Oenological potential of extracts from winery and cooperage by-products in combination with colloidal silver as natural substitutes to sulphur dioxide

Evaluation of grape stems and grape stem extracts for sulfur dioxide replacement during grape wine production

Sulfur dioxide (SO₂), the main preservative in wine, may affect the sensory properties of the wines, as well as cause allergic reactions and headaches in sensitive people. The aim of this work was to evaluate the replacement of SO₂ in Tempranillo wines with Mazuelo grape stem products. Five Tempranillo red wines were elaborated: positive control (60 mg/L SO₂); negative control with no preservatives; Mazuelo extract (200 mg/L); Mazuelo extract combined with SO₂ (100 mg/L + 20 mg/L); and Mazuelo stem (400 mg/L). The oenological parameters, antioxidant capacity, total phenolic (TP), total flavonoids (TF) and total anthocyanins (TA) contents were determined. Additionally, individual phenols were analyzed by HPLC-DAD-FLD. The spectrophotometric analyses showed that the wines had similar antioxidant capacities and concentrations of TP and TF. However, TA was more affected by the lack of SO₂ as anthocyanins presented higher concentrations in positive control samples. The concentrations of individual phenols followed a similar path in all samples. Wines containing sulfites were more similar than the other treatments. However, these similarities were not reflected on the sensory analysis performed, as triangle test did not show differences between the wine with extract addition and the positive control wine. Therefore, Mazuelo stem extract could be a possible strategy for SO₂ replacement. Nevertheless, further studies are necessary to confirm the potential of grape stem extracts as wine preservative.

Plant- and Animal-Based Antioxidants' Structure, Efficacy, Mechanisms, and Applications: A Review

Antioxidants are compounds that normally prevent lipid and protein oxidation. They play a major role in preventing many adverse conditions in the human body, including inflammation and cancer. Synthetic antioxidants are widely used in the food industry to prevent the production of adverse compounds that harm humans. However, plant- and animal-based antioxidants are more appealing to consumers than synthetic antioxidants. Plant-based antioxidants are mainly phenolic compounds, carotenoids, and vitamins, while animal-based antioxidants are mainly whole protein or the peptides of meat, fish, egg, milk, and plant proteins. Plant-based antioxidants mainly consist of aromatic rings, while animal-based antioxidants mainly consist of amino acids. The phenolic compounds and peptides act differently in preventing oxidation and can be used in the food and pharmaceutical industries. Therefore, compared with animal-based antioxidants, plant-based compounds are more practical in the food industry. Even though plant-based antioxidant compounds are good sources of antioxidants, animal-based peptides (individual peptides) cannot be considered antioxidant compounds to add to food. However, they can be considered an ingredient that will enhance the antioxidant capacity. This review mainly compares plant- and animal-based antioxidants’ structure, efficacy, mechanisms, and applications.

Effects of the pre-fermentative addition of chitosan on the nitrogenous fraction and the secondary fermentation products of SO2 -free red wines

BACKGROUND

Different red winemaking were carried out to evaluate the effects of the prefermentative addition of chitosan, as an alternative to the use of SO₂ , on the secondary products of alcoholic fermentation, yeast available nitrogen (YAN), biogenic amines and ethyl carbamate.

RESULTS

The wines made with chitosan presented higher total acidity and higher content of tartaric and succinic acids than those made only with SO₂ . The use of chitosan in winemaking resulted in wines with higher glycerol and diacetyl content without increasing the concentration of ethanol, acetic acid, acetaldehyde or butanediol. YAN was lower in wines made with chitosan, which may mean an advantage for the microbial stability of the wines. Furthermore, the use of chitosan at the beginning of alcoholic fermentation did not increase the concentration of biogenic amines or the formation of ethyl carbamate in SO₂ -free red wines.

CONCLUSION

The total or partial substitution of SO₂ for chitosan at the beginning of the alcoholic fermentation gives rise to quality red wines without negatively affecting their nitrogen fraction or their very important secondary fermentation products such as acetic acid or acetaldehyde. © 2020 Society of Chemical Industry.

