Effect of clarification on the polyphenolic compound content and antioxidant activity of commercial apple juices

Apples are a rich source of polyphenolic compounds and significantly contribute to the antioxidants in the human diet. However, apples are not just consumed fresh; approximately one third of apples produced are processed into numerous products, apple juice being the most popular. Clarification, one of the processes involved in apple juice production, removes pectin substances and fibres, resulting in clear juice. However, some juices are not clarified and are sold as cloudy apple juice. The aim of this study was to determine the effect of clarification on the polyphenolic compound content and antioxidant activity of commercial apple juices. The aim was accomplished by analysing 6 cloudy and 11 clarified apple juices. High performance liquid chromatography (HPLC) and the Oxygen Radical Absorbance Capacity (ORAC) assay were used to measure the content of polyphenolic compounds and the antioxidant activity, respectively. The results generated from the analyses indicated that the total polyphenolic compounds were 2.8 times higher in the cloudy than in the clarified apple juices (p = 0.049). Similarly, the cloudy apple juices possessed significantly more (2.5 times) antioxidant activity (p = 0.036) compared to the clarified apple juices. Therefore, it was concluded that the clarification process decreases the polyphenolic compound content and the antioxidant activity of commercial apple juices.