肉大鸡颗粒饲料的吸湿解吸平衡模型

为了研究成品饲料的吸湿解吸平衡规律，用GAB模型及其含温度变量的改良模型（mGAB, modified GAB）拟合静态法获得的肉大鸡颗粒料在15、25、35和45℃环境下，在11%至97%平衡相对湿度（即水活度0.11～0.97）范围内的吸湿平衡以及11%～75%（即水活度0.11～0.75）范围内的解吸平衡，得到优异的拟合精度。结果表明：随温度上升，饲料的平衡含水率下降，吸湿和解吸之间存在明显的滞后现象。用BET解吸模型计算的15～45℃范围内单层含水率为6.34%～5.39%（干基），并且随温度升高线性下降。以水活度0.65为安全贮存的临界点，对应于吸湿和解吸过程， 用改良GAB模型估计4个温度点的安全水分（干基）分别为13.09%和14.71%、12.92%和14.33%、12.74%和14.00%、12.56%和13.66%。研究结果为饲料的贮存和冷却过程规律研究提供了参考。

Models of moisture sorption isotherms for pelleted finishing broiler feed

To investigate the adsorption and desorption behavior of compound feeds, Guggenheim-Anderson-de Boer (GAB) equation and modified GAB were applied to fit the equilibrium moisture content (EMC) data of adsorption of a pelleted finishing broiler feed at equilibrium relative humidity (decimal, or water activity, Aw) from 0.11 to 0.97 and the desorption at water activities from 0.11 to 0.75 at 15℃, 25℃, 35℃ and 45℃, obtained by the conventional static gravimetric method. Both the equations gave excellent fitting goodness. EMC of the pellet feed reduced when temperature increased. Hysteresis existed between desorption and adsorption. Monolayer moisture content (Mm) from 15℃ to 45℃ estimated by Brunauer-Emmet-Teller (BET), fitting the desorption data, was between 6.34% and 5.39% (dry basis). The Mm reduced linearly with increasing temperature. Safe moisture content at the four temperatures, predicted by applying the modified GAB to adsorption and desorption data, was less than 13.09% and 14.71%, 12.92% and 14.33%, 12.74% and 14.00%, 12.56% and 13.66% (dry basis), respectively at Aw=0.65 as the critical point. The results give a reference for the feeds storage and cooling process.