Survival and activity of selected probiotic organisms in set-type yoghurt during cold storage

Cross-over fermentation dynamics and proteomic properties of acid gels with indigenous Lactobacillus spp. isolated from cheeses

The present study examined the proteomic characteristics and fermentation dynamics of indigenous bacteria isolated from traditional Mihalic cheese in an acid gel matrix. Accordingly, autochthonous strains of Levilactobacillus brevis, Lacticaseibacillus paracasei, and Lacticaseibacillus rhamnosus were adapted to the gel matrix alongside commercial yogurt culture (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus). The study evaluated bacterial activity, proteolytic behavior, physicochemical characteristics, and textural and sensory properties in acid gel samples. The microorganisms demonstrated high survival rates (>7.35 log₁₀ cfu/g) in the fermented gel system and induced limited acidification throughout the product's shelf life. Regarding proteomic properties, the highest amino acid variation during the shelf life was observed in the FMB sample (28.20%). Furthermore, arginine, leucine, phenylalanine, aspartic acid, lysine, and cysteine reductions were noted in samples containing the isolated microorganisms. Including indigenous microorganisms in the fermented milk increased the levels of essential amino acids. Principal Component Analysis of sensory properties revealed that samples containing indigenous microorganisms differed significantly from the control sample (C), which contained only commercial yogurt culture. The results revealed the proteolytic changes associated with fermentation, including producing free amino acids as nutritional components, forming specific aroma compounds, and modifying textural and sensory properties. These results demonstrate the potential of utilizing local cultures to develop products enriched with novel bioactive components, offering consumers enhanced nutritional and sensory benefits.

Co-culturing Bifidobacterium animalis ssp. lactis with Lactobacillus helveticus accelerates its growth and fermentation in milk through metabolic interactions

This study aimed to investigate the interaction between Lactobacillus helveticus H9 (H9) and Bifidobacterium animalis ssp. lactis Probio-M8 (M8) through metabolomics analysis, focusing on understanding how co-culturing these strains can enhance bacterial growth and metabolism, thereby shortening the fermentation cycle and improving efficiency. The H9 and M8 strains were cultured individually and in combination (1:1 ratio) in milk. The fermented milk metabolomes were analyzed using solid-phase microextraction-gas chromatography-mass spectrometry. In the dual-strain fermentation, the M8 strain exhibited a 2.33-fold increase in viable bacterial count compared with single-strain fermentation. Additionally, the dual-strain fermentation resulted in greater metabolite abundance and diversity. Notably, the dual-strain fermented milk showed significantly elevated levels of metabolites, including 5-methyl-2-hexanone, (E)-3-octen-2-one, acetic acid, alanine, and 3-hydroxy-butanal. Our results demonstrated that co-culturing the M8 and H9 strains accelerated growth and fermentation efficiency. This enhancement effect is likely attributed to the strong proteolytic ability of the H9 strain, which hydrolyzes casein to produce small molecular peptides, alanine, tyrosine, and other growth-promoting factors. The insights gained from this study have significant implications for probiotics and the dairy industry, potentially leading to shorter fermentation cycles, enhanced cost-effectiveness, and improved nutritional and functional properties of future fermented milk products. Additionally, these findings may contribute to advancements in probiotic research and applications.

The Effect of Lactiplantibacillus plantarum SHY130 and Konjac Glucomannan on the Physicochemical, Antioxidant, and Sensory Properties of Stirred Yogurt

The impact of konjac glucomannan (KGM)-based synbiotics on yogurt quality is not well understood. This study investigated the effects of a synbiotic mixture of KGM and the selected probiotic Lactiplantibacillus plantarum SHY130 on the physicochemical, antioxidant, and sensory properties of yogurt. The results showed that KGM significantly promoted the growth of Lactiplantibacillus plantarum SHY130. The synbiotics dramatically enhanced the count of lactic acid bacteria in yogurt during the 14 days of storage. Texture analysis indicated that the synbiotic supplement had no impact on springiness and cohesiveness but resulted in notable reductions in hardness, gumminess, and chewiness. The synbiotics did not significantly affect the water-holding capacity and syneresis. While the synbiotics initially decreased yogurt viscosity, it increased with storage time. Furthermore, the synbiotics significantly improved the yogurt's antioxidant capacity. Additionally, the supplementation of the synbiotics did not adversely affect sensory properties, although the synbiotics containing 0.02% KGM negatively impacted overall acceptability. Overall, these findings elucidate the effects of KGM-based synbiotics on yogurt quality, providing a foundation for developing novel synbiotic yogurt products.

