Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.

Copyright © Wydawnictwo Akademii Rolniczej we Wroclawiu, ISSN 1505-0297

Góral D. 2008. THE EFFECT OF DIFFERENT TECHNIQUES OF FREEZING AND DEFROSTING ON THE QUALITY OF SPICE VEGETABLES AFTER A LONG-TERM FREEZER STORAGE, EJPAU 11(1), #01.
Available Online: http://www.ejpau.media.pl/volume11/issue1/abs-01.html

ABSTRACT

The purpose of the paper was to study the effect of the conditions of freezing and defrosting of spice vegetables on selected determinants of their quality considering the freezer storage. The studies were conducted on carrot, parsley and chive. The studied raw materials were frozen (sample weight 0.5 kg): using the method of impingement (air temperature -20°C), in a freezer (temperature -30°C) and in an ultrakryostat (temperature -70°C). Freezing in a freezer and an ultrakryostat was continued until the temperature of -20°C was reached in the thermal centre of samples. After freezing, the raw materials were stored at the temperature of -20°C for the period of three months. Defrosting was continued until the temperature of 10°C was reached in the thermal centre of the sample: in the conditions of free convention in the air, by the method of revered fluidization, and in a water bath, keeping constant temperature of the environment of 15°C. The analysis was made of the kinetics of the processes, losses of the weight of samples, and an organoleptic evaluation was made of the samples after freezer storage and defrosting. During the storage, on average every 18 days the weight and the general state of the samples were examined comparing them with the samples of fresh raw materials. The lowest weight losses of carrot in freezing (2.35%) were caused by the air chilling method, while in case of parsley it was reversed fluidization. In case of chive no change of the weight after freezing and after defrosting was observed. Carrot weight losses after defrosting were the lowest (1.59%) among the samples frozen and defrosted by impingement method. The lowest losses of the weight of parsley samples (0.04%) were caused by freezing with air chilling method and defrosting in a water bath. Vegetables frozen by the method of reversed fluidization, stored and defrosted in the air in the conditions of free convention received the highest scores in the organoleptic test and hence their quality was only slightly changed in comparison with that of the fresh state. The condition of obtaining such quality of the examined vegetables is the period of the frozen storage which should not exceed 2.5 months at the temperature of -20°C.

Key words: frozen vegetables, spices, methods of freezing and defrosting, quality.

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Dariusz Góral
Department of Refrigeration and Food Industry Energetics, University of Life Sciences in Lublin, Poland
44 Doświadczalna
20-280 Lublin
Poland
Phone +48 81 4610061
email: dariusz.goral@up.lublin.pl

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