Manufacture Of Yogurt Research Articles

CHARACTERISTICS OF JUWET FRUIT YOGHURT WITH THE ADDITION OF SKIM MILK AND LACTIC ACID BACTERIA STARTER

In this study, the manufacture of juwet fruit yoghurt was studied with different treatments of adding skim milk and lactic acid bacteria starter. Yogurt is a processed milk product made through bacterial fermentation. Yogurt is known as a good source of protein, calcium, and probiotics, which can support digestive health and the immune system. Juwet fruit has a high antioxidant and vitamin C content so that juwet fruit has interesting potential to be made into yoghurt. Skim milk is used to utilize high lactose and protein so that the growth of lactic acid bacteria can grow optimally. Lactic acid bacteria are used for preservation, providing texture, and adding flavor to yoghurt drinks. The purpose of this study was to determine the addition of skim milk and lactic acid bacteria starter on the physicochemical, microbiological, and organoleptic characteristics of juwet yoghurt. This study used a Completely Randomized Design (CRD) factorial pattern consisting of two factors. Factor 1 addition of skim milk (5%, 7%, 9%). Factor 2 addition of starter (5%, 7%, 9%). Each treatment was repeated three times. The data obtained were analyzed using analysis of variance (ANOVA). If there is a significant difference between treatments, it is continued with the Duncan test (DMRT) and organoleptic test using the Scoring test with 25 trained panelists. The treatment of adding 9% skim milk and 9% starter was the best treatment that produced juwet yoghurt with a protein content of 2.1% ± 0.036, total titratable acid 2.1% ± 0.1, total soluble solids 22.7ºBrix ± 1.53, total lactic acid bacteria 10.5 log CFU/ml ± 0.023, pH 3.7 ± 0.058, antioxidants 34.0% ± 0.117, viscosity 6.8% ± 0.058, Vitamin C 5.8 ± 0.3, and organoleptic tests of color 2.88 (rather like), taste 3.24 (rather like), aroma 2.68 (rather like), texture 3.76 (like).

Validation of an Optical Technology for the Determination of pH in Milk during Yogurt Manufacture.

Current systems that allow inline pH control in the fermented dairy industry have drawbacks, such as protein adhesion on the non-glass pH probes, measurement distortion, frequent recalibration needs, and sensitivity to extreme pH conditions encountered during clean-in-place operations. Therefore, the objective of this study was to validate the feasibility of estimating the pH of milk during the yogurt making process by using a NIR light backscatter sensor measuring under different fermentation temperatures and milk protein concentrations using a mathematical model that correlates the light scatter signal with pH. Three replications of the experiment with two protein concentrations (3.5 and 4.0%) and two fermentation temperatures (43 and 46 °C) were used to validate this inline pH prediction model. Continuous and discontinuous measurements of pH were collected as a reference during fermentation, simultaneously with the light backscatter data acquisition. Also, the effect of adjusting the initial voltage gain of the light scatter device on the accuracy of the pH prediction model was evaluated. Temperature and initial voltage were the main factors affecting the fitting accuracy of the model. The adjustment of the initial voltage gain improved the pH prediction model fit. The model has been successfully validated for both continuous and discontinuous measurements of pH, with SEP values < 0.09 pH units and CV < 1.78%. The proposed optical inline and non-destructive method was feasible for inline pH monitoring of milk fermentation, avoiding traditional manual pH measurement.

