Yeast biomass is considered a low-cost material that can be successfully used for the biosorption of metal ions from aqueous solution, due to its structural characteristics. This study evaluates the biosorptive performance of Saccharomyces cerevisiae in the biosorption of Co(II), Zn(II) and Cu(II) ions from aqueous media in batch mono-component systems. The influence of solution pH, biosorbent dose, contact time, temperature and initial metal ions concentration was examined step by step, to obtain the optimal conditions for biosorption experiments. Maximum uptake efficiency for all metal ions on this biosorbent was obtained at: pH = 5.0, 4.0 g biosorbent/L, room temperature of 23 °C, and a contact time of 60 min, and these were considered optimal. The equilibrium results were analyzed using Langmuir, Freundlich and Dubinin–Radushkevich isotherm models, while for the modeling of the kinetics data, three models (pseudo-first order, pseudo-second order and intra-particle diffusion) were used. Dubinin–Radushkevich isotherm model and the pseudo-second order model showed the best fit with the experimental data obtained at biosorption of Co(II), Zn(II) and Cu(II) ions on Saccharomyces cerevisiae. Both maximum biosorption capacities and pseudo-second rate constants follow the order: Co(II) > Zn(II) > Cu(II), suggesting that the structural particularities of metal ions are important in the biosorption processes. Based on the obtained equilibrium and kinetic parameters, the biosorption mechanism is analyzed and the possible applications are emphasized.

Organic acids represent naturally occurring compounds that are found in many types of food and beverages, with important functions in defining products’ final quality. Their proportions in wine are dependent on grape composition and winemaking conditions (temperature, pH levels, oxygen, and carbon dioxide concentration). Therefore, this article studied the influence of different fermentation conditions (200 hL tanks vs. 50 L glass demijohns) and various yeasts on the evolution of the main organic acids during alcoholic fermentation of “Aligoté” wines. The fermentation lasted 22 days and samples were collected daily. Laboratory analyses were quantified according to the International Organization of Vine and Wine recommendations. High-performance liquid chromatography for the identification and quantification of organic acids was used. The data showed the important effect of winemaking conditions on sugar consumption, density or acidity values, and sensory characteristics. Significant differences in organic acid concentrations (especially for tartaric acid) were obtained for all variants, depending on the fermentation conditions, inoculated yeast and the sampling moment. The quantities of most of the identified organic acids were generally significantly increased when glass vessels were used, compared to those fermented in tanks. Most organic acids concentrations were favored by lower pH and showed higher values at lower temperatures.

The occurrence of aroma constituents in sparkling wines, with direct impact on their organoleptic characteristics, is affected by several factors, for example the base-wine particularities, grapes cultivar conditions, inoculated yeasts, the aging stage, and wine-making practices. This study evaluated the influence of different four commercial yeasts (IOC FIZZ™, IOC DIVINE™, LEVULIA CRISTAL™, and IOC 18-2007™) on the volatile composition of experimental sparkling wines. For this, five sparkling wines variants from the Muscat Ottonel grape variety were obtained. The base-wine was obtained through reverse osmosis and had a predetermined alcoholic concentration (10.5% vol.). In order to fulfill the proposed purpose, the experimental sparkling wines were characterized by the physical–chemical parameters (according to International Organization of Vine and Wine methods of analysis), volatile fraction (using gas-chromatography coupled with mass spectrometry technique), and sensory descriptors. Data showed a key impact on the concentration of the volatile constituents (p < 0.05), depending on the type of inoculated yeast for the second fermentation. Regarding the sensory analysis, important differences can be observed due to the type of inoculated yeast. Only a minor influence on the physical–chemical parameters was registered.

Sparkling wine producing and consumption are in constant increase in the last decade and show no sign of slowing. Prior consumption, origin, grape variety, occasion, price and sensorial perception are factors that typically influence wine consumers’ purchasing and consumption behavior. The presence of volatile compounds in sparkling wines, with direct impact on their organoleptic characteristics, is influenced by several factors, such as the base-wine characteristics, grapes cultivar conditions, the used yeasts, the aging stage or wine-making practices. For this study, five sparkling wines variants from Muscat Ottonel grape variety were obtained. For the experimental samples, the grapes were processed by applying secondary fermentation in bottles. The base-wine was obtained through reverse osmosis and had a predetermined alcoholic concentration (10.5 % vol.). This study aimed to analyze the influence of different commercial yeasts (IOC FIZZ™, IOC DIVINE™, LEVULIA CRISTAL™, IOC 18-2007™) on the volatile composition of experimental sparkling wines. The obtained sparkling wines were characterized by the physical-chemical parameters (according to OIV methods of analysis) and volatile fraction (using gas-chromatography). Data showed an important impact on the concentration of the volatile compounds (p < 0.05), depending on the type of inoculated yeast for the second fermentation and only a minor influence on the physical-chemical parameters was registered.

The biochemistry and physiology of raw material, the metabolism of microorganisms, and the methods used for processing and storage can affect the stability of wines. Due to the antimicrobial action of sulfur dioxide and dimethyl dicarbonate, the aim of this study is to determine the optimal treatment protocol to maintain the physico–chemical and microbiological stability of white wines with high residual sugar. Thus, the present research focuses on analyzing the influence of both treatments, combined or separate, on 45 wine samples obtained from a blend of Muscat Ottonel and Fetească Regală grape varieties, where different doses of 6% aqueous SO₂ solution (40, 80, and 160 mg/L) and dimethyl bicarbonate (0, 100, and 200 mg/L) were used. In order to assess the ability of dimethyl dicarbonate to suppress microorganisms, varying concentrations of Brettanomyces bruxellensis and Schizosaccharomyces pombe yeasts were inoculated (0, 30, 100 CFU/mL wine). The results indicate that, while sulfur dioxide cannot be entirely substituted in wines, both treatments can effectively lower or inhibit the activity of spoilage microorganisms. For the wines’ physico–chemical and microbiological stability, the treatment that used the synergistic force of sulfur dioxide (160 mg/L) and dimethyl dicarbonate (200 mg/L wine) performed the best.

Melatonin is commonly found in various fruits, juices, and some fermented beverages. Its concentration in wine is influenced by soil properties, climatic factors, and yeast activity. Even if it is found in fermented beverages in relatively low proportions, melatonin still holds significant nutritional value, giving anti-aging properties, anti-inflammatory actions, and antidepressant effects. In this context, this article focuses on evaluating the impact of different Saccharomyces and non-Saccharomyces yeast species on the formation of melatonin and its contribution to wines’ total antioxidant capacity. Considering that the antioxidant activity of wine is usually related to the content of phenolic compounds, ten such compounds were analyzed. The evaluation of bioactive compounds was performed using high-performance liquid chromatography (HPLC) coupled with mass spectrometry. The total antioxidant capacity of wine samples was evaluated by the ABTS⁺ method. The administration of bâtonnage products increased the efficiency of non-Saccharomyces yeasts. The mixtures of Saccharomyces and non-Saccharomyces yeasts generated higher values for melatonin. The results confirm a significant impact from the grape variety and the specific yeast strains on the melatonin concentration. Also, a strong dependence between antioxidant activity and melatonin levels was observed. Given the limited existing studies on the presence of melatonin in wines, new perspectives are needed for future exploration and understanding.