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Naringin is a flavonoid in citrus fruits and contributes to the bitterness of extracted citrus fruit juices. Naringinase has potential to hydrolyse the naringin into tasteless compounds and, therefore, reduces the bitterness of citrus juices. Majority of studies focused on naringinase production from fungal sources. The present study aimed to use Paenibacillus stellifer RAMCM-44 for the production of naringinase by optimization of media constituents using Response Surface Methodology (RSM) at the shakeflask level. Five media components were taken as variables with different concentrations to determine the optimal concentrations of media components. The five variables included peptone (0.5-1%, w/v), yeast extract (0.4-0.8%, w/v), NaCl (0.5-1%, w/v), naringin (0.1-0.25%, w/v) and KH2PO4 (0.5-1%, w/v), while MgSO4 (0.05%, w/v), MnSO4 (0.001%, w/v) and initial pH (6.5±0.2) during shake-flask fermentation, media were kept constant. The experimental data was analysed (RSM) and optimal levels of peptone (0.75%), yeast extract (0.6%), NaCl (0.75%), naringin (0.17%) and KH2PO4 (0.75%) were determined. The experimental values of naringinase activity (8.55 IU/ml) and biomass (0.826 OD600) closely matched the predicted values. The criteria, including analysis of variance (ANOVA), R values, coefficient of variance and model significance were assessed. The R -value for naringinase production was found to be 0.9976, while the model F-value was 228.74 and the lack of fit F-value was 109.77 for naringinase activity, revealing the current study's significance. This is the first report on optimising media components and applying RSM for the production of naringinase by P. stellifer RAMCM-44, which could benefit studies involving scale-up. [ABSTRACT FROM AUTHOR]

Chemical amination of the enzyme was demonstrated to favor immobilization onto polydopamine (PDA)-coated magnetic nanoparticles (MNPs) for the first time, to the best of the author's knowledge. MNPs prepared via hydrothermal synthesis were coated with PDA for the immobilization of naringinase. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy showed that the MNPs were composed mainly of Fe3O4 with an average size of 38.9 nm, and coated with a 15.1 nm PDA layer. Although the specific activities of α-L-rhamnosidase (RAM) and β-D-glucosidase (GLU) of free naringinase decreased with amination, the immobilization yields of the aminated enzyme increased by more than 40% for RAM and more than 10-fold for GLU. The immobilization improved the enzyme's thermal stability (at 50 °C), reaching a half-life of 40.7 and 23.1 h for RAM and GLU activities, respectively. The biocatalyst was successfully used for the debittering of grapefruit juice, detecting a reduction in naringin of 56% after 24 h. These results demonstrate that the enzyme amination is an effective strategy to enhance the immobilization on a PDA coating and could be applied to other enzymes in order to obtain an easily recoverable biocatalyst using a simple immobilization methodology. [ABSTRACT FROM AUTHOR]

Bitterness in citrus juice is a common quality issue in the fruit-based beverage industry. Naringin, the dominant flavonoid responsible for bitterness in citrus fruit juice, can be mitigated by the enzyme naringinase. This study focuses on the isolation of novel naringinase-producing bacterium from mandarin orange peel, followed by the production and partial purification of naringinase. The bacterial strain exhibiting the highest enzyme production potential was identified as Bacillus megaterium AULS 1. The effects of carbon source (naringin) concentration, inducer (naringenin), pH, and temperature on naringinase production were investigated. Optimized conditions yielded a maximum naringinase production of 386.43 U mL–1. The produced enzyme was partially purified using ammonium sulfate precipitation and dialysis. The effects of pH, temperature, and metal ion concentration on the activity of the partially purified enzyme were evaluated, resulting in a highest activity of naringinase of 539.25 U mL–1 under optimized conditions. The debittering activity of the partially purified enzyme was 45.78 %. These findings demonstrate that Bacillus megaterium AULS 1 has the potential for naringinase production, and can be utilized for debittering citrus juices.

The article evaluates the impact of submerged culture parameters on growth and naringinase activity of Bacillus amyloliquefaciens D1 isolated from citrus gardens of North-East India. The study describes the morphological, biochemical and molecular characteristics of bacterial isolates, profiling of fatty acids, 16S rRNA gene analysis and homology. It examines the effects of incubation period, potential of hydrogen, temperature, carbon and nitrogen sources on growth and naringinase activity.

In this study, for the first time, we isolated a naringinase-producing strain from the Citrus aurantium L. var. amara Engl flower soil and identified it as Serratia marcescens C10. In order to improve naringinase activity for its industrial application, single-factor experiments were carried out to obtain the factors that greatly affect naringinase activity, and based on three factors and three levels of Box-Behnken Designs (BBD), response surface methodology (RSM) was used to optimize the culture conditions consisting of naringin concentration, inoculation size and fermentation time. Results showed that naringin concentration and fermentation time had a highly significant influence and significant influence on naringinase activity, respectively. Additionally, inoculation size and fermentation time had an interaction with naringinase activity. The optimized conditions were a naringin concentration of 0.09 mg/mL, an inoculation size of 5.5%, and a fermentation time of 60 h. Under optimal culture conditions, the experiment naringinase activity was 30.81 U/mL, which was close to the predicted theoretical value of 31.23 U/mL. The optimized naringinase was used to remove naringin in grapefruit juice, and the removal rate was 88.85% under optimal reaction conditions. [ABSTRACT FROM AUTHOR]

