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Avocado oil manufacturing app
Avocado oil manufacturing app guides users thru the avocado oil production process, for maximum avocado oil yield and quality.

Avocado oil manufacturing app

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Avocado oil manufacturing

Let the Producepak app guide you thru the avocado oil manufacturing process. Make sure the correct tasks are done at the correct time for maximum avocado oil yield and quality.

What is unrefined, extra virgin cold-pressed avocado oil?

The high oil content of the avocado fruit (Persea americana Mill.) has been known since Aztec times, with the fruit sometimes referred to as "vegetable butter" or "butter pear." The plant originated in Central America, and its cultivation has spread to warm subtropical and temperate climates worldwide. The flesh of an avocado can contain up to 30% oil (based on fresh weight), but there is very little in the seed (≈2%) or the skin (≈7%). Avocado oil was originally, and still is, extracted for cosmetic use because of its very high skin penetration and rapid absorption. Following pre-drying of the avocado flesh to remove as much water as possible (≈65% water in avocado flesh), avocado oil for cosmetics is traditionally extracted with solvents at elevated temperatures. After extraction, the oil for application in skin care products is usually refined, bleached, and deodorized, resulting in an odorless yellow oil.

Avocados are primarily grown for the fresh fruit market, either domestic or export. There are 12 major cultivars of avocado, but the main cultivars grown globally are ‘Hass' and ‘Fuerte.' The ‘Hass' cultivar constitutes more than 90% of the avocado crop in New Zealand (NZ) as this cultivar has excellent yield potential and also suffers less postharvest and handling disorders owing to their thicker skins. In 2000, two processing companies in NZ began production of extra virgin avocado oil; they pioneered the process for extracting cold-pressed avocado oil, which is sold as culinary oil for use on salads and for cooking (Eyres et al., 2001). Like extra virgin olive oil, cold-pressed avocado oil is unrefined and so retains the flavor and color characteristics of the fruit flesh.

Production levels in NZ vary year to year depending on the season (some trees bear fruit biennially), weather (wind and storms can damage fruit, which are then not suitable for fresh fruit export), and export markets. Over the 2008/2009 season, NZ processors produced more than 150,000 liters of extra virgin avocado oil, with production expected to increase in the 2009/2010 season. Extra virgin avocado oil is also being produced in Chile, South Africa, and Kenya. Extra virgin avocado oil from NZ is exported to Australia, Japan, Southeast Asia, Europe, and North America by Grove Avocado Oil (Tauranga, NZ) and Olivado (Kerikeri, NZ). Avocados are primarily grown in NZ for fresh fruit export; any fruit not suitable for export is sold on the local market or to processors (for oil and other processed avocado products). Approximately 3% of the NZ avocado crop is processed for the oil. Windfall fruit not suitable for the local market is sometimes bought by oil processors. Fruits that are rotten or exhibit postharvest disorders and are unsuitable for consumption are not used for oil production.

The process developed in NZ for extraction of avocado oil is based on the mechanical extraction method used for olive oil. However, before we discuss the extraction process, we need first to consider the avocado fruit and its development. It is important to understand the pre- and postharvest physiology of avocados, particularly how their maturity and degree of ripeness impact the optimum time for oil extraction.

Avocado oil is traditionally made from poorer quality fruit, and often only used in cosmetics. However, Alfa Laval has developed a completely new way to produce cold-pressed avocado oil that can be used in higher-margin food products. All you need is a special washing, de-stoning and de-skinning section for avocados. You can deal with all the other extraction stages using standard high-technology Alfa Laval olive oil processing equipment.


EXTRACTION OF AVOCADO OIL

The process for recovering oil from ripe avocados is a mechanical extraction, similar to olive oil extraction, with the additional step of removing the skin and stone (seed). After this, the flesh is ground to a paste and then malaxed for 40-60 minutes at 45-50°C. This is a higher malaxing temperature than used for olive oil extraction, but it is still considered to be cold-pressed extraction for avocado oil. The slightly higher temperature aids the extraction of the oil from the oil-containing cells and does not affect the quality of the oil. The oil and water phases are separated from the pulp using a high-speed decanting centrifuge, and then the oil is separated from the water in final polishing centrifuges. The pulp from the decanting centrifuge and waste skin/seeds are returned to orchards for soil conditioning and mulch, or used as animal feed.

