Effects Of Extrusion On The Physical Properties And Nutritional Quality Of Several Feedstuffs

The nutritional value of feedstuffs may be variable under different extrusion processing conditions.This research was conducted to determine the effects of feed processing factors on the nutritional value of several feedstuffs,such as the contents of crude protein,fat,and some anti-nutritional factor.(1)Effects of extrusion on nutritional quality of corn and soybeanEffects of extrusion on the protein,fat,solubility of protein,heat-sensitive protein,and phytate contents of soybean and corn were investigated.The results showed that the contents of crude protein and total phosphorus in corn and soybean increased after extrusion,and the contents of fat,solubility of protein(P < 0.05)and heat sensitive protein(P < 0.05)decreased.The content of phytate phosphorus in corn were reduced significantly after extruded processing(P < 0.05),and the same trend was shown on the content of phytate phosphorus in soybean,but not significant(P >0.05).(2)Effects of extrusion processing on the nutritional quality of flaxseedFlaxseeds were extruded at the conditions of different initial moisture(30%,35%,40%,and 45%),expansion temperature(100℃,110 ℃,120℃,and 130℃),screw speed(120,140,160 and 180 r/min)and feeding rate(10,14,18 and 22 Hz)with four factors orthogonal design,and the detoxification rate,fatty acid,heat-sensitive protein,and crude protein digestibility of expansion flaxseed were analyzed.The results show that after extrusion,the digestibility of crude protein in vitro and detoxification of cyanogenic glycosides increased,but the contents of crude protein and heat-sensitive protein decreased significantly,and there were no effects on the composition of fatty acids.The initial moisture of feed ingredients was the main factor for the digestibility of crude protein,and crude protein content decreased significantly with the increasing of moisture,and the digestibility of crude protein decreased firstly and then increased.Expansion temperature was the main factor of sensitive protein,detoxification rate and fat content,the detoxification rate of flaxseed was increased significantly,and the contents of heat sensitive protein and crude fat had a downward trend with theincreasing puffing temperature.(3)Effect of extrusion on nutritional quality of corn germ meal,rapeseed meal and wheat middlingCorn germ meal,rapeseed meal and wheat middling were extruded with different expansion temperatures(120℃,140℃and160℃),screw speeds(130,150 and 170r/min)and feeding rate(12,14,and 16 Hz).A orthogonal tests design of three factors and three levels were performed to analyze the gelatinization degree,crude protein digestibility,and functional characteristics of feedstuffs after extrusion.The results show that extrusion technology affected the nutritional composition and physicochemical characterization of different feed ingredients.In our experiments,the expansion temperature was the main factor for the oil absorption of wheat middling,and the ability of oil absorption increased with increasing expansion temperature.The expansion temperature was also the main factor for the absorption ratio of water,starch gelatinization,heat sensitivity and protein digestibility in extrusion rapeseed meal,and all these items decreased with increasing temperature.For corn germ meal,the emulsifying property and starch gelatinization were affected by expansion temperature,and the degree of emulsifying and gelatinization increased with increasing temperature.The screw speed was the main factor for starch gelatinization degree,emulsification and protein digestibility.When the screw speed increased,the emulsification and protein digestibility increased firstly and then decreased,but there was a positive correlation between the screw speed and gelatinization.The feeding rate was main factor for the emulsification and emulsification stability of rapeseed meal,and they showed a weak trend with increasing feeding rate.The protein digestibility of extruded corn germ meal increased significantly with increasing feeding rate.