In the present study, phenolic extracts and fractions from Canadian rowanberry (Sorbus aucuparia) and crabapple (Malus baccata) were screened for antioxidant activity using DPPH radical scavenging activity, and β-carotene bleaching assays. Furthermore, rapeseed oil was supplemented with extracts/fractions and performance was assessed during accelerated storage at 65°C, under Rancimat at 120°C, and during frying at 180°C. A number of phenolic fractions showed significantly higher radical scavenging and antioxidant activity in the oil than the synthetic antioxidant, butylated hydroxytoluene (BHT). At the end of the 7-day storage, the peroxide value was reduced by up to 42% in the presence of extracts. The extent of thermooxidative degradation was significantly lower in oils fortified with the fruit extracts, with fractions from Sorbus species being more effective. Results from the present study suggested that polyphenolic extracts from these fruits can offer effective alternative to synthetic antioxidants during frying and storage of vegetable oils.