Avocado oil, if extracted from sound fruit (no rots, physiological disorders, or damage), will result in oil with a very low percentage of free fatty acids (%FFA) (<0.5% as oleic acid). Also, the peroxide values (PV) can be very low (<2 meq/kg). Recommended standards for extra virgin avocado oil have proposed a maximum PV of 4 meq/kg (Table 1).

In sound, ripened fruit, the level of lipolysis that occurs is low, resulting in low %FFA. The fruit does not need to be processed immediately after ripening, but long delays should be avoided. Generally a higher %FFA is due to poor-quality fruit, delays in processing ripened fruit, or poor manufacturing practices.

Avocado oil manufacturing app
Avocado oil manufacturing app

PROPERTIES OF AVOCADO OIL

Extra virgin avocado oil from the ‘Hass' cultivar has a characteristic flavor, is high in monounsaturated fatty acids, and has a high smoke point (≥250°C), making it a good oil for frying. ‘Hass' cold-pressed avocado oil is a brilliant emerald green when extracted; the color is attributed to high levels of chlorophylls and carotenoids extracted into the oil.

Cold-pressed ‘Hass' avocado oil has been described as having an avocado flavor, with grassy and butter/mushroom-like flavors. Other varieties may produce oils of slightly different flavor profile as has been seen with ‘Fuerte,' which has been described as having more mushroom and less avocado flavor.

The fatty acid profile is very similar to olive oil, in that it is very high in oleic acid. A typical avocado oil has 76% monounsaturates (oleic and palmitoleic acids), 12% polyunsaturates (linoleic and linolenic acids), and 12% saturates (palmitic and stearic acids); these values are given as percentage of fatty acid/total fatty acids. The main antioxidant in the oil is a-tocopherol, which is present at levels of 70-190 mg/kg oil. b-, g-, and d-tocopherols are only present in minor amounts (<10 mg/kg oil). Other nonlipid components present in the oil include chlorophylls (11-19 mg/kg oil) and carotenoids (1.0-3.5 mg/kg oil).

The chlorophylls from the flesh and the skin contribute to the characteristic emerald green color of the oil. Depending on the location in the mesocarp, the chlorophyll content varies, but the majority of chlorophyll and carotenoids are present in the greener layers of flesh next to the skin. If avocado skin is included in the pulp during malaxing, then the likelihood of extracting more pigments is greater. Chlorophyll does not contribute to oil stability but can be a problem, as chlorophyll can act as a sensitizer for photo-oxidation to occur. Therefore, it is important to store the oil away from light.

Carotenoids in avocado fruit have long attracted attention for their potential anti-carcinogenic effect; these same carotenoids are subsequently extracted into the oil. The most significant carotenoid present in the oil is lutein (0.5-3.3 mg/kg oil). Lutein is beneficial for eye health by reducing the progression of age-related macular degeneration. The cold-pressed avocado oil also contains high levels of phytosterols (b-sitosterol being the main sterol present), at 2.23-4.48 mg/g oil. Based on its fatty acid makeup and the presence of these phytochemicals, extra virgin cold-pressed avocado oil is considered to be a healthful oil.

STANDARDS FOR AVOCADO OIL

The impacts of postharvest procedures, preprocessing treatments, extraction, and storage on the composition, quality, and sensory characteristics of avocado oil have been investigated over the last 10 years in NZ in collaboration with Australian and Californian research groups. Standards have been proposed for avocado oil, including extra virgin, virgin, and pure grades of oil (Table 1). These standards have been recommended to ensure that avocado oil sold is of good quality in terms of standard quality indices, composition, and sensory properties. The standards are unique to avocado oil, where cold-pressed avocado oil is recovered by mechanical extraction at temperatures less than 50°C, without solvents; water and enzymes can be used. These standards are important, as the production and culinary consumption of cold-pressed avocado oil, with its light, distinctive flavor, is increasing worldwide.

proposed standereds for avocado oilAvocado oil manufacturing app
Avocado oil manufacturing app

Processed avocado products:

Avocado is also used for the confection of baked products (such as cakes), to elaborate fine soup mixes, appetizers, and in the production of cosmetics (oils, skin lotions, soaps, shampoos, etc.) due to its oil content. Avocado oil is appreciated because it contains biodegradable and easy to absorb sterol. The oil is sent to theUnited States, where it is refined and then sent toJapanandEuropeas edible oil and cosmetic ingredient. Besides being an important cosmetic ingredient, the pharmaceutical industry considers the unsaponifiable fraction of the oil as a valuable raw material. From this fraction, the factor H is extracted, which is used in the pet food and cooking oil industries (SAGAR, 1999).

