Contents



Preface

In recent years, there has been great progress in the understanding of wine chemical and biochemical reactions that occur during winemaking, stabilisation, and wine ageing processes. This book intends to provide to the reader a deep and comprehensive overview of the latest developments in winemaking, stabilisation, and ageing chemistry and biochemistry focused on the most important developments in this critically important oenological area. Thus, the chapters in this book cover different topics of recent advances in the chemical and biochemical knowledge related to

The impact of phenolic compounds and their transformation products in wine sensory properties is currently a hot topic, therefore Chapter 1 presents the most relevant information about the composition, variations, and transformations of phenolic compounds in the winemaking process (alcoholic and malolactic

fermentation) and wine ageing with or without wood contact, that result in complex transformations (copigmentation, cycloaddition, polymerisation, and oxidation) of polyphenols that can influence their sensory properties. Emerging non-thermal technologies open new possibilities in winemaking technology, facilitating the control of indigenous microorganisms and the use of new biotechnologies such as the fermentation with non-*Saccharomyces* yeasts or the use of yeast-bacteria co-inoculations. Chapter 2 reviews the main non-thermal technologies (HHP, UHPH, PEF, eBeam, and US) with application in oenology and their impact in the extraction of phenolic, aroma, and flavour compounds from the grape skins, the elimination of indigenous microorganisms that can result in SO2 reduction during

Nowadays, the quality of wines has improved due to the deep knowledge of the factors involved in wine quality, with many of them related to the grape composition. Despite the advances in our understanding of how the grape berry is developed and which chemical components are important for wine aroma and flavour, there is still much to explore. The study of the compounds responsible for aroma and flavour, as well as their correlation with the wine quality, is ongoing. The advances that are being carried out in different fields such as the determination of aromas and their evolution will allow us to continue expanding this knowledge and these advances are described in Chapter 3. Non-*Saccharomyces* yeasts, considered until recently as undesirable or spoilage yeasts, can improve the chemical composition and aroma profile of the wine. The activity of these yeasts is considered essential for the final wine aroma profile. Given the relevance of its contribution to the quality and typicity of wines, more studies with genetic approaches that explain the metabolic diversity of these yeasts are required. Chapter 4 summarises relevant aspects and pathways involved in the synthesis of aroma compounds by non-*Saccharomyces* yeasts as well as studies at the genetic and transcriptional level associated with their formation. In modern winemaking, oak products alternative to barrels are useful and flexible tools for wineries, enabling them to meet the needs of an increasingly wide and varied market. Although there are observed differences in the wine compositional and sensory properties between wines aged in barrels and those aged

winemaking, stabilisation, and the wine ageing process.

winemaking.
