Development of a quantitative method for headspace analysis of methylsulfanyl-volatiles from kiwifruit tissue

Minor fruit volatiles are likely to be missed using sampling techniques optimized for the extraction of major compounds. This can be a disadvantage if these minor compounds contribute to characteristic fruit flavors. In this comparative study, headspace solid-phase microextraction (HS-SPME) and dynamic headspace sampling (DHS) parameters were systematically optimized to ensure highest extraction yields of methylsulfanyl-volatiles from kiwifruit tissue samples. A significant “salting-out” effect from the fruit matrix was observed using both sampling techniques after (NH4)2SO4 saturation. HS-SPME at optimized conditions (polydimethylsiloxane-divinylbenzene-coated fiber, (NH4)2SO4 saturation, 5 min equilibration and 20 min sampling at 40 °C) was faster and more convenient to use than DHS for qualitative purposes. Despite this, the qualitative and quantitative methylsulfanyl-volatile profile was improved using optimized DHS ((NH4)2SO4 saturation; sampling time 20 h; flow rate 30 mL min− 1) compared with HS-SPME, making this the more sensitive and preferred method for quantitative studies. The optimization strategies for increasing headspace extraction yields of trace compounds presented in this study can easily be applied to tissue samples from other fruit.