The effect of different processing of linseed on antioxidant efficacy was assessed using in vitro rumen batch culture technique. Experimental treatments were eight different technological treatments of linseed: milled (ML; 1-mm sieve), crushed (CL), extruded crushed (EL; 155-160 °C, 15-20 s), and microwave irradiated (2,450 MHz microwave, 900 W) whole linseed for 10, 30, 60, 120 and 150 seconds (Mic10, Mic30, Mic60, Mic120 and Mic150, respectively). The oven dried (55 °C, 48 h) ground (1-mm sieve) samples were weighted (500 mg) into 125 ml glass bottles (n=9) and incubated in 50 ml buffered rumen fluid (ratio of buffer to rumen fluid was 2:1) at 38.6 °C for 24 h. After incubation, the liquid component from the in vitro batch culture was centrifuged at 2500g for 10 min and the supernatant was used for determination of antioxidant capacity. Exactly 100 mg of oven dried (55 °C, 48 h) residue was placed in a capped centrifuge tube; 4 mL of acidic methanol/water (50:50, v/v; pH 2) was added and the tube was thoroughly shaken at room temperature for 1 h. The tube was centrifuged at 2500g for 10 min and the supernatant was recovered. four millilitres of acetone/water (70:30, v/v) was added to the residue, and shaking and centrifugation were repeated. Methanolic and acetonic extracts were combined and used to determine the antioxidant capacity associated with extractable antioxidants. Antioxidant capacity of the samples was measured on the basis of scavenging activities of the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH˙) radical. In a test tube containing 100 μl of samples, 1.9 ml of DPPH methanolic solution (0.1 mM) was added. Control without test compound was prepared in an identical manner. After 30 min of incubation in the dark at room temperature, the absorbance (A) was measured against a blank (methanol) at 517 nm using spectrophotometer. Inhibition of DPPH radical was calculated and expressed as: Inhibition Percentage (%) = [(A control-A sample)/A control]*100. The DPPH Inhibition were 24.40b, 42.78b, 46.26ab, 26.24b, 21.20b, 73.02a, 84.50a and 35.84b % in rumen liquor; and 10.04a, 4.12b,6.23b,9.95a, 9.71a, 0.44c, -1.83c and 7.70ab% in fermentation residue,for ML, CL, EL, Mic10, Mic30, Mic60, Mic120 and Mic150, respectively (p<0.05). The results showed that Mic60 or Mic120 had higher antioxidative efficacy than the others.

Keywords