Green Extraction Techniques for Obtaining Bioactive Compounds from Mandarin Peel (Citrus unshiu var. Kuno): Phytochemical Analysis and Process Optimization.

Silvija Šafranko,Igor Jerković,Krunoslav Aladić,Martina Jakovljević,Ina Ćorković,Drago Šubarić,Stela Jokić

doi:10.3390/foods10051043

Silvija Šafranko, Igor Jerković + Show 5 more

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https://doi.org/10.3390/foods10051043

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Abstract

In this study, an efficient utilization and valorization of mandarin peel (Citrus unshiu Marc. var. Kuno) was investigated using innovative and green extraction techniques. The first step of this study included the extraction and analysis of the volatile compounds by performing a supercritical CO2 (SC-CO2) extraction under different operating pressure conditions (100 and 300 bar). The analysis of volatile compounds of the obtained extracts was conducted by gas chromatography-mass spectrometry (GC-MS), and limonene was found to be the dominant volatile component (13.16% at 100 bar; 30.65% at 300 bar). After SC-CO2 treatment, the exhausted citrus peel waste enriched with bioactive compounds was subjected to subcritical water extraction (SWE) in a wide temperature range (130–220 °C) using different solvent-solid ratio (10–30 mL/g) in time periods from 5 to 15 min, in order to obtain bioflavonoids. Identification and quantification of present bioflavonoids was conducted by high-performance liquid chromatography with a with a diode array detector (HPLC), and hesperidin (0.16–15.07 mg/g) was determined as the most abundant flavanon in mandarin peel with other polyphenolic compounds that were possible by-products of thermal degradation. At higher temperatures, the presence of 5-hydroxymethylfurfural (5-HMF) and chlorogenic acid were detected. Antiradical activity and total phenolic content in the extracts were determined using spectrophotometric methods, while the process optimization was performed by response surface methodology (RSM).

Highlights

The main goal of the industry is to develop and ensure high-quality products followed by the efficient utilization of raw material, minimizing food loss and management costs, reducing industry waste
In order to compare the efficiency of the extraction on the yield and the composition of volatile components by supercritical CO2 (SC-CO2) method, the variations in two operating pressures (100 and 300 bar) were employed
The results have indicated that the significant concentrations of the compounds 5-HMF, hesperidin, narirutin, rutin, and chlorogenic acid were detected in the obtained extracts

Summary

Introduction

The main goal of the industry is to develop and ensure high-quality products followed by the efficient utilization of raw material, minimizing food loss and management costs, reducing industry waste. The novel scientific studies are focused on the valorization of citrus residue with the primary objective of developing of innovative products enriched with bioactive compounds with the emphasis on the efficient waste utilization [5,11,12,13]. Limonene is predominant monoterpene in citrus peel, while in lower concentrations linalool, octanal, citronellal can be detected in natural citrus peel essential oils [5,17]. It is well-known that citrus peels are rich in phenolic components, among which flavonoids are most commonly studied due to their beneficial effects to human health [14,15,17]. Other important and beneficial flavonoids are narirutin, rutin, diosmin, didymin, sinensetin, and tangeretin which could be detected in small quantites or are available in traces in citrus extracts [22]

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