Textural characteristics of fermented milk beverages produced by kombucha

Rheological properties of fermented dairy products are very important parameters of the product quality. The behaviour of gel formed during fermentation of milk is influenced by a great number of factors, such as: milk composition, starter culture, flavourings addition, etc. The aim of this research was to examine the influence of fat content, and kombucha inoculum concentration on textural characteristics of fermented milk beverages: firmness, consistency, cohesiveness and viscosity index after production and during 10 days of storage. Higher fat content of beverage affects the firmness, consistency, cohesiveness and viscosity index, while higher amount of inoculum in beverages has an opposite effect on textural characteristics of samples during storage

Improving the texture and rheology of set and stirred kombucha fermented milk beverages by addition of transglutaminase

U radu je ispitana mogućnost proizvodnje fermentiranih mliječnih napitaka uz primjenu koncentriranog kombucha inokuluma i s dodatkom transglutaminaze (TG). Glavni ciljevi rada bili su ispitati utjecaj koncentriranog inokuluma kombuche i dodatka transglutaminaze na teksturalna, reološka i senzorska svojstva čvrstih i tekućih fermentiranih mliječnih napitaka. Rezultati pokazuju da dodatak transglutaminaze u mlijeko značajno utječe na teksturalna i reološka svojstva kombucha fermentiranih mliječnih napitaka. Čvrstoća i konzistencija kombucha fermentiranih mliječnih napitaka značajno je povećana primenom transglutaminaze u odnosu na kontrolni uzorak. Čvrsti uzorci s transglutaminazom imali su 90 % veću površinu histerezisne petlje u usporedbi s tekućim uzorcima, dok je površina histerezisne petlje tekućih uzoraka bez transglutaminaze bila oko 60 % manja u usporedbi s čvrstim uzorcima kombucha fermentiranih mliječnih proizvoda. Enzimski tretman mlijeka s transglutaminazom poboljšao je teksturalna i reološka svojstva, i senzorske karakteristike čvrstih i tekućih fermentiranih mliječnih napitaka dobivenih primjenom koncentriranog kombucha inokuluma.The possibilities of manufacturing fermented milk beverages by applying kombucha inoculum concentrated by evaporation and with addition of transglutaminase have been investigated. The main aims of this study were to investigate influence of concentrated kombucha inoculum and the addition of transglutaminase (TG) on textural, rheological and sensory properties of set and stirred fermented milk beverages. The results showed that the addition of transglutaminase had a great influence on textural characteristics and rheological properties of kombucha fermented milk beverages. Firmness and consistency of kombucha fermented milk products were significantly increased with the incorporation of TG compared to the control sample. Set samples with TG addition had approximately 90 % higher hysteresis loop area compared to stirred samples, while hysteresis loop area of stirred samples without TG was 60 % lower compared to set samples. The enzymatic treatment of milk with TG improved texture, rheology and sensorial characteristics of set and stirred fermented milk beverages obtained by concentrated kombucha inoculum

Detection of bacteria Xanthomonas campestris pv. campestris on cabbage seed

U peridu 2015-2017. god. izvršeno je sakupljanje semena kupusa i utvrđivanje prisustva fitopatogenih bakterija. Sakupljeno je 37 uzoraka (sertifikovanog i naturalnog) semena, od kojih je kod 15 uzoraka primećena pojava žutih kolonija koje podsećaju na predstavnike roda Xanthomonas. Na osnovu pozitivnih rezultata provere patogenosti, biohemijsko-fizioloških i seroloških odlika izolati su identifikovani kao vrsta Xanthomonas campestris pv. campestris.In the period 2015-2017. collection of seed cabbage and detection of phytopathogenic bacteria was carried out. 37 samples (certified and natural seed) were collected, of which in 15 samples were observed yellow colonies typical for the genus Xanthomonas. Based on results of the pathogenicity, biochemical-physiological and serological tests, the isolates were identified as Xanthomonas campestris pv. campestris

Modeling and Optimization of Herb-Fortified Fresh Kombucha Cheese: An Artificial Neural Network Approach for Enhancing Quality Characteristics

In this study, an Artificial Neural Network (ANN) model is used to solve the complex task of producing fresh cheese with the desired quality parameters. The study focuses on kombucha fresh cheese samples fortified with ground wild thyme, supercritical fluid extract of wild thyme, ground sage and supercritical fluid extract of sage and optimizes the parameters of chemical composition, antioxidant potential and microbiological profile. The ANN models demonstrate robust generalization capabilities and accurately predict the observed results based on the input parameters. The optimal neural network model (MLP 6-10-16) with 10 neurons provides high r2 values (0.993 for training, 0.992 for testing, and 0.992 for validation cycles). The ANN model identified the optimal sample, a supercritical fluid extract of sage, on the 20th day of storage, showcasing specific favorable process parameters. These parameters encompass dry matter, fat, ash, proteins, water activity, pH, antioxidant potential (TP, DPPH, ABTS, FRAP), and microbiological profile. These findings offer valuable insights into producing fresh cheese efficiently with the desired quality attributes. Moreover, they highlight the effectiveness of the ANN model in optimizing diverse parameters for enhanced product development in the dairy industry

