Arbutus unedo fruit syrup as a fortifying agent: effect on physicochemical, microbiological, rheological, sensory and antioxidant properties of yoghurt.

This study aims to assess the antioxidant and the antibacterial activities of Arbutus unedo fruits and to valorize its syrup by the incorporation in bi-layer yoghurt. The antioxidant activity of the ethanol 80% fruits and syrup extracts was evaluated by three methods namely DPPH·, ABTS·+ and FRAP. The antibacterial activity was tested against seven pathogenic bacteria using agar well diffusion method. The yoghurt was prepared using 10 and 20% layers of A. unedo syrup, physicochemical, rheological, microbiological and sensorial characteristics and the antioxidant activity were investigated during cold storage. The results revealed that the heat treatment decreased the phenolic compounds contents and the antioxidant activity in the syrup extract. Both fruits and syrup extracts demonstrated an antibacterial activity against the tested bacteria. The highest inhibition diameter (40 mm) was recorded for Aeromonas hydrophila at 100 mg/mL of fruit echtanolic extract. The prepared bi-layer yoghurts showed stability for the physicochemical and microbiological properties during storage. The rheological properties revealed that the A. unedo syrup increases the yoghurt consistency (k). The antioxidant activity of the yoghurt indicated that fermentation improved the radical scavenging power of the A. unedo syrup at the beginning and the activity decreased slowly during storage. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05801-4.

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

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.

Physico-Chemical Characterization of Tunisian Canary Palm (Phoenix canariensis Hort. Ex Chabaud) Dates and Evaluation of Their Addition in Biscuits.

Phoenix canariensis Hort. Ex Chabaud, also known as the Canary Island palm or ornamental palm, is an endemic species of the Canary Islands and has been widely propagated globally. It has become one of the most important and appreciated ornamental plants, especially in the Mediterranean climate. The fruits are edible but used only for feed as they are bitter. Despite its diffusion, not much data on the composition of these fruits and their application as food are available. The aim of this study was to define the chemical characteristics, especially those of the polyphenolic constituents, of red and yellow varieties of Canary palm dates, and to evaluate their use alone or in different mixes in biscuit production. The yellow variety had higher quantities of fiber (36.88% DW (Dry Weight)) and polyphenolic compounds, while the red variety had a high content of sugars, mainly glucose (22.8% DW). Epicatechin is the most important polyphenol of dates (562 mg/g DW). The use of date palm powder on biscuit production resulted in an increase in hardness, polyphenol and fiber content, and antioxidant activity. Sensory analysis showed that the biscuits obtained with a 25/75 mix of red/yellow date powder had the most overall liking.