The effect of aqueous extract of Arctium lappa root on the survival of Lactobacillus acidophilus La-5 and Bifidobacterium bifidum Bb-12 and sensorial and physicochemical properties of synbiotic yogurt

The effect of aqueous extract of Arctium lappa root (ALE) on the survival of Lactobacillus acidophilus La-5 and Bifidobacterium bifidum Bb-12 probiotic bacteria and sensory and physicochemical properties of synbiotic yogurt was evaluated during 4 weeks storage at 4°C. According to this study, using 0.5% and 1% ALE significantly affected the survival of La-5 and Bb-12 during storage. The results showed that 1% of ALE counting of La-5 and Bb-12 has been reached from 6.96 and 8.14 Log CFU/g to 7.3 and 7.30 Log CFU/g after 28 days of storage. Moreover, adding 1% ALE to yogurt enhanced antioxidant activity and phenolic content to 1299.8 mg gallic acid/kg and 392.8 mg BHT eq./kg compared with the control (without extract) after storage, respectively. In general, in yogurt containing ALE, a decrease in Syneresis, undesirable changes in taste, texture, and appearance, and reduced overall acceptances were observed compared to the control. In conclusion, using this prebiotic compound (ALE) can improve nutritional properties and probiotic protection in yogurt during long time storage; thus, it is a good choice for application in the dairy industry.

Potential of Cheese-Associated Lactic Acid Bacteria to Metabolize Citrate and Produce Organic Acids and Acetoin

Lactic acid bacteria (LAB) are pivotal in shaping the technological, sensory, and safety aspects of dairy products. The evaluation of proteolytic activity, citrate utilization, milk pH reduction, and the production of organic compounds, acetoin, and diacetyl by cheese associated LAB strains was carried out, followed by Principal Component Analysis (PCA). Citrate utilization was observed in all Leuconostoc (Le.) mesenteroides, Le. citreum, Lactococcus (Lc.) lactis, Lc. garvieae, and Limosilactobacillus (Lm.) fermentum strains, and in some Lacticaseibacillus (Lact.) casei strains. Most strains exhibited proteolytic activity, reduced pH, and generated organic compounds. Multivariate PCA revealed Le. mesenteroides as a prolific producer of acetic, lactic, formic, and pyruvic acids and acetoin at 30 °C. Enterococcus sp. was distinguished from Lact. casei based on acetic, formic, and pyruvic acid production, while Lact. casei primarily produced lactic acid at 37 °C. At 42 °C, Lactobacillus (L.) helveticus and some L. delbrueckii subsp. bulgaricus strains excelled in acetoin production, whereas L. delbrueckii subsp. bulgaricus and Streptococcus (S.) thermophilus strains primarily produced lactic acid. Lm. fermentum stood out with its production of acetic, formic, and pyruvic acids. Overall, cheese-associated LAB strains exhibited diverse metabolic capabilities which contribute to desirable aroma, flavor, and safety of dairy products.

Lactic acid bacteria viability in different refrigerated food matrices: a systematic review and Meta‑analysis

The aim of this systematic review and meta-analysis was to determine which variables affect the viability of lactic acid bacteria (LAB) added to different types of refrigerated foods during the first 28 days. Scopus, ScienceDirect, PubMed and Cochrane Central Register of Reviews databases were searched from 1997 to April 2022. A total of 278 studies, which showed randomized and controlled experiments published in peer reviewed journals, were included. The viability of LAB in different moments during the storage process was synthesized as mean point estimate (MPE) via random-effects meta-analyses and the effect of multiple factors on the LAB´s viability was evaluated by multiple meta-regression. The meta-analysis showed that the decrease in LAB viability will be more abrupt the greater the initial dose. The physical structure of food may influence bacterial viability. Fruit was the type of product that most quickly lost viability. Co-culture of two or more species did not affect viability. Preservation methods had an unfavorable effect and prebiotics had a beneficial effect on bacterial viability. Viability was genus dependent. The data obtained in this study provide an overview of the factors to be taken into account for the design of new foods.

Fruit waste: a current perspective for the sustainable production of pharmacological, nutraceutical, and bioactive resources

Fruits are crucial components of a balanced diet and a good source of natural antioxidants, that have proven efficacy in various chronic illnesses. Various kinds of waste generated from fruit industries are considered a global concern. By utilizing this fruit waste, the international goal of "zero waste" can be achieved by sustainable utilization of these waste materials as a rich source of secondary metabolites. Moreover, to overcome this waste burden, research have focused on recovering the bioactive compounds from fruit industries and obtaining a new strategy to combat certain chronic diseases. The separation of high-value substances from fruit waste, including phytochemicals, dietary fibers, and polysaccharides which can then be used as functional ingredients for long-term health benefits. Several novel extraction technologies like ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), and supercritical fluid extraction (SFE) could provide an alternative approach for successful extraction of the valuable bioactives from the fruit waste for their utilization as nutraceuticals, therapeutics, and value-added products. Most of these waste-derived secondary metabolites comprise polyphenols, which have been reported to have anti-inflammatory, insulin resistance-treating, cardiovascular disease-maintaining, probiotics-enhancing, or even anti-microbial and anti-viral capabilities. This review summarizes the current knowledge of fruit waste by-products in pharmacological, biological, and probiotic applications and highlights several methods for identifying efficacious bioactive compounds from fruit wastes.

Comprehensive studies on the stability of yogurt-type fermented soy beverages during refrigerated storage using dairy starter cultures

Introduction

This study aimed to assess the feasibility of utilizing commercially available dairy starter cultures to produce yogurt-type fermented soy beverages and evaluate the fundamental properties of the resulting products.

