Unconventional Extraction of Total Non-Polar Carotenoids from Pumpkin Pulp and Their Nanoencapsulation

Abstract

Pumpkin is considered a functional food with beneficial effects on human health due to the presence of interesting bioactives. In this research, the impact of unconventional ultrasound-assisted extraction (UAE) and microwave-assisted extraction techniques on the recovery of total non-polar carotenoids from Cucurbita moschata pulp was investigated. A binary (hexane:isopropanol, 60:40 v/v) and a ternary (hexane:acetone:ethanol, 50:25:25 v/v/v) mixture were tested. The extracts were characterized for their antioxidant properties by in vitro assays, while the carotenoid profiling was determined by high-performance liquid chromatography coupled with a diode array detector. UAE with the binary mixture (30 min, 45 °C) was the most successful extracting technique, taking into consideration all analytical data and their correlations. In parallel, solid lipid nanoparticles (SLN) were optimized for the encapsulation of the extract, using β-carotene as a reference compound. SLN, loaded with up to 1% β-carotene, had dimensions (~350 nm) compatible with increased intestinal absorption. Additionally, the ABTS ((2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assay showed that the technological process did not change the antioxidant capacity of β-carotene. These SLN will be used to load an even higher percentage of the extract without affecting their dimensions due to its liquid nature and higher miscibility with the lipid with respect to the solid β-carotene.

Valorization of Pumpkin Byproducts: Antioxidant Activity and Carotenoid Characterization of Extracts from Peel and Filaments

“…The procedures for carotenoid extraction from the peel and filaments as well as the spectrophotometric determination of the TCC value of carotenoid extracts were carried out following the conditions optimized in a previous paper [12].…”

“…The TCC was determined by using a spectrophotometer (Lambda spectrophotometer, PerkinElmer, Inc., Waltham, MA, USA) set at 450 nm and dilutions (0.001-0.005 mg/mL) of the β-carotene standard. The TCC was expressed as µg β-carotene equivalents per gram of dry weight (µg β-CE/g DW) [12].…”

“…The ABTS procedure for the determination of the antioxidant properties of carotenoid extracts was carried out using a method developed in a previous work [12]. The antioxidant capacity was expressed as µg Trolox equivalents per gram of dry weight (µg TE/g DW).…”

“…The chromatographic separation was performed on a reverse-phase C-30 Develosil column (250 × 4.6 mm i.d., 5 µm, Nomura Co., Kyoto, Japan) using the following mobile phase solvents: A (MeOH: H 2 O, 97:3 v/v); B (MTBE). The optimized gradient program was reported in detail in a previous paper [12]. Excalibur software (Chromatographic Specialties Inc., Brockville, ON, Canada) was used for data acquisition.…”

“…In a recent paper, UAE was defined as the most performing unconventional extraction method used to isolate carotenoids from pumpkin pulp by using a binary mixture [12]. Based on this result, pumpkins of eight varieties were studied for their content of carotenoids, antioxidant activity, and carotenoid composition.…”