Volatile composition and aroma activity of guava puree before and after thermal and dense phase carbon dioxide treatments

Abstract

Volatiles from initially frozen, dense phase carbon dioxide (DPCD)- and thermally treated guava purees were isolated by solid phase microextraction (SPME), chromatographically separated and identified using a combination of gas chromatography-mass spectrometry (GC-MS), GC-olfactometry (GC-O), and GC-pulsed flame photometric detector (GC-PFPD, sulfur mode). Fifty-eight volatiles were identified using GC-MS consisting of: 6 aldehydes, 2 acids, 15 alcohols, 6 ketones, 21 esters, and 8 terpenes. Eleven volatiles were newly identified in guava puree. Hexanal was the most abundant volatile in all 3 types of guava puree. Ten sulfur compounds were identified using GC-PFPD of which 3 possessed aroma activity and 3 were not previously reported in guava puree. Both treatments profoundly reduced total sulfur peak areas and produced different peak patterns compared to control. Thermal treatment reduced total sulfur peak area 47.9% compared to a loss of 34.7% with DPCD treatment. Twenty-six volatiles possessed aroma activity. (Z)-3-Hexenyl hexanoate was the major contributor to the aroma of the freshly thawed and DPCD-treated guava puree. DPCD treatment reduced total MS ion chromatogram (MS TIC) peak area 35% but produced a GC-O aroma profile very similar to control. Whereas thermal treatment reduced total TIC peak area only 8.7% compared to control but produced a 35% loss in total GC-O peak intensities.

Keywords: aroma active volatiles; sulfur volatiles; thermal processing.