Physico-chemical, antioxidant and sensorial properties of fruit leathers made from "Malga" and "Murano" strawberry cultivars

Introduction. Strawberries are recognized as an antioxidant source due to their high content of anthocyanins, other phenolic compounds and ascorbic acid. The objective of this study was to formulate and to characterize fruit leather made from two strawberry cultivars using honey and lemon juice as ingredients. Materials and methods. The fresh fruits were pureed, mixed with honey and lemon juice and then dried in a dehydrator at 57 degrees C for 6 hours. Both fruit homogenates and leathers were characterized in terms of moisture content, total soluble solids content, titratable acidity, color by CIE L*a*b* system, total phenolic content by Folin-Ciocalteu method, total flavonoid content by the aluminium nitrate method, total anthocyanin content by the pH differential spectrophotometric method and antioxidant activity by the DPPH (2-diphenyl-1-picrylhydrazyl) procedure. A 9-point hedonic scale was used to evaluate strawberry leathers for color, sweetness, sourness, flavor, texture, and general acceptability. Results and discussion. There was a substantial increase in soluble solids content and titratable acidity of both strawberry leathers as a result of honey and lemon juice addition and drying. Fresh strawberry homogenates were lighter (higher L* values) as compared to fruit leathers. In addition, the color parameter a* showed a significant decrease in both cultivars after drying, that may be attributed to the oxidation of anthocyanins as well as thermal degradation. The total phenolic, flavonoid and anthocyanin content were higher both in the fresh homogenate and in the leather of "Malga" cultivar than in "Murano". However, DPPH antioxidant activity was slightly higher in "Murano" (35.21 mmol Trolox/100 g) than in "Malga" homogenates (34.45 mmol Trolox/100 g) but differences were not significant. After dehydration, the anthocyanin content in the strawberry leather decreased by 67.38% ("Murano") and 64.07% ("Malga"), while the total phenolic content decreased by 43.81% ("Murano") and 32.33% ("Malga"). In addition, after drying, reductions in the DPPH antioxidant activity of 40.5% ("Murano") and 38.5% ("Malga") were observed. In terms of sensory evaluation, "Murano" leather stand out as compared with "Malga", due to its more reddish color, stronger sweetness, lower sourness and more pleasant texture. Conclusions. Apart from their attractive appearance, taste and flavor, strawberry leathers are a good source of natural antioxidants including anthocyanins and other phenolic compounds.