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. 2018 Jan 2;6(1):590-599.
doi: 10.1021/acssuschemeng.7b02931. Epub 2017 Nov 8.

Cloud point extraction of chlorophylls from spinach leaves using aqueous solutions of non-ionic surfactants

Ana Cláudia Leite #  1 , Ana M Ferreira #  1 , Eduarda S Morais  1 , Imran Khan  2 , Mara G Freire  1 , João A P Coutinho  1
Affiliations

Cloud point extraction of chlorophylls from spinach leaves using aqueous solutions of non-ionic surfactants

Ana Cláudia Leite et al. ACS Sustain Chem Eng. .

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.

Keywords: Solid-liquid extraction; antioxidant activity; aqueous solutions; concentration; non-ionic surfactants; spinach leaves, chlorophylls.

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Figures

Figure 1
Figure 1
Chemical structure of chlorophylls a and b.
Figure 2
Figure 2
Extraction yield of chlorophyll a (■) and chlorophyll b (■) from spinach leaves using (A) several surfactants aqueous solutions (surfactant concentration=3.3 mM; R=0.02; t=30 min; T=25 °C) and water; and (B) organic solvents (R=0.02; t=30 min; T=25 °C) and ratio of chlorophyll a/b (◆). (C) Relationship between the HLB values of surfactants and the total extraction yield of chlorophylls from spinach leaves. (D) Extraction yield of chlorophyll a (■) and chlorophyll b (■)from spinach leaves using mixtures of Briji 30 and Briji 98 with different HLB values (R=0.02; t=30 min; T=25 °C) and ratio of chlorophyll a/b (◆).
Figure 3
Figure 3
Response surfaces corresponding to the chlorophylls extraction yields with the following combined parameters: (A) solid-liquid ratio and surfactant concentration; (B) solid-liquid ratio and temperature; and (C) surfactant concentration and temperature.
Figure 4
Figure 4
SEM images of the original spinach leaves, and of spinach leaves after the extraction with water, with an aqueous solution of C11-C13 9EO’s at 12.4 mM and with ethanol.
Figure 5
Figure 5
Scheme of the process used to concentrate chlorophylls.
Figure 6
Figure 6
IC50 values (μg/mL) after 0.5 (■), 1.5 (■) and 2h (■) of exposure to DPPH.
Figure 7
Figure 7
Scheme of the developed extraction-concentration process for chlorophylls from spinach leaves using aqueous solutions of non-ionic surfactants.
See this image and copyright information in PMC

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