Molecular Characterization and Genetic Improvement of Some Bifidobacterium Isolates for Yogurt Manufacture use

Molecular Characterization and Genetic Improvement of Some Bifidobacterium Isolates for Yogurt Manufacture use

Study of the Physical, Chemical, and Biologically Active Properties of Avocado Pulp (Persea americana), and Its Use in the Preparation of Some Functional Dairy Products

This research conducted with the aim of manufacturing healthy products (yoghurt and local cream cheese) rich in bioactive compounds and healthy fatty acid using avocado fruit pulp. Avocado pulp used in the manufacture of yoghurt at two, four, and six percent, and the yoghurt stored at 4ﹾ C for seven days. Local cream cheese was handmade by replacing animal butter with 15% avocado pulp. The content of phenolic compounds in fresh avocado pulp determined using HPLC, where it was found to be rich in kaempferol 30.88 ppm, ferulic acid 30.25 ppm, apigenin 22.58 ppm, quercetin 18.98 ppm, and P-coumaric acid 12.66 ppm, as well as rich in some fatty acids: oleic 59.58%, palmitic 17.58%, and α-linolenic 18.05%. Compared to the control sample at the first day of storage, the avocado-fortified yoghurt led to an increase in antioxidant activity by 10.86%, 25.12%, and 34.63%, and in total phenolic content by 129.55%, 343.18%, and 404.55%. The yoghurt sample at four percent was the most accepted in texture, taste, flavor, and general acceptance, and the avocado added a buttery, astringent, and distinct taste to the avocado-fortified samples. Also, the manufactured of local cream cheese by avocado led to a decrease in moisture and fat, and an increase in acidity and total solids, and it was possible to obtain a low-fat functional food with high nutritional value. Results showed that supporting yoghurt with avocado had a positive effect on reducing the total number of microorganisms and was free of molds, yeasts, and coliform growths during storage.

The study of relationship between taste and wheat bran protein isolate fortification during high-protein yogurt manufacturing

High-protein (HP) food is becoming a popular and nutritionally valuable commodity. The most common protein fortifiers are milk whey or soy protein isolates. However, one of the potentially promising sources of quality protein isolate is wheat bran, the secondary product of wheat milling. Wheat bran protein isolate (WBPI) can be obtained using a sustainable and environmentally friendly pH shift method. Considering its nutritional properties, incorporating WBPI into people's diet is convenient. This work focuses on protein fortification of plain yogurt using WBPI while maintaining sensory acceptability. Direct fortification of yogurts with WBPI to achieve 5 % and 10 % protein content revealed two main sensory defects – bitterness and sandiness. Several approaches, such as grinding WBPI, protein blending, and WBPI encapsulation, were applied to improve the overall impression score of HP yogurts. It was found that eliminating the sandiness of WBPI-fortified yogurt is not possible by reducing WBPI particle size. Blending WBPI with dried milk decreased bitterness, but the products lacked amino acid diversity. The most effective procedure to mask the sensory defects was WBPI encapsulation using alginate, revealing an appropriate way to incorporate natural plant proteins into HP food.

Development of technology for the manufacture of yogurt from combined cow and mare's milk enriched with plant extract in Kazakhstan

In recent decades, more and more consumers are paying attention to a healthy diet and foods enriched with nutrients. In response to this demand, new production technologies are being actively developed in the food market. One of the interesting innovations in this area is the development of a technology for making yogurt from combined cow and mare milk enriched with plant extract in Kazakhstan. The purpose of this work is to determine the optimal technology for the manufacture of yogurt from combined milk, with the integration of advanced methods for processing the finished product and raw materials and to consider ways to obtain industrial strains of lactic acid bacteria that can potentially be used in the manufacture of such a product. To determine the list of bacteria, the data prescribed in the state standards and the results obtained in the publications of the reviewed studies were used. Also, the work uses theoretical methods of scientific knowledge, such as deduction, induction, abstraction, analysis and comparison of methodologies described in the scientific literature and synthesis based on their theoretical methodology for further testing. The state regulatory documents regulating various aspects of the manufacture of fermented milk products have been studied. The probable optimal sequence of processes for the manufacture of a fermented milk product has also been determined, starting from the preliminary preparation of raw materials of animal origin, to their combination and fermentation itself. At the same time, the number of manipulations carried out due to exposure to high temperatures is minimized. The main directions for checking the compliance of the finished product with state standards defined for similar products and how such a product will meet consumer expectations are outlined. The results of this work will form the theoretical basis for experimental studies to be carried out in the future.

