Thymus schimperi Ronniger is a wild endemic herb to Ethiopia, and is traditionally used as food flavoring, preservative as well as medicinal ingredient. This paper reports the total phenolic and flavonoid contents, antioxidant capacity and α-amylase inhibition activity of various solvent extracts of the dried leaves. The acetone extracts contained the highest total phenolic content (122.0±11.6 mg GAE/g). Total flavonoid content was the highest in methanol extract (45.1±2.9 mg QRE/g). The aqueous methanol extract showed the highest 2,2-diphenylpicrylhydrazyl (DPPH) radical scavenging ability (IC 50 =11.0±1.0 µg/ml), iron reducing power (60.1±1.0 mg AAE/g), and total antioxidant capacity (1.1±0.1 mg BHTE/g). The water extract exhibited the highest iron chelating activity (IC 50 = 65.4±1.1 µg/ml) while the methanol extract exhibited the highest percentage of α-amylase inhibition activity (IC 50 = 335. 6±90.4 µg/ml). Except for iron chelating activity, all antioxidant activities were positively correlated with total phenolic and flavonoid contents. The study revealed that antioxidant and α-amylase inhibitory activities of the crude extract were variable when extracted by different solvents indicating a high potential to be used as natural antioxidants in food preservation as well as for preventing oxidative stress mediated human disorders.

This study investigated total phenolic contents (TPC), total flavonoid contents (TFC), antioxidant activity, and antibacterial activities of different leaf extracts of Measa lanceolata. The TPC and TFC of the extracts were determined by Folin-Ciocalteu and aluminum chloride methods, respectively. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, reducing power, and phosphomolybedinium assays were used to evaluate antioxidant activity. Antibacterial properties were assessed using the disc-diffusion assay based on minimum inhibitory concentration (MIC). Bacteria tested were three strains of gram-negative (Escherichia coli (ATCC-25922), Proteus vulgaris (ATCC-13315), and Pseudomonas aeruginosa (ATCC-43495)), and two strains of gram-positive (Staphylococcus aureus(ATCC-25923), and Enterococcus faecalis(ATCC-29212)). It was found that methanol extract contained the highest TPC (60.6 ± 4.4 mg of gallic acid equivalent/g of dried extract) and TFC (6.4 ± 6.0 mg of catechin equivalent/g of dried extract). Extract showed the strongest DPPH radical scavenging activity (EC 50 = 76.7 ± 7.3 µg/mL), iron reducing power (EC 50 = 74.0 ± 1.6 µg/mL), and total antioxidant activity (128 ± 4 mg of ascorbic acid equivalent per dried extract). Inhibition zones were observed in water and methanol extracts against bacterial strains, whereas Staphylococcus aureus (ATCC-25923), Escherichia coli(ATCC-25922), Pseudomonas aeruginosa (ATCC-43495), and Proteus vulgaris(ATCC-13315) were resistant against chloroform and ethyl-acetate extracts.

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Flavor instability resulting from beer storage and oxidation is the most important quality‐related problem in the brewing industry. This study evaluated the influence of adding 80% ethanolic extract of Moringa stenopetala leaf to lagered beer at 400, 600, and 800 ppm concentrations for 30‐, 60‐, and 90‐day storage time at room temperature. The effect of physicochemical properties of the beer incorporated with leaf extract of Moringa stenopetala (LEMS) was evaluated using the American Society of Brewing Chemists method of analysis. Sensory acceptability of the beer treated with LEMS was evaluated using nine hedonic scales over a period of storage time. Original gravity (11.06–11.08), apparent extract (3.68–3.77), pH (4.23–4.40), vicinal diketone (0.07–0.09), and alcohol content (4.76–4.81) were not altered by the incorporation of LEMS at any level of treatment and over a period of storage time. The beer color (8.88–9.70 EBC), bitterness (13.62–15.56 bitterness unit), calcium ion (44.18–52.04 ppm), and foam stability (201.5–246.5) of beer increased with increasing LEMS concentration, but a significant haziness reduction (1.23–0.63) was observed. However, the storage time decreased both haziness and foam stability of LEMS‐incorporated beer. The incorporation of LEMS at an optimum level kept its quality for 90 days better than the usual antioxidant (potassium metabisulfite) added in beer. The sensory analysis also supported the beer treated with 600 ppm of LEMS as the best overall acceptability. The result indicates a promising use of LEMS as a functional ingredient in beer to reduce beer oxidation probability and keep its freshness for a period of storage time.