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Prevention of β-Glucosidase Inhibition by High Molecular Mass Compounds During Enzymatic Wine Aroma Enhancement Using a Hollow Fiber Reactor

Alicia Graciela Cid*, Mirta Daz and Guillermo Ellenrieder


National Research Institute for Chemical Industry (National University of Salta, National Council of Scientific and Technical Research), Av. Bolivia 5150, 4400 Salta, Argentina

Article history
:

Received May 21, 2013
Accepted March 4, 2014

Key words
:

glycosidases, β-glucosidase inhibition and stability in wine, wine aroma, membrane reactor

Summary:

Enzyme activity and stability in a membrane reactor for wine aroma enhancement can be higher than when the enzyme is present in a free state since the catalyst would only be in contact with the low molecular mass components of this beverage. To test this hypothesis, the activity and stability of two commercial β-glucosidases were measured in the presence of Tannat wine and of its low molecular mass fraction (<10 kDa) obtained by ultrafiltration. The relative activities of Endozym Rouge and Endozym β-split β-glucosidases were higher in this fraction (3.8 and 7.6 %, respectively) than in the whole wine (0.9 and 5.6 %, respectively). Both enzymes were also more stable in the low molecular mass fraction. Endozym β-split β-glucosidase retained about 75 % of its initial activity after 14 days in the low molecular mass fraction, as contrasted with only 37.5 % in the wine. The ability of Endozym Rouge β-glucosidase to hydrolyze the synthetic substrate p-nitrophenylglucoside was examined in a simple batch membrane reactor. A rate of hydrolysis comparable to that obtained with the free Endozym Rouge β-glucosidase was reached. Finally, Endozym β-split β-glucosidase was used to hydrolyze the synthetic substrate in a hollow fiber membrane reactor and a substrate conversion near 58 % was achieved.


*Corresponding author:        agcid@unsa.edu.ar
                                                    
    
+54 387 425 1006
                                            +54 387 425 1006

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Effects of Gelatin-Based Edible Films Enriched with Laurel Essential Oil on the Quality of Rainbow Trout (Oncorhynchus mykiss) Fillets During Refrigerated Storage

Yunus Alparslan*, Tuba Baygar, Taçnur Baygar, Hatice Hasanhocaoglu and Cansu Metin


Mugla Sitki Kocman University, Faculty of Fisheries, Kotekli, TR-48000 Mugla, Turkey

Article history
:

Received June 4, 2013
Accepted February 6, 2014

Key words
:

gelatin films, laurel essential oil, rainbow trout, Oncorhynchus mykiss, shelf-life

Summary:

The effects of gelatin films enriched with laurel leaf essential oil on the quality of rainbow trout (Oncorhynchus mykiss) during refrigerated storage at (41) °C were examined over a period of 26 days. Fish fillets were wrapped with 8 % gelatin films containing 0, 0.1 and 1 % (by volume per mass) of laurel essential oil and vacuum packaged. Sensory (raw and cooked fish), microbiological (total viable counts, psychrotrophic bacteria counts, Enterobacteriaceae and lactic acid bacteria) and chemical (proximate composition, pH, total volatile base nitrogen (TVB-N), thiobarbituric acid (TBA), free fatty acid (FFA) and peroxide value (PV)) analysis, and colour measurement were carried out during the storage period and shelf-life was determined periodically. The obtained results showed that the gelatin film enriched with laurel essential oil was suitable for the preservation of rainbow trout fillet and the ability of laurel essential oil to preserve the film depended on its ratio. Combined effects of gelatin film and laurel essential oil (1 % by volume per mass) was efficient in maintaining the quality characteristics at an acceptable level up to 22 days of storage, while the control and gelatin film without the essential oil reached an unacceptable level at 15 and 20 days, respectively.



*Corresponding author:        yunusalparslan@mu.edu.tr
                                                    
    
+90 252 211 3169
                                            +90 252 211 1887

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Comparison of Sensory Properties, Shelf-Life and Microbiological Safety of Industrial Sausages Produced with Autochthonous and Commercial Starter Cultures

Jadranka Frece1, Dragan Kovačević2, Snježana Kazazić3, Jasna Mrvčić1, Nada Vahčić1, Damir Ježek1, Mirjana Hruškar1, Ivona Babić4 and Ksenija Markov1*


1Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia
2Faculty of Food Technology, Josip Juraj Strossmayer University of Osijek, Kuhačeva 20, HR-31 000 Osijek, Croatia
3Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia
4Ministry of Agriculture, Fisheries and Rural Development, Ulica grada Vukovara 78, HR-10000 Zagreb, Croatia

Article history
:

Received November 11, 2013
Accepted April 4, 2014

Key words
:
autochthonous starter cultures, sausage production, sensory properties, lactic acid bacteria, staphylococci

Summary:

The aim of this research is to use isolated and characterized autochthonous functional starter cultures from traditional Croatian dry sausages and to evaluate their capacity for industrial production of five sausages (Čajna sausage, Zimska sausage, Bečka sausage, Srijemska sausage and Slavonski kulen). These defined autochthonous functional starter cultures (combination of Lactobacillus and Staphylococcus strains) were used to produce five different industrial sausages which were compared by a panel. The viability of introduced autochthonous Lactobacillus and Staphylococcus strains and their effect on the final product characteristics, namely microbiological, physicochemical and sensory properties were monitored. The obtained results indicate that autochthonous starter cultures survived industrial production of sausages and can be used for production of sausages under controlled conditions. Autochthonous starter cultures obtained better results in the organoleptic evaluation, microbial safety and prolonged shelf-life in comparison with commercial starter cultures.



