Concentrated Yogurt Research Articles

Enhancing Bifidobacterium and lactic acid bacteria activity, and improving oxidative stability in functional algal concentrated yoghurt with Spirulina platensis powder

The purpose of this study was to examine the growing demand for healthy functional dairy products by investigating the incorporation of Spirulina platensis into concentrated yoghurt and evaluating its impact on starter cultures and product properties. A comprehensive analysis demonstrated the potential of spirulina to enhance bifidobacteria growth, acidity, PUFA content, and antioxidant activity in yoghurts, indicating its potential to improve the nutritional quality and oxidative stability of dairy products. The study investigated the impact of different Spirulina ratios on the activity of yoghurt starter cultures, including Lb. casei, Lb. plantarum, Lb. acidophilus, and Bifidobacterium mix. Three concentrated yoghurt samples were prepared, including a control, a probiotic sample, and a sample incorporating Spirulina powder. The findings suggest that while Spirulina did not significantly affect lactic acid bacteria, it noticeably stimulated the growth of Bifidobacterium. Treated samples showed increased acidity and TVFAs, with pH values displaying an inverse trend compared to the control. Clear differences in colour parameters and sensory evaluations distinguished control from treated samples. Additionally, Spirulina supplementation demonstrated a pronounced effect in enhancing antioxidant activity, as observed through DPPH radical scavenging activity, and influencing the peroxide value, reflecting improved oxidative stability in the yoghurt. This successful utilisation of Spirulina suggests its potential application in diverse edible algae in the food sector, especially in dairy products, enhancing both nutritional and sensory aspects, as well as contributing to improved oxidative stability

Occurence of antimicrobial residues in milk and labneh consumed in Lebanon

ABSTRACT Antimicrobials are administered in livestock for different uses leading to milk contamination and several undesirable effects. Because there is a lack of surveillance of antimicrobial residues (AMRs) in milk and dairy products in Lebanon, this study aims to determine the occurrence of AMRs in 90 Lebanese samples of milk and labneh (concentrated yoghurt). Multi-residue screening methods with suitable sample preparations were applied to detect 71 AMRs in milk and labneh, respectively, using LC-MS/MS. Of the total number of samples, 71% was contaminated with AMRs and (fluoro)quinolones and macrolides were the most detected families. Additional confirmation tests proved that 6.7% of the milk samples were non-compliant for the macrolides tilmicosin, tulathromycin and spiramycin. Moreover, some labneh prepared from contaminated milk samples was analysed to determine the fate of AMRs during the manufacturing process. The results showed that some AMRs could be concentrated, eliminated or degraded, based on their physicochemical characteristics.

Incorporation of Powdered Jambolan and Acerola Pulp in Concentrated Yogurt: PhysicoChemical Characteristics, Texture, and Consumer Acceptability

ABSTRACT Yogurt is a source of healthy bacteria and proteins. Consumption of fruits is beneficial for health. In this sense, the objective of this work was to evaluate the physicochemical composition, texture, and sensory acceptance of concentrated yogurts with addition of mixed pulp of jambolan and whole and powdered acerola. Five concentrated yogurts were prepared: F1 – Yogurt Control, F2 – Yogurt with 20% mixed pulp, F3 – Yogurt with 10% freeze-dried pulp, F4 – Yogurt with 10% lyophilized pulp with maltodextrin, and F5 – Yogurt with 10% dehydrated pulp (in oven). Yogurts with the addition of powdered mixed pulps showed a reduction in water activity, water content, and syneresis, in addition to an increase in acidity and ash. The incorporation of mixed pulp into yogurt increased the content of bioactive compounds. The texture profile showed that the F4 yogurt presented the best results. In the sensorial evaluation, the yogurts tested were well accepted by the consumer.

The Effect of Aromatic Plant Extracts Encapsulated in Alginate on the Bioactivity, Textural Characteristics and Shelf Life of Yogurt.

The article investigated the antioxidant and antimicrobial activity of extracts from two aromatic plants-Satureja hortensis L. (SE) and Rosmarinus officinalis L. (RE), encapsulated in alginate, on-yogurt properties. The encapsulation efficiency was controlled by FTIR and SEM analysis. In both extracts, the individual polyphenol content was determined by HPLC-DAD-ESI-MS. The total polyphenol content and the antioxidant activity were spectrophotometrically quantified. The antimicrobial properties of SE and RE against gram-positive bacteria (Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus, Geobacillus stearothermophilus), gram-negative bacteria (Escherichia coli, Acinetobacter baumannii, Salmonella abony) and yeasts (Candida albicans) were analyzed in vitro. The encapsulated extracts were used to prepare the functional concentrated yogurt. It was established that the addition of 0.30-0.45% microencapsulated plant extracts caused the inhibition of the post-fermentation process, the improvement of the textural parameters of the yogurt during storage, thus the shelf life of the yogurt increased by seven days, compared to the yogurt simple. Mutual information analysis was applied to establish the correlation between the concentration of the encapsulated extracts on the sensory, physical-chemical, and textural characteristics of the yogurt.

