Effect of soaking, boiling and frying on selenium content of major african fresh foods

Abstract

Selenium is an essential trace element that is crucial for normal functioning of human body systemsand it is obtained from diet or dietary supplements. The concentration of selenium (Se) varies fromsoil-to-soil and therefore in various food types. We profiled the selenium concentration in the majorAfrican fresh foods and studied the effect of boiling, frying and overnight soaking on their seleniumcontent. The foods were taken to the chemistry laboratory, processed for determining seleniumconcentration in the fresh foods and then subjected to the various treatments before determiningtheir Se concentration using an atomic absorption spectrometer. Among the fresh foods studied,pumpkin seeds were found to have the highest Se concentration (109.25 ± 0.125 parts per billion(ppb)), while Irish potatoes had the lowest (16.25 ± 0.125 ppb). In most fresh foods studied, boilingand frying had the effect of reducing the Se concentration, except in yams that showed an increasedconcentration after frying. Overnight soaking of matooke (plantain bananas) and beans showed aneffect of causing a considerable reduction in the Se concentration from 36.375 ± 0.281 ppb and59.125 ± 0.031 ppb to 14.03 ± 0.441 ppb and 24.375 ± 0.281 ppb, respectively. Boiling and fryingcause a significant reduction in Se concentration of most African fresh foods. Overnight soaking ofmatooke and beans caused further reduction in the selenium concentration of the fresh foods. Thisimplies that people who pre-soak their food before cooking it are likely to lose more selenium thanthose who do not soak and may be more likely to suffer from Se deficiencies.