Bifidobacterium species viability in dairy-based probiotic foods: challenges and innovative approaches for accurate viability determination and monitoring of probiotic functionality.

Bifidobacterium species are essential members of a healthy human gut microbiota. Their presence in the gut is associated with numerous health outcomes such as protection against gastrointestinal tract infections, inflammation, and metabolic diseases. Regular intake of Bifidobacterium in foods is a sustainable way of maintaining the health benefits associated with its use as a probiotic. Owing to their global acceptance, fermented dairy products (particularly yogurt) are considered the ideal probiotic carrier foods. As envisioned in the definition of probiotics as "live organisms," the therapeutic functionalities of Bifidobacterium spp. depend on maintaining their viability in the foods up to the point of consumption. However, sustaining Bifidobacterium spp. viability during the manufacture and shelf-life of fermented dairy products remains challenging. Hence, this paper discusses the significance of viability as a prerequisite for Bifidobacterium spp. probiotic functionality. The paper focuses on the stress factors that influence Bifidobacterium spp. viability during the manufacture and shelf life of yogurt as an archetypical fermented dairy product that is widely accepted as a delivery vehicle for probiotics. It further expounds the Bifidobacterium spp. physiological and genetic stress response mechanisms as well as the methods for viability retention in yogurt, such as microencapsulation, use of oxygen scavenging lactic acid bacterial strains, and stress-protective agents. The report also explores the topic of viability determination as a critical factor in probiotic quality assurance, wherein, the limitations of culture-based enumeration methods, the challenges of species and strain resolution in the presence of lactic acid bacterial starter and probiotic species are discussed. Finally, new developments and potential applications of next-generation viability determination methods such as flow cytometry, propidium monoazide-quantitative polymerase chain reaction (PMA-qPCR), next-generation sequencing, and single-cell Raman spectroscopy (SCRS) methods are examined.

Formulation and evaluation of a probiotic drink fortified chlorella for enhanced health benefits

Probiotics are microorganisms that have benefits when consumed, they can be found in yogurt. Yogurt commercially lack protein; the addition of chlorella is a solution due to chlorella contains high protein. The research aimed to determine the effect of chlorella fortification on the quality characteristics of yogurt and the best concentration of chlorella addition in the manufacturing of yogurt. The experimental method using a non-factorial Completely Randomized Design (CRD) consisting of 4 treatment levels: without the addition of chlorella (PC0), 0.75% of chlorella (PC1), 1% of chlorella (PC2), and 1.25% of chlorella (PC3). The parameters tested in this research were hedonic testing and quality, chemical composition, physical properties, and microbiological assay. The results showed that yogurt fortified with 1% chlorella was most favorable by consumer acceptance, with organoleptic characteristics: green and thick color, slightly characteristic aroma of chlorella, and slightly sour taste typical of chlorella. Meanwhile, the proximate composition of this yogurt contains 81.26% moisture, 3.77% protein, 2.30% fat, 0.89% ash, 1.47% fiber; physical properties of pH 4.65, Aw 0.75, viscosity 205.85 cP; and microbiological value of acid total 1.95%, and lactic acid bacteria 2.1×107 cfu/g. Therefore, the yogurt chlorella is suitable for consumption and can enhance health benefits.

Development of millet-acid whey formulations with nutritional, microbiological, and sensory characterization

IntroductionDisposal of the acid whey waste stream is one of the major challenges faced by the Greek yogurt industry. However, based on its physicochemical characteristics and composition analysis, it has huge potential in the health industry. Likewise, millets are highly nutritive and health benefitting ancient grains. Combining acid whey and millet matrix can help in solving the problem of both food losses and food security. Hence, the objective of the study is to analyze the enhancement or degradation of the nutrition profile when acid whey is combined with millet matrix using spray-drying technology.MethodThe methodology of the study includes composition analysis and functional characterization based on antioxidant properties, microbial analysis, and sensory evaluation.Results and discussionThe results showed that there was enhancement of functional properties of the millet-acid whey formulation matrix specifically in terms of polyphenolic compounds, lactose content, and mineral content. Overall, the study aims to provide an alternative method for the utilization and consumption of acid whey that is currently being mishandled and considered as waste by the Greek yogurt manufacturing companies.

