TY  - JOUR
AU  - Vajic, Una-Jovana
AU  - Grujic-Milanovic, Jelica
AU  - Živković, Jelena Č.
AU  - Savikin, Katarina
AU  - Gođevac, Dejan
AU  - Miloradović, Zoran
AU  - Bugarski, Branko
AU  - Mihailovic-Stanojevic, Nevena
PY  - 2015
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/1717
AB  - A full three level factorial design was implemented for optimization of extraction parameters in order to maximize total phenolic (TP) yield from stinging nettle leaf. Factors considered were percentage of methanol in solvent (X-1 : 50-100% methanol) and extraction time (X-2: 30-90 min), and maceration was used as extraction method. A second-order polynomial model was applied for fitting experimental data and predicting the response, and this mathematical model produced a satisfactory fit (R-2 = 0.993,p LT 0.01). The optimal extraction conditions were 54% aqueous methanol and 38 min extraction time, while maximal theoretical TP yield was 8.9 mg GAE/g DW. Solvent composition significantly affected extraction efficiency causing decrease of TP yield with increase of methanol percentage. On the other hand, extraction time did not influence significantly efficiency of extraction. Using LC/MS and HPLC analysis we detected and quantified three most abundant phenolic compounds: 2-O-caffeoyl malic acid, chlorogenic acid, and rutin. Comparison between maceration and ultrasound-assisted extraction (UAE) obtained extracts based on TP content as well as antiradical activity and HPLC results, showed that UAE have a better extraction capability affecting yield and time of extraction. Of all tested extracts, 54% aqueous methanolic extracts obtained with UAE and 38 min extraction time had the highest TP content.
PB  - Elsevier
T2  - Industrial Crops and Products
T1  - Optimization of extraction of stinging nettle leaf phenolic compounds using response surface methodology
VL  - 74
SP  - 912
EP  - 917
DO  - 10.1016/j.indcrop.2015.06.032
ER  - 

@article{
author = "Vajic, Una-Jovana and Grujic-Milanovic, Jelica and Živković, Jelena Č. and Savikin, Katarina and Gođevac, Dejan and Miloradović, Zoran and Bugarski, Branko and Mihailovic-Stanojevic, Nevena",
year = "2015",
abstract = "A full three level factorial design was implemented for optimization of extraction parameters in order to maximize total phenolic (TP) yield from stinging nettle leaf. Factors considered were percentage of methanol in solvent (X-1 : 50-100% methanol) and extraction time (X-2: 30-90 min), and maceration was used as extraction method. A second-order polynomial model was applied for fitting experimental data and predicting the response, and this mathematical model produced a satisfactory fit (R-2 = 0.993,p LT 0.01). The optimal extraction conditions were 54% aqueous methanol and 38 min extraction time, while maximal theoretical TP yield was 8.9 mg GAE/g DW. Solvent composition significantly affected extraction efficiency causing decrease of TP yield with increase of methanol percentage. On the other hand, extraction time did not influence significantly efficiency of extraction. Using LC/MS and HPLC analysis we detected and quantified three most abundant phenolic compounds: 2-O-caffeoyl malic acid, chlorogenic acid, and rutin. Comparison between maceration and ultrasound-assisted extraction (UAE) obtained extracts based on TP content as well as antiradical activity and HPLC results, showed that UAE have a better extraction capability affecting yield and time of extraction. Of all tested extracts, 54% aqueous methanolic extracts obtained with UAE and 38 min extraction time had the highest TP content.",
publisher = "Elsevier",
journal = "Industrial Crops and Products",
title = "Optimization of extraction of stinging nettle leaf phenolic compounds using response surface methodology",
volume = "74",
pages = "912-917",
doi = "10.1016/j.indcrop.2015.06.032"
}

Vajic, U., Grujic-Milanovic, J., Živković, J. Č., Savikin, K., Gođevac, D., Miloradović, Z., Bugarski, B.,& Mihailovic-Stanojevic, N.. (2015). Optimization of extraction of stinging nettle leaf phenolic compounds using response surface methodology. in Industrial Crops and Products
Elsevier., 74, 912-917.
https://doi.org/10.1016/j.indcrop.2015.06.032

Vajic U, Grujic-Milanovic J, Živković JČ, Savikin K, Gođevac D, Miloradović Z, Bugarski B, Mihailovic-Stanojevic N. Optimization of extraction of stinging nettle leaf phenolic compounds using response surface methodology. in Industrial Crops and Products. 2015;74:912-917.
doi:10.1016/j.indcrop.2015.06.032 .

