Influence of Osmodehydration Pretreatment and Combined Drying Method on the Bioactive Potential of Sour Cherry Fruits

Paulina Nowicka,Aneta Wojdyło,Adam Figiel,Krzysztof Lech

doi:10.1007/s11947-014-1447-y

Paulina Nowicka, Aneta Wojdyło + Show 2 more

Open Access

https://doi.org/10.1007/s11947-014-1447-y

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Abstract

The aim of this study was to determine the effect of osmotic dehydration (OD) time in apple concentrate on dehy- dration kinetics and quality parameters (polyphenol content and antioxidant activity) of sour cherries before further processing. Additionally, the study was focused on the effects of combined drying (convective drying+vacuum-microwave finish drying (CD-VMFD)) applied to fresh and osmodehydrated sour cherries in respect to drying kinetics, including the temperature evolution of dried material with time, as well as on quality factors of the finished product. Analyses were conducted for four kinds of sour cherries: frozen with stone (FS), frozen without stone (FW), thawed with stone (TS), and thawed without stone (TW), which were osmodehydrated for 180 min in the same operating conditions. The study revealed that the decrease of water loss to solid gain (WL/SG) ratio during OD of frozen sour cherries in apple concentrate associated with in- creased values of WL/SG was considerably enhanced by stone removal and the process of thawing. A logarithmic model was proposed for overall description of drying kinetics of combined drying. While OD time was increasing, the drying constant was decreasing for CD and obtained the maximum value for VMFD at the optimal time of OD, which was associated with achieving the peak temperature of VMFD material. It was found that the best variant of pretreatment of sour cherries, to be used for OD in apple concentrate, was freezing the fruits without stones. These fruits were characterized by a high content of polyphenols, high antioxidant activity, and the largest WL/SG ratio during OD process. It was also stated that the optimal method for sour cherry drying was the combined method consisting of OD (120 min) followed by CD (90 min) and VMFD, while maintaining the initial parameters.

Highlights

Sour cherry (Prunus cerasus L.) is one of the most attractive fruits in terms of nutritional value and sensory properties
The kinetics of osmotic dehydration (OD) depicting an increase of water loss (WL) and solid gain (SG) for different types of sour cherries dehydrated for 180 min in the osmotic solution prepared from the concentrated apple juice is shown in Figs. 1 and 2, respectively
The course of WL curves indicates that OD of fruits without stones (FW, thawed without stone (TW)) takes place at higher rates compared with OD of fruits with stones (FS, thawed with stone (TS)), which was expected assuming that the peal of sour cherries acts as a barrier to mass exchange during OD

Summary

Introduction

Sour cherry (Prunus cerasus L.) is one of the most attractive fruits in terms of nutritional value and sensory properties. It is characterized by intense red color and sour-sweet taste and contains many bioactive components beneficial for health, such as polyphenols or organic acids (Tarhan et al 2006). Anthocyanins present in sour cherry fruit, which impart the red color to the raw material, exhibit antioxidant, anti-inflammatory, antibacterial, and antidiabetic activities (Halvorsen et al 2002). Sour cherry is a seasonal fruit, and most processing technologies cause significant degradation of its bioactive compounds. New less invasive solutions are searched for that would ensure a similar nutritional value of processed cherry to that of the raw material

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