Types of products:

Frozen avocado – Original Chunky Avocado Pulp in 1, 2,& 6 lb. plastic pouches.

Avocado sauce- 100% Hass Avocado with minced onions and spices.

Southwestern guacamole – Feisty blend of chunky avocado, red bell pepper, onion, jalapeños and spices

Non-refined avocado oil – oil is extracted from selected Hass avocados by mechanical processes

Processing techniques

Avocado can be processed into avocado salsa, guacamole blend, avocado pulp, spicy guacamole, and avocado drinks.

Upon receiving the fruit, it is washed in a machine with rotating brushes and chlorinated water (200 ppm). Then its temperature is homogenized to 5°C to allow an even ripening. Avocados are stored for 3 days at 20°C at a relative humidity over 85%, adding 10 ppm of ethylene. Afterwards, the temperature is lowered again to 5°C and the fruit is kept at that point until processing (3 to 4 days). Since many clients prefer a chunky texture, the fruit must be ripe and firm.

Processing begins with a selection step, where the unsuitable fruit is discarded, the peduncle is removed, and the fruit is submerged in chlorinated water (200 ppm) for 10 min. Then it is cut, de-seeded, peeled and put into a mixer with other ingredients, such as onion, chili pepper, fruit concentrate, erythorbic acid (to promote color retention), and ascorbic acid. The resulting product is vacuum-packed and sealed into co-extruded five-layer bags, with a high barrier to oxygen. They usually pack in 6 pound bags, because most of their customers are restaurants, but they also have a 250 g package for retail marketing. The bags are frozen in a blast-freezer at -30<°C, and afterwards the bags are stored at -18°C).

Avocado fruit and oil extraction

The avocado plants include three different horticultural varieties named after their presumed areas of origin: Guatemala, Mexico and West Indies. Each variety is marked by many different traits, some of which are of commercial relevance (Bergh and Ellstrand, 1986). Today, from the agronomical point of view, there are many varieties with a wide range of sizes, forms and compositions of the fruit. For instance, For instance, Table 1 reports the characteristics of different fruits from varieties harvested in Venezuela (Gómez López, 2002) and clearly shows an example of their variability in particular in terms of size, oil content and seed/pulp proportions. In general, the fruit is roughly pear-shaped and more or less elongated. Its weight may range from 60 g to 700 g. The relative amount of pulp varies from 60 to 75% according to the cultivar. The oil content may also vary widely. The kernel contains only about 1% of oil, whereas the skin accounts for less than 4% (Jacobsberg, 1988). Figure 1 shows the average composition of a Hass avocado from New Zealand. Requejo-Tapia (1999) in New Zealand described the Hass variety as being the most compatible with high-quality oil extraction due to its large amount of flesh with a high oil content. Depending on the location of the orchard, the oil content of these fruit flesh can range from 16-17% in September to 25-30% in April depending on the fruit ripening stage (Requejo-Tapia, 1999).

