Bunch microclimate influence amino acids and phenolic profiles of Pinot noir grape berries

Abstract

IntroductionThe increase of temperature due to climate change at different phenological stages of grapevine has already been demonstrated to affect accumulation of primary and secondary metabolites in grape berries. This has a significant implication for Pinot noir especially in New Zealand context as these compounds can have direct and indirect effects on wine quality. MethodsThis study investigates how varying bunch microclimate through changes in temperature applied at veraison stage can affect: fresh weight, total soluble solids, the accumulation of anthocyanins, total phenolics and amino acids of the grape berries. This was studied over two growing seasons (2018/19 and 2019/20) with Pinot noir vines being grown at two different temperatures in controlled environment (CE) chambers. The vines were exposed to 800 µmol/m2/s irradiance with diurnal changes in day (22°C or 30°C) and night (15°C) temperatures. This experimental set up enabled us to determine the accumulation of these metabolite at harvest (both seasons) and throughout berry development (second season). Results and discussionThe results showed that berry weight was not influenced by temperature increase. The total soluble solids (TSS) were significantly increased at 30°C, however, this was not at the expense of berry weight (i.e., water loss). Anthocyanin content was reduced at higher temperature in the first season but there was no change in phenolic content in response to temperature treatments in either season. The concentrations of total amino acids at harvest increased in response to the higher temperature in the second season only. In addition, in the time course analysis of the second season, the accumulation of amino acids was increased at mid-ripening and ripening stage with the increased temperature. Significant qualitative changes in amino acid composition specifically the α-ketoglutarate family (i.e., glutamine, arginine, and proline) were found between the two temperatures. SignificanceThis study is the first to provide detailed analysis and quantification of individual amino acids and phenolics in Pinot noir in response to changes in temperature applied at veraison which could aid to develop adaptation strategies for viticulture in the future.

Phenolic, Amino Acid, Mineral, and Vitamin Contents during Berry Development in ‘Italia’ and ‘Bronx Seedless’ Grape Cultivars

“…The higher concentrations of amino acids in Bronx Seedless, including aspartate, glutamate, and valine, suggest its potential for producing wines with distinctive sensory attributes. This is in line with prior studies highlighting the influence of grape variety on amino acid composition and its implications for wine flavor, as noted by Murillo-Peña et al [23] and Moukarzel et al [24]. Moreover, the observed changes in amino acid content emphasize the necessity of precise harvesting decisions to ensure the desired flavor profiles in wines, as discussed in previous research by Ma et al [25].…”

From acidity to sweetness: a comprehensive review of carbon accumulation in grape berries

“…This exposure also increases levels of hydroxybenzoic acid, gallic acid, ellagic acid, and anthocyanins, while decreasing flavan-3-ols and amino acids compared to shaded berries (Downey et al 2004 ; Somkuwar et al 2023 ). In contrast, shaded bunches show higher proline concentrations, underlining the profound impact of sunlight on the biochemical composition and quality of grape berries (Moukarzel et al 2023 ). Additionally, the temperature of berry skins, elevated by direct sunlight, affects enzymatic activities crucial for sugar metabolism.…”

“…Additionally, the temperature of berry skins, elevated by direct sunlight, affects enzymatic activities crucial for sugar metabolism. Sunlight also influences the expression of genes involved in sugar transport and metabolism, further impacting sugar accumulation (Moukarzel et al 2023 ). However, excessive sunlight or heat can cause detrimental effects like berry sunburn and reduced photosynthetic efficiency, potentially diminishing sugar content of berries (Gambetta et al 2021 ).…”