LITERATURE REVIEW
Legumes, broadly defined by their unusual flower
structure, podded fruit, and the ability of 88% of the specials examined to
date to form nodules with rihzobia (de Faira et al; 1989). They are second only to the graminiae in their
importance to human. Legumes belongs to the family Leguminosae in the
tropics, they are the next important food crop after cereal. (Uzoechina, 2009)
They are sources of low-cost dietary vegetable proteins and minerals when compared
with animal products such as meat, fish and egg (Apata and Ologhobo, 1997).
Indigenous Legumes therefore are an important source of affordable alterative
protein to poor resource people in many tropical countries (Ihekoronye A.I and
Ngoddy P.O 1985). Legumes have historically been part of expensive meals
throughout the world as they have a major role in the fight against
malnutrition. It is therefore necessary that their levels of consumption, which
are already too low in a number of developing countries be increased (Borget,
M. 1992). Legumes serves as a source of non-processed protein for rural and
urban dwellers of the population especially in the poor countries of the world
(Rachie, K.O and P. Silvestre, 1977) and as a good source of fibre, resistant
starch, and other nutrients, they are one of the least glycemic sources of
carbohydrates, because the starch is either slowly absorbed or resistant.
Tropical developing countries are facing an increasing demand for protein- rich
food due to teeming population, cereal based diet and scarcity of fertile land
(Sadik, 1991, Weaaver, 1994). Legumes are an in expensive source of proteins
with desirable characteristic such as abundance of carbohydrates, ability to
lower the serum cholesterol, high fibre low fat (except oilseeds),. high
concentration of poly unsaturated fatly acids and a long shelf life. In
addition to B complex vitamins, minerals and fibre, Legumes are also major
sources of proteins and calories (Rockland and Nishi, 1979). They are know to contain
certain bioactve compounds whose beneficial effects need to be explored for
exploitation. The global production of food Legumes in 1998 was 246 million
tons (FAQ, 1998). Legumes are sources of carbohydrates, minerals, dietary fibres
and water soluble vitamins which are important in human health.
NUTRITIVE
VALUE OF LEGUMES
The nutritive value of a diet depends on the
proportion of nutrients digested (digestibility) and on the efficiency with
which these digested nutrients are absorbed and utilized with in animal
tissues, demonstrated that the high nutritive value of Legumes is probably due
to increased protein absorption which results in a better balanced of absorbed
nutrients. (Ulyatt and Macrae 1974) Bloat, which is mainly caused by the formation
of a stable protein foam in the rumen, is still a major problem with cattle fed
Legumes. It has been observed that bloat does not occur when certain Legumes
such as lotus and sainfoin are fed to cattle. This has been correlated with the
presence of a class of compounds known as condensed tanning in these Legumes
(Jones and Lyttleton, 1971; Reid et al; 1974). Sodium is often low in Legumes.
Indeed sodium deficiency can limit animals production from Lucerne in the
central North Island (Joyce and Brunswick, 1975).
Although the nutritive characteristics of Legumes are
good, they are often associated with animal disorders such as bloat (Reid,
1960, Gurnsey et at; 1977). The
Ability of pasture Legumes to fix nitrogen and to produce large quantities of
herbage is well known it is also generally recognized that the feeding value of
Legumes is superior to that of most grasses and graminaceous forage. The best
known example is the superior feeding value of white clover (Sinclair et at; 1956; Mclean et al; 1962).
THE POTENTIAL HEALTH BENEFITS OF LEGUMES AS A GOOD
SOURCE OF DIETARY FIBRE.
Dietary fibre has been shown to have important health
implications in the prevention of risks of chronic diseases such as cancer, CVD
and diabetes mellitus. It comes from the family of carbohydrates, an NSP, not
digested in the small intestine but may be fermented in the colon into SCFA
such as acetate, propionate and butyrate. (Roberfroid M 1997). They enhance
water absorption in the colon, and thus prevent constipation. Dietary fibre has
the ability to bind with bile acids and prevents their reabsorption in the
liver, and thus inhibit cholesterol synthesis (Chen WjL, Anderson JW and
Jenkins DJA 1984). Dietary fibres viscous and fibrous structure can control the
release of glucose with time in the blood, thus helping in the proper control
and management of diabetes mellitus and obesity (Wolever TMS, et al . 1982 Creutzfeldt W 1983). LOW-GI
foods, for example, high-dietary fibre foods, have been shown to reduce
postprandial blood glucose and insulin responses and improve the overall blood
glucose and lipid concentrations in normal subjects and patients with diabetes
mellitus (Collier GR, Giudici S, Kalmusky J, et al; 1988, Wolever Tms, Jenkins
DJA, Vuksan V, et al, 1992).
