SUSTAINABILITY IN WINEMAKING FIRST PART: USE OF METSCHNIKOWIA PULCHERRIMA FOR THE BIOCONTROL OF WINES WITH LOW SULPHITES A wide variety of non-Saccharomyces yeast are present on the grape surface and involved in spontaneous fermentation process. These yeasts are often associated with stuck fermentations and are considered spoilage yeasts. To control these yeasts in modern oenology, sulfur dioxide (SO2) is widely used as an antimicrobial agent, which thanks to its low cost and certified effectiveness is the best solution to control microbial growth. During the last few years the attention was focused on the use of non-Saccharomyces yeast as biocontrol agent to decrease the use of (SO2). In this regard, the use of non-Saccharomyces yeasts in wine fermentation could be a strategy to reduce the use of SO2 and at the same time improve the aroma profile of wine. Numerous studies focused on bio-control activity of Metschnikowia pulcherrima. The results showed that the antimicrobial activity would not be linked to a protein, as for the killer factor, but to the presence of an acid precursor of the pigment responsible of coloration of the colonies. Some studies highlighted that this activity don’t affect the growth of S. cerevisiae but showed an inhibition against spoilage yeasts such as Brettanomyces / Dekkera spp., Hanseniaspora spp., and Pichia spp . In this work, the use of M. pulcherrima and S. cerevisiae in sequential fermentations was evaluated to produce wines with low sulphite content, analytically correct and having a characteristic aromatic bouquet. The fermentation trials were carried out in cellar using Verdicchio grape juice. The tanks were inoculated with M. pulcherrima for the first 48 hours. After 48 hours of fermentation, the S. cerevisiae strain was inoculated to complete the fermentation. The results showed that in the absence of added SO2, the concentration of indigenous microorganisms was significantly reduced when compared with the control thesis without inoculation of M. pulcherrima. In conclusion, the use of M. pulcherrima in sequential fermentation with S.cerevisiae is a suitable strategy to obtain wines with a low SO2 content while maintaining a high quality level. Keywords: Metschnikowia pulcherrima, wine, sequential fermentation, sulfure dioxide SECOND PART: REDUCTION OF ETHANOL CONTENT IN WINE In the last few decades, the increase of ethanol in wine, due to global climate change and consumers choice is one of the main concerns in winemaking. One of the most promising approaches in reducing the ethanol content in wine is the use of non-Saccharomyces yeasts in co-fermentation or sequential fermentation with Saccharomyces cerevisiae. In this regard, we evaluate the use of Starmerella bombicola and S. cerevisiae in sequential fermentation under aeration condition with the aim of reducing the ethanol content with valuable analytical profile. After a preliminary screening in synthetic grape juice, bench-top fermentation trials were conducted in natural grape juice by evaluating the aeration condition (20 mL/L/min during the first 72 h) on ethanol reduction and on the analytical profile of wines. The results showed that S. bombicola/S. cerevisiae sequential fermentation under aeration condition determined an ethanol reduction of 1.46% (v/v) compared with S. cerevisiae pure fermentation. Aeration condition did not negatively affect the analytical profile of sequential fermentation S. bombicola/S. cerevisiae particularly an overproduction of volatile acidity and ethyl acetate. On the other hand, these conditions strongly improved the production of glycerol and succinic acid that positively affect the structure and body of wine.
LA SOSTENIBILITÀ IN VITICOLTURA PRIMA PARTE: UTILIZZO DI METSCHNIKOWIA PULCHERRIMA PER IL BIOCONTROLLO DEI VINI A BASSO CONTENUTO DI SOLFITi Sulla superficie dell'uva è presente un'ampia varietà di lieviti non Saccharomyces coinvolti nel processo di fermentazione spontanea. Questi lieviti sono spesso associati ad arresti di fermentazione e sono considerati lieviti deterioranti. Per il controllo di questi lieviti nella moderna enologia, viene ampiamente utilizzato come agente antimicrobico l'anidride solforosa (SO2), che grazie al suo basso costo e alla sua efficacia certificata è la migliore soluzione per controllare la crescita microbica. Negli ultimi anni l'attenzione si è concentrata sull'uso di lievito non-Saccharomyces come agente di biocontrollo per diminuire l'uso di (SO2). A questo proposito, l'uso di lieviti non-Saccharomyces nella fermentazione del vino potrebbe essere una strategia per ridurre l'uso di SO2 e allo stesso tempo migliorare il profilo aromatico del vino. Numerosi studi si sono concentrati sull'attività di biocontrollo di Metschnikowia pulcherrima. I risultati hanno mostrato che l'attività antimicrobica non sarebbe legata ad una proteina, come per il fattore killer, ma alla presenza di un precursore acido del pigmento responsabile della colorazione delle colonie. Alcuni studi hanno evidenziato che questa attività non influisce sulla crescita di S. cerevisiae ma ha mostrato un'inibizione nei confronti di lieviti deterioranti come Brettanomyces / Dekkera spp., Hanseniaspora spp. e Pichia spp. Parole chiave: Metschnikowia pulcherrima, vino, fermentazione sequenziale, anidride solforosa SECONDA PARTE: RIDUZIONE DEL CONTENUTO DI ETANOLO NEL VINO Negli ultimi decenni, l'aumento dell'etanolo nel vino, dovuto al cambiamento climatico globale e alle scelte dei consumatori, è una delle principali preoccupazioni nella vinificazione. Uno degli approcci più promettenti per ridurre il contenuto di etanolo nel vino è l'uso di lieviti non-Saccharomyces in co-fermentazione o fermentazione sequenziale con Saccharomyces cerevisiae. A questo proposito, valutiamo l'uso di Starmerella bombicola e S. cerevisiae in fermentazione sequenziale in condizioni di aerazione con l'obiettivo di ridurre il contenuto di etanolo con un prezioso profilo analitico. Dopo uno screening preliminare su mosto sintetico, sono state condotte prove di fermentazione al banco nel succo d'uva naturale valutando la condizione di aerazione (20 mL/L/min durante le prime 72 ore) sulla riduzione dell'etanolo e sul profilo analitico dei vini. I risultati hanno mostrato che S. bombicola/S. cerevisiae la fermentazione sequenziale in condizioni di aerazione ha determinato una riduzione di etanolo dell'1,46% (v/v) rispetto alla fermentazione pura di S. cerevisiae. Le condizioni di aerazione non hanno influenzato negativamente il profilo analitico della fermentazione sequenziale S. bombicola/S. cerevisiae in particolare una sovrapproduzione di acidità volatile e acetato di etile. D'altra parte, queste condizioni hanno migliorato notevolmente la produzione di glicerolo e acido succinico che influiscono positivamente sulla struttura e sul corpo del vino.