Impact of oenological antioxidant substances on the formation of 1-hydroxyethyl radical and phenolic composition in SO2 free red wines

BACKGROUND

Different natural substances, chitosan, inactive dry yeasts and freeze-dried aqueous extracts from two wine industry by-products (stems and shoots) were used in red winemaking as possible alternatives to SO₂ . The resistance to oxidation of wines was evaluated by electron paramagnetic resonance. The phenolic composition of wines was analyzed by high-performance liquid chromatography-diode array detection/electrospray ionization mass spectrometry, antioxidant activity was determined by DPPH (1,1-diphenyl-2-picrylhydrazyl radical) and ABTS [2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation] assays and spectrophotometric measurements of color were compared.

RESULTS

The wines elaborated with chitosan and inactive dry yeast presented greater capacity to inhibit the formation of the 1-hydroxyethyl radical compared to the wines elaborated with stem or shoot extracts. The total content of anthocyanins was higher in the wines elaborated with SO₂ ; however, the concentration of flavan-3-ols was higher in the wines with chitosan. In addition, the wines with chitosan and inactive dry yeast presented the highest % polymerization. Wines elaborated with stem extract had a lower concentration of flavonols and stilbenes.

CONCLUSION

Chitosan and inactive dry yeast, which are used as an alternative to SO₂ in winemaking, allow the control of the formation of 1-HER in red wines. Wines with stem and shoot extracts showed a lower resistance to oxidation. © 2020 Society of Chemical Industry.

Bacteriophages as an Up-and-Coming Alternative to the Use of Sulfur Dioxide in Winemaking

Certain acetic and lactic acid bacteria are major causes of quality defects in musts and wines, giving rise to defects such as a "vinegary," "sharp, like nail polish-remover" taste or preventing alcoholic and/or malolactic fermentation. Sulfur dioxide is the major tool currently used in the control of these bacteria in wine. The aim of this work was to isolate bacteriophages from musts and wine of different grape varieties that were able to eliminate lactic and acetic acid bacteria spoilages at the laboratory scale. Musts obtained from grape-berries of Vitis vinifera cv. Chardonnay and Moscatel and a red wine made with V. vinifera cv. Tintilla de Rota were used to isolate bacteriophages. Bacteriophages were obtained from each of the musts and the wine and belonged to the order Caudovirals and the family Tectivirals. They were isolated by classical virology methods and identified by electron microscopy. The host bacteria used in the study were lactic acid bacteria of the species Lactobacillus hilgardii, Lactobacillus plantarum, and Oenococcus oeni and the acetic bacteria Acetobacter aceti. A comparative study was performed by adding phage titrations and SO2 to musts and wines, which had been previously inoculated with bacteria, to study the effectiveness of bacteriophages against bacteria. The comparative study showed that some bacteriophages were as effective as sulfur dioxide at low concentrations.

Natural antioxidants of plant origin

Interest in the content of natural antioxidants in plant-based foods can be from the human health perspective, in terms of how these compounds might help promote one's health and wellness, or from the storage point-of-view, as the endogenous antioxidant constituents aid to extend a foodstuff's shelf-life. This chapter reports essential information about the mechanism of antioxidant action and methods employed for determination of their activity, classes of phenolic compounds (phenolic acids, flavonoids, lignans, stilbenes, tannins), sources of plant antioxidants (oil seeds, cereals, legumes, plants of the Lamiaceae family, tea and coffee, tree nuts, fruits, and berries), extraction strategies of phenolic compounds from plant material, and the influence of processing and storage on the content of natural antioxidants in foods and their antioxidant activity. Thermal processing, if not releasing bound phenolics from the structural matrices of the food, tends to decrease the antioxidant potential or, in the best case scenario, has no significant negative impact. Gentler sterilization processes such as high-pressure processing tend to better retain the antioxidant potential of a foodstuff than thermal treatments such as steaming, boiling, or frying. The impact of processing can be assessed by determining the antioxidant potential of foodstuffs either at the point of formulation or after different periods of storage under specified conditions.