Phytochemicals and Antioxidant Activity of Citrus Seed Oils

Abstract

Citrus seeds represent substantial wastes of citrus-processing. Oils extracted from orange (Citrus sinensis), lemon (Citrus limon) and tangerine (Citrus reticulata) seeds were investigated. The seeds were removed from the fruits, washed, dried at room temperature, ground and the oils extracted using a Soxhlet extractor. The seed oils were analyzed in terms of the lipid content, fatty acid, tocopherol and carotenoid compositions, total phenolic content, oxidative stability and the radical-scavenging activity. The oil content of citrus seeds ranged from 34.92 to 41.66%. The oils showed high degrees of unsaturation and essential fatty acids. Oils exhibited also natural antioxidants specially tocopherols and phenolic compounds. Oxidative stability and antioxidant activity were influenced by unsaturated fatty acids and tocopherol contents in the analyzed oils.Keywords: orange, lemon, tangerine, fatty acid, antioxidants *To whom correspondence should be addressed. E-mail: njorge@ibilce.unesp.br IntroductionThe genus Citrus, belonging to the Rutaceae family, is characterized by evergreen, small trees or shrubs, often spiny. The Rutaceae comprises about 150 genera and 1,500 species including some of the most cultivated and consumed fruits of the world, such as C. sinensis (orange), C. reticulata (tangerine), C. paradisi (grapefruit), C. limon (lemon) and C. aurantifolia (lime). These fruits, probably of Southeast Asian origin, are produced all around the world in many countries that have tropical and subtropical climates (Kale and Adsule, 1995).Brazil is one of the biggest global hubs in producing fruits, especially citrus. São Paulo state stands out for the cultivation of orange, lemon and tangerine. Great part of their production intends for juice making, which generates tons of waste, such as seeds that are often disposed, and thus increasing environmental pollution.Besides a large scale in natura consumption, vast quantities of citrus fruits are processed mainly to obtain juice, but also, in the canning industry, to produce marmalade, and by the chemical industry to extract flavonoids and essential oils. Wastes from industrial processing are composed of peels, seeds and pulps representing 45 to 58% of the raw processed fruit (El-Adawy et al., 1999).Several phytochemicals may be detected in edible seed oils including tocopherols, carotenoids, phenolic and polyphenolic compounds, and special fatty acids such as α-linolenic acid. In addition to the phytochemical components, other important oil properties include oil stability and antioxidant activity.Citrus seeds contain from 26 to 42% of oil and are a good source of K, Ca, Na, Fe and Mg (El-Adawy et al., 1999). Saïdani et al. (2004) verified that oils extracted from Tunisian citrus seeds are mostly constituted of triacylglycerols that are rich in unsaturated fatty acids. Oils from citrus seeds native to Pakistan also showed to be an important source of essential fatty acids and tocopherols showing good potential for both human consumption and industrial applications (...

Effects of microwave roasting on the yield and composition of cold pressed orange seed oils

“…Moreover, it is clear that the antioxidant capacity/phenolic content (ac/pc) ratios of both seed oils (3.053 and 2.944) were not very different. The total phenolic content (as mg GAE/100 g oil) of orange seed oil was reported as 115288 (Malacrida et al, 2012). This value is significantly higher than we measured in our samples.…”

“…Specifically, some studies exist in the literature indicating the oil content, oil composition and main oil properties of citrus seeds including orange seeds (Abdel-Rahman, 1980;Habib et al, 1986;Lazos and Servos, 1988;El-Adawy et al, 1999a;Saidani et al, 2004;Malacrida et al, 2012;Matthaus and Özcan, 2012). Saidani et al (2004) have reported around 34% and 51.8% oil in blood and sweet orange seeds, respectively.…”

“…Around 53.800 tons for juice and 2.700 tons for juice concentrate were processed in the same year in Turkey (TUIK, 2014). It is well known that around 3-5% of the fruit weight comes from seeds (Malacrida et al, 2012), and around 1.500-3.000 tons of orange seeds are generated annualy in Turkey. Since the amount of oranges used for juice production is continually increasing, the amount of seeds generated is increasing steadily.…”

“…This value is significantly higher than we measured in our samples. Furthermore, Malacrida et al (2012) reported 47.6% quenching ability for the DPPH radical of orange seed oil, and indicated that the highest antioxidant capacity was in orange seed oil compared with lemon and tangerine seed oils. Unfortunately, there is no other data available in the literature to compare with our findings.…”

Physico-chemical Characterization of Seed Oils Extracted from Oranges (Citrus sinensis)

“…The seed oil of orange had considerable amounts of oleic fatty acid, with oil-seeds Pera-rio highest value obtained, 29.31%. These results agree well with those reported by Malacrida et al (2012) for orange, lemon and tangerine seed oils, 23.04, 20.80 and 27.78%, respectively. Regarding the fatty acid α-linolenic acid, oils from orange seeds showed percentages of 2.10% for Valencia variety, 2.30% for Hamlin, 2.75%, for Pera-rio and 2.76% for Natal. Taking into account the percentage of this fatty acid in rice bran oil (0.1 to 2.9%), the seed oils of oranges have consistent amounts of this fatty acid (Codex Alimentarium Commission, 2009).…”