Sorption Isotherms and Net Isosteric Heat of Sorption for Plum Osmotically Pre-Treated With Trehalose and Sucrose Solutions

T. AKTAS¹, P. ULGER¹, F. DAGLIOGLU¹ and F. H. SAHIN^2
1 Namik Kemal University, Department of Biosystem Engineering, Agricultural Faculty, 59400, Tekirdag, Turkey
² Namik Kemal University, Department of Agricultural Machinery, Vocational School of Hayrabolu, 59400, Tekirdag, Turkey

Abstract

AKTAS, T., P. ULGER, F. DAGLIOGLU and F. H. SAHIN, 2014. Sorption isotherms and net isosteric heat of sorption for plum osmotically pre-treated with trehalose and sucrose solutions. Bulg. J. Agric. Sci., 20: 515-522

 

Net isosteric heat of sorption can be used to determine the energy requirements of drying processes. Trehalose pre-treatments have better effects on some quality properties such as colour, shrinkage and cell reconstruction of dried agricultural materials. In this study, changing of moisture sorption isotherms and net isosteric heat of sorption for plum were determined at 30, 40, 50, 60°C. Sorption isotherms were determined using standard static gravimetric method. The net isosteric heat was determined by the application of the Clausius-Clapeyron equation to obtained sorption isotherms. Plum samples were pretreated osmotically with trehalose and sucrose solutions with 20 and 50 Brix concentrations.

Key words: plum, sorption isotherms, net isosteric heat, osmotic treatment
Abbreviations: M - Equilibrium moisture content (Decimal, d.b.); N - number of experimental data; n - number of constant in models; RMSE - Root mean square error; EF - modelling efficiency; M₀ - mono-layer moisture content (d.b.); a_w - water activity; c, k, n - empirical parameters; C, K - empirical GAB parameters; q_st - net isosteric heat of sorption (kJmol^-1); Q_st - isosteric heat of sorption (kJmol^-1); R - universal gas constant (kJmol^-1K^-1); ΔH_vap - the heat of vaporisation (kJmol^-1 water); T - absolute temperature (K)
Subscripts: pre – predicted; exp – experimental

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