The market of fresh avocado is certainly the main one and also generates a remarkable quantity of second-grade produce which is discarded, despite its relatively high oil content. The avocado oil can be extracted in different ways. It is contained in a finely-dispersed emulsion in the cells of the fruit pulp. Hence, the extraction process requires rupturing not only the cell walls, but also the structure of the emulsion (Lewis et al., 1978). Traditionally, this oil used to be obtained by mashing the pulp in water, then heating and skimming off the supernatant oil. Later, for cost reasons, most producers started to extract oil from dried fruits by means of solvents (Sadir, 1972; Human, 1987; Martinez Nieto et al., 1988). Two main methods are in use to extract avocado oil for industrial production. According to the first method, fruits are dried and pressed at high temperature, subsequently oil is extracted by means of organic solvents. In the second method, oil is separated from fruits by centrifugal or pressing forces, then oil cells are submitted to mechanical and enzymatic distruction (Human, 1987; Werman and Neeman, 1987; Martinez Nieto et al., 1988; Bizmana et al., 1993). The second method was developed in order to cut energy costs and minimise the air pollution caused by organic solvents. Nevertheless, in both cases, the crude avocado oil still needs to be refined before final consumption and use in the cosmetic industry, where it is particularly appreciated for its high vitamin E content and emollient properties, although it is considered marginal as a food product (Eyres et al., 2001). The first attempt to develop a method to produce cold-pressed oil intended to obtain high-quality edible oil was made back in the late 1990’s by a New Zealand company in collaboration with Alfa Laval (Eyres et al., 2001). In the follow paragraph we compare shortly the three main extraction methods: chemical extraction by solvent, traditional mechanical extraction and the most recent cold-pressed mechanial method for high-quality edible oil. In the description of the last one, we will focus in particular on Alfa Laval extraction plant, process parameters and oil quality. However this paper does not mention other variations of the main methods used in the past for avocado oil extraction (Human, 1987).

Chemical extraction by solvents

Organic solvent extraction is the most widespread. Warm air drying of the pulp followed by hexane solvent extraction yields 95% oil (oil extracted/oil content). The resulting oil is brownish with a high pigment content and needs to be refined for most applications. Refining consists of three steps: deacidification to remove free fatty acids which are less than 1% in good-quality fruits; bleaching to remove chlorophylls and their degradation products, pheophytins, as well as carotenoids; de-odourisation. When oil is sold crude, it is generally winterised at 5°C and drummed in lacquer-lined drums (Human, 1987; Martinez Nieto et al., 1988).

Traditional mechanical extraction

The mechanical method has been used traditionally in locations where drying facilities and/or solvent extraction units cannot be insalled. However these processes have poor yields and frequently require the use of chemical aids.

Avocado oil extraction was generally obtained by peeling and destoning the fruit, mashing the pulp and eventually drying it, then heating the paste with hot water with chalk and/or NaCl, and spinning, pressing or skimming off (by natural decantation) the oil (Figure 2) (Werman and Neeman, 1987; Bizmana et al., 1993).

The centrifugation/pressing yield is 60-80% (oil extracted/oil content) depending on the fruit variety.

An extensive literature describes the mechanical method and compares different process conditions in relation to yield and oil quality. After peeling and de-stoning, the pulp is mashed with hot water. Werman and Neeman (1987) recommend a dilution ratio of 1/3 and a 30-min treatment at 75°C. Bizmana et al. (1993) found the best combination with a dilution ratio of 1/5 and a 5-min treatment at 98°C. Traditionally, the mechanical method gives low yields, which can however be increased by maintaining the pH between 4.0 and 5.5 by adding chalk (CaCO3, CaSO4) or salt (NaCl) to the paste before centrifugation. The presence of monovalent and divalent cations activates enzymes with pectinase activity, therefore at certain concentrations the cellulolytic and proteolytic activities are unaffected. The addition of salts favours the extraction from difficult pastes (Dominguez et al., 1994). Bizimana et al. (1993) reported good results with an addition of 5% (w/w) CaCO3 or CaSO4. NaCl improves oil extraction only at a low concentration (<15%), but it causes a significant corrosion of the equipment (Werman and Neeman, 1987). Also when the traditional mechanical method is used, the resulting oil normally needs to be refined depending on the desired use. The refining system is the same described in the previous paragraph.

In a complete review about avocado oil (Jacobsberg, 1988), the author maintains that the mechanical extraction method compared with the chemical method and without chemical aids offers the best-quality oil, but it has an poor cost/benefit ratio. More recently has been demonstrated that oil extracted from pressed and microwave-dried avocado pulp presented the lowest acid and peroxide values and the highest oxidative stability in contrast with the oil from ethanol extraction. Combining microwave drying and pressing of avocado pulp seems to be able to led to a superior quality avocado oil (Santana et al., 2015).

