Extraction of polyphenols from black tea – Conventional and ultrasound assisted extraction

Abstract

Products from plant raw materials gain increasing importance in food-, cosmetics and pharmaceutical industry. By way of contrast, due to lack of detailed physico-chemical fundamentals, existing production processes are economically not optimal designed. This leads to a need for deeper understanding of the processes and furthermore a systematic process and equipment design for the potentially applicable extraction techniques. Using the example of polyphenol extraction from black tea (Kenya), the conventional and ultrasound assisted extractions are investigated. Here, the state of the art as well as a comparison between the two techniques is in focus. Especially, resulting quasi-equilibria and mass transport kinetics serves as a criteria. The physico-chemical background is discussed taking particle size distributions and scanning electron microscope (SEM) measurements into account. Conclusively, process alternatives are projected and discussed. Hence, the present study makes influences of ultrasound technique on physico-chemical characteristics during extraction a subject of discussion.

Polyphenols extraction from plant sources

“…These mechanical and thermal effects cause the degradation of cell walls, release of cell contents, a greater penetration of solvent into plant material, the increment of mass transfer and thus, the increase of polyphenols yield (Deng et al, 2015;Horžic et al, 2012). Particle size of plant material does not significantly affect polyphenols yield, since ultrasound waves induce reduction of the particle size (approximately 5%), damage of the cells and modification of microstructure, which results in the increase of solvent penetration into herbal matrix and in the higher polyphenols release, regardless of the initial size of plant particles (Both et al, 2014;Deng et al, 2015;Jovanović et al, 2017). Regarding the selection of the extraction medium for ultrasound-assisted extraction, alcohol/water mixture was the most suitable solvent for maximum recovery of polyphenols from Jatropha dioica, Eucalyptus camaldulensis, Origanum majorana and Thymus species, whereas pure alcohol or water could not completely extract polyphenols (Chizzola et al, 2008;Fecka and Turek, 2008;Wong Paz et al, 2015).…”

“…These methods are simple, but involve several disadvantages such as low polyphenols yield, long extraction time and large amounts of plant material and solvent (Mustafa and Turner, 2011;Wang and Weller, 2006). In the recent time, the application of novel extraction procedures, such as ultrasound-assisted, microwave-assisted, supercritical fluid, accelerated solvent and pressurized liquid extractions, have been evaluated (Both et al, 2014;Dahmoune et al, 2015;Milošević et al, 2011;Mustafa and Turner, 2011;Oniszczuk and Podgorski, 2015). According to the literature data, these methods provide various benefits which include higher yield of polyphenols, shorter extraction time, ie.…”

Impact of ultrasound on solid–liquid extraction of phenolic compounds from maritime pine sawdust waste. Kinetics, optimization and large scale experiments

“…The second objective of this work was to identifying optimal range of UAM extraction conditions namely the ultrasonic intensity (UI), the processing temperature (T) and the processing time (t) and to develop an effective and eco-friendly ultrasound-assisted extraction strategy for extraction of polyphenol compounds from maritime pine sawdust waste, using response surface methodology. In the third part, three concepts were investigated and compared: conventional multi-stage maceration, ultrasound assisted multi-stage maceration and a combination between them [22] in order to highlight the impact of ultrasound. Moreover, a pilot plant reactor of 30 L extraction tank was investigated at lab optimum conditions to prove that the scale up of the process is possible.…”

New method to enhance the extraction yield of rutin from Sophora japonica using a novel ultrasonic extraction system by determining optimum ultrasonic frequency

“…Recently, many studies have reported that higher extraction yields could be achieved when an UAE method was adopted on many plant products, such as rutin from flower buds of Sophora japonica [7], oil from tobacco (Nicotiana tabacum L.) seeds [8], carvone and limonene from caraway seeds [9], polyphenols from black tea [10], extraction of carotenoids [11], pectins from grape pomace [12], D-pinitol from carob pods [13], and vanillin from vanilla pods [14]. Those studies mainly looked at optimization of other extraction conditions with regards to efficiency and/or yield.…”