Effect of Ultrasound on Henna Leaves Drying and Extraction of Lawsone: Experimental and Modeling Study

Abstract

The effect of drying temperature and the application of ultrasound on drying kinetics of Lawsonia inermis (henna) leaves and the extraction of lawsone from the dried samples was addressed. Indeed, henna leaves were dried with and without the application of ultrasound (21.7 kHz, 30.8 kW/m3) at 40, 50 and 60 °C with a constant air velocity (1 m/s). As expected, both the increase of temperature and the application of ultrasound decreased the drying time and increased the rate of extraction of the lawsone. The values of the effective diffusion coefficients obtained were used to quantify this influence showing the value increases with higher drying temperature and the application of ultrasound. Moreover, the influence of temperature was quantified by the estimation of the activation energy from an Arrhenius-type equation (46.25 kJ/mol in the case of drying without ultrasound application and 44.06 kJ/mol in the case of ultrasonically-assisted drying). Regarding the influence of studied variables on lawsone extraction yield, the higher is the temperature, the lower is the yield, probably linked with lawsone degradation reaction due to thermal treatment. On the contrary, the application of ultrasound improved the extraction yield mainly at the lower drying temperature tested of 40 °C.

Influence of convective and microwave drying on Algerian blood orange slices: Drying kinetics and characteristics, modeling, and drying energetics

“…These results were in agreement with the studies of Bennaceur et al (2021) and Evin (2012), and Mouhoubi, Boulekbache‐Makhlouf, Mehaba, et al (2022).…”

“…The advantage of using microwave for a significant reduction of drying time has been found in other works for different fruits (Agbede et al, 2020;Amini et al, 2021;Bennaceur et al, 2021;Chen et al, 2020;Mouhoubi et al, 2020).…”

“…At this stage, a decrease in drying rate with a decrease in moisture content is rapid. Below the specific moisture content, the remaining moisture is bound to the matrix, which has lengthened the internal moisture transfer pathways and generates the decrease in drying rate, drying has become limited by moisture transfer (Bennaceur et al, 2021; Chen et al, 2020). In fact, increasing the microwave power and temperatures significantly increased the average drying rate to 23.59 and 28.86 kg water/kg dm min kg dry matter min −1 at 600 and 800 W (about 3.5 times that at 200 W) and 1.26 and 2.00 kg water/kg dm min kg dry matter min −1 at 100°C and 120°C (about 14, 3 times that at 40°C), respectively.…”

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“…The drying process of the simplicial material was carried out by using an oven at 30 to 90 °C with an optimum temperature of 60 °C for 12 hours to produce dry brown henna leaves. The drying process is very important in the simplicial manufacture because reducing the water content and stopping the enzymatic reactions prevents the deterioration of quality and the destruction of simplicial [21,23]. Oven drying had higher levels of flavonoids because the heating temperature occurring in the oven was more evenly distributed, and the resulting air circulation was perfect, thus optimizing the drying process.…”

“…Moreover, nail henna includes naphthoquinone (lawsone), tannins, coumarin, xanthones, flavonoids, phenolic derivatives, aliphatic components, sterols, and triterpenes [19]. It also includes other chemical constituents such as amino acids, glucose, gallic acid, minerals, mannitol, and trace elements [21]. Lawsone, the main ingredient and coloring agent in leaves, comprises 2-hydroxy and 1.4 naphthoquinone with a concentration of 1.0-1.4%.…”