Homology modelling and docking analysis of L-lactate dehydrogenase from Streptococcus thermopilus

The aim of this research was to create a three-dimensional model of L-lactate dehydrogenase from the main yoghurt starter culture - Streptococcus thermopilus, to analyse its structural features and investigate substrate binding in the active site. NCBI BlastP was used against the Protein Data Bank database in order to identify the template for construction of homology models. Multiple sequence alignment was performed using the program MUSCULE within the UGENE 1.11.3 program. Homology models were constructed using the program Modeller v. 9.17. The obtained 3D model was verified by Ramachandran plots. Molecular docking simulations were performed using the program Surflex-Dock. The highest sequence similarity was observed with L-lactate dehydrogenase from Lactobacillus casei subsp. casei, with 69% identity. Therefore, its structure (PDB ID: 2ZQY:A) was selected as a modelling template for homology modelling. Active residues are by sequence similarity predicted: S. thermophilus - HIS181 and S. aureus - HIS179. Binding energy of pyruvate to L-lactate dehydrogenase of S. thermopilus was - 7.874 kcal/mol. Pyruvate in L-lactate dehydrogenase of S. thermopilus makes H bonds with catalytic HIS181 (1.9 Å), as well as with THR235 (3.6 Å). Although our results indicate similar position of substrates between L-lactate dehydrogenase of S. thermopilus and S. aureus, differences in substrate distances and binding energy values could influence the reaction rate. Based on these results, the L-lactate dehydrogenase model proposed here could be used as a guide for further research, such as transition states of the reaction through molecular dynamics. [Projekat Ministarstva nauke Republike Srbije, br. III 46009

The effect of processing parameters on the structure of fermented milk products with transglutaminase addition

This study is concerned with the effect of concentration of transglutaminase (TG), content of milk fat and starter culture type (probiotic and kombucha) on the structure of fermented milk products. The application of TG significantly improved textural characteristics of the fermented milk products. The firmness of the samples produced from milk with 0.1g100g-1 and 0.9g100g-1 fat content with probiotic starter were by 33% and 17.6% higher, respectively, compared to the control samples. During ten days of storage, the value of the hysteresis loop area of all samples produced from milk with 0.9g100g-1 fat content with TG addition, decreased by 14%. [Projekat Ministarstva nauke Republike Srbije, br. 46009

Influence of fat content and starter cultures on the quality of fermented dairy products

The objective of this study was to investigate the effect of fat content and type of the starter culture (traditional or probiotic) on physico-chemical quality, rheological and textural characteristics of the fermented dairy products during 14 days of storage. Seven different fermented dairy products of two different groups: stirred and set yoghurts were used in this study. The rheological and textural characteristics of the analyzed type of fermented dairy products after the production and during storage are dependent on the chemical composition, particularly fat content. [Projekat Ministarstva nauke Republike Srbije, br. III 46009

Content of sugar, organic acids and ethanol in fermented milk beverages obtained with different types of kombucha inoculum

The aim of this study was to examine the influence of different types and concentration of kombucha inoculum on content of sugar, organic acids and ethanol in the fermented beverages produced from milk of 0.9% fat content. Three different kombucha inoculums, cultivated on black tea with addition of sucrose: standard inoculum - 10% (w/w) and 15% (w/w), concentrated by microfiltration- 10% (w/w) and 15% (w/w), and concentrated by evaporation - 1.5% (w/w) and 3.0% (w/w), were applied in the manufacture of fermented milk. Contents of lactose, galactose, glucose, fructose, organic acids, and ethanol in the kombuha fermented milk beverages were determined by the enzyme tests. It was found that the lactose content varied from 3.30 to 4.0 g/100g. All samples showed higher content glucose than fructose. The content of L-lactic acid in the samples ranged from 0.4 to 0.7 g/100g, while significantly lower level of D-lactic and acetic acid were determined in all samples of kombucha fermented milk (<0.06g/100g).[Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 46009

Correlation of the microstructure with viscosity and textural properties during milk fermentation by kombucha inoculum

The aim of this study was to examine the changes in the microstructure, textural properties and viscosity of the gel formed during milk fermentation with kombucha inoculum and to establish a relationship between the microstructure and these properties. The values of the analyzed characteristics were measured during the gelation at 42°C at the following pHs: 5.4, 5.1, 4.8 and 4.6. The microstructure analysis revealed disappearance of coarse cluster structure and appearance of finer casein micelles network during fermentation. The obtained results showed significant differences in them viscosity and textural properties during fermentation, which is in accordance with their microstructure. The correlation of the examined properties and microstructure of the gel was established. [Projekat Ministarstva nauke Republike Srbije, br. 46009