Rositsa Denkova

Production of wheat bread without preservatives using sourdough starters.

In order for the beneficial effects of sourdough application in breadmaking to take place a proper selection of lactic acid bacteria species and strains, an appropriate technology and effective control of the purity and activity of the selected cultures. Four symbiotic starters for sourdough for the production of bread were developed and probated in a production laboratory using the selected strains Lactobacillus brevis LBRZ7, L. buchneri LBRZ6, L. plantarum X2, L. paracasei RN5, L. sanfranciscensis R and L. fermentum LBRH10 and the probiotic strain Propionibacterium freudenreichii ssp. shermanii NBIMCC 327. The starter sourdoughs that include Propionibacterium freudenreichii ssp. shermanii NBIMCC 327 had greater antimicrobial activity against saprophytic microorganisms: Bacillus subtilis, B. mesentericus, Aspergillus niger, Penicillium sp. and Rhizopus sp., but none of them inhibited the growth of bakery yeasts Saccharomyces cerevisiae. It was established that in order to prevent bacterial spoilage 10% of the selected starter sourdoughs had to be added in the breadmaking process, while for prevention of mold spoilage the necessary amount of starter sourdough had to be between 15% and 20%.The application of the developed starters for the production of wheat bread guarantees longer shelf life and no adverse alterations in the features of the final bread.

Examination of the technological properties of newly isolated strains of the genus Lactobacillus and possibilities for their application in the composition of starters

The ability of four Lactobacillus strains – Lactobacillus brevis LBRZ7 (isolated from fermented cabbage), Lactobacillus plantarum LBRZ12 (isolated from fermented cabbage), Lactobacillus fermentum LBRH9 (of human origin) and Lactobacillus casei ssp. rhamnosus LBRC11 (isolated from home-made cheese) – to grow in flour/water environment and to accumulate high concentrations of viable cells was examined. Two starters for sourdough were created for lab-scale production of wheat bread: a two-strain starter and a four-strain starter. Wheat bread with improved properties – greater loaf volume, enhanced flavour and softer and brighter crumb – was obtained from the 7% four-strain starter sourdough. The addition of sourdough in the production of wheat bread affected positively the technological and organoleptic characteristics of the final bread by inhibiting the growth of wild yeasts and mold and Bacillus spores without the addition of preservatives. The inclusion of 15% of the four-strain starter sourdough in the bread-making process led to enhanced safety and longer shelf life of the baked bread.

Effect of lavender (Lavandula angustifolia) and melissa (Melissa Officinalis) waste on quality and shelf life of bread

The effect of lavender (Lavandula angustifolia) and melissa (Melissa Officinalis) waste on preparation, characteristics and shelf life of bread was investigated. It was found that lavender and melissa waste, generated yearly in large amounts, were rich on polyphenols (especially rosmarinic acid) and aroma compounds, and exhibited high antioxidant and antimicrobial activity. The bread with 2.5% lavender waste was characterized with the highest loaf volume and loaf specific volume. The total dietary fiber increased three times and the polyphenols and flavonoids increased more than four times for breads with added 5% lavender and melissa waste, compared to control sample. The breads with 2.5% and 5% added lavender waste had increased shelf life (up to 96 h) compared to control, and no fungal or bacterial spoilage was observed during storage at 22 °C, 30 °C and 37 °C for four days. The sensory evaluation demonstrated that the consumers preferred mainly bread with 2.5% lavender waste.

Chemical Composition and Antimicrobial Activity of Essential Oils from Black Pepper, Cumin, Coriander and Cardamom Against Some Pathogenic Microorganisms