The application of Neurospora sp., a fungus that commonly thrives on complex agricultural and plant wastes, has proven successful in utilizing citrus peel waste as a source of naringin. A UV-Vis spectrophotometric method proved the biotransformation of naringin, with an absorption maximum (λmax) observed at 310 nm for the biotransformed product, naringenin (NAR). Further verification of the conversion of naringin was provided through thin layer chromatography (TLC). The Neurospora crassa mediated biotransformation of naringin to NAR was utilized for the rapid (within 5 min) synthesis of silver (Ag) and gold (Au) nanoconjugates using sunlight to accelerate the reaction. The synthesized NAR-nano Ag and NAR-nano Au conjugates exhibited monodispersed spherical and spherical as well as polygonal shaped particles, respectively. Both of the nanoconjugates showed average particle sizes of less than 90 nm from TEM analysis. The NAR-Ag and NAR-Au nanoconjugates displayed potential enhancement of the antimicrobial activities, including antibacterial and nematicidal properties over either standalone NAR or Ag or Au NPs. This study reveals the potential of naringinase-producing Neurospora sp. for transforming naringin into NAR. Additionally, the resulting NAR-Ag and NAR-Au nanoconjugates showed promise as sustainable antibiotics and biochemical nematicides. [ABSTRACT FROM AUTHOR]

Bitterness in citrus juice is a common quality issue in the fruit-based beverage industry. Naringin, the dominant flavonoid responsible for bitterness in citrus fruit juice, can be mitigated by the enzyme naringinase. This study focuses on the isolation of novel naringinase-producing bacterium from mandarin orange peel, followed by the production and partial purification of naringinase. The bacterial strain exhibiting the highest enzyme production potential was identified as Bacillus megaterium AULS 1. The effects of carbon source (naringin) concentration, inducer (naringenin), pH, and temperature on naringinase production were investigated. Optimized conditions yielded a maximum naringinase production of 386.43 U mL-1. The produced enzyme was partially purified using ammonium sulfate precipitation and dialysis. The effects of pH, temperature, and metal ion concentration on the activity of the partially purified enzyme were evaluated, resulting in a highest activity of naringinase of 539.25 U mL-1 under optimized conditions. The debittering activity of the partially purified enzyme was 45.78 %. These findings demonstrate that Bacillus megaterium AULS 1 has the potential for naringinase production, and can be utilized for debittering citrus juices. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan University of Technology Natural Science Edition is the property of Henan University of Technology Journal Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Yuzu (Citrus junos Sieb.) is a peel-edible fruit with a pleasant aroma, but its bitter taste can impact consumer appeal. In this study, an efficient enzymatic method reduced bitterness in green yuzu powder (GYP). Cellulase KN and naringinase from Aspergillus oryzae NYO-2 significantly decreased naringin and neohesperidin content by over 87 %, while increasing total dietary fiber and soluble dietary fiber by up to 10 % and 51 %, respectively. Insoluble dietary fiber decreased by up to 22 %. Cellulose, hemicellulose, lignin, and pectin contents in enzyme-treated YP decreased by 1.15–2.00-fold, respectively. Enzyme-treated GYP exhibited improved physicochemical properties, including enhanced solubility, oil-holding capacity, and water swelling capacities. 3T3-L1 cells treated with cellulase-treated GYP and naringinase-treated GYP showed lower lipid accumulation and higher lipolysis capability than GYP, along with decreased fatty acid synthase contents. These findings suggest that enzyme-treated GYP holds potential as a functional ingredient in the food industry.

The development of resistance, instability and high doses are some drawbacks of biologically active natural products. Modification of natural compounds to make it broad spectrum is the standard approach in drug design. This paper sets to modify the naringenin by silver nanoparticle conjugation to enhance its already reported pharmacological activities. The naringenin-nano silver conjugate was synthesized by one-step green synthesis, that is, sunlight exposure confirmed by UV spectroscopy. The biosynthesized naringenin-nanosilver conjugate was tested for antiacanthamoebal and antimicrobial potential. The antibacterial potential was increased by 5.8–6.14 fold against Gram positive bacteria, that is, S. aureus and Bacillus subtilis and 4.5–13.6 fold against Gram negative bacteria, that is, Escherichia coli and Pseudomonas aeruginosa. The standard naringenin-nanosilver conjugate significantly reduced the LC50 values against the Acanthamoeba cells, by, 66% and 36%, as compared to substrate naringin and standard naringenin respectively while biotransformed naringinin-nanosilver conjugate reduced LC50 by 50.56%, compared with biotransformed naringenin. Hence modification of natural product as nanoconjugate is the best practice for improvement as an effective drug. [ABSTRACT FROM AUTHOR]

Diosmin (DSN) is found mainly in citrus fruits, and has potent antioxidant effects. This study aimed to evaluate pharmacokinetics of diosmetin-7-glucoside-γ-cyclodextrin (DIOSG-CD) inclusion complex. The area under the curve values from AUC 0 - 24 of DIOSG-CD, prepared by reacting DSN and naringinase with γ -CD, were approximately 800-fold higher than those of DSN following their administration in Sprague-Dawley rats. [ABSTRACT FROM AUTHOR]

