Freeze Drying and Animal Products Technology Section, Defence Food Research Laboratory, Siddharthanagar, Mysore, 570011 India.
J Food Sci Technol. 2014 Oct;51(10):2734-40. doi: 10.1007/s13197-012-0797-6. Epub 2012 Aug 10.
Moisture sorption isotherms of freeze dried whey-grape beverage powder were determined at 20, 30 and 40 °C. A gravimetric static method was used under 0.11-0.85 water activity range and the sorption isotherms were found to be Type II. Various mathematical models were fitted to experimental data and it was found that Peleg model suits best in describing the equilibrium moisture content-equilibrium relative humidity relationships of instant whey-grape beverage mix over the range of temperatures studied. The net isosteric heat of sorption varied between 5.22 and 1.12 KJ/mol at moisture level varying between 1 and 9 % db. At moisture content below 1 % (db) the isosteric heat of sorption increased sharply for freeze dried whey-grape beverage powder and value of 49.08 KJ/mol was estimated.
冷冻干燥乳清-葡萄饮料粉的吸湿等温线在 20、30 和 40°C 下确定。在 0.11-0.85 水活度范围内使用重量静态法，发现吸附等温线为 II 型。将各种数学模型拟合到实验数据上，发现 Peleg 模型最适合描述瞬时乳清-葡萄饮料混合物在研究温度范围内的平衡水分含量与平衡相对湿度的关系。在水分含量为 1%至 9%（干基）之间，吸附的净等焓变化在 5.22 和 1.12 KJ/mol 之间。在水分含量低于 1%（干基）时，冷冻干燥乳清-葡萄饮料粉的吸附等焓急剧增加，估计值为 49.08 KJ/mol。
