Blueberry-added black tea: Effects of infusion temperature, drying method, fruit concentration on the iron-polyphenol complex formation, polyphenols profile, antioxidant activity, and sensory properties

Abstract

Herein, a food-to-food fortification with blueberries and black tea was performed for people suffering from iron deficiency, creating a new functional product with high consumer acceptance. Black tea was mixed with varying concentrations of sun-dried or freeze-dried blueberries and infused at different temperatures. Spectrophotometric analysis revealed that the addition of blueberries to black tea inhibited the formation of the iron-polyphenol complex by up to 97 % (p <.001). Using β-carotene bleaching and 2,2-diphenyl-1-picrylhydrazyl assays, 50 % freeze-dried blueberry and 50 % black tea (FDFBT₅₀) was determined to be the sample with the highest antioxidant activity (p <.001).The polyphenol profiles were investigated by high-performance liquid chromatography. Principal component analysis (PCA) was performed to categorize the tea samples. The findings demonstrated that the FDFBT₅₀ sample was the best candidate among the samples, considering both the consumer acceptance and the bioactive parameters that showed statistically significant differences.

Keywords: Antioxidant activity; Black tea; Blueberry; Iron-polyphenol complex formation; Phenolic profiles; Principal component analysis.