Antioxidant activity of labneh made from cashew milk and its combination with cow or camel milk using different starter cultures.

The aim of this study is to investigate the effects of three strains of probiotic Lactobacillus spp. i.e. L. plantarum (S1) L. casei (S2), and/or L. rhamnosus (S3) in co-cultures with Streptococcus thermophiles (St) and L. delbrueckii subsp. lactis (Ll) on the changes of total phenolic and flavonoid contents, and antioxidant activity of concentrated yogurt (labneh; L) made from individual cashew milk (EwM; 100:0 v/v) mixed with/without cow (Co) or camel (Ca) milk (75:25v/v) during 0, 7, 14, and 21days of storage. EwML100% S3 showed the highest total phenolic and flavonoid contents during 21days of storage. Radical scavenging activity was improved in Ew-/Ca-ML (S2, S3, and S4) compared to control (containing St and Ll) on the 0thday. The maximum ferric reducing potential was observed in fresh Ew-/Ca-ML75% S1 (1.6 ± 0.05mM Fe + 2E/mL). All the starter cultures enhanced (p < 0.05) the chelating ability of EwML compared to control during the 7th and 14th day of storage. In conclusion, cashew milk labneh mixed with/without cow or camel milk containing probiotic Lactobacillus spp. can strengthen the health-promoting properties with antioxidant activity.

Caracterization and optimization of nonfat yogurt based on texture properties: instrumental texture profile and rheological properties

Milk fat plays an important role in the texture of yogurt. Thus, producing fat-free yogurt is a challenge for the food industry. We investigated and modeled the effect of yogurt composition and process parameters on the texture properties obtained by analyzing the texture profile analysis (TPA) and on the rheological properties. The experiment followed the Box-Behnken (DBB) design with three factors: centrifuge rotational speed (CRS) (3000, 4250 and 5500 rpm), casein (Cas) (3.4, 4.9 and 6.4% p/v) and transglutaminase enzyme (TgE) (0, 1 and 2 U/g of protein) concentrations. A complete second-order model better explained the effect of factors on texture properties. Desirability function was selected for the optimization of responses (firmness, cohesiveness and apparent viscosity placed at a maximum level and adhesiveness, gumminess, thixotropy and loss tangent (tan δ) were placed at a minimum level). The results suggest that the addition of TgE showed less effect on texture properties. The optimized values of each factor, Cas, TgE and CRS were, respectively, 3.4%, 1 U/g of protein and 5500 rpm with general desirability (D) of 0.6531. Under these conditions, it is possible to prepare a concentrated fat-free yogurt with a higher protein content due to the concentration, obtained after centrifugation, as well as obtaining desirable texture characteristics such as greater firmness and consistency, low gumminess and adhesiveness.

Microbiological profile of concentrated yoghurt manufactured from low and full fat milk during storage

The microbiological profile illustrates the existence and growth of microflora in fermentation products, such as concentrate yogurt. The study aimed to identify and evaluate microflora in yogurt paste observed from the total bacteria, total lactic acid bacteria (LAB), total yeast, LAB viability, and level of acidity. Concentrate yogurt was made of full-fat milk and low-fat milk that was fermented and hung for 24h and stored at a low temperature for observation on day 0,15, 30, 45, and 60. The data were subjected to a Generalized Linear Model (GLM) followed by the Duncan test. The result showed significant (P<0.05) changes in the total bacteria, total LAB, total yeast, LAB viability dan acidity (pH) of the fermentation products; however, no significant difference (P>0.05) was identified regarding the use of raw material. Storage made the fermented products suffer from the decreased total bacteria, LAB dan its viability, but there was an increase in the total yeast and pH. Conclusively, storing concentrate yogurt in a cool place for 60 would decrease the microflora profile (total bacteria, LAB dan LAB viability) but increase the total yeast and pH value.

