## 2 Avocado Processing and By-Products
This has the advantage that oil maintains the organoleptic characteristics of the fruit pulp. For this process, the cultivar 'Hass' was chosen as the raw material, due to its characteristics; particularly, its thick skin, which protects the fruit during transport, and its superior oil yield (around 31%) with respect to the rest of the cultivars or varieties. \"Hass\" is also the main cultivar commercialized worldwide [22; 23]. If this CPAO is extracted from high-quality fruits, the avocado oil is defined as extra virgin avocado oil [21]; this is similar to the nomenclature that the olive oil industry follows--according to its quality. Another similarity between CPAO and olive oil is that both oils are rich in the monounsaturated fatty acid oleic acid [20]. However, the yield is lower than using the aforementioned methods, up to 85% [20]. Currently, the use of this method has become more popular and it is also used in Chile, South Africa, Kenya, Israel, Samoa, and other countries [20; 21]. In general, this process begins with washing, draining, and destoning of the avocado, where the stones and around 90% of skin are separated from the pulp. Skin separation can be calibrated according to the desired quality, since the proportion of skin into the processed mash may affect the pigment composition of the avocado oil. The flesh goes through a grinder where it is simultaneously sliced and crushed, i.e., broken down. Subsequently, the avocado paste is continuously stirred, and the oil separated by centrifugation using a horizontal three-phase decanter. It spins the malaxed paste, separating the pomace (exhausted pulp and residual skin; fibrous material), a liquid phase (wastewater), and the oil (CPAO). In some cases where a vertical two-phase decanter is used, the liquid phase can be further processed in a centrifuge to remove the remaining CPAO from the wastewater [21]. The estimated amounts of waste per avocado fruit processed can be around 15% pomace, 45% wastewater, 27% skin + stones, and 5% residual water, while the CPAO is around 8% (or 8.5 L), depending on the avocado type [20]. Another star product of the avocado is guacamole, whose production process (Figure 5) consists of the selection of ripe avocados, washing, and, as for the extraction of oil, removing the peel and stone to recover the pulp. Then, it is mixed with others elements (onion, tomato, and salt, basically) to finally obtain the guacamole, which is packaged [24]. Figure 5: The guacamole process and by-products/waste generated (yellow squares). Regardless of the type of production method, the stone, peel, and/or exhausted pulp are discarded as waste, which results in a large amount of solid residues that can represent 21-76% of the fruit weight, with some exceptions in some varieties [25; 26], and also the wastewater. In the CPAO method, at most 10% of the skin can be included in the process [21], but the proportion of biomass material that is discarded remains very high, as commented on before. Therefore, the valorization of avocado waste deserves further attention on the basis of its chemical composition, including the major constituents and also the minor ones (but relevant).