Methods

Sixteen different starter cultures commonly used in the dairy industry for producing fermented milks, such as yogurt, were employed in the study. The study investigated the acidification curves, acidification kinetics, live cell population of starter microflora during refrigerated storage, pH changes, water-holding capacity, texture analysis, carbohydrates content, and fatty acid profile of the yogurt-type fermented soy beverage.

Results and Discussion

The results demonstrated that the starter cultures exhibited distinct pH changes during the fermentation process, and these changes were statistically significant among the cultures. The acidification kinetics of different cultures of lactic acid bacteria showed characteristic patterns, which can be used to select the most suitable cultures for specific product production. The study also revealed that the choice of starter culture significantly influenced the starter microorganisms population in the yogurt-type fermented soy beverage. Additionally, the pH values and water-holding capacity of the beverages were affected by both the starter cultures and the duration of refrigerated storage. Texture analysis indicated that storage time had a significant impact on hardness and adhesiveness, with stabilization of these parameters observed after 7-21 days of storage. Furthermore, the fermentation process resulted in changes in the carbohydrate content of the soy beverages, which varied depending on the starter culture used.

Shaping the Physicochemical, Functional, Microbiological and Sensory Properties of Yoghurts Using Plant Additives

Nowadays, consumers pay particular attention to the quality of the products they buy. They also expect a high level of innovation. Hence, the offer from the dairy sector is increasingly focusing on the use of various additives with proven health benefits. Many scientific teams from various regions of the world are engaged in research, and their aim is to identify plant additives that have beneficial effects on the human body. The aim of this article was to summarize the latest literature pertaining to the effects of plant additives used in the production of yoghurts on their physicochemical, functional, microbiological and sensory properties. It was found that a wide range of additives in a variety of forms are used in the production of yoghurts. The most common include fruits, vegetables, cereals, nuts, seeds, oils, plant or herbal extracts, fruit or vegetable fibre, and waste from fruit processing. The additives very often significantly affected the physicochemical and microbiological characteristics as well as the texture and sensory properties of yoghurt. As follows from the analysed reports, yoghurts enriched with additives are more valuable, especially in terms of the content of health-promoting compounds, including fibre, phenolic compounds, vitamins, fatty acids and minerals. A properly selected, high quality plant supplement can contribute to the improvement in the generally health-promoting as well as antioxidant properties of the product. For sensory reasons, however, a new product may not always be tolerated, and its acceptance depends mainly on the amount of the additive used. In conclusion, "superfood" yoghurt is one of the products increasingly recommended both preventively and as a way of reducing existing dysfunctions caused by civilization diseases, i.e., diabetes, cancer and neurodegenerative diseases. The studies conducted in recent years have not shown any negative impact of fortified yoghurts on the human body.

Effect of set-type yoghurt supplemented with the novel probiotic Lantiplantibacillus plantarum 200655 on physicochemical properties and the modulation of oxidative stress-induced damage

The present study developed a functional yoghurt supplemented with Lantiplantibacillus plantarum 200655 and evaluated its physicochemical properties and antioxidant activities. Yoghurt samples were prepared using commercial starter cultures and probiotics and grouped as follows: control sample without probiotics (C), GG (supplemented with Lacticaseibacillus rhamnosus GG), R (supplemented with L. plantarum KCTC 3108), and S (supplemented with L. plantarum 200655). The GG, R, and S samples had shorter fermentation time compared with the C sample. Lactic acid bacteria count, pH, and titratable acidity were similar in all samples during refrigerated storage. However, the GG, R, and S samples showed increased viscosity and water holding capacity (WHC), and decreased syneresis. The S sample had no adverse effect on organoleptic properties. Furthermore, the S sample had the highest antioxidant activity and significantly inhibited LPS-induced oxidative stress in intestinal cells. These findings suggest the potential use of L. plantarum 200655 in dairy products with therapeutic benefits.

Production and characteristic quality of probiotic Labneh cheese supplemented with broccoli florets

Purpose

The purpose of this study is to develop functional probiotic Labneh cheeses supplemented with broccoli florets.

Design/methodology/approach

Probiotic Labneh cheese was produced using broccoli florets paste at four different levels (0, 5, 10 and 15%), with Lactobacillus casei NRRL B-1922 as a probiotic strain, to evaluate its physicochemical, phenols, antioxidant activity, minerals, vitamins, textural, microbiological and sensory characteristics during storage for 15 days.

Findings

The results indicated that Labneh cheese with added broccoli paste exhibited significantly (p = 0.05) higher level of moisture, acidity, soluble nitrogen, phenols, antioxidant activity, minerals and B vitamins, and lower protein, fat, ash and pH values when compared to control Labneh cheese. Textural analysis of Labneh cheese indicated that Labneh with higher level of broccoli (15%) exhibited harder texture than others. Higher viable counts of Lactobacillus casei and Streptococcus thermophilus were detected in Labneh with broccoli paste, and the counts (107 cfu/g) were higher than the number should be present to achieve their health benefits. The most acceptable Labneh cheeses were those supplemented with 5 and 10% broccoli paste.