SUSTAINABILITY IN WINEMAKING: ROLE OF NON-SACCHAROMYCES YEASTS / Galli, Edoardo. - (2023 Mar 16).
SUSTAINABILITY IN WINEMAKING: ROLE OF NON-SACCHAROMYCES YEASTS
GALLI, EDOARDO
2023-03-16
Abstract
SUSTAINABILITY IN WINEMAKING FIRST PART: USE OF METSCHNIKOWIA PULCHERRIMA FOR THE BIOCONTROL OF WINES WITH LOW SULPHITES A wide variety of non-Saccharomyces yeast are present on the grape surface and involved in spontaneous fermentation process. These yeasts are often associated with stuck fermentations and are considered spoilage yeasts. To control these yeasts in modern oenology, sulfur dioxide (SO2) is widely used as an antimicrobial agent, which thanks to its low cost and certified effectiveness is the best solution to control microbial growth. During the last few years the attention was focused on the use of non-Saccharomyces yeast as biocontrol agent to decrease the use of (SO2). In this regard, the use of non-Saccharomyces yeasts in wine fermentation could be a strategy to reduce the use of SO2 and at the same time improve the aroma profile of wine. Numerous studies focused on bio-control activity of Metschnikowia pulcherrima. The results showed that the antimicrobial activity would not be linked to a protein, as for the killer factor, but to the presence of an acid precursor of the pigment responsible of coloration of the colonies. Some studies highlighted that this activity don’t affect the growth of S. cerevisiae but showed an inhibition against spoilage yeasts such as Brettanomyces / Dekkera spp., Hanseniaspora spp., and Pichia spp . In this work, the use of M. pulcherrima and S. cerevisiae in sequential fermentations was evaluated to produce wines with low sulphite content, analytically correct and having a characteristic aromatic bouquet. The fermentation trials were carried out in cellar using Verdicchio grape juice. The tanks were inoculated with M. pulcherrima for the first 48 hours. After 48 hours of fermentation, the S. cerevisiae strain was inoculated to complete the fermentation. The results showed that in the absence of added SO2, the concentration of indigenous microorganisms was significantly reduced when compared with the control thesis without inoculation of M. pulcherrima. In conclusion, the use of M. pulcherrima in sequential fermentation with S.cerevisiae is a suitable strategy to obtain wines with a low SO2 content while maintaining a high quality level. Keywords: Metschnikowia pulcherrima, wine, sequential fermentation, sulfure dioxide SECOND PART: REDUCTION OF ETHANOL CONTENT IN WINE In the last few decades, the increase of ethanol in wine, due to global climate change and consumers choice is one of the main concerns in winemaking. One of the most promising approaches in reducing the ethanol content in wine is the use of non-Saccharomyces yeasts in co-fermentation or sequential fermentation with Saccharomyces cerevisiae. In this regard, we evaluate the use of Starmerella bombicola and S. cerevisiae in sequential fermentation under aeration condition with the aim of reducing the ethanol content with valuable analytical profile. After a preliminary screening in synthetic grape juice, bench-top fermentation trials were conducted in natural grape juice by evaluating the aeration condition (20 mL/L/min during the first 72 h) on ethanol reduction and on the analytical profile of wines. The results showed that S. bombicola/S. cerevisiae sequential fermentation under aeration condition determined an ethanol reduction of 1.46% (v/v) compared with S. cerevisiae pure fermentation. Aeration condition did not negatively affect the analytical profile of sequential fermentation S. bombicola/S. cerevisiae particularly an overproduction of volatile acidity and ethyl acetate. On the other hand, these conditions strongly improved the production of glycerol and succinic acid that positively affect the structure and body of wine.File | Dimensione | Formato | |
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