| Four experiments were conducted to investigate the nutritional and physicochemical properties of soybean meal powder with different particle size by the methods and technique of mechano-physics, spectroscopic analysis, electrophoresis and animal feeding trials. The nutritional and physicochemical characteristics of micronized soybean meal were especially studied, which could provide basal and oriented experimental support to the development of artifactitious nutritional potential in protein feedstuff such as soybean meal.Exp.1Effect of the process of micronization on basal physical properties of soybean meal.The trail was conducted to study particle size and its distribution, specific surface area, bulk density, tap density, repose angle, slide angle and water-or oil-absorbing property of soybean meal powder self-produced with different objective average particle sizes (800,400,100,50,25,10,5.0,2.5,1.0μm). The results were as follows.The soybean meal powder had more specific surface area with less particle size, and that the specific surface area of soybean meal powder was significantly negative relation with the particle size as exponential function (y=19.082x-1.0499, r2=0.9669, p=0.003, y is specific surface area, x is particle size). The Particle size of soybean meal powder was from100to10μm, the specific surface area of the sample with10μm particle size was2444.4%bigger than that of the. sample100μm particle size. And the particle size from10to1μm, the specific surface area of the sample with1μm particle size was442.8%bigger than that of the.sample10μm particle size.Bulk density and tap density of the soybean meal powder were significantly reduced when the particle size was in the micro-meter range from0.1to30μm, which were significantly positive relationship with the particle size, respectively (y1=71.283Ln(x)+173.5<r2=0.9311p=0.032> and y2=81.017Ln(x)+868.3<r2=0.9413, p=0.017>, y1is bulk density, y2is tap density, x is particle size). Repose angle and slide angle of soybean meal powder had prominent increase as specificflow function (y1=48.039x-0.066<r2=0.9715, p=0.007> and y2=57.211x-0.0821<r2=0.9541, p=0.047>, y1is repose angle, y2is slide angle, x is particle size), and the fluidity of powder was markedly reduced.Water-or oil-absorbing properties and water-soluble substance content of the soybean meal powder were significantly enhanced, when the particle size was in the micro-meter range from0.1to30μm, as exponential functions (y1=2.3662x-0.0406<r2=0.9751, p=0.027>; y2=2.9302x-0.0879<r2=0.973, p=0.005> and y3=61.406x-0.2032<r2=0.969, p=0.013>. y1is water-absorbing ratio, y2is oil-absorbing ratio, y3is water-soluble substance content, x is particle size),The colour of soybean meal powder in the micro-meter range from0.1to30μm was lighter than that of soybean meal powder ground in conventional condition, and the whiteness was in negative correlation to particle size as exponential function (y=89.768x-0.1493, r2=0.9661, p=0.008, y is the whiteness, x is particle size). And soybean meal powder in the micro-meter range from0.1to30μm had no effects on water activity of it.Exp2Studies on mechanochemical effects in the micronizing process of soybean mealThe experiment was conducted to investigate the mechanochemical effects in the ultrafine process of soybean meal by the methods of fluorescence analysis, differential thermal analysis and ultra-weak photon emission, with different micro-meter-grade soybean meal powder and general ground soybean meal as research objects. The degradation of advanced protein structure, and the intensity of radical ion effect were investigated. The results were as follows.There was the higher content of-SH with smaller particle size of soybean meal powder, and the content of-SH was increased34.1%in soybean meal powder of D501.09μm than D50635.13μm. The breakage of oelophilic group was enhanced36.37%for D501.09μm soybean meal powder. Three dimensional structure of protein was destroyed at a certain extent, and globulin was partly denaturation. The denatural temperature of D501.09μm soybean meal powder was higher10.65℃than that of D50635.13μm soybean meal powder. The ultra-weak photon emission analysis proved that the content of radical ion was improved.Exp.3Effect of the micronizing process on digestibility and enzyme hydrolyzed characteristics of soybean meal powder in vitroIn this trail, the digestibility in vitro and the enzyme hydrolyzed characteristics of soybean meal powder with different particle size were studied by the methods in vitro, the general ground soybean meal as control. The results indicated that the pepsin digestibility of micronized soybean meal was48.0%higher with26.65percents than that of the control. And the pepsin-trypsin digestibility of micronized soybean meal was enhanced42.2%with26.86percents than that of the control. The very superfine soybean meal improved the pepsin digestibility with higher efficiency than the control. The digestible velocity of pepsin in the very superfine soybean meal was higher than that in control.Exp.4Effects of very superfine soybean meal on the productivity and nutrients digestibilities of pigletsA total of64piglets (Duroc×Landrace×Yordshire),26-30-day age and7.9±0.7kg body weight (BW), were selected the day of weaning. Piglets were ear-tagged, weighed and allotted to the experimental units according to sex and BW. There were four treatments and four replicates of four piglets per treatment. Effects of soybean meal with four particle sizes of750,150,30,6μ m on the productivity and nutrients digestibilities of piglets were studied,750μ m soybean meal as control. The results showed that The ADG of weaned piglets fed with a ration with very ultrafine soybean meal powder was markedly increased (p<0.05), the ADFI was enhanced (p>0.05), F/G was improved significantly (p<0.05), and the diarrhoea incidence was reduced markedly (p<0.01). The micronized soybean meal powder increased the coefficient of total tract and ilea apparent digestibility of dietary nitrogen, EAA, NEAA, and P, but the coefficient of total tract and ilea apparent digestibility of dietary GE and O.M were not affected.Therefore, The agreement of physicochemical properties as nutrients of soybean meal after micronization was improved significantly. The mechanochemica effects in the micronizing processs of soybean meal have functions of reducing the negative effects of macromolecule protein and improving the efficiency of nutrients. |
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