Cohen Seth D, Tarara Julie M, Kennedy James A
Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, USA.
Anal Chim Acta. 2008 Jul 21;621(1):57-67. doi: 10.1016/j.aca.2007.11.029. Epub 2007 Nov 23.
This study assessed the impact of fruit temperature on the phenolic metabolism of grape berries (Vitis vinifera L. cv. Merlot) grown under field conditions with controlled exposure to sunlight. Individual cluster temperatures were manipulated in situ. Diurnal temperature fluctuation was damped by daytime cooling and nighttime heating of clusters. Daytime-only and nighttime-only temperature controls were applied for comparison. Berry temperatures were recorded continuously to compare the chemical data. Samples collected at véraison indicated that damping the diurnal temperature fluctuation advanced the onset of ripening. Those berries were larger (double-damped: 0.753+/-0.015gberry(-1) vs control: 0.512+/-0.034gberry(-1)) and more colored than all others. Development of phenolic metabolites was followed by two reversed-phase high performance liquid chromatography methods and gel permeation chromatography. These methods provided information on anthocyanins, proanthocyanidins, flavonols, flavan-3-ol monomers, and polymeric material. Damping the diurnal temperature fluctuation reduced proanthocyanidin mean degree of polymerization (double-damped: 21.8+/-1.0 vs control: 28.0+/-1.7). Proanthocyanidin accumulation at véraison was linearly related to heat summation over the developmental period with nighttime heating yielding the highest concentration and daytime cooling yielding the lowest (night-heat: 1.46+/-0.13mgberry(-1) vs day-cool: 0.97+/-0.09mgberry(-1)). Damping the diurnal temperature fluctuation had a marked effect on the rate of fruit development whereas total heat summation had more of an effect on phenolic metabolism alone. The results provide insight on the direct effect of temperature on phenolic metabolism.
本研究评估了果实温度对在田间条件下生长、光照可控的葡萄浆果（葡萄品种美乐）酚类代谢的影响。在原位对单个果穗温度进行调控。通过白天对果穗降温、夜间对果穗加热来抑制昼夜温度波动。设置仅白天温度控制和仅夜间温度控制作为对照。持续记录浆果温度以比较化学数据。在转色期采集的样本表明，抑制昼夜温度波动可使成熟提前开始。这些浆果比其他所有浆果更大（双抑制：0.753±0.015克/浆果 vs 对照：0.512±0.034克/浆果）且颜色更深。采用两种反相高效液相色谱法和凝胶渗透色谱法跟踪酚类代谢产物的变化。这些方法提供了有关花青素、原花青素、黄酮醇、黄烷 - 3 - 醇单体和聚合物质的信息。抑制昼夜温度波动降低了原花青素的平均聚合度（双抑制：21.8±1.0 vs 对照：28.0±1.7）。转色期原花青素的积累与整个发育时期的热量总和呈线性相关，夜间加热导致浓度最高，白天降温导致浓度最低（夜间加热：1.46±0.13毫克/浆果 vs 白天降温：0.97±0.09毫克/浆果）。抑制昼夜温度波动对果实发育速率有显著影响，而总热量总和对酚类代谢的影响更为显著。这些结果为温度对酚类代谢的直接影响提供了见解。
