Abstract
Natural pigments improve aesthetic value as well as antioxidant potential of a food product. This study was designed to determine the effects of green extraction techniques on carotenoids, polyphenols and antioxidant activities of pulp and peel of two varieties of pumpkin (Cucurbita maxima). Innovative green extractions (IGE; Ultrasound and Microwave-Assisted Extractions) synergised with corn oil (used as green solvent) were compared with conventional extraction (CE; hexane/isopropyl alcohol; 60:40, v/v). Results showed total carotenoids to be almost double on employing IGE (PM2-UAE-peel = 38.03 ± 4.21; PM4-UAE-peel = 33.78 ± 1.76 µg/g) when compared to conventional extraction (PM2-CE-peel = 19.21 ± 4.39; PM4-CE-peel = 16.21 ± 2.52 µg/g). Polyphenolic contents ranged between 510.69 ± 5.50 and 588.68 ± 7.26 mg GAE/100 g of extract in IGE, compared with conventional extracts (269.50 ± 2.17 to 318.46 ± 6.60 mg GAE/100 g) and percent inhibition of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) ranging between 88.32 ± 1.51 and 93.53 ± 0.30% in IGE when compared with conventional extraction (50.61 ± 1.44 to 57.79 ± 2.09%). Further, oxidative stability of carotenoids extracts from IGE (protection factor = 1.59 ± 0.01 to 1.81 ± 0.05) were found to be significantly higher (p < 0.05) than conventional extracts. Based on results, this study supports the use of innovative green extraction techniques to obtain bioactive pigments like carotenoids. It is anticipated that results generated will find potential applications in food, pharmaceutical and cosmetic industries.
Highlights
There has been a huge global demand for natural plant-derived pigments, which are enriched with antioxidant potentiality and can replace artificial pigments, especially in the food, pharmaceutical and cosmeceutical-based industries
Combining the innovative technologies (UAE and microwave-assisted extraction (MAE)) with green solvent extraction to extract carotenoids from pumpkin peels and pulp could prove to be advantageous in terms of improving the extraction efficiency, reducing the extraction cost, time, energy and enhancing the yield of the target compound
Corn oil is a well-recognised “green” alternative for petroleum-based or organic solvents and this can be safely used as an reliable extraction medium
Summary
There has been a huge global demand for natural plant-derived pigments, which are enriched with antioxidant potentiality and can replace artificial pigments, especially in the food, pharmaceutical and cosmeceutical-based industries. Fruit and vegetable wastes and by-products obtained from food-processing industries are consists of seeds, peels and pomace Efficient utilisation of these can bring a lot more opportunities for the extraction of several bioactive compounds including basic ingredients like polysaccharides, proteins and peptides, dietary fibres, etc., and other plant secondary metabolites such as pigments, polyphenols, antioxidants, antimicrobials, etc. [5,6], which have possible applications in food, pharma and nutraceutical industries Among these are the natural pigments that can find potential applications as they are natural (plantorigin), safe (non-toxic), potent antioxidants, as well as can enhance the aesthetic appeal of the processed food commodities. Carotenoids, one of the major pigments, are copiously present in the food industrial wastes, and can be explored as natural colourants in food, pharma and cosmetic applications [3,7]
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