Originality/value

This study revealed broccoli florets could enhance the growth of Lactobacillus casei and Streptococcus thermophilus in the Labneh matrix, which resulted in a wider spectrum of health benefits of Labneh cheese to the consumers.

The impact of incorporating Lactobacillus acidophilus bacteriocin with inulin and FOS on yogurt quality

The current study aimed to figure out the effect of using a combination of 2% inulin, and 2% Fructo-oligosaccharides (FOS) with Lactobacillus acidophilus and their bacteriocin on some yogurt properties such as coagulation time, extending the shelf life of set yogurt and its microbiological quality, also the acceptance by consumers. The results indicated that coagulation time increased by 22.75% in yogurts prepared with Lactobacillus acidophilus and their bacteriocins compared to the control, and titratable acidity increased gradually in all treatments during storage. Hence control acidity (%) increased from 0.84 ± 0.02^A at zero time to 1.23 ± 0.03^A after 14 days of cold storage, while treatment (T4) was 0.72 ± 0.01^C at zero time and reached 1.20 ± 0.5^A after 39 days at the same conditions. The sensory properties showed the superiority of inulin, FOS, and Lactobacillus acidophilus bacteriocin groups. Lactobacillus bulgaricus, Streptococcus thermophiles, and Lactobacillus acidophilus count increased in the treatments compared to the control group, with an extended shelf life to 39 days of storage in the medicines containing lactobacillus acidophilus bacteriocin. Coliforms, Moulds, and yeasts did not detect in the treatments comprising 2% inulin, 2% FOS, and lactobacillus acidophilus bacteriocin for 39 days of refrigerated storage. This study proved that 2% inulin, 2% FOS, and Lactobacillus acidophilus bacteriocin fortification extended the shelf life by more than 5 weeks.

Stability and viability of synbiotic microgels incorporated into liquid, Greek and frozen yogurts

The viability of Lactobacillus acidophilus when co-encapsulated with fructooligosaccharides in alginate-gelatin microgels, for incorporation into liquid, Greek, and frozen yogurts, during storage and in vitro-simulated digestion was studied. Liquid yogurt provided the highest viability for the encapsulated probiotics during storage, followed by frozen and Greek formulations when compared to free probiotics, highlighting the influence of microencapsulation, yogurt composition, and storage conditions. Addition of up to 20% of probiotic (AG) and symbiotic (AGF) microgels did not cause significant changes in the liquid and frozen yogurts' apparent viscosity (η_ap ); however, it decreased η_ap for the Greek yogurt, indicating that microgels can alter product acceptability in this case. Both AG and AGF microparticles improved viability of cells face to gastric conditions for liquid and frozen yogurts, delivering cells in the enteric stage. Summarizing, liquid yogurt was the most appropriate for probiotic viability during storage, while frozen yogurt presented better protection along digestibility.

The Effect of Banana Fiber and Banana Peel Fiber on the Chemical and Rheological Properties of Symbiotic Yogurt Made from Camel Milk

Functional foods play an important role in human health by prevention of disease. A variety of functional foods are produced around the world. Recently, the consumption of dairy products containing probiotic bacteria and prebiotics (synbiotic) has increased. Yoghurt is the most common fermented dairy product. Various compounds are used to enrich yoghurt. One of these compounds is dietary fiber. Since the peel of fruits has a significant amount of fiber and is mainly disposed of as solid waste, so using the peel of fruits to extract fiber can not only solve environmental problems but also produce a cheap and useful source that leads to the production of dietary fiber. In this study, the effect of banana fiber and banana peel fiber at different concentrations (0, 0.2, 0.5, and 1%) on the chemical and rheological properties of synbiotic yogurt prepared from camel milk was investigated. The result showed that with increase of the amount of both fibers, pH, hydration, surface tension, overall acceptability, color, and flavor of the samples decreased significantly, but the viscosity, survival of probiotic bacteria (Lactobacillus casei and Lactobacillus gasseri), and texture acceptance increased significantly (p < 0.05). In conclusion, these fibers were able to reduce the syneresis of yogurt, which is one of the biggest disadvantages of yogurt, and help to increase health.

Effects of Fructose and Oligofructose Addition on Milk Fermentation Using Novel Lactobacillus Cultures to Obtain High-Quality Yogurt-like Products

The incorporation of prebiotics in fermented milk products is one of the best ways to promote health benefits while improving their sensory characteristics at the same time. The aim of this study was to evaluate the effects of the addition of fructose and oligofructose (1% and 2%) on the physicochemical, rheological, sensory, and microbiological quality attributes of fermented milk products inoculated with indigenous probiotic starter cultures of Lactobacillus isolated from Polish traditional fermented foods. The samples were evaluated during 35 days of refrigerated storage. The oligofructose and fructose caused increases in the populations of bacteria in comparison to the control fermented milk products without the addition of saccharides. The degrees of acidification in different fermented milk samples, as well as their viscosity, firmness, syneresis, and color attributes, changed during storage. The highest overall sensory quality levels were observed for the samples supplemented with L. brevis B1 and oligofructose. This study is the first attempt to compare the influences of different sugar sources on the physicochemical, rheological, sensory, and microbiological quality attributes of fermented milk products.

