Investigating the Antioxidant Capacity of Fruits and Fruit Byproducts through an Introductory Food Chemistry Experiment for High School

This paper reports a laboratorial internship included in the Portuguese Science and Technology promotion program “Internships for Young People in Laboratories (Ciência Viva no Laboratório)”, which provided high school students an opportunity to approach the reality of scientific and technological research in a higher education institution. During this internship, students acquired knowledge related to the assessment of the total antioxidant capacity (TAC) of fruits and their byproducts while learning techniques, such as molecular spectrophotometry, as an analytical methodology to measure TAC using the ferric reducing antioxidant power (FRAP) and the total phenolic content (TPC) assays. First, the students were introduced to solid–liquid extraction as a conventional technique to extract antioxidants from the selected matrices. In order to optimize the extraction yield, different solvents, temperatures, and extraction times were used. Then, the students developed skills on TPC and FRAP assays by performing calibration curves using standard antioxidants, namely, gallic acid and ascorbic acid, prior to the measurement of the TAC of fruits (apple and orange) and respective byproducts. Final analysis included TAC values for comparison between fruits and their byproducts and also the influence of the extraction conditions on the TAC levels. At the end, the students presented their findings in a scientific poster and in a postlaboratory quiz. This laboratorial internship has been carried out since 2012 and was designed to be performed during a week, 7 h per day, in groups of two young students.