Identification and quantification of volatiles appearing during frozen storage of hake and mackarel

Cilj ovog istraživanja bio je kvalitativno i kvantitativno odrediti hlapljive spojeve koji nastaju oksidacijom masnih kiselina tijekom 10-omjesečnog skladištenja ribe u zamrznutom stanju pri -18 °C. Istraživanje je provedeno na uzorcima oslića (Merlucius merlucius) i skuše (Scomber scombrus). Hlapljivi sastojci arome izolirani su primjenom tehnike mikroekstrakcije na čvrstoj fazi (HS-SPME), a zatim su analizirani uz pomoć plinsko kromatografsko – maseno spektrometrijske instrumentalne metode (GC–MS). Promatrane su promjene u koncentracijama 14 odabranih spojeva koji su prethodno prepoznati u literaturi kao indikatori promjena tijekom skladištenja, a provedena je i detaljna analiza koja je obuhvatila sve spojeve koji su se pojavili tijekom 10 mjeseci skladištenja, s posebnim naglaskom na one koji se pojavljuju 1. i 10. mjeseca skladištenja. U obje je vrste ribe došlo do blage oksidacije masnih kiselina tijekom skladištenja. Za praćenje oksidacije masnih kiselina u skuši kao pogodni spojevi pokazali su se 2-butanon, heksanal, heptanal i benzaldehid. The aim of this study was to qualitatively and quantitatively define volatile compounds that occur as a result of the fatty acids oxidation during the 10 – months – long frozen storage of fish at the temperature of -18 °C. The research was conducted on hake (Merlucius merlucius) and mackerel (Scomber scombrus) samples. Volatile aroma compounds were isolated by the usage of solid phase microextraction technique (HS-SPME), and subsequently analyzed using gas chromatography – mass spectrometric instrumental method (GC-MS). Changes in 14 chosen compounds which are previously known from the literature and considered to be indicators of storage occurring changes are observed. Furthermore, a detailed analysis was conducted taking into account all the compounds occurring during the 10 – month storage, with the stress on those occurring in both the 1st and 10th month. In both types of fish a mild oxidation of fatty acids was observed. 2-butanone, hexanal, heptanal and benzaldehyde proved to be suitable compounds for monitoring the oxidation of fatty acids in mackerel.