The production of wine is among the leading agricultural practices across the globe. Making wine requires using many precious resources, including fertilizers, water, and other organic substances. Additionally, it generates lots of waste and organic waste that needs to be treated appropriately to avoid contamination of the production areas. The kind of generated waste is based upon the vinification processes that also impact the physical and chemical properties of the remaining material, determining its future use and the specific recovery circuit that could be integrated.
1. Introduction
One of the biggest environmental issues in the countries that produce is the growing quantity of lignocellulosic materials produced through the expansion of agroindustrial activities over the past 100 years. To help create a healthier environment, waste products generated by chemical, mechanical, and biological methods are utilized as raw materials for developing new applications and products. It is a so-called circular economy that aims to create a “zero waste” society [ 1 ].The vineyard industry has been among the strongest in various regions around the globe. The vast amount of land dedicated to cultivating vineyards makes it one of the primary agricultural activities of humans. The huge amount of production comes with the use of a vast quantity of resources, including water consumption as well as the use of organic or inorganic materials (fertilizers). Sustainable wine production must be accompanied by properly utilizing these elements on the field and within the wine cellars. Vine cultivation in itself, and essentially the winemaking process in cellars, generates large quantities of waste and off-products, such as seeds, pomace, stems as well as prunings, yeast, and organic acids (tartrate), CO 22, and as well as water. Unfortunately, only a tiny amount of these materials can be used to fertilize livestock feed or create other goods. Additionally, the byproducts from wine could be utilized to evaluate active ingredients or bioactive phytochemicals, which can be used to produce food, pharmaceutical and cosmetic components 2, 3 ].The term “sustainable” is somewhat difficult due to the specific issues about the environment of various wine-producing regions. Sustainability is the process of reducing the amount of residues that are left behind and how they are used when making the wine. In the production chain, this requires proper control of resources in terms of energy and water efficiency for both wineries and vineyards. Sustainability is becoming more important for people’s minds as climate change becomes an ongoing issue within the twenty-first century. Traditional winemaking processes are conducted using methods that have been used for hundreds of years. practice. The materials utilized for the process, in terms of equipment and people, haven’t changed much over the years. Thus, using innovative technologies designed to minimize the amount of garbage created during the process is not an easy undertaking. Scientists must develop methods that allow the recycling and transformation of waste products with an element of innovation. However, markets require new products, and modern societies expect them to be manufactured sustainably. All of this has to be accomplished within an ever-changing legal environment. Procedures have to be effective and legal. 1 ].For instance, we could use FAO statistics showing that the most popular items in Spain include barley beer and wine, olive and soybean oil ( http://faostat.fao.org ). Producing these food items does not exclude the production of massive amounts of byproducts (millions of tons every year). If we do not wish for environmental damage to have permanent effects, we must implement a proper management plan to eliminate them or lead to others. In the case of byproducts produced in large quantities in wineries, we focus on grape stems and pomace (GPS).These products aren’t harmful in and of themselves, but their large organic matter content, in conjunction with the fact that they are made during the peak of the season and are a major environmental issue. 4 ]. GPS is a rich source of tannins; in another way, it is a high source of antioxidants and high levels of hemicellulose produced mainly by xyloglucans. The utilization of grape stems has been suggested as a biosorbent substance to remove harmful substances, for example, composting, and for producing high-value substances like antioxidant-active phenolic compounds. The phenolic compounds have antioxidant activity. 5 ]. Wineries are among the main agro-industrial industries within Southern Europe countries [ 6 ]. It is recognized these industries produce huge quantities of residues and also result in a huge loss of useful substances. A few efforts have been made to reuse byproducts in different production chains. From an economic and environmental standpoint, the most important problems of management can be addressed. In the first instance, it is an important problem to determine how to quantify and identify the garbage. In the second stage, the sources of residue and ingredients with high value-added are evaluated. Both conventional and innovative techniques for processing must be considered.However, it’s difficult to cut down on the production of waste within wine production processes since some techniques are based on traditional processes and are governed by the physical infrastructure or human resources 7 ]. In the end, it is essential to create valorization processes that will lead to the introduction of waste management within the sector of wines. Because markets increasingly demand new products at the end of the line, along with the environmental impacts of the environmental hazards related to the process, lawmakers have been guided to develop a legal framework. On the one hand, it must facilitate improvements in recycling byproducts and the reuse of waste and, on the other hand, to ensure the effectiveness of production processes.Wine production is among the main agricultural practices across the globe. Europe (Italy et al.), America (USA, Argentina, Chile), Australia, South Africa, and China are the most important production areas. The main production areas are China, South Africa, and Australia. 8 ] ( Table 1 ). Table 1. Production of wine worldwide (millions in hl).A total of 300 million hl was produced in the 2018 campaign, According to the International Organisation of Vine and Wine ( http://www.oiv.int ). It is widely known that wine production requires using many sources, including organic additives, water, or fertilizers. Additionally, the process produces large quantities of organic waste (skins or branches and seeds) as well as wastewater. Based on the various procedures employed to make wine in different production areas, the amount of waste generated varies little. These factors affect the physical and chemical properties of discarded material, and the characteristics determine its future use and the particular recovery circuits in which it can be used to reduce the environmental footprint. Being a responsible wine producer integrated into a sustainable economy requires innovative approaches that suggest and analyze possible solutions from a technology standpoint. 9 ].