This study aimed to develop a method of naringinase biosynthesis by Aspergillus niger KMS on an optimized culture medium. The concentration of the six medium components in shake flasks was optimized by the Box and Wilson factor gradient method. Naringinase's substrate, naringin, powdered albedo, flavedo, and red grapefruit segment membranes were used to stimulate naringinase biosynthesis. Rhamnose was chosen as the carbon source, while the nitrogen source was yeast extract and sodium nitrate. Naringinase biosynthesis was most favorable in the culture medium with the following composition (g 100 mL): 3.332—NaNO3; 3.427—yeast extract; 0.184—KH2PO4; 0.855—red grapefruit albedo; 0.168—naringin; 2.789—rhamnose. The obtained Aspergillus niger KMS culture fluid was concentrated, thereby precipitating the protein. As a result, a naringinase preparation with high activity, equal to 816 µmol × min−1 × g−1, was obtained. [ABSTRACT FROM AUTHOR]

Naringin and limonin are the two main bitter compounds of citrus products such as grapefruit juice. The aim of this investigation was to evaluate the reduction in both bitter components simultaneously using a combined biochemical and physical approach. The proposed strategy was based on the use of heterofunctional supports with glyoxyl groups that allow for the covalent immobilization of naringinase, which hydrolyses naringin and alkyl groups that allow for the adsorption of limonin. The supports were butyl-glyoxyl agarose (BGA) and octyl-glyoxyl agarose (OGA), which were characterized in terms of aldehyde group quantification and FTIR analysis. The optimal pH and temperature of free and immobilized enzymes were assessed. The maximum enzyme loading capacity of supports was analyzed. Debittering of grapefruit juice was evaluated using soluble enzyme, enzyme-free supports, and immobilized catalysts. Enzyme immobilized in BGA reduced naringin and limonin concentrations by 54 and 100%, respectively, while the use of catalyst immobilized in OGA allowed a reduction of 74 and 76%, respectively, obtaining a final concentration of both bitter components under their detection threshold. The use of OGA biocatalyst presented better results than when soluble enzyme or enzyme-free support was utilized. Biocatalyst was successfully applied in juice debittering in five repeated batches. [ABSTRACT FROM AUTHOR]

To improve the naringinase production of Aspergillus tubingensis UA13, shorten the fermentation period, and verify its industrial application value, naringinase production conditions were optimized, and 5 L scale-up study in stirred tank bioreactor was carried out. Parameters, including carbon, nitrogen sources and inducer, optimal seed age, inoculum amount, temperature and pH, were adjusted and optimized in shaking flask. Keeping pH at the optimal value 6 in bioreactor, dissolved oxygen was monitored during the fermentation and the optimal stirring rate was investigated. In 5 L scale-up study, the highest naringinase activity was 72.62 U/mL, which was 1.75 times higher than that (41.52 U/mL) in shaking flask and the fermentation period was shortened by 24 h. [ABSTRACT FROM AUTHOR]

Citrus fruits are consumed either as whole fruits or as juice after processing. Processing of fruits yields a significant number of by-products in the form of pulp, peel and seeds, which are often discarded and major cause of environmental concern. Bitterness in the waste residue of citrus products is one of the leading hindrance in its valorization and supplementation in other food products. Aim of this study was to reduce the bitterness of Citrus reticulata (kinnow) pomace using enzymatic method and its supplementation in production of nutritionally rich pasta. Under optimized conditions (1U/mg enzyme naringinase concentration, temperature 50 °C, at pH 4.5 and treatment time 4 h), the maximum reduction (65.95%) of naringin (bitterness causing compound) was observed coupled with increase (60.13%) in naringenin (non-bitter compound). The debittered kinnow pomace has been further characterized for physio-chemical changes and morphological changes before and after treatment. The debittered kinnow pomace was then supplemented for the preparation of antioxidant and nutrient enriched pasta. [ABSTRACT FROM AUTHOR]

Naringinase was mainly obtained by microbial fermentation, and mutagenesis was a major way for obtaining excellent mutants. The aim of this study was to screen out a high naringinase yielding mutant to enhance the potential application value of its industrialization and compare the effects of different mutagenic methods on the enzyme activity of the strain. A novel producing naringinase strain, Aspergillus tubingensis MN589840, was isolated from mildewed pomelo peel, later subjected to mutagenesis including UV, ARTP and UV‐ARTP. After five rounds iterative mutagenesis, the mutants U1, A6 and UA13 were screened out with 1448·49, 1848·71, 2475·16 U mg−1 enzyme activity, the naringinase productivity raised by 79·08, 123·56 and 206%, respectively. In addition, the naringinase activity of three mutants rose after each round of iterative mutagenesis. These results indicated that the mutagenesis efficiency of UV‐ARTP was higher than that of single ARTP, and both are better than UV. In summary, the iterative UV‐ARTP mutagenesis is an effective strategy for screening high naringinase‐producing strains. [ABSTRACT FROM AUTHOR]

