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Introduction. The effect of hydrocolloids (xanthan gum and guar gum) on dough properties and the quality of gluten-free bread from rice and corn flour enriched with whey protein concentrate was studied. Materials and methods. For the preparation of the whey protein concentrate it was used a laboratory system with a removable flat membrane module, equipped with a 25 kDa polyacrilonitrile ultrafiltration membrane. Dough consistency was measured by degree of immersion, using automatic penetrometer. Results and discussion. Based on the preliminary experiments (with 5, 10 and 15 %) it was found that the optimal quantity of whey protein concentrate was 10 %. That is why for the further experimental tests 10 % whey protein concentrate was added to control sample bread. Addition of higher quantities of xanthan gum resulted in weak dough consistency. Concerning the dough consistency it can be concluded that the addition of xanthan gum results in release of the dough, regardless of the quantity used. The best result was obtained when 1.5 % guar gum was added. Maximum increase in bread volume was obtained with 1.5 % guar gum. The specific volume of bread significantly improved with hydrocolloids addition. It was found that the control sample had a lower specific volume. The samples containing hydrocolloids had larger volume than the control. The addition of 1 % xanthan gum resulted in an increase in H/ D index by 50 %, compared to the control sample. When 1.5 % guar gum was added, the highest results were obtainedthe increase compared to the control sample was 100 %. Guar gum had greater influence on sensory properties of gluten-free bread from rice and corn flour than xanthan gum. Addition of 1.5 % guar gum led to the best results for almost all sensory properties (without the porosity and aftertaste). The results concerning porosity and aftertaste did not differ those obtained with the addition of 1 % guar gum. Addition of 1.5 % guar gum in formulation of gluten-free bread from rice and corn flour led to the highest volume, uniform crust and crumb color, with no rust and atypical shades. The flavor was pleasant and very well pronounced, evaluated by the panelists with 8 points, while the flavor of samples with xanthan gum had 3 points. The flavor was weaker when 1 % guar gum was used (5 points). The bread samples with guar gum were appreciated as more crisp, with a very pleasant taste and aftertaste. Conclusions. For the production of gluten-free bread of rice and corn flour enriched with whey protein concentrate, the addition of 1.5 % guar gum is most appropriate.

Introduction. The effect of Spirulina platensis on the crumb firmness during storage (96 h) of wheat bread was studied by measuring the deformation properties (total, plastic and elastic deformation). Materials and methods. Bread is obtained from wheat flour with the addition of Spirulina platensis (powder) in the amount of 2 or 4% by the weight of flour. The deformation properties of the bread crumb were studied 3, 24, 48, 72 and 96 hours after the baking. The deformation characteristics of the bread crumb are measured using automatic penetrometer, by immersion of a body with a certain mass for a certain time. Results and discussion. The highest penetration, and therefore the greatest softness of the bread crumb is found in the bread with the addition of Spirulina platensis in the amount of 4% by weight of flour. In the both algae samples, the rate of firming of the crumb is slower and after 96 hours of storage the total deformation of the crumb decreases 2.75 times, while that of control sample decreases 3.6 times. Bread samples containing Spirulina platensis have a higher plasticity of the crumb during the whole period of storage (96 hours). Algae addition in the amounts of 2% and 4% by weight of the flour leads to an improvement in the plastic properties of the bread crumb and to their retention for a longer time than in the control sample. During storage in the control sample elasticity of the bread crumb gradually decreases and at the last measurement (96 hours after baking) it is 3.54 times lower compared to the first measurement-3 h after baking. The elasticity of the bread crumb is affected by the addition of Spirulina platensis. Bread samples, which recipe includes 4% Spirulina platensis have a higher elasticity of the crumb throughout the storage period. Conclusions. Crumb firmness decreased with the incorporation of Spirulina platensis powder. The addition of Spirulina platensis in the amount of 4% determines the greatest softness of the bread crumb.

Some of the biochemical properties of a crude lipase enzyme from Rhizopus arrhizus were determined. The enzyme displayed maximal catalytic activity at рН 9.0 and temperature of 35ºС. It was stable at basic values of pH and 40°C and in the presence of detergents. Lipase showed substrate specificity against different plant oils. Three multiplicity forms of the enzyme (Lip I, Lip II and Lip III) were isolated by gel chromatography. They differed in their molecular weight (Lip I-80 000 Da, Lip II-39 700 Da and Lip III-6 900 Da) and degree of glycosylation (51.61% for Lip I, 74.17% for Lip II and 55.60% for Lip III). Some of the specific biochemical properties of the multiplicity forms were established. No synergistic effect of the three multiplicity forms of lipase in hydrolysis of olive oil was observed.