Characterization of Apple Surface Wax Layer by Active Thermography

Rosario Morello, Claudio De Capua

Abstract

The present paper reports the preliminary results of a study carried out to characterize the thermal response of apple surface wax layer. The experimentation has been performed on three different cultivars of apple (Golden delicious, Fuji and Red delicious). The present study is part of a research project which final aim is to reproduce artificially bio-wax films in order to cover and protect fruits during their life cycle from the tree to the table. Wax is a natural substance which covers the surface of some species of fruits such as the apples. This wax layer protects the fruit against parasites, atmospheric agents, thermal excursions, moisture loss, mechanical damage and microbiological infections. These singular features are object of studies and research activities. Consequently, an interesting challenge of researchers and agronomists is to develop new synthetic substances obtained by natural extracts or essences. <BR />In the proposed application case, the active thermography has been used in order to study the thermal response of the three apple varieties after a cooling process inside a climatic chamber. The thermographic images have been recorded during the heating process from 5 °C to 27 °C for 132 minutes. Consequently, the three heating rates have been compared. In this experimentation, the Fuji and Red apples have showed a slower heating rate due to the thicker wax layer. The emissivity has been measured for each apple and the whole experimentation has been carried under controlled environmental conditions to assure the repeatability and reproducibility of the experiment. <BR />The results have allowed to define the main thermal features and characteristics of the wax layer for future investigation.

Keywords

biological agriculture, apple wax, active thermography, emissivity, thermal response analysis, infrared thermal imaging

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DOI

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IMEKO TC

TC19 - Environmental Measurements

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