Modulation of Geraniol Metabolism During Alcohol Fermentation

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An Overview on Biogenic Amines in Wine

Biogenic amines (BAs) are low molecular weight compounds formed from precursor amino acids, mainly by microbial decarboxylation. The presence of these compounds is important in the food and beverage industry because, in high amounts, they can lead to negative effects on consumers. In this review, we illustrate the critical aspects needed to control the formation of BAs during winemaking and their presence in the final product. Recent biotechnological approaches related to microorganisms and their ability to reduce BAs are illustrated. The current methods used for BA detection and quantification are also presented. These methods are very important to consider, as BAs can serve as markers for the quality assessment of products. The information presented here offers an overview useful for identifying specific parameters and conditions which should be controlled to minimise BA content in wine; knowledge about BAs in foods and beverages has been accumulating in recent years, not only to ensure and improve quality (since BAs have been used as an indicator of spoilage) but especially to guarantee consumer safety due to the potential toxic effects of BAs on humans

Yeast Biodiversity in Vineyard during Grape Ripening: Comparison between Culture Dependent and NGS Analysis

In this study, the evolution of the yeast microflora present on the berry surface, during the ripening of Barbera grapes, was monitored. Sampling was performed in three vineyards located in the “Nizza” Barbera d’Asti DOC zone and different methodologies have been employed. A culture-dependent method based on the identification of strains grown on solid media by ARDRA (Amplified Ribosomal DNA Restriction Analysis) and the D1-D2 domain of ribosomal 26S DNA capillary sequencing was coupled to NGS (Next Generation Sequencing) targeting ITS (Internal Transcribed Sequence) amplicons with the Illumina MiSeq platform. By using culture-dependent techniques, the most frequently detected species was the yeast-like fungus Aureobasidium pullulans, which was dominant in the culturable fraction. Among yeasts, the presence of oligotrophic basidiomycetes such as Cryptococcus spp., Rhodotorula graminis and Sporidiobolus pararoseus was observed at the beginning of ripening. Afterward, upon approaching the harvest, a succession of oxidative or weakly fermentative copiotrophic species occurs, such as Saturnispora diversa, Issatchenkia terricola, Hanseniaspora opuntiae, Starmerella bacillaris and Hanseniaspora uvarum. The massive sequencing revealed a larger number of species, respect to the culture-dependent data. Comparing the two different approaches used in this work, it is possible to highlight some similarities since Aureobasidium, Rhodotorula and Sporobolomyces were detected by both methods. On the contrary, genera Hanseniaspora, Issatchenkia and Saturnispora were revealed by culture-dependent methods, but not by NGS, while Saccharomyces spp. were identified, with low frequency, only by NGS. The integrated application of NGS sequencing and culture-dependent techniques provides a comprehensive view of mycodiversity in the wine-growing environment, especially for yeasts with low abundance

Yeast Biodiversity in Vineyard during Grape Ripening: Comparison between Culture Dependent and NGS Analysis

In this study, the evolution of the yeast microflora present on the berry surface, during the ripening of Barbera grapes, was monitored. Sampling was performed in three vineyards located in the “Nizza” Barbera d’Asti DOC zone and different methodologies have been employed. A culturedependent method based on the identification of strains grown on solid media by ARDRA (Amplified Ribosomal DNA Restriction Analysis) and the D1-D2 domain of ribosomal 26S DNA capillary sequencing was coupled to NGS (Next Generation Sequencing) targeting ITS (Internal Transcribed Sequence) amplicons with the Illumina MiSeq platform. By using culture-dependent techniques, the most frequently detected species was the yeast-like fungus Aureobasidium pullulans, which was dominant in the culturable fraction. Among yeasts, the presence of oligotrophic basidiomycetes such as Cryptococcus spp., Rhodotorula graminis and Sporidiobolus pararoseus was observed at the beginning of ripening. Afterward, upon approaching the harvest, a succession of oxidative or weakly fermentative copiotrophic species occurs, such as Saturnispora diversa, Issatchenkia terricola, Hanseniaspora opuntiae, Starmerella bacillaris and Hanseniaspora uvarum. The massive sequencing revealed a larger number of species, respect to the culture-dependent data. Comparing the two different approaches used in this work, it is possible to highlight some similarities since Aureobasidium, Rhodotorula and Sporobolomyces were detected by both methods. On the contrary, genera Hanseniaspora, Issatchenkia and Saturnispora were revealed by culture-dependent methods, but not by NGS, while Saccharomyces spp. were identified, with low frequency, only by NGS. The integrated application of NGS sequencing and culture-dependent techniques provides a comprehensive view of mycodiversity in the wine-growing environment, especially for yeasts with low abundance

