Właściwości sorpcyjne ciastek kruchych z mąką z ciecierzycy

Celem prac było wyznaczenie izoterm sorpcji pary wodnej na ciastkach kruchych, w których mąkę pszenną suplementowano mąką z ciecierzycy (20, 40, 60 i 80%). Zakres pracy obejmował analizę izoterm sorpcji wyznaczonych w środowisku o aktywności wody 0; 0,113; 0,225; 0,329; 0,438; 0,529; 0,648; 0,753. Ciastka zawierające w swoim składzie: mąkę pszenną (typ 550) suplementowaną mąką z ciecierzycy, tłuszcz cukierniczy, cukier puder, proszek do pieczenia oraz wodę wypiekano w warunkach laboratoryjnych w piecu elektrycznym, w temperaturze 190°C przez 15 minut. Do wyznaczenia izoterm sorpcji stosowano metodę statyczno-eksykatorową. Wszystkie pomiary prowadzono w temperaturze 25°C, w dwóch powtórzeniach. Izotermy adsorpcji pary wodnej opisano modelami matematycznymi: BET, GAB, Pelega oraz Lewickiego. Izotermy adsorpcji wody badanych ciastek kruchych miały kształt sigmoidalny i zgodnie z klasyfikacją Brunauera odpowiadały II typowi izoterm. Modele Peleg i BET najlepiej opisywały otrzymane izotermy wszystkich rodzajów ciastek.

The water activity and sorption properties of food have been considered as important physical properties in food processes. The knowledge of the course of water vapor adsorption isotherms give us a lot of valuable information about food structure. Isotherms allows to determine the sensitivity of product for moisture and degree of water adsorption. It is well known that biscuits with a water content higher than the relative humidity values correspondent to monolayer leads to adverse changes and consequently results in a quality loss. Because of modifications of the recipe composition we have to measure a sorption properties of new products to study the stability of this products during packaging and storage. The aim of this study was to determine sorption properties of short-dough biscuits, in which wheat flour was replaced by chickpea flour (20, 40, 60, 80%). The scope of this study included analysis of sorption isotherms, which were measured in the environment showing the following water activities: 0, 0.113, 0.225, 0.329, 0.438, 0.529, 0.648, 0.753.The analyzed material was composed of short-dough biscuits baked in laboratory conditions at 190°C by 15 minutes in an industrial electric oven. The biscuits were composed of the following ingredients: wheat flour (type 550), chickpea flour, shortening, powdered sugar, baking powder and water. The static-desiccators method was applied to determine the sorption isotherms. All measurements were performed at 25°C, in two replicates. The water vapor adsorption isotherms of the biscuits were determined using BET, GAB, Peleg and Lewicki mathematical models. It was found that the shape of water adsorption isotherms of short-dough biscuits were sigmoidal and were characterized by a II isotherm type according to the Brunauer’s classification. The Peleg and BET models were the best to describe the sorption isotherms of all biscuits. Modification of the formula of short-dough biscuits had influence on sorption properties of biscuits. At lower values of water activity (0–0.4) the highest differences in equilibrium water content of analyzed biscuits were observed. The short-dough biscuits with wheat flour were characterized by a higher values of equilibrium water content than the short-dough biscuits with chickpea flour.