Dimitris Tsaltas

By Despina Bozoudi and Dimitris Tsaltas

Grape microbiome is the source of a vastly diverse pool of filamentous fungi, yeast and bacteria that will play a coordinated role for the quality of the produced wines. In recent times, the significance of this pool of microorganisms with a long list of studies of the microbial ecology of grape berries of different geographical origin, cultural practices, grape varieties and climatic conditions has been acknowledged. Similarly, the ongoing microbial evolution of must fermentations has been fully uncovered. All these ecology studies, along with detailed metabolic studies and sensorial characterisations of the produced wines, led to the suggestion of the microbial terroir. These new concepts are today leading worldwide research efforts to the production of unique wines, preserving their historical identity and verifying their quality and geographical origin. This chapter is a quick but thorough and up-to-date review of how autochthonous microbiota highlight the terroir in wines, a comparison of commercial and wild yeast strains and how this biodiversity has been explored. Moreover, technological, physiological and oenological selection criteria will be under consideration. At the end, the positive and negative aspects of wild vinifications, the technological problems of wild strains and some suggestions for the future in starter cultures will be presented.

Part of the book: Grape and Wine Biotechnology

By Michalakis Christoforou, Michael Orford and Dimitris Tsaltas

The phylum of Nematoda is a species‐rich taxonomic group in abundant numbers across a wide range of habitats, including plant and animal pathogens, as well as good environmental health indicators. Morphological observations are of low throughput and more importantly have problems with their discriminatory capacity, particularly at the species level. For these reasons, diagnostic tools are of paramount importance for all fields of human, animal and plant nematology as well as for environmental studies in water and soil. Accurate, fast and low‐cost methodologies are required in order to identify and quantify the population of nematodes in samples from various sources. Scientists in basic research as well as in routine application fields need to have tools for resolving these identification obstacles. Their decisions can be human‐, animal‐ or plant‐health related, while many times legally committing. As a result, applicable and accredited methods are required and should be readily available in a common routine lab or in the field of battle or at border control agencies. This chapter aims to inform with the most current information on the available tools for nematode diagnostics, their positives and negatives and hints about the trends in the field and suggestions for those who would like to pursue further this field of biotechnology as researchers or simple users.

Part of the book: Nematology

By Minas Mina and Dimitrios Tsaltas

Organoleptic characteristics of wine, especially, the spectrum that is defined as flavour and aroma, are the most important parameters for assessing the quality of wine. The origin of these characteristics comes for four main sources: grapes, vinification, maturation and ageing. The final concentrations of various odour-active components (OAC) are highly depended on the yeast during fermentation. The major OAC that are formed during fermentation are volatile substances like esters, higher alcohols and carbonyl compounds. Decoding the origin and contribution of these OAC, the modern winemaker can direct and manipulate the yeast during fermentation on his benefit. These compounds are originated from the secondary metabolism of the yeast, understanding the role of the key parameters during fermentation influencing the OAC formation like temperature, yeast assimilable nitrogen (YAN) and suspended solids is vital for the final organoleptic characteristics of wine.

Part of the book: Yeast

By Dimitrios Anagnostopoulos, Despina Bozoudi and Dimitrios Tsaltas

The table olive is considered to be a traditional fermented vegetable in the Mediterranean countries and its production and consumption is recently spreading all around the world. The presence of yeasts is very important during olive fermentation due to their double role. On one hand, yeasts maintain desirable biochemical activities (lipase, esterase, β-glucosidase, catalase, production of killer factors, etc.) with essential technological applications in this fermented vegetable. On the other hand, spoilage activity may be shown. However, recent studies have reported that yeasts coming from table olives would be a new source of potential probiotics. Indeed, many yeast species found in table olive processing, have been reported to demonstrate such properties. Thus, starter cultures technology will play significant role, not only in olive fermentation by controlling the safety and the quality of the final product, but also in consumer’s health.

Part of the book: Yeast

By Dimitrios A. Anagnostopoulos, Eleni Kamilari and Dimitrios Tsaltas

Wine is the alcoholic beverage which is the product of alcoholic fermentation, usually, of fresh grape must. Grape microbiome is the source of a vastly diverse pool of filamentous fungi, yeast, and bacteria, the combination of which plays a crucial role for the quality of the final product of any grape must fermentation. In recent times, the significance of this pool of microorganisms has been acknowledged by several studies analyzing the microbial ecology of grape berries of different geographical origins, cultural practices, grape varieties, and climatic conditions. Furthermore, the microbial evolution of must during fermentation process has been overstudied. The combination of the microbial evolution along with metabolic and sensorial characterizations of the produced wines could lead to the suggestion of the microbial terroir. These aspects are today leading to open a new horizon for products such as wines, especially in the case of PDO-PGI products. The aims of this review is to describe (a) how the microbiome communities are dynamically differentiated during the process of fermentation from grape to ready-to-drink wine, in order to finalize each wine’s unique sensorial characteristics, and (b) whether the microbiome could be used as a fingerprinting tool for geographical indication, based on high-throughput sequencing (HTS) technologies. Nowadays, it has been strongly indicated that microbiome analysis of grapes and fermenting musts using next-generation sequencing (NGS) could open a new horizon for wine, in the case of protected designation of origin (PDO) and protected geographical indication (PGI) determination.

Part of the book: Advances in Grape and Wine Biotechnology