Stabilization of L-(+)-Ascorbic Acid in an Iron Fortified Vegetable Product (Cucurbita Moschata Duchesne Ex Poiret) Using an Alginate Coating

Abstract

In previous studies it was observed that in fortified pumpkins(Cucurbita moschata Duchesne ex Poiret) with iron (Fe) and L-(+)-ascorbic acid (AA), the latter had a minimum retention because AAstabilization was adversely affected by the presence of Fe. From this, itwas proposed compartmentalize these two nutrients, being Fe applied tothe impregnation of mesocarp pumpkin, while the AA was dissolved in acoating formulation consisting of alginate. Pumpkins, cut and blanched,were subjected to a dry impregnation. Two batches were prepared, one inwhich the Fe and AA were incorporated into pumpkin tissue, while in thesecond batch the vegetable matrix was only fortified with Fe. The studiedsystems were: a) Control fortified pumpkins with Fe and AA, coveredwith alginate coating (C); b) fortified with Fe, covered with alginatecoating containing AA (F). In addition, two water activity (aW) conditions0.920 (F1 and C1) and 0.760 (F2 and C2) were tested. All systems werecontained in plastic trays, packaged in plastic bags and stored at aconstant temperature of 25ºC for 23 days. During storage, AAconcentration as well as color changes were registered. The AA loss andalso b* and Chroma (Chr) parameter reductions fitted to a first orderkinetic. For aW 0.760, the values obtained for the AA initial content weresignificantly (p < 0.05) higher, while the rate constants of AA loss werelower. The kinetic constants for color parameters were one order lowerthan AA loss. In general, F systems showed a faster reduction of b* andChr than controls (C), but the aw assayed did not affect the rate of colorchanges. When fortified pumpkins were tested at aw 0.92 and storage at18 and 25ºC, it was observed reduction of AA loss rate only in F1pumpkin at the lower temperature. The reduction of color parametersshowed an important influence of both compartmentalization of AA andstorage temperature. It could be concluded that AA supporting on analginate edible coatings enhances this vitamin retention and then it couldbe represent an effective strategy when developing food products fortifiedwith iron.