Classification of Almond Cultivars Using Oil Volatile Compound Determination by HS‐SPME–GC–MS

Abstract

Protected designations of origin ''Alicante'' and ''Jijona'' nougats are manufactured products produced using raw materials from Eastern Spain. In order to avoid adulteration practices, determination of volatile compounds from three different almond cultivars (Spanish Guara and Marcona and, from the USA, Butte) was performed to obtain a set of parameters for discrimination between Spanish and American cultivars. Factorial experimental design was applied for the development of a headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) analytical method for isolation and determination of the volatile compounds in almond oils. Main HS-SPME variables optimized were extraction temperature, extraction time, and stirring speed. Several volatile compounds including aldehydes, alkanes, alcohols and aromatic hydrocarbons were identified. Multivariate techniques were applied for classification and discrimination of the different almond cultivars studied. Specifically, cluster and stepwise linear discriminant analysis (LDA) were used, with LDA showing the best performance. The results obtained demonstrated that the proposed method combined with multivariate statistical analysis can be successfully applied for discrimination among different almond cultivars.

Characterization of Almond Cultivars by the Use of Thermal Analysis Techniques. Application to Cultivar Authenticity

“…In this way, the Butte cultivar shows low concentrations of oleic and stearic acids and high linoleic acid content, while the Guara cultivar shows high stearic acid and low palmitoleic acid contents [2]. Some differences have been also reported in terms of volatile compounds, since octanal and nonanal are oleic acid derivatives and consequently their contents are expected to be lower in samples from the Butte cultivar compared with the Spanish almond cultivars [6].…”

“…Fatty acid profiles [2], triglycerides and tocopherol composition [3] as well as the volatile compounds profile [6] have been proposed as discriminant parameters to differentiate almond cultivars. However, these methods are quite tedious, raising the need for fast and reliable methods.…”

Comparison of the Profile and Composition of Volatiles in Coniferous Needles According to Extraction Methods

“…In addition, it is important to eliminate any interfering matrix to improve the detection limits for the specific compounds [25]. This has prompted the development of several extraction methods for sample preparation [16,20]. The volatiles extracted by the three extraction methods differed significantly not only with respect to their profiles, but also in their contents (Table 1, Table 2 and Table 3).…”

“… 1 Retention indices (RI) were determined using n -paraffins C 7 -C 22 as external standards on Cyclodex-B column; 2 All volatile compounds, positively identified by matching mass spectrum and retention index with those of an authentic standard, are listed by the order of their RI in a chemical class; 3 Volatile compounds were calculated with the relative peak ratio of their peak areas to that of internal standard ( n = 3) ± standard deviation; 4 Identification of volatiles was performed requiring the s following criteria: A, mass spectrum and retention index were consistent with those of an authentic standard (positive identification); B, mass spectrum and retention index were consistent with those of literatures [6,20,25]; C , mass spectrum was consistent with that of Wiley 7n spectral database (Agilent Technologies) or by manual interpretation (tentative identification); 5 Difference letters mean significant differences ( p < 0.05) between three different needle samples according to three different cultivar species or extraction methods by Duncan’s multiple range test; 6 nd = not detected; 7 CAS Registry number.…”

“…Solid-phase microextraction (SPME) and solvent extraction (SE) are the predominant methods used in many studies to extract the volatile compounds [16,17,18,19]. SPME is particularly efficient for extracting highly volatile aroma compounds and can easily be used for sample preparation without requiring a solvent [20]. On the other hand, SE is dependent upon the solubility of the solvent and cannot avoid extracting non-volatile compounds such as fat, wax, and pigments, in addition to volatile compounds [21].…”