In the present work, enzymes pectinase and naringinase were simultaneously co-immobilized on an eco-friendly chitosan coated magnetic nanoparticles (chitosanMNPs) by cross-linking using chitosan as a macro-molecular cross-linker. The maximum activity recovery of both enzymes in the co-immobilized form was obtained at chitosanMNPs to enzymes ratio of 1:3, 3% cross-linker concentration and 150 min cross-linking time. The synthesized MNPs before and after co-immobilization were characterized using different techniques. The prepared biocatalyst was found spherical with an average size below 200 nm and showed supermagnetic property with saturation magnetization of 38.28 emu/g. The optimum pH and temperature of both enzymes in co-immobilized form was found at 5.5 and 65 °C. The prepared biocatalyst exhibited an improved thermal stability with 1.8-fold increase in the half-life. The secondary structural analysis revealed that, prepared co-immobilized biocatalyst undergone changes in the conformational and structural rigidity due to macro-molecular cross-linker. The co-immobilized biocatalysts were evaluated for one pot clarification and debittering of grapefruit juice and found ~52% reduction in turbidity and ~85% reduction in the naringin content. The co-immobilized enzymes were recycled up to 7th cycle and can be easily stored at room temperature for 30 days retaining up to 64% and 86% residual activities respectively. • An eco-friendly magnetic support using chitosan as coating agent was synthesized. • Pectinase and naringinase were simultaneously co-immobilized on chitosanMNPs. • Oxidized chitosan was used as cross-linking agent to bind enzymes and chitosanMNPs. • Co-immobilized enzymes@chitosanMNPs was thermally stable. • One step clarification and debittering of grapefruit juice was studied. [ABSTRACT FROM AUTHOR]

• Content of poorly soluble naringin substrate was increased by resin adsorption. • Resin adsorption improve naringin biotransformation efficiency. • Liter-scale hydrolysis of naringin at high concentration was performed. • The enzymatic product naringenin could be purified from the resin. Naringenin, a natural plant flavonoid found in citrus fruits, has been reported to exhibit a wide range of pharmacological functions, including anticancer, antioxidant, antiatherogenic, antithrombotic, and vasodilator activities. Naringenin can be produced from the naringinase (NGase)-catalyzed enzymatic hydrolysis of naringin. However, the poor solubility of naringin in aqueous systems considerably limits the efficiency of naringenin biocatalysis. In this work, a novel substrate adsorption system was proposed for naringin adsorption to increase the efficiency of naringin hydrolysis and naringenin production. Three Amberlite macroporous resins, namely, XAD-4, XAD-7HP and XAD-16, were investigated for their naringin adsorption capacities and effects on NGase hydrolysis. Results indicated that the physical properties of the resins played a critical role in naringin adsorption and naringenin enzymatic synthesis. Naringin hydrolysis was carried out using free and adsorbed substrates. The substrate adsorption strategy could increase the catalytic efficiency at a high naringin concentration. In addition, the reaction conditions for enzymatic naringenin synthesis were optimized, and naringenin was prepared at a liter scale with a high substrate concentration. These results suggested that substrate adsorption is a promising strategy to increase the enzymatic hydrolysis efficiency of naringenin in aqueous systems. [ABSTRACT FROM AUTHOR]

Naringinase (NGase) is a multi-compound enzyme with the subunits of α-L-rhamnosidase (Rha) and β-D-glucosidase (BGL). The biotransformation of naringin into the more valuable naringenin was impeded by the uncoordinated activity and instability of natural naringinases. In this study, the efficient artificial fusion naringinases of Rha from Spirochaeta thermophila (StRha) and BGL from Pyrococcus furiosus (PfBGL) were constructed and utilized in biosynthesis of naringenin. Fusion naringinases StRha-PfBGL (DL-NGase), StRha-(GGGGS)-PfBGL (FL-NGase) and StRha-(EAAAK)-PfBGL (RL-NGase) were obtained by fusing StRha and PfBGL through direct fusion or mediated by peptide linkers. DL-NGase showed more coordinated activity and better thermostability than FL-NGase and RL-NGase. The optimal temperature of StRha and PfBGL of DL-NGase was above 65 °C, and both retained above 75% of the initial activities at 55 °C for 2 h. In addition, fusion naringinases exhibited better catalytic performance than the mixed free enzyme systems, and the catalytic efficiency of DL-NGase was increased by 49.8%. Furthermore, DL-NGase whole-cell catalyst was applied for the high-efficient biosynthesis of naringenin, and the final naringenin yield was 13.5 mg/mL with a time-space yield of 2.25 mg/mL/h. These results demonstrate the great potential of artificial fusion naringinases for the efficient bioconversion of naringin to naringenin. [Display omitted] • Artificial fusion naringinases were successfully constructed for the first time. • Artificial fusion naringinases show better operating temperature and thermostability. • Artificial fusion naringinases improve the biosynthesis efficiency of naringenin. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian Polytechnic University is the property of Journal of Dalian Polytechnic University Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Compound K is a type of protopanaxadiol-type ginsenosides (PPDs) that has strong bioactivities due to fewer glycosyls. However, compound K is not present in raw and unprocessed ginseng. Some PPDs have the same structure with gypenosides, and could be obtained from Gynostemma pentaphyllum. The enzymolysis of PPD-type gypenosides of G. pentaphyllum by naringinase has been reported for the first time in this research. In addition, isolation and identification of enzymolysis end product, and the optimization of enzymolysis parameters were investigated. The results showed that compound K was produced from the enzymolysis of PPD-type gypenosides by naringinase, and could be isolated and purificated by HP-20 macroporous resin and C-18 column chromatography. The optimum enzymolysis conditions determined by the response surface methodology (RSM) are pH 4.1, 50 °C, and 71 h, with a yield of 65.44 ± 4.52% for compound K. These results demonstrated that enzymolysis could be a promising method for producing compound K from the biotransformation of PPD-type gypenosides of G. pentaphyllum. • Protopanaxadiol-type gypenosides were isolated from total gypenosides. • Compound K was prepared from protopanaxadiol-type gypenosides by naringinase. • The optimum enzymolysis conditions were pH 4.1, 50 °C, and 71 h. • Enzymatic conversion was an easier and cheaper way to obtain compound K. [ABSTRACT FROM AUTHOR]

