Graham H. Fleet – författare

Cocoa and coffee beans are some of the most traded agricultural commodities on international markets. Combined, they provide raw materials for a global industry valued in excess of $250 billion. Despite this, few people know that microorganisms and microbial fermentation play key roles in their production and can have major impacts on product quality, safety, and value.Cocoa and Coffee Fermentations explores the scientific principles behind cocoa and coffee fermentation. The book covers botanical and production backgrounds, methods of bean fermentation and drying, microbial ecology and activities of fermentation, the biochemistry of fermentation, product quality and safety, and waste utilization. The book aims to optimize cocoa and coffee processing based on scientific evidence to enhance traditional processing methods that often give rise to inefficiencies and inconsistencies in product quality. It also aims to provide a better understanding of the complex microbial ecology in cocoa and coffee fermentations which involve interactions between species of yeasts, bacteria, and filamentous fungi.Cocoa and Coffee Fermentations hopes to inspire further research linking the microbiology and biochemistry of cocoa and coffee bean fermentations with the development of better controlled fermentations, implementation of quality assurance programs, and ultimately improvement of the sensory attributes of the final product.

It is well established that certain strains of yeasts are suitable for transforming grape sugars into alcohol, while other yeast strains are not suitable for grape fermentations. Recent progress has clearly demonstrated that the sensory profile of a wine is characteristic of each vine cultivated, and the quality and technological characteristics of the final product varies considerably due to the strains which have performed and/or dominated the fermentation process. Because of their technological properties, wine yeast strains differ significantly in their fermentation performance and in their contribution to the final bouquet and quality of wine, such as useful enzymatic activities and production of secondary compounds related both to wine organoleptic quality and human health. The wine industry is greatly interested in wine yeast strains with a range of specialized properties, but as the expression of these properties differs with the type and style of wine to be made, the actualtrend is in the use of selected strains, which are more appropriate to optimize grape quality. Additionally, wine quality can be influenced by the potential growth and activity of undesirable yeast species, considered spoilage yeasts, which cause sluggish and stuck fermentation and detrimental taste and aroma in the wine.

As a group of microorganisms, yeasts have an enormous impact on food and bev- age production. Scientific and technological understanding of their roles in this p- duction began to emerge in the mid-1800s, starting with the pioneering studies of Pasteur in France and Hansen in Denmark on the microbiology of beer and wine fermentations. Since that time, researchers throughout the world have been engaged in a fascinating journey of discovery and development – learning about the great diversity of food and beverage commodities that are produced or impacted by yeast activity, about the diversity of yeast species associated with these activities, and about the diversity of biochemical, physiological and molecular mechanisms that underpin the many roles of yeasts in food and beverage production. Many excellent books have now been published on yeasts in food and beverage production, and it is reasonable to ask the question – why another book? There are two different approaches to describe and understand the role of yeasts in food and beverage production. One approach is to focus on the commodity and the technology of its processing (e. g. wine fermentation, fermentation of bakery products), and this is the direction that most books on food and beverage yeasts have taken, to date. A second approach is to focus on the yeasts, themselves, and their bi- ogy in the context of food and beverage habitats.