Novel approach for biosynthesizing of zinc oxide nanoparticles using Lactobacillus gasseri and their influence on microbiological, chemical, sensory properties of integrated yogurt

This research aimed to biosynthesizing zinc oxide nanoparticles (ZnO-NPs) using lactobacilli strains. All tested lactobacilli able to biosynthesis ZnO-NPs indicated by white precipitates. The characteristics of the biosynthesis ZnO-NPs from Lactobacillus gasseri were studied using UV-visible spectroscopy, TEM, SEM, DLS, FT-IR, XRD, and antimicrobial activity. The characteristic examination depicted cubic structures, pure and spherical ZnO-NPs with a diameter size of 22 nm. Antimicrobial study of ZnO-NPs displayed better higher antimicrobial activity on food pathogens in a dose-dependent manner. Moreover, integrated biosynthesis ZnO-NPs in yogurt positively affected the shelf life of yogurt during storage for four weeks without changes in the sensory evaluation. The microbiological population of fortified yogurt significantly reduced during storage than control. But chemically evaluation of fortified yogurt indicated an increase in dry matter, protein, and ash content than control. The achieved results suggested that the low amount of biosynthesized ZnO-NPs lead to the development of properties of integrated yogurt. Furthermore, the biosynthesized ZnO-NPs additive to yogurt could be a good food source for groups suffering from zinc deficiency such as the elderly groups or vegetarians who do not eat meat and at risk of zinc inadequacy.

Fortification of Acidophilus-bifidus-thermophilus (ABT) Fermented Milk with Heat-Treated Industrial Yeast Enhances Its Selected Properties

The improvement of milk dairy products' quality and nutritional value during shelf-life storage is the ultimate goal of many studies worldwide. Therefore, in the present study, prospective beneficial effects of adding two different industrial yeasts, Kluyveromyces lactis and Saccharomyces cerevisiae pretreated by heating at 85 °C for 10 min to be inactivated, before fermentation on some properties of ABT fermented milk were evaluated. The results of this study showed that the addition of 3% and 5% (w/v) heat-treated yeasts to the milk enhanced the growth of starter culture, Lactobacillus acidophilus, Bifidobacteria, and Streptococcus thermophilus, during the fermentation period as well as its viability after 20 days of cold storage at 5 ± 1 °C. Furthermore, levels of lactic and acetic acids were significantly increased from 120.45 ± 0.65 and 457.80 ± 0.70 µg/mL in the control without heat-treated yeast to 145.67 ± 0.77 and 488.32 ± 0.33 µg/mL with 5% supplementation of Sacch. cerevisiae respectively. Moreover, the addition of heat-treated yeasts to ABT fermented milk enhanced the antioxidant capacity by increasing the efficiency of free radical scavenging as well as the proteolytic activity. Taken together, these results suggest promising application of non-viable industrial yeasts as nutrients in the fermentation process of ABT milk to enhance the growth and viability of ABT starter cultures before and after a 20-day cold storage period by improving the fermented milk level of organic acids, antioxidant capacity, and proteolytic activities.

Chemical characterization of Cassia fistula polysaccharide (CFP) and its potential application as a prebiotic in synbiotic preparation

Prebiotics are non-digestible food ingredients that are selectively fermented by probiotics. The aim of this study was to investigate the chemical properties of a polysaccharide extracted from Cassia fistula mature fruit pulp and to evaluate its effects on probiotic strains: L. casei, L. rhamnosus, E. coli Nissle 1917 (EcN), and E. faecalis. These strains were compared for their growth behavior in culture media supplemented with different Cassia fistula polysaccharide (CFP) concentrations. The molecular weight of CFP was approximately 8.707 × 105 Da. The recovered polysaccharide contained a low percentage of crude protein (4.4%). Aspartic acid, glutamic acid, and proline were the most abundant amino acids. Glucose and mannose were the predominant sugars followed by arabinose and rhamnose. L. casei grew faster at high CFP concentrations (2%) compared with the lower concentrations of CFP. The highest values for the prebiotic index and prebiotic activity score were observed for L. casei treated with 2% CFP, and it may be considered a prebiotic due to its high resistance against α-amylase and acidic conditions. CFP provides two ways to adjust nitric oxide (NO) synthesis in macrophages. Finally, the use of 1.5 and 2% CFP for cultured milk production significantly shortened the fermentation period from 210 min to 180 min and 150 min, respectively.

