Traditional Yogurt Research Articles

Karotin contained bioyogurts and their use for the development of biologically valuable restaurant dishes

The paper considers the feasibility of using organic yogurts in the manufacture of several traditional cold dishes, in the recipes of which there is a fermented milk product. We studied the experience of scientists in improving the quality of food and increasing their biological value through the addition of functional plant materials. The authors of the article described the results of optimization of several dishes of different cuisines of the world, which use sour milk component in their recipes. An appropriate substitute with improved characteristics is proposed and the use of organic yogurt with amaranth extract as a biologically valuable component of updated recipes is justified. The aim of the work was to improve the technology of cooking Greek, Spanish, Turkish and Bulgarian cuisines with partial replacement of traditional recipe ingredients. The research was conducted on the basis of the Department of Hotel and Restaurant Business and Food Technologies of Ivan Franko Lviv National University. The raw materials used met the quality and safety requirements of current regulations. The use of amaranth extract in the production of yogurt leads to increased viscosity and improved product structural and organoleptic properties. The use of amaranth in various dishes provides them with an additional number of useful components, including carotene-containing compounds, proteins, micro- and macronutrients, etc. This increases the biological value of the product and products using it. Dishes developed with the replacement of traditional yogurts with bioanalogues with amaranth are characterized by better organoleptic evaluations, consumer performance, and health properties. The presence of amaranth adds a subtle nutty note, enriching the taste of the finished dish.

Lactobacilli isolates as potential aroma producer starter cultures: Effects on the chemical, physical, microbial, and sensory properties of yogurt

Five lactobacilli isolates from traditional yogurts and a commercial isolate (LB) were utilized for yogurt production and weekly chemical, physical, microbial, and sensory analyzes were performed during the 21-day storage period. All yogurt samples possessed similar gross compositions, and no significant difference was detected between yogurt samples in terms of acidity and syneresis rates, together with lactobacilli and streptococci counts during storage (p > 0.05). All samples exhibited pseudoplastic behavior and solid-like properties. The highest complex and apparent viscosity values were determined in LB, KKC2, and EPSC2 yogurts. The EPSC2 strain has stood out, leaving the commercial culture behind, regarding acetaldehyde and acetone production while CBH4 and CBX have fallen behind others considering sensory and aromatic properties. Except for viscosity, EPSC2 and KKC2 exhibited similar or better characteristics, including sensory properties and flavor profiles, than LB. In conclusion, EPSC2 and KKC2 are recommended as potential yogurt starters.

Effect of mixed banana and papaya peel pectin on chemical compositions and storage stability of Ethiopian traditional yoghurt (ergo)

The massive potential of hydrocolloids related to the storage stability of yoghurt is evident for the development of stabilising agents. In this context, the present study investigated the influence of mixed banana-papaya peel pectin on the chemical composition and storage stability of yoghurt. Chemical composition and physicochemical characterisation of fresh and pectin added yoghurt samples were analysed by Lacto scan. The effect of yoghurt volume, storage period, and pectin amount on the storage stability was analysed using Design-Expert Software 11. Minimum whey layer (showing high stability) was found at the optimised conditions of pectin (0.06 g), yoghurt (45 mL), and storage period (7 days) with a value of 1.2%. Also, the present study revealed that pectin improves the sensory properties and general acceptance of yoghurt. Furthermore, the microbial load (total plate count) was found to increase with increased pectin amount.

Lacticaseibacillus rhamnosus FM9 and Limosilactobacillus fermentum Y57 Are as Effective as Statins at Improving Blood Lipid Profile in High Cholesterol, High-Fat Diet Model in Male Wistar Rats.