Current goat milk production, characteristics, and utilization in Indonesia

In Indonesia and some southeast Asian countries, the number of goats raised for milk production is growing. In these countries, goat milk is the second most produced and consumed milk after cow milk. In Indonesia, dairy goats’ development is promising, but the farming of dairy goats and marketing milk products is still scattered and unstructured. The milk is produced from varieties of goat breeds, including Peranakan Etawa, Saanen, Nubian, and their crosses. Goat milk has unique and distinct characteristics and is an excellent source of nutrients for humans. Compared to cow milk, it has smaller fat globules, more homogenous, shorter rennet coagulation time, and softer curd. Goat milk utilization includes fluid milk for direct consumption; frozen fresh milk; dried or powdered milk; fermented milk products such as yogurt, kefir, including its derivatives such as cosmetics, concentrated yogurt, yogurt cheese, ice cream, shakes; cheeses such as fresh cottage-type cheese, acid-coagulated cheese and mozzarella; and also, other traditional products such as sweets & candies and caramels. The development of dairy goats and goat milk consumption is driven by several factors, including the low cost for start-up and production, consumers’ demand, alleged health properties of goat milk, and varieties of products.

A review of factors influencing the quality and sensory evaluation techniques applied to Greek yogurt.

Greek yogurt is one of the fastest growing products in the dairy industry. It is also known as strained yogurt, which is obtained after draining the whey. As a result of the draining process, Greek yogurt has higher total solids and lower lactose than regular yogurt. Since it is a concentrated yogurt, its sensory characteristics are different from regular yogurt. However, there is little information about factors influencing the quality of Greek yogurt and sensory evaluation techniques applied to Greek yogurt. This review aims to describe the effects of ingredients, starter cultures, processing techniques and other parameters on quality characteristics and sensory properties of Greek yogurt. In addition, advantages and limitations of novel sensory evaluation techniques applied to Greek yogurt products are discussed. In particular, we take a look at advanced techniques such as the electronic nose and electronic tongue and the benefits of these techniques with regard to Greek yogurt. This review should help the Greek yogurt industry to improve its current products and develop innovative products based on appropriate food evaluation techniques.

Quinoa flour as a skim milk powder replacer in concentrated yogurts: Effect on their physicochemical, technological, and sensory properties.

Milk standardization with solids (i.e., nonfat milk solids, MSNF) for yogurt manufacture is traditionally achieved by the addition of skim milk powder (SMP). However, the addition of SMP to milk‐based yogurt increases lactose content and decreases both protein content and gel firmness. Thus, in this work, quinoa flour (QF; 0%, 25%, 50%, 75%, and 100% w/w) was used to replace SMP in concentrated yogurt. The physicochemical, textural, and sensory properties and microstructure of the yogurt were evaluated during cold storage. Generally, protein content, water‐holding capacity, and L* value decreased, while syneresis, textural attributes, and viscosity increased with increasing QF content. The substitution of high levels of QF (>25%, w/w) for SMP led to significantly shorter fermentation times, as compared to the control sample. The scanning electron microscopy observations showed significant changes in the yogurt microstructure as a consequence of QF replacement. Samples with 25% (w/w) substitution of QF and control had the highest scores in overall acceptance. According to the results, QF could be applied as an interesting raw material for concentrating the milk‐based yogurt at substitution level of 25% (w/w).

Viability of selected strains of probiotic Lactobacillus spp. and sensory evaluation of concentrated yogurt (labneh) made from cow, camel, and cashew milk

The aim of this study is to investigate the effects of concentrated yogurt (labneh; L) made from cow (Co), camel (Ca), and cashew (Ew) milk (M) and their mixture (100% and 50%) using three strains of probiotic Lactobacillus spp. as starter culture (S) i.e. Lactobacillus plantarum (Lp; S1), L. casei (Lc; S2), L. rhamnosus (Lr; S3) or Lp, Lc, and Lr (S4) in co-cultures with Streptococcus thermophilus and L. delbrueckii subsp. Lactis on the changes of post-acidification and the viability of lactic acid bacteria (LAB) during 0, 7, 14, and 21 days of storage. In addition, sensory evaluation of all yogurt samples was run during the first day of storage. The lowest pH among all samples was seen in Ew-/Ca-ML50%S3 and Ew-/Co-ML50%S3 during the 21 days of storage. S. thermophilus increased to the highest numbers in Co-/Ca-ML50%S3 during 7th and 14th day as compared to other treated samples. All EwML100% were the most accepted by the panels compared to other samples. In conclusion, the combination of EwM with Co-/Ca-M during labneh preparation might enhance the viability of all different starter cultures especially S3 during the storage.