Plant-Based Alternatives to Yogurt: State-of-the-Art and Perspectives of New Biotechnological Challenges

Due to the increasing demand for milk alternatives, related to both health and ethical needs, plant-based yogurt-like products have been widely explored in recent years. With the main goal to obtain snacks similar to the conventional yogurt in terms of textural and sensory properties and ability to host viable lactic acid bacteria for a long-time storage, several plant-derived ingredients (e.g., cereals, pseudocereals, legumes, and fruits) as well as technological solutions (e.g., enzymatic and thermal treatments) have been investigated. The central role of fermentation in yogurt-like production led to specific selections of lactic acid bacteria strains to be used as starters to guarantee optimal textural (e.g., through the synthesis of exo-polysaccharydes), nutritional (high protein digestibility and low content of anti-nutritional compounds), and functional (synthesis of bioactive compounds) features of the products. This review provides an overview of the novel insights on fermented yogurt-like products. The state-of-the-art on the use of unconventional ingredients, traditional and innovative biotechnological processes, and the effects of fermentation on the textural, nutritional, functional, and sensory features, and the shelf life are described. The supplementation of prebiotics and probiotics and the related health effects are also reviewed.

Effect of Simulated Gastrointestinal Tract Conditions on Survivability of Probiotic Bacteria Present in Commercial Preparations

Probiotics are recommended, among others, in the diet of children who are under antibiotic therapy, or that suffer from food allergies or travel diarrhea, etc. In the case of toddlers taking probiotic preparations, it is highly recommended to first remove the special capsule, which normally protects probiotic strains against hard conditions in the gastrointestinal tract. Otherwise, the toddler may choke. This removal can impair probiotic survival and reduce its efficacy in a toddler's organism. The aim of this study was to evaluate the survivability of five strains of lactic acid bacteria from the commercial probiotics available on the Polish market under simulated conditions of the gastrointestinal tract. Five probiotics (each including one of these strains: Bifidobacterium BB-12, Lactobacillus (Lb.) rhamnosus GG, Lb. casei, Lb. acidophilus, Lb. plantarum) were protective capsule deprived, added in a food matrix (chicken-vegetable soup) and subjected under simulated conditions of the gastric and gastrointestinal passage. Strain survivability and possibility to growth were evaluated. Obtained results showed that, among all analyzed commercial probiotic strains, the Lb. plantarum was the most resistant to the applied conditions of the culture medium. They showed a noticeable growth under both in vitro gastric conditions at pH 4.0 and 5.0, as well as in vitro intestinal conditions at all tested concentrations of bile salts.

Development of probiotic yogurt: effect of strain combination on nutritional, rheological, organoleptic and probiotic properties

Seven combinations of yogurt; C1 [yogurt starter culture (YSC)], T1, [YSC + Lactobacillus acidophilus (LA)], T2 [YSC + Bifidobacterium bifidum (BB)], T3 [YSC + Lactobacillus plantarum (LP)], T4 [YSC + Lactobacillus casei (LC)], T5 [YSC + LA + BB] and T6 [YSC + LP + LC] were developed. Nutritional [proximate and minerals], rheological [total soluble solids (TSS), pH, titratable acidity (TA), water holding capacity, synersis, viscosity] organoleptic and probiotic properties [viability, acid tolerance, bile salt tolerance] were assessed with standard methods. Nutritional composition differed significantly among samples except for the iron and zinc (P < 0.05). Yogurt containing LP as single or in combination with LC resulted in significantly higher ash, protein, calcium and phosphorous level. Probiotic combination also significantly affected the rheological properties of yogurts (P < 0.05). Yogurt with LP and LC as single or in combination lead to significantly higher TSS and viscosity while significantly low syneresis, whereas yogurt with LA as single or in combination resulted in low pH and high TA (P < 0.05). Interestingly, combination of LA and BB increased TSS, reduced pH and syneresis as compare to these bacteria as single probiotic source. Panel experts found yogurt with LP more flavourful. Combination of multi-strain and multi-species probiotic resulted in improved texture but we found no significant difference in overall acceptability. Combination of probiotic strains also resulted in better probiotic potential with multi-species combination found to be even more effective. BB seemed more stable than three other probiotic strains. The present study can be helpful to dairy industry in developing new probiotic products and may provide a rational for selecting a combination of probiotic strains.

Effect of faba bean and chickpea mucilage incorporation in the structure and functionality of kefir

This investigation aimed to investigate the viability of kefir enrichment with mucilage extracted from faba bean and chickpea. Four formulations of kefir were studied: fermented milk (control), milk with 3% of faba bean mucilage, milk with 3% of chickpea mucilage and milk with 3% of inulin from artichoke (as prebiotic control). Kefirs were evaluated during 28 days’ storage time at refrigerated temperature. Microbial viability, physicochemical properties (total titratable acidity, syneresis and pH), rheological properties (flow and dynamic shear rheology) and consumer’s acceptability were evaluated. The number of bacteria significantly increased during storage period in all the formulations. The pH decreases during storage whereas total titratable acidity increased as was expected. Kefir supplemented with mucilage showed slightly lower but not significantly different sensory acceptability scores in comparison to the control. The novel mucilage ingredients could be prebiotic source for improving kefir quality.

