**Chapter 9 165**

From Food Waste to Volatile Fatty Acids towards a Circular Economy *by Mónica Carvalheira and Anouk F. Duque*

Preface

*Fermentation - Processes, Benefits and Risks* deals with the topic of fermentation, a process by which carbohydrates are converted to alcohol or organic acids under anaerobiosis using microorganisms (bacteria or yeasts). It is divided into two sections: "Fermentation Processes in Agriculture and Industry" and "Food Fermentations."

The first section includes four chapters that introduce the role of fermentation in

In Chapter 1, the authors introduce fermentation as a multi-disciplinary concept in agriculture, exploring the fermentative processes in the nutrition system of ruminants and unraveling how fermentation processes occur in the soil. In Chapters 2 to 4, the authors focus on distinct industrial applications of different fermentation processes, including biopharmaceutical (Chapter 2), biocatalysis of enzymes (Chapter 3), and sustainable biomass processing via an integrated

The second section contains five chapters on different aspects of fermented foods, which comprise very diverse food products and beverages with a long history of worldwide importance for human nutrition, health, and the economy. The main groups of fermented foods include cereals (bread and sake); vegetables, fruits, and legumes (table olives, pickles, and vinegar); milk (cheese, yogurt, and kefir); meat and meat products (ham and sausages); fish products (anchovies and herring); and alcoholic beverages (wine and beer). A huge diversity of indigenous microorganisms, mostly bacteria and yeasts, is associated with this enormous variety of fermented foods. They differ not only in the used raw materials, and corresponding final products, but also in their distinct fermentative behavior. The microbial safety of these fermented food products is, however, threatened by the potential presence of foodborne pathogens. These may be harmful per se, but also due to the toxins and other secondary metabolites they release, such as mycotoxins or biogenic amines. To assure the quality and safety of fermented foods, different approaches are needed to successfully control the indigenous microbiota and conduct fermentation, for example, using starter cultures, but also to effectively

In Chapter 5, the authors review the fermentation of milk from distinct origins, namely bovine, non-bovine, and vegetable, discussing the potential benefits and drawbacks of each of them. Chapter 6 gives us some insights into the microbiota of traditionally processed cheeses, according to their different compositions and production technologies. Chapter 7 deals with the fermentation of cocoa beans, a crucial stage in the post-harvest processing of cocoa that has not been studied extensively. Chapter 8 explores ohmic fermentation of coffee as an innovative approach to imprint a distinctive aroma profile and improve the aroma quality of coffee. In Chapter 9, the authors show how added-value compounds, such as volatile fatty acids, can be produced by biotechnological processes, namely anaerobic fermentation, valorizing food waste as a carbon source for fermentation towards a

agriculture, as well as the various industrial applications of fermentation.

biorefinery approach (Chapter 4).

implement innovative preservation methodologies.

circular economy.
