Selection Of Starter Cultures Research Articles

Prospects for the use of probiotic microorganisms in the production of fermented buckwheat-based products

Relevance. The market segment for products based on plant-based ingredients continues to gain momentum. Protecting health and reducing the environmental burden are the most important driving forces for consumers to buy plant-based products. About 1% of the world’s population suffers from diagnosed celiac disease. Around 13% of the population exhibits symptoms of non-celiac gluten sensitivity. Thus, the production of gluten-free food products, including fermented ones, is becoming increasingly important.Methods. The technological parameters for producing buckwheat dispersion and its quality indicators were assessed. The analysis of the process of acid accumulation during fermentation by microorganisms Lactobacillus, Bifidobacterium, Propionibacterium, and Streptococcus was carried out. Data on the dynamics of microbial biomass accumulation during fermentation were obtained, and the influence of selected starter cultures on the antioxidant properties of fermented dispersions during storage was studied. The impact of chosen strains on organoleptic characteristics was determined, and the dependence of the viscosity of fermented samples on the shear rate was studied.Results. Buckwheat dispersion is a suitable medium for the production of fermented drinks. The duration of fermentation ranged from 5 to 9 hours. The most intense acid accumulation process is observed when S. thermophilus is used for 5 hours. The maximum increase in biomass is achieved with L. bulgaricus, L. acidophilus AT-41, and B. bifidum. Probiotic microorganisms provide stable levels of antioxidant activity during storage. The samples fermented with S. thermophilus, B. bifidum, P. shermanii KM-186, and L. bulgaricus were the most viscous. The most outstanding organoleptic preference was given to samples with L. acidophilus 57S, S. thermophilus, and L. bulgaricus.

Influence of Different Starter Cultures on Physical–Chemical, Microbiological, and Sensory Characteristics of Typical Italian Dry-Cured “Salame Napoli”

The selection of starter cultures with different technological profiles and suitable microclimatic conditions is among the main tools used to improve the technological quality and safety of dry-cured salami. The aim of this study is to evaluate the effect of two different starter cultures [fast (SR) and medium (SM) acidification] during the process and on the quality of typical Italian dry-cured “Salame Napoli”. The ripening process was evaluated in dry-cured salami made with different cultures: Euroferment Medium (Staphylococcus xylosus, Lactobacillus plantarum) in SM and Euroferment Rapid (Staphylococcus carnosus, Staphylococcus xylosus, Lactobacillus sakei) in SR. The salami was stuffed in artificial casings, dried for 5 days and then ripened for 28 days at a controlled temperature of 12–14 °C and 80–90% RH. During the ripening process, an evaluation of the appearance, the pH, and the weight loss of the salami were conducted. For each finished product, the physical–chemical, microbiological, rheological, and sensory characteristics were evaluated. The results showed that the different starter cultures influenced the pH descent, which was faster in SR, reaching a pH value of 4.80 in three days. This influenced the consistency profile of the SR salami, which showed higher hardness (46.04 ± 6.53 in SR vs. 35.60 ± 2.62 in SM; p < 0.05) and gumminess (19.21 ± 3.44 in SR vs. 11.89 ± 0.71 in SM; p < 0.05) values. SR salami revealed a higher count of yeasts and a lower malondialdehyde concentration than SM. The presence of the starter in SM has positively affected the intensity of the aroma. The outcomes indicated the importance of selecting starter cultures to not only ensure food safety but also to obtain the desired sensorial characteristics of the product.

Comprehensive analysis of the CRISPR-Cas systems in Streptococcus thermophilus strains isolated from traditional yogurts.

