Comparative analysis of the nutritional composition of pulp and peel of prickly pear

Abstract

Introduction: Nowadays, there are two major concerns of society, namely: (i) concern for health and demand for foods that may have health benefits; and (ii) increase of food waste produced by the food industry. The study of food and its by-products features can be one of the solutions for these two major concerns. Aim: In this study a comparative analysis was performed between the pulp and the by-product of prickly pear determining moisture, ash, total protein, total fat and dietary fibre contents. Methods: In 2017, the prickly pears were obtained at Herdade de Peliteiros (Silveiras, Montemor-o-Novo, Évora). For determination of moisture content, a gravimetric method was used applying a dry air oven, and the ash content was determined using the process of incineration at 525 °C. For total protein content, Kjeldahl method was applied, and for total fat, acid hydrolysis followed by extraction with petroleum ether using a Soxhlet apparatus. Finally, the dietary fibre content was determined by an enzymatic-gravimetric method. Results: With the results obtained, it was possible to verify that water is the main constituent of the pulp and peel of prickly pear, 83% and 84%, respectively. It was also found that the pulp had a higher content of total protein, total fat and dietary fibre than the by-product of prickly pear. However, the peel also shows considerable amounts of dietary fibre (2,8 g/100 g). Conclusions: In summary, both parts of prickly pear can be considered a good source of dietary fibre. This study may also contribute to promote the use of prickly pear by-product in the formulation of new food products and therefore to reduce food waste.