Drying methodology effect on the phenolic content, antioxidant activity of Myrtus communis L. leaves ethanol extracts and soybean oil oxidative stability

Abstract

In this study, different drying methodologies (convective air, oven and microwave) of Myrtus communis L. (M. communis L.) leaves were conducted to investigate their effects on the levels of phenolic compounds, antioxidant capacity of ethanolic extracts (EEs) as well as the soybean oil oxidative stability. Drying methodology significantly influenced the extractability of phenolic compounds. Microwave drying led to an increase in the amounts of total phenols, flavonoids and proanthocyanidins followed by oven drying at 70 °C. Higher temperature of drying (100 and 120 °C) led to a significant reduction of their amounts (p < 0.05). An ultra-performance liquid chromatography method combined with high resolution mass spectroscopic detection was used to analyze the phenolic fraction of extracts. Higher amounts of the identified compounds were observed when leaves were heat treated. Furthermore, the evaluation of the antioxidant activity showed that the studied extracts possess in general high antioxidant capacities, significantly dependent on the employed drying methodology. The incorporation of the different extracts at 200 ppm in soybean oil showed that its oxidative stability was significantly improved. Extracts from leaves treated with microwave (EE_MW) and at 70 °C (EE_70) have better effect than BHT. The results of the present study suggest that microwave drying could be useful to enhance the extractability of phenolic compounds and the antioxidant capacity of M. communis L. leaf extract.

Comparative Study on the Essential Oils Extracted from Tunisian Rosemary and Myrtle: Chemical Profiles, Quality, and Antimicrobial Activities

“…Moreover, the findings of the MEO activity in the present study are higher than those previously reported for another Tunisian one, although 1,8-cineole and α-pinene were the major components for both oils. The same was also true in the case of another Tunisian essential oil …”

Investigation into Solar Drying of Moroccan Strawberry Tree (Arbutus unedo L.) Fruit: Effects on Drying Kinetics and Phenolic Composition

“…Drying method can vary in their effect on phenolic compounds, and this is mainly attributed to the drying temperatures. Snoussi et al, (2021) reported a double fold increase in phenolic compounds content in Myrtus communis L. [80] when dried via microwave than in air dried samples, whereas, oven drying at higher temperature (100 and 120 • C) resulted in significant reduction (30% and 60% reduction at 100 and 120 • C, respectively). Also, Ho and Lin (2008) showed that applying low temperatures (<100 • C) to dry citrus peels reduced the destructive power on the most key phenolic compounds as compared to higher temperature (150 • C) [81].…”

<em>Myrtus communis </em>Leaves: Source of Bioactives, Traditional Use and their Biological Properties

“…Among them microwave drying of the leaves led to an increase in the amounts of total extractible phenols, flavonoids and proanthocyanidins followed by oven drying at 70 °C. Not only the amount of compounds isolated was more, but also their antioxidant activity was enhanced (31). The concentration of bioactive compounds in myrtle berries is related to their geographical origin, as myrtle berries collected in two different areas of the province of Cadiz (Spain) showed different concentration of bioactives (32).…”