Agronomijas v stis - Latvijas Lauksaimniecības universitāte

KopsavilkumsEiropas melleĦu (Vaccinium myrtillus) ogas no dienvidu, vidus un ziemeĜu Norvēăijas savvaĜasaudzēm tika pētītas kā daĜa no 2008. gadā uzsāktā projekta par šo ogu kultivēšanu unekspluatēšanu. DaĜa no augĜu kvalitātes analīžu uzdevumiem bija identificēt un aprakstīt melleĦuaromātu. Gaistošās vielas tika izdalītas ar HS-SPME metodi un analizētas ar gāzu hromatogrāfijas– masu spektrometrijas (GC/MS) metodi. Kopumā tika noteiktas 132 aromātu veidojošas gaistošāsvielas, no kurām 99 sastāvdaĜu struktūras tika identificētas, balstoties uz spektra datubāzesmeklējumiem un izdalīšanās laiku, tai skaitā atrastas sastāvdaĜas, kas iepriekš mellenēs navaprakstītas. Noteiktās alifātiskās un aromātiskās struktūras vielas piederēja dažādām ėīmiskajāmgrupām ,tādām kā alkāni, skābes, spirti, aldehīdi, ēteri, ketoni, terpēni. Desmit galvenās sastāvdaĜas(galvenokārt C 4 -, C 6 - un C 9 - struktūras) sastādīja, vidēji 65 – 75 % no relatīvā visu noteiktosastāvdaĜu daudzuma. Tomēr HS-SPME analīze uzrādīja Ĝoti daudzveidīgu gaistošo vielu sastāvu,ieskaitot terpēnus (23 sastāvdaĜas, piemēram, p-cimēns, 1,8-cineols, linalols) un aromātiskasstruktūras (10 sastāvdaĜas, piemēram, benzaldehīds, etilbenzoāts, 2-feniletilacetāts,benzilbenzoāts), kas nosaka raksturīgo un bagātīgo melleĦu aromātu.Key words: Vaccinium myrtillus L., headspace (HS), solid-phase microextraction (SPME), gaschromatography/mass spectrometry (GC/MS), aroma, quality.IntroductionEuropean blueberry (Vaccinium myrtillus L.), also called bilberry, is a perennial dwarf shrub in theEricaceae family, being native to northern and eastern parts of Europe and Asia. Compared to otherspecies in the same genus e.g. highbush blueberry (V. corymbosum L.), the wild blueberriesproduce fruits with a higher content of desirable polyphenols and other health-beneficialcompounds (Giovanelli and Buratti, 2009). Furthermore, the characteristic and pleasant flavour ofberries from wild-growing plants is very complex compared to cultivated highbush blueberries(Parliment and Kolor, 1975; Hirvi and Honkanen, 1983a) and rabbiteye blueberries (Horvat et al.,1996). Already in 1969, Von Sydow and Anjou published results about the vast variety of 109aroma volatiles found in V. myrtillus, and described 19 aliphatic alcohols, 24 aliphatic aldehydesand ketones, 26 terpene derivatives, 24 aromatic compounds, and 16 other chemical structures.Berry samples from putative progenitor species of cultivated highbush, rabbiteye and lowbushblueberries have been shown to contain many of the same aroma volatiles (Baloga et al., 1995),and later reports underscored the complexity of aroma patterns also of cultivated Vaccinium speciesthrough the identification of new potential key aroma volatiles such as sulphur-compounds(Hanoglu and Pucarelli, 2007) and other chemical structures (Di Cesare et al., 1999). Major goalsof our preliminary study on aroma volatile composition of berrries from wildgrowing V. myrtillusplants in Norway were the (1) Identification of aroma-impact compounds, (2) Influence ofmaturation stage on aroma patterns, and (3) Potential effect of location on berry aroma , in order tocharacterize the significance of different factors affecting the flavour properties of blueberries.Materials and MethodsPlant Material. Blueberry samples from different wild populations from South, Mid and NorthNorway where harvested at maturation stage in August-September 2008 and stored at -20°C priorto extraction and analysis.Aroma Volatile Analysis. Frozen berries were cut into halves and a total of 3 g from single halvesof 10 – 15 fruits were placed in a 15 ml headspace vial (Supelco Inc.). After adding 5 ml H 2 O and 1g NaCl, the vial was closed with a screw cap with Teflon-coated septum, and the sample wasconstantly agitated on a magnetic stirrer during extraction (45 min). Headspace solid-phasemicroextraction (HS-SPME) was applied for isolation and concentration of volatile aromacompounds by using a manual SPME holder (Supelco Inc.) with a PDMS/DVB-coated 65 µm fibreexposed to the atmosphere in the sample vial (Rohloff, 2004). HS-SPME sampled volatiles weredesorbed in the the injection port of a gas chromatograph (GC) for 3 min. Aroma volatiles wereanalysed using a VARIAN Star 3400 CX GC coupled with a Saturn 3 mass spectrometer (GC/MS).GC separations were carried out on a HP-5MS capillary column (30 m × 0.25 mm i.d., filmthickness 0.25 µm). Injection temperature was 220 °C, and the interface was set to 220 °C. The99