<i>In vitro</i> acid-base buffering capacity of some Nigerian green leafy vegetables and fruit juices

Abstract

Background: Nigerian diets are mostly composed of starchy staples which is usually eaten with vegetable soup or stew. The preponderance of a food type may modify the body buffering capacity and interfere with the development of diseases. Objective: This study was carried out to evaluate the in vitro buffering capacity of some Nigerian green leafy vegetables (GLV) and fruits. Methods: Ten distinct types of green leafy vegetables (GLV) namely: bitterleaf, curry leaf, ewedu leaf, Amaranthus hybridus (locally called green) pumpkin leaf, scent leaf, soko leaf utazi leaf, uziza leaf, water leaf, were oven dried. While fruits like apple, carrot, garden egg, lemon, lime, mango, orange, pineapple, soursop, water melon, were juiced. The dried GLV were homogenised in deionised water and filtered to obtain an extract. The pH of the extract and fruit juices were determined. The in vitro buffering capacities were determined by titrating the extract with initial pH greater than 4 with 1M HCl until pH decreased to 2. Extract with pH lower than 4 was titrated with 1M NaOH until the pH increased to 4. Results: GLV had a high buffering capacity (BC) from (2.03 ± 0.10 to 6.45 ± 0.19). Green (Amaranthus hybridus) had the highest BC while uziza leaf (Piper guineense) had the lowest. The fruits had BC from minus 7.52 ±0.07 to 4.56 ±1.76). Oranges (Citrus sinensis) and pineapples (Annas comosus) had the highest BC. Lemon had the lowest BC of -7.52. other fruits with negative BC were lime; (-5.95 ±2.62) and soursop (-4.57 ± 1.75). Conclusion: Oranges, pineapples, green and water leaf had high buffering capacities. Lemon, lime and soursop had negative buffering capacities. These fruits and GLV can be used as adjuvant for nutrition interventions with the aim of alkalinizing diets for therapeutic purpose against disease and cancer progression.

Keywords: Buffering capacity, pH, fruits, vegetables