- Characterization of Different Winery Residual Biomasses
2.1. Winery Industry
Winemaking generates different residues Figure 1 Characterized by high levels of biodegradable components and suspended solids 10, 11 ]. While winemaking is considered a green process, in manufacturing, between 1.3 to 1.5 kilograms of trash are produced per liter of wine 75% is water. 12 ]. The other central residues resulting from winemaking activities are represented by organic wastes (grape the pomace that contains skins, seeds, and pulp along with grape stems and leaves of grapes) and wine lees. Emissions of CO2, greenhouse gases (CO 22, volatile organic compounds, etc. ), and other inorganic materials (diatomaceous earth bentonite clay, perlite). In total, 14.5 million tonnes of byproducts from grapes are made annually in Europe all by itself 13 ].Figure 1. Illustration of the vinification process, including the produced residues.Bustamante and others. [ 14 ] examined various residues of the wine industry and discovered that the distillery and winery wastes have a moderate pH (mean values varied between 3.8 to 6.8) as well as electrical conductivity (1.62-6.15 Ds/m) and high organic matter content (669-920 kg/L). Additionally, winery wastes contain large amounts of macronutrients, particularly K (11.9-72.8 grams per kilogram), large amounts of polyphenols (1.2-19.0 kg/L), and low levels of heavy metals and micronutrient content. The waste has to be cleaned before use since these characteristics are incompatible with agriculture requirements. The requirements for agricultural use are not compatible. 14 ].
2.2. Grape Leaves
Vitis vinifera (L) leaves are the vineyard and winery industry’s least studied or valued residues. The limited information regarding its composition suggests the number of organic acids and flavonols, phenolic acids, vitamins, enzymes, carotenoids, tannins, anthocyanins, and procyanidins. Terpenes, terpenes, and reduction or non-reducing sugars, are fascinating. 15 ]. The chemical compositions of the vine leaf have attracted interest in this particular plant as a novel source of goods with intriguing nutritional properties, increasing the biological value of this plant. The vine leaves are currently used in manufacturing food ingredients, and their juice is used to wash the eyes due to its antiseptic effect. 16 ].
2.3. Grape Stems
Grape stems, or grape clusters, are different waste products the winemaking process produces. Procyanidins in them are a great source of astringent chemicals that could be used in various other processes. 17 ]. To prevent a negative impact on wine’s organoleptic qualities, this component is eliminated prior to winemaking. The stems are between 1.4 percent and 7.0 percent of the total material processed 18 ]. It is said that the value for commercial use of grape stalks is minimal. Their most common uses are producing nutritious compounds to feed the soil and fattening animals. Specific authors argue that their chemical compositions are sufficient to be considered an antioxidant source or dietary fiber 19 ]. The moisture content of the stems of grapes is reported to range between 55% and 80 percent, with the more pronounced variation being due to the variety of grapes. The percentage of grape stems with alcoholic non-soluble residues amounts to 71% of dry matter, and no distinctions between red and white varieties have been noted. 20 ]. Concerning the composition of phenols, their presence has been demonstrated in flavan-3-ols, hydroxycinnamic acid monomeric flavonols, oligomeric and monomeric stilbenes, and flavonols 21 ]. In this context, the phenolics extracted from grape stems are about 5.8 percent on a dry weight basis 22 ].
