Chemical Characterization of Virgin Almond and Hazelnut Oils and Their By‐Products

Abstract

Various cultivars of almonds (“Ferragnes,” “Guara,” “Largueta,” and “Marcona”) and hazelnuts (“Negret,” “Pauetet,” and “Tonda”), particularly their virgin oils and by‐products, are evaluated in this study. The almond and hazelnut virgin oils present high contents of oleic acid (59–73% and 76–80%, respectively) and α‐tocopherol (420–542 and 310–378 mg kg–1, respectively), as compared with other virgin vegetable oils. Aldehydes are the major contributors to their aromatic profile (54–74% almond oil and 30–40% hazelnut oil of total content), especially, benzaldehyde in almond oils (1.35–7.52 mg kg–1), and hexanal in hazelnut oils (0.99–1.27 mg kg–1). Statistical differences exist between the virgin almond and hazelnut oils and their varieties, for most of the chemical compounds studied. While all the nut varieties are high in polar phenolic compounds, “Ferragnes” almonds (1262 mg kg–1) and “Negret” hazelnuts (1720 mg kg–1) stand out. Accordingly, high antioxidant activity is also observed. Finally, the residual cakes may be considered a good source of polar phenolic compounds (823–2064 mg kg–1 almond cakes, 2261–4179 mg kg–1 hazelnut cakes), possessing high antioxidant capacity with potential applications of these by‐products as functional ingredients in food and non‐food formulations. Practical Applications: Virgin nut oils are gaining consumers’ preference due to their unique organoleptic attributes and potential health effects. It is therefore very relevant to establish their specific chemical composition, directly related to their properties, and that are greatly affected by the cultivar.

Promotion of almond oil from the Ferragnes variety, a predominant cultivar in young almond plantations in eastern Morocco

“…The richness of tocopherols in almond oil contributes to the antioxidant properties of oils; they also have protective roles in biological systems as well as other neuroprotective properties [19]. Our results are similar to those recorded in Spain 475 mg/kg [20] and higher compared to the ones obtained in Turkey (186.6 mg/kg) [21]…”

Review about Non-Lipid Components and Minor Fat-Soluble Bioactive Compounds of Almond Kernel

“…The interest aroused by these substances has boosted the development of new methods for their determination, increasing exponentially the published articles about them. Another important source of data is due to the recent interest in almond oil extraction as virgin edible oil [ 11 , 12 , 13 , 30 , 31 , 32 , 33 , 34 , 35 ]. In this sense, almond oil has been widely characterized, but oil extraction industries generate a by-product derived from the grinding of the pressing cake, which originates a partially defatted flour where the non-lipidic fraction takes on a special relevance.…”

“…Tree nuts contain very low amounts of carotenoids [ 27 ]. Marginal pigments content has been found in wild almond kernels [ 92 ], and the only study that indicates the chlorophyll and carotenoid content for cultivated almond kernels is due to Ojeda-Amador et al [ 35 ], who found 8.5–18 mg/kg of chlorophyll and 5.3–8.8 mg/kg of carotenoids in almond oils. Carotenoids concentration in almond kernels is low; consequently, it does not constitute an important dietary source of these substances [ 97 ].…”

“…The skin represents approximately 4% of the total almond weight and contains 70–100% of total phenols present in the nut [ 109 ]. The residual cakes could be expected to possess an added value for applications in food formulations since they are a good source of phenolic compounds that concentrate in the by-product due to their polar properties [ 35 ].…”

“…Ojeda-Amador et al [ 35 ] analyzed volatile compounds which are related to sensory notes, such as fruit/banana (hexanol), oily/green–sweet (hexanal), fruity (pentanol) and bitter almonds (benzaldehyde). The most important family found in all the varieties studied was that of aldehydes (1.35–7.52 mg/kg).…”