Characteristics of naringinase nano-encapsulated forms on different carrier materials (chitosan and alginate polymers) were investigated in this study. Screening of twelve fungal isolates for naringinase production indicated that Trichoderma longibrachiatum was the most promising. Grapefruit rind was used as a substrate containing naringin for naringinase production. TEM micrographs showed that chitosan nano-capsules were applied for the production of morphologically homogeneous enzymatic nano-particles with high enzyme encapsulation efficiency, small asymmetric sizes (from 15.09 to 27.07 nm with the mean of 21.8 nm) and rough surfaces compared to nano-encapsulated naringinase in alginate which showed nano-particle size (from 33.37 to 51.01 nm with the mean of 43.03 nm). It was revealed that the highest naringinase activity was found in case of chitosan nano-capsule naringinase compared to alginate nano-capsule one. Thermogram analysis (TGA) showed that the free enzyme loses about 92% of its weight at approximately 110°C, while the nano-encapsulated ones show more stability at higher temperatures. Conclusively, the nano-capsulation process improves the kinetics and operational stability so could be useful as a debittering agent for various thermal processing applications in citrus juices industries which makes the fruit juice more acceptable and cost-effective to the consumer. [ABSTRACT FROM AUTHOR]

Naringinase has high industrial importance, and the progress in naringinase research is still quite slow. The unavailability of an effective, simple screening method, which will be applicable to different microorganisms such as bacteria, fungi, and actinomycetes, is one of the main reasons for this gap. Therefore, a simple plate assay was developed for effective screening of microorganisms for naringinase by exposing to iodine vapors. This plate assay will fill the technological void for simple screening method and will lead to screen more potent industrially important naringinase‐producing microorganisms. [ABSTRACT FROM AUTHOR]

Naringinase is an enzymatic complex used in the deglycosylation of compounds with a high application potential in the food and pharmaceutical industries. The aim of the study was to immobilize naringinase from Aspergillus niger KMS on a magnetic carrier obtained on the basis of carob gum activated by polyethyleneimine. Response surface methodology was used to optimize naringinase immobilization taking into account the following factors: pH, immobilization time, initial concentration of naringinase and immobilization temperature. The adsorption of the enzyme on a magnetic carrier was a reversible process. The binding force of naringinase was increased by crosslinking the enzyme with the carrier using dextran aldehyde. The crosslinked enzyme had better stability in an acidic environment and at a higher temperature compared to the free form. The immobilization and stabilization of naringinase by dextran aldehyde on the magnetic polysaccharide carrier lowered the activation energy, thus increasing the catalytic capacity of the investigated enzyme and increasing the activation energy of the thermal deactivation process, which confirms higher stability of the immobilized enzyme in comparison with free naringinase. The preparation of crosslinked naringinase retained over 80% of its initial activity after 10 runs of naringin hydrolysis from fresh and model grapefruit juice.

This study evaluated the effects of high hydrostatic pressure (HHP) and thermal pasteurization (TP) on microbial counts, physicochemical properties, antioxidant characteristics, naringin and naringenin contents, and naringinase activity of grapefruit juice during 21 days cold storage period. Results showed that HHP and TP significantly decreased the total microbial, coliform, and yeast counts. No significant differences between HHP-treated grapefruit juice (600 MPa/5 min) and untreated fruit juice with respect to physicochemical properties such as total titratable acidity, pH, and total soluble solids was observed after 21 days of storage. Although HHP affected the colour and antioxidant characteristics of grapefruit juice, the extent of effect was significantly lower than that for TP-treated fruit juice. This demonstrated that HHP could better maintain the original flavour and quality of grapefruit juice compared to TP. In addition, 92% naringinase activity was maintained in HHP-600 group on Day 21, which increased the degradation of bitter naringin into non-bitter naringenin during the cold storage of grapefruit juice. In summary, HHP can simultaneously maintain the microbiological safety of grapefruit juice along with its original quality characteristics. HHP can effectively extend the storage period and safety during cold chain transport, and hence highly applicable in the grapefruit juice industry. [ABSTRACT FROM AUTHOR]

Copyright of Research Papers of the Wroclaw University of Economics / Prace Naukowe Uniwersytetu Ekonomicznego we Wroclawiu is the property of Uniwersytet Ekonomiczny we Wroclawiu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gypenoside XLVI (gyp XLVI) is one of the major dammarane-type triterpenoid saponins from Gynostamma pentaphallum with glucosyls at C-3 and C-20 positions, which may constrain its bioactivities. The enzymatic conversion of gyp XLVI by naringinase, and the cytotoxicity of enzymolysis product on SMMC7721 and Bel7402 hepatoma cells were investigated. The results showed that gynosaponin TN-1 (gyp TN-1) was produced from the enzymatic conversion of gyp XLVI by naringinase. The optimum enzymolysis conditions were pH 4.2, 47.3 °C, and 16 h, with a yield of 73.44 ± 6.52% for gyp TN-1. In addition, gyp TN-1 exhibited higher inhibitory activities on SMMC7721 and Bel7402 hepatoma cells than gyp XLVI. Results from methyl thiazolyl tetrazolium (MTT) assay and acridine orange (AO)/ethidium bromide (EB) double staining were highly consistent. These results demonstrated that enzymatic conversion could be a promising method for producing gyp TN-1 from the biotransformation of gyp XLVI and the preparation of gyp TN-1 might provide a reference for the acquisition of novel anticancer drugs. [ABSTRACT FROM AUTHOR]

