Antioxidant Levels in Three Common Berries

Oxidative stress is thought to speed up aging and cause many types of diseases, including cancer, Alzheimer’s Disease, cardiovascular disease, eye disease, and Parkinson’s disease. Fortunately, many foods, including fruits, have high levels of antioxidants, which the body can use to counteract oxidative stress. The goal of this experiment was to compare the antioxidant power of three common types of berries that were fresh versus two weeks older. The hypotheses were: (1) that blueberries would have higher antioxidant levels than strawberries and blackberries, and (2) that older berries would have lower concentrations of antioxidants than fresh berries. Five samples of each type of fresh and old berries were homogenized and then the antioxidants were extracted with water and the samples were filtered. An assay was used to determine the Trolox equivalent units (TEU) in each sample. Data were analyzed with an analysis of variance test.  There were no significant differences in the antioxidant levels of the fresh strawberries (59 ±10.2 TEU/g), fresh blackberries (61.5 TEU/g), and fresh blueberries (49.8 ± 9.2 TEU/g; p>0.05). The antioxidant levels also did not decrease in old strawberries (52.9 ± 22.8 TEU/g) and old blackberries (62.1 ± 6.2 TEU/g). However, antioxidant levels were significantly lower in old blueberries (13.1 ± 6.6 TEU/g; p<0.05) compared to all other groups. In conclusion, fresh blueberries, blackberries, and strawberries are equally good sources of antioxidants, but blueberries rapidly lose this benefit after purchase.