ABSTRACT
Oil was extracted from carica papaya (pawpaw) seeds and analyzed for its physico-chemical properties (percentage of oil yield, moisture content, pH, specific gravity, acid value, saponification value, ester value, iodine value, peroxide value and unsaponifiable matter) and sensory qualities (colour, aroma, taste and general acceptability). The sensory characteristics analyzed by the panelists on the three oil samples (pawpaw, olive and vegetable oil) gave preference for the vegetable oil in all the attributes.
CHAPTER ONE
INTRODUCTION
1.1 Background to the Study
Among the most important tropical fruit grown in the world nowadays and in the country, papaya (Carica papaya L.) occupies a prominent place (WHO, 2010). Native to tropical America, the papaya has spread to several regions of the world, and its largest producers are Brazil, Mexico, Nigeria and India. Brazil is responsible for 12.74% of world production. The world production has a harvested area of 441,042 ha and 12,420,585 tons worldwide in the year of 2013. Nowadays, Brazil is the second largest fruit producer, producing over 1,517,696 tons/year, only behind India (WHO, 2010; Embrapa, 2013). The papaya tree is typically tropical, semi-herbaceous stem, hollow, cylindrical and simple. It grows fast and can reach 8 feet tall. This is a fleshy fruit, large, indehiscent, with pulp soft, dense, aromatic and has different colors that vary from yellow to red. The bark is smooth and thin, green when harvested and becomes gradually yellow or orange during ripening. The internal cavity of the fruit contains numerous black seeds, edible, spicy flavor, coated with a mucilaginous substance (Gomes, 2007). This fruit is preferably consumed fresh, while offering many products and by-products through industrialization. Its pulp has organoleptic properties (texture, color and aroma), chemical (total soluble solids, acidity and good balance of sugars and organic acids) and digestive, making it an ideal food for healthy people of all ages (Medina et al., 1989). The fruit of Carica papaya L. (papaya), rich in vitamins A, B and C, has also as constituents carbohydrates, proteins, alkaloids (carpaine and pseudocarpaine), proteolytic enzymes (papain and quimiopapain), and benzyl isothiocyanate, more known as BITC, which has anthelmintic activity (Kermanshai et al., 2001).
The seeds of papaya fruits are generally discarded. However, in order to make a more efficient use of papaya, it is worth investigating the use of the seeds as a source of oil. A compound present in crushed papaya seed that is believed to have activity against helminthes intestinal parasites, benzyl isothiocynate, has been shown to have an effect on vascular contraction using a canine carotid artery in vitro model (Wilson and Kwan, 2002). Papaya seed oil utilized in high amount such oils could lead to reduced risk of coronary heart disease. In addition, high oleic oil has sufficiently stability be used in demanding application such as frying. Area of spray oil for snacks, crackers, cereal dried fruit, bakery products where the oil is used to maintain product quality and to increase palatability. Papaya seed oil can be considered as high oleic oil and hence viewed as a healthy alternative to many other vegetable oils (Corbett, et al 2003).
The extraction and use of vegetable oils has for centuries played an important role in the manufacture of a large number of industrial products and food items. Currently, two main processes for the extraction of oil from seeds are of industrial importance: the hydraulic process and further purification and the chemical process using organic solvents (McGlone et al. 1986). This latter process for extracting oil from seeds, although giving high oil extraction recovery, requires expensive capital investment and operational costs and causes undesirable effects on the quality of end products because of the high temperatures used in the process (Christensen, et al, 1991). There is also an older process of aqueous extraction that is advantageous, because it presents no risk of fire or explosion, is nontoxic and the mild processing ensures high quality products (Dominguez et al. 1995). The operation is also more flexible with less initial investment and operational costs. The main disadvantages, as compared to conventional technologies, are lower efficiency of oil extraction and the reduction of product stability, leading to easier microbial contamination. Aqueous extraction, on the other hand, yields not more than 35% of the oil content of the seed (Tano-Debrah and Ohta 1994).
Considering their widespread applications, these processes thus contribute to major losses of fats and oils in the world’s food production system. This is an issue worth considering as efforts are intensified to increase fat and oil production to meet the quickly growing global demands (Tano-Debrah and Ohta 1995a). With rising value for oils and with demands for better oil quality, coupled with several years of unfavorable climate conditions in growing regions, there has been a noticeable increase in trials using enzymes for processing a wide variety of oil sources including palm, olive, soybean, rapeseed, sunflower seed, cottonseed, corn germ and groundnut (Godfrey and Reichelt 1983). The use of enzymes shows some improvement in the yield of oil, together with a reduction in the acid development and oxidation of the oil during further processing and storage. Also, there is a reduction in undesirable side products and in waste treatment costs (Dominguez et al. 1994). Much research has been done on enzyme-assisted oil extraction from various seeds such as sunflower kernel (Dominguez et al. 1995), shea tree (Tano-Debrah and Ohta 1994, 1995a), canola, cocoa beans (Tano-Debrah and Ohta 1995b) and coconut (McGlone et al. 1986; Tano-Debrah and Ohta 1997).
1.2 Statement of the Research Problem
Among the most important tropical fruit grown in the world today, papaya occupies a prominent place. Native to tropical America, papaya has spread to several regions of the world. Pawpaw seeds are normally discarded and assumed to be a waste product, but the oil from the seed of pawpaw has been reported to be useful in pharmaceutical industries, consumerist soaps, textile and detergent industries. These has promoted for a study to be carried out on the extraction and characterization of oil from pawpaw seed.
1.3 Aims/Objectives of the Study
The study sought to evaluate the extraction and characterization of oils from pawpaw seed. Specifically, the study sought to;
- examine the factors affecting rate of leaching and factor governing choice of solvent
- examine the different methods of oil extraction.
- evaluate the composition of pawpaw (carica papaya) seed oil.
1.4 Significance of the Study
This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study will contribute to knowledge and could serve as a guide for other study.
1.7 Scope of the Study
This study is on extraction and characterization of oils from pawpaw seed. The papaya seed oil will be extracted by solvent extraction method and the characteristic of seed oil will be studied.
References
Corbett P (2003). It’s time for an oil change, opportunities of high oleic vegetable oils.Inform 003; 14:12:62-76.
Empresa Brasileira de Pesquisa Agropecuária (Embrapa), available in: http://www.cnpmf.embrapa.br/index.php?p=pesquisa-culturas_pesquisadasmamao.php&menu=2 (2013).
J.C. Medina, E.W. Bleinroth, J.M.M. Sigrist, Z.J. De Martin, A.L.A.C. Nisida, V.L.S. Baldini, R.S.S.F. Leite, A.E.B. Garcia, Mamão:cultura, matéria-prima, processamento e aspectos econômicos. 2nd edition (1989) p. 1–178.
Mcglone, O.C., Lopez-Munguia, C. And Carter, J.C.(1986). Coconut Oil extraction by of shea fat: A rural approach. J. Am. Oil Chem. Soc. 72, 251–256.
- Gomes, Fruticultura Brasileira, São Paulo: Nobel, 13rd edition (2007) p. 300– 307.
- Kermanshai, B.E. McCarry, J. Rosenfeld, P.S. Summers, E.A. Weretilnyk, G.J. Sorger, Benzyl isothiocyanate is the chief or sole anthelmintic inpapaya seed extracts, Phytochemistry 57 (2001) 427–435.
Wilson and Kwan (2002).effects of papaya seed extract and benzyl isothiocynate on vascular contraction. Life sci 2002; 71:497-507.
World Health Organization (WHO), available in: http://www.who.int/whopes/resources/resources_2010/en/index.html (2010)
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