Elevated serum cholesterol is a major risk factor for coronary heart diseases. Some Lactobacillus strains with cholesterol-lowering potential have been isolated from artisanal food products. The purpose of this study was to isolate probiotic Lactobacillus strains from traditional yoghurt (dahi) and yogurt milk (lassi) and investigate the impact of these strains on the blood lipid profile and anti-obesity effect in a high cholesterol high fat diet model in Wistar rats. Eight candidate probiotic strains were chosen based on in vitro probiotic features and cholesterol reduction ability. By 16S rDNA sequencing, these strains were identified as Limosilactibacillus fermentum FM6, L. fermentum FM16, L. fermentum FM12, Lacticaseibacillus rhamnosus FM9, L. fermentum Y55, L. fermentum Y57, L. rhamnosus Y59, and L. fermentum Y63. The safety of these strains was investigated by feeding 2 × 108 CFU/mL in saline water for 28 days in a Wistar rat model. No bacterial translocation or any other adverse effects were observed in animals after administration of strains in water, which indicates the safety of strains. The cholesterol-lowering profile of these probiotics was evaluated in male Wistar rats using a high-fat, high-cholesterol diet (HFCD) model. For 30 days, animals were fed probiotic strains in water with 2 × 108 CFU/mL/rat/day, in addition to a high fat, high cholesterol diet. The cholesterol-lowering effects of various probiotic strains were compared to those of statin. All strains showed improvement in total cholesterol, LDL, HDL, triglycerides, and weight gain. Serum cholesterol levels were reduced by 9% and 8% for L. rhamnosus FM9 and L. fermentum Y57, respectively, compared to 5% for the statin-treated group. HDL levels significantly improved by 46 and 44% for L. rhamnosus FM9 and L. fermentum Y57, respectively, compared to 46% for the statin-treated group. Compared to the statin-treated group, FM9 and Y57 significantly reduced LDL levels by almost twofold. These findings show that these strains can improve blood lipid profiles as effectively as statins in male Wistar rats. Furthermore, probiotic-fed groups helped weight control in animals on HFCD, indicating the possible anti-obesity potential of these strains. These strains can be used to develop food products and supplements to treat ischemic heart diseases and weight management. Clinical trials, however, are required to validate these findings.

Greek vs traditional yogurts: Sensory and physicochemical comparison

Greek vs traditional yogurts: Sensory and physicochemical comparison

Comparison Of Efficacy Of Yogurt Versus Probiotics For The Management Of Acute Diarrhoea.

The advantages of probiotic administration for acute diarrhoea are mainly shorter duration of symptoms as well as reduced number of stools per day while use of traditional yogurt has similar results. So, this study was conducted to compare the efficacy of yogurt with probiotic in children with acute gastroenteritis. This randomized controlled trial was conducted at department of Paediatrics, Children Hospital, Pakistan Institute of Medical Sciences, Islamabad over 1 year. A total of nine hundred and thirty (930) children between 1-5 years of age presenting with acute diarrhoea were enrolled and equally randomized to Group-A (yogurt) and Group-B (lactobacillus rhamnosus) with ORS. The primary outcome was mean frequency of diarrhoea in first 24 hours after initiation of treatment in both the groups. Gender distribution revealed that out of 930 patients, 643 (69.1%) were male and 287 (30.9%) were female while the mean age was 3.14±1.18 years. Mean duration of disease was 4.23±2.02 days. Mean no. of stools in first 24 hours after treatment in Group-A (yogurt) was 3.25±1.64 and 3.29±1.74 in Group-B (probiotics). Student t-test for independent samples was applied and no significant difference was found between the two groups (p=0.713). Mean frequency of diarrhoea in first 24 hours after treatment with traditional yogurt and commercially available probiotics was not statistically significant in this study.

The impact of tarragon essential oil on the activity of starter bacteria, molds and yeasts and the improvement of the properties of traditional yogurt

The impact of tarragon essential oil on the activity of starter bacteria, molds and yeasts and the improvement of the properties of traditional yogurt

Probiotic Properties of Lactic Acid Bacteria Isolated from Traditional Yoghurt (Dahi) in Sindh Pakistan