Naringin is a flavonoid naturally present in citrus fruits. It is present in orange, grapefruit, lemon and other fruits of citrus family. Naringin is the major cause of bitterness in citrus fruit juices. This flavonoid may cause interference during the citrus fruit juice processing. Naringinase (E.C.3.2.1.40) is an enzyme which catalyzes the hydrolysis of naringin into prunin and then into naringenin, which is non-bitter and tasteless. Naringinase is produced by many microorganisms but the commercial production of this microbial enzyme is still the area of interest. Naringinase is chiefly produced by various fungal strains and it has been reported for elimination of bitter flavour (due to naringin) in citrus fruit juice. Few bacterial sources have also been reported for naringinase. Besides removal of bitterness, naringainase has potent application in enhancement of aroma in wine making. This review focuses over microbial sources, production and applications of naringinase in food industries. [ABSTRACT FROM AUTHOR]

Naringinase which was extracted from the fermented broth of Cryptococcus albidus was purified about 42-folds with yield 0.7% by sulfate fractionation and chromatography on Toyopearl HW-60, Fractogel DEAE-650-s, and Sepharose 6B columns. Molecular weight of protein determined by gel filtration and SDS-PAGE was 50 kDa. Naringinase of C. albidus includes high content of the dicarbonic and hydrophobic amino acids. Enzyme contains also carbohydrate component, represented by mannose, galactose, rhamnose, ribose, arabinose, xylose, and glucose. The enzyme was optimally active at pH 5.0 and 60 °C. Naringinase was found to exhibit specificity towards p-nitrophenyl-α-L-rhamnose, p-nitrophenyl-β-D-glucose, naringin, and neohesperidin. Its Km towards naringin was 0.77 mM and the Vmax was 36 U/mg. Naringinase was inhibited by high concentrations of reaction product—L-rhamnose. Enzyme revealed stability to 20% ethanol and 500 mM glucose in the reaction mixture that makes it possible to forecast its practical use in the food industry in the production of juices and wines. [ABSTRACT FROM AUTHOR]

The bitterness of citrus juices is a major obstacle to their industrial acceptance. Bitterness can be reduced using the naringinase enzyme. This study investigated two approaches for producing and purifying naringinase. Bacillus subtilis strain Bsnari was isolated from the Red Sea with accession number OQ576096 and had the highest naringinase productivity (7.09 ± 0.09 U/ml) using sucrose (1.5%) as carbon source, 0.6% w/v of citrus peel powder and 1% w/v of soy bean meal at pH 7.0 and 37 °C. Box-Behnken design has been successfully used for statistical modeling of naringinase production by Bacillus subtilis. Naringinase was partially purified using ammonium sulfate and gel filtration, resulting in a specific activity of 215.106 U/mg, a purification fold of 8.95, and a molecular weight of 73 KDa. Enzymatic hydrolysis reduced bitterness by around 33–36%, with optimal debittering after 4 h at 40–50 °C. A new method for processing citrus juice debittering was proposed using α - l -rhamnosidase and β - d -glucosidase encoded by the genes rhaA and bglA, respectively. The protein structures of β - l -rhamnosidase and β - d -glucosidase were also investigated. The topology of the 3D structure of α - l -rhamnosidase and β - d -glucosidase proteins of Bacillus sp. Predicted and aligned against other bacterial species. These findings provide insights into efficient naringinase production and purification for use in various applications, with implications for commercial production in food and pharmaceutical industries. • Naringinase has been successfully produced, partially purified and applied for reduction of food bitterness. • The study used Bacillus subtilis Strain Bsnari isolated from the Red Sea as a novel source for naringinase production. • Naringinase production Bacillus subtilis Strain Bsnari has been statistically modeled and optimized. • A new method for processing citrus juice debittering was proposed using α -L-rhamnosidase and β -D-glucosidase. [ABSTRACT FROM AUTHOR]

Naringinase is an enzyme complex which exhibits α-l-rhamnosidase and β-d-glucosidase activity. This enzymatic complex catalyzes the hydrolysis of naringin (4′,5,7-trihydroxy flavanone 7-rhamnoglucoside), the main bittering component in grapefruit. Reduction of the level of this substance during the processing of juice has been the focus of many studies. The aim of the study was the immobilization of naringinase on chitosan microspheres activated with glutaraldehyde and, finally, the use of such immobilized enzyme for debittering grapefruit juice. The effect of naringinase concentration and characterization of the immobilized enzyme compared to the soluble enzyme were investigated. The maximum activity was observed at optimum pH 4.0 for both free and immobilized naringinase. However, the optimum temperature was shifted from 70 to 40 °C upon immobilization. The KM value of the immobilized naringinase was higher than that of soluble naringinase. The immobilization did not change the thermal stability of the enzyme. The immobilized naringinase had good operational stability. This preparation retained 88.1 ± 2.8% of its initial activity after ten runs of naringin hydrolysis from fresh grapefruit juice. The results indicate that naringinase immobilized on chitosan has potential applicability for debittering and improving the sensory properties of grapefruit juices.

