Pumpkin waste: a valuable source of bioactives

Pumpkin, belonging to the Cucurbitaceae family, is one of the most common fruits cultivated in the tropical countries in the world and its consumption is associated with nutritional benefits as well as medicinal properties.1 For centuries, pumpkin pulp have represented an interesting source of nutrients and bioactives for humans, but in recent years, the reduction of agri-food waste production has received growing interest from policymakers, organisations, and researchers both at national and international levels.2 On this basis, peels, filaments, and seeds, but also pulp of pumpkins out of aesthetic standards of size, shape, and color can be used to obtain bioactive compounds, as for example carotenoids. These secondary metabolites show various healthy effects, including antioxidant, anti-obesity, anti-inflammatory, and anti-hypertensive.3 As a consequence, in the nutraceutical, cosmeceutical, and pharmaceutical fields, there is an increasing interest both in isolating these molecules and in characterizing vegetable extracts. An overview on the researches carried out recently on some Italian pumpkins will be. In a first study has been demonstrated that the encapsulation into solid lipid nanoparticles is a valid technological process guaranting the preservation of the antioxidant activity of β-carotene.4 More recently, an innovative extraction method exploiting ultrasounds and hexane:isopropanol (60:40, v/v) as extraction mixture was used to isolate carotenoids from pulp and waste (peels and filaments) of different pumpkin varieties. Spectrophotometric assays were applied to evaluate the total carotenoid content, and the antioxidant properties of extracts. Moreover, a liquid chromatography method was set up using a diode array detector to obtain a qualitative and quantitative analysis of carotenoidic fraction. A mass-spectrophotometry approach is key to identify the single molecules. The major carotenoids identified in pumpkins were β-carotene, together with lutein, antheraxanthin , mono- and di- esterified forms of some of these compounds. Taking into consideration that literature around carotenoids of pumpkin wastes is very lacking, the results of this research valorize them as excellent natural sources of antioxidants to apply in various industrial fields. Further researches are currently underway to study different pumpkin species (C. maxima vs C. moschata), to evaluate different years (20201-2022) of harvesting, and to optimize the encapsulation of a carotenoid-rich extract, obtained from pumpkin pulp and waste.