Yogurt, a widely consumed fermented milk product, is known for its health benefits attributed to the presence of probiotic bacteria.This study explores the impact of starter cultures on the texture and microbiological quality of yogurt. The production involved two types of starter cultures: a commercial culture and an heirloom culture. Various parameters, including chemical analysis of raw milk, yogurt production steps, texture parameter analysis, syneresis, water holding capacity, and microbial analysis, were examined. Statistical analysis was performed to indicate the effect of the type of culture on the production of yogurt.Results indicated that the physicochemical analysis of raw cow milk revealed parameters within recommended quality standards. Significant differences in hardness, gumminess, chewiness, resilience, and syneresis between commercial and heirloom yogurts were found. Microbiological analysis demonstrated higher Lactic acid bacteria counts in commercial yogurt compared to heirloom yogurt.  The study provides insights into the influence of starter cultures on textural and microbiological characteristics, emphasizing the importance of standardized production methods for consistent yogurt quality.

This study aimed to evaluate the sensorial, physicochemical, rheological, and microbiological properties of yoghurt fortified with Artemisia absinthium leaf powder during refrigerated storage. The valorization of this plant in food industry was realized by the incorporation of its dried leaf powder at various concentrations in order to produce a new functional yoghurt. It is interesting to note that the fortified yoghurt with the lowest Artemisia dose (2%) was the most preferred by the panel. Furthermore, this fortification did not affect the fermentation parameters nor the viability of lactic starter. During storage, the incorporation of Artemisia powder reduced syneresis and improved the microbiological properties of fortified yoghurts. Besides, at the end of storage, it was noted that yoghurt fortified with 2% of Artemisia powder presented the highest consistency (8.98±0.04 Pa sn) and antioxidant activity (60.08±3.61%) when compared to the control yoghurt. Finally, the accelerated shelf-life test showed the efficiency of Artemisia absinthium powder incorporation by increasing the shelf life of yoghurt by about 4 days.

Among the food products, yogurt is very popular due to its distinctive characteristics such as the presence of lactic acid bacteria and nutritional and therapeutic properties. In any case, consumption of high-fat yogurt can endanger health on the one hand, and on the other hand, reducing fat reduces the quality of the product. Therefore, this research was conducted with the aim of investigating the possibility of improving the characteristics of low-fat stirred yogurt using the treatment of microbial enzyme transglutaminase (MTG) and Persian gum (PG). Low-fat stirred yogurt samples were produced using levels of 0, 0.1 and 0.2% (w/v) of PG gum and levels of 0 and 0.015% (w/v) of MTG enzyme. The physicochemical characteristics and color values of the samples were evaluated during 14 days of storage in the refrigerator. Based on the results of this research, the addition of PG and MTG enzyme significantly reduced acidity and syneresis (p<0.05). Furthermore, the addition of gum increased lightness and redness and reduced yellowness. Although the enzyme treatment like PG increased the lightness and redness, it caused an increase in the yellowness of the yogurt. Storage time significantly decreased syneresis and lightness parameters and increased yogurt acidity and redness and yellowness indexes (p<0.001). In conclusion, the results of this research showed that by using transglutaminase enzyme treatment (0.015%) and adding Persian gum (especially 0.2%), low-fat stirred yogurt with acceptable physicochemical characteristics and color can be produced and the quality of low-fat stirred yogurt can be improved.

The aim of the current research was microencapsulation of Streptococcus thermophilus and Lactobacillus bulgaricus bacteria by coacervation complex method and sodium caseinate and pectin coatings. Sodium caseinate and pectin have electrostatic attraction together at pH=4 and form a complex. Using a scanning electron microscope, the morphology of coacervates was investigated. The properties of pectin and sodium caseinate complexes were investigated by infrared spectrometry tests and measuring the size and distribution of particles. Physicochemical characteristics such as water absorption, pH and acidity and sensory characteristics were also investigated. The results showed that the efficiency of microencapsulation of bacteria by coacervation method was 66.6%. The particle size was 1.565 micrometers and the zeta potential was reported as -16 mV. Electron microscope images showed spherical coacervate without holes and wrinkles on the surface. The results of infrared spectroscopy also showed the creation of electrostatic interactions between pectin and sodium caseinate. Also, microencapsulation of bacteria caused a significant change (p>0.05) in pH (4.6 ± 0.091) and yogurt acidity (1.1 ± 0.03) compared to pH (4.6 ± 0.1). And the acidity of yogurt (0.8±0.01) produced with free bacteria did not. The water content of yogurts produced with microencapsulated bacteria (40±1.1) was reduced compared to yogurts produced with free bacteria (45±0.9) (p<0.05). Bacterial encapsulation has a negative effect on color sensory characteristics. It did not have the smell and taste of the produced yogurts (p>0/05), but a significant difference was observed in the texture of the yogurts produced with microencapsulated bacteria compared to the yogurts produced with free bacteria (p<0/05).

