Improvement of carbohydrate quality in rice bran using microwave irradiation for Nile Tilapia feed production
2014
Kovitvadhi, Uthaiwan | Thongprajukaew, Karun | Sansuwan, Kanokwan | Kovitvadhi, Satit | Somsueb, Pisamai
This study was performed to evaluate the effects of microwave irradiation duration (0, 10, 20 and 30 min) on chemical composition, physicochemical properties and in vitro carbohydrate digestibility of rice bran. Moisture content was different among irradiated rice brans and decreased with longer irradiation time (P < 0.05). This resulted in an increase in crude protein content on dry matter basis in rice bran irradiated for 10 min (P < 0.05). This also caused a decrease in crude fibre content (P < 0.05) with a relative increase in available carbohydrate (P > 0.05). Lipid and ash contents did not change after irradiation. Microstructure, thermal transition parameters and relative crystallinity were enhanced after irradiation. Changes in these characteristics resulted in the in vitro increase in carbohydrate digestibility using crude digestive enzyme extract from Nile tilapia, Oreochromis niloticus (Linnaeus 1758). The relationship between microwave irradiation times (t) and carbohydrate digestibility (D) could be explained as a third order polynomial regression [D = 0.034t3–1.932t2+ 28.675t + 570.733 (r2= 0.884, P < 0.001, n= 24)]. The results indicate that microwave irradiation for 10 min is appropriate for improving the quality of available carbohydrate in rice bran for tilapia feed production.
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