JOURNAL OF ENGINEERING & PROCESSING MANAGEMENT

XANTHAN PRODUCTION ON CRUDE GLYCEROL BY LAB-SCALE BIOREACTOR CULTIVATION OF LOCAL Xanthomonas ISOLATE

Ida Zahović — 2023-09-05

Intensive development of the global biodiesel industry has led to the generation of a large excess of crude glycerol, which is impure, and its disposal into the environment is unacceptable without previous purification. Since purification costs are high, the application of crude glycerol in biotechnological production of valueadded products represents a promising solution for a sustainable utilization of this effluent. The aim of this study was to examine xanthan biosynthesis by the Xanthomonas PL 3 strain on a medium containing crude glycerol from biodiesel production in a laboratory-scale bioreactor in order to further scale up this bioprocess. Xanthan was produced by submerged cultivation in a crude glycerol-based medium (glycerol content of 20 g/L) in a 3 L lab-scale bioreactor (working volume of 2 L), under aerobic conditions for 168 h (0-48 h: 25°C, 1 vvm and 200 rpm; 48-168 h: 30 °C, 2 vvm, and agitation rate adjusted according to the dissolved oxygen concentration which was maintained at values higher than 30%). The bioprocess was monitored by the analysis of cultivation medium samples in predetermined time intervals, and its success was estimated based on the xanthan concentration in the medium, separated biopolymer average molecular weight and degree of nutrient conversion. In the applied experimental conditions, 11.10 g/L of xanthan with the average molecular weight of 2.85·105 g/moL was biosynthesized. At the end of this bioprocess, the degree of total glycerol, nitrogen and phosphorous conversion was 62.82%, 41.54% and 24.80%, respectively. Results obtained in this study suggest that the Xanthomonas PL 3 strain has the ability to produce xanthan of good quality on cultivation media containing crude glycerol from the biodiesel industry.

Research of the effect of cold atmospheric plasma on gluten proteins from gluten-free flour

Vesna Gojković Cvjetković — 2023-09-05

A gluten-free diet is the only available therapy for people with celiac disease (CD) and wheat allergy (WA). Given that this type of diet is difficult to implement because there is a possibility that gluten-free products could be contaminated with gluten, the aim of this paper was to examine the effect of cold plasma treatment on gluten proteins present in gluten-free flour. Samples were treated in a solid state (4 min) and as extracts (1 min). After treatment, proteins were separated on an HPLC apparatus. Then, the samples that were treated (in the solid form and as extracts) were compared to the untreated samples. Based on the obtained results, fewer proteins were isolated from the samples that were treated, compared to the untreated ones.

THE CHARACTERIZATION OF SILYMARIN AND SILIBININ LIPOSOMES

Aleksandra A. Jovanović — 2023-09-05

The aim of the present study was the characterization of silymarin and silibinin liposomes via determination of encapsulation efficiency, particle size, polydispersity index (PDI), zeta potential, mobility, and conductivity, as well as storage stability during 28 days at 4ºC and stability after UV irradiation. Encapsulation efficiencies of silymarin and silibinin were 92.05±1.41% and 87.86±2.06%, respectively. Particle size and PDI of the liposomes with silymarin were changed from 3541.3±62.5 nm to 2677.0±44.2 nm and from 0.346±0.044 to 0.228±0.036, respectively, during the 28-day stability study; particle size and PDI of the liposomes with silibinin were changed from 2074.7±19.4 nm to 2704.0±35.0 nm and from 0.328±0.030 to 0.456±0.026, respectively. The Zeta potential of the silymarin-loaded liposomes and silibinin-loaded liposomes was changed from -27.0±0.7 mV to -26.4±0.4 mV and from -29.4±0.6 mV to -29.0±0.4 mV, respectively. Mobility and conductivity of the liposomes with silymarin were changed from -2.120±0.057 μmcm/Vs to - 2.067±0.028 μmcm/Vs and from 0.017±0.005 mS/cm to 0.009±0.004 mS/cm, respectively. Mobility and conductivity of the liposomal particles with silibinin were changed from -2.307±0.053 μmcm/Vs to -2.110±0.033 μmcm/Vs and from 0.018±0.003 mS/cm to 0.060±0.001 mS/cm, respectively. UV irradiation did not affect particle size and PDI of all liposomes, but it caused a decrease in zeta potential: -23.9±0.8 mV for silymarin and -24.5±0.7 mV for silibinin, in mobility: - 1.874±0.064 μmcm/Vs for silymarin and -1.920±0.057 μmcm/Vs for silibinin, and in conductivity: 0.014±0.001 mS/cm for silymarin and 0.007±0.003 mS/cm for silibinin. Overall, the obtained results qualify liposomes to be used as silymarin and silibinin carriers for application in functional foods and pharmaceutical products.

