engleski

Integrated green approach to extraction of bioactive compounds from orange peel dust-waste generated in the filter tea factory

Orange peel waste (OPW), as a by-product of the citrus processing industry, and it represent a rich source of bioactive compounds. During processing in the filter tea industry, a large amount of material with a particle size <0.315 mm remains, which is eventually disposed of, as it can not be used in the further production of filter tea form. This fraction is called herbal dust of orange peel (OPD) and is a raw material that can be valorized and used as a potential source of various high-value compounds (polyphenols, carotenoids, dietary fiber, sugars, essential oils, etc.). Conventional extraction methods can be used to isolate these compounds, however, due to the insufficient efficiency and cost-effectiveness of these methods, there is a problem of low recovery of citrus agro-industry waste. Therefore, in this paper, the emphasis is on "green", attractive extraction methods. The use of supercritical carbon dioxide (SFE- CO2) extraction is widely recognized as a safe and effective solution to the problems that accompany conventional methods. According to the green concept, SFE-CO2, in addition to being faster and more efficient, also prevents the decomposition of thermolabile compounds, avoiding the use of toxic solvents, enabling the production of solvent-free extracts. This method was used as a pre-treatment for the ultrasound- assisted extraction (UAE). The UAE is considered a cheap, simple and efficient extraction technique for obtaining extracts of better and more uniform composition in a significantly shorter time and lower energy consumption. The efficacy of UAE for the isolation of bioactive compounds from OPD with SFE-CO2 pretreatment was investigated using an ultrasonic probe. During the SFE-CO2 process, the extraction time was 4 h, the temperature was kept constant (40ᵒC), and the extraction pressure (100-300 bar) varied. After that, UAE was performed where the sonication amplitude (20-100%) was varied, while the temperature was defined as a constant (50ᵒC). Changes in extraction time, ultrasonic power and energy consumption were observed. The chemical composition of the obtained extracts was assessed by HPLC. Compounds identified as dominant are hesperidin, naringin, narirutin and rutin. Hesperidin stands out as the most dominant compound, whose concentration ranged between 848 ± 6.50 to 884.64 ± 21.59 (ug / ml) depending on the applied process parameters. The results show that pre-treatment of SFE-CO2, followed by the use of UAE using an ultrasonic probe can significantly improve the extraction of valuable compounds from plant material, thus proving to be a value-added process and a potentially efficient technique used at the industrial level.

orange peel ; herbal dust ; ultrasound-assisted extraction ; supercritical extraction ; bioactive compounds

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