2.4. Grape Pomace or Press Residues
Making grape juice is accompanied by creating other waste, usually called grape pomace. The variation in the amount of grape pomace compared to the number of grapes used in the process is determined by the amount of material considered and the possibility of incorporating stems of grapes in the waste while formulating the proportion. 23 ]. Regarding the overall content of the pomace, the moisture ranges from 50%-72% based upon the variety of grape chosen and the maturing rate. Insoluble residues have a percentage of between 16.8 percent and 24.2 percent, and the protein content is less than 4 percent. As is the norm, they are the main polymer component of the cell wall in the pomace of a grape and range between 37% and 54% of cells’ polysaccharides. In contrast, cellulose is the 2nd type of polysaccharide in the pomace of grapes and varies between 27 percent and 37% 20 ]. Let’s analyze the composition of grape pomace. It is distinguished by its ability for various industrial processes, including the extraction of grape seed oil as well as polyphenols (including flavonols, anthocyanins flavanols, and phenolic acids as well as Resveratrol) and in the manufacture of citric acid and methanol, the fermentation of ethanol and xanthan as well as in the generation of energy via mechanization. In light of its polyphenolic contents, several authors have concluded that this byproduct is infused with high antioxidant power and suggests that the grape pomace from wineries could be utilized in the cosmetic, pharmaceutical, and food sectors as a replacement source of antioxidants from nature. 2, 24 ]. Another alternative is to think about the grape pomace separately, with the seeds on one hand and the skins on the other. The proportion of seeds ranges between 38% and 52 percent of dry matter, according to specific sources 25. Some people believe that a lower percentage of it. It could be about 15% of the grape pomace 26 ]. Regarding the grape seeds’ composition (w/w), the fiber content can reach 40 percent, 16% of which is essential oils, 11 percent protein, and 7% complex phenolic compounds such as tannins and other compounds like minerals and sugars 27 ]. The content of phenols in grape seeds is also fascinating since it is between 60% and 70% of the total extracted compounds. This is highly appealing because only a tiny portion is extracted during pressuring grapes. 28 The fact has drawn the industry’s attention to use the plant as an ingredient for natural antioxidants 29 ]. Usually, the grape skin makes up 70% of the substance that makes up the pomace of a grape. The skin of the grape is significant in phenolic compounds. However, the yield of the end product is contingent on the vinification process and method of extraction used. [ 30 ]. So, the skin of a grape is significant in phenolic compounds even though the amount depends on the winemaking process and extraction process employed. Certain factors, such as the solvent type temperature, time, or type of solvent, can affect the process 31 ]. Moreover, the pomace of grapes has an exciting percentage of linoleic acid (55-75 percent) 55-75% 32 ]. Additional research is suggested since there is no information about the composition of fatty acids of the grape pomace. Grapes are believed to have significant amounts of polyphenols, with as high as 70% remaining in the pomace following the extraction of grape juice (see below). 33 ]. The principal polyphenols present in the pomace of grapes are phenolic acids, flavan-3 ols, and flavonols, as well as anthocyanins and proanthocyanidins. Different cultivars’ total phenolic and flavonoid content varies between 55.5 and 153.8 milligrams gallic acid equivalent (GAE)/g, respectively. 38.9 up to 91.7 mg rutin equivalent per gram, respectively. Monomeric anthocyanin, total tannin, and proanthocyanidin levels in the grape pomace extracts vary between 54 and 152.2 mg GAE/g 0.02 and 11.2 mg equivalent to cyanidin-3-glucoside per gram, between 21 and 51.7 percentage, respectively. 33 ].
2.5. Wine Lees
The wine lees are the relics that accumulate in the bottom of wine production tanks following fermentation and are removed when it is being stored or following further treatment. It also includes the waste produced after centrifuging and filtering the product. The most common composition of lees is tartaric acid, yeast, phenolic compounds, and various other substances of an inorganic nature 34 ]. Lees are crucial in winemaking, as they are in contact with (poly)phenolic compounds, which directly affect color and other organoleptic properties and absorption of them 35 ]. Furthermore, lees release enzymes that facilitate the conversion and hydrolysis of (poly)phenolic substrates in phenolics with significant added value and interest, such as gallic acid and ellagic acid [ 36 ]. Anthocyanins are present (6-11.7 mg/g x Dw (dry weight)) as well as various other compounds known as phenols (29.8 mg/g x Dw) in wine lees 34. The same has been mentioned. It is exciting to look at the lees of wine. Their high concentration of bioactive molecules can be extracted to create extracts or semi-finished products suitable for use in the nutraceutical, food, and pharmaceutical industries. This means they are being examined from various viewpoints.
