Caracterização das propriedades químicas e antioxidantes da semente, germinados, flores, polpa e folha desenvolvida de abóbora (Cucurbita pepo L.)

Abstract

The pumpkin comprises a total of 27 known species, having the scientific name Cucurbita spp., and belongs to the family of Cucurbitaceae. This vegetable fulfils the requirements of a healthy diet, being a fruit very appreciated by the consumers because of its smooth taste and nutritional value, mainly due to its high content of vitamin A. The seeds of pumpkin are also considered a good source of protein, fiber and oil, allowing their use in food enrichment, being currently consumed as snack. In addition, both male and female flowers are encountered on the same plant of the pumpkin, being edible. For many centuries the edible flowers have been making part of the human food, and there are currently studies that prove their antioxidant properties and nutritional factors. Nevertheless, little information on pumpkin flowers, as well as on sprouts, exists. In this sense, the present study intended to contribute to increase the knowledge on this subject, namely at the level of the chemical characterization and antioxidant properties of seeds, sprouts, flowers, fruit and developed leaves of pumpkin, in particular of Cucurbita pepo Linnaeus. In the first stage of the work the germination of pumpkin seeds was performed in laboratory (360 seeds were germinated, generating around 682 grams of sprouts which were subsequently used in the analysis. In parallel, for obtaining the other constituents, multiple seeds were planted in a greenhouse in a space of approximately 30 m². Concerning the chemical analysis performed, the moisture content of the seeds were much lower than of the other constituents analyzed, with approximately 5.79±0.01% when compared with percentages of around 90% of the other parts of the pumpkin. The seeds also showed to be a good source of oil (47.35±0.45 g/100g of fresh matter), fibers (30.78±1.34 g/100g of fresh matter) and total sugars (6032±213 mg of glucose/100g of fresh matter). The flowers presented the largest contents in ashes and proteins, with 12.87±0.66 and 8.76 ± 1.70 g/100g of dry matter, respectively. In relation to ascorbic acid, expressed in both fresh matter and dry matter, the flowers presented the best result, revealing that 100 grams of flowers (lyophilized) supply practically twice the daily dose required of ascorbic acid (45 mg/day) for a healthy adult. In relation to the concentration in total carotenoids, the developed leaves were the constituent that presented the highest value. Thus, the flowers and the developed leaves of the pumpkin appear as interesting sources of bioactive compounds. Regarding the analysis of the antioxidant activity, the roots and leaves of the sprouts were the constituents that had demonstrated the best results in all analyzes, although the flowers and the developed leaves also presented good results regarding the blocking effect of DPPH free radicals. The results obtained for the sprouts were surprising and leave a door open to subsequent studies, not only on pumpkin sprouts, but also on other vegetable varieties. In conclusion, the constituents of pumpkin have demonstrated a chemical and antioxidant compositions capable of conferring beneficial characteristics to human health.