Bioactive compounds and antioxidant activities of the Korean lotus leaf (Nelumbo nucifera) condiment: volatile and nonvolatile metabolite profiling during fermentation

Abstract

Recent studies have shown that lotus (Nelumbo nucifera) leaf has various pharmacological effects. However, there have been no scientific investigations into these leaves as a fermented crude liquid. This study compared the in vitro antioxidant capacity of lotus leaf-fermented broth (LLFB) with that of 57°Brix sugar broth (SB) as a control over a period of 6 months based on 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, ferric ion reducing power, superoxide dismutase-like activity, tyrosinase inhibition and nitrite scavenging activity. The dominant species during fermentation process were Leuconostoc lactis and Saccharomyces cerevisiae for LLFB. A total of thirty-six metabolites such as alkaloids, fatty acids, organic acids, phenolics, sugar and sugar derivatives, ethyl esters and monoterpenoids differed between SB and LLFB using gas chromatography-mass spectrometry. Meanwhile, nine volatile compounds in LLFB contributed pleasant, slightly sweetish and fruity odour of condiment and sensory evaluation score of 4.06 AE 1.52 in the proportion of 1:9 LLFB/water.

Quantitative Analysis of Functional Components From Nelumbo Nucifera Root Fermented Broth with Antioxidant and Tyrosinase Inhibitory Effects

“…Similar findings were also observed by Hwang et al . (). These findings suggest that identification of phenolic compounds in fermented samples by GC‐MS analysis defines the basic fingerprint of fermented lotus root sugar syrup samples, but provides little information on minor and trace components, which often play a significant role in the delicate aromatic profile of fermented food samples.…”

“…Similar findings were previously observed with fermented lotus leaf sugar syrup, which showed high nitrite scavenging activity at pH 1.2 (Hwang et al . ). Sreevidya et al .…”

“…Similarly, Hwang et al . () reported that lotus leaf sugar syrup samples fermented for 15 days showed a flavonoid content of 92 µg QE/mL, which slightly increased until 180 days of fermentation. Hu et al .…”

“…Similarly, in a previous study, Hwang et al . () reported production of lotus leaf fermented beverage with increased phenolic content (501 μg GAE/mL) after 15 days of fermentation, suggesting its importance as a fermented functional food supplement with strong antioxidant potential. In addition, antioxidant activities and total phenolic content were previously shown to be positively correlated (Moktan et al .…”

“…GC‐MS conditions were followed as reported previously (Hwang et al . ). The relative proportions of the extract constituents were expressed as percentages by peak area normalization.…”