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 winemaking, stabilisation, and the wine ageing process.

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 winemaking.

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

**II**

**Chapter 8 173**

**Chapter 9 205** Pathogenesis-Related Proteins in Wine and White Wine Protein Stabilization

**Chapter 10 223**

Wine Stabilisation: An Overview of Defects and Treatments *by Fernanda Cosme, Luís Filipe-Ribeiro and Fernando M. Nunes*

Cork and Cork Stoppers: Quality and Performance

*by Bin Tian and Roland Harrison*

*by Vanda Oliveira and Helena Pereira*

with alternative products, Chapter 5 deals with the main oenological uses of oak wood chips, the chemical transformations that underlie this practice, and the effect of their utilization on wine quality.

Port wine is a traditional and worldwide renowned fortified wine produced in the Douro Demarcated Region (DDR) Northeast of Portugal. The quality and uniqueness of the different Port wine styles are highly dependent on the ageing process, namely time, temperature, and oxygen levels. The chemical changes occurring during the Port wine ageing process result in significant changes in colour and aroma according to the different ageing conditions employed for the different Port wine styles. In Chapter 6, a broad and generic overview of the known and potential chemical changes occurring during ageing of Port wine is described, as well as the known chromatic and aroma characteristics of the different Port wine styles and the specific ageing processes, reductive or oxidative way. However, more studies are still needed to deepen our knowledge in order to understand and control the reactions involved in the Port wine ageing process that contribute to its uniqueness.

Astringency is a tactile sensation evoked in the mouth by polyphenols, mainly tannins. Tannins can provoke negative sensations as shrinking, drawing, or puckering of the epithelium, due to the interactions between salivary proteins and tannins. Nevertheless, in some red wines, astringency can be felt as pleasant mouth-feelings of richness, fullness, mouth-coating, and velvet in the mouth. In Chapter 7, an overview of the research concerned with molecular and sensory mechanisms of astringency is updated, as well as the several methods that have been developed to measure the intensity of the sensation, namely the saliva precipitation index (SPI), based on the binding and precipitation of human saliva with grape and wine tannins.

In Chapter 8, the authors describe the main physicochemical wine instabilities and defects that can appear during wine production. Although the best approach is to prevent their appearance in wines, some of the defects are intrinsic to the grape composition and/or wine production process therefore they must be removed or minimised before bottling. The current research trend is focused on the development of fining agents, additives, or technological solutions with improved specificity that will allow the removal of the defect without changing the other wine characteristics, and at the same time to explore low cost, natural, or renewable materials that will allow a lower environmental impact of the stabilisation process. The preventive measures and treatments, either by using fining agents, additives, or other technological solutions, to avoid them or reduce their impact on wine quality are presented in this chapter. Wine protein instability is a frequent problem in white wine production mainly related to the presence of grape pathogenesis-related (PR) proteins. The development of PR proteins in grapes during ripening and the extraction of PR proteins from grapes into juice can largely affect the concentration of PR proteins in the final wine, which consequently influences wine protein stability. Bentonite fining is the most common method to remove proteins in white wine before bottling, but it can cause the loss of wine volume and the removal of beneficial aromas. Thus, a number of alternative methods have been proposed for their potential to replace bentonite fining and these methods are reviewed in Chapter 9.

Finally, the natural cork stoppers are world known as closures for high-quality wines. Cork is a cellular material with chemical inertia and a set of physical and mechanical properties that provide outstanding performance for in-bottle wine ageing, by combining minute oxygen transfer with sealing, durability, and chemical

**V**

stability, for example, inertness toward the liquid content and along with storage, preventing sensory deterioration. The cork industry has steadily improved production processes and adopted innovative technologies, quality control measures, and certification, regarding the prevention of potential wine taints and off-flavours. Chapter 10 reviews cork stoppers, their properties, and quality and role for wine bottle ageing, tackling their importance for wine aroma and off-flavours while

Summing up the wide range of issues presented in the book covering different research hot topics from winemaking, stabilization and ageing of wines, this book is addressed to quite a broad audience, including both academic researchers and practitioners in halls of wine industries interested in gaining current knowledge. Also, it is heartily recommended to graduate and PhD students in oenology and food science. This book is the result of many collaborating parties and we gratefully acknowledge all the authors who contributed to this book and the IntechOpen team

**Fernanda Cosme, Fernando M. Nunes and Luís Filipe-Ribeiro**

Chemistry Research Centre - Vila Real, (CQ-VR),

Food and Wine Chemistry Laboratory, University of Trás-os-Montes and Alto Douro,

Vila Real, Portugal

presenting the latest advances in cork research.

for this opportunity.

stability, for example, inertness toward the liquid content and along with storage, preventing sensory deterioration. The cork industry has steadily improved production processes and adopted innovative technologies, quality control measures, and certification, regarding the prevention of potential wine taints and off-flavours. Chapter 10 reviews cork stoppers, their properties, and quality and role for wine bottle ageing, tackling their importance for wine aroma and off-flavours while presenting the latest advances in cork research.

Summing up the wide range of issues presented in the book covering different research hot topics from winemaking, stabilization and ageing of wines, this book is addressed to quite a broad audience, including both academic researchers and practitioners in halls of wine industries interested in gaining current knowledge. Also, it is heartily recommended to graduate and PhD students in oenology and food science. This book is the result of many collaborating parties and we gratefully acknowledge all the authors who contributed to this book and the IntechOpen team for this opportunity.

