Optimisation of aqueous extraction conditions for the recovery of phenolic compounds and antioxidants from lemon pomace

Abstract

Summary The aim of this study was to optimise the aqueous extraction conditions for the recovery of phenolic compounds and antioxidant capacity of lemon pomace using response surface methodology. An experiment based on Box–Behnken design was conducted to analyse the effects of temperature, time and sample‐to‐water ratio on the extraction of total phenolic compounds, total flavonoids, proanthocyanidins and antioxidant capacity. Sample‐to‐solvent ratio had a negative effect on all the dependent variables, while extraction temperature and time had a positive effect only on TPC yields and ABTS antioxidant capacity. The optimal extraction conditions were 95 °C, 15 min and a sample‐to‐solvent ratio of 1:100 g mL−1. Under these conditions, the aqueous extracts had the same content of TPC and TF as well as antioxidant capacity in comparison with those of methanol extracts obtained by sonication. Therefore, these conditions could be applied for further extraction and isolation of phenolic compounds from lemon pomace.

Effect of vacuum‐drying, hot air‐drying and freeze‐drying on polyphenols and antioxidant capacity of lemon (Citrus limon) pomace aqueous extracts

“…The lemon peel aqueous extracts were prepared according to Papoutsis et al (2016) with minor modifications. Briefly, dried lemon peels (0.1 g) were extracted using hot water (10 mL) at 95 AE 1°C for 15 min in a water bath (Ratek Instruments Pty.…”

“…Total phenolic content (TPC) TPC was determined according to Papoutsis et al (2016). The absorbance was measured at 760 nm using UV spectrophotometer (Varian Australia Pty.…”

“…-CUPRAC assay was determined as described by Papoutsis et al (2016). -CUPRAC assay was determined as described by Papoutsis et al (2016).…”

Radical scavenging and anti‐proliferative capacity of three freeze‐dried tropical fruits

“…These new results are not in agreement with those from a previous study (Quirós‐Sauceda et al ., ) where DPPH and ABTS values, when expressed as μmol of trolox equivalents/100 g fresh weight, were not different ( P > 0.05) between fresh mango, papaya and pineapple. Many factors may explain this discrepancy including differences in the ripening stage of fruits (Gayosso‐García Sancho et al ., ; Palafox‐Carlos et al ., ), the harmonisation of radical scavenging capacity results as trolox equivalents (Marino et al ., ) or the low density (sample‐to‐water ratio) of extractable phytochemicals per gram of fresh fruit (Papoutsis et al ., ). Lastly, the radical scavenging capacity expressed as the concentration of freeze‐dried extracts providing 50% inactivation of each radical (EC 50 ) highly correlated with each other ( r s = 0.98), with ascorbic acid ( r s = −0.94) and with total phenolic compounds ( r s = −0.68) content; but poorly with flavonoids ( r s = 0.48) content, in agreement with our previous reports in fresh fruits (Corral‐Aguayo et al ., ; Gayosso‐García Sancho et al ., ; Palafox‐Carlos et al ., ).…”

Microwave irradiation enhances the in vitro antifungal activity of citrus by‐product aqueous extracts against Alternaria alternata

“…Total phenolic content (TPC) The TPC of the crude extracts was determined according to Papoutsis et al (2016b). Briefly, 1 mL of crude extract was mixed with 5 mL of 10% (v/v) Folin-Ciocalteu reagent.…”