Adsorption characteristics of a ready-made mixture of linseed and dried fruit

¹ Department of Process Engineering, Technical Faculty, University of Food Technologies, Plovdiv, Bulgaria
² Department of Mechanical and Instrument Engineering, Faculty of Mechanical Engineering, Branch Plovdiv of Technical University, Sofia, Bulgaria
³ Language Training Center, University of Food Technologies, Plovdiv, Bulgaria

^* Corresponding author: aldurakova@abv.bg

Abstract

Sorption characteristics are an integral part of scientific research on new products since they provide data on the means of processing, transportation, and storage of food products. The present study focuses on the adsorption characteristics of a ready-made mixture of golden linseed – 46%; brown linseed – 25%; granulated plums – 9% and granulated dates – 8% which are organic farming ingredients. The experiment was conducted at temperatures of 10°C, 25°C and 40°C and water activities in the 11.2% -86.8% range. The results demonstrate that at constant water activities the increase in temperature is coupled by a decrease in equilibrium moisture content. The sorption isotherms obtained belong to Type III, typical of food products, according to the classification of Brunauer et al. For the description of adsorption isotherms, we recommend Oswin’s modified three-parameter model. Via the linearization of Brunauer-Emmett-Teller’s model, we calculated the values of the monolayer moisture content (MMC) of the mixture for the three temperatures: 10ºС – 4.85% d.m.; 25ºС – 3.92% d.m. and 40ºС – 3.34% d.m. with control points for water activity of a_w < 0.5.