An Innovative Method for the Production of Yoghurt Fortified with Walnut Oil Nanocapsules and Characteristics of Functional Properties in Relation to Conventional Yoghurts.

Polyunsaturated fatty acids (PUFAs) are crucial nutrients involved in a plethora of metabolic and physiological processes. PUFAs have been extensively researched for their effects on human nutrition and health. The high demand for these fatty acids offers the possibility of adding vegetable oils to dairy products such as yoghurt. The aim of this study was to produce nano/microcapsules comprising walnut oil through exclusively natural ingredients utilised in yoghurt manufacturing. Additionally, the study tested yoghurt supplemented with PUFAs using the acquired nano/microcapsules. Chemical and physiochemical properties, microbiological analysis, rheological measurements, texture analysis, scanning electron microscope (SEM) analysis, ATR-FTIR spectroscopy, and sensory and fatty acids profile analysis were performed. A physico-chemical analysis highlighted the impact of oil addition on fat and dry matter concentration, revealing an increased quantity of said components in yoghurt after oil addition. Based on the identified parameters for potential and active acidity in the yoghurts, normal lactic fermentation was observed. Furthermore, the addition of oil was found to have an impact on the pH of the yoghurt. Microbiological analysis indicated that the incorporation of nano-encapsulated walnut oil did not have any notable effect on the abundance of determined microorganisms in the yoghurt. However, it was observed that the number of Lactobacillus delbrueckii ssp. bulgaricus increased as a result of storage. The incorporation of enclosed oil in yoghurt resulted in negligible alterations in rheological and sensory characteristics when compared with the plain variant. The addition of oil had an effect on most of the analysed fatty acids. Fortified yoghurt shows a more favourable proportion of the fatty acid groups tested (SFA, MUFA, and PUFA) and lower values of fat quality factors (AI and TI).

Manufacture and characterization of a novel dairy-free quinoa yogurt fermented by modified commercial starter with Weissella confusa.

Non-dairy yogurt is increasingly thought to be healthy food. However, no suitable starters limit its development. This study aimed to develop a novel and functional quinoa yogurt with a modified commercial starter. Compared with the other lactic acid bacteria (LAB), Weissella confusa showed a better fermentation performance of quinoa utilization. The synergistic effect of W. confusa and the commercial starter promoted the growth of LAB. It increased the fermentation rate of quinoa yogurt, further improving its texture, rheological properties, and storage stability. The modified starter significantly increased the nutritional qualities of the quinoa yogurt, including polyphenol content, antioxidant activity, digestive enzyme inhibition, and reduced postprandial blood glucose ability. Additionally, the modified starter enhanced the digestibility and bioaccessibility of polyphenols, protein, and fat in fermented quinoa yogurt. Overall, the commercial starter with W. confusa showed great potential for possible application in quinoa yogurt development.

Effect of Wild Strawberry Tree and Hawthorn Extracts Fortification on Functional, Physicochemical, Microbiological, and Sensory Properties of Yogurt.

The composition analyses and health-promoting properties (antioxidant capacity, antidiabetic, and antihypertensive properties) of wild fruit extracts and the effect of the incorporation of strawberry tree (STE) and hawthorn (HTE) extracts on the physicochemical, instrumental textural, microbiological, and sensory parameters of yogurts were evaluated. The incorporation of wild fruit extracts in yogurt increased antioxidant and antidiabetic properties (inhibition of digestive α-amylase, α-glucosidase, and lipase enzymatic activities) compared to the control, without decreasing their sensory quality or acceptance by consumers. The hawthorn yogurt (YHTE) showed the highest total phenolic content (TPC) and antioxidant capacity (ABTS and ORAC methods). Yogurts containing wild fruit extracts and dietary fiber achieved high overall acceptance scores (6.16-7.04) and showed stable physicochemical, textural, and microbiological properties. Therefore, the use of wild fruit extracts and inulin-type fructans as ingredients in yogurt manufacture stands as a first step towards the development of non-added sugar dairy foods for sustainable health.