Phage resistance is crucial for lactic acid bacteria in the dairy industry. However, identifying all phages affecting these bacteria is challenging. CRISPR-Cas systems offer a resistance mechanism developed by bacteria and archaea against phages and plasmids. In this study, 11 S. thermophilus strains from traditional yogurts underwent analysis using next-generation sequencing (NGS) and bioinformatics tools. Initial characterization involved molecular ribotyping. Bioinformatics analysis of the NGS raw data revealed that all 11 strains possessed at least one CRISPR type. A total of 21 CRISPR loci were identified, belonging to CRISPR types II-A, II-C, and III-A, including 13 Type II-A, 1 Type III-C, and 7 Type III-A CRISPR types. By analyzing spacer sequences in S. thermophilus bacterial genomes and matching them with phage/plasmid genomes, notable strains emerged. SY9 showed prominence with 132 phage matches and 30 plasmid matches, followed by SY12 with 35 phage matches and 25 plasmid matches, and SY18 with 49 phage matches and 13 plasmid matches. These findings indicate the potential of S. thermophilus strains in phage/plasmid resistance for selecting starter cultures, ultimately improving the quality and quantity of dairy products. Nevertheless, further research is required to validate these results and explore the practical applications of this approach.

INVESTIGATION OF THERMOPHILIC MICROFLORA FOR THE SELECTION OF STARTER CULTURE COMPOSITION FOR A FUNCTIONAL PRODUCT

Fermented dairy products have valuable nutrients and contain a large number of living cells of lactic acid bacteria strains of lactic acid bacteria. The selection of microorganisms according to their technological and microbiological properties and their ability to develop in a dairy base, as well as organoleptic and rheological parameters of the finished fermented milk product, is an important stage in the development of new types of products. Therefore, special attention was paid to the selection of starter cultures for the production of a functional product. The authors conducted research on the selection of starter culture microflora for the production of functional products. The microbiological and organoleptic properties of selected microorganisms have been studied. When selecting microorganisms, the intensity and direction of the microbiological and biochemical processes occurring during fermentation were taken into account, which is determined by the development of the starter microflora. Thermophilic starter culture by species Lactobacillus acidophilus, Streptococcus thermophiles, Lactobacillus bulgaricus was used in the work.

Fermentation of Kalamata Natural Black Olives Using Selected Lactic Acid Bacteria as Starters

Fermented foods such as table olives are produced through a spontaneous process that has been improved over the years, ensuring the safety and quality of the final product. The aim of the present work was to study the action of starter cultures of lactic acid bacteria (Lacticaseibacillus rhamnosus GG ATCC53103, Levilactobacillus brevis ATCC8287, and Lactiplantibacillus plantarum ATCC14917) which were previously shown to have probiotic and antioxidant potential during the fermentation of natural Greek-style black olives (Kalamata) in brine containing 6% (w/v) NaCl at a temperature of 20 °C for a period of 150 days. At a molecular level, the main metabolites in every fermentation process were identified using an HPLC method. The results showed that the concentration of the metabolites increased gradually, developing a stable pattern after the 90th day of fermentation. In addition, the DL-p-hydroxyphenyllactic acid (OH-PLA) was identified as the phenolic acid with the highest concentration, independently of the selected starter culture. Microbial genomic DNA was also extracted from the olives’ surface at the final stages of fermentation (150 days) and was subjected to 16S rRNA sequencing using the Nanopore MinION™ NGS tool, enabling a comprehensive analysis of the microbial community. According to the findings, the most abundant genera were Lactobacillus and Leuconostoc. To the best of our knowledge, this is the first study exploring these particular starters for olive fermentation.

