ABSTRACT
Several by-products are generated by de-stemming, pressing, and decantation steps during the wine making process. ese materials are very rich in biodegradable organic matter and can support microbial growth and emission of environmentally undesirable odors and compounds. e wine residues, if not treated eciently, have the potential to initiate environmental hazards ranging from surface and groundwater pollution to foul odors. Indeed, a signicant negative environmental impact is seen due to discharge of wine waste (News 2014) and signicant nes have been issued for dumping of wine residues (Devesa-Rey et al. 2011; EPA 2014). Inappropriate disposal of grape pomace attracts ies and pests and this can create unwanted hazards (Bustamante et al. 2007). In some cases, where the wine solid residues are used as fertilizers or composts at excessive rates, plant growth is aected due to nitrogen immobilization or an increase of nitrogen leaching in soils treated with wine solids (Flavel et al. 2005; Bustamante et al. 2007). Supplementation of the wine by-product composts with minerals and micronutrients such as phosphorous can lead to problems pertaining to their heavy metal content (Del Castilho et al. 1993; Karaka 2004). Pinamonti et al. (1997) argued that the heavy metal content is a critical factor leading to restricted agriculture use of wine waste compost. Furthermore, tannins and other compounds from pomace can cause oxygen depletion in the soil and inltrate surface, soil and groundwaters (Arvanitoyannis et al. 2006). e problems mentioned indicate that current wine waste management practices can potentially lead to serious environmental pollution. It is becoming more
4.8.5 Grape-Seed Oil 171 4.8.6 Non-Food Applications 173
4.9 Fermentation174 4.10Green Material175
4.10.1 Grape Stalks175 4.10.2 Grape Leaves 176
4.11 Challenges and Opportunities 177 Acknowledgments 177 References 178
important and a subject of increasing concern for wine processors and scientists to nd a safe and economical use for grape and wine waste. Furthermore, utilization of wine by-products and the production of environmentally sustainable wine can have marketing advantage. Research from New Zealand indicated that consumers support the purchase of wine produced by green production practices and are prepared to pay a higher price for sustainably produced wine (Forbes et al. 2009). By-products generated from wine making can be broadly classied as follows: solid by-products (stalks and grape pomace), highly viscous by-products (wine lees), and low-viscosity by-products (wastewater) (Figure 4.1). e physical nature of the materials can to a large extent aect their economic potential for utilization, inuencing the composition and level of compounds of interest as well as the costs associated with bioconversion and maintaining the stability of the by-product (i.e., handling of solids or liquids will need dierent engineering requirements and storage of the material will depend on their stability against microbial and oxidative processes). Grape pomace (GP) is equivalent to about 20%
of the grapes used in wine making and is responsible for the largest amount of by-product generated from wine making with an estimated 10,930,834 Mt (Van Dyk et al. 2013). Grape pomace contributes to approximately 62% of the organic waste (Naziri et al. 2014) and therefore practical utilization is an urgent issue from an environmental perspective. GP may contain grape skin and pulp (10%–12% of grapes), seeds (3%–6%), and stalks (2.5%–7.5%) (Wadhwa et al. 2013) (Figure 4.2). e composition depends largely on the wine production system (white wine versus red wine), the grape variety and maturity, production size, the use of machinery for the separation of grapes before crushing, separation techniques used, and type of wine variety that is being produced. Several compounds can be recovered from GP such as oil (12%–17% of the grape seeds weight), protein, carbohydrates (up to 15% sugars and 30%–40% ber), phenolics/ pigments (0.9%), and tartrate (0.05%–0.08%), which are suitable for a range of useful products that can be used in food, pharmaceutical, and agricultural industries. Given the massive amounts produced and its organic load, the utilization of GP is seen as an important activity to eliminate the environmental problems associated with
the disposal of GP as well as an opportunity to add value and generate extra income from the by-product. Lees and stalks represent signicant sources of organic waste, 14% and 12% of organic byproduct generated during wine making, respectively (Naziri et al. 2014). Grape seeds can be separated from GP and used for the production of linolenic-rich oil (12%–20%), carbohydrates (60%– 70%), protein (about 11%), and phenolics (5%–8%) (Naziri et al. 2014) (Figure 4.3). ese valuable compounds have several useful applications as animal feed, and food, cosmetic, and pharmaceutical ingredients. e conventional uses of solid wine by-products are animal feed (Louli et al. 2004) and fertilizer/compost (Kammerer et al. 2005) without or with little further processing. However, in recent years, there has been a growing interest in the exploitation of wine industry waste in other applications as the awareness of the potential commercial value has become known. For example, it was found that during the wine making process, while soluble phenolic compounds that are present in the vacuoles of the plant cells are extracted, a large amount of phenolic compounds bound to the
cell walls are not (Meyer et al. 1998). Compounds extracted from wine by-products with high phenolic content may be able to exert positive eects on human health, to protect against cardiovascular disease, to produce anti-inammatory activity and anticarcinogenic eects as well as being used as food antioxidants (Shrikhande 2000; van de Wiel et al. 2001; Khanna et al. 2002). Many researchers have reported that the extracted natural antioxidants and various phenolic compounds from wine by-products, including grape seeds, skin, exhausted pomace, grape stalks, wine lees, and grape pomace, are safer to use than synthetic antioxidants (Alonso et al. 2002; Negro et al. 2003; Arvanitoyannis et al. 2006). e recovery and utilization of winery by-products could not only reduce the waste disposal burden and other environmental issues, but could also lead to the development of new healthier, robust ingredients, and extract compounds for both the pharmaceutical and food industries. Due to the aforementioned benecial properties, wine by-products are now available as dietary supplements. Products such as GSE, grape extract, and red wine powder are sold commercially. Table 4.1 summarizes the physicochemical properties and potential use of wine by-products. Recently, viable new business opportunities have emerged from within the wine industry. ere is an increasing interest from several industries, including the food industry, to utilize antioxidants and other phenolics from wine by-products and this has resulted in several applications being developed. One of these is the extraction of anthocyanins, known as “enocyanin,” to be utilized as food colorants (Alonso et al. 2002). Patents have been awarded to researchers related to their work in processing and developing commercial products in cosmetic and pharmaceutical industries from grape seeds, skin, and related avonoids (Carson et al. 2001; Henry et al. 2001; Pykett et al. 2001; Ray and Bagchi 2001). Other than human-orientated applications, wine waste can also potentially be utilized for alternative applications such as absorption of heavy metals (namely lead and cadmium) (Farinella et al. 2007); and for the production of pullulan, a polysaccharide that has many food and pharmaceutical applications (LeDuy and Boa 1983). An interesting and newly reported approach toward the integrated utilization of grape skins consists of consecutive or simultaneous extraction with a neutral organic solvent and water under reux (Mendes et al. 2013).
