Keywords

1 Genus Opuntia as a Source of Seed Oil

The genus Opuntia generally called the cactus pear, or prickly pear belongs to Cactaceae plant family that includes approximately 130 genera with about 1500 species (Guedes Paiva et al., 2016). They are native to Mexico and widespread throughout Central and South America, Australia, Africa, including the Mediterranean area (Ammar et al., 2014; Shedbalkar et al., 2010). Mexico has the highest genetic diversity of Opuntia spp. with 150–180 species, of which O. hyptiacantha F.A.C. Weber, O. leucotricha DC., O. megacantha Salm-Dyck, and O. streptacantha Lem. are the most common species (Martínez-Tagüeña & Trujillo, 2020). Opuntia spp. are cultivated over a broad range in latitude, and it is growing in areas ranging from the sea level to a height of 5100 m (Guedes Paiva et al., 2016). Opuntia tends to favor dry, hot areas inhabited with perennial shrubs, trees, and creeping plants (Shedbalkar et al., 2010). The several varieties of the commonly researched O. ficus-indica (L.) Mill. are distinguished by characteristics such as having spiny or spineless cladodes, a cladode shape, branching, its fruit and pulp color, epicuticular wax morphology with sweet pulp and limited acidity, and variable weight of the fruit ranging from 43 to 220 g (Ayadi et al., 2009; Medina-Torres et al., 2013; Guedes Paiva et al., 2016; Cota-Sanchez, 2016). This cactus plant’s fruit is elongated and oval, with the pulp containing hard seeds (Piga, 2004). The seeds that are a waste product after pulp extraction and conversion can extract edible oil with unique properties. Opuntia seed oil has a high content of unsaturated fatty acids (especially polyunsaturated), dominated by linoleic acid and tocopherols, particularly γ-tocopherol (Stintzing et al., 2001; Simopoulos, 2002; Chahdoura et al., 2015). The favorable physicochemical characteristics of the oil allow it to be easily applied for various commercial applications. Although the oil is edible, its presence in the food industry is not very common and has instead entered the cosmetics industry’s niche market. Some years ago, the prickly pear plant drew the research community’s attention due to its potential versatile economic applications from the pericarp, pulp to its seeds, and its unique composition of several beneficial compounds (Piga, 2004; Ciriminna et al., 2017). This chapter is intended to provide insight into the published data on Opuntia seed oil, particularly their extraction methods and yields, physicochemical properties, fatty acid composition, tocopherol, sterol composition, and their potential application in the health and cosmetic sectors.

2 Extraction Methods and Yields

The extraction methods for obtaining Opuntia seed oil include cold pressing, organic solvents, supercritical carbon dioxide (scCO2), and ultrasound extractions. Table 33.1 summarizes reported extraction methods and their oil yields obtained from Opuntia species and their sampling locations. The Opuntia fruit is composed of about 2–12% seeds with an approximate weight of 67–216 g (El Kossori et al., 1998; Piga, 2004; Karabagias et al., 2020) and about 0.24 seeds/g fruit pulp (De Wit et al., 2016; Ciriminna et al., 2017). The general preparation method in obtaining the seeds for oil extraction include the following steps (Chougui et al., 2013; Ghazi et al., 2013; Ramírez-Moreno et al., 2017; Belviranlı et al., 2019; Regalado-Rentería et al., 2020):

  1. 1.

    Undamaged and ripe/mature Opuntia fruits are harvested and peeled manually,

  2. 2.

    Fruit is homogenized or liquefied to obtain the fruit pulp containing the seeds,

  3. 3.

    Fruit pulp is sieved or sifted to remove seeds from the pulp,

  4. 4.

    Seeds are then washed with water and dried (sun-dried/room temperature or drying at 60 °C until constant mass), and then

  5. 5.

    Seeds are grounded and used for oil extraction.

