EFFECTS OF DIFFERENT TREATMENTS ON THE CHEMICAL CONTENT AND ACCEPTABILITY OF WATER LEAF (TALINUM TRIANGULARE)

PROPERTIES OF VEGETABLES

3.3.2   Blanched waterleaf vegetable

3.4     SOUP PREPARATION

complexiometric titration method)

4.1 PROXIMATE COMPOSITION OF WATERLEAF (Talinum 

triangulare) 

REFERENCES

APPENDIX: SENSORY EVALUATON QUESTIONNAIRE

Vegetables are rich sources of vital ingredients in healthy and balanced human and animal diets (Osuagwu, 2008). They are fresh and edible portions of an herbaceous plant. Green leafy vegetables form an indispensable constituent of diet in Africa generally and West Africa in particular. Generally they are consumed as cooked compliments to the major staples like cassava, cocoyam, guinea corn, maize, millet, rice and plantain (Oguntona, 1998). They contain valuable food ingredients which can be successfully utilized to build up and repair the body. They are important low cost foods containing low levels of fat and high level of vitamins, minerals, fiber, some calorie and protein (Mepba et al., 2007). Vegetables are also good sources of carotene, ascorbic acid, riboflavin, folic acid and minerals like calcium, iron and phosphorus which have several health benefits including therapeutic uses such as treatment of scurvy, prevention of cold, correction of hypertysosinomenia, malformation of bones and anaemia in new born infants (Fasuyi, 2006). As a result of these, they are preciously valued and are also preserved for their economic importance in the advanced countries of the world.

Vegetables also contain phytochemicals which are nutritionally and medicinally useful but atimes reduce the bioavailability of nutrients in human system (Fasuyi, 2006). Vegetables contribute to the Recommended Dietary Allowance (RDA) of nutrients and also contain toxins and antinutrients such as oxalic acid and others. Depending on the concentration, these antinutrient compounds may reduce the edibility, nutritional value and health benefits of vegetable. Cooking or other processing methods may be necessary to eliminate or reduce these antinutrients (Alvarez, 2002). 

Vegetables are eaten raw or processed. Any method selected for processing vegetables should be such that does not adversely affect the colour, texture, flavour and nutritional values especially the vitamins and minerals (Edeoga et al., 2006). Fasuyi (2006) reported that consumption of vegetables helps towards controlling blood pressure and cholesterol level, prevent some types of cancer, avoid painful intestinal ailment called diverticulosis and guard against cataract and muscular degeneration which are two common causes of vision loss.

Waterleaf (Talinum triangulare) is an herbaceous perennial, caulescent and glabrous plant widely grown in the tropical region as a leaf vegetable (Ezekwe et al., 2001). It is consumed as a vegetable and constituent of a sauce in Nigeria. Nutritionally, waterleaf has been shown to possess essential nutrients like B- carotene, minerals (such as calcium, potassium and magnesium), protein, pectin and vitamins (Ezekwe et al., 2001). Waterleaf (Talinum triangulare) is a common edible leafy vegetable, belonging to the family of portulacaceae. Different ethnic tribes in Nigeria refer to it as follows: Edos- Adodoro, Efik- Mmong ikong, Igbo- Nti oke or Ofebekee, Tiv-Ashwe, Yoruba-Gbure and Yagbaland in Kogi State- Adegbere. Like other vegetables, it contains carotenoids such as lutein and zeaxanthin which act as stimulants and in a way influencing the immune cells of the eyes (Winston, 2007). Disu (2010) reported that waterleaf is eaten cooked as a pet-herb and in soups, as a condiment in sauces or raw in salad, besides being very rich in mineral salts and amino acids as well as having anti-scorbutic properties i.e. prevention against scurvy. Oguntona (1998) reported that consumption of waterleaf has risen to about 360g per day in the recent time. He indicated that one of the wonderful components of vegetables is the indigestible fiber which sops up water like a sponge and expands when it passes through the digestive system. This calms the irritable bowel by triggering regular bowel movements, decreasing pressure inside the intestinal tract and may help prevent diverticulosis (the development of tiny, easily irritated pouches inside the colon). Considering the potential benefits of the nutrients contained in waterleaf, there is need for intensive investigation into their sensitivity to the methods of processing them (Aja et al., 2010).

Micronutrient deficiency is still a public health problem in Nigeria despite the effort that has been made to eliminate it. World Health Organization (WHO) (2000) reported that about 30% of the population in developing countries suffer from one or more of the multiple forms of nutritional deficiencies, especially that of micronutrient.  Some vegetables are not available during dry season which makes them scarce and expensive to purchase. But during rainy season, despite the abundance of these vegetables, there is still the problem of micronutrient deficiency in Nigeria. Schippers (2000) observed that deficiency diseases were caused partly because of the food gap seasonality in which people experience food abundance, especially vegetables during the rainy season and severe scarcity during dry season. 

Waterleaf (Talinum triangulare) is indigenous to West Africa especially the eastern part of Nigeria (Oguntona, 1998). It is heavily consumed by people of Akwa Ibom and Efik’s.  Waterleaf (Talinum triangulare) is a highly perishable vegetable. It needs special processing methods to prevent decomposition. These processing methods either change the nature and constituents of vegetables positively or negatively (Tesleem et al., 2008). In order to recommend this vegetable that is widely consumed by the Ibibio’s and Efik’s to other tribes, it becomes necessary to investigate the effect of different treatment on the chemical content and acceptability of blanched, squeeze-washed, sun dried and oven dried waterleaf (which helps to retain essential nutrients in the vegetable when subjected to a temperature of 550C - 600C).

The main objective of this study is to determine the effects of different treatments on the chemical content and acceptability of waterleaf (Talinum triangulare). 

The specific objectives include to:

The benefit of green leafy vegetables cannot be overemphasized; they form excellent supplements for poor cereal diet and serve as a source of fiber in diets (Okaka et al., 2002). A diet rich in vegetables may protect against diseases (Lampe, 1998). Considering the potential benefits of the nutrients contained in waterleaf, there is need for intensive investigation into their sensitivity to the methods of processing them. The results of this work will provide data on the chemical content and acceptability of waterleaf using blanching, squeeze-washing, sun drying and oven drying method. It will enlighten the consumers on the use of this vegetable and will also encourage widespread consumption of waterleaf vegetable by non indigenes. Dietitians, nutritionist and other health workers conducting nutrient intake of vegetable in communities will utilize the information in calculating nutrient intake of individuals. Dietitians can also use this information in the hospital during dietary counselling to patients with various disease conditions. Nutritionists can use this information to educate or enlighten people on the nutritional benefits of water leaf vegetable so as to reduce micronutrient deficiencies.

Other health workers can also use this information to enlighten people on the effect of waterleaf vegetable in the body and how they can be processed to ensure that vital nutrients in them are not destroyed.

The information from the chemical content of waterleaf can form part of food composition table which can be used by other researchers. It will also contribute to the knowledge which will form part of literature for further use.