INDUSTRIAL
In addition to traditional food and forage uses,
Legumes can be milled into flour, used to make bread, doughnuts, tortillas,
chips, spreads and extruded snacks (R.Phillips personal communication) or used
in liquid form to produce milks, Yogurt, and infant formula (Garcia et al; 1988). Pop beans (Popenoe et al,
1989, licorice Glycyrrhiza glabra; kindscher, 1992). and soybean candy (Genta et al, 2002) provide novel uses for
specific Legumes.
Legumes have been used industrially to prepare biodegradable plastics (Paetau et al, 1994) oils, gums, dyes, and inks (morn, 1997). Many Legumes have been used in folk medicine (Duke, 1992; Kindscher, 1992). Isoflavones from soybeans and other Legumes have more recently been suggested both to red ice the risks of cancer and to lower serum cholesterol (Kennedy, 1995, Molteni et a, 1995). Soybean and soyfood phytoestrogens have been suggested as possible alternatives to hormone replacement therapy for postmenopausal women.
Legumes have been used industrially to prepare biodegradable plastics (Paetau et al, 1994) oils, gums, dyes, and inks (morn, 1997). Many Legumes have been used in folk medicine (Duke, 1992; Kindscher, 1992). Isoflavones from soybeans and other Legumes have more recently been suggested both to red ice the risks of cancer and to lower serum cholesterol (Kennedy, 1995, Molteni et a, 1995). Soybean and soyfood phytoestrogens have been suggested as possible alternatives to hormone replacement therapy for postmenopausal women.
DIETARY FIBRE PROFILE OF FOOD LEGUMES
Dietary fibre has been recognized as a health
component (Walker, 1998). It consists of a mixture of polymeric non-starch
substances, which resist enzymatic digestion in the human gastrointestinal
tract. Most of these substance are complex carbohydrates like cellulose,
hemi-cellulose and pectin (Toberfroid, 1993) phendic compound, ligin also
constitutes a small portion of dietary fibre (morenol and lopez, 1993).
Health1) benefits associated with adequate intake of these substances include:
lower blood cholesterol and sugar levels, reduced risks of constipation,
obesity, diabetics, heart complications, colon and rectal cancer gallstone,
piles and hernia (ADA, 1997). This health benefits reflects the nutritional
significance of dietary fibre, and have attracted the consumer to fibre rich
foods public health organisaton (WHO, 1986 and NRC, 1989). Also recommended an
increase in the daily consumption of dietary fibre. For theses reasons, the
determination of the dietary fibre content of food has been receiving much
attention for the last few years (Engist et at; 1988, and Pallami et at 1992).
A wide variety of food items have been analyzed for their total dietary fibre
content (Lintas and Cappelloni, 1988, 1ongean et at 1989). Attention has
focused on the dietary fibre content of Legumes (Shaarma, 1986 and vidal
valverde et al, 1992) because of
their effectiveness in lowering blood cholesterol, improving glucose tolerance
and reducing insulin requirements (Anderson et
al. 1984, Tappy et at, 1986 and
Shutter et at 1989) Although the
total dietary fibre (TDF) Content of certain Legumes has been measured, but I variations
in the available data exist, these variations could be regional (soil and
climatic) and genotypic.
However, methodological differences could not be
ignored with the recent development of the novel enzymatic techniques (Prosky
et al. 1988). For dietary fibre determination in foods, increasing interest has
been diverted to the soluble and insoluble components (Hughes, 1991). Legumes
cellulose and some hemi cellulose typically constitute the insoluble dietary
fibre (IDF), where as pectin some hemi cellulose and other non-starch dietary
fibre polysaccharides make up the soluble dietary fibre (SDF) (Roherfroid,
1993). Legumes seeds typically contain more dietary fibre than cereals and are
better sources of metabolically active SDF (Hughes and Swanson, 1989) The
present work was undertaken to assess the dietary fibre profit of grain Legumes
commonly consumed in Pakistan, especially in the North-west frontier province
(NWFO).