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Gluten as a Standard of Wheat Flour Quality

Duška Ćurić*, Damir Karlović, Dubravka Tušak, Biserka Petrović and Jelena Đugum


Department of Food Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia

Article history:

Received August 3, 2010
Accepted February 3, 2011

Key words:

wheat, flour, gluten index, physical dough properties

Summary:

The quantity and quality of gluten are considered the most important quality parameters of wheat flour. Gluten Index Method (GIM) is a rather new method for determining gluten quantity and quality in wheat semolina and flour. This study reports on values for flours obtained from the most important Croatian wheat cultivars. The gluten index value in the tested flour samples varied from 55.92 (Patria cultivar) to 99.60 % (Marija cultivar).This high variety was not only due to cultivar differences but also to different climate conditions (especially cultivars Žitarka and Sana). The determination of gluten quantity and quality by Gluten Index Method is compared with the determination by other methods. A significant positive linear correlation was observed between the values of gluten index and extensographic values of flour quality, i.e. between the gluten index and maximal resistance of dough to extensibility (r = 0.860), dough energy (r = 0.799) and dough resistance at 50 mm (r = 0.788). That indicates that the gluten index actually defines technological flour quality. The optimal gluten index values for bread production using Croatian wheat cultivars were between 75 and 90 %.  



*Corresponding author:           dcuric@pbf.hr
                                               ++385 1 460 6268
                                               ++385 1 460 6286

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Use of the Foster-Niemann Equation in Study of the Enzymic Processes

Ivan Marković1*, Velimir Topolovec2, Branka Marković-Devčić1 and Vladimir Marić3

1PLIVA d.d., Research and Development, Prilaz baruna Filipovića 25, HR-10000 Zagreb, Croatia
2Computer Science Department, Faculty of Philosophy, University of Rijeka, Omladinska 14, HR-51000, Rijeka, Croatia
3Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, Pierottijeva 6, HR-10000 Zagreb, Croatia

Article history:

Received March 15, 2001
Accepted November 8, 2001

Key words:

Foster-Nieman equation, enzyme kinetics, proteinase, cellulase, β-glucosidase, amylase

Summary:

The Foster-Niemann equation enables the analysis of kinetic data from long-term enzymic reactions in which products of the reaction inhibit a process. In this way the inevitable errors in estimation of initial rates, needed for reaction constants calculation, can be avoided. Initially, Foster-Niemann equation was used in reevaluation of the kinetic constants of previously studied specific substrates of α-chymotrypsin. Enzymic hydrolysis of biopolymers are very complex, and reaction products generally inhibit the reaction. Therefore, the equation was very useful both in the preliminary studies of unknown processes and in the elucidation of the reaction mechanisms. In the processes in which soluble enzyme reacts with insoluble substrate the basic Foster-Niemann equation was modified for the reactions in heterogeneous systems. Thus, the appropriate forms of the Foster-Niemann equation were employed in the study of starch, cellulose, cellobiose, barley 1,3 and 1,4-β-D-glucan and protein hydrolysis. By means of these equations the rection mechanisms were elucidated, the kinetic constants evaluated and kinetic and mathematical models of the reaction systems developed.  



*Corresponding author:          Ivan.Markovic@Pliva.hr
                                               ++385 (0)1 3781 966
                                               ++ 385 (0)1 3781 606

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Morphological Characteristics, Extracellular and Intracellular Protein and Enzyme Patterns of Five Aspergillus Species

Katarina Jernejc* and Aleksa Cimerman


National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia

Article history:

Received March 23, 2001
Accepted November 8, 2001

Key words:

morphology, isozymes, taxonomy, Aspergilli

Summary:

Six biotechnologically interesting Aspergilli, four of which were isolated lately and included in the culture collection of National Institute of Chemistry MZKI, were examined morphologically and biochemically. Since species may no longer produce typical morphological, structures, some nonmorphological methods in classification were used. Based on both macroscopic and microscopic observations, using an identification key, individual isolates were classified within the genus Aspergillus, belonging to three subgenera, four sections, five species and two A. niger strains. In different Aspergilli differences in the amounts of total lipids, sterols and fatty acids were observed, but they were not significant enough to distinguish between species. Intracellular  protein profiles did not differ between the two A. niger strains, neither were they different in A. oryzae and A. flavus, both belonging to the section Flavi. Differences appeared between sections Nigri and Flavi, belonging to the subgenera Circumdati, but the largest differences were observed on the subgenus level. Enzyme analyses clearly differ among fungi examined on the basis of the number of isozyme bands and their molecular weights. Isocitrate dehydrogenase revealed one band, whereas acid phosphatases two or three bands, in all examined fungi. Malate dehydrogenases showed one and lactate dehydrogenases one band or two isozyme bands. Differences on the subgenus level, with the results obtained, were greatest, but differences at strain level could also be seen.



