Valorization of apple tree wood residues by polyphenols extraction: Comparison between conventional and microwave-assisted extraction

Abstract

For the first time, the characterization of antioxidant activity and phenolic profile of apple tree (Malus domestica) bark, core and roots was carried out. Phenolic compounds were extracted from the Belgium apple tree wood residues collected at two seasons, namely summer 2015 and winter 2016, using conventional (CE) and microwave-assisted extraction (MAE) techniques. For each extraction technique, the influence of the most important operational parameters, namely solvent composition, extraction time and temperature, on the total phenolic and flavonoid content, and antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH-RSA) and ferric reducing activity power (FRAP) assays were optimized. The phenolic profile from the obtained extracts was also characterized by high-performance liquid chromatography with photodiode array detection (HPLC-PDA). Optimum conditions were: 20 mL ethanol:water 60:40 v/v, 20 min, 100 °C, sample weight 0.1 g for MAE and 20 mL ethanol:water 50:50 v/v, 2 h, 55 °C, sample weight 0.5 g for CE. Root extracts obtained by MAE (the most efficient technique) presented the highest phenolic (47.7 ± 0.9 mg gallic acid equivalents/g dry weight) and flavonoid (17.1 ± 0.8 mg epicatechin equivalents/g dry weight) content, and antioxidant activity (28.4 ± 2.0 mg trolox equivalents/g dry weight and 36.1 ± 2.7 mg ascorbic acid equivalents/g dry weight for DPPH-RSA and FRAP assays, respectively), followed by bark and core wood extracts. HPLC-PDA analysis revealed that phloridzin was the main contributor to the phenolic composition representing 52%-87% of the total amount of phenolic compounds quantified, while phenolic acids represents less than 10%. This study reveals the potential of apple tree wood residues valorization through the recovery of phenolic compounds for food, pharmaceutical and cosmetic applications.

Valorization of fruits and vegetables waste through green extraction of bioactive compounds and their nanoemulsions-based delivery system

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Increasing the Sustainability of the Coffee Agro-Industry: Spent Coffee Grounds as a Source of New Beverages

“…Microwave-assisted extraction (MAE) is a technology of interest to the industry, which represents an alternative to conventional extraction processes [5]. This technique has little impact on the environment, compared to traditional techniques, and MAE has aroused great interest for its application in the extraction of high-value compounds.…”

Two Kaempferol Glycosides Separated from Camellia Oleifera Meal by High‐Speed Countercurrent Chromatography and Their Possible Application for Antioxidation

“…In addition, we also found that MAE requires the least consumption of solvents, indicating that it can greatly save the production cost. Indeed, more efficient extraction of phytochemicals from other plant materials has also been reported by using MAE compared with other new or conventional techniques including UAE, HRE, and CSE (Dahmoune, Nayak, Moussi, Remini, & Madani, 2015;Moreira, 2017;Saleh et al, 2017). Considering the high consumption of time and solvents by traditional extraction techniques, MAE is more suitable for the extraction of FG from C. oleifera meal, and can be a promising, economical, environment friendly, and simplified method for the large-scale production of FG.…”