Table 33.1 Extraction methods and yields of Opuntia seed oil (%)
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The oil yield from a species of Opuntia collected from different areas within a region can vary (Matthaüs & Özcan, 2011). Similarly, harvesting times have been shown to affect the oil content of O. ficus-barbarica A. Berger from Turkey (Al Juhaimi et al., 2020). Oil content ranged from 3.09% to 6.80% for sample collected from June to August (Al Juhaimi et al., 2020). The use of supercritical carbon dioxide (46.51 °C, 46.96 MPa, 10 kg CO2/h for 2.79 h) in the extraction of seed oil from O. dillenii Haw. resulted in an optimum yield of 6.65% (Liu et al., 2009). The ultrasound extraction method has also been applied to extract oil from O. ficus indica, Reyna variety, from Mexico (Ortega-Ortega et al., 2017a). The yield of oil was shown to be proportional to the amplitude level (Ortega-Ortega et al., 2017a). Generally, the oil yield of Opuntia species varies from 1% to 20% depending on species, cultivation/growing area, extraction methods, and harvesting times (Table 33.1). Cold pressing produces about 1 L oil from 800 to 1000 kg fruits or 25 kg seeds (Prakash & Sharma, 2014; Mule, 2016), while the use of organic solvents produces a higher oil yield. Green extraction technologies are more favored due to the adverse health and environmental issues associated with organic solvents (Koubaa et al., 2017). Oil extracted from O. ficus-indica from Tunisia was reported to be of better quality than the oil extracted with Soxhlet with n-hexane (Yeddes et al., 2012). The use of scCO2 and cold pressing extraction technologies are preferred in terms of the oil’s application in cosmetics and health products (Koubaa et al., 2017).

3 Physicochemical Properties

The most-reported physicochemical properties were for O. ficus-indica seed oil, while the physicochemical properties of O. elatior (Mill.) (Bhatt & Nagar, 2013) and O. robusta seed oil (De Wit et al., 2017a) have also been reported (Table 33.2). Opuntia seed oil is an edible oil, with reported low toxicity (Boukeloua et al., 2012), which is light green to yellow (Sawaya & Khan, 1982; Moutkane, 2015) and is a liquid at room temperature (El Mannoubi et al., 2009). The seed oil’s refractive index and density range from 1.4596 to 1.4831 and 0.904–0.907, respectively (Table 33.2). The iodine values range from 111 to 132 g I2/100 g oil, which refers to the high degree of unsaturation in the Opuntia seed oil (Table 33.3). A significant variation in peroxide values of the Opuntia seed oil obtained from different species and their origin have been reported (Table 33.2). The peroxide values recorded are low and indicate the oil’s oxidative stability and quality (Table 33.2). The seed oil has low acid values, and saponification values ranging from 173 to 222 mg KOH/g oil. The unsaponifiable matter ranges from 1.19% to 2.65%. The physicochemical properties have been shown to vary among Opuntia seed oils obtained from different cultivars (De Wit et al., 2017a). O. ficus-indica seed oil from Greece has been reported (Karabagias et al., 2020) to be rich in aroma due to the presence of a wide range of organic compounds and, in particular, volatile compounds. The aroma is described to be of a floral and fruity nature (Moutkane, 2015). The oil has been reported to be stable for about 18 months, if kept under prescribed storage conditions (Moutkane, 2015).

Table 33.2 Physicochemical characteristics of Opuntia seed oil
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Table 33.3 Fatty acid composition (%) of Opuntia seed oil
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4 Fatty Acid Composition