The probiotic properties of Lactobacillus isolates of traditional yoghurt were investigated during the study. For that seven species of Lactobacillus were identified phenotypically. Out of 84 isolates, 23 acidophilus, 21 L. casei, 11 L. helveticus, 09 each L. delbrueckii sub sp. bulgaricus and L. delbrueckii sub sp. lactis, 03 L. viridescense and 02 L. plantarum were identified. All of these identified species were screened for antibacterial activity against foodborne pathogens, acid and bile tolerance and antibiotic resistance pattern. The results indicated that L. casei S66, L. delbrueckii sub sp. bulgaricus S65, L. acidophilus S26 and L. plantarum S19 produced antimicrobial substances against the indicator organisms and showed tolerance against acidic pH of 2.5 and survival against the bile salt concentration of 0.1 and 0.2. The L. acidophilus S26 survived the 0.3% bile salt concentration and was resistant to antibiotics ciprofloxacin, kanamycin, penicillin and vancomycin.

Bioactivity, Physicochemical and Sensory Properties of Probiotic Yoghurt Made from Whole Milk Powder Reconstituted in Aqueous Fennel Extract

Fermented dairy products have long been associated with positive health benefits. The present study was undertaken to evaluate the physicochemical and sensory properties, viable probiotic counts, antioxidant activity and total phenolic content of probiotic yoghurt made by reconstituting of whole milk powder in aqueous fennel seed extract. Different concentrations of fennel aqueous seeds extract (2%, 4% and 6% w/v) were used as a substitute for water to reconstitute whole milk powder in formulations of yoghurt as functional additives. Interestingly, the use of aqueous extract of fennel seeds in the reconstituted yoghurt milk did not affect yoghurt composition (moisture, protein, fat and ash contents) compared to plain yoghurt. The titratable acidity significantly decreased after using aqueous fennel seed extract in the yogurt manufacture. In this regard, the titratable acidity value was 0.85 in the control yogurt at the fresh period and 1.14 after 21 days of storage, while this value significantly decreased in the yogurt treatments with 2%, 4% and 6% aqueous fennel seed extract to 80, 0.77 and 0.72, respectively, at fresh period and reached 1.03, 0.96 and 0.94, respectively, after 21 days of storage (p < 0.05). Conversely, the pH values significantly increased (p < 0.05) following the addition of aqueous fennel seed extract in the yogurt manufacture. Moreover, the total phenolic content significantly increased (p < 0.05) from 38.60 (mg GAE/L), in fresh plain yogurt, to 44.80, 53.20 and 64.30 (mg GAE/L), in 2% fennel extract yoghurt (FEY2), 4% fennel extract yoghurt (FEY4) and 6% fennel extract yoghurt (FEY6), respectively. Likewise, the antioxidant activity significantly increased (p < 0.05) from 0.11 (mM TE) in fresh plain yogurt to 0.18, 0.26 and 0.32 (mM TE) in (FEY2), (FEY4) and (FEY6), respectively. The survival of Lactobacillus acidophilus, Streptococcus thermophilus and Bifidobacterium bifidum decreased during storage time in all yoghurt treatments, although it stood at recommended levels for health effects (at least 106 cfu/mL in traditional yoghurt). For sensory evaluation, FEY4 was more acceptable, followed by FEY6, FEY2 and PY, respectively. Collectively, the present study provides useful information about the bioactivity, physicochemical and sensory properties of probiotic yoghurt made from whole milk powder reconstituted in aqueous fennel extract.

Evaluation of quality indicators of fermented milk product based on sheep’s milk enriched with vegetable ingredients

The purpose of this study is a comprehensive assessment of the quality of yogurt enriched with vegetable ingredients. The object of research is a fermented milk product, the main ingredient of the formulation is sheep’s milk. The unique composition of sheep’s milk makes it a promising raw material for obtaining food products with high biological and nutritional value. Milk thistle meal, ground walnut and chokeberry syrup were selected as vegetable fortifiers for the yogurt under study. Experimental studies were conducted in the Don State Agrarian University. Traditional yogurt based on cow’s milk without fillers was selected as control samples. When analyzing the results of studies of the fatty acid composition of the samples of the fermented milk product, it was revealed that the prototype in terms of the content of some fatty acids exceeds the values of the control, due to the replacement of cow’s milk and the introduction of vegetable ingredients. The study assessed the quality indicators of yogurt samples, such as organoleptic, physico-chemical, biochemical and microbiological. Based on the results obtained, it can be concluded that it is advisable to enrich the fermented milk product with vegetable ingredients.

