Fermented beverages, particularly wines, exhibit variable concentrations of organic and phenolic acids, posing challenges in their accurate determination. Traditionally, enzymatic methods or chromatographic analyses, mainly high-performance liquid chromatography (HPLC), have been employed to quantify these compounds individually in the grape must or wine. However, chromatographic analyses face limitations due to the high sugar content in the grape must. Meanwhile, phenolic acids, found in higher quantities in red wines than in white wines, are typically analyzed using HPLC. This study presents a novel method for the quantification of organic acids (OAs), glycerol, and phenolic acids in grape musts and wines. The approach involves liquid-liquid extraction with ethyl acetate, followed by sample derivatization and analysis using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) detection mode. The results indicated successful detection and quantification of all analyzed compounds without the need for sample dilution. However, our results showed that the method of adding external standards was more suitable for quantifying wine compounds, owing to the matrix effect. Furthermore, this method is promising for quantifying other metabolites present in wines, depending on their extractability with ethyl acetate. Fermented beverages, particularly wines, exhibit variable concentrations of organic and phenolic acids, posing challenges in their accurate determination. Traditionally, enzymatic methods or chromatographic analyses, mainly high-performance liquid chromatography (HPLC), have been employed to quantify these compounds individually in the grape must or wine. The approach of this proposed method involves (i) methoximation of wine compounds in a basic medium, (ii) acidification with HCl, (iii) liquid-liquid extraction with ethyl acetate, and (iv) silyl derivatization to analyze samples with gas chromatography-mass spectrometry (GC-MS) in ion monitoring detection mode (SIM). The results indicated successful detection and quantification of all analyzed compounds without the need for sample dilution. However, our results showed that the method of adding external standards was more suitable for quantifying wine compounds, owing to the matrix effect. Furthermore, this method is promising for quantifying other metabolites present in wines, depending on their extractability with ethyl acetate. In other words, the proposed method may be suitable for profiling (targeted) or fingerprinting (untargeted) strategies to quantify wine metabolites or to classify wines according to the type of winemaking process, grape, or fermentation.

This study investigates the impact of inoculating Torulaspora delbrueckii (Td) strains during the initial phase of carbonic maceration (CM) vinification, aiming to enhance the fermentative process and unique characteristics of CM wines. CM is a winemaking technique where whole bunches (without destemming and crushing) are enclosed in tanks filled with carbon dioxide, inducing intracellular fermentation. This study compares the effects of two Td strains on the MLF performance and sensory characteristics of CM wines using both inoculated and spontaneous MLF strategies. Although general physicochemical parameters remained consistent across conditions, organoleptic attributes showed significant differences due to T. delbrueckii presence. T. delbrueckii introduction during CM resulted in wines with increased anthocyanin content and a particular volatile profile. Isoamyl acetate, a key aroma in CM wines, was notably elevated, especially in the TdP strain. Sensory evaluations also revealed distinctions, with TdV wines displaying more pronounced aromas of red fruit, banana, and grass. Regarding MLF, T. delbrueckii presence notably enhanced performance, particularly in spontaneous MLF cases, accelerating fermentation completion. Inoculating the Oenococcus oeni strain OoVP41 also shortened MLF duration. These findings highlight the potential of Td strains to improve MLF efficiency and sensory attributes in CM wines. Using T. delbrueckii strains strategically enables winemakers to optimize MLF and improve sensory profiles, offering an opportunity to produce higher-quality CM wines.

This study investigates the impact of inoculating Torulaspora delbrueckii (Td) strains during the initial phase of Carbonic Maceration (CM) vinification, aiming to enhance the fermentative process and unique characteristics of CM wines. CM is a winemaking technique where whole bunches (without destemming and crushing) are enclosed in tanks filled with carbon dioxide, inducing intracellular fermentation. The study compares the effects of two Td strains on the MLF performance and sensory characteristics of CM wines, using both inoculated and spontaneous MLF strategies. Although general physicochemical parameters remained consistent across conditions, organoleptic attributes showed significant differences due to T. delbrueckii presence. T. delbrueckii introduction during CM resulted in wines with increased anthocyanin content and a particular volatile profile. Isoamyl acetate, a key aroma in CM wines, was notably elevated, especially in the TdP strain. Sensory evaluations also revealed distinctions, with TdV wines displaying more pronounced aromas of red fruit, banana, and grass. Regarding MLF, T. delbrueckii presence notably enhanced performance, particularly in spontaneous MLF cases, accelerating fermentation completion. Inoculating the Oenococcus oeni strain OoVP41 also shortened MLF duration. These findings highlight the potential of Td strains to improve MLF efficiency and sensory attributes in CM wines. Employing T. delbrueckii strains strategically enables winemakers to optimize MLF and improve sensory profiles, offering an opportunity to produce higher-quality CM wines.

The production of white-skin-macerated wines without sulphur dioxide (SO₂) has increased in recent years, although it presents challenges such as uncontrolled alcoholic fermentation (AF) or malolactic fermentation (MLF) and the production of undesirable compounds. Fumaric acid (FA) is being explored as an alternative to SO₂ due to its antimicrobial and acidifying properties. This study evaluated the effects of vinification type (white skin contact vs. conventional white wine) and different treatments: (i) control without additives, (ii) 0.6 g/L FA, and (iii) 40 mg/L SO₂. After AF, MLF was conducted under three conditions: spontaneous fermentation and two inoculated trials with 10⁶ cells/mL of Oenococcus oeni, one without lees and one with 1 g/L lees from AF. Yeast and lactic acid bacteria dynamics during AF were monitored, along with chemical composition, colour, and sensory characteristics of the wines. Results revealed that the development of AF and final wine compositions were influenced by the vinification type and treatment. During MLF, residual FA from the AF was able to delay its progress but was not sufficient to completely inhibit it. The sensory analysis did not reveal significant differences between treatments. Fumaric acid is a viable alternative to SO₂ for managing MLF in high-pH white wines (including those with skin maceration), allowing for lower SO₂ concentrations and enhanced freshness without impacting sensory quality.