Effect of Pumpkin ( Cucurbita pepo ) Seeds Flour Enrichment and Cooking Process on Protein , In Vitro Protein Digestibility and Antinutritional Properties of Maize ( Zea mays L.) Flour Fritters ( Zitumbuwa )

Abstract

Protein-energy malnutrition (PEM) is one of the leading causes of death for under-five children in developing countries like Malawi. This is because these children consume more products made from whole maize flour, like fritters ( zitumbuwa ) , with poor protein content. Pumpkin seeds are locally available and contain high amounts of protein and amino acids like lysine. This makes pumpkin seed flour a good choice to improve the protein quality of fritters when combined with maize flour. This study aimed at evaluating the effect of pumpkin seed flour (0%, 15%, 30%, and 45%) and cooking method (baking and frying) on protein content, in vitro protein digestibility, and antinutritional content (phytate, tannins, and total phenolic) of the fritters. The pumpkin seed flour (PSF) and maize flour fritters were prepared by frying at 180˚C for 10 min while baking was at 150˚C for 2 h. Pumpkin seed flour significantly increased the protein content of the baked and fried fritters, ranging from 8.5% to 19.6% and 9.1% to 21.9%, respectively. Antinutritional content also increases as the level of pumpkin seed flour increases in fritters. The phytate, tannin, and total phenolic content of the raw maize and pumpkin seed flour ranged from 76.4 mg/100 g to 164 mg/100 g, 4.1 mg/100 g to 88 mg/100 g, and 31.9 mg/100 g to 69.4 mg/100 g, respectively. Cooking reduced antinutritional properties significantly (p < 0.05). Frying and baking significantly increased in vitro protein digestibility, which ranged from 80.7% to 90.4% and 82.9% to 93.1%, respectively. This study found that there was a weak, significant negative correlation between in vitro protein digestibility and antinutritional properties. The high protein content of the enriched fritters may indicate the potential of using locally available, underutilized pumpkin seed flour to serve as a protein supplement when developing different cereal food products, which in turn contribute to food security .