Chemical properties and antioxidant activity of sweetened red ginger extract fermented with kombucha culture

Kombucha is a renowned fermented drink for its diverse health benefits. This research aims to evaluate sweetened red ginger extract as an alternative substrate in making kombucha by observing the chemical properties (pH, total acid, total sugar, total polyphenol, chemical compound profile using LC-MS/MS) and the antioxidant activity. Three variables were varied, i.e., red ginger concentration (1, 5, and 10%), kombucha culture concentration (10 and 20%), and fermentation time (0, 6, and 12 days). The total sugar and pH declined during fermentation while the titratable acidity, polyphenol, and antioxidant activity increased. The kombucha prepared with 20% culture concentration resulted in a greater reduction of pH and increase of titratable acidity, total polyphenol, and antioxidant activity than the one prepared with 10% culture concentration. The red ginger kombucha prepared with 10% ginger and 20% culture in 12 days displayed the highest antioxidant activity. It revealed ten active compounds under the LC-MS/MS investigation, i.e., 3’,4’,5’,5,7,8-hexame-thoxy flavone, 6-gingerol, evodin, isosakuranetin-7-rutinoside, methyl ophiopogonanone A, narirutin, neohesperidin, ononin, sinensetin, and shogaol. This research shows that red ginger extract fermentation using kombucha culture can be an alternative technology to produce red ginger-based functional drinks with healthy organic acids, healthy polyphenols, and antioxidant activity

Effect of Ultrasonic-Assisted Enzymolysis on Protein, Phenolic Content, and Antioxidant Activity of Chlorella sp. Crude Extract

Chlorella sp. microalgae is a potential source of natural antioxidants and other bioactive compounds used in the food and pharmaceutical industries. Ultrasound pretreatments followed by enzymolysis are widely used to improve the functional properties of biological materials. This work aimed to investigate the effects of ultrasound pretreatments followed by bromelain hydrolysis on the proteins, phenolic content, and antioxidant activity of Chlorella sp. crude extract. The experimental design for the study involved two factors: ultrasound pretreatment time (0, 5, and 10 min) and bromelain hydrolysis time (0, 2, 4, and 6 hours). The protein was measured using Lowry assay while the total phenolic content was measured using a Folin–Ciocalteu assay. The highest protein content (7.09 ± 0.44 mg/mL) and phenolic concentrations (0.28 ± 0.01 ìg/mL) were obtained at 5 min ultrasound pretreatment and 6 hours enzymolysis. For antioxidant activity, 5 min ultrasound pretreatment followed by 4 hours of enzymolysis resulted in the highest DPPH (1,1-diphenyl-2-picrylhydrazyl radical) inhibitory activity (81.74%). Meanwhile, ultrasound pretreatment for 10 min followed by 6 hours of enzymolysis resulted in the highest ABTS (2,20 azinobis-(3-ethylbenzthiazoline-6-sulfonic acid) inhibitory activity (94.10%). This study showed that variation in ultrasound pretreatments followed by bromelain hydrolysis could be used to improve the protein content, phenolic content, and antioxidant activity of Chlorella sp. crude extract