Antioxidant capacity and colour of strawberry jam as influenced by cultivar and storage conditions

Jam was prepared from five strawberry cultivars; 'Senga Sengana', 'Korona', 'Polka', 'Honeoye' and 'Inga'. The jam was stored at 4 and 20 °C, in darkness and under fluorescent light (950 lux). The quality parameters assessed were colour reflectance at 650 nm, Hunter L*,a*,b*, anthocyanin pigments and total antioxidant capacity assessed by FRAP-assay. Jam produced of all cultivars stored at 4 °C had significantly better colour qualities and FRAP-values than jam stored at 20 °C. The light conditions during storage did not affect the assessed quality parameters of the product during three months of storage. The cultivars 'Senga Sengana', 'Korona', 'Honeoye' and 'Polka' showed the highest a*-values (red colour), but only 'Korona', 'Honeoye' and 'Polka' showed a high total antioxidant capacity, as measured by FRAP and compared to 'Senga Sengana' and 'Inga'. Thus, to achieve a good coloured strawberry jam with high antioxidant capacity, the industry should consider to store the products at 4 °C and to replace 'Senga Sengana' with one of the 'Korona', 'Honeoye' and 'Polka' cultivars.