Page 145 - Zbornik_Konf_2019

https://doi.org/10.15414/2019.9788055220703

4 International Scientific Conference Abstracts Book
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PROPERTIES OF MICROBIAL α‐L‐RHAMNOSIDASES IMPROVING THE AROMA OF WINES
AND TASTE OF JUICES
Liudmyla Varbanets, Olena Gudzenko

D.K. Zabolotny Institute of Microbiology and Virology of the National Academy of Science of Ukraine,
Kyiv, Ukraine; E-mail: varbanets_imv@ukr.ner
α-L-Rhamnosidase [K.F. 3.2.1.40] is an enzyme that cleaves terminal non-restored L-
rhamnose residues present in both synthetic and natural glycosides, oligo-, polysaccharides,
various glycoconjugates, flavonoids derivatives – routine, neohesperidin, hesperidin, naringin,
quercitrin, saponins, ginsenosides; terpene glycosides – aziaticosides. Derhamnosilation of
natural glycosides can increase their biological activity and have a positive effect on the
quality of food products. Hydrolyzing terpene the glycoside enzyme promotes the release of
aromatic compounds that enhance the aroma of grape juices and wines, and the hydrolysis of
naringin, hesperidin, and routine improves the quality of citrus juices.
Earlier in the Institute of Microbiology and Virology of the National Academy of Sciences
of Ukraine, as a result of the screening of microorganisms – representatives of various
taxonomic groups from the Ukrainian collection of microorganisms, the producers of α-L-
rhamnosidases were selected: Eupenicillium erubescens, Cryptococcus albidus and Penicillium
tardum. From the investigated enzymes, C. albidus α-L-rhamnosidase was characterized by a
greater affinity for natural substrates than for synthetic ones.
Therefore, the purpose of the work was to study the possibility of practical use of C.
albidus α-L-rhamnosidase. The enzyme preparation was isolated from the supernatant of the
culture filtrate of the producer by precipitation with ammonium sulfate (up to 90 %
saturation) followed by chromatography on charged and neutral TSK gels (DEAE-Toyopearl
650-s and Toyopearl HW-60 Toya Soda Japan, respectively). To determine the activity and
specificity of the action of the enzyme, p-nitrophenyl derivatives of monosaccharides were
used. The ability to hydrolyze natural substrates was evaluated using methods of Davis and
high-performance liquid chromatography.
It was shown that the enzyme exhibits a narrow specificity with respect to glycon of
synthetic substrates, the hydrolyzes only p- nitrophenyl-α-L-rhamnopyranoside (Km 4.5 mM)
and p-nitrophenyl-β-D-glucopyranoside (Km 10 mM). The most effective C. albidus α-L-
rhamnosidase degraded naringin ("Sigma") (Km 0.77 mM), releasing prunin and naringenin.
Km for neohesperidin ("Sigma") was 3.3 mM. The effectiveness of the grapefruit and pomelo
juice hydrolysis was 94 and 98 % for 60 min (40 C, 2 units/ml). As a result of the treatment
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of green tea, mandarin and orange juice, a decrease in the content of routine, nary routine,
and hesperidin were observed, indicating the ability of α-L-rhamnosidase to cleave α-1,2- and
α-1,6-bound rhamnose from natural flavonoids. Thus, it was shown the effectiveness of the
use of C. albidus α-L-rhamnosidase for hydrolysis both commercial preparations of flavonoids
and citrus juices and green tea. The obtained results in perspective can be used in food
technologies for the production of juices, the improvement of the aroma of wines.
Keywords: α-L-rhamnosidase, Cryptococcus albidus, specificity, naringin, neohesperidin, routine,
flavonoids.

4 International Scientific Conference Agrobiodiversity Nutrition, Health and Quality of Human and Bees Life |145
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September 11–13, 2019