*Corresponding author:           katarina.Jernejc@ki.si
                                               ++386 (0)1 4760 334
                                               ++386 (0)1 4259 244

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Isolation of Carvacrol Assimilating Microorganisms

Blagica Schwämmle1, Eleonora Winkelhausen1, Slobodanka Kuzmanova1* and Walter Steiner2


1
Faculty of Technology and Metallurgy, University »Sv. Kiril i Metodij« Skopje, Macedonia

2Institute of Biotechnology, Technical University Graz Petersgasse 12/I, A-8010, Austria

Article history:

Received March 21, 2001
Accepted June 20, 2001

Key words:

selection, carvacrol, bacterial isolates, fungal isolates

Summary:

Several bacteria and fungi capable of assimilating carvacrol were isolated from the herbs oregano, thyme and savory, and pine tree (resin, bark and needles). When cultivated in a liquid medium with carvacrol, as a sole carbon source, the bacterial isolates from savory and pine consumed the carvacrol in the range of 19–22 % within five days of cultivation. The fungal isolates grew much slower and after 13 days of cultivation consumed 7.1–11.4 % carvacrol. Pure strains belonging to the bacterial genera of Bacterium, Bacillus and Pseudomonas, as well as fungal strain from Aspergillus, Botrytis and Geotrichum genera were also tested for their ability to grow in medium containing carvacrol. Among them, only in Bacterium sp. and Pseudomonas sp. carvacrol uptake was monitored. Both Pseudomonas sp. 104 and 107 consumed the substrate in the amount of 19 %. These two strains also exhibited the highest cell mass yield and the highest productivity (1.1 and 1.2 g/L per day).



*Corresponding author:           KuzmanS@ereb1.mf.ukim.edu.mk
                                               ++389 (0)2 364 588
                                               ++389 (0)2 365 389

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Immunostimulatory Effects of Fungal Polysaccharides from Ganoderma lucidum Submerged Biomass Cultivation

Jožica Habijanič1, Marin Berovič1*, Branka Wraber2, Damjan Hodzar3 and Bojana Boh3


1
National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana

2Institute of Microbiology and Immunology, Medical Faculty, University of Ljubljana
3Faculty of Science and Engineering, University of Ljubljana
*Department of Chem. Biochem. Engineering, University of Ljubljana, Slovenia

Article history:

Received April 6, 2001
Accepted September 5, 2001

Key words:

Ganoderma lucidum, submerged biomass cultivation, polysaccharides, cytokine assay, TNF-α, IFN-γ

Summary:

A Slovenian Ganoderma lucidum strain MZKI G97 was isolated and cultivated in a 10 L stirred tank reactor, on potato dextrose substrate. Biomass up to 15.2 g L–1 and fungal polysaccharides were produced. The extracellular polysaccharide fraction was obtained by the precipitation method with ethanol. Four intracellular polysaccharide fractions were obtained by the hot-water extraction and precipitation with ethanol, by ammonium oxalate extraction, and by extraction with sodium hydroxide, followed by precipitation with acetic acid and precipitation with ethanol. Immunostimulatory effects of isolates were tested on induction of cytokine (TNF-α, IFN-γ) synthesis in primary cultures of human mononuclear cells (PBMC) isolated from a buffy coat. Results have shown the potential of isolates to induce moderate amounts of TNF-α (max. 630 pg mL–1of a culture supernatant), and IFN-γ in trace amounts (max. 11.5 pg mL–1), respectively. The TNF-α inducing activity is comparable to romurtide, which has been used as a supporting therapy in cancer patients treated with radiotherapy and/or chemotherapy. 



*Corresponding author:        marin.berovic@uni-lj.si
                                                          ++ 386 1 2419 510
                                            ++ 386 14259 244

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