Changing some parameters in the production technology of camambre cheese

One of the exclusive European products is camembert cheese. This is a soft cheese with a current consistency, rich taste, and aroma, with a characteristic crust, on top of which the white mould Penicillium camembert grows. However, the organoleptic characteristics of the classic camembert are particular and differ from the taste habits of Russians. Russian consumers do not like too fluid cheeses and flavorful. This has caused a lot of problems with its sale. In this regard, the purpose of the research was to adjust the primary operations in the technological map related to the processing of cheese grains and moulding, as well as the selection of starter cultures. In our research, we suggest that after cutting the clot, the cheese grain should be set and the moulds filled utterly, reducing the cost of cheese moulding. The second factor that we propose is the use of domestic mesophilic starter culture MN (AltaLact). Organoleptic, physicochemical and microbiological parameters were determined in the finished cheese samples. So, the cheese taste was creamy when using the domestic starter culture MN (AltaLact) and setting the cheese grain after cutting the clot. The mushroom had no bitterness on the aftertaste and no "ammonia" taste. Using a stabilised technology, we increased the concentration of dry substances due to the production of cheese grains, which allowed us to slow down the proteolytic activity of microorganisms. Thus, the fat content in the dry matter was 59%, which is more by 2% than with traditional moulding and by 3-1% relative to the starter Danisko MM101, depending on the processing of the clot and the moulding method. The stabilised technology will increase the nutritional value by increasing the protein content in cheese; in our study, the protein content increased by 0.4 – 0.9%. Thus, the research results substantiate the practicality of making adjustments to the production technology of camembert cheese.

Features of the selection of starter cultures in the production of functional fermented milk products

Modern trends in the formation of a healthy lifestyle have led to the active development of technologies for the production of functional fermented milk products. The selection of a rational combination of lactic acid bacteria and bifidobacteria for creating starter cultures should provide products with functional properties and take into account the following criteria: the product must be safe (each microorganism included in its composition must be tested and assessed from a safety point of view, including confirmation of the absence of genes antibiotic resistance); the product must have nutritional value; the product must meet certain quantitative characteristics (amount of probiotics, acidity level, energy value). In the course of studying the features of the selection of starter cultures (lactic acid bacteria and bifidobacteria) in the production of functional fermented milk products, a search (using key words) for literature sources published between 2012 and April 2023 was carried out and related to the development of starter cultures and functional products. Using three search engines, 105 sources were selected and checked for compliance with the designated inclusion criteria. Among the selected sources, only 69 could be applicable for writing a review that has examined the effect of functional fermented milk products on the human body and has analyzed the potential of using lactic acid bacteria and bifidobacteria as a component of the starter composition.

Application of FTIR Microspectroscopy in Oenology: Shedding Light on Cell Wall Composition of Saccharomyces cerevisiae Strains

The evaluation of cell parietal components of yeasts is an important criterium for the selection of wine starters since they play a key role in the vinification process. The aim of this study was to characterize and compare the cell wall composition of four industrial (BM45, D47, EC1118, K1) and three native Saccharomyces cerevisiae (MY8, MY11, PEDRO2000E) wine strains by means of scanning and transmission electron microscopy and ATR-FTIR microspectroscopy. A statistically significant variability in the cell wall thickness and cell diameter was observed among the yeast cells, with native strains showing higher cell diameter values. FTIR microspectroscopy applied on the intact cells without any previous invasive treatment and on the separated cell walls highlighted profound differences among the strains in terms of the overall content of parietal polysaccharides as related to the thickness of the cell walls and in terms of the relative concentration of β-glucans and mannans in the cell walls. The strains EC1118, MY11, and PEDRO2000E showed a higher overall content of β-glucans and mannans, whose lower relative concentration in PEDRO2000E was compensated by a thicker cell wall; BM45 and D47 were characterized by a high relative concentration of polysaccharides in a thinner wall, while K1 and MY8 displayed a low relative concentration of polysaccharides. ATR-FTIR microspectroscopy allows identifying polysaccharide-rich yeast strains and can become a smart option for the selection of starter cultures to be used in oenology and for other applications in food industry, thanks to the interesting technological properties of parietal polysaccharides.Graphical

On the Molecular Selection of Exopolysaccharide-Producing Lactic Acid Bacteria from Indigenous Fermented Plant-Based Foods and Further Fine Chemical Characterization.

