Microwave Irradiation for Dry-Roasting of Hazelnuts and Evaluation of Microwave Treatment on Hazelnuts Peeling and Fatty Acid Oxidation

Abstract

European hazelnut is an important nut crop in Italy, where about 121,750 tons of in-shell nuts are produced every year. Roasting is the most important practice for hazelnut preservation and commonly is carried out in commercial electrical ovens at 120-160°C for 10-20 min. This needful practice is time and energy expensive, so the development of new processing methods is required to reduce processing costs and to obtain top quality roasted nuts. The aim of this study was to develop a simple microwave treatment for hazelnuts peeling and roasting.With this aim, some physical (colour, temperature, moisture) and chemical (taste, lipoxygenase activity, fatty acids, vitamins, sensory attributes) features of inshell nuts and kernels of three Italian hazelnut varieties (Tonda di Giffoni, Tonda Romana and Nocchione) after conventional oven or microwave roasting were evaluated.Results showed that microwave roasting of kernels for 450 s gave a higher peeling score than the conventional oven treatment. This paralleled with better colour and taste scores for microwaved roasted kernels. Furthermore, a 360-450 s microwave roasting was able to inactivate almost completely lipoxygenases, avoiding adverse effects on fatty acids hydroperoxides and PUFA content. A shorter microwave treatment (360 s) was enough to obtain good peeling and sensory scores of inshell hazelnuts.Taken together our results indicated that microwave technology can be successfully applied to both kernels and inshell hazelnuts to obtain suitable peeling and high quality roasted nuts.

The effect of heat treatment on phenolic compounds and fatty acid composition of Brazilian nut and hazelnut

“…Roasting involves a number of physico-chemical changes including dehydration and chemical reactions (Ciarmiello et al 2013). According to results, fatty acid composition and phenolic compounds were affected by conventional oven and microwave heating.…”

“…Turkey, especially coast of the Black Sea region, is the most important producer of hazelnut, contributing about 70.3% of the total world production (Alasalvar et al 2010;Jakopic et al 2011). The quality and fatty acid composition of hazelnut can be affected by climatic conditions, variety, location and cultural practices (Alasalvar et al 2010;Ciarmiello et al 2013). Hazelnut are rich source of essentials minerals, sterols, fatty acids, free phenolic acids, organic acids and phenolic compounds (gallic acid etc.)…”

“…Hazelnut are rich source of essentials minerals, sterols, fatty acids, free phenolic acids, organic acids and phenolic compounds (gallic acid etc.) (Cristofori et al 2008;Alasalvar et al 2010;Jakopic et al 2011;Ciarmiello et al 2013). Due to their high polyphenol contents, hazelnuts are recognised as a good source of natural antioxidants (Solar and Stampar 2011).…”

Static Hot Air and Infrared Rays Roasting are Efficient Methods for Aflatoxin Decontamination on Hazelnuts

“…Hot air roasting is a convective heat transfer process, and the temperature rises as a function of heat transfer. As the nut temperature approaches 120 °C, the rate of temperature increase slows and the moisture evaporation accelerates [ 27 ]. In the present study, static hot air treatment generally induced a higher detoxification with increasing exposure time.…”

Influence of microwave treatment on quality parameters of snacks food. Impact issuees

“…In comments, the evaluators described microwave-roasted hazelnuts as "typical for good-quality chocolates with nuts". Ciarmiello et al studies compared microwave-roasted hazelnuts treated with exposures times of 240, 300, 360, 4 indicated that the best taste score was recorded with 450 s and 600 s microwave treatment [28].…”