback and higher pasting temperature when the modification temperature and time increased. The ∆H[subscript gel] tended to decrease while the temperature and the time of gelatinization increased. Starch gel from the modified pigeon pea starch gave higher G' than G'' after modified at 70 ℃ for 24 hr upto 74 ℃ for 72 hr. At higher temperature of modification, the starch gel gave higher G'' than G'. An increase in temperature and time of modification caused an increase in the amount of resistant starch.