Exopolysaccharides (EPSs) produced by lactic acid bacteria present a particular interest for the food industry since they can be incorporated in foods via in situ production by selected starter cultures or applied as natural additives to improve the quality of various food products. In the present study, 43 strains were isolated from different plant-based fermented foods and identified by molecular methods. The species found were distinctively specific according to the food source. Only six Lactiplantibacillus plantarum strains, all isolated from sauerkraut, showed the ability to produce exopolysaccharide (EPS). The utilization of glucose, fructose and sucrose was explored with regard to EPS and biomass accumulation by the tested strains. Sucrose was clearly the best carbon source for EPS production by most of the strains, yielding up to 211.53 mg/L by strain Lactiplantibacillus plantarum ZE2, while biomass accumulation reached the highest levels in the glucose-based culture medium. Most strains produced similar levels of EPS with glucose and fructose, while fructose was utilized more poorly for biomass production, yielding about 50% of biomass compared to glucose for most strains. Composition analysis of the EPSs produced by strain Lactiplantibacillus plantarum ZE2 from glucose (EPS-1) and fructose (EPS-2) revealed that glucose (80-83 mol%) and protein (41% w/w) predominated in both analyzed EPSs. However, the yield of EPS-1 was twice higher than that of EPS-2, and differences in the levels of all detected sugars were found, which shows that even for the same strain, EPS yield and composition vary depending on the carbon source. These results may be the basis for the development of tailored EPS-producing starter cultures for food fermentations, as well as technologies for the production of EPS for various applications.

Подбор заквасочных культур для производства ферментированного молочно-зернового продукта детского питания

Одно из направлений обогащения молочных продуктов биологически активными веществами, расширения ассортимента и экономии основного сырья – использование растительных ингредиентов при их производстве. Создание продуктов питания с повышенной биологической активностью, способствующих укреплению защитных функций организма и нейтрализующих действие окружающей среды, особенно важно в современных условиях, характеризующихся ухудшением экологической обстановки, техногенными аномалиями, увеличением частоты стрессовых ситуаций и другими факторами. Использование полезных качеств молочных и зерновых продуктов в сочетании позволяет получать гармоничные по составу и свойствам композиты. Молочно-зерновые продукты обладают функциональными свойствами. В их комбинациях содержатся кальций и белок, богатый незаменимыми аминокислотами (в молочном ингредиенте), полиненасыщенные жирные кислоты (растительный жир злакового ингредиента), пищевые волокна (плодовые и семенные оболочки злаков), витамины (С, В1, В2, В6, Е, каротин), в том числе антиоксиданты (Е, бета-каротин), олигосахариды и минеральные вещества [1]. Учитывая довольно широкий ассортимент подобных продуктов, их достаточную изученность, наибольший интерес в проведении настоящих исследований вызывает создание многокомпонентных кисломолочных продуктов на основе комбинации молока различных видов сельскохозяйственных животных с использованием сочетания муки трех видов зерновых культур. Данное направление является весьма перспективным в плане разработки технологии кисломолочных продуктов для питания детей старше трех лет. На фоне борьбы с последствиями COVID-19 актуализируется роль пробиотиков и пребиотиков в формировании иммунитета. Особенный интерес к кисломолочным напиткам с пробиотическими свойствами обусловлен тем, что микроорганизмы, содержащиеся в них, созданы самой природой и выполняют защитную функцию в биологическом организме. Актуален подход к обогащению кисломолочных напитков лактокультурами L. Casei, L. Rhamnosus и L. Acidophilus [2, 3]. В рамках научно-исследовательской работы проведена выработка многокомпонентных продуктов на молочной основе с двумя видами молока (коровьим и козьим), с добавлением различных комбинаций муки зерновых культур (овсяной, рисовой и льняной). Была проведена органолептическая оценка образцов ферментированных продуктов с различными видами закваски молочнокислых бактерий. One of the directions of enriching dairy products with biologically active substances, expanding the assortment and saving the main raw materials is the use of vegetable ingredients in their production. The creation of food products with increased biological activity that strengthen the protective functions of the body and neutralize the effects of the environment is especially important in modern conditions characterized by environmental degradation, man-made anomalies, an increase in the frequency of stressful situations and other factors. The use of the beneficial qualities of dairy and grain products in combination makes it possible to obtain composites that are harmonious in composition and properties. Dairy and grain products have functional properties. Their combinations contain: calcium and protein rich in essential amino acids (in the milk ingredient), polyunsaturated fatty acids (vegetable fat of the cereal ingredient), dietary fiber (fruit and seed shells of cereals), vitamins (C, B1, B2, B6, E, carotene), including antioxidants (E, beta-carotene), oligosaccharides and minerals [1]. Given a fairly wide range of such products, their sufficient knowledge, the greatest interest in conducting these studies is the creation of multicomponent fermented milk products based on a combination of milk of various types of farm animals using a combination of flour of three types of cereals. This direction is very promising in terms of developing the technology of fermented milk products for the nutrition of children over three years old. Against the background of the fight against the consequences of COVID-19, the role of probiotics and prebiotics in the formation of immunity is being updated. Particular interest in fermented milk drinks with probiotic properties is due to the fact that the microorganisms contained in them are created by nature itself and perform a protective function in the biological organism. An approach to the enrichment of fermented milk drinks, lacto-cultures of L. Casei, L. Rhamnosus and L. acidophilus is relevant [2, 3]. As part of the research work, the development of multicomponent fermented milk products based on milk with two types of cow's and goat's milk, with the addition of various combinations of grain flour, was carried out. Organoleptic evaluation of samples of lactic acid cultures fermented with various types of starter culture was carried out.