Effects of cultivation conditions on biofortification of yogurt with natural folate by Propionibacterium freudenreichii

In this study, Propionibacterium (P.) freudenreichii was used for the folate production by co-culturing with traditional yogurt starter cultures in synbiotic yogurt and then it was compared to control yogurt containing only LAB starters. First, effects of process variables, including two probiotic strains, inoculum size, inulin concentration, milk fat percentage, sunflower oil content, fermentation temperature and storage time of incubation at 4 °C on folate production by P. freudenreichii were investigated using screening method of Plackett-Burman design. Then, optimization of folate production process was carried out using three main effects of inulin concentration, fermentation temperature and storage time at 4 °C using central composite design. Analysis of variance showed that the models were highly significant (p ≤ 0.05) and folate production affected by the three factors. Optimized folate production by P. freudenreichii ssp. shermanii in yogurts was achieved after 12 d of storage at 4 °C in 2% (w/v) skim-milk inulin as prebiotic and fermentation temperature of 38.6 °C. Reconfirmation assays showed that the highest produced folate included 39.2 ± 0.7 μg 100 mL-1 in FW yogurt containing P. freudenreichii ssp. shermanii under the highlighted optimum conditions, which increased by 49% of the total folate production, compared to control yogurt, which contained only LAB starters. Furthermore, textural properties were assessed using texture analysis. Coculture of P. freudenreichii with traditional yogurt starter culture and addition of inulin to yogurt samples increased hardness, consistency and cohesiveness values in yogurt samples. Results showed that by co-culturing of P. freudenreichii ssp. shermanii in yogurt, in addition to producing a probiotic product, also increases the amount of folate production compared to control yogurt, which contained only LAB starters.

Antimicrobial activity of bacteriocin produced by a new Latilactobacillus curvatus sp.LAB-3H isolated from traditional yogurt.

In recent years, the use of bacteriocin-producing Lactobacillus species has received much attention in different areas, including using as probiotics, food preservation, and as broad antimicrobial spectrum activity. In this study, a bacteriocin-producingLactobacillusstrain was isolated from traditional yogurt. The isolate was identified by morphological, biochemical, 16S rRNA analyses, and designated asLatilactobacillus curvatusLAB-3H. The primary antimicrobial activity of the isolate was evaluated onMicrococcus luteusPTCC 1408 by the agar gel diffusion method. The growth ofL. curvatusLAB-3H in MRS broth at 37°C and its antimicrobial activity againstLactobacillus caseiATCC 39,392 was evaluated. In batch culture analysis, bacteriocin production starts at the early exponential growth phase and continues to the middle of the stationary phase about (660 AU/ml) at 28h and pH 3.8. Bacteriocin produced byL. curvatusLAB-3H showed antibacterial activity against some selected foodborne pathogens, includingListeria monocytogenesPTCC1294,Bacillus cereusPTCC1857,Staphylococcus aureusPTCC1917, andEscherichia coliPTCC1276. For purification of bacteriocin, ammonium sulfate precipitation and cation exchange chromatography methods were used. The maximum antimicrobial activity observed was about 3985.15 AU/mg of protein, which was a 249.22-fold increase, and 5.21% yield compared with that in the cell-free supernatant. The molecular weight of bacteriocin was approximately 55kDa by SDS-PAGE. The obtained results in this study demonstrate that bacteriocin fromL. curvatusLAB-3H is a potential candidate for controlling microbial contaminations and can be used in different sectors, such as food industries.