Naringinase plays a rather important role in reducing the bitterness of juice by hydrolyzing naringin. A novel extracellular naringinase was purified from Aspergillus oryzae 11250 cultured in the presence of orange peel. A 26.78-fold purification rate was achieved by salt-induced precipitation, followed by anion-exchange and gel filtration chromatography with 32% recovery and specific activity of 2194.62 units per mg protein (U/mg). The optimum pH and temperature for naringinase activity were 5.0 and 45 °C, respectively. This enzyme was stable at 30 °C for 5 h. The K m and V max of naringinase toward naringin determined by Lineweaver-Burk method were 1.60 ± 0.13 mM and 126.21 ± 5.52 μmol/(min mg), respectively. The enzyme activity was inhibited completely by Ag + at 10 mM. Naringinase is capable of hydrolyzing naringin, neohesperidin, and some other glycosides. A supplement of 6 U/mL of this naringinase in citrus juice sufficiently removed naringin to relieve the bitterness of citrus juice. These properties make the enzyme an ideal candidate for commercial application in the debitterization of orange juice. [ABSTRACT FROM AUTHOR]

The enzymatic deglycosylation of the plant flavonoid rutin (quercetin-3- O- (6- O -α- l -rhamnopyranosyl-β- d -glucopyranoside) is usually assessed by means of high performance liquid chromatography (HPLC). We have developed a spectrophotometric method for the quantification of the released quercetin. After the enzymatic reaction, quercetin is extracted with ethyl acetate, and subsequently oxidized under basic conditions. The absorbance of quercetin autooxidation products at 320 nm was correlated with the quercetin concentration by linear regression (molar extinction coefficient 23.2 (±0.3) × 10 3 M −1 cm −1 ). With this method, rutin-deglycosylation activity in buckwheat flour and a commercial naringinase was measured, and showed no significant differences with the results obtained by HPLC. The convenience of this method resides on the enzymatic activity quantification using the natural substrate by UV–visible spectrometry. Moreover, the simplicity and speed of analysis allows its application for a large number of samples. [ABSTRACT FROM AUTHOR]

Electrospinning is a facile method to fabricate nanofibers, in terms of their high specific surface area and porous structure. Electrospun nanofibrous mats are excellent candidates for immobilization of enzymes. In this study, a simple route based on electrospinning and layer-by-layer (LBL) self-assembly processes has been developed to prepared naringinase/alginate multilayer coated electrospun cellulose acetate nanofibers. The content of immobilized naringinase could be tuned by adjusting the number of multilayers. XPS results indicated that naringinase was successfully immobilized on cellulose acetate nanofibers. SEM images showed the nanofibers maintain their sharp but became rougher after multilayer coating. Besides, the surface area of electrospun cellulose acetate nanofibers decreased and mesopores reduced. The major bitter components of grapefruit juice are naringin and limonin, naringin could be slightly removed by hydrolysis with naringinase and limonin might be removed by adsorption with cellulose acetate nanofibers. [ABSTRACT FROM AUTHOR]

Brazil is the world's largest producer of orange and concentrated juice for export. Concentrated juice with high levels of naringin has excessive bitterness, which reduces the quality and value on the market. The debittering can be obtained by using naringinase, an enzymatic complex that degrades naringin. This study reports the production of naringinase by Aspergillus niger 426 utilizing both sugar cane molasses as carbon source and yeast extract as nitrogen source. Naringin was used as inducer. Five nitrogen sources were studied and yeast extract was found as the best one as 225.6 mU/mL of naringinase activity at 120 hours of fermentation was achivied. For optimization of naringinase production it was applied response-surface methodology, with 22 incomplete factorial design. An activity value of 354.26 mU/mL of naringinase was achivied when as independent variables yeast extract (14.0g/L) and naringin (0.2g/L) were used. When applied ultrasound waves at 20 kHz of intensity for 2 minutes in the fermented broth, the activity reached the highest value of 473.6 mU/mL. Thus, naringinase, this enzyme of great potential for biotechnological applications, has its production increased by using statistical design and ultrasound.O Brasil é o maior produtor mundial de laranja e de suco concentrado destinado à exportação. Sucos cítricos concentrados para exportação com níveis elevados de naringina são excessivamente amargos, o que reduz a qualidade e o valor comercial do produto. A redução do amargor pode ser obtida pela naringinase, um complexo enzimático que degrada a naringina. Neste trabalho Aspergillus niger 426 foi usado como produtor de naringinase utilizando matérias-prima da agroindústria, melaço como fonte de carbono e extrato de levedura como fonte de nitrogênio. Naringina foi usada como indutor. Dentre as cinco fontes de nitrogênio pesquisadas, extrato de levedura apresentou o melhor resultado de 225,6 mU/mL de naringinase em 120 horas de cultivo. Para otimização da produção de naringinase, foi aplicada a metodologia de superfície de resposta, com planejamento fatorial incompleto 22, obtendo 354,26 mU/mL de atividade de naringinase, tendo como variáveis independentes o extrato de levedura (14,0g/L) e naringina (0,2g/L). Quando aplicadas ondas de ultrassom com intensidade de 20 kHz por 2 minutos na cultura, a atividade de naringinase atingiu o valor máximo de 473,6 mU/mL. Assim, a naringinase, enzima de grande potencial de aplicação biotecnológica, teve a produção aumentada pelo uso do planejamento estatístico e ultrassom.

