Traditional kombucha is a fermented black tea extract and sugar. Sweetened black tea (10% w/v) and wheatgrass juice (WGJ) were mixed in various ratios and used as fermentation substrate for enhancing phenolic compounds and antioxidant activity. Starter, comprising of yeast (Dekkera bruxellensis) and acetic acid bacteria (Gluconacetobacter rhaeticus and Gluconobacter roseus), was inoculated at 20% (v/v), and fermented statically at 29 ± 1°C for 12 days. The results showed that the total phenolic and flavonoid contents and antioxidant activity of the modified kombucha were higher than those of traditional preparations. All WGJ-blended kombucha preparations were characterized as having higher concentrations of various phenolic compounds such as gallic acid, catechin, caffeic acid, ferulic acid, rutin, and chlorogenic acid as compared to traditional ones. Addition of WGJ resulted in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging ability of kombucha being > 90%, while the oxygen radical absorbance capacity increased from 5.0 μmol trolox equivalents/mL to 12.8 μmol trolox equivalents/mL as the ratio of WGJ increased from 0% to 67% (v/v). The highest antioxidant activity was obtained using a 1:1 (v/v) black tea decoction to WGJ ratio and 3 days of fermentation, producing various types of phenolic acids. These results suggest that intake of fermented black tea enhanced with wheatgrass juice is advantageous over traditional kombucha formulas in terms of providing various complementary phenolics and might have more potential to reduce oxidative stress.
Glucosamine (GlcN) has been widely used to treat osteoarthritis. However, GlcN derived from crustacean shells has several drawbacks, and it is not vegan-friendly. Here, we produced GlcN from the biomass of Aspergillus oryzae NCH-42 and investigated the effects of environmental factors (e.g. carbon and nitrogen sources, temperature, and pH) on the GlcN production of the fungal biomass. The acidic stress resulted in significantly higher GlcN content in the cell wall of A. oryzae NCH-42. Moreover, the SEM examination revealed that the mycelial structure grown at pH 2.5 was thick and sturdy, compared to that at neutral pH conditions. The final yield of GlcN could be enhanced by up to 7.75-fold by cultivating at modified PDB with an initial pH of 2.5 at 30°C for 4 days. In this study, the GlcN content of A. oryzae biomass could reach up to 0.31 g/g biomass, indicating its high potentiality for GlcN production. Aumento de la producción de glucosamina a partir de Aspergillus oryzae NCH-42 mediante estrés ácido en fermentación sumergidaLa glucosamina (GlcN) se ha utilizado ampliamente para tratar la artrosis. Sin embargo, aquella que deriva de los caparazones de crustáceos presenta varios inconvenientes y no es apta para veganos. En el presente estudio produjimos GlcN a partir de la biomasa de Aspergillus oryzae NCH-42 e investigamos los efectos de los factores ambientales (por ejemplo, las fuentes de carbono y nitrógeno, la temperatura y el pH) en la producción de GlcN de la biomasa fúngica. El estrés ácido dio lugar a un contenido de GlcN significativamente mayor en la pared celular de A. oryzae NCH-42. Además, el examen SEM permitió comprobar que la estructura micelial cultivada a pH 2.5 era gruesa y robusta, en comparación con la cultivada en condiciones de pH neutro. El rendimiento final de GlcN se pudo multiplicar hasta por 7.75 al cultivarla en PDB (caldo de dextrosa de papa [patata]) modificado con un pH inicial de 2.5 a 30°C durante 4 días. En este estudio, el contenido de GlcN de la biomasa de A. oryzae alcanzó hasta 0.31 g/g de biomasa, lo que indica su alta potencialidad para producir GlcN.
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