Application of plant-based proteins for fortification of oat yogurt storage stability and bioactivity.

The purpose of this study was to evaluate the addition of plant-based peanut protein isolate (PNP) and commercial pea protein (CPP) on the quality of oat yogurt (OY). PNP and CPP were partially characterized for techno-functional properties. PNP had higher solubility (acidic and basic regions) and emulsifying activity than CPP. The water absorption capacity of CPP is significantly (p<0.05) higher than PNP. Amino acid profiles of PNP and CPP were promising for the nutritional enhancement of OYs. OYs with PNP or CPP (0.5, 1, 2% w/v) were stored for 21 days and compared to the control group with no protein. On the 21st day of storage, (i) PNP- or CPP-added OYs were found to be comparable to the control with respect to post-acidification and viscosity, (ii) syneresis was more evident in PNP-added OYs than in CPP-added ones, (iii) total color change of 1% CPP-added OY was equal to the control, and (iv) hardnesses of control, 2% PNP, and 2% CPP-added OYs were 0.29±0.00, 0.39±0.01, and 0.45±0.00N, respectively. No adverse sensory effects were detected for CPP or PNP addition. Both proteins increased the total phenolic, soluble protein, antioxidant, antihypertensive, and α-glucosidase inhibition activity of oat milk and OYs, with PNP superior to CPP overall. Compared to oat milk, the fermentation process increased ACE inhibition activity in in vitro digested samples, whereas it reduced digested yogurts' antioxidant activity. Utilization of PNP in OY can solve the waste problem of peanut producers and the texture problem of the OY producers while formulating a functional product. PRACTICAL APPLICATION: Plant-based (PB) yogurts have a growing consumer demand. The low-protein content of PB yogurts results in low acceptance with respect to their undesirable textural and sensorial attributes. This study provided a technical basis for the PB yogurt manufacturers focusing on the addition of commercial pea protein and isolated peanut protein into oat yogurt formulation without any thickeners or flavors. In vitro digestion of protein-added oat milk and oat yogurts showed the benefits of fermentation on bioactivity to the consumers.

Extraction of protein from apricot kernel oil press cake (AKOPC) through innovative techniques and the formulation ofsupplemented yogurt.

The apricot kernel oil press cake (AKOPC) is a high protein natural by-product of oil mechanical expression with potential uses in cosmetics, medicines, and food. The purpose of this research was to improve the protein extraction process from apricot kernel oil press cake by using enzymatic extraction (EEP), aqueous extraction (AEP), and ultrasound extraction (UEP) process. Protein extraction by AEP was facilitated by a low solid-liquid ratio (SLR) (1:15.97) and prolonged reaction durations (3.30 h), resulting in extraction yields of 68%. When compared to the AEP by similar reaction time, increased enzyme utilization (0.90%) in the EEP resulted in greater protein extraction yields (70%) in a shorter reaction time. In addition to AEP and EEP, ultrasound extraction was also used to improve protein extractability. Temperature (50°C), power density (225 W/L), and extraction duration (20 min) were shown to be the best extraction points. Protein yield was found to be 56.47% at ideal UEP conditions. The experimental values for these reactions were found to be equivalent to the predicted values formed by the mathematical models. When supplementary skimmed milk powder (SMP) was substituted with apricot kernel protein (AKP) in the yogurt manufacturing process, the total solids, average titratable acidity, total protein, and fat contents of the yogurt were increased. In contrast, pH and syneresis values decreased as AKP increased in the resulting yogurt, whether fresh or after 7 days of cold storage. Substitution of additional SMP with AKP in yogurt production might be recommended up to 35%.

