Anatomical traits of pumpkin (Cucurbita moschata Duch) as evaluation parameters of bioaccessibility of carotenoids

Abstract

Pumpkin (Cucurbita moschata Duch.) has high potential as source of carotenoids with provitamin A activity, especially all-trans-ß-carotene, and are widely consumed by the Brazilian population. Consumption may be useful in preventing the vitamin A deficiency, which corresponds to a public health concern in Brazil. The cooking style can affect the carotenoids retention, induce the isomerization cis-trans of the ß-carotene, bioaccessibility and bioavailability. The aim of this study was to evaluate the bioaccessibility of carotenoids in biofortified pumpkins submitted to different cooking styles through microscopic techniques. Five biofortified pumpkin genotypes were submitted to three cooking methods (boiled in water, steam and microwave oven). The anatomical analyses revealed some differences regarding the integrity and morphological traits of parenchyma cells from mesocarp, related to the type and time of cooking. In natura samples revealed intact fragments with round shaped cells connected to each other, the middle lamella preservation and, carotenoids preserved in the plastids. The cooking preparation with boiling water harmed most of middle lamella, resulting in small fragments and abundant isolated mesocarp parenchyma cells. These cells had variable shapes, round but most exhibiting flatten and collapsed cells, but still intact with preserved cell walls. Broken cells were rare. Carotenoids were abundant within the cells. The microwave oven cooking showed that mesocarp parenchyma cells remain mostly preserved, with most cells still connected to each other, which indicates the integrity of middle lamella. The cells showed rounded shape, and carotenoids were abundant and preserved within cells. Preparations with water vapor for 5 minutes exhibited sparse isolated cells and small fragments with cells still connected to each other. Most isolated cells showed rounded and flattened shapes, mostly collapsed but still preserved cell walls. Carotenoids were abundantly preserved within mesocarp parenchyma cells. Those cells which retained the integrity of middle lamella were still bonded to each other. They remained mostly rounded shaped, and carotenoids were within cells. Thus, cell walls and chromoplasts act as barriers that retain carotenoids encapsulated avoiding their cell release and absorption during digestion, compromising their bioaccessibility. This article is an output of the HarvestPlus programme