Effect of Processing Methods on the Chemical Composition, Hypoglycemic and Hypolipidemic Potentials of Vernonia Amygdalina (Onugbu) and Gongronema Latifolium (Utazi )Vegetables.
ABSTRACT
Vernonia amygdalina (VA) and Gongronema latifolium (GL) vegetables were processed using four methods; boiling for 5, 10, 15, 20, 25, 30 min, boiling for 5min each in a palm oil and salt (NaCl) medium, moist heating at 40 oC, 60 oC, 80 oC and 100 oC for 5 min, drying under the heat of the sun (35 oC – 40 oC), solar (45 oC – 50 oC ) and oven (50 oC – 55 oC) and de-bittered by boiling and squeeze-washing.
Effects of these processing methods on the chemical composition, hypoglycemic and hypolipidemic potentials of the vegetables were evaluated. In vitro antioxidant potentials of processed and unprocessed vegetables were estimated using the 1,1-Diphenyl-2-picryl hydrazyl radical (DPPH) while superoxide dismutase and glutathione peroxidase were used for in vivo model.
The hypoglycemic properties of aqueous extracts of VA and GL were evaluated in rats using a dosage of 300g/Kg bodyweight. The effect of the vegetable extracts on rat’s lipid peroxidation and liver function tests were studied. Boiling process reduced (p<0.05) all the nutrients excluding crude fat, carbohydrate and mineral contents. Phytochemical content of both vegetables was similar.
However unprocessed VA had higher (p<0.05) alkaloid (1.73g/100g), tannin (0.23g/100g), saponin (8.02 g/100g) and phytate (1.46g/100g) values than unprocessed GL but flavonoids and anthocyanin were significantly (p<0.05) higher in GL. Boiling in a medium containing palm oil and salt (NaCl) reduced the saponin content of both vegetables suggesting that oil and salt form complex compounds with Saponin reducing its concentration.
INTRODUCTION
In recent times consumers have begun to look at food not only for basic nutrition but also for health benefits. This interest combined with a widespread understanding of how diet affects disease, rising health-care costs and an aging population are driving a growing and attractive market for functional/ nutraceutical foods and natural health products.
Nutraceutical, a term that combines the words “nutrition” and “pharmaceutical”, is a food or food product that provides health and medical benefits including the prevention and treatment of chronic diseases, improving health, delaying the aging process and increasing life expectancy (American Dietetic Association,1995; Hasler, 2000; American Nutraceutical Association ANA, 2011).
Many researchers have suggested that food can be effectively used as medicine to prevent and treat diseases. This agrees with the words of Hippocrate “let food be thy medicine” (Wildman, 2001). Sequel to this, scientists in late 20th century began to identify physiologically active components in foods from both plants and animals that had the potential to reduce risk of a variety of chronic diseases (Wikipedia, 2011).
This knowledge of interaction between diet and development of disease based on an individual’s genetic profile has led to technological breakthrough which could eventually make it feasible to tailor a diet to an individual’s specific genetic profile. This will have profound effect on future disease prevention efforts with right diet. Food choices can affect health since some foods provide specific health benefits.
These factors have coalesced into the demand for special foods known as “functional foods and nutraceuticals” (Wardlaw and Hampl, 2010). Most of these food sources come from plants which is an indicator of environmental health due to the presence of bioactive compounds. Green leafy vegetables (GLV) are the most important nutritional part of plant with the presence of many vitamins and minerals.
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