Cold-pressed extraction: complete process plant from Alfa Laval

In the late 1990’s, a processing company in New Zealand began production of cold-pressed avocado oil (CPAO) to be sold as culinary oil for salads and cooking (Eyres et al., 2001). This project was developed in collaboration with Alfa Laval, a leading food processor, which leveraged its significant experience and technological expertise in cold-pressing extra-virgin olive oil (EVOO) to develop a novel extraction method to obtain high-quality avocado edible oil. Like EVOO, CPAO is not refined and maintains the chemical, organoleptic and flavour profile of the fruit flesh. In the 2008/2009 season, the New Zealand processors produced more than 150,000 liters of CPAO with approximately 3% of the avocado crop grown for oil production (Wong et al., 2010). Today CPAO is produced also in Chile, South Africa, Kenya, Israel, Samoa and other countries. Subsequently they built a complete processing plant to extract CPAO from the avocado fruit. The extraction process in use is showed in the flow chart described in Figure 3.

Fruit washing, destoning, deskinning and mash preparation

Whole fruits are washed in a two-stage washing system (Figure 4A). The first washing is performed by immersion in order to remove dust from the surface of the fruits. The soft water flow generated by a jet system gathers fruits by a plastic bucket elevator, which has two functions, i.e., washing fruits a second time by showering them and working as a water dripping. The elevator takes then the fruits into the destoning machine (Figure 4A), where pips and around 90% of skin are separated from the pulp. Skin separation needs to be calibrated according to the desidered quality, since the proportion of skin into the processed mash may affect the pigment composition of avocado oil (Ashton et al., 2006; Wong et al., 2011) like it does in olive oil (Criado et al., 2007). Pigments are important for the intensity of the green colour, its stability and its healthy effects (Woolf et al., 2009). The pulp (which is crushed during destoning) with a variable proportion of skin is pumped into a disc crusher (Figure 4B) for further refining. The disc crusher (Alfa Laval exclusive design) rotates continuously at 1400 rpm. The avocado mash is conveyed at the center and then sprayed towards the periphery by a toothed disc after the de-stoning process The disc crusher is important to cut the filaments remained in the paste and, at the same time, to minimise the emulsion. This approach has enabled us to optimise oil extraction. The same kind of disc crusher is used to crush the whole olive fruit and prepare the olive paste before EVOO extraction (Uceda et al., 2006; Amirante et al., 2010a). In addition the disc crusher has the important effect of chopping cutting very finely the skin for maximum pigment extraction. This disc crusher design is specifically used to extract olive oil with the maximum amount of chloropyll and carotenoid pigments (Costagli, 2006).

Thermal conditioning and kneading/malaxing

After crushing, the avocado mash is pumped into the section equipped with malaxers (kneading machines). Each kneading machine (Figure 4D) consists of a stainless steel tank with a central screw stirring the mash slowly and continously at a monitored temperature. The effect of the kneading machine on the avocado paste is very similar to the one already described for the olive paste: small oil drops released during fruit milling merge into large drops (coalescence phenomena) that can be easily separated by centrifugal extraction (Martinez Moreno et al., 1957). The optimal malaxing time and temperature to reach the best compromise between quality and quantity of extracted olive oil has been investigate in depth. On average we should consider as optimal a malaxer temperature lower than 30°C and a malaxing time between 30 and 45 min (Angerosa et al., 2001). Likewise, since the avocado oil comes in a finely dispersed emulsion inside the cells of the fruit pulp, the extraction process requires rupturing not only the cell walls, but also the structure of the emulsion (Lewis et al., 1978). In the case of the avocado mash, our experience showed that malaxing time should not exceed 90 min and temperature should be below 50°C. In particular the malaxing time is longer and the temperature is higher for avocados than olives due to the finely dispersed emulsion contained in the pulp cells. These emulsions are surrounded by the lipoproteic membranes or the lipophilic solids of the paste, which can absorb part of the oil itself. An oil-free paste and a good yield can be obtained by exploiting the mechanical and natural enzymatic action of malaxation (Dominguez et al., 1994). In olive oil it is amply demonstrated that a positive effect on the yield can derive from the use of physically draining products, such as talcum (Alba Mendoza et al., 1982) or other enzymatic products (Di Giovacchino, 1991). This positive effect on the yield can certainly be obtained also in avocados without affecting the final oil quality. A laboratory test on avocado oil during mechanical extraction showed a positive effect of a treatment with α-amilase enzymes or a mixture of α-amilase and protease (Buenrostro and Lopez-Munguia, 1986). Coalescence and oil extraction are not the only purpose of the crushing and malaxing procesesses. In EVOO extraction, the total phenol content and aromatic fraction are strongly affected by the extraction technology. In particular total phenols in EVOO drop when malaxing time and temperature increase (Di Giovacchino, 1991; Di Giovacchino et al., 2002). Furthermore, aromatic compounds in EVOO are rapidly generated during olive crushing (Angerosa et al., 1998). During this process, the evolution of the aromatic fraction is strongly influenced by malaxing time and temperature and shows different correlations depending on the different kinds of compounds (Morales et al.,1999; Salas and Sanchez, 1999; Angerosa et al., 2001; Ranalli et al., 2001). Also, although in CPAO the effects of the extraction technology on phenols and the aromatic compound content have not yet been investigated, we would expect to find a similar impact due to its similarity with EVOO. In this respect, we should therefore consider that the latest innovation introduced in the EVOO extraction technology by Alfa Laval could also be applied succesfully to CPAO.

