Chemical and nutritive characteristics of tree nut oils available in the U.S. market

Abstract

Tree nuts have become increasingly popular in the U.S. market due to their healthful fats and beneficial micronutrients and bioactives. The use of specialty tree nut oils has also been growing in popularity. As proper quality control measures are not currently in place, and published information on tree nut oils in the USDA National Nutrient Database for Standard Reference (SR28) is antiquated, an improved understanding of nut oil compositions could be of use to the industry and field. In this study, 20 commercially available brands of specialty tree nut oils, either imported or domestic, were analyzed to determine their contents of fatty acids, tocopherols (Ts), and phytosterols. While recent publications and the USDA Database confirm that γ‐T is the primary homolog endogenous to pecan oil, three of the four pecan oil samples tested were found to be most concentrated in α‐T. The T concentrations were also determined to be highly predictive of nut oil unsaturation (as summarized by calculated iodine values; = 0.913), with the concentration of δ‐T presenting the greatest numeric weight to the model. The compositional information presented in this paper provides more in‐depth information on commercially available specialty tree nut oils.Practical applications: The information reported provides a better understanding of important compositional factors within tree nut oils, which can be of benefit to those that either produce or utilize such oils. These understandings are important to nutritional considerations, and may also inform the optimizations of processing and storage techniques. This study also contributes to our understanding of the relationship between endogenous T concentrations and oil unsaturation, which may improve our knowledge of antioxidative properties of Ts.Consumers are using tree nut oils in food preparations more frequently these days, partially due to the health benefits associated with these specialty oils. Limited research exists in nutritional databases about the lipid constituents – namely the fatty acids, phytosterols, and vitamin E contents – of these oils. This paper reports on the characterization of these constituents in raw and roasted tree nut oils available commercially.