Characteristics of lactose-free/low-lactose fermented dairy products containing microorganisms that are part of the kefir grain consortium: Scoping review

Introduction: There are a significant number of scientific publications dedicated to the analysis of lactose-free and low-lactose fermented milk products, primarily in the context of studying specific microorganisms or starter cultures and their functioning under conditions of limited lactose content. Nevertheless, the synthesis of accumulated data has not been sufficiently highlighted, considering that a large part of the research was conducted over the past 10 years, and an intensive examination of this issue has only begun in the recent past.Purpose: To systematically and critically analyze scientific research that sheds light on the specifics of fermented milk products with a reduced lactose level, focusing on a comparative study of standard fermented milk products and their low-lactose or lactose-free modifications. Special attention is paid to fermented milk products containing microorganisms that are part of the kefir fungus consortium.Materials and Methods: Sources for the review were selected from the Scopus, ScienceDirect, RISC (Russian Index of Science Citation), and Google Scholar databases. Out of 208 publications relevant in terms of keywords, 34 were selected for analysis. The main criterion for selecting articles was a description in them of studies on the use of low-lactose or lactose-free milk as a medium for cultivating starter cultures. This review of the subject area is based on the PRISMA-ScR protocol.Results: Many scientific studies indicate that the prepared low-lactose or lactose-free fermented milk products exhibited similar or improved physicochemical and organoleptic characteristics compared to standard fermented milk products. In experiments aimed at evaluating microbiological characteristics, it was observed that the concentration of lactic acid bacteria in the analyzed products either matched, was lower, or was higher than in traditional fermented milk products. In some publications, scientists found that the final fermented milk product had deteriorated organoleptic and physicochemical parameters. However, all reviewed low-lactose or lactose-free fermented milk products met the standards and regulatory requirements of the countries in which the respective research was conducted.Conclusion: The development of low-lactose and lactose-free fermented milk products is a relevant direction in the food industry, considering their similarity to conventional products and adaptability for consumption by individuals with varying degrees of lactose intolerance. There are nuances related to the duration of the fermentation process, organoleptic characteristics, acidity level, syneresis, preservation, and growth dynamics of microorganisms. These features can be dictated by specific strains of microflora used in the starter and, most often, their influence remains minimal. The results obtained in this study may be useful for selecting starter cultures when designing various fermented milk products, including yogurt, fortified yogurt, kefir, ayran, ryazhenka, and acidophilus. For a deeper understanding of the interaction of the modified glucose-galactose medium with various strains and species of lactic acid bacteria, further experimental work is needed, considering that the activity of these bacteria directly determines the quality characteristics of the final fermented milk product.

