The Effect Of Different Processing Technology On Processing Quality Of Hard Pellet

In this paper,we studied the moisture changes during the feed processing of grinding,conditioning,pelleting and cooling.We discussed the effects of different processing techniques on moisture,hardness of pellet,percentage of powdered pellets,starch gelatinization,thermosensible protein and crude protein digestibility in vitro of hard pellet.The results will provide experience for some researchers and feed enterprises.(1)The effect of grinding process on moisture,starch gelatinization and thermosensible protein of feed ingredientsThe trial was a single factor design,4 kinds of feed ingredients(corn,soybean meal,cottonseed meal and DDGS)were applied in the experiments,with 5 kinds of sieve apertures(0.4,0.6,0.8,1.0 and 1.5 mm)and 5 grinding time(60,90,120,150 and 180 s).The four kinds feed ingredients were grinded to investigate the variety of the moisture.The results showed that the loss of moisture in corn,soybean meal and cottonseed meal were increased with the grinding time.The moisture loss in corn was affected significantly by grinding time with five kinds of grinding particle size(P < 0.01).With the increasing of grinding particle size,the moisture in corn,soybean meal,cottonseed meal and DDGS were increased gradually,and showing extremely significant difference(P < 0.01).The results indicated that the linear correlativity between grinding particle size and moisture content were very prominent.The starch gelatinization of corn and formula feed were increased significantly with the reduction of grinding particle size(P < 0.01);the moisture in corn and formula feed were showed correlativity significantly with starch gelatinization(P < 0.05);the moisture in soybean meal was showed extremely correlativity significantly with the thermosensible protein(P < 0.01).(2)The effect of conditioning,pelleting and cooling process on processing quality of hard pelletThree factors and three levels orthogonal designs were adopted in the experiment.The broiler corn-soybean formula feed was used in the experiment.Three levels of initial moisture content(10%,12% and 14%)and three conditioning time(30,45 and 60 s)were set with three kinds die mold(length/diameter ratio and diameter of die hole are 22/17,2.0 mm;35/26,3.0 mm and 35/12,3.0 mm).The pellet moisture and processing quality index were measured after cooling by air drying at normal temperature(0,2,15,27,42 and 60 h).The results showed that the effects of conditioning,pelleting and cooling process on feed moisture were significantly different(P < 0.01).The effect of cooling time on the hardness of the feed was extremely significant(P < 0.01).The effects of conditioning and pelleting on the thermosensible protein and starch gelatinization of the feed were extremely significant(P < 0.01).The moisture of feed before conditioning is the key factor on affecting the moisture,thermosensible protein and the crude protein digestibility of pellet feed in vitro.The higher the moisture content of the powder before conditioning,the higher the crude protein digestibility in vitro of the pellet feed.The ring mold is the main factor affecting the hardness,pulverization rate and starch gelatinization degree of the pellet feed,and the larger the length/diameter ratio of the ring mold,the smaller the pore size of the ring mold,the greater hardness and the smaller pulverization rate of the pellet feed.