A rapid and precise method for determining water content in nuts as a tool for determining their quality during storage

Abstract

This study was designed to examine impact of storage conditions on hazelnut quality and to develop a quick method for testing hazelnut moisture. The change of sample mass and water content were assessed by convection drying method and by means of a moisture analyzer—IR radiation. The samples were tested as: nuts, nut kernels, crumbled nut kernels, husk of nuts. They were stored in closed and open packages at 45% and 80% humidity and at constant temperature (23 °C). It has been observed that at the humidity of 45%, the hermetic packaging reduced hazelnut mass loss by 18%, and the hazelnut husk caused reduction of mass loss of the kernel by 5.5%. It was found that the best storage effects were obtained at a relative air humidity of 80% (i.e. change in hazelnut weight 2.18%, kernels 0.78%, shell 1.4%). At this moisture content, in comparison with the moisture content equal to 45%, a lower loss of hazelnut weight by 4.65%, kernel weight by 10.79%, shell weight by more than two times was found when the samples were stored without packaging. Water desorption from hazelnut stored under these conditions was reduced to 0.4% for packaged kernels and to 3% for unpackaged product. Determining the water content by the IR radiation method, compared to the standard method, took much less time, it took about 1 h. 5 min (approx. 6 times faster) with a measurement accuracy of 0.26%. Therefore this paper proves that the described method positively influences time restrictions especially when the duration of water content analysis is a key determinant. According to the authors, it can be implemented in both laboratory and industrial tests, saving time and acting immediately when the technological process requires support.