The use of the strain Enterococcus faecium in the technology of yogurt “Carpathian” as an ancillary culture with probiotic properties

The results of research on the technological features of the production of yogurt "Carpathian" are covered in the article. The bacterial preparation of Chr. Hansen series YoFlex Premium 1.0 (L. bulgaricus, S. thermophilus) and Creamy 1.0 (L. bulgaricus, S. thermophilus, L. rhamnosus) and strain E. faecium SB 18, which is isolated from traditional Carpathian fermented products were used to produce research yogurt samples. It was found that when the strains were used together, the microorganisms were compatible, did not show interspecific antagonism and did not inhibit the enzymatic process. Based on yogurt microorganisms and E. faecium SB 18 strain, seven prototypes of yogurt were created: № 1 (100 %) – control, Premium + Creamy; № 2 (100 %) – control, pure culture of E. faecium SB 18; №3 (100:100 %) – control, (Premium + Creamy) + E. faecium SB 18; №4 (50:50 %) – (Premium + Creamy) + Ent. faecium SB 18; № 5 (70:30 %) – (Premium + Creamy) + Ent. faecium SB 18; № 6 (80:20 %) – (Premium + Creamy) + Ent. faecium SB 18; № 7 (90:10 %) – (Premium + Creamy) + Ent. faecium SB 18. The fastest fermentation took place in sample № 1 (pH 4.78 units – 4 h), the slowest in sample №2 (pH 4.81 units – 6 h), where only pure culture of E. faecium SB 18 was used. The fermentation time in sample №3 was initially slower and then more active (pH 4.77 units – 4 h). The acidity increased more moderately in samples № 4, 5, 6, 7 for 4 h, and at the end of fermentation was 4.84 units, 4.76 units, 4.81 units. and 4.75 units. in accordance. According to organoleptic evaluation, the experimental samples were characterized by slight differences. In general, it is noted that the addition of microbial culture of E. faecium SB 18 improves the taste of yogurt. Samples № 6 and № 7 with the addition of E. faecium SB 18 strain in the amount of 20 and 10 % were noted for the best organoleptic properties. According to the score scale, the above-mentioned samples received the highest number of points – 48, out of a possible 50. The dependence of the acidity of yogurt during storage was established on the dose and composition of the bacterial preparation. It was investigated that the acidity of yogurt, which contained an additional strain of E. faecium SB 18 in the ratios of 100:100 (sample 3) and 50:50 (sample 4), tends to increase rapidly in acidity, which is associated with increased lactic acid bacteria. It was found that partial replacement of the amount of traditional yogurt leaven in the ratio of 70:30 (sample 5), 80:20 (sample 6) and 90:10 (sample 7) provides the optimal course of the enzymatic process during fermentation and storage. It was found that the use of traditional yogurt leaven YoFlex Premium 1.0 and Creamy 1.0. together with strain E. faecium SB 18 in a ratio of 80:20, provides excellent consumer properties of the product.

Antimicrobial effects of lactic acid bacteria with probiotic ability isolated from traditional yogurts on foodborne pathogenic microorganisms

Antimicrobial effects of lactic acid bacteria with probiotic ability isolated from traditional yogurts on foodborne pathogenic microorganisms

Potential Human Health Risks Assessment through Determination of Heavy Metal Contents in Regularly Consumed Yogurts in Bangladesh

