Improving the taste of Ougan ( Citrus reticulate cv. Suavissima ) juice by slight fermentation with lactic acid bacteria

Effects of different lactic acid bacteria on phenolic profiles, antioxidant capacities, and volatile compounds in purple sweet potato juice

The effects of three strains of lactic acid bacteria (Lactobacillus plantarum, Lactobacillus rhamnosus, and Streptococcus thermophilus) on viable counts, physicochemical indicators, phenolic profiles, antioxidant capacities, and volatile compounds in purple sweet potato juice were investigated during fermentation. The results showed the viable count of three bacteria increased and exceeded 11 log CFU/mL after fermentation. At the end of fermentation, the purple sweet potato juice exhibited an increase in total phenolic and flavonoid content. In addition, lactic acid bacteria fermentation changed the phenolic profiles and enhanced antioxidant capacities. Moreover, Pearson's correlation analysis showed that DPPH, ABTS, and hydroxyl radical scavenging capacities were positively correlated with caffeic acid and vanillic acid content (p < 0.05). Furthermore, lactic acid bacteria fermentation improved the aroma complexity and sensory quality of purple sweet potato juice. In conclusion, this study provided useful information for the development of purple sweet potato juice fermented by lactic acid bacteria.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-05959-5.

Ougan juice debittering using ultrasound-aided enzymatic hydrolysis: Impacts on aroma and taste

The optimal sonication conditions (40 kHz, 80 W/L and 60 min) during Ougan juice debittering by Aspergillus niger koji extract were established. Enzymatic hydrolysis degrees of naringin and limonin were enhanced to 89.90% and 36.16%, and enzymatic hydrolysis time was shortened by 33%. Sonication significantly enhanced activities of α-l-rhamnosidases, β-glucosidases and limoninases from A. niger koji extract and facilitated break of CO bonds in naringin (p < 0.05). These accounted for the enhanced enzymatic hydrolysis degrees and velocities of bitter compounds. Meanwhile, sonication lowered 40%, 7% and 21%, 13%, 11%, 25% of bitter, sour tastes and green, citrus-like, floral, woody notes, but enhanced 18% and 15% of fruity and sweet notes, resulting in 38% and 33% increases in over-all taste and aroma scores. Lowered levels of bitter compounds, organic acids, green, citrus-like, floral, woody aroma compounds and enhanced levels of fruity, sweet aroma compounds caused by sonication accounted for the flavor improvements.

Biotransformation of two citrus flavanones by lactic acid bacteria in chemical defined medium

Microbial processes are being developed to transform flavonoid glycosides to varieties of metabolites with higher bioavailability. The aim of this study was to determine the metabolic activity and survival of five lactic acid bacteria (LAB) stains (L. rhamnosus LRa05, L. casei LC89, L. plantarum N13, L. acidophilus LA85, and L. brevis LB01) in two different citrus flavanone standards (hesperetin-7-O-rutinoside and naringenin-7-O-rutinoside). The enzymatic activity, metabolites, antioxidant activities, and α-glucosidase inhibition property in the two standards were also investigated before and after incubated with LAB. The medium contained standards permitted survival of the five LAB stains. All strains exhibited β-glucosidase activity. Of the five LAB strains tested, just L. plantarum N13 and L. brevis LB01 have the ability to metabolize hesperetin-7-O-rutinoside, only L. plantarum N13, L. acidophilus LA85, and L. brevis LB01 could metabolize naringenin-7-O-rutinoside, moreover, L. acidophilus LA85l was the strain with the highest biotransformation ratio of naringenin-7-O-rutinoside. L. acidophilus LA85 and L. plantarum N13 can degrade naringenin-7-O-rutinoside into naringenin. L. brevis LB01 can degrade hesperetin-7-O-rutinoside into hesperetin, 3-(4'-hydroxyphenyl)-2-propenoic acid, 3-(3'-hydroxy-4'-methoxyphenyl)hydracrylic acid, and 3-(4'-hydroxyphenyl)propionic acid. Incubation of L. acidophilus LA85 in naringenin-7-O-rutinoside solution supposed no apparent influence in the biological activities that tested. L. acidophilus LA85 may potentially contribute to the bioavailability of citrus flavanones, and to be applied as functional cultures to obtain more bioavailable and bioactive metabolites in food products or in the human gastrointestinal tract.