Laboratory Analysis of pH and Neutralizable Acidity of Commercial Citrus Fruits in Nigeria

This is an in vitro study to evaluate five different commercially available citrus fruits: viz., Sweet orange (Citrus sinences Osbeck), Grape [Citrus maxima (J. Buruan) Merrile], Lemon [Citrus limon (Burn F.) and Lime (Citrus aurantifolia Swingle. Evaluation of their pHs and neutralizable acidity were made. A 50 mL of each fruit was prepared by juice press. Initial pH was measured in triplicate for the five fruits. The neutralizable acidity was assessed by measuring the volume of 0.10 N sodium hydroxide required to raise the pHs of each fruit to a neutral pH of 7.0. Results showed that all the evaluated drinks were acidic with pHs that ranged from 2.4 to 4.1. Lime produced the lowest mean pH of 2.4 and tangerine yielded the highest of 4.1. The mean volume of sodium hydroxide to neutralize the fruits ranged from 5.1mL to 104mL. Regarding neutralizable acidity, Lime required the highest NaOH to neutralize thus possessing the strongest potential to erode enamel. Tangerine required the least base to neutralize. All the 5 evaluated citrus fruits are acidic with pHs well below the critical pH (5.5) of enamel demineralization. Inappropriate consumption of these fruits especially lime may incite toothwear.