This study estimated the concentrations of heavy metals in regularly consumed sour, sweet and homemade traditional yogurts in Bangladesh. A total of 300 yogurt samples (sour, sweet and homemade traditional); 100 yogurt samples of each category were considered for this assay. To assess the health risks, the daily yogurt consumption rate and the value of target carcinogenic and non-carcinogenic risks of these yogurt samples were also determined. In sour yogurt samples, detected heavy metal contents were 0.398±0.121 mg/kg, 0.774±0.372 mg/kg, 0.087±0.021 mg/kg, 0.131±0.026 mg/kg, 0.011±0.006 mg/kg, 0.031±0.005 mg/kg, 0.445±0.267 mg/kg and 0.029±0.024 mg/kg while in sweet yogurt samples, detected heavy metal contents were 0.410±0.146 mg/kg, 0.704±0.324 mg/kg, 0.082±0.028 mg/kg, 0.146±0.025 mg/kg, 0.010±0.005 mg/kg, 0.030±0.007 mg/kg, 0.460±0.265 mg/kg, and 0.035±0.026 mg/kg and in homemade traditional yogurt samples, detected heavy metal contents were 0.410±0.147 mg/kg, 1.502±0.367 mg/kg, 0.085±0.020 mg/kg, 0.120±0.024 mg/kg, 0.011±0.005 mg/kg, 0.020±0.005 mg/kg, 0.251±0.174 mg/kg and 0.025±0.021 mg/Kg for Iron (Fe), Copper (Cu), Manganese (Mn), Zinc (Zn), Lead (Pb), Cadmium (Cd), Chromium (Cr) and Arsenic (As) respectively. Among the analyzed heavy metals, highest concentration of Cu and lowest concentration of Pb was detected in all yogurt types. The values of estimated daily intake (EDI), Target hazard quotient (THQ), Total THQ (TTHQ) and Target Carcinogenic risk (TCR) confirmed that, there have no chances of any kind of carcinogenic and non-carcinogenic risks from these yogurt samples.

Micronutrient Content and Total Lactic Acid Bacteria of Dadiah Pudding as Food Supplementation for Pregnant Women

BACKGROUND: Dadiah, traditional yogurt from Indonesia, which is known as a source of probiotics, also contains micronutrients. AIM: This descriptive study aimed to determine whether additional ingredients and processes during the manufacture of Dadiah pudding maintain the iron, zinc, calcium, and total lactic acid bacteria (LAB) contents. METHODS: Dadiah pudding was made using Dadiah originated from Bukittinggi, West Sumatra. Micronutrient levels were analyzed according to Indonesian National Standard 01-2896-1998. The total LAB were counted by inoculating samples on Man, Rogosa, and Sharpe agar with serial dilution, and morphological identification was carried out using gram stain. RESULTS: In 100 g of original Dadiah, mango and chocolate Dadiah pudding contained 347.98, 276.61, and 279.29 mg of calcium; 4.87, 3.75, and 6.31 mg of zinc; 6.53, 6.60, and 9.39 mg of iron; and 6.4 × 10⁹, 6.1 × 10⁹, and 2.4 × 10⁹ CFU/ml LAB, respectively. CONCLUSION: This study found that modifying the original Dadiah into Dadiah pudding has been proved to affect the concentration of calcium, zinc, and iron and to maintain total LAB. We suggest that consuming Dadiah pudding may be a good choice as a food supplementation for pregnant women to optimize the golden period outcomes.

MOLECULAR CHARACTERIZATION OF ISOLATED LACTIC ACID BACTERIA FROM DIFFERENT TRADITIONAL DAIRY PRODUCTS OF TRIBES IN THE FARS PROVINCE, IRAN

Various traditional dairy products could be considered as an abundant source for Isolation/collection of new lactic acid bacteria (LAB) with unique characteristics. The present researchaimed to investigate the morphological, biochemical and genotypic characterization of dominant lactic acid bacteria that were isolated from traditional dairy products in Iranian tribes . A total of 75 samples of traditional yogurt, doogh from dairy units in Fars province were randomly collected. Isolation of lactic acid bacteria, biochemical and genotypic identification were conducted. Totally, 157 LAB isolates were selected. Cocci and rod shape LAB were 53.50% and 46.49%, respectively. Biochemical tests showed the occurrence of 40.6% of the strains were Streptococcus, 2.25% of the strains were enterococci and 20.3% of the strains were lactococci. Most isolated lactobacilli were related to Lactobacillus plantarum and Lactobacillus bulgaricus. Genetically the presence of the following species was verified: Lactococcus lactis subsp. cremoris, Lactobacillus plantarum, Streptococcus thermophilus, Lactobacillus fermentum, Lactococcus lactis subsp. lactis, Lactobacillus bulgaricus, Lactobacillus helveticus, and Lactobacillus casei. The current study showed that thestrains which were isolated from traditional dairy products were not only appropriatefor use as starter adjuncts or cultures, but also they may provide a valuable gene pool for research and production of commercial starters with specific traits.

