Effect of Variety on Rehydration Characteristics of Dried Apples

Abstract

The effect of dried apple varieties on their rehydration characteristics was investigated. Four varieties of apples, Champion, Cortland, Grey Reinette and Ligol, were taken into consideration. Rehydration properties and color of apples were investigated. In order to examine the influence of apple variety on its rehydration properties, the process of rehydration was modeled. The model parameters obtained for investigated apple varieties were compared. Apple cubes were dried in a tunnel dryer (air temperature 60 °C and air velocity 2 m/s) and next rehydrated in distilled water at temperature: 20, 45 and 70 °C. Mass, dry matter mass, volume and color attributes of apples (raw, dried and rehydrated) were measured. The process of rehydration was modeled using empirical (Peleg and Weibull models) and theoretical (the Fick’s second law) models. Results of the analysis showed that the apple variety affects values of mass and volume increase, dry matter decrease and color of the rehydrated apple. Discussed parameters were also affected by rehydration temperature. Fick’s second law model can be considered as the most appropriate. Apple variety and rehydration temperature influenced the values of the model’s constants. Obtained values enabled attempts of the explanation of the rehydration course. It can be stated that apple var. Champion showed a greater rate of water absorption during the entire process of rehydration than other investigated varieties.

Effects of cutting and drying method (vacuum freezing, catalytic infrared, and hot air drying) on rehydration kinetics and physicochemical characteristics of ginger (Zingiber officinale Roscoe)

“…The fitting of the empirical models was carried out with the following assumptions: water temperature remains constant during the rehydration process, and the sample has uniform initial moisture content before rehydration (10 ± 1.2%). The various empirical models used were: the Peleg model, first‐order dynamic model, exponential model, and polynomial model are in shown Equations (2)–(5), respectively (García‐Segovia et al., 2011; Górnicki et al., 2020; Kumar et al., 2011): $$\begin{equation}{\rm{RR}}\ = {W}_0\ + \frac{1}{{{k}_1 + {k}_2t}}\end{equation}$$ $$\begin{equation}{\rm{RR}}\ = {W}_{\rm{e}}\ + \left( {{W}_0 - {W}_{\rm{e}}} \right){\rm{exp}}\left( { - {k}_3t} \right)\end{equation}$$ $$\begin{equation}{\rm{RR}}\ = {W}_{\rm{e}}\ \left[ {1 - \exp \left( { - {k}_4t} \right)} \right]\end{equation}$$ $$\begin{equation}{\rm{RR}}\ = \ a{t}^2 + bt + c\end{equation}$$where W e is the water content at equilibrium (dry basis); W 0 is the initial water content (dry basis); t is rehydration time, min; k 1 , k 2 , k 3 , k 4 , a , b , and c are constants.…”

“…The fitting of the empirical models was carried out with the following assumptions: water temperature remains constant during the rehydration process, and the sample has uniform initial moisture content before rehydration (10 ± 1.2%). The various empirical models used were: the Peleg model, first-order dynamic model, exponential model, and polynomial model are in shown Equations ( 2)-( 5), respectively (García-Segovia et al, 2011;Górnicki et al, 2020;Kumar et al, 2011):…”

Drying and rehydration kinetics of peeled and unpeeled green apple slices (Granny Smith cv)

“…The study of the rehydration kinetics of dry vegetal tissues is composed of three simultaneous processes: water adsorption, swelling, and leaching of soluble compounds [31]. To model the rehydration kinetics of fruits and vegetables, the equation of Fick's second law and semiempirical equations based on it are generally used [32], in addition to Peleg and Weibull model, which have been used by several researchers [29,33].…”

Effect of Hot Air Drying Temperature on Drying Kinetics, Physico-Chemical Properties, and Energy Consumption of Culture Asparagus (Asparagus officinalis L.)

“…While water gain in the dried product occurs rapidly in the beginning of the rehydration process, the rehydration rate diminishes as the product moisture content approaches the equilibrium moisture content value [35]. Over the course of rehydration processing, below steps occur concurrently: absorption of liquid on the part of the dried foodstuff, swelling of the rehydrated product and filtering of the solutes (vitamin, mineral, sugar, acid) from the foodstuff to the rehydrating environment [36].…”