Background and Aims: Two compounds that play an important role in the aroma of Sauvignon Blanc wines are 3-mercaptohexan-1-ol (3MH) and 2-isobutyl-3-methoxypyrazine (IBMP). Little is known about the sensory interaction of these two compounds in Sauvignon Blanc wine and which aroma attributes they elicit at the concentration range normally found in Sauvignon Blanc wines. Methods and Results: 3-Mercaptohexan-1-ol and IBMP were spiked separately or as a mixture to dearomatised Sauvignon Blanc wine at five different concentrations normally occurring in wine, and were assessed by a trained sensory panel. Descriptors were generated by the panel for these compounds when added alone, with overall tropical, guava and passionfruit being generated for 3MH, while overall green, green pepper and grass were used for IBMP. The contribution of these attributes differed, however, depending on the concentration of 3MH and IBMP. Conclusions: There is sensory interaction between 3MH and IBMP. The sensory attributes linked to each compound can depend on the concentration of both compounds present in wine. It is possible that wine producers may use this phenomenon to achieve a specific style of Sauvignon Blanc wine. Significance of the Study: This study might allow wine producers to predict which aroma profile to expect when 3MH and IBMP occur at a certain concentration in Sauvignon Blanc wine.

The effect of repetitive controlled oxidation on the chemical and sensory composition of a fresh and fruity style Sauvignon blanc wine was investigated. Chemical analyses were conducted together with extensive sensory profiling. A decrease in volatile thiols responsible for the fruity nuances and an increase in oxidation-related compounds, such as acetaldehyde, during the course of the oxidation was observed. The wine evolved from a fresh and fruity one to one with slight oxidation and then developed extreme oxidative characteristics. The control samples (no oxygen added) developed a "cooked" character that could indicate the formation of "reductive" compounds in these wines. Conversely, the wines that received a single dose of oxygen did not develop this flavor and were perceived to be fresher and fruitier than the control samples. The color of the wine evolved before the disappearance of the pleasant aroma.

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The fourth agricultural revolution is leading us into a time of using data science as a tool to implement precision viticulture. Infrared spectroscopy provides the means for rapid and large-scale data collection to achieve this goal. The non-invasive applications of infrared spectroscopy in grapevines are still in its infancy, but recent studies have reported its feasibility. This review examines near infrared and mid infrared spectroscopy for the qualitative and quantitative investigation of intact grapevine organs. Qualitative applications, with the focus on using spectral data for categorization purposes, is discussed. The quantitative applications discussed in this review focuses on the methods associated with carbohydrates, nitrogen, and amino acids, using both invasive and non-invasive means of sample measurement. Few studies have investigated the use of infrared spectroscopy for the direct measurement of intact, fresh, and unfrozen grapevine organs such as berries or leaves, and these studies are examined in depth. The chemometric procedures associated with qualitative and quantitative infrared techniques are discussed, followed by the critical evaluation of the future prospects that could be expected in the field.

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