PROXIMATE AND SHELF LIFE EVALUATION OF SOYMILK YOGHURT WITH ADDED SACCHAROMYCES BOULARDII

The effect of adding Saccharomyces boullardii in soya yoghurt was studied. The control was made with soya milk and traditional starter culture (Lactobacillus bulgaricus and Streptococcus thermophilus) while the other three treatments were made by adding 1%, 2%, 3% of S. boulardii with traditional yoghurt starter. Proximate composition of all yoghurt treatments were determined after fermentation time. Shelf-life evaluation of yoghurt treatment were observed during the storage time. During the proximate composition evaluation, treatment with 3% S. boulardii had highest moisture and protein content at 83.43±0.03 and 92±0.3 but least ash and carbohydrate content at 1.2±0.18 and 4.27±0.3. During shelf-life evaluation, titratable acidity and syneresis values of yoghurt with S. boulardii were slightly increased while pH and water holding capacity decreased compared with control yoghurt. After 21 days, S. boulardii counts were 5.89, 6.07 and 6.03 log.cfu/ml for yoghurt with 2% and 3% S. boulardii respectively whereas L. bulgaricus and S. thermophilius of yoghurt with 3% S. boulardii were 7.45 and 8.38 log.cfu/ml respectively. The addition of S. boulardii improved the survivability of the bacteria starter culture.

Isolation and identification of lactobacilli from traditional yogurts as potential starter cultures

Potential lactobacilli isolates (20) from traditional yogurt samples were primarily selected based on their antimicrobial activity against common pathogens of Escherichia coli and Staphylococcus aureus. Following this, the highest acidity values were determined in K1 (0.63%) and EPSC2 (0.61%) isolates after 6 h; KKC1 (1.62%) and EPSC2 (1.59%) after 24 h. The highest proteolytic activity in the first 36 h of incubation was observed in K11B, M2, CBB5 and CBB3 isolates while the lowest activity was in K10, M6, and KKC2 isolates, respectively. Subsequently, 10 isolates that carry the potential to be used as yogurt starter cultures were picked and identified at the molecular level using 16S rDNA sequences and a phylogenetic tree was created. The closest species to all of the selected isolates was determined to be Lactobacillus bulgaricus. The flavor profiles of these isolates indicated that the highest acetaldehyde concentrations were detected in the KKC1, M6, and KKC2 isolates while these values were found to be higher than that of the commercial Lactobacillus. Consequently, CBX, CBH4, M6, EPSC2, and KKC2 were found to possess the potential to be used as starter cultures therefore they could be recommended for utilization in fermented dairy products, especially yogurt.

Temporal dynamics of probiotic Lacticaseibacillus casei and rhamnosus abundance in a fermented dairy product evaluated using a combination of cultivation-dependent and -independent methods

Benchmark of cost-efficient and accurate methods for quantifying probiotics in dairy products represents great interest to the food industry. The advantages of cultivation-independent techniques over the traditionally used cultivation-based ones are to be investigated in this context.We evaluated the levels of Lacticaseibacillus casei and rhamnosus in multiple formulations of a fermented dairy product fortified with these probiotics during the shelf-life using cultivation, taxon-specific qPCR augmented with propidium monoazide (PMA) viability test and 16S rRNA gene sequencing. The analyzed products were the yogurts produced with traditional yogurts starter cultures including Bifidobacteria or without them. The effect of the starter culture on probiotics viability and abundance was assessed. The methods for probiotic profiling were compared.All methods confirmed high levels for the probiotics throughout the shelf-life. The PMA-qPCR showed that their non-viable proportion was low. The formulations with the starter cultures including Streptococcus and Lactobacillus were associated with a lower abundance of each probiotic compared to those that additionally had Bifidobacterium in the starter culture. The total microbial composition according to the sequencing was generally as expected, but the method was of limited use for profiling the probiotic levels due to the data compositionality and dominance of the starter culture taxa.