Understanding the fermentation factors affecting the separability of fermented milk: A model system study

The demand for high-protein fermented milk products is globally increasing. The effect of added starter culture, cutting pH and fermentation temperature on separability, i.e., how well curd and whey separate, were evaluated in a model system aiming to resemble Greek-style yoghurt. Skim milk was fermented with three commercial starter cultures at 39 °C or 43 °C to a pH of 4.45 or 4.60. Stirred fermented gels were concentrated to produce high-protein (~10%) fermented milk. The starter culture influenced the microstructure as well as the association (interactions) between exopolysaccharides (EPS) with the surface of the protein aggregates. The high association of EPS increased the viscosity and gel strength of the fermented model gels and decreased the zeta potential, the amount of whey removed as well as the protein and total solids concentration in the white mass. Increased fermentation temperature (from 39 °C to 43 °C) resulted in increased particle size and zeta potential values when EPS-producing starter cultures were applied. Cutting pH did not influence the separability of fermented stirred gels. The presence of EPS and pronounced association with protein increased the particle size, negative surface charge and structural rigidity, establishing a more stable system with reduced separability.

Optimization of concentrated yoghurt formulation containing skim milk, milk protein concentrate and soy flour using mixture design

Optimization of concentrated yoghurt formulation containing skim milk, milk protein concentrate and soy flour using mixture design

QUALITY ATTRIBUTES OF CONCENTRATED YOGURT (LABNEH) OF GOATS’ MILK FORMULATED WITH WHEY PROTEIN POWDER DURING STORAGE

Background: Whey is a by-product and a good source of milk proteins, lactose, some minerals such as calcium, and soluble vitamins, which make such a by-product, be considered as a source of valuable nutrients and act as a functional food. This study was carried out to investigate the quality attributes of concentrated yogurt (Labneh) made of goats’ milk and different concentrations of whey protein powder (WPP).&#x0D; Methods: Three different formulations were made by mixing goat milk with different concentrations of WPP (0, 5, and 10%) and stored for different periods (0, 10, and 21 days) at 4±1oC. Standard methods were applied to determine the Physico-chemical, microbiological, and sensory parameters of Labneh.&#x0D; Results: The addition of WPP caused an increase in yield, chemical composition especially protein content and total solids (TS) with the minor effect of the storage periods. The microbial load of labneh decreases with an increase in WPP concentration except for lactic acid bacteria but significantly (P ≤ 0.05) increased with the storage periods. The addition of WPP to goat milk improved organoleptic quality scores.&#x0D; Conclusion: The production of Labneh with both goats’ and WPP showed that this mixture is an interesting opportunity to have a product rich in nutrients and considered satisfactory by consumers

Determination of four priority polycyclic aromatic hydrocarbons (4PAHs) by GC-MS in traditional Turkish yoghurts

ABSTRACTPolycyclic aromatic hydrocarbons (PAHs) are ingested with foods and cause toxicities for humans. Yoghurt is one of the main foods that mediate PAH ingestion. Yanık yoghurt, a traditional strained yoghurt, can contain PAHs due to its production process. Therefore, the concentration and types of four polycyclic aromatic hydrocarbons were determined by gas chromatography-mass spectrometry (GC-MS). Yanık yoghurt samples were collected from different shops in Denizli, Turkey. For the method validation, the Eurachem guide (second edition) was adopted. Accordingly, linearity, working range, limits of detection (LOD), quantification (LOQ), precision and trueness values were set. Due to the selected validation parameters, the limit for detection was between 0.03 ng g−1and 0.05 ng g−1while the limit for quantification was between 0.10 ng g−1 and 0.16 ng g−1. Recovery rates higher than 83.80 % were obtained for four PAHs at two spiked concentrations (2.0 and 5.0 ng g−1). Five Yanık yoghurt samples and one commercial concentrated yoghurt sample were successfully analysed using the validated method.

Use of cinnamon, wheat germ, and eucalyptus oils to improve quality and shelf life of concentrated yogurt (Labneh)

Three essential oils, namely cinnamon, eucalyptus, and wheat germ were added to concentrated yogurt (Labneh) at a concentration of 600 μL\kg. The chemical, microbiological and organoleptic properti...

Yield and Processing Properties of Concentrated Yogurt Manufactured from Cow’s Milk: Effects of Enzyme and Thickening Agents

The objective of the experiment was to investigate the yield and processing properties of concentrated yogurt manufactured from local cow’s milk with the addition of microbial transglutaminase enzim (mTGase) and several thickening agents. Concentrated yogurt was manufactured from local fresh milk, which were previously processed into plain yogurt by adding starter culture of lactic acid bacteria. The enzyme and four thickening agents (pectin, carrageenan, xantan, and inulin) were added before the fermentation process. The amount of mTGase was 0.03% (w/w), while the amount of each thickening agent was 1.5g/100g of milk. Partial removal of whey was conducted by modified in-bag straining method using nylon bags. Data was analyzed by the procedure of generalized linear model. Overall, the present study showed that yield and the processing properties of concentrated yogurt can be improved by the addition of enzyme (mTGase) and thickening agents: inulin, carrageenan, xanthan, and pectin. The use of xanthan resulted in the highest yield, whereas the use of inulin and mTGase produce yogurt curd with low syneresis and high water holding capacity.

