Methodology to Remove Strong Outliers of Non-Climacteric Melon Fruit Aroma at Harvest Obtained by HS-SPME GC-MS Analysis

Abstract

A methodology for making consistent studies of outliers of non-climacteric melon volatile organic compounds at harvest is reported. The juice was squeezed from the fruit of the 'Piel de sapo' cultivar harvested during two consecutive seasons and the aroma volatiles were extracted by headspace solid phase microextraction and measured by gas chromatography coupled to mass-spectrometry. A deconvolution analysis was performed to obtain volatile organic compounds. For multivariate the reliable identification of outliers, compound classes were studied as a percentage of total area counts of the melon compounds identified in the chromatogram by principal component analysis and partial least-squares discriminant analysis, and then verified by correlation analysis, box-whisker plot, and formal tests for univariate outliers. Principal component analysis was the key methodology for selecting outliers in variables that mostly did not follow a normal distribution. The presence of an excess in terms of relative percentage of area and the diversity of minor compounds such as alcohols, terpenes, acids, among others, are usually a sign of anomalous data that can be considered outliers in the aroma of this non-climacteric cultivar. This multivariate approach removed outliers, but kept the variability of aroma among the samples of every cultivar.

Transcriptomic analysis of a near‐isogenic line of melon with high fruit flesh firmness during ripening

“…To analyze VOCs, the juice extracted from melons was filtered through a four‐layer cheesecloth. After 3 min at 23 °C, the mixture containing 28.6% v/v of saturated CaCl 2 solution and the rest of the juice was poured into sterile polypropylene vials, which were stored at −80 °C pending solid‐phase microextraction and analysis by gas chromatography–mass spectrometry (GC/MS) 4,31 …”

“…After 3 min at 23°C, the mixture containing 28.6% v/v of saturated CaCl 2 solution and the rest of the juice was poured into sterile polypropylene vials, which were stored at −80°C pending solid-phase microextraction and analysis by gas chromatography-mass spectrometry (GC/MS). 4,31 RNA extraction RNA extraction was performed using the TRI reagent RNA isolation protocol (1 mL per 20-30 mg lyophilized tissue per extraction) and treated with DNAse.…”

Association among aroma volatiles and other traits in one near-isogenic line with firm flesh texture

“…For volatile organic compounds, juice extracted from melons were filtered through a four-layer cheesecloth. After 3 min at 23 °C, the mixture containing 28.6% v/v of saturated CaCl2 solution) was poured into sterile polypropylene vials, which were stored at −80 °C until analysis (Fernández-Trujillo et al, 2018). VOCs were extracted by solid-phase microextraction.…”

“…The peaks were compared with the experimental spectra of NIST 11 MS library (National Institute of Standards and Technology, Gaithersburg, MD, USA). The methodology of analysis, calculations and identification by deconvolution analysis using AMDIS32 and comparison with linear retention index of compounds reported in literature were previously reported in detail (Fernández-Trujillo et al, 2018). Chemical compounds were verified by a comparison of linear retention indices (LRI) calculated with a homologous series of n-alkanes (C6-C20; Sigma-Aldrich) for the HP-5 MS UI column.…”

“…The integration of the chromatograms, analysis of the individual compounds, separation of aroma groups by chemical compounds, quantification of individual aroma volatile compounds, and removal of strong outliers were performed using the methods described by Fernández-Trujillo et al (2018). The concentrations were quantified from the relation between the areas of the VOCs and the internal standard (1-phenylethanol) using a response factor of 1.…”