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PURIFICATION AND CHARACTERIZATION OF PAPAIN FROM CARICA PAPAYA LATEX: ITS APPLICATION IN THE HYDROLYSIS OF TIGERNUT PROTEIN HOMOGENATE

CHAPTER ONE
INTRODUCTION
Carica papaya, the sole species in the genus Carica of the plant family Caricaceae cultivated
in most countries with tropical climate like Nigeria (Akinloye and Morayo, 2010), is
commonly and erroneously referred to as a “tree”. The plant is properly a large herb growing
at a rate of 6-10 feet in the first year and reaching 20-30 feet in height, with a hollow green or
deep purple stem between 30-40cm or more thick at the base and roughened by leaf scars. It
is a herbaceous soft wooded, typically unbranched, cultivated worldwide in tropical and
subtropical climates, mainly for its melon- like fruits Organisation for Economic Cooperation
and Development (2005). Europeans encountered papaya first in the western Hemisphere
tropics and various interests disseminated it widely (Sauer, 1966; Ferrao, 1992).
Carica papaya Linn is more commonly called pawpaw in Nigeria. The generic name is
derived from the Latin “Carica”, meaning edible fig’, on account of the similarity of their
leaves (Orwa et al., 2009). It has many local names, such as (Fafay, babaya), Arabic, (Bisexual
paw paw, tree, melon tree, papaya) English, French (Papailler, papaya, papaye),
German (Melonbraum), Spanish (Figuera del monte, fruta bomba, papaya) (Orwa et al,
2009). It is known as okwulu bekee by the Igbos, ibepe by the Yoruba and Kawuse by the
Hausa tribes of Nigeria (Abo et al, 2008, Udeh and Nwaehujor, 2013).
1.1 C. Papaya
1.1.1 Origin of C. Papaya
C. papaya, originally is from south Mexico (Udeh and Nwaehujor, 2013). Though opinions
differ on the origin of C. papaya, it is native in northern- tropical western hemisphere
Organisation for Economic Cooperation and Development (2005). It is likely that C. Papaya
originated from the low-lands of East Central America, from Mexico to the Panama
(Nakasone and Paull, 1998). Its seeds were distributed to the Carribean and South-east Asia
during Spanish exploration in the 16th century, from where it spread rapidly to India, the
pacific and Africa (Villegas, 1997). The genus vasconcellea (formerly in carica) is found in
South America along the Andes, especially in Ecuador (Badillo, 1993; Morales Astudillo, et
al., 2004), with outlying species reaching as far as Chile, Mexico, Argentina and Uruguay
(Aradhya et al., 1999; Van Droogenbroeck et al., 2004). This led some to propose South
America as the origin for C. papaya (Prance, 1984). Evidence to the contrary is provided by
finding only domesticated – type feral C. papaya in South America (Manshardt and Zee,
2
1994; Morshidi, 1996), but finding wild plants in Mexico and Honduras (Moreno, 1980;
Manshardl and Zee 1994: Manshardt, 1998; Paz and Vazguez–yanes, 1998). Papaya was
probably domesticated in northern tropical America.

1.1.2 Taxonomy of C. Papaya

Taxonomy is defined as the analysis of an organism’s characteristics for the purpose of
classification. C. papaya is classified as follows:-
Kingdom Plantae
Subkingdom Angiosperms
Division Magnoliophyta
Class Rosids
Order Brassicales
Family Caricaceae
Genus Carica
Species Carica papaya.
(Wikipedia, 2013)
Caricaceae family was thought to comprise 31 species in three genera, namely Carica,
Jacaritia and Jarilla (Nakasone and Paull, 1998). A recent taxonomic revision proposed that
some species formerly assigned to Carica were more appropriately classified in the genus
vasconcellea (Badillo, 2002). However, concensus has been developed that the genus Carica
L. has only one species Caricapapaya, and that Caricacae may contain six genera (Aradhya
et al., 1999; Badillo, 2000; Van Droogenbreeck et al, 2002, 2004; Kubitzki, 2003). Most of
the genera are Neotropical forest plants, occurring in South America and Mesoamerica
andVasconcelleae, the largest genus with 21 species had usually been considered as a section
with Carica. The other members of the genera include Jacaritia (7 Spp). Jarilla (3 Spp),
Horovitaia (1 Spp) (Badillo, 1993), and Cylicomorpha (2 Spp) which occur mainly in
montane forests in equatorial Africa (Badillo, 1971), with Carica papaya the only species
within the genus carica (Badillo, 2001).The highland papaya, vasconcelleae is the closest
relatives to Carica papaya (Badillo, 1993; Aradhya et al, 1999; Van Droogenbroeck et al,
2002, 2004).