Changes in the Chemical Composition of Plum Distillate During Maturation with Oak Chips under Different Conditions

U radu je ispitan utjecaj dozrijevanja u kontaktu s hrastovim trijeskama na sastav i koncentraciju destilata šljive. Destilatu šljive su tijekom starenja dodane lagano pržene trijeske francuskog hrasta (Quercus sessiflora i Quercus robur) ili trijeske dobivene od starih bačava u kojima je odležao konjak. Ispitan je utjecaj količine dodanih trijeski, temperature, načina dozrijevanja (statičnog ili uz cirkulaciju) te primjene ultrazvuka. Dozrijevanjem destilata šljive u prisutnosti hrastovih trijeski povećala se količina ekstraktibilnih organskih spojeva (uključujući tanine) i promijenila boja destilata, u ovisnosti o vrsti i količini dodanih trijeski te uvjetima dozrijevanja. Koncentracija se šećera, kao što su glukoza, ksiloza i arabinoza, povećala ovisno o uvjetima dozrijevanja i vrsti trijeski. Razgradnjom lignina oslobođene su određene količine sinapaldehida, siringaldehida, coniferaldehida i vanilina, u ovisnosti o uvjetima pokusa. Od hlapljivih spojeva, koncentracija se viših alkohola i alifatskih (acikiličkih) aldehida u većem broju varijanti pokusa smanjila, dok se koncentracija furanskih aldehida, ovisno o vrsti i količini trijeski te uvjetima dozrijevanja, povećala. Koncentracija se estera, poput etilacetata u većem broju varijanti pokusa smanjila, a etil-kaproata, etil-kaprilata i etil- -kaprata postupno povećala. Neki su fenoli i laktoni pronađeni u uzorcima destilata nakon dozrijevanja, a najmanje su koncentracije tih spojeva pronađene u uzorcima destilata dozrelog u kontaktu s hrastovim trijeskama dobivenim od bačava u kojima je odležao konjak.
This study investigates the effect of ageing on the qualitative and quantitative composition of plum distillate in contact with oak wood chips. Maturation was performed with lightly toasted French oak (Quercus sessiflora and Quercus robur) chips or oak chips made from fragments of empty barrels that had been used for ageing cognac. The effects of oak chip dose, process temperature, ageing system (static or circulatory) and ultrasound treatment were assessed. Maturation of plum distillate samples with oak chips resulted in higher levels of extractable organics (including tannins) and colour changes, which were correlated with the type and dose of oak chips, and the conditions of maturation. The content of sugars such as glucose, xylose and arabinose also increased, depending on the conditions and type of oak chips. Degradation of lignin resulted in liberation of sinapaldehyde, syringaldehyde, coniferaldehyde and vanillin, with intensities depending on the applied parameters. In terms of volatiles, decreases in the concentration of higher alcohols and aliphatic aldehydes were observed in the majority of maturation experiments, while concentrations of furanic aldehydes increased depending on the type and dose of oak chips, as well as on the conditions of maturation. The quantities of esters such as ethyl acetate decreased in the majority of experimental variants, whereas concentrations of ethyl caproate, ethyl caprylate and ethyl caprate increased gradually. Some phenols and lactones were detected in all matured samples, with the lowest levels found in the samples aged with oak chips made from cognac barrels.