In particular, a recent innovation, such as the hermetic sealed malaxer (Alfa Laval Atmosphera), makes it possible to ensure a perfect control of the head space gas in contact with the mash. This technology reduces the negative effects caused by a prolonged contact of the mash with oxygen and improves volatile compounds and the phenolic content in EVOO (Amirante et al., 2003; Servili et al., 2003a, 2003b). Moreover, very recently, Alfa Laval has introduced an heat exchanger for the olive paste which can make a flash thermal conditioning named EVOO-Line (Figure 4C). Thermal conditioning makes it possible to heat the mash after crushing and before kneading with the positive effect of increasing volatile compounds and reducing kneading time up to 50% (Esposto et al., 2013; Selvaggini et al., 2014). Because of the strong similarities between EVOO and CPAO, we believe that the positive effect of the Atmosphera malaxer and the EVOO-Line flash thermal technology reported in EVOO exctraction could also apply to CPAO and deserves being further explored.

Oil extraction

The separation of oil from solid and liquid phases is done using a decanter centrifuge (Figure 4E). This device exploits the centripetal acceleration to separate continuously a mixture of particulate solids and liquids with phases having different densities (Madsen, 1989). Alfa Laval found that the best decanter centrifuge applicable to CPAO extraction is the three outlet version. In this machine, the mash coming from kneading is fed into the machine together with about 10-20% of hot water (at the same temperature as the mash) depending on the characteristics of product. The mash inside the centrifuge is separated into oil, vegetation water and solids (exhausted pulp and residual skin). Exctraction is carried out in a continous system and can be continuously adjusted thanks to a particular Alfa Laval design with variable dynamic pressure (Amirante and Catalano, 2000; Catalano et al., 2003). This innovation enables us to perform a real-time adjustment of the differential speed between drums and conveyors (Dn), and feed rate according to the characteristics of the raw material with high flexibility, a high level of oil clarification and reduced water consumption (Amirante et al., 2010b). The oil phase and the water phase are collected separately under the decanter. The oil phase is pumped out to a vertical purifier centrifuge, while the water phase is pumped out to a vertical concentrator centrifuge.

Oil purification and recovery

The CPAO flowing from the decanter still has a certain amount of water and solids. Vegetation water from the decanter should still contain a small quantity of residual oil. Both liquid phases are sent to vertical centrifuges (Figure 4F), as already described for the EVOO extraction process (Uceda et al., 2006). The system consists of a disk stack centrifuge for final CPAO purification to remove residual water and solids. A second disk stack centrifuge should be used to recover residual CPAO from the vegetation water flowing from the decanter. The latest improvement of the Alfa Laval decanter technology with three outlets reduces to almost 0% the residual oil in the water. Hence, the use of the centrifuge to recover a very limited quantity of CPAO from vegetation water should be evaluated according to economic constraints.

