Comparative GLC‐MS Analysis of Phenolic Acids of Selected Tree Nuts

Abstract

Phenolic acids were extracted from the nutmeats and/or testae of pine nut, almond, filbert, American Chestnut, a hybrid American chestnut, Chinese chestnut, black walnut, butternut and shagbark hickory and analyzed as their methyl esters/trimethylsilyl derivatives by GLC-MS. Both qualitative and quantitative differences were observed among samples in the acids present with gallic acid being predominant except in pine nut, almond and filbert. Caffeic was the predominant acid in pine nut; protocatechuic acid was predominant in almond and filbert. Phenolic acids isolated and identified were p-hydroxybenzoic, p-hydroxyphenylacetic, vanillic, protocatechuic, syringic, gallic, caffeic and ferulic acids.

Walnuts (Juglans regia L): proximate composition, protein solubility, protein amino acid composition and proteinin vitro digestibility

“…The walnut globulin fraction, second to glutelin, contributed 17.6% of the total solubilised protein, followed by albumin (6.8%) and prolamin (5.5%). Since walnuts contain appreciable amounts of phenolic compounds that are soluble in aqueous solvents, 33 it is possible that the solubilised phenolic compounds may bind with walnut proteins. Such binding of phenolic compounds in turn may make normally soluble proteins less soluble (or insoluble) in water or dilute salt solutions.…”

Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects – A review

“…Amongst the identified phenolic acids, p-coumaric 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 (Alasalvar et al, 2006(Alasalvar et al, , 2009. However, in a previous study, protocatechuic acid was reported to be the predominant phenolic acid in testa (skin) of hazelnut (Senter, Horvat, & Forbus, 1983). Amaral et al (2005) identified and quantified four phenolic acids, namely, 3-caffeoylquinic acid, 5-caffeoylquinic acid, caffeoyltartaric acid, and p-coumaroyltartaric acid, in hazelnut leaves from 10 different cultivars grown in Portugal.…”

Phenolic compounds and antioxidant activity of Brazil nut (Bertholletia excelsa)

“…Among the identified phenolic acids, p-coumaric acid was most abundant in hazelnut kernel, hazelnut green leafy cover, and hazelnut tree leaves, 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. Senter et al (1983) compared phenolic acids of nine edible tree nuts produced in the United States. The extracts from the nut samples showed great diversity in the phenolic acids present.…”