Nowadays, hazelnut tree leaf, a byproduct of hazelnut harvesting, is seen as a potential source of natural
antioxidants. In this study, the phenolic composition of 93 samples (19 cultivars collected along 3 crop
years in 2 geographical locations) was determined to evaluate the influence of genetic and edaphoclimatic
factors. Besides, a seasonal pattern variation study was performed, comprising the screening
(from May to September) of the phenolic composition of four cultivars under the same agricultural,
geographical and climatic conditions. Hazelnut leaf showed to be a good source of total phenolics since
its content ranged from 2.5 to 30.5 g/kg. A seasonal pattern was observed consisting of an increase of
the total phenolic content from May to July, a considerable decrease in August and a new increase in
September. In all cultivars, the highest content of phenolics was achieved in July. Multivariated statistical
analysis suggests that phenolics content in hazelnut leaves is mainly affected by the factor “crop year”,
although genetic factors can also exert a moderate influence.
