Effect of solar collector drying on the nutritional properties of Çakıldak hazelnut

Abstract

This study investigated the effects of drying hazelnut in shell with husk samples from the ‘Çakıldak’ cultivar (Corylus avellana) using hot air heated by solar panels at different speeds (3.0 m s-1, 4.0 m s-1, 5.0 m s-1) on hazelnut properties. The hazelnuts were dried and their drying curve was determined by measuring their mass losses at regular intervals. Additionally, the total phenolics, DPPH radical scavenging activity, FRAP, free fatty acidity, peroxide value, and moisture content. For comparison, some of the samples were dried in the sun. The drying rate increased as the air speed increased and hazelnut samples dried the fastest at 5.0 m s-1 air speed. As a result of drying treatments, the total phenolic content ranged from 264.11 to 376.91 mg GAE 100 g-1, while the free fatty acidity ranged from 0.337% to 0.374%. The DPPH value ranged from 1.64 to 2.72 µg TE mg-1, and the FRAP value ranged from 1.23 to 2.29 µg TE g-1. The peroxide value ranged from 1.87 to 4.24 meq O2 kg-1, and the moisture content ranged from 3.43% to 5.18%. The hazelnut samples dried with an air speed of 3.0 m s-1 had the highest total phenolics, DPPH and FRAP values, as well as the lowest free fatty acidity and peroxide value. These values were statistically significantly different (p<0.05) from those of the sun-dried hazelnut samples. The study found that drying with a solar collector was more effective in preserving fruit quality. Additionally, the drying process was significantly impacted by different flow rates.