Suitability of Spanish almond cultivars for the industrial production of almond oil and defatted flour

doi:10.1016/j.scienta.2017.07.051

Scientia Horticulturae

Volume 225, 18 November 2017, Pages 539-546

https://doi.org/10.1016/j.scienta.2017.07.051 Get rights and content

Highlights

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Chemical traits of almond oil and flour are affected by the cultivar.
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In oils differences were found for tri-unsaturated triglycerides OOO and OLL.
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Guara, Ferragnes and Belona are selected as optimal cultivars for oil production.
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Flours show differences in the total mineral content and specific mineral content.

Abstract

The combined evaluation of almond oils and flours obtained by cold pressing provides a comprehensive approach about the nutritional and industrial interest of Spanish almond cultivars for these production purposes. Almonds of ten different cultivars were collected from the same plot to remove the environmental and agricultural management effects on almond chemical traits. Results show that oil yield was similar for all the selected cultivars, however, obtained oils showed significant differences in their fatty acid profile, including essential fatty acids of main nutritional interest. According to the triglyceride profile, significant differences were found for main tri-unsaturated triglycerides (mainly, OOO and OLL) but not for OLO. The concentration of minor components with health promoting properties also was different in the oil obtained from different cultivars. For the selection of the optimal cultivar for oil production, three parameters are proposed as main parameters to consider: iodine value, oxidative stability and oil yield. According to these parameters, the varieties Guara, Ferragnes and Belona would be the most appropriate cultivars for almond oil production. Regarding almond flours obtained, large differences were found in the content of available carbohydrates (276.4–156.1 g/kg) and proteins (581.3–379.4 g/kg) resulting in flours with different potential uses. The total mineral content in flours and the presence of specific minerals (as Fe and Zn) also showed significant differences among cultivars.

Introduction

The almond (Prunus dulcis) is the most important nut in terms of commercial production. Almond tree cultivation is focused mainly in three regions: California, the Mediterranean basin and central Asia – Middle East. Cultivation distribution is limited due to the specific characteristics of hot and dry conditions where the tree produces the highest yields of high quality almonds. Almond production has increased drastically in the last years, from 1,251 billion tons in 2003 to 2,917 billion tons in 2013. The United States and Spain are the larger almond producers, producing, respectively, 43% and 7% of the total almond produced in the last decade (FAO, 2016).

In almond seeds, lipids appear stored in oil droplets (Gallier et al., 2012) and they account from 40 to 67 g/100 g of dry almond weight (Yada et al., 2011). Substantial quantities of triacylglycerol have been reported in almond oil (Martín-Carratalá et al., 1999; Cherif et al., 2004). The proportion of proteins (14–26%) and carbohydrates (2–8%) in the dry almond seed are lower than lipid content, although high variability has been described (Roncero et al., 2016a).

Extensive research has been developed regarding the fatty acid profile of almond oils. Almond oil is mainly composed of mono and di-unsaturated fatty acids (Roncero et al., 2016b). Differences in almond oil fatty acid profile attending to almond origin have been widely described (García-López et al., 1996; Kodad and Socias I Company, 2008; Yada et al., 2011; Maestri et al., 2015). In order of importance, the main fatty acids that appear in almond oil are oleic (50–80%), linoleic (11–37%), palmitic (5–16%) and stearic (1–4%) acids (Askin et al., 2007). Linolenic acid appears in concentrations lower than 0.1% (Maestri et al., 2015) although percentages higher than 11% have been reported in some cultivars (Askin et al., 2007). Almond breeding programs have shown promising results of superior genotypes that could be selected for almond oil production although further work will be needed (Kodad and Socias I Company, 2008, Zhu et al., 2016).

Minor components, as sterols or tocopherols are decisive for almond oil quality (Maestri et al., 2015). Almond oil sterols are almost entirely composed by β-sitosterol (95% of total sterols) and minor concentrations of campesterol and stigmasterol. Previous research found that tocopherol concentration in the Spanish genetic bank varies from 350 to 550 mg/kg oil, with major presence of α-tocopherol (Kodad et al., 2014). Differences in the content of tocopherol homologues in almonds grown in Spain and Morocco were found, but total tocopherol content remained (Kodad et al., 2011). The active role of tocopherols in the oil protection against lipid oxidation makes them an important quality parameter in almond oil.

Beyond cultivar effect, other factors such as soil and climate have proven to have influence on almond oil (García-López et al., 1996, Kodad et al., 2014). The effects of irrigation on almond oil content have also be analyzed, but studies lead to different results, with some finding a significant influence of irrigation supplement on almond oil composition (Schirra and Aggabio, 1989; Sánchez-Bel et al., 2008), while others report opposite results (Egea et al., 2009).

Cultivar selection and the growing region have been reported to have both a significant effect on almond quality and nutritional value (Kodad et al., 2011). Our proposal is the selection of the optimal almond cultivar for production of almond oil and flour considering some of the main cultivars grown in a continental Mediterranean climate in Spain attending to nutritional and industrial production parameters.

Section snippets

Plant material

Almond seeds were collected at an experimental orchard in the Instituto Técnico Agronómico Provincial of Albacete in the southeast Spain in 2015. Ten different cultivars (Antoñeta, Ayles, Belona, Ferraduel, Ferragnes, Guara, Marcona, Penta, Tardona and Vairo) were analysed. One kilogram of almonds were collected from every one of the three trees analyzed within each cultivar. Almonds were picked at the most appropriate harvest date for each cultivar. By considering almond seeds that have all

Oil yield, fatty acid composition and minor components

The differences in the oil content of different almond cultivars do not influence oil yield (Table 1). Extraction yields with the hydraulic press were between 32.2–34.9 g of oil per 100 g of almonds. Although higher extraction yields were obtained in Belona, Marcona and Tardona, significant differences with other cultivars were not found. Press characteristics and established extraction time (20 min) limit a more effective extraction. The slight increase in the moisture content, up to 4%-5%, has

Conclusions

If production of almond oil or almond flour becomes the main destiny of almond production, the selection of the adequate almond cultivar is crucial. Important differences in the oil and flour obtained from almond cultivars grown in a continental Mediterranean climate in Spain have been identified. Significant differences have been obtained in almond oils with regard to the fatty acid profile, oxidative stability, minor components content and the triglyceride composition. Within the main oil

Acknowledgement

This research has been partially supported by a grant from the University of Castilla-La Mancha (Ref. [2015/4062]).

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Research PaperSuitability of Spanish almond cultivars for the industrial production of almond oil and defatted flour

Highlights

Abstract

Introduction

Section snippets

Plant material

Oil yield, fatty acid composition and minor components

Conclusions

Acknowledgement

J. Food Compos. Anal.

Food Chem.

Agric. Water Manage.

Food Chem.

Sci. Hortic.

Food Chem.

Plant Food Hum. Nutr.

LWT-Food Sci. Technol.

LWT-Food Sci. Technol.

Ind. Crop. Prod.

Biochimie

J. Food Compos. Anal.

Food Chem.

ANKOM Technology Method 7, AOCS Approved Procedure Ba6a-05

ANKOM Technology Method 2, AOCS Official Procedure Am 5-04

Kernel fatty acid and triacylglycerol composition for three almond cultivars during maturation

J. Am. Oil Chem. Soc.

Food and Agriculture Organization of the United Nations

The Determination of Nitrogen According to Kjeldahl Using Block Digestion and Steam Distillation

Major fatty acid composition of 19 almond cultivars of different origins. A chemometric approach

J. Agric. Food Chem.

Research Paper
Suitability of Spanish almond cultivars for the industrial production of almond oil and defatted flour