Optimisation of Organic Solvent Mediated Solubilisation of Apple Pomace Polyphenolic Compounds Using Response Surface Methodologies

Abstract

Polyphenolic compounds extraction from industrial apple pomace was optimised by applying design of experiments (DoE) and surface response methodology using the Central Composite Rotatable Design (CCRD). The degree solubilisation and the yield of total phenolic content from the apple pomace using organic solvents was shown to be influenced by process parameters including solvent type, solvent concentration, temperature, apple pomace to solvent ratio, and extraction time (residency time). Optimal conditions of extracting phenolic compounds were as follows: acetone concentration, 65 % (v/v); solid to solvent ratio 1 %; extraction time 30 minutes and temperature 60oC. Optimum condition for solubilisation was as follows: acetone concentration 78 % (v/v); solid to solvent ratio 4.7 %; extraction time 54 minutes and temperature 21oC. Under these conditions, the total phenolic content and solubilisation were 21.70 ± 0.2 mg GAE/g dw and 19.20 ± 0.1g/100g of the dried apple pomace respectively and largely agreed with those predicted by the Stat-Ease software. Independent variables for optimisation of total phenolic content and solubilisation were completely different. The reverse phase HPLC analysis of the extract revealed the major polyphenolic compounds were chlorogenic acid, procyanidin B2, caffeic acid, epicatechin, ferulic acid, quercetin-3-galactoside, quercetin-3-glucoside and phloridzin.

Kinetic modelling of the solid–liquid extraction process of polyphenolic compounds from apple pomace: influence of solvent composition and temperature

“…Solid–liquid extractions using three different solvents of water-only (designated as 100 WA henceforth), 50% ethanol–50% water v/v (designated as 50 ETH henceforth), and 65% acetone–35% water v/v (designated as 65 ACE henceforth) were carried out for the recovery of polyphenolic compounds present in dry AP sample. To this end, the extraction operating parameters were selected based on previous optimization studies for enhanced TPC extraction (Candrawinata et al 2014 ; Ibrahim et al 2019 ; Zardo et al 2020 ). Optimal TPC extraction with 100 WA was attained at solid (dry apple pomace) mass-to-solvent volume ratio of 1:20 g/mL (Candrawinata et al 2014 ).…”

“…The optimal TPC extraction using ethanol has been achieved using 50 ETH and a solid-to-solvent ratio of 1:80 g/mL (Zardo et al 2020 ). When 65 ACE was employed, the solid-to-solvent ratio of 1:100 g/mL was imposed (Ibrahim et al 2019 ). The experiments were undertaken in a 50 mL laboratory flask with continuous stirring at 200 rpm.…”

Effect of Extraction Conditions for Recovery of Chlorogenic Acid and Flavonoids from Wet Cider Apple Pomace under Subcritical Water

“…Monomeric procyanidins like catechin and epicatechin were barely detected and the reason could be that the UV-DAD was not very good enough for their detection. Protocatechuic aldehyde was detected from 100 o C,150 o C and 200 o C. The HPLC -DAD characterisation of the polyphenolic compounds of subcritical conditions at 100 o C reveals among others similar compounds under the aqueous acetone extraction (Ibrahim et al, 2019). These polyphenolic compounds with exception of protocatechuic aldehyde were the main polyphenolic compounds recovered from apple pomace using pressurised ethanol/water as solvents.…”

Predictive Models for Optimisation of Acetone Mediated Extraction of Polyphenolic Compounds from By-Product of Cider Production

“…The design of the experiments was done similar to the procedure previously described in [18]. The design was composed of one factor at a time (OFAT) experiments and the overall design by response surface methodology (RSM).…”