Abstract Four popular spices black pepper (Piper nigrum L.), cumin (Cuminum cyminum L.), coriander (Coriandrum sativum L.) and cardamom (Elettaria cardamomum) were analyzed for their oil composition by GC-MS. Thirty compounds were identified in the black pepper oil and the main components were β-caryophyllene (20.225 %), sabinene (18.054 %), limonene (16.924 %), α-pinene (9.171 %) and α-phellandrene (5.968 %). Twenty five compounds were identified in the cumin oil – cuminaldehyde (30.834 %), 3-caren-10-al (17.223 %), β-pinene (14.837 %), γ–terpinene (11.928 %), 2-caren-10-al (8.228 %) and pcymene (6.429 %). Twenty nine compounds were identified in the coriander oil – β-linalool (58.141 %), α-pinene (8.731 %), γ-terpinene (6.347 %) and p-cymene (5.227 %). Twenty nine compounds were identified in the cardamom oil – α-terpinyl acetate (39.032 %), eucalyptol (31.534 %), β-linalool (4.829 %), sabinene (4.308 %) and α-terpineol (4.127 %). The antimicrobial activity of essential oils against pathogenic (Escherichia coli ATCC 25922, Escherichia coli ATCC 8739, Salmonella sp. (clinical isolate), Staphylococcus aureus ATCC 6538P, Proteus vulgaris G) microorganisms by disc-diffusion method was examined. Gram-positive bacteria were more sensitive to the oils (inhibition zones being between 8 and 12.5 mm) and the minimum inhibitory concentration was more than 600 ppm; Gram-negative bacteria were less sensitive. The obtained essential oils are suitable for use as biopreservative agents.

Kinetics of Batch Fermentation in the Cultivation of a Probiotic Strain Lactobacillus Delbrueckii Ssp. Bulgaricus B1

Abstract A comparative study of kinetic models to describe the dynamics of the fermentation process of culturing of a probiotic strain Lactobacillus delbrueckii ssp. bulgaricus B1 was performed. The models of Monod, Aiba, Tiessier, Hinshelwood and the equation of the logistic curve combined with the model of Ludeking-Piret were used. It has been found that the different models described the observed fermentation dynamics differently. The conducted comparative study demonstrated that the models of Monod and the equation of the logistic curve combined with the model of Ludeking-Piret were suitable for the description of the fermentation dynamics. The mathematical models showed no significant product and/or substrate inhibition. The culture developed with a low specific growth rate, but nevertheless it accumulated 1012-1013 viable cells. The substrate was absorbed primarily from cells in the stationary growth phase rather than cells in the exponential growth phase

Optimization of Conditions for Obtaining Alginate/Olive Oil Capsules for Application in Dairy Industry

Abstract Encapsulation is a process of incorporation of bioactive substances in a specific matrix. It results in increasing and/or maintaining of the biological agent concentration in the food matrix or the fermentation system. The encapsulation process is influenced by various factors. The aim of the present work was to investigate the influence of alginate type and concentration, homogenization rate and the oil phase amount in the preparation of capsules rich in olive oil. It has been found that emulsions obtained with medium viscosity alginate were characterized by better stability. To establish the joint influence of the factors was used screening design experiment, the optimization features selected being temperature, centrifugal and microscopic stability. The optimal levels of the factors were established and they we applied for capsule preparation. The obtained capsules showed maximum stability and possibility to be used in dairy product manufacture.

Modeling Of Continuous Ethanol Fermentation In Ideal Mixing Column Bioreactor.

A method for formalization and analytical determination of the kinetic parameters of continuous alcohol fermentation in a reactor and in a cascade of reactors with ideal mixing was discussed in the present work. A fluidized bed bioreactor with immobilized yeast with elucidated structure of the flows was used. The method of formalization of the process kinetics involved two steps – determination of the optimal dilution rate of a continuous fermentation process, and determination of the total kinetic parameters of the cascade of reactors, including the minimum number of steps that can ensure production of maximum ethanol yield in the system.

Encapsulation of plant and animal oils used in dairy industry: A review

Abstract The development of new food products enriched with biologically active components is a topical issue for modern food science and practice. Many of these substances are unstable when being incorporated into the food matrix, which demands a study on the possibilities to stabilize them before use. Encapsulation of biologically active substances is a method which provides stability of the substance in the food product. The principles for implementing encapsulation of biologically active substances, especially natural oils, the matrices and the encapsulation methods are discussed in the present review. Data on the impact of key process parameters of encapsulation, the biological value of oils and the opportunities for application of the encapsulated systems in different groups of dairy products are presented.

Evaluation Of The Primary Metabolism Of Monocultures And Yoghurt Starters With The Participation Of Urease-Deficient Streptococcus Thermophilus Strains.

The aim of the present work was to evaluate the influence of the lack of urease activity in some Streptococcus thermophilus strains on the primary metabolism during lactic acid fermentation. A comparison of the kinetics of the lactic acid process with the participation of ureautilizing and urease deficient streptococcal strains was performed. It was found that the lack of urease activity in the streptococcal strains had no significant effect on the primary metabolism of the monocultures or the yoghurt starters.