Flavonoids in Brazilian Fruits and Vegetables and Their Processed Products

The flavonols and flavones of Brazilian fruits and vegetables were determined using a high performance liquid chromatographic (HPLC) method which was previously optimized using central composite rotational design and surface response analysis, and validated. Quercetin was encountered in all of the fruit samples analyzed, the highest concentration being in apple 'Fuji'. Myricetin was found in cashew-apple, pitanga, and their products, with pitanga having the highest level. Kaempferol was present in strawberry, acerola, pitanga, and their products, with the highest concentration in acerola. The processed products generally had lower flavonoid content compared to the unprocessed pulp, indicating losses during processing. Quercetin was also the most widely distributed flavonol in the vegetables analyzed, onions, kale, and rucula being the richest sources. Rucula contained the highest levels of kaempferol. Apigenin was found only in parsley and at high concentration. The flavonoid contents tended to be higher in the summer, but the difference was statistically significant only for quercetin in curly lettuce and kale. Dehydrated onion had widely varying quercetin content, indicating lack of quality control in the processing plants. Dehydrated parsley, on the other hand, did not have significant difference in the apigenin contents among four brands analyzed. The behavior of flavonols in minimally processed kale, New Zealand spinach, and rucula during passive modified atmosphere storage, under different conditions of temperature and light exposure, and covering the shelf life of these foods as determined by sensory evaluation was also investigated. The results showed that loss of quercetin and kaempferol was not a problem under the conditions studied, the levels even increasing at certain times during storage.