Abstract
Understanding the aroma profile of wines made from cold climate grapes is needed to help winemakers produce quality aromatic wines. The current study aimed to add to the very limited knowledge of aroma-imparting compounds in wines made from the lesser-known Frontenac and Marquette cultivars. Headspace solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) with simultaneous olfactometry was used to identify and quantify selected, aroma-imparting volatile organic compounds (VOC) in wines made from grapes harvested at two sugar levels (22° Brix and 24° Brix). Aroma-imparting compounds were determined by aroma dilution analysis (ADA). Odor activity values (OAV) were also used to aid the selection of aroma-imparting compounds. Principal component analysis and hierarchical clustering analysis indicated that VOCs in wines produced from both sugar levels of Marquette grapes are similar to each other, and more similar to wines produced from Frontenac grapes harvested at 24° Brix. Selected key aroma compounds in Frontenac and Marquette wines were ethyl hexanoate, ethyl isobutyrate, ethyl octanoate, and ethyl butyrate. OAVs >1000 were reported for three aroma compounds that impart fruity aromas to the wines. This study provides evidence that aroma profiles in Frontenac wines can be influenced by timing of harvesting the berries at different Brix. Future research should focus on whether this is because of berry development or accumulation of aroma precursors and sugar due to late summer dehydration. Simultaneous chemical and sensory analyses can be useful for the understanding development of aroma profile perceptions for wines produced from cold-climate grapes.
Highlights
The grape berry undergoes significant changes during ripening, including acid catabolism and the accumulation of sugar, anthocyanins, flavor and aroma compounds [1]
Ethanol was present in all samples, including the matrix blank
Since ethanol is present in all samples, it is not included in the further discussion
Summary
The grape berry undergoes significant changes during ripening, including acid catabolism and the accumulation of sugar, anthocyanins, flavor and aroma compounds [1]. Examples include 2-methoxy-3-isobutyl pyrazine (a green bell pepper aroma) reported in Sauvignon blanc [11] or 4-vinylguaiacol (spicy, clove aromas) found in Gewurztraminer [12] Some varieties such as Chardonnay or Seyval do not have characteristic aromas originating from one or two specific compounds [13,14]. VOC partitioning into headspace is suppressed with increasing concentration of ethanol in wine samples; ethanol influenced matrix-VOC partitioning more than glucose levels [19], possibly affecting SPME extraction efficiency of flavor and aroma compounds. Evaluating the total aroma compounds present in headspace of Frontenac and Marquette wines is important to identify potential varietal aroma character. This information can be used to compare the aroma of Frontenac and Marquette wines to the more recognizable vinifera wines (Figure 1).
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