Sensory, Microbiological and Physicochemical Characterisation of Functional Manuka Honey Yogurts Containing Probiotic Lactobacillus reuteri DPC16

Consumer acceptance of synbiotics, which are synergistic combinations of probiotics and their prebiotic substrates, continues to expand in the functional food category. This research aimed at evaluating the effect of antibacterial manuka honey on the probiotic growth and sensory characteristics of potentially synbiotic yogurts manufactured with Lactobacillus reuteri DPC16. Probiotic viable count in yogurts with 5% w/v Manuka honey (Blend, UMF^TM 18⁺, AMF^TM 15⁺ and AMF^TM 20⁺) was evaluated by the spread plate method over the refrigerated storage period of three weeks. A panel of 102 consumers preferred the yogurt made with invert syrup over the manuka honey variants, and the unsweetened control was least liked overall. Invert syrup yogurt was also the most effective in promoting the growth of the probiotic lactobacilli. However, the honey-sweetened yogurts had a more favourable fermentation metabolite profile, especially the lactic and propionic acids, as estimated by nuclear magnetic resonance (NMR) analyses. The probiotic counts in AMF^TM 15⁺ manuka honey yogurt (7 log cfu/mL) were significantly higher than the other honey yogurt types (Manuka Blend and UMF^TM 18⁺) and above the recommended threshold levels. The combination thus can be developed as a synbiotic functional food by further improving the sensory and physicochemical properties such as texture, apparent viscosity and water holding capacity.

Effects of Frozen Storage on Viability of Probiotics and Antioxidant Capacities of Synbiotic Riceberry and Sesame-Riceberry Milk Ice Creams

According to many recent studies, ice cream was found to be an effective carrier of probiotics along the human gastrointestinal tract. While probiotics have long been known to improve gut health, prebiotic-supplemented ice creams have demonstrated properties that could be linked to various health benefits and improvement of the gut microbiota. In this study, riceberry and sesame-riceberry milk ice creams were supplemented with inulin, Lactobacillus casei 01 and Lactobacillus acidophilus LA5 to examine the changes of probiotic populations in different formulations of ice cream. The survivability of probiotics after 60 days of frozen storage and the level of viable cell tolerance towards the simulated gastrointestinal environment were also assessed, followed by sensory evaluation with 100 untrained panelists and determination of chemical qualities of ice cream samples. Findings revealed L. casei 01 to be more resistant to frozen storage compared to L acidophilus LA5, whereas addition of sesame milk and inulin were shown to minimize levels of viable cell loss following environmental and mechanical stress, suggesting enhanced probiotic activity. Significant reductions in probiotic viability were observed for all ice cream samples, however higher survival rates were observed in prebiotic-supplemented samples prior to and after 60 days of frozen storage. Probiotic cell counts in all samples exceeded the minimum recommended value (6 log CFU/g). In simulated gastric and bile fluid, all samples illustrated a significant change in probiotic levels, which significantly decreased with increase time of exposure to acidic and basic conditions. Probiotic strains in samples containing riceberry, sesame and inulin demonstrated greatest survivability as observed by reduction in pH and increased total acidity, with increased antioxidant and phenolic contents. On the other hand, changes in physicochemical properties of ice cream lowered overall sensory scores in terms of color and flavor. This study contributes to future development and applications of riceberry and sesame for inducement of synbiotic effects in novel probiotic products.

Studying the Influence of Apple Peel Polyphenol Extract Fortification on the Characteristics of Probiotic Yoghurt

The aim of the current study was to evaluate the effect of apple peel polyphenol extract (APPE) on the physicochemical and microbiological properties of probiotic yoghurt. Five concentrations of APPE were added in probiotic yoghurt as: (1) CTL, control without APPE; (2) AE1, addition of 1% APPE; (3) AE2, addition of 2% APPE; (4) AE3, addition of 3% APPE; (5) AE4, addition of 4% APPE; and (6) AE5, addition of 5% APPE. The prepared probiotic yoghurt was stored at 4 °C for 21 days and analyzed for physicochemical and microbiological properties. The initial viable count of L. bulgaricus, S. thermophilus, B. lactis and L. acidophilus were similar in all yoghurt samples at day 1. The maximum viability loss of probiotics was observed in CTL (p < 0.05). The lowest viability loss of probiotics was observed in AE5 samples (p < 0.05). The acidity, water holding capacity and viscosity were increased with the addition of APPE. No significant effects were observed on milk fat and total solid contents of probiotic yoghurt with the addition of APPE. The total phenolic contents of probiotic yoghurt increased significantly as 0.59, 0.71, 0.97, 1.18, 1.35 in AE1, AE2, AE3, AE4 and AE5, samples respectively. It was observed that AE3 and AE4 samples had better taste, flavour and colour with good texture. The survival of probiotics and antioxidant activity of the yoghurts were enhanced with the addition of APPE. In conclusion, apple peels could be successfully used as prebiotic in yoghurt with increased viable counts of probiotics.

