Antioxidant capacity and colour stability of texture-improved canned strawberries as affected by the addition of rose (Rosa damascena Mill.) petal extracts

Antioxidant capacity of texture-improved canned strawberries (TICS) was studied during storage depending on the addition of polyphenol-enriched extracts from rose (Rosa damascena Mill.) petal by-product. Furthermore, the pigment retention and surface colour evolution were monitored by HPLC-DAD analyses and CIEL*a*b* measurements, respectively. The addition of rose petal extract (250-500 ppm) strongly contributes to the antioxidant capacity of the canned strawberries, resulting in 15-54% (Trolox equivalent antioxidant capacity, TEAC assay) and 21-40% (ferric reducing antioxidant power, FRAP assay) higher values as compared to the control sample, even after 12 weeks of storage. A significant pigment retention, i.e. 70-81% relative concentrations of pelargonidin 3-glucoside, was observed for the polyphenol-fortified strawberries during the fruit firming process and subsequent pasteurisation. Correspondingly, colour stability was improved since total colour difference (Delta E*) values were smaller than that of the control sample. The results obtained demonstrate an enhancement of antioxidant capacity by application of rose petal extracts to texture-improved strawberries, thus are shown promising for development of new functional foodstuffs. This polyphenol fortification is also suitable from a technological point of view, supporting colour stability during the enzymatic fruit firming process. (c) 2011 Elsevier Ltd. All rights reserved.