Pumpkin (Cucurbita maxima) by‐products: Obtaining seed oil enriched with active compounds from the peel by ultrasonic‐assisted extraction

Abstract

Ultrasonic-assisted extraction (UAE) of the oil from the seeds/peel mixture of pumpkin using ethanol as solvent was investigated. The effects of the ultrasound, solvent volume, time, and temperature on the oil yield were evaluated. Oil extraction from the seeds by ultrasound and the mixture by Soxhlet extraction (SE) was also performed. The use of ultrasound and higher availability of ethanol (up to 6 mL g −1 sample) favored the oil removal. In the extraction kinetics, the washing step was verified in the first 20 min, corresponding to 79-89% of the total oil yield. The diffusion coefficient increased from 30 to 75 C, as well as the spontaneity of the extraction, achieving 71% of the SE. Linoleic and oleic acids were found in higher concentrations in the oils. UAE made possible the greater extraction of β-carotene, tocopherols, and fistosterois, and the peel addition provided higher contents of these compounds.

Simultaneous extraction of the oil from the kernel and pulp of macauba fruit using a green solvent

“…According to Gayas, Kaur, and Gul (2017) the extraction carried out at elevated temperatures causes softening of the plant tissues, promoting the removal of oil bound inside the matrix by the solvent used in the extraction process. This softening may be mainly related to an increase in the oil diffusion coefficient (Ramandi, Ghassempour, Najafi, & Ghasemi, 2017), which improves the oil diffusivity and solubility in the extraction solvent (Ramandi et al., 2017; Shirsath et al., 2017; Zhang et al., 2009), leading to a greater mass transfer (Massa et al., 2019; Ramandi et al., 2017; Zhang et al., 2009).…”

“…This can be explained by the fact that β-carotene is susceptible to high temperatures over long periods of time, and thus, its degradation may have occurred in the conventional extraction (Castejón, Luna, & Señoráns, 2018). Cuco et al (2019), Massa et al (2019), and Rodrigues et al (2017) also reported higher β-carotene extraction in UAE compared to conventional extraction.…”

“…Obtaining the oil from these two parts of the macauba fruit simultaneously, in only one extraction step, would provide oil with the beneficial characteristics of the kernel, such as thermal stability due to the fatty acids composition, together with the β‐carotene and phytosterols from the pulp. This strategy has been previously adopted, with good results, for pumpkin by‐products (seed and peel) (Cuco, Cardozo‐Filho, & Da Silva, 2019; Massa, Stevanato, Cardozo‐Filho, & Da Silva, 2019).…”

“…These effects facilitate solvent penetration into the plant matrix by promoting the extraction of oil and other compounds of interest due to the larger contact area between the solute and the solvent and improved transporting properties (Chemat, Zill‐e‐Huma, & Khan, 2011; Gogate & Kabadi, 2009; Sun, Liu, Chen, Ye, & Yu, 2011). Related studies on the UAE of pomace olive oil (Chanioti & Tzia, 2017), hempseed (Rezvankhah, Emam‐Djomeh, Safari, Askari, & Salami, 2018), radish seed (Stevanato & Silva, 2019), Moringa peregrine (Mohammadpour, Sadrameli, Eslami, & Asoodeh, 2019), and mixture of pumpkin seeds/peel (Massa et al., 2019) demonstrated the efficiency of the technique compared to the conventional method in terms of oil yield and quality.…”

“…Gayas et al (2017) observed the increase in oil yield of the apricot almond from 42% to 46% when the temperature was raised from 45 to 60°C in the ultrasonic bath Massa et al (2019). investigated the UAE of oil from seed/peel pumpkin at a temperature range of 30 to 75°C, using ethanol as a solvent.…”