Optimization of labane (concentrated yogurt) formulation produced by wheyless process using mixture‐process variable experiments

In this study, the effect of milk protein concentrate (MPC), cheese whey powder (CWP) and konjac gum (KG) on physicochemical and rheological properties of labane was investigated. Physicochemical results showed that increasing MPC and decreasing CWP decreased pH (after fifth day) and syneresis. The results of the combination of back extrusion and texture profile analysis indicated that increasing KG significantly increased hardness, adhesiveness and adhesiveness force especially for samples with high amount of CWP but increasing MPC and decreasing CWP decreased cohesiveness in samples with high amount of KG. Strain sweep test of labane indicated that all sample had gel-like structure at 1 Hz and 20°C. Rheological results also showed that increasing KG significantly increased G′LVE, G″LVE, γc, τy, τf, and Gf especially for samples with high amount of CWP. At the optimized conditions, the predicted responses were determined as MPC 1.47%, CWP 6.52%, and KG 0.18%. Practical applications The physicochemical and rheological properties of products, such as labane, play an important role in processing and consumer acceptability. The determination of the optimum ingredients in formulation provides economic benefits and it can be useful for the food industries that want to use gums as thickening and stabilizing agents in the formulation of food products such as labane. Also mixture-process variable experiments are a quite effective mathematical approach for the optimization of the processing variables containing mixture components and process factors. So, it could be used efficiently to model the labane formulation.

Effect of Different Essential Oils on the Shelf Life of Concentrated Yogurt

Aims: The objective of this study is to use different essential oils (cinnamon, clove, rosemary, almond sweet, sesame, wheat germ, and cedar wood) in concentrated yoghurt as antimicrobial agents to increase shelf life of concentrated yoghurt.&#x0D; Place and Duration of Study: Department of Food Technology, Faculty of Science and Technology, Al-Quds University, Palestine, between January 2015 to August 2016.&#x0D; Methodology: Essential oils were added to concentrated yogurt at a concentration of 250 μl\kg. Antibacterial activity and properties of major borne bacteria such as total aerobic count bacteria, yeast, mold, Staphylococcus aureus, were evaluated by plate count method, (pouring plate method). All yogurt samples were sensory evaluated for flavor, body and texture, and appearance. Total solid content, and titratable acidity of different yogurt samples were also determined.&#x0D; Results: Total solids and pH of concentrated yogurt samples treated with essential oils were only slightly affected. The best three essential oils used in terms of influence on total bacterial viable count and mold count were found to be cinnamon, clove and rosemary. The most acceptable organoleptic properties of treated concentrated yogurt were those samples treated with sesame and rosemary oils.&#x0D; Conclusion: The addition of cinnamon, clove and rosemary essential oils could increase the shelf life of concentrated yogurt.

Evaluation of Good Manufacturing Practices in Small Dairy Plants in Jordan

The aim of this study was to assess the good manufacturing practices (GMPs) in small dairy plants in Jordan. In addition, the microbial product quality was used to assess the quality control practices in the production of concentrated yogurt (Labanah). The study was applied to 40 small dairy plants in the governorates of Irbid and Jerash, north of Jordan. Data were collected using a questionnaire, which consisted of a general information section besides two sections that addressed GMPs and the barriers to implementation of GMPs in the small dairy plants in Jordan. Assessment of GMPs was performed by using a structured questionnaire (checklist) that consisted of four sub-sections that addressed contemplating building, personnel, equipment, and food production. The mean overall score of implementation of GMPs in Irbid was 2.75, meaning that implementation of GMPs was low to moderate, while in Jerash it was 2.14, suggesting a low level of implementation of GMPs. Results showed that poor infrastructure and lack of financial resources were the most prominent obstacles to implementation of GMPs in the sample dairy plants in both governorates. The mean total counts of bacteria in the Labanah samples collected from the 40 dairy plants were 4.36 and 6.8 log 10 cfu/mL, respectively. All the Labanah samples showed negative results of salmonella and staphyllocccus . Contamination of the Labanah samples with yeast and molds, and coliform bacteria was an indicator of insufficient hygienic practices. Implementation of the food safety practices by the dairy producers is necessary. Keywords: Food safety, Labanah, Microbiological quality. DOI : 10.7176/FSQM/84-05