Physicochemical characterization of epicuticular coating of apples sold in Abuja Nigeria

Abstract

Most of the apples consumed across Nigeria are imported from South Africa, Europe and United States of America. Despite the epicuticular hydrophobic wax naturally produced by the fruit which makes it resistant to external spoilage factors, extra coating is usually employed by producers for protection against biotic and abiotic attack during storage in order to extend shelf-life. Nowadays, Nigerians have raised concerns on the nature, level and safety of these wax coatings in apples available in Nigerian market. The results of organoleptic, physicochemical and Fourier transfer infrared spectroscopy (FTIR) analyses suggested that the epicuticular waxes of apples in Abuja markets are mainly from petrochemical sources with adulterants from waxes of vegetable sources or beeswax. The mineral concentration of Cu, K, Mg, Mn, Zn and Pb in waxes per average sized apples (mg/g) ranged from 1.73 to 15.66, 10.80 to 1357, 26.46 to 173.12, 0.11 to 0.22, 2.05 to 41.80 and 3.78 to 11.66 mg/g, respectively. The results indicated hundred (100%) of the samples contained copper (0.02 mg/g) and zinc (0.05 mg/g), and sixty percent (60%) contained lead above WHO permissible limit (0.01 mg/g). It is however recommended that the layer of coating should be to reduce apple growers or sellers to the barest minimum to avoid over-coating and the amount of waxes consumed per apple. Waxes can be removed from apple by dipping the apple in hot water for a few seconds to remove the wax or washing with pure white vinegar and rinsing in warm water. Key words: Apples, waxes, beeswax, paraffin wax, mineral, Fourier transfer infrared spectroscopy (FTIR).