Process parameters, extraction rates and oil quality with the cold-pressed extraction method

As described above, the characteristics of avocado fruits can change depending on multiple variables. Variety, ripeness stage, geographical area, fruit humidity are some of main factors that affect extraction rates and the final quality of CPAO. The main quantity of oil is in the pulp of the avocado fruit (Lewis et al., 1978; Jacobsberg, 1988). The avocado oil content in the pulp in terms of dry matter shows high genetical and ecological variability (Frega et al., 1990; Shengzhong et al., 1998; Gomez-Lopez, 1999; Bora et al., 2001). From the experimental studies made in New Zealand, the extraction rates vary during the season, because the absolute oil content changes, and typically vary from 10 to 18% of whole fruit. Table 2 shows an example of different oil yields of CPAO extraction depending on different process parameters and show that in practice the yield depends significantly on fruit ripeness. It seems that the theoretical oil content in the fruit can be as high as 22% w/w, yet the current system can extract only 15-16% with a malaxing time not exceeding 90 min and a temperature below 50°C. Wong et al. (2010) reported that the avocado oil yield obtained in New Zealand with the cold pressing system can range from 15% to approximately 25%, depending on whether the fruits are in the early ripening stage or are fully ripen. In this respect, the extractability of CPAO should not differ significantly from that of EVOO (Beltran et al., 2003). However further scientific investigation on this aspect, preferably on the industrial scale, is needed to have a better characterisation of the individual varieties, ripeness stages and process parameters of CPAO extraction plant.

CPAO is today commercialised all over the world. In order to ensure good CPAO quality, Woolf et al. (2009) propose the use of an extra virgin label based on a standard definition, quality indicators, composition and sensory properties. CPAO named also extra virgin avocado oil (EVAO) is defined as oil extracted from high-quality fruits (with minimal levels of rots and physiological disorders). Extraction should be carried out using only mechanical methods including presses, decanters and screw presses at low temperatures (<50°C). The addition of water processing aids (e.g., enzymes and talcum powder) is acceptable, but no chemical solvents can be used. The chemical composition and organoleptic profile of extra virgin avocado oil are reported in Table 3 (Woolf et al., 2009). The flavour of CPAO or EVAO is also described differently, as it varies depending on the cultivar. The Hass cultivar gives an avocado oil with grassy and buttery/mushroom-like flavours. Other varieties may produce oils with a slightly different flavour profiles, as it can be seen with the Fuerte cultivar that has a more mushroomy flavour and fewer typical avocado flavours (Wong et al., 2010). The reported parameters refer to an edible high-quality oil that can be used for salad dressings and is comparable with EVOO. The cold-pressing extraction method described above compared with traditional methods can yield an oil with significantly higher pigment levels, a stronger flavour and, consequentely higher health benefits (Eyres et al., 2001; Birbek, 2002). Moreover, the high content of monounsaturated fatty acids in the CPAO extracted from the Hass cultivar has a high smoke point (≥250°C), making it suitable for frying. Definitevely CPAO is a food comparable with high-quality EVOO, which is at the basis of the Mediterranean diet.

Conclusions

The cultivation of avocado fruits is continuosly growing as is the knowledge about its healthy effects and its consumption. The intuition of New Zealand companies in the late 1990’s with the application of the cold pressing extraction method inspired by EVOO production has led to the introduction of a completely new food oil that is significantly important for its role in cooking and its health-related benefits. Over the last fifteen years, CPAO production has spread in many different countries and its market is set to grow futher also due to the increasing interest in high-quality and healthy fruits. Both CPAO and EVOO are extracted from the fruit pulp and share some basic principles of the production process. Since the characteristics of EVOO have been investigated in depth and correlated to agronomical and technological factors (Costagli, 2006), the same is recommended for CPAO which could offer an unexplored and wide range of potential flavours and characteristics. Moreover EVOO is an object of continuous research to keep improving its production technology, thus leading to a potential improvement in its overall quality (Clodoveo, 2013; Clodoveo et al., 2014). Furthermore, the same approach to technological development adopted for EVOO should be applied to CPAO so as to guarantee its continuous improvement and, consequentely, a growing market potential and spread around the world in the future.


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