Effect of Flax Cake and Lupine Flour Addition on the Physicochemical, Sensory Properties, and Composition of Wheat Bread

Bread is consumed by people all over the world. Its quality may be modified by the application of other raw materials or changes in production technology. The addition of flax cake (FC) and lupine flour (LF) was proposed as a modification of the nutritional value of wheat bread. Bread with non-fermented and fermented FC and LF was prepared, and its physicochemical, sensory properties and composition were compared to wheat bread. A higher than 5% addition of these components reduced the bread volume and increased their hardness, gumminess, and chewiness. To reduce the negative impact of these additives on the physical and sensory properties of bread, these raw materials were fermented by selected starter cultures. The addition of FC and LF fermented by Lactobacillus plantarum lowered the undesirable changes in the physicochemical properties of the bread. It also slightly increased the overall acceptability of the products. Propionic fermentation lowered sensory assessment rates considerably. The following changes in the composition of bread prepared with the addition of fermented by L. plantarum FC and LF were noted: increase in protein (by ~30%), ash (by ~100%), both soluble and insoluble fiber (by ~500%) content. The starch content was reduced by about 18–20%. The modifications increased the nutritional value of the obtained bread, preserving its physicochemical properties and sensory acceptability.

Antimicrobial Resistance of Lactic Acid Bacteria from Nono, a Naturally Fermented Milk Product.

Antimicrobial resistance (AMR) is one of the biggest threats to public health. The food chain has been recognised as a vehicle for transmitting AMR bacteria. However, information about resistant strains isolated from African traditional fermented foods remains limited. Nono is a traditional, naturally fermented milk product consumed by many pastoral communities across West Africa. The main aim of this study was to investigate and determine the AMR patterns of lactic acid bacteria (LAB) involved in the traditional fermentation of milk for Nono production, and the presence of transferable AMR determinants. One hundred (100) LAB isolates from Nono identified in a previous study as Limosilactobacillus fermentum, Lactobacillus delbrueckii, Streptococcus thermophilus, Streptococcus infantarius, Lentilactobacillus senioris, Leuconostoc pseudomesenteriodes, and Enterococcus thailandicus were investigated. The minimum inhibitory concentration (MIC) was determined for 18 antimicrobials using the micro-broth dilution method. In addition, LAB isolates were screened for 28 antimicrobial resistance genes using PCR. The ability of LAB isolates to transfer tetracycline and streptomycin resistance genes to Enterococcus faecalis was also investigated. The experiments revealed variable antimicrobial susceptibility according to the LAB isolate and the antimicrobial tested. The tetracycline resistance genes tet(S) and tet(M) were detected in isolates Ent. thailandicus 52 and S. infantarius 10. Additionally, aad(E) encoding resistance to streptomycin was detected in Ent. thailandicus 52. The conjugation experiments suggested that the tet(S) and aad(E) genes were transferable in vitro from isolate Ent. thailandicus 52 to Ent. faecalis JH2-2. Traditional fermented foods play a significant role in the diet of millions of people in Africa, yet their contribution to the burden of AMR is largely unknown. This study highlights that LAB involved in traditionally fermented foods could be potential reservoirs of AMR. It also underscores the relevant safety issues of Ent. thailandicus 52 and S. infantarius 10 for use as starter cultures as they carry transferable AMR genes. Starter cultures are an essential aspect of improving the safety and quality attributes of African fermented foods. However, AMR monitoring is an important safety aspect in the selection of starter cultures for improving traditional fermentation technologies.

Impact of starter culture on biochemical properties of sourdough bread related to composition and macronutrient digestibility

Due to the desire for nutritionally dense foods, there is interest in whole grain and sourdough bread products. This research study was carried out to evaluate the effect of different starter cultures and stone mill settings on the nutritional attributes of sourdough bread. Using a stone mill, a blend of three hard red spring wheat varieties was ground into whole-grain flour. Three different gap settings and two different rotation speed values were used to produce flour samples with six different treatments, and those six flour samples were used to make sourdough bread with two different starter cultures. The experimental design was a randomized complete block design with a factorial arrangement. Significant differences (p < 0.05) were observed in dietary fiber content, arabinoxylan content, total starch content, and protein digestibility between sourdough bread made with rye and wheat starter cultures. Higher protein digestibility values were observed for most of the sourdough samples with the rye starter culture compared to the wheat starter culture. In addition, the protein digestibility showed a strong negative correlation (r = −0.85) with the coarse particles and a positive correlation (r = 0.70) with the fine particle size fraction. These results demonstrated that selected starter cultures and the raw material with the desired particle size could improve sourdough bread's nutritional attributes and potential application in the baking industry.

