Effect of grape heterogeneity on wine chemical composition and sensory attributes forVitis viniferacv. Cabernet Sauvignon

Abstract

Background and Aims: The wine industry widely acknowledges that grape heterogeneity exists throughout any given vineyard at the time of harvest. There is a lack of understanding, however, of the effects that heterogeneity has on wine composition and sensory qualities. This study compared the chemical composition and sensory attributes of wines produced using parcels of grapes with known heterogeneity. Methods and Results: Cabernet Sauvignon berries were sorted into maturity classes using five density baths. Winemaking was undertaken with a varying proportion of sorted berries to obtain wines arising from low, moderate and high grape heterogeneity musts, containing the same level of TSS for comparison to a Control wine that represented the inherent heterogeneity of the harvested vines. Wines were distinguished by the concentration of 3-isobutyl-2-methoxypyrazine, total anthocyanins and total phenolics, with the low heterogeneity wine having the highest values of each measurement. The high heterogeneity wine was characterised by a higher concentration of acetic acid. Principal component analysis of rate-allthat-apply sensory attribute scores revealed that low and moderate heterogeneity wines were characterised by floral and pepper aroma attributes, and the high heterogeneity wine by sour taste. Conclusions: The differing levels of grape heterogeneity had a subtle effect on Cabernet Sauvignon wine colour, aroma and taste attributes, but it was demonstrated that the level of grape heterogeneity could be of relevance if it translated into differences in wine quality and style. Significance of the Study: The potential impact of grape heterogeneity on the chemical composition and sensory profile of Cabernet Sauvignon wine was highlighted.

Rootstock, Vine Vigor, and Light Mediate Methoxypyrazine Concentrations in the Grape Bunch Rachis ofVitis viniferaL. cv. Cabernet Sauvignon

“…SPME–GC–MS was performed with an Agilent 7890B gas chromatograph (Santa Clara, CA) fitted with an Agilent GC Injector 80 and coupled to an Agilent 7000C triple-quadrupole mass spectrometer. SPME and chromatographic conditions were reported in Armstrong et al with a slight modification to the injector temperature (set to 250 °C). For multiple-reaction monitoring, transitions were as reported by Armstrong et al with the addition of m / z 151.0 → 123.0, 151.0 → 119, and 124.0 → 94.0 for SBMP; 154.0 → 126.0 and 127.0 → 95.0 for d 3 -SBMP (internal standard); and 155.0 → 127.0, 140.0 → 105.0, 127.0 → 95.0, and 155.0 → 140.0 for d 3 -IPMP (internal standard).…”

“…SPME and chromatographic conditions were reported in Armstrong et al with a slight modification to the injector temperature (set to 250 °C). For multiple-reaction monitoring, transitions were as reported by Armstrong et al with the addition of m / z 151.0 → 123.0, 151.0 → 119, and 124.0 → 94.0 for SBMP; 154.0 → 126.0 and 127.0 → 95.0 for d 3 -SBMP (internal standard); and 155.0 → 127.0, 140.0 → 105.0, 127.0 → 95.0, and 155.0 → 140.0 for d 3 -IPMP (internal standard). Underlined transitions were used for quantification and all transitions were monitored with a 50 ms dwell time.…”

Use of auxin to delay ripening: sensory and biochemical evaluation of Cabernet Sauvignon and Shiraz

“…The predominant grape methoxypyrazine, 3-isobutyl-2-methoxypyrazine (IBMP), was quantified in frozen, powdered Cabernet Sauvignon grape berry tissue, as described by Armstrong et al (2021); rotundone was quantified in the equivalent Shiraz samples following the method of Davies et al (2015).…”

Timing of auxin treatment affects grape berry growth, ripening timing and the synchronicity of sugar accumulation

“…The phenomenon of NAA treatment altering the synchronicity of the ripening of the grape berry population, observed previously (Böttcher et al 2011b(Böttcher et al , 2012, may mean that the metabolism of these berries is better synchronised in these populations. Armstrong et al (2021) sorted a berry population into different classes on the basis of density and showed that the level of heterogeneity had demonstrable effects on wine composition and sensory characteristics. While some variation in berry developmental stage might be useful in providing complexity to wine, too much heterogeneity may reduce consumer acceptance.…”