EFFECT OF FORMULATION VARIABLES ON SENSORY QUALITY OF THERMO-REVERSIBLE FRUIT FILLING FOR FROZEN SEMI-FINISHED BAKERY PRODUCTS: MODELLING AND OPTIMIZATION

Slavica Grujić — 2023-09-05

Development of a food product requires integrated scientific and professional knowledge on the technological process, the final product and, the quality of the ingredients and their interaction. This research examined the effect of formulation variables on the sensory quality of a thermo-reversible sour cherry fruit filling, as well as the modelling and optimization of the variables for achieving the quality suitable for filling frozen semi-finished bakery products in industrial conditions. Each formulation for 15 model-samples was successively corrected, to achieve the appropriate sensory quality of the filling in finished products after baking. Their quality was evaluated by descriptive sensory and physico-chemical methods of analysis and compared. The basic formulation for the filling was defined after the successive production of 7 model-samples in laboratory conditions, their use in industrial conditions (puff pastry filling, shaping, quick freezing, storage for at least 24 hours at -18°C, baking and cooling to room temperature) and analysing their quality. Further formulation optimization included selecting: the type and amount of fruits (sour cherry, apple), food additives and cherry flavour for 8 new model-samples. The formulation and ingredients for the fruit filling production (30% sour cherry fruit, 30% apple puree, 58% sugar, 2% starch, 1% pectin, 0.03% firming agent E509, 0.03% acidity regulator E331, 0.025% cherry flavour) and quality parameters (dry matter 65%, acidity 0.85%, pH = 3.2-3.4) were defined. The fruit filling had appropriate sensory quality before and after baking of filled puff pastry: clear cherry-red colour, moderately firm consistency and stable volume, rich fruity aroma, and refreshing sweet-sour taste. The results also confirmed that the product was suitable for manual or machine filling of raw dough.

Implementation of the electrohydrodynamics’ perfect dielectric model in OpenFOAM®

Stefan A. Bošković — 2023-09-05

The electrohydrodynamics’ (EHD) perfect dielectric model was added into computational fluid dynamics (CFD) software OpenFOAM® in order to improve its usability for the EHD field and specifically for the mentioned model. Based on the investigated literature, it can be said that this is the most complete implementatiton of the said model. Two sets of numerical simulations with two different fluids are presented and analyzed. One set is one-dimensional. The other set is with a drop of one fluid surrounded by other fluid. Oscillations can be observed with certain expressions or calculation strategies for the electrostrictive force, and used for disregarding them. Results that are closer to analytical predictions can be obtained by using appropriate expression for the dielectric force. The electrostrictive force was implemented not only for nonpolar, but also for polar fluids, and it is shown that it might significantly influence the drop deformation. Calculated and analytically predicted drop deformations were close or comparable even up to around 0.25, what is significantly higher and different from a previous study made by other authors. Different expressions for the electric permittivity and usage of limiters for volume fractions were investigated. Conclusions from this paper can be transferred to more complicated models.