Comparative evaluation of volatile compounds in corn oil during long storage- a preliminary study

A preliminary study for characterizing the volatile compounds of corn oil as related to storage time (0, 1, 16, 18, 20 and 21 months) at room temperature, was carried out. In particular, the chemical markers of negative sensory attributes were monitored in order to highlight flavor changes during storage. For this purpose, headspace-solid-phase microextraction–gas chromatography/mass spectrometry (HS-SPME-GC/MS) analysis was performed. A total of 33 volatile oxidation compounds were identified, which belonged to the following classes; alcohols, aldehydes, ketones, hydrocarbons, carboxylic acids and furanones. Preliminary results evidenced that, after 18 months of storage, 2,2,4,6,6-pentamethylheptane was the predominant hydrocarbon. The oxidative degradation of linoleic acid (the main unsaturated fatty acid present in corn oil) generated many volatile aldehydes. Hexanal (index of oxidative status) was found to be the main aldehyde; however, its content did not change during the shelf-life study, as well as that of pentanal. On the other hand, other aldehydes (such as heptanal, octanal and nonanal), that could have a high impact on corn oil flavor, rose during storage. The carboxylic acids content did not show any variation up to 21 months of storage; in addition, 2-pentylfuran (deriving from oxidation of linoleic acid) was already present after one month of storage, increased until 18 months and degraded thereafter. A comparative study with Flash Chromatography Electronic Nose and Metal Oxides Sensors Electronic Noses for determining the volatile compounds formed as related to storage time at room temperature, was also performed.

A preliminary study for characterizing the volatile compounds of corn oil as related to storage time (0, 1, 16, 18, 20 and 21 months) at room temperature, was carried out. In particular, the chemical markers of negative sensory attributes were monitored in order to highlight flavor changes during storage. For this purpose, headspace-solid-phase microextraction–gas chromatography/mass spectrometry (HS-SPME-GC/MS) analysis was performed. A total of 33 volatile oxidation compounds were identified, which belonged to the following classes; alcohols, aldehydes, ketones, hydrocarbons, carbonic acids and furanones. Preliminary results evidenced that, after 18 months of storage, 2,2,4,6,6-pentamethylheptane was the predominant hydrocarbon. The oxidative degradation of linoleic acid (the main unsaturated fatty acid present in corn oil) generated many volatile aldehydes. Hexanal (index of oxidative status) was found to be the main aldehyde; however, its content did not change during the shelf-life study, as well as that of pentanal. On the other hand, other aldehydes (such as heptanal, octanal and nonanal), that could have a high impact on corn oil flavor, rose during storage. The carbonic acids content did not show any variation up to 21 months of storage; in addition, 2-pentylfuran (deriving from oxidation of linoleic acid) was already present after one month of storage, increased until 18 months and degraded thereafter. A comparative study with Flash Chromatography Electronic Nose and Metal Oxides Sensors Electronic Noses for determining the volatile compounds formed as related to storage time at room temperature, was also performed.