Hazelnut hard shell

Tree Nuts Composition, Phytochemicals, and Health Effects Hazelnut hard shell Hazelnut kernel (with skin)... 

Five soluble phenolic acids (free and esterifled), one of which is a hydroxylated derivative of benzoic acid (gallic acid) and four are cinnamic acid derivatives (caffeic, p-coumaric, ferulic, and sinapic acids), have been studied and tentatively identified in ethanolic extracts of hazelnut kernel and hazelnut by-products (Table 13.2) [31]. The order of total phenolic acid concentration was as follows hazelnut hard shell > hazelnut green leafy cover > hazelnut tree leaf > hazelnut skin > hazelnut kernel. Different phenolic acids predominate in each plant part examined. Among the identified phenolic acids, p-conmaric acid was most abundant in hazelnut kernel, hazelnut green leafy cover, and hazelnut tree leaf, whereas gallic acid was most abundant in hazelnut skin and hazelnut hard shell, possibly implying the presence and perhaps the dominance of tannins in the latter samples (Table 13.2). The same number, but different concentration, of phenolic acids have also been reported in hazelnnt kernel and hazelnut green leafy cover [30]. 

High tannin content in hazelnut by-product extract (skin and hard shell) was reported by Contini et al. [ 100]. Total tannins represented the principal fraction of the phenolic substances of the extracts, containing nearly 60%-65% of the total phenol [100]. As a general rule, the highest amount of total tannins was detected in the extracts with the highest amount of total phenols. Hence, the high antioxidant activity in hazelnut by-product extracts maybe due to these polyphenolic compounds since they are expected to have powerful antioxidant activity [100]. 

Small amounts of paclitaxel were also isolated from Turkish Tombul hazelnut tree leaf (0.05 J.g/g extract) and hard shell (0.08(tg/g extract). In addition to paclitaxel, 10 deacetyl baccatin III and cephalomannine (leaf and hard shell) and baccatin III (green leafy cover) were found in the extracts (Table 13.10). Taxanes were not detected in the extracts of hazelnut kernel and hazelnut skin from Turkish Tombul cultivar. 

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