Jujube mucilage as a potential stabilizer in stirred yogurt: Improvements in the physiochemical, rheological, and sensorial properties

Here, the mucilage of jujube was extracted and used as a natural stabilizer in the production of stirred yogurt. Yogurts were enriched with different concentrations of jujube mucilage (i.e., 0, 0.1, 0.15, and 0.2%), and their physical, chemical and sensory attributes were analyzed during 21 days of storage at 4°C. The results showed that the protein and fat contents of the yogurts were not significantly different compared with each other, while higher ash contents were obtained in yogurts which contained higher concentrations of the mucilage. The acidity and proteolysis of the stirred yogurts were enhanced in the presence of mucilage, and they exhibited lower concentrations of diacetyl and acetaldehyde, although the differences were not significant among the samples of different treatments. The storage time had adverse and direct effects on the amounts of acetaldehyde and diacetyl, respectively. The effects of storage time and the presence of jujube mucilage in yogurts caused a significant decrease in the percentage of syneresis, while their viscosity and WHC values increased. The magnitudes of dynamic moduli (G, G''), complex viscosity (η*), and loss tangent (tan δ) of stirred yogurts increased by increasing the concentration of jujube mucilage. The yogurts which had been enriched with mucilage were preferred slightly less by tasters during the storage period, but these differences did not amount to a statistical significance. Generally, the results of the present study showed that the jujube mucilage can be potentially used as a natural stabilizer in stirred yogurt.

Physicochemical and Microbiological Properties of Synbiotic Yogurt Made with Probiotic Yeast Saccharomyces boulardii in Combination with Inulin

Saccharomyces boulardii is a unique species of yeast previously characterized as a probiotic strain (CNCM I-745) among a few probiotic yeasts reported to date. Inulin is one of the most common prebiotics that exhibit twisted hydrocolloidal properties in dairy products. The present study was designed to develop a synbiotic yogurt by incorporation of S. boulardii and inulin at 1%, 1.5%, and 2% (w/v), comparing with the probiotic and control plain yogurts. Microrheological, microstructural, microbiological, sensory properties, and volatile compounds of the yogurt samples were evaluated. Microrheological analysis showed that addition of inulin to yogurt slightly reduced the values of G' and G″, while solid-liquid balance (SLB) values confirmed more solid properties of the synbiotic yogurt (0.582~0.595) than the plain yogurt (0.503~0.518). A total of 18 volatile compounds were identified in the synbiotic yogurt, while only five and six compounds were identified in plain and probiotic yogurts, respectively. Physiochemical parameters such as pH, acidity, and protein content were in the normal range (as with the control), while fat content in the synbiotic yogurt decreased significantly. Addition of 1% inulin not only reduced syneresis but also maintained viability of S. boulardii after 28 days of storage. Microstructural and microrheological studies confirmed the dense, compressed, homogeneous structure of the synbiotic yogurt. Thus, addition of inulin improved the textural and sensory properties of the synbiotic yogurt, as well as survival of S. boulardii with viable count above 6.0 log CFU/g in yogurt, as generally required for probiotics. Therefore, novel synbiotic yogurt with desirable quality was developed as an effective carrier for delivery of the probiotic yeast exerting its beneficial health effects.

Impact of Milk Fortification on the Microbiological and Physicochemical Properties of Set-Type Skimmed Yoghurt Using Three Commercial Soluble Prebiotics

The impact of milk fortification on the microbiological and physicochemical properties of a set-type skimmed yoghurt using three commercial soluble prebiotics (inulin, iso-malto-oligosaccharides, and xylo-oligosaccharides) at either 3 or 5 g/kg was assessed. The three prebiotics had an insignificant impact on yoghurt fermentation because all yoghurt samples had similar titratable acidity and similar pH values after their lactic acid fermentation. Regarding the control yoghurt samples without prebiotics usage, the prebiotics-fortified yoghurt samples showed no difference in their main chemical compositions, hardness, syneresis extent, and apparent viscosity (p > 0.05), but had a slightly higher lactic acid content and a viable quantity of starter strains. All yoghurt samples had the same acetic acid content, while propionic and butyric acids were not produced. Yoghurt storage at 4 C for 21 d gave these yoghurt samples decreased pH values and a viable quantity of starter strains (especially Lactobacillus delbrueckii subsp. bulgaricus) and unchanged acetic acid; however, it increased lactic acid contents. Overall, prebiotics fortification up to 5 g/kg had a completely insignificant impact on the fermentation and quality attributes of yoghurt samples but could possibly improve the health of consumers due to higher dietary fibers and starter strain populations.

Use of Fish Oil Nanoencapsulated with Gum Arabic Carrier in Low Fat Probiotic Fermented Milk

Fish oil consists of omega-3 fatty acids which play an important role in human health. Its susceptibility to oxidation causes considerable degradation during the processing and storage of food products. Accordingly, encapsulation of this ingredient through freeze drying was studied with the aim of protecting it against environmental conditions. Gum arabic (GA) was used as the wall material for fish oil nanoencapsulation where tween 80 was applied as the emulsifier. A water-in-oil (W/O) emulsion was prepared by sonication, containing 6% fish oil dispersed in aqueous solutions including 20% and 25% total wall material. The emulsion was sonicated at 24 kHz for 120 s. The emulsