Cloud Point Extraction of Chlorophylls from Spinach Leaves Using Aqueous Solutions of Nonionic Surfactants

Abstract

Chlorophylls and their derivatives are currently used in a wide range of applications. To replace the volatile organic solvents commonly applied for their extraction from biomass, aqueous solutions of non-ionic surfactants are studied herein in the extraction of chlorophylls from spinach leaves. Aqueous solutions of several surfactants were screened, demonstrating that their hydrophilic-lipophilic balance (HLB) plays the pivotal role on the extraction performance, with the best results obtained for surfactants with a HLB ranging between 10 and 13. A response surface methodology (RSM) was then used to optimize operational conditions (surfactant concentration, solid-liquid ratio and temperature), leading to a maximum extraction yield of chlorophylls of 0.94 mg/g. After the extraction step, the chlorophylls-rich extract was concentrated by heating above the surfactant-water cloud point, leading to the separation into two-phases, and to a concentration factor of 9 and a recovery of 97% of chlorophylls in the surfactant-rich phase. The antioxidant activity of the extracts was finally appraised, showing that the antioxidant activity of the aqueous chlorophylls-rich extracts is higher than that obtained with volatile organic solvents. The obtained results show the potential of aqueous solutions of non-ionic surfactants to extract highly hydrophobic compounds from biomass and their possible direct use in cosmetic and nutraceutical applications, without requiring an additional recovery or purification step.

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“…For solid–liquid ratio of 1:100, the concentration of Chl a, Chl b and total Chl are 66.9 ± 0.1, 29.2 ± 0.1 and 96.1 ± 0.2 mg 100 g −1 , respectively. Leite et al . also verified the negative effect of solid–liquid ratio with decrease liquid (extractant) content in the extraction of Chls from spinach.…”

“…Chl b and total Chl presented an increase of 3.1‐ and 1.7‐fold in the concentration, while Chl a was not concentrated. Leite et al . also observed the partition of Chls from spinach to surfactant‐rich phase and consequently the concentration in this phase.…”

“…For spinach, an optimum temperature of 41°C was observed for Chls extraction using non-ionic surfactants. 53 The efficiency of solid-liquid ratio (1:10, 1:25, 1:50 and 1:100) on Chls extraction was observed using 5 wt% of Triton X at 50°C for 60 min (Fig. 2(d)).…”

“…The extraction ability of Chls improved with increasing temperature, reaching (Chl a = 66.9 ± 0.1 mg 100 g −1 ; Chl b = 29.2 ± 0.1 mg 100 g −1 and total Chl = 96.1 ± 0.2 mg 100 g −1 ) at 50° C. The literature reported degradation of Chls above 80 °C combined with high pressure for degradation, suggesting that at the temperatures of this work the thermal degradation should be very low. For spinach, an optimum temperature of 41 °C was observed for Chls extraction using non‐ionic surfactants …”

“…52 The highest extraction (Chl a = 41.1 ± 0.5 mg 100 g −1 ; Chl b = 17.2 ± 0.2 mg 100 g −1 and total Chl = 58.3 ± 0.7 mg 100 g −1 ) was reached using 5 wt% of Triton X-100. Leite et al 53 reported that low surfactant concentrations allowed greater biocompatibility of the extractant's aqueous solution as well as better economic viability. However, high surfactant concentrations did not lead to an improvement in the extraction process.…”