Vajic, Una-Jovana, Grujic-Milanovic, Jelica, Živković, Jelena Č., Savikin, Katarina, Gođevac, Dejan, Miloradović, Zoran, Bugarski, Branko, Mihailovic-Stanojevic, Nevena, "Optimization of extraction of stinging nettle leaf phenolic compounds using response surface methodology" in Industrial Crops and Products, 74 (2015):912-917,
https://doi.org/10.1016/j.indcrop.2015.06.032 . .

TY  - JOUR
AU  - Vujčić, Zoran
AU  - Miloradović, Zoran
AU  - Milovanović, Aleksandra
AU  - Božić, Nataša
PY  - 2011
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/921
AB  - Yeast cell wall invertase (CWI) was immobilised within 10% gelatin hydrogel. The result of entrapment was the complete immobilisation of all the added CWI. The activity of immobilised biocatalyst was 93 +/- 3 U/g, with activity yield of 30%. The optimum pH was in range of 4.5-5.0 for free and immobilised biocatalyst. The optimum temperature was 60 degrees C for both free and gelatin immobilised CWI. Immobilised CWI was more stable than free CWI above optimum activity temperatures. The K-m of free and immobilised CWI was 35.10 +/- 2.99 mM and 71.45 +/- 3.23 mM, respectively. The V-max, values were estimated as 8.23 +/- 0.24 mM/min and 0.121 +/- 0.002 mM/min, respectively. Immobilised CWI was tested in a batch reactor using 50% sucrose (w/v). After 70 consecutive cycles gelatin immobilised CWI retained 75% of its original activity.
PB  - Elsevier Sci Ltd, Oxford
T2  - Food Chemistry
T1  - Cell wall invertase immobilisation within gelatin gel
VL  - 126
IS  - 1
SP  - 236
EP  - 240
DO  - 10.1016/j.foodchem.2010.11.010
ER  - 

@article{
author = "Vujčić, Zoran and Miloradović, Zoran and Milovanović, Aleksandra and Božić, Nataša",
year = "2011",
abstract = "Yeast cell wall invertase (CWI) was immobilised within 10% gelatin hydrogel. The result of entrapment was the complete immobilisation of all the added CWI. The activity of immobilised biocatalyst was 93 +/- 3 U/g, with activity yield of 30%. The optimum pH was in range of 4.5-5.0 for free and immobilised biocatalyst. The optimum temperature was 60 degrees C for both free and gelatin immobilised CWI. Immobilised CWI was more stable than free CWI above optimum activity temperatures. The K-m of free and immobilised CWI was 35.10 +/- 2.99 mM and 71.45 +/- 3.23 mM, respectively. The V-max, values were estimated as 8.23 +/- 0.24 mM/min and 0.121 +/- 0.002 mM/min, respectively. Immobilised CWI was tested in a batch reactor using 50% sucrose (w/v). After 70 consecutive cycles gelatin immobilised CWI retained 75% of its original activity.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Food Chemistry",
title = "Cell wall invertase immobilisation within gelatin gel",
volume = "126",
number = "1",
pages = "236-240",
doi = "10.1016/j.foodchem.2010.11.010"
}

Vujčić, Z., Miloradović, Z., Milovanović, A.,& Božić, N.. (2011). Cell wall invertase immobilisation within gelatin gel. in Food Chemistry
Elsevier Sci Ltd, Oxford., 126(1), 236-240.
https://doi.org/10.1016/j.foodchem.2010.11.010

Vujčić Z, Miloradović Z, Milovanović A, Božić N. Cell wall invertase immobilisation within gelatin gel. in Food Chemistry. 2011;126(1):236-240.
doi:10.1016/j.foodchem.2010.11.010 .

Vujčić, Zoran, Miloradović, Zoran, Milovanović, Aleksandra, Božić, Nataša, "Cell wall invertase immobilisation within gelatin gel" in Food Chemistry, 126, no. 1 (2011):236-240,
https://doi.org/10.1016/j.foodchem.2010.11.010 . .