Role of enthalpy and entropy in moisture sorption behavior of pineapple pulp powder produced by different drying methods

详细信息    查看全文

• 作者：Juliane Viganó ; ^a ; ^{vanianic@ibilce.unesp.br} ; Ebner Azuara^b ; Vâ ; nia R.N. Telis^a ; Cesar I. Beristain^b ; Maribel Jim&eacute ; nez^b ; Javier Telis-Romero^a
• 关键词：Pineapple pulp powder ; Drying methods ; Water activity ; Sorption isotherms ; Thermodynamic properties
• 刊名：Thermochimica Acta
• 出版年：2012
• 出版时间：20 January, 2012
• 年：2012
• 卷：528
• 期：Complete
• 页码：63-71
• 全文大小：1008 K

文摘

Sorption mechanisms of pineapple powders produced by vibro-fluidized drying (VFD), spray drying (SD), freeze drying (FD) or vacuum drying (VD) were interpreted through enthalpy/entropy variations with respect to equilibrium moisture content (EMC) at 20, 30, 40 and 50 ¡ãC and water activity (a_w) between 0.059 and 0.907. Powders from SD and VFD were more hygroscopic and integral properties indicated higher stability at changing a_w compared to powders from VD and FD. Powders showed an enthalpy driven zone with equal isokinetic temperature (T_B1 = 499.0 ¡À 4.8 K) due to their same composition, and an entropy controlled zone with different isokinetic temperature, T_B2 (VD: 116.0 ¡À 40.6 K; FD: 118.3 ¡À 24.1 K; SD: 95.8 ¡À 23.4 K; VFD: 81.8 ¡À 6.3 K), caused by different microstructures resulting from different drying methods. Powders from SD and VFD presented larger entropic zones that shifted the minimum integral entropy to higher a_w, improving storage stability.