The current research aimed, first, to valorize Tunisian cork oak acorn starch extracted by water soaking method in dairy industry. The effect of its incorporation into milk on the evolution of rheological, sensorial and microbiological properties of stirred yogurt during refrigerated storage was, also, evaluated. No significant effect was observed on fermentation parameters of the acorn starch added product. During 28 days of refrigerated storage, the incorporation of acorn starch did not affect the post-acidification and the viability of the lactic starter cultures. Moreover, the treated stirred yogurt exhibited a lower syneresis value and a higher consistency when compared to the untreated control and that incorporated with industrial modified starch. The findings revealed that acorn starch incorporation extended the shelf life of the final product by about 6 days. Despite its less appreciated color (3.67±0.5), acorn-starch-added yogurt product gained the highest overall acceptability scores (4.11±0.6) by the panel.

Considering the great desire of concumers to consume traditional dairy products and their reluctance to use factory products, this study was conducted with the aim of investigating different chemical and microbial characteristics of traditional youghurt samples offered in Tuyserkan city and compare it with pasteurized yoghurt. The chamical characteristics inclusing percentage of dry matters, moisture content, acidity, pH and fat and microbial characteristisc including total bacterial count, coliforms, mold and yeasts, and Staphylococcus aureus were investigated and compared with the pasteurized sample as a control. The moisture and dry matter content of the samples varied from 87.7-84.33% and from 12.62 to 15.25%, respectively. The fat content of the yogurts produced was between 2.5-2.9 and thus within the range of semi-fat yogurts according to the national standard. No significant difference was observed between different samples in terms of moisture, dry matter and fat (P>0.05). The acidity (percentage by weight in terms of lactic acid) and pH value of various samples ranged from 0.87-1.81 and 3.68-47.4, respectively and were therefore fully in line with the national standard (at least 0.7). Different samples showed a significant difference in terms of pH and acidity (P < 0.05). The results of microbial characteristics indicate the presence of mold and yeast in all samples (100%), coliform in 83.33% and Staphylococcus aureus in 50% of the samples. Regarding microbial characteristics, a significant difference was observed between traditional and industrial samples. Thus, the industrial sample showed the lowest microbial load compared to the traditional yogurt samples (P < 0.05). Therefore, it is strongly recommended to control the incoming raw milk and observe the sanitary conditions during production, packaging and supply in the production of traditional products.

Application of plant extracts in the formulation of sourdough can improve sensory characteristics and shelf-life of the produced bread. In the present study, effects of combined application of fermented sprouted wheat and garlic extract in the formulation of traditional sourdough containing yoghurt and vinegar were investigated on the quality characteristics of loaf wheat bread. Based on the results of texture analysis, among the produced breads the lowest crumb hardness was observed in the sample containing fermented sprouted wheat along with garlic extract (2.94 N), which was significantly (p<0.05) lower than those of the control sample. In addition, combined application of fermentation and sprouting increased the specific volume and reduced the gumminess of the product. Moreover, although the lowest surface growth of Aspergillus flavus was observed on breads containing yoghurt-vinegar and also garlic extract alone, there was no significant difference between the fungal growth rate on the sample containing fermented sprouted wheat along with garlic extract and bread containing calcium propionate. Bread containing fermented sprouted wheat and control sample had no significant difference in terms of overall acceptability. Accordingly, sprouted wheat sourdough containing garlic extract can be used as a biological preservative to improve the quality characteristics and shelf-life of wheat bread.

The rheological behavior of yogurt plays a crucial role in determining the quality of the product. This study aimed to develop a rheological quality control test replicating pseudo-chewing using experimental rheological protocols.

The strawberry stirred yogurt sample was produced, in a 90 g pot, and commercialized in April 2023 by SOUMMAM dairy products, Bejaia, Akbou, Algeria. Rheological properties of a 0.6 ml yogurt sample were evaluated for each test measurement using a rheometer with a cone/plate geometry at a constant temperature of 25±0.1 °C. The shear flow experimental protocol involved three steps: a shear rate ramp, followed by a plateau at the maximum shear rate for 15 min, and afterward the ramp was reversed to measure the downward flow curve. The viscoelastic properties were evaluated by two experimental protocols in the Linear Viscoelastic Region. These properties were studied under oscillatory frequencies (0.1-100 Hz) with and without pre-shearing at 400 1/s for 15 min to simulate the pseudo-chewing process. All experimental data were analyzed and fitted using MS Excel and MS Excel Solver.