The effect of using pomegranate and strawberry juices with red beet puree on the physicochemical, microbial and sensory properties of yoghurt

There is currently a growing interest in creating dairy products fortified with natural fruits containing (phenolic and antioxidant compounds) and safe for human consumption. Therefore, this trend was applied in the current study, where a mixture of red beet puree with pomegranate and strawberry juices were used in the manufacture of yoghurt. The effect of supplementing yoghurt with the previous mixture on the physicochemical, microbiological properties, color, antioxidant activity, total phenolic content, reduced sugars, was studied. The use of fruit juices had slightly significant effect on the acidification rate of milk and the basic physical and chemical properties of the resultant yoghurt, but it increased slightly the red color. The total phenol content and the antioxidant activity were increased in yoghurt containing the mixture of fruit than in control one. Microbiological results revealed that the counts of lactic acid bacteria were increased in all treatments during storage and reached the maximum after 7 days of storage as slightly lower counts were recorded in the control treatment than in the other treatments, when fresh and during the storage period. All treatments were free from coliform and yeast and molds when fresh but it were noticed in all treatments at the 7 day. Organoleptic examination indicates that fruit treatments yoghurt gained the higher significant (p ≤ 0.05) scores as compared to control, when fresh and during storage period. Generally, results of this study show that the use of the mixture of the former fruits may be applied to produce a functional yoghurt rich in phenolic components, antioxidants activity and nutrients.

Sonication as a pre-processing step to alter acid whey generation during Greek yoghurt manufacture.

We investigated sonication as a pre-processing step to reduce acid whey generation during Greek yoghurt manufacture. The generation of a large amount of acid whey during the production of Greek yoghurt is an ongoing problem in the dairy industry and many studies are currently focusing on reducing it. We focused on the use of ultrasonication as a novel approach to minimize the casein fraction in the acid whey stream and simultaneously improve the gel properties. Ultrasound applied before the fermentation modified the structural properties and bonding behaviours of milk proteins, and enhanced the retention of casein in the yoghurt gel after the fermentation and straining steps. Therefore, the use of low-frequency ultrasonication as a pre-processing step may have the potential to provide significant economic benefits to the Greek yoghurt manufacturing process. Moreover, it improved the nutritional and physicochemical properties compared to regular Greek yoghurts.

Aerobic Cultivation of Mucor Species Enables the Deacidification of Yogurt Acid Whey and the Production of Fungal Oil.

As the Greek-style yogurt market continues to experience prosperous growth, finding the most appropriate destination for yogurt acid whey (YAW) is still a challenge for Greek yogurt manufacturers. This study provides a direct alternative treatment of YAW by leveraging the abilities of Mucor circinelloides and Mucor genevensis to raise the pH of YAW and to produce fungal biomass with a high lipid content. Aerobic cultivations of these species were conducted in YAW, both with and without the addition of lactase, at 30 °C, and 200 rpm agitation. The density, pH, biochemical oxygen demand (BOD), biomass production, lipid content, fatty acid profile, and sugar and lactic acid concentrations were regularly measured throughout the 14-day cultivations. The data showed that M. genevensis was superior at deacidifying YAW to a pH above 6.0-the legal limit for disposing of cultured dairy waste. On the other hand, M. circinelloides generated more fungal biomass, containing up to 30% w/w of lipid with high proportions of oleic acid and γ-linolenic acid. Additionally, the treatments with lactase addition showed a significant decrease in the BOD. In conclusion, our results present a viable treatment to increase the pH of YAW and decrease its BOD, meanwhile generating fungal oils that can be further transformed into biodiesel or processed into functional foods or dietary supplements.

