ABSTRACT
Lentilactobacillus buchneri isolated from Korean fermented plant foods produces ß-glucosidase, which can hydrolyze ginsenoside Rb1 from Panax ginseng to yield ginsenoside Rd. The aim of this study was to determine the mechanisms underlying the extracellular ß-glucosidase activity obtained from Lentilactobacillus buchneri URN103L. Among the 17 types of lactic acid bacteria showing positive ß-glucosidase activity in the esculin iron agar test, only URN103L was found to exhibit high hydrolytic activity on ginsenoside Rb1. The strain showed 99% homology with Lentilactobacillus buchneri NRRLB 30929, whereby it was named Lentilactobacillus buchneri URN103L. Supernatants of selected cultures with ß-glucosidase activity were examined for hydrolysis of the major ginsenoside Rb1 at 40 °C, pH 5.0. Furthermore, the ß-glucosidase activity of this strain showed a distinct ability to hydrolyze major ginsenoside Rb1 into minor ginsenosides Rd and Rg3. Lentilactobacillus buchneri URN103L showed higher leucine arylamidase, valine arylamidase, α-galactosidass, ß-galactosidase, and ß-glucosidase activities than any other strain. We conclude that ß-glucosidase from Lentilactobacillus buchneri URN103L can effectively hydrolyze ginsenoside Rb1 into Rd and Rg3. The converted ginsenoside can be used in functional foods, yogurts, beverage products, cosmetics, and other health products.
ABSTRACT
In this study, the physicochemical and sensory properties of Gouda cheese supplemented with microcapsules of chili pepper extract were evaluated. Microcapsules of pepper extract were prepared by coacervation technique using gum acacia-gelatin wall and chili pepper oil core. Changes in pH, lactic acid bacteria (LAB) population, and free amino acid (FAA) content after supplementation of Gouda cheese with chili pepper capsules were monitored during ripening. Texture and sensory characteristics of the Gouda cheese ripened for 6 months were evaluated. The supplementation of pepper extract microcapsules (0.5% or 1%, w/w) did not influence the pH values and LAB content of the Gouda cheese (p<0.05) during the ripening period. While the content of total FAA increased with the ripening process in all the cheese groups (p<0.05), no significant difference (p<0.05) in the content of total FAA was observed among the sample groups at each time point. The addition of pepper extract microcapsules (1%, w/w) to Gouda cheese significantly decreased hardness (p<0.05) and negatively affected sensory attributes in terms of taste and texture (p<0.05). The results demonstrated that supplementation with 0.5% pepper extract microcapsules could provide additional bioactive ingredients, along with maintenance of the quality of Gouda cheese.
ABSTRACT
BACKGROUND: An alkaline protease produced by the Serratia marcescens S3-R1 which inhabits in the Korean ginseng rhizosphere was investigated. The purposes of this study were to characterize and purify the bacterial enzyme by four different purification steps: precipitation of enzyme fraction by ammonium sulfate, loading the enzyme pellets on a DEAE-Sepharose anion-exchange chromatograph, separation of the fraction containing enzyme activity by fast protein liquid Mono Q chromatography and identification of the single-band fraction by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and then quantification of the single-band fraction by reverse-phase high-performance liquid chromatography. RESULTS: The molecular weight of the purified protease was estimated as 50 308 Da by matrix-assisted laser desorption ionization time-of-flight analysis. The N-terminal amino acid sequence of the protease was identified as Ala-Val-Thr-Ile-Glu-Asp-Ala-Val-Asp-Asp, and the enzyme belongs to the metalloprotease family. The optimal activities of the protease occurred at pH 7-9 and a temperature 40 °C. The ranges of pH and thermal stability of the enzyme were at 7-10 and 30-40 °C, respectively. CONCLUSION: The alkaline protease was successfully purified and characterized from the bacterium Serratia marcescens S3-R1, which has potential for industrial application, including milk protein hydrolysates.
