Thursday, August 17

Carotene pigments in mango and carrot

Mangoes and carrots are beautiful to look at because they contain rich deposits of carotene pigments. The carotenes come in many different variations, and range in color from yellow to deep orange. Beta carotene in particular is a valuable nutrient because it's an antioxidant, and because our bodies can convert it into vitamin A, which has important roles in our eyes and in other tissues. So we can count on orange-colored fruits and vegetables to be especially good for us. But often we don't get as much of their goodness as we might think.
Carotenes are much more soluble in fats and oils than in water. The cells of plants are mostly water, so the cells have to package the carotenes in special structures. One common structure is a solid crystalline mass. This is what carrot cells contain, and as a result, raw carrots give up a relatively small proportion of their carotenes. When we eat a raw carrot, the crystals only partly dissolve in the water-based mass of carrot, and only some of the carotene molecules are free for our intestinal cells to absorb. Cooked carrots are much more nutritious. The heating process disrupts the cells and carotene crystals, mixes the carotene molecules with other fatty materials in the carrot tissue and the rest of our meal, and makes them more readily available for absorption.
Mangoes are a different story. Reinhold Carle and colleagues at Hohenheim University recently studied mango cells and found that they store their carotene pigments not in solid crystals, but in microscopic oil droplets, where they are predissolved and so presumably much more available for our bodies to absorb them, even when we eat the fruit raw.
In a 2003 paper, Carle and colleagues reported that dried mangos are a concentrated source of beta carotene, even though the drying process does destroy some of the pigment. Sun-dried fruit suffer the greatest losses.

Vasquez-Caicedo, A.L. et al., J. Agric. Food Chem. 2006, 54 (16) 5769.