Applying Different Sample Treatment Strategies for Evaluating Phosphorus Distribution in Orange Juice

Abstract

Assessment of phosphorus in fruit juices is of great interest due to its essentiality and nutritional properties. This study applied sample treatment strategies to determine phosphorus in fractions of juices. Firstly, total phosphorus (P total ) was determined from digestion and sample suspension exploring direct analysis by inductively coupled plasma optical emission spectrometry, which presented no significant difference, for 95% of confidence level. Then, free phosphorus (P free ) was determined by spectrophotometry and represented 30-90% of P total with an inverse relationship respecting P total concentration. Fractioning according to particle size evidenced highest fraction of P free in samples after filtration. Fractioning of phosphorus based on its charge was also performed and the high percentages of P in the anionic fraction (from 91.2 to 95.9%) are related to free inorganic phosphate in equilibrium with its protonated forms. Thus, it is more assailable after consumption, giving this food great functionality on human diet.