The stirred yogurt samples showed a non-Newtonian viscoelastic flow behavior with thixotropy. Both upward and downward shear rate flow curves of the sample exhibited shear-thinning behavior described by the Herschel-Bulkley model with high regression coefficient of R2=0.98 and 0.99, respectively. Dynamic measurements showed that pseudo-chewing causes considerable changes in rheological parameters such as complex modulus, complex viscosity, and loss tangent. The pre-shearing altered complex modulus and complex viscosity, corresponding to an alteration in the yogurt’s firmness and flow properties.

The rheological procedures suggested in the present study can be used as rheological quality control tests of commercial strawberry stirred yogurt. This procedure can successfully simulate pseudo-chewing by offering information on the flow and viscoelastic characteristics of yogurt in the mouth during mastication.

The aim of this study was to examine the effect of Bufferman as a biological regulator on the disappearance of nutrients by bacterial and fungi in anaerobic culture in diets containing different ratios of concentrate to Forage. The experimental diets consisted of different forage to concentrate ratios (respectively 20-80, 30-70, 40-60, 60-40) with treatments included control (zero percent), Bufferman 1% and 2%, and sodium bicarbonate 1 %. This research was conducted in vitro, using a completely randomized design. The experiment results indicated that the disappearance rates of DM , NDF , ADF and rumen pH were influenced by the test diets (P<0.05). Different forage to concentrate ratios (20:80, 30:70, 40:60, 60:40 F:C) were influenced by buffering, resulting in the highest disappearance of DM, disappearance of NDF, and disappearance of ADF in treatments with 1% Bufferman inclusion (P<0.05). According to the present experiment, it can be inclusion of 1% Bufferman led to a significant increase in nutrient disappearance and rumen pH by creating favorable conditions for bacterial and fungal activity throughout the evaluation period.The aim of this study was to examine the effect of Bufferman as a biological regulator on the disappearance of nutrients by bacterial and fungi in anaerobic culture in diets containing different ratios of concentrate to Forage. The experimental diets consisted of different forage to concentrate ratios (respectively 20-80, 30-70, 40-60, 60-40) with treatments included control (zero percent), Bufferman 1% and 2%, and sodium bicarbonate 1 %. This research was conducted in vitro, using a completely randomized design. The experiment results indicated that the disappearance rates of DM , NDF , ADF and rumen pH were influenced by the test diets (P<0.05). Different forage to concentrate ratios (20:80, 30:70, 40:60, 60:40 F:C) were influenced by buffering, resulting in the highest disappearance of DM, disappearance of NDF, and disappearance of ADF in treatments with 1% Bufferman inclusion (P<0.05). According to the present experiment, it can be inclusion of 1% Bufferman led to a significant increase in nutrient disappearance and rumen pH by creating favorable conditions for bacterial and fungal activity throughout the evaluation period.The aim of this study was to examine the effect of Bufferman as a biological regulator on the disappearance of nutrients by bacterial and fungi in anaerobic culture in diets containing different ratios of concentrate to Forage. The experimental diets consisted of different forage to concentrate ratios (respectively 20-80, 30-70, 40-60, 60-40) with treatments included control (zero percent), Bufferman 1% and 2%, and sodium bicarbonate 1 %. This research was conducted in vitro, using a completely randomized design. The experiment results indicated that the disappearance rates of DM , NDF , ADF and rumen pH were influenced by the test diets (P<0.05). Different forage to concentrate ratios (20:80, 30:70, 40:60, 60:40 F:C) were influenced by buffering, resulting in the highest disappearance of DM, disappearance of NDF, and disappearance of ADF in treatments with 1% Bufferman inclusion (P<0.05). According to the present experiment, it can be inclusion of 1% Bufferman led to a significant increase in nutrient disappearance and rumen pH by creating favorable conditions for bacterial and fungal activity throughout the evaluation period.

The aim of this experiment was to investigate the effect of fish waste extract and yogurt juice obtained from the dairy industry on the growth of Baran wheat cultivar. The experiment was conducted in the form of a randomized complete block design with three replications under field conditions. Three methods of fish waste extract (including method 1: potassium hydroxide, method 2: nitric acid + sulfuric acid, and method 3: potassium sulfate + sodium bicarbonate) and also 3 types of zinc, manganese, and iron lactate (prepared from yogurt water) were used in the form of foliar application. The results showed that grain yield and dry weight of wheat straw increased by foliar application of fish extracts and lactates. The grain yield of extraction method 1, method 2 and method 3 was 1.3, 7.2 and 13.9%, respectively. Briefly, it was for method 1 > 3 > 2. Also, the results demonstrated that grain yield and dry weight of straw were in the order of manganese lactate > iron lactate > zinc lactate. The experimental treatments also increased the 1000 grain weight, but this difference was not statistically significant. Foliar spray of lactates and fish extract increased N and K concentrations of grain and straw but had no effect on P concentration. In general, spraying of fish extract and lactates has a positive effect on the growth and yield of Baran wheat cultivar.