Effects of process parameters on supercritical CO₂ extraction of total phenols from strawberry (Arbutus unedo L.) fruits: An optimization study

Abstract

The aim of this work was to optimize total phenolic yield of Arbutus unedo fruits using supercritical fluid extraction. A Box-Behnken statistical design was used to evaluate the effect of various values of pressure (50-300 bar), temperature (30-80°C) and concentration of ethanol as co-solvent (0-20%) by CO2 flow rate of 15 g/min for 60 min. The most effective variable was co-solvent ratio (p<0.005). Evaluative criteria for both dependent variables (total phenols and radical scavenging activity) in the model were assigned maximum. Optimum extraction conditions were elicited as 60 bar, 48°C and 19.7% yielding 25.72 mg gallic acid equivalent (GAE) total phenols/g extract and 99.9% radical scavenging capacity, which were higher than the values obtained by conventional water (24.89 mg/g; 83.8%) and ethanol (15.12 mg/g; 95.8%) extractions demonstrating challenges as a green separation process with improved product properties for industrial applications.

Antioxidant potential of Juglans nigra, black walnut, husks extracted using supercritical carbon dioxide with an ethanol modifier

“…, ; Akay et al. ; Pieszka et al. ) For walnut husk extraction, an extensive literature review reveals that investigators commonly dry the walnut husks at various temperatures prior to extraction, Table .…”

“…(Pohler and Kiran 1997) A similar increase in antioxidant potential and total phenolic content was also observed in the supercritical carbon dioxide extraction of both strawberries and grape seeds as ethanol content increased from 0 to 20%. (Murga et al 2000;Akay et al 2011) For both TPC and FRAP analysis, the highest antioxidant potential was observed at an extraction condition of 68°C with 20 wt-% ethanol. It may be possible that even higher temperatures and ethanol content can result in higher antioxidant potential extractions, however, there are practical concerns as more extreme conditions are reached.…”

“…This has been done in for a variety of extraction studies involving berries, such as strawberry, chokeberry, and grapes, leaves of berry crops, and nuts, such as walnuts. (Oliveira et al 2008(Oliveira et al , 2013Akay et al 2011;Pieszka et al 2015) For walnut husk extraction, an extensive literature review reveals that investigators commonly dry the walnut husks at various temperatures prior to extraction, Table 3. There are many reasons to dry plant matter: to prevent spoilage for better storage until time of use, to concentrate the chemicals in the plant TPC, total phenolic content 1 mg GAE/g husk 2 mg GAE/g extract matter, or to control the variability that moisture may present.…”

Recent Advances in Supercritical Fluid Extraction of Natural Bioactive Compounds from Natural Plant Materials

“…Studies on the influence of temperature and pressure on the extraction process of bioactive substances gave different results due to the plant materials and targeted compounds [ 40 , 42 , 44 , 45 , 46 , 47 , 48 ]. For example, high pressures were reported to enhance the global extraction yield of phenolic compounds [ 40 , 45 , 47 ], while Akay et al [ 46 ] reported a high total phenolic content under low pressure and no significant difference to the yield when increasing temperature and pressure. Some results showed that an augmentation in the recovery of phenolic compounds could be obtained by reducing the extraction temperature and increasing the addition of co-solvent and pressure [ 45 ].…”

Arbutus unedo L.: Chemical and Biological Properties

“…The extracts of A. unedo fruits revealed to have in vitro antioxidant activity [26,29,36,37,40,58,59,60,61,62]. The type of extraction of phenols present in fruits of A. unedo influenced the antioxidant activity.…”