*Corresponding author:        kmarko@pbf.hr
                                                    
    
+385 1 460 5284
                                            +385 1 483 6424

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Effect of the Degree of Polymerization of Inulin on the Rate of Hydrolysis Using Immobilized Inulinase

Stefano Curcio*, Emanuele Ricca, Vincenza Calabrò and Gabriele Iorio


Laboratory of Transport Phenomena and Biotechnology, Department of Informatics, Modeling, Electronics and Systems Engineering (D.I.M.E.S.), University of Calabria, Ponte P. Bucci, cubo 39/c, IT-87036 Rende, Italy

Article history
:

Received August 23, 2013
Accepted April 4, 2014

Key words
:

immobilized enzyme, kinetic analysis, degree of polymerization, inulinase, fructose syrup

Summary:

The present paper addresses two crucial features in the industrial development of fructose production by enzymatic hydrolysis of inulin: the use of immobilized biocatalyst in the hydrolysis of crude extracts of chicory roots and the evaluation of the effect of degree of polymerization of inulin on the overall reaction rate. The immobilized biocatalyst consisted of inulinase covalently bound to Sepabeads® supports. It was demonstrated that its catalytic activity towards crude inulin extract (real substrate) was much higher than that exhibited towards pure inulin (synthetic solution). Experiments revealed that, in applications of practical interest with real substrate, the activity of immobilized enzyme was as high as 63 % of that of free enzyme in homogeneous solution. This certainly was a driving force to potential industrial application of this immobilized enzyme preparation. Therefore, the effect of pure and crude substrates on the kinetics of the reaction catalysed by the immobilized enzyme was investigated. The kinetic analysis revealed a Michaelis-Menten dependence of the reaction rate on substrate concentration for both pure (high molecular mass) and crude (low molecular mass) inulin. Interesting results were derived from the comparison of Km and vmax values in the two cases. In particular, it was found that increasing degree of polymerization of the substrate caused vmax decrease and Km increase. After evaluation of mass transport effects, this was mainly associated with a different substrate/ enzyme affinity when exploiting inulin characterized by different (low or high) degree of polymerization.



*Corresponding author:        stefano.curcio@unical.it
                                                    
    
+39 0984 496 711
                                            +39 0984 494 043

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Antioxidant and Prebiotic Activity of Enzymatically Hydrolyzed Lychee Fruit Pulp

Naraporn Fasawang1 and Pranee Anprung2*


1
Program in Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
2Department of Food Technology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand

Article history
:

Received August 27, 2013
Accepted April 29, 2014

Key words
:

pectinase, lychee pulp, antioxidation, prebiotics

Summary:

The optimal extraction of bioactive compounds from lychee fruits using commercial Pectinex® Ultra SP-L pectinase hydrolysis of the fruit pulp homogenate was evaluated. The  lychee fruit pulp was treated with the pectinase at volume per mass ratios between 0.5 and 2.5 % for 0.5–5 h. The degree of hydrolysis (DH), monitored as the level of released reducing sugar, increased with the increase of enzyme volume per mass ratio and time up to 2 % and 4 h, respectively, to give a maximum DH of 19 %. The antioxidant activity in lychee pulp hydrolysates increased with increasing DH, with the highest DH of 19 % displaying an EC50 of 0.25 g of fresh mass (FM) per g of diphenyl-(2,4,6-trinitrophenyl)- iminoazanium and 53.17 M of Trolox equivalents per g of FM. The lychee hydrolysate with the DH of 19 % had the highest level of total phenolic acids (165.8 mg of gallic acid equivalents per 100 g of FM) and flavonoids (70.8 mg of catechin equivalents per 100 g of FM), and the highest prebiotic activity score of 1.68 and 0.82 of Bifidobacterium lactis Bb12 and Lactobacillus acidophilus La5, respectively. In accordance with the level of phenolic acids and flavonoids, the lychee hydrolysate with the DH of 19 % revealed a reasonably good level (72–77 %) of lipid peroxidation inhibition in soya bean, lard and olive oil. The lychee hydrolysate with the DH of 19 % increased the number of detected volatile compounds to 37, with 11 new compounds that were not found in the lychee hydrolysate with the DH of 0 %. Moreover, the particle size and insoluble fibre level were reduced with a concomitant increase in the soluble fibre level.



*Corresponding author:        pranee.a@chula.ac.th
                                                    
    
+66 2 218 5530
                                            +66 2 254 4314

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