The main species for which the fatty acid composition of the seed oil has been reported are O. ficus-indica; others include O. streptacantha, O. robusta, O. boldinghii, O. joconostle, O. matudae, O. elatior, O. dillenii, O. albicarpa, O. ficus-barbarica, O. aequatorialis, O. leucotricha and O. megacantha (Table 33.3). The dominant fatty acid found in the Opuntia seed oil is linoleic acid in a concentration range of 56–77%, followed by palmitic acid (9–23%) and oleic acid (2–29%) (Table 33.3). Other fatty acids found in minor concentrations are myristic acid, palmitoleic acid, stearic acid, linolenic acid, and behenic acid, depending on the origin of the species and the specific species cultivar of Opuntia. The fatty acid composition of Opuntia seed oil is similar to that of the sunflower and grape seed oils (Labuschagne & Hugo, 2010; El-Mostafa et al., 2014). The content of linoleic acid in Opuntia seed oil is higher than that reported for argan oil (El-Mostafa et al., 2014). The fatty acid composition in Opuntia species collected from different areas within a region can vary (Matthaüs & Özcan, 2011; Ramadan & Mörsel, 2003). Similarly, harvesting times have been shown to affect the oil content of O. ficus-barbarica A. Berger from Turkey (Al Juhaimi et al., 2020). Plant genetics, soil conditions, and climate conditions influence the composition of fatty acids of Opuntia seeds oil (Matthaüs & Özcan, 2011; Ramadan & Mörsel, 2003). The fatty acid composition of seed oil from O. ficus-indica, Sanguigna (red) variety, and O. ficus-indica, Surfarina (yellow) variety of Italy is not affected by the extraction procedure used such as Soxhlet (n-hexane) and ultrasound-assisted maceration procedure (Loizzo et al., 2019). O. megacantha Salm-dyck seed oil has been reported to contain a higher linoleic acid content as compared to argan and olive oil (El Kharrassi et al., 2018). The eicosadienoic acid (C20:2, 1.7%), an omega-6 fatty acid, has been reported by Bhatt and Nagar (2013) to be contained in O. elatior (Mill.) from India. O. ficus-indica seed oil from Tunisia has been found (El Mannoubi et al., 2009) to contain 5% of vaccenic acid (18:1n-7).

5 Tocopherol and Sterol Composition

The most common species for which the tocopherol composition of Opuntia’s seed oil has been reported is O. ficus-indica from markets such as Germany, Tunisia, Turkey, Morocco, and Italy. At the same time, other species also include O. dillenii (Morocco), O. megacantha (Mexico), O. albicarpa (Mexico), O. streptacantha, O. robusta (Mexico), O. matudae (Mexico), O. aequatorialis (Morocco), and O. leucotricha (Morocco). Table 33.4 provides an overview of the tocopherol composition of the seed oil from various species of Opuntia. The reported dominant sterol is γ-tocopherol, while α, β, δ-tocopherol have been reported to be present in some Opuntia seed oils. Tocopherols such as α-tocopherol, ∝-tocopherol, δ-tocopherol, α-tocotrienol, ∝-tocotrienol, plastochromanol-8, γ-tocotrienol, and δ-tocotrienol were not detected in O. ficus-indica L. seed oil from Turkey (Matthaüs & Özcan, 2011). The geographical location affects the composition and concentration of tocopherol in Opuntia seed oil (Matthaüs & Özcan, 2011; Taoufik et al., 2015). The γ-tocopherol content of seed oil from O. ficus-indica, Sanguigna (red) variety and O. ficus-indica, Surfarina (yellow) variety of Italy is reported to be affected by the extraction procedure, wherein Soxhlet (n-hexane) extracted a higher content as compared to the ultrasound-assisted maceration procedure (Loizzo et al., 2019). O. megacantha Salm-dyck seed oil contains mainly β-tocopherol and γ-tocopherol (El Kharrassi et al., 2018). Various sterols are found in Opuntia seed oil, with ∝-sitosterol as the most dominant sterol (Table 33.5). The sterol, fucosterol, has been detected in the seed oil obtained from O. dillenii from Morocco (Ghazi et al., 2013). Stigmastanol (47 mg/100 g) has been found in the seed oil of O. ficus-indica from Algeria (Brahmi et al., 2020). Regalado-Rentería et al. (2020) reported the presence of the squalene in the seed oil of O. megacantha, O. albicarpa, O. streptacantha, O. robusta, and O. matudae from Mexico.