An Overview on <em>Saccharomyces cerevisiae</em> Indigenous Strains Selection Methods

From the fundamental studies of Louis Pasteur in the XIX century to the current genomic analysis, the essential role of microorganisms in winemaking industry is well recognised. In the last decades, selected Saccharomyces cerevisiae strains with excellent fermentative behaviour have been widely commercialised in form of active dry yeasts. Currently, the production of organic and “natural” wines represents a new economically relevant trend in the wine sector. Based on this market demand, the use of industrial yeast starter could be perceived as non-organic practice and then, rejected. However, in order to preserve wines sensory quality, healthiness, and to avoid organoleptic defects given by undesirable microorganisms, the “yeast factor” (S. cerevisiae or non-Saccharomyces) cannot be ignored. The purpose of this chapter is to describe the methods of selection of wine yeasts focusing the attention on indigenous S. cerevisiae strains. In fact, the use of ecotypic yeasts may represent a good compromise between the needs of microbiologically controlled fermentation and a modern vision of wine as natural expression of its “terroir”, also from the microbiological point of view

Application of dry-ice blasting for barrels treatment

The main aim of this work was to test a dry-ice basting method to regenerate the barriques in order to prolong their life. In addition, this treatment for barrels can also represent an alternative to the use of sulfur dioxide for the barrique sanitization, in line with the guidelines of oenological practices for sustainable development proposed by the OIV (International Organization of Vine and Wine) (sustainable development, food security: reduction the content of sulfites in wine). The effect of the blasting with dry ice for the treatment of barrique has been studied from a microbiological and sensory point of view. Microbiological analyses were carried out using wine contaminated with Brettanomyces and Lactobacillus; results showed a reduction of contaminant of 98–100%. Finally, it was evaluated the impact of this treatment on the sensory profile of wine. In this regard the wine aged in a barrique dry-ice blasted was compared with a wine aged in a barrique treated with sulfur dioxide. From the sensory analysis emerged that the dry-ice blasting treatment can regenerate the barriques, this confers to the wine increased notes of vanilla and boisé. The benefits that derive from the use of this method are: a good sanitization of the barrel, a positive impact on the organo- leptic characteristics of the wine and the ability to regenerate and reuse a barrel, with a positive effect on sustainability

Application of dry-ice blasting for barrels treatment

The main aim of this work was to test a dry-ice basting method to regenerate the barriques in order to prolong their life. In addition, this treatment for barrels can also represent an alternative to the use of sulfur dioxide for the barrique sanitization, in line with the guidelines of oenological practices for sustainable development proposed by the OIV (International Organization of Vine and Wine) (sustainable development, food security: reduction the content of sulfites in wine). The effect of the blasting with dry ice for the treatment of barrique has been studied from a microbiological and sensory point of view. Microbiological analyses were carried out using wine contaminated with Brettanomyces and Lactobacillus; results showed a reduction of contaminant of 98–100%. Finally, it was evaluated the impact of this treatment on the sensory profile of wine. In this regard the wine aged in a barrique dry-ice blasted was compared with a wine aged in a barrique treated with sulfur dioxide. From the sensory analysis emerged that the dry-ice blasting treatment can regenerate the barriques, this confers to the wine increased notes of vanilla and boisé. The benefits that derive from the use of this method are: a good sanitization of the barrel, a positive impact on the organo- leptic characteristics of the wine and the ability to regenerate and reuse a barrel, with a positive effect on sustainability