> **Fernanda Cosme, Fernando M. Nunes and Luís Filipe-Ribeiro** Chemistry Research Centre - Vila Real, (CQ-VR), Food and Wine Chemistry Laboratory, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal

**IV**

with alternative products, Chapter 5 deals with the main oenological uses of oak wood chips, the chemical transformations that underlie this practice, and the effect

Port wine is a traditional and worldwide renowned fortified wine produced in the Douro Demarcated Region (DDR) Northeast of Portugal. The quality and uniqueness of the different Port wine styles are highly dependent on the ageing process, namely time, temperature, and oxygen levels. The chemical changes occurring during the Port wine ageing process result in significant changes in colour and aroma according to the different ageing conditions employed for the different Port wine styles. In Chapter 6, a broad and generic overview of the known and potential chemical changes occurring during ageing of Port wine is described, as well as the known chromatic and aroma characteristics of the different Port wine styles and the specific ageing processes, reductive or oxidative way. However, more studies are still needed to deepen our knowledge in order to understand and control the reactions involved in the Port wine ageing process that contribute to its

Astringency is a tactile sensation evoked in the mouth by polyphenols, mainly

binding and precipitation of human saliva with grape and wine tannins.

bentonite fining and these methods are reviewed in Chapter 9.

Finally, the natural cork stoppers are world known as closures for high-quality wines. Cork is a cellular material with chemical inertia and a set of physical and mechanical properties that provide outstanding performance for in-bottle wine ageing, by combining minute oxygen transfer with sealing, durability, and chemical

tannins. Tannins can provoke negative sensations as shrinking, drawing, or puckering of the epithelium, due to the interactions between salivary proteins and tannins. Nevertheless, in some red wines, astringency can be felt as pleasant mouth-feelings of richness, fullness, mouth-coating, and velvet in the mouth. In Chapter 7, an overview of the research concerned with molecular and sensory mechanisms of astringency is updated, as well as the several methods that have been developed to measure the intensity of the sensation, namely the saliva precipitation index (SPI), based on the

In Chapter 8, the authors describe the main physicochemical wine instabilities and defects that can appear during wine production. Although the best approach is to prevent their appearance in wines, some of the defects are intrinsic to the grape composition and/or wine production process therefore they must be removed or minimised before bottling. The current research trend is focused on the development of fining agents, additives, or technological solutions with improved specificity that will allow the removal of the defect without changing the other wine characteristics, and at the same time to explore low cost, natural, or renewable materials that will allow a lower environmental impact of the stabilisation process. The preventive measures and treatments, either by using fining agents, additives, or other technological solutions, to avoid them or reduce their impact on wine quality are presented in this chapter. Wine protein instability is a frequent problem in white wine production mainly related to the presence of grape pathogenesis-related (PR) proteins. The development of PR proteins in grapes during ripening and the extraction of PR proteins from grapes into juice can largely affect the concentration of PR proteins in the final wine, which consequently influences wine protein stability. Bentonite fining is the most common method to remove proteins in white wine before bottling, but it can cause the loss of wine volume and the removal of beneficial aromas. Thus, a number of alternative methods have been proposed for their potential to replace

of their utilization on wine quality.

uniqueness.

**1**

**Chapter 1**

**Abstract**

influence on sensory properties.

acids and stilbenes) families [2].

perception

rings [1].

**1. Introduction**

Phenolic Compounds of Grapes

and Wines: Key Compounds and

*Ruth Hornedo-Ortega, María Reyes González-Centeno,* 

*Kleopatra Chira, Michaël Jourdes and Pierre-Louis Teissedre*

Phenolic compounds are a wide family of thousands of natural bioactives well-known for their overwhelming demonstrated health benefits. Particularly in wines, polyphenols and quality are closely interconnected. Indeed, these compounds possess a critical role due to their contribution to organoleptic wine quality as color, astringency, and bitterness. The profile or the composition of certain polyphenols has been even proposed as an analytical tool for authenticity certification. In this sense, although important progress has been achieved, the understanding of the relationship between the quality of a particular wine and its phenolic composition remains one of the major challenges in enology research. But why? If there is an adjective to define wine, it is "complex." This final complexity of a wine begins with the enormous polyphenolic variability that may be present in grapes influenced by ripening, genetic, or environmental factors, among others. Winemaking process (alcoholic and malolactic fermentation) and wine aging with or without wood contact produce endless reactions giving rise to complex transformations (copigmentation, cycloaddition, polymerization, and oxidation) of polyphenols. This chapter gathers the most relevant information about the composition, variations, and transformations of phenolic compounds from grape to wine including their

**Keywords:** phenolic compounds, grapes, evolution, wine, oak wood, sensory

Grape and wine phenols represent a large family of compounds with a great diversity of chemical structures and degrees of complexity. The term "polyphenols" or "phenolics" is used to define a group of plant secondary metabolites that presents one or more than one hydroxyl (▬OH) groups attached to one or more benzene

Polyphenols are synthetized by phenylpropanoid pathway, being the amino acid phenylalanine (a shikimate pathway product) their common precursor. They can be divided into flavonoid (anthocyanins, flavan-3-ols, flavonols, flavanones, flavanonols, flavones, and chalcones) and non-flavonoid (hydroxybenzoic and hydroxycinnamic

Implications in Sensory Perception