Comparing Spanish-Style and Natural Fermentation Methods to Valorise Carolea, Nocellara Messinese and Leccino as Table Olives

This paper presents the results of the transformation into table olives of drupes belonging to three Italian cultivars: Carolea, Leccino and Nocellara Messinese, widely used for virgin olive oil production, by using the two most common methods to produce fermented table olives: the Spanish-style method (SS) and the natural fermentation (NF). The most suitable drupes as table olives due to their flesh-to-pit ratio and high-weight fruits were Nocellara Messinese olives. From the results obtained, it was highlighted that fermentation must be improved by using a selected starter culture that can drive the fermentation by rapid acidification. In fact, the long time required by NF results in a lower pH close to the hygienic safety limit but not low enough to be considered as a stable product, while the fast fermentation obtained by treating the olives with lye solution resulted in pH values that were too high. The sugar content in all table olives was almost null, and the sensory evaluation showed that SS olives were less bitter than NF olives. Moreover, NF olive-flesh samples showed a higher amount of healthy phenolic compounds than SS olives, whose phenolic content was drastically affected by the alkaline treatment and the successive washing steps.

УДОСКОНАЛЕННЯ ТЕХНОЛОГІЇ ПОСІЧЕНИХ НАПІВФАБРИКАТІВ З ВИКОРИСТАННЯМ СТАРТОВИХ КУЛЬТУР

Characteristics of starter cultures for the production of chopped semi-finished products Antimicrobial activity of selected starter cultures against food pathogens

Aroma profiles of sweet cherry juice fermented by different lactic acid bacteria determined through integrated analysis of electronic nose and gas chromatography-ion mobility spectrometry.

Sweet cherries are popular among consumers, with a recent explosion in sweet cherry production in China. However, the fragility of these fruits poses a challenge for expanding production and transport. With the aim of expanding the product categories of sweet cherries that can bypass these challenges, in this study, we prepared sweet cherry juice fermented by three different lactic acid bacteria (LAB; Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus rhamnosus GG), and evaluated the growth, physiochemical, and aroma characteristics. All three strains exhibited excellent growth potential in the sweet cherry juice; however, Lactobacillus acidophilus and Lactobacillus plantarum demonstrated more robust acid production capacity and higher microbial viability than Lactobacillus rhamnosus GG. Lactic acid was the primary fermentation product, and malic acid was significantly metabolized by LAB, indicating a transition in microbial metabolism from using carbohydrates to organic acids. The aroma profile was identified through integrated analysis of electronic nose (E-nose) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) data. A total of 50 volatile compounds characterized the aromatic profiles of the fermented juices by HS-GC-IMS. The flavor of sweet cherry juice changed after LAB fermentation and the fruity odor decreased overall. Lactobacillus acidophilus and Lactobacillus plantarum significantly increased 2-heptanone, ethyl acetate, and acetone contents, bringing about a creamy and rummy-like favor, whereas Lactobacillus rhamnosus GG significantly increased 2-heptanone, 3-hydroxybutan-2-one, and 2-pentanone contents, generating cheesy and buttery-like odors. Principal component analysis of GC-IMS data and linear discriminant analysis of E-nose results could effectively differentiate non-fermented sweet cherry juice and the sweet cherry juice separately inoculated with different LAB strains. Furthermore, there was a high correlation between the E-nose and GC-IMS results, providing a theoretical basis to identify different sweet cherry juice formulations and appropriate starter culture selection for fermentation. This study enables more extensive utilization of sweet cherry in the food industry and helps to improve the flavor of sweet cherry products.