A natural whitening alternative from upcycled food waste (acid whey) and underutilized grains (millet)

The dairy industry faces a daunting challenge in managing acid whey (AW), a byproduct of Greek yogurt manufacturing that is costly to dispose of and challenging to incorporate into other food products. However, recent studies have demonstrated that AW can be transformed into a viable white powder by encapsulating it in millet flour. Recently, concerns over the safety of the commonly used food-grade whitener titanium dioxide (TiO2) have arisen, and the search for an alternative food-whitening agent has become essential. This study evaluated the color attribute, proximate composition, sugar profile, amino acid profile, total phenolic content, antioxidant activity, and antinutrient content of the novel acid whey millet (AWM) powder. The L* values of the AWM powders were significantly higher than TiO2 and the rest of the millet formulations. The crude protein content in the AWM powders was significantly (p < 0.05) lower when compared to the crude protein content in millet flours. AWM powders had higher lactose levels and retained all major amino acids after spray drying. Macrominerals (P, K, Ca, and Na) and microminerals (Zn and Cu) significantly increased in the AWM powder, while tannin content was reduced in AWM powders. These findings suggest that AWM powder is a white powder that contains a wide range of components with high nutritional value that could be readily incorporated into various applications. In summary, this study provides a valuable contribution to the dairy industry by highlighting the potential of AWM powders as a natural alternative food whitening agent to TiO2.

Screening of Lactic Acid Bacteria Strains to Improve the Properties of Non-fat Set Yogurt by in situ EPS Production

Some lactic acid bacteria (LAB) are capable of producing exopolysaccharides (EPS), which can be used in the dairy industry to reduce syneresis and improve the viscosity and texture of fermented products. The aim of the present study was to screen the EPS-producing capacity of 123 LAB strains isolated from fermented foods to search for those able to produce EPS with the optimal technological aptitude to be applied in non-fat set yogurt manufacture. They were grown on MRS-sucrose and assigned to ropy or mucoid phenotype depending on the appearance of the colonies. Twenty-five of them were selected and assayed for production of both cell-bound EPS (EPS-b) and EPS released to the medium (EPS-r). Those resulting in the most EPS producers (Levilactobacillus brevis UCLM-Lb47, Leuconostoc mesenteroides subsp. mesenteroides 6F6-12 and Leuconostoc mesenteroides subsp. mesenteroides 2F6-9) were used to manufacture non-fat set yogurts. These yogurts were analyzed for microbiological and physicochemical properties (pH, titratable acidity, total solids), water-holding capacity, apparent viscosity, and sensory characteristics during a 28-day cold storage period. The yogurts made with the selected strains showed higher values of water-holding capacity, EPS concentration, and viscosity in the mouth than the control yogurt, which presented a more fluid texture. The results obtained suggest that the three selected strains could be used to replace hydrocolloids in non-fat set yogurt formulation, obtaining a clean-label product that would improve consumer acceptance.Graphical

Effects of the Incorporation of Hydrogen and Nitrogen into Milk on the Reducing and Acidification Capacities of Yoghurt Bacteria

The use of gases in different food applications has increased in the last decades. The incorporation of hydrogen into yogurt was reported to improve the organoleptic properties of some dairy products. A study is needed to understand the effect of this application on the behavior of yogurt bacteria during the fermentation stage. The effects of H2- and N2-incorporation into milk on the acidification and reducing capacities of Lactobacillus delbrueckii subsp. bulgaricus (LB) and Streptococcus thermophilus (ST) were envisaged. A data acquisition multiparameter interface equipped with pH and redox electrodes was used for continuously measuring and recording values. H2 increased the acidification capacity of ST (+10%) and the reducing capacity of LB (+13.7%), whereas N2 increased the acidification capacity of ST (+13.3%) and decreased the reducing capacity of LB (-21.47%) and ST (-18.88%). H2 increased the coagulation time of LB (+12.96%) and ST (+6.15%). Results could reveal the promotive role of hydrogen on the metabolic activity of yogurt bacteria in single cultures and these bacteria grow better in the presence of hydrogen in milk. These results will allow yogurt manufacturers to better understand the behavior of yogurt bacterial strains when the preparation of gas-incorporated yogurt is envisaged and better control its quality attribute notes.