Ultrasound-assisted extraction of essential and toxic elements from pepper in different ripening stages using Box–Behnken design

Abstract

The influence of extraction parameters on the ultrasonically assisted extraction (UAE) of K, Na, Ca, Mg, Zn, Cu, Fe, Mn, Cr, Se, Mo, Li, Al, B, Pb, Hg, Cd, As, and Ni was studied to determine the conditions when a minimum of essential and maximum of toxic elements is leached from peppers, depending on its ripening stage. The effect of process variables was investigated by using Box–Behnken design. Each essential element had a different optimal condition for minimal leaching, while the toxic elements were predominantly extracted with acetic acid solution as extractant. The highest correlation between extraction conditions and concentration of extracted elements was found for aqueous extracts of mature green pepper. The concentration of acetic acid highly influenced the leaching of elements and a strong correlation between the concentration of Al, B, Fe, and Mn, and the UAE experimental conditions were observed. Practical applications: This study investigates the leaching of minerals and heavy metals present in vegetables to the most commonly used media (water and acetic acid) during processing and canning. The data from this study may be useful for improving the quality of processed pepper products due to new information on how different parameters influence these losses (ripening stage of peppers, medium/solvent used for preparation, or storage, applied temperatures, time, mass to volume ratio). Essential elements are better preserved during the processing of intermediate breaker and mature red pepper compared to green mature fruits. Better retention of essential elements in the breaker and mature red pepper (that are mostly used in industrial processing) can be achieved by reducing the contact time with water, as well as mass to volume ratio. Leaching of toxic elements Al, Hg, and As can be improved with an acetic acid solution.