Design and Volatile Compound Profiling of Starter Cultures for Yogurt Preparation.

Stable symbiotic starter cultures were created using selected strains of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus with antimicrobial activity against pathogens and necessary antibiotic sensitivity, growth kinetic parameters, and metabolic profiles. The volatile compound profiles of the obtained starter cultures were determined and their specificity was proven depending on the ratio of monocultures in each combination. The influence of the freeze-drying process on the starter cultures in relation to the production of aromatic components was investigated and it was demonstrated that this process had a significant effect on the content of the aroma-forming substances in the fermented milk. However, the influence of the pre-cooling process and crude fat content from 1.5 to 3.0% did not notably affect the levels of volatile compounds synthesized by the selected starter cultures. Comprehensive data for all volatile aromatic metabolites in the fermented milk were also obtained. These designed symbiotic starter cultures can be used to produce traditional Bulgarian yogurt with increased functional and probiotic properties.

Effect of a Selected Protective Culture of Lactilactobacillus sakei on the Evolution of Volatile Compounds and on the Final Sensorial Characteristics of Traditional Dry-Cured Fermented "Salchichón".

In this work, the effect of a selected starter culture of Lactilactobacillus sakei 205 on the evolution of volatile compounds throughout the ripening process and on the final sensorial characteristics of traditional dry-cured fermented "salchichón" was evaluated. "Salchichón" sausages were prepared, inoculated with L. sakei 205, and ripened for 90 days. Volatile compounds were analyzed throughout the ripening by GC-MS. In the final product, instrumental texture and color were determined. In addition, sensorial analysis was performed by a semi-trained panel. The inoculation of L. sakei 205 does not influence the texture and color parameters of ripened "salchichón". However, an increase in volatile compounds derived from amino acid catabolism and microbial esterification and a decrease in compounds derived from lipid oxidation, mainly hexanal, were observed throughout the ripening time as a consequence of L. sakei inoculation, which could have a positive effect on the flavor development of the dry-cured fermented "salchichón". The use of selected strains of lactic acid bacteria (LAB) such as L. sakei 205 as a protective culture could be recommended to improve the quality of traditional "salchichón".

Conversion of hydroxycinnamic acids by Furfurilactobacillus milii in sorghum fermentations: Impact on profile of phenolic compounds in sorghum and on ecological fitness of Ff. milii.

The conversion of phenolic compounds by lactobacilli in food fermentations contributes to food quality. The metabolism of phenolics by lactobacilli has been elucidated in the past years but information on the contribution of specific enzymes in food fermentations remains scarce. This study aimed to address this gap by disruption of genes coding for the hydroxycimmanic acid reductase Par1, the hydroxycinnamic acid decarboxylase Pad, the hydrocinnamic esterase EstR, and strains with disruption of all three genes in Furfurilactobacillus milii FUA3583. The conversion of phenolics by Ff. milii and its isogenic mutants in sorghum fermentations was studied by LC-UV and LC-UV-MS/MS analyses. Ff. milii FUA3583 converted hydroxycinnamic acids predominantly with Par1. Vinylphenols were detected only in mutants lacking par1. A phenotype for the estR defective mutant was not identified. The formation of pyrano-3-deoxyanthocyanidins was observed only after fermentation with strains expressing Pad. Specifically, formation of these compounds was low with Ff. milii FUA3583, substantially increased in the Par1 mutant and abolished in all mutants with disrupted pad. Competition experiments with Ff. milii FUA3583 and its isogenic mutants demonstrated that expression of one of the two metabolic pathways for hydroxycinnamic acids increases the ecological fitness of the strain. Disruption of EstR in a Δpar1Δpar2Δpad background improved ecological fitness, indirectly demonstrating a phenotype of the esterase in Ff. milii. The documentation of the functionality of genes coding for conversion of hydroxycinnamic acids may support the selection of starter cultures for improved quality of fermented cereal products.