Naringinase bioprocess based onBacillus methylotrophicuswas successfully scaled up based on constant oxygen transfer rate (OTR) as the scale-up criterion from 5-L bioreactor to 20-L bioreactor. OTR was measured in 5 and 20-L bioreactor under various operating conditions using dynamic method. The operating conditions, where complete dispersion was observed were identified. The highest OTR of 0.035 and 0.04 mMol/L/s was observed in 5 and 20-L bioreactor, respectively. Critical dissolved oxygen concentration of novel isolated strainB. methylotrophicuswas found to be 20% of oxygen saturation in optimized medium. TheB. methylotrophicuscells grown on sucrose had maximum oxygen uptake rate of 0.14 mMol/L/s in optimized growth medium. The cells produced the maximum naringinase activity of 751 and 778 U/L at 34 hr in 5 and 20-L bioreactors, respectively. The maximum specific growth rate of about 0.178/hr was observed at both the scales of operations. The maximum naringinase yield of 160 and 164 U/g biomass was observed in 5 and 20-L bioreactors, respectively. The growth and production profiles at both scales were similar indicating successful scale-up strategy forB. methylotrophicusculture. [ABSTRACT FROM PUBLISHER]

An intracellular naringinase from Bacillus amyloliquefaciens 11568 isolated from soil was purified, identified, and characterized. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the purified enzyme gave a single protein band corresponding to a molecular mass of 32 kDa. The optimum pH and temperature for naringinase and its α - l -rhamnosidase and β - d -glucosidase activities were pH 7.5 and 45 °C, respectively. The enzymes were stable below 45 °C between pH 3.5 and 8.5. The K m and the V max of the isolated naringinase were 0.95 mmol/L and 3847.3 mmol/(L·min), respectively. The isolated naringinase was capable of hydrolyzing naringin, neohesperidin, and other glycosides. Additionally, a concentration of 4 U/mL of the enzyme in citrus juice was sufficient to remove the naringin and alleviate the bitterness of the juice. These results provide an in-depth insight into the structure of the naringinase and the hydrolysis of naringin and other flavonoids. [ABSTRACT FROM AUTHOR]

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Isoquercitrin, a rare flavonol glycoside with wide biological activities and key synthetic intermediate for the production of enzymatically modified isoquercitrin (EMIQ), was conducted by naringinase-catalyzed conversion of rutin under ultrasound irradiation. The maximum yields were obtained to 98.35 ± 3.13% and 95.20 ± 2.52% under conventional heating and ultrasound irradiation, respectively. The optimal results under ultrasound irradiation were obtained under the following conditions: rutin concentration 0.8 g/L, naringinase concentration 3000 U/L, reaction temperature 40 °C for 20 min, which was more economical than that with conventional heating. The reaction time was reduced from 60 min to 20 min, and the apparent kinetic parameter ( V m / K m ) was increased 3.72-fold. The lower activity energy E a under ultrasonic irradiation was 0.7-fold of that in an incubator reactor, which could easily initiate the enzymatic reaction. The association saturation constant K a was 1.98-fold higher than that with conventional heating, showed a better affinity between rutin and naringinase detected by surface plasmon resonance (SPR) analysis. These results suggest that ultrasound irradiation can accelerate the enzymatic synthesis of isoquercitrin from rutin. [ABSTRACT FROM AUTHOR]

Herein is reported an innovative and reproducible systemic approach for the fabrication of customized 3D hollow microspheres of polyvinyl alcohol (PVA) based on the use of aromatic boronic acids (ABAs) as crosslinkers. A dedicated experimental set-up was developed to enable microsphere formulation. Most of the boronic acids tested were able to produce hollow microspheres. Depending on the ABA used and the production conditions, hollow PVA/ABA microspheres with different morphologies, mass transfer characteristics and unprecedented thermal (up to 121 °C) stability were obtained. The crosslinking temperature proved to be an operational parameter to control membrane thickness. The hollow microspheres were evaluated in biocatalysis, with naringin hydrolysis as model system, using encapsulated naringinase. The results highlighted a naringinase high operational stability, namely in PVA microspheres crosslinked with 1,4-phenylenediboronic acid and with phenylboronic acid, with no evident loss of activity throughout seven consecutive runs, theoretically resulting in an infinite half-life. [ABSTRACT FROM AUTHOR]

Polyvinyl alcohol (PVA) electrospun nanofibers were produced using an electrospinning technique. Key parameters (e.g. collectors, distance from needle tip to collector, among others) that influence the structure and morphology of fibers were optimized. The naringinase entrapped in PVA nanofibers retained over 100% of its initial activity after 212 h of operation, at 25 °C. Chemical crosslinking with several boronic acids further increased the hydrolysis temperature (up to 85 °C) and yielded nanofibers with thermal stability up to 121 °C. A mini packed bed reactor (PBR) developed to establish the feasibility for continuous enzymatic operation, ran for 16 days at 45 °C. Highest naringenin biosynthesis was attained at a flow rate of 10 mL h −1 . Highest volumetric (78 mol L −1 h −1 ) and specific (26 mol h −1 g enzyme −1 ) productivities were attained at 30 mL h −1 . The activity of NGase in electrospun nanofibers remained constant for almost 16 days of operation at 10 mL h −1 . [ABSTRACT FROM AUTHOR]