Benedek Kerekes

• PhD, Habil, Prof.
• Head of Department at University of Nyíregyháza

A mezőgazdasági késztermékek előállításában a szárítás az egyik legjelentősebb technológiai költségtényező. A dehidrálási művelet kiadásait tekintve a karbantartás, az élőmunka igény mellett, igen meghatározó a felhasznált hőenergia költsége.A hazai szemestermény szárítógép-park összetételét vizsgálva, többsége rendkívül korszerűtlen berendezésekbő...

In Hungary there is a revolutionary new method, a joint application of an air-turbo refrigerator and sublimation drier. The complex equipment is suitable for production of an excellent quality dried food. The study shows the construction of the system and demonstrates some examination of the typical parameters, for example the drying curve, chemica...

Mid-infrared-assisted freeze drying (MIR-FD) of Jerusalem artichoke cubes were attempted and their performance (processing time, energy consumption, color, water activity, hardness and rehydration) was compared with single-stage freeze dried (FD, control) samples. Two mathematical models could be used to describe the drying curves. It was aimed to...

The dehydration tests were conducted at three drying methods to evaluate the drying curves and the energy uptake. Apple (Malus domestica L.) cubes were dried under different processing conditions, applying freeze-drying (FD) method, supplemented by hot air (HA) and infrared radiation drying (IR) techniques. The IR heating method produced a higher d...

In this study, the influences of various pre-treatments and combined drying (CD) on the drying kinetics and quality parameters of sour cherry were investigated. Prior to freeze drying (FD), sour cherry was pre-treated by blanching in boiling water (100 °C, 3 and 6 min), immersion in sugar solution (20% w/w, 10 and 20 min) and blanching (100 °C) in...

The drying methods tested were hot-air drying (HAD) and freeze-drying (FD), as well as a combination of blanching (100C, 1 min) prior to FD pre-drying and HAD finish drying. The effect of drying methods on moisture content, temperature, energy consumption, duration of drying, rehydration properties, color, texture and sensory were determined. Apple...

The importance of the study presented in this manuscript lies in its being the first detailed analysis of the influence of the alkaline water pre-treatment on apples dehydrated by freeze-drying. The results obtained revealed a significant effect of this pre-treatment on the drying time and the quality of freeze-dried apple cubes determined by both...

The effect of freezing rate on the quality of dried Jonagold and Idared was studied. Apple slices underwent various pre-treatments, i.e. freezing in household freezer (freezing rate: 0,5 °C/min), contact plate freezing (2 °C/min) and vacuum-freezing (3 °C/min). The quality of the freeze dried product was then evaluated in terms of water activity, h...

The aim of the research work was to determine the effects of four different pre-treatments on the freeze drying behaviour of apple and dried product texture. Fresh apple (Malus domestica) of Jonathan variety was used as experimental material. The texture of apple (fresh and freeze dried) was determined by compressive test. The pre-treatments includ...

In this study, the influences of the thermal and chemical pre-treatment methods on the physical properties and drying time of potato and carrot cubes were investigated. The vegetables cubes were dried in a freeze drier. The moisture content, water activity, hardness and rehydration capacity were determined. Improvement of freeze dried food quality...

The effect of alkaline-ionized water (pH 8,5-9) dipping pre-treatment on drying kinetics of apple varieties ('Idared', 'Golden') under vacuum freeze-drying conditions has been studied. It was observed that the pre-treatment affected the drying time. The drying time was shorter for treated with alkaline-ionized water solution compared to the untreat...

The effect of alkaline-ionized water (pH 8,5-9) dipping pre-treatment on drying kinetics of apple varieties ('Idared', 'Golden') under vacuum freeze-drying conditions has been studied. It was observed that the pre-treatment affected the drying time. The drying time was shorter for treated with alkaline-ionized water solution compared to the untreat...

The effect of alkaline-ionized water (pH 8,5-9) dipping pre-treatment on drying kinetics of apple varieties ('Idared', 'Golden') under vacuum freeze-drying conditions has been studied. It was observed that the pre-treatment affected the drying time. The drying time was shorter for treated with alkaline-ionized water solution compared to the untreat...

The effect of freezing rate on the quality of dried Jonagold and Idared (Malus domestica Borkh.) was studied. Apple slices underwent various pre-treatments, i.e. freezing in household freezer (freezing speed/rate: 0,5◦C/min), contact plate freezing (2◦C/min) and vacuumfreezing (3◦C/min). The quality of the freeze-dried product was then evaluated in...

The sensory investigation is essential for evaluation of the food products. The effects of hot-air drying, vacuum drying and vacuum freeze-drying on sensory parameters of apple were studied. The quality characteristics determined were appearance, smell/flavor, taste, texture, color and overall acceptability. The sensory evaluation of dried apple (J...

REZUMAT. Cercetarea se concentrează pe analiza componenței chimice a uleiului esenţial de lămâie. Uleiul esenţial din frunze a fost obţinut prin extracţie. Componentele chimice ale uleiului esenţial de lămâie au fost analizate cu un GC capilar şi GC/MS, 8 substanţe fiind identificate. Calitatea produsului final depinde, în mare măsură, de operaţia...

Drying is one of the primary processes involved in the manufacture of herbs, which themselves come in the form of stems, leaves, and roots. The quality of the final product depends on the procedure used and drying method. This article presents the results pertaining to the drying behavior of spearmint in both hot air drying and freeze drying condit...

REZUMAT. Cercetarea se concentrează pe analiza componenței chimice a uleiului esenţial de lămâie. Uleiul esenţial din frunze a fost obţinut prin extracţie. Componentele chimice ale uleiului esenţial de lămâie au fost analizate cu un GC capilar şi GC/MS, 8 substanţe fiind identificate. Calitatea produsului final depinde, în mare măsură, de operaţia...

Spearmint was dried using a freeze drier and conventional hot air drier. The effect of the drying method on the content of volatiles and dehydration kinetics of the herb was evaluated. The volatile constituents of herb were isolated by extraction and analysed by gas chromatography. A total of 9 compounds were identified in spearmint. It was found t...

The purpose of the investigation was to determine the moisture relationship experimentally in the drying of tobacco leaves. A simple experimental model was applied for calculating the moisture ratio. The measurements carried out in a 'climate box', studying different tobacco leaves. Two measuring cycles were carried out during the latest research w...

In the past years many practical trials were carried out for answering of some important technological and technical questions in the field of tobacco curing.

Analytical and numeric models have been created for writing surface heat-production and heat transmitting parameters equation gives a possibility for calculating some typical physical parameters.

The laboratory equipments are important in elaboration of technologies in freeze drying, for research of the product quality, amelioration, moreover determination of transport properties. Our department has a laboratory vacuum freeze drying equipment (Armfield FT 33). We can register all the data during the procedure. It's important to analyze this...