Table 33.4 Tocopherol of Opuntia seed oil (mg/100 g)a
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Table 33.5 Sterol compositions of Opuntia seed oil (mg/100 g)a
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6 Health and Cosmetic Applications

Opuntia seed oil has been reported to have a wide range of health applications (Table 33.6), which include antimicrobial and antifungal activities, analgesic and anti-inflammatory effects, 𝛼-glucosidase inhibitory activity and cytotoxicity against certain cancer cell lines from the human origin (Ramírez-Moreno et al., 2017; Villacís-Chiriboga et al., 2020). Table 33.5 provides a summary of the health benefits of Opuntia seed oil and their potential industrial applications. The seeds of prickly pear have been reported to have antioxidant activity towards lipid peroxidation (González-Stuart & Rivera, 2019). The seeds of O. ficus-indica are also reported to be used in traditional medicine (Boukeloua et al., 2012). The antioxidant ability and hypoglycemic effect of seed oils from O. ficus-indica, Sanguigna (red) variety, and O. ficus-indica, Surfarina (yellow) variety of Italy have been demonstrated by Loizzo et al. (2019). O. albicarpa and O. ficus-indica from Mexico are useful as antimicrobials and antioxidants (Ramírez-Moreno et al., 2017). The presence of phenolic compounds and tocopherols in the oil contributes to the good antioxidant activity because these compounds are capable of influencing cellular responses to various oxidative stresses via modulating signal-transduction pathways (Eckardt, 2008; Maeda et al., 2008). The consumption of oil has been associated with a reduced risk of developing cardiovascular, inflammatory, and autoimmune diseases (Chahdoura et al., 2017). O. ficus-indica seed oil was reported to have hypocholesterolemic and hypolipidemic activities (Ennouri et al., 2007). Cactus pear seed oil has also been reported to have the ability to prevent alloxan-induced-diabetes by quenching free radicals produced by alloxan and inhibiting tissue injuries in pancreatic β cells (Berraaouan et al., 2015). Cold pressed Opuntia seeds oil extracted from O. ficus-indica (Morocco) is useful in treating diabetes mellitus (Berraaouan et al., 2015). The Opuntia seed oil has been applied in encapsulating vitamin A towards the use as a topical delivery system of vitamin A (Al Zahabi et al., 2019). The dominant presence of linoleic acid at a high concentration in Opuntia seed oil (Table 33.3) also contributes to the oil’s health benefits (Soel et al., 2007). The health benefits and antioxidant potential of phenolic compounds is well reported. Chbani et al. (2020) have suggested developing a phenolic compound composition fingerprint to detect adulteration and authenticity of the Opuntia seed oil. The dominant phenolic compounds in the seed oil of O. ficus-indica from Morocco are ferulaldehyde, vanillin, and syringaldehyde. Roasting of seeds before oil extraction resulted in differences in phenolic compounds’ composition, except vanillin (Chbani et al., 2020).

Table 33.6 Health applications of Opuntia seed oil
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Opuntia seed oil is a beneficial oil widely advertised for skincare applications (Argan Oil Direct, 2020). It is marketed as oil with good hydration potential, anti-aging and antioxidant potential, improved skin elasticity, and the ability to reduce skin redness and pigmentation (Joslin, 2017; Opuntia Luxury Oils, 2020; Argan Oil Direct, 2020). The oil has a ratio of 3:1 of linoleic to oleic acid, making it suitable for cosmetic applications (Opuntia Luxury oils). The oil’s antimicrobial ability makes it suitable to develop skincare products to treat acne (Healthline, 2020). The oil is reported to contain vitamin K1 (0.53 g/kg) that provides the oil with the ability to reduce dark/under-eye circles and spider veins (Ramadan & Mörsel, 2003; Argan Oil Direct, 2020; Daya, 2020). The oil is non-greasy and easily absorbed onto the skin. While the direct application of Opuntia seed oil on the skin is known, the oil is also used as a carrier oil to produce other cosmetic products (Healthline, 2020). Opuntia seed oil is also applied in hair products (Argan Oil Direct, 2020), with some treatments have been patented (Battermann & Thomas, 2014).

7 Conclusion

Opuntia seed oil can be obtained from a wide range of different species and cultivars of Opuntia worldwide. Harvesting times, geographical locations, and species type or cultivar affect the biochemistry of Opuntia seed oil. In terms of its chemical composition, it is considered safe with various health benefits. The oil is actively promoted in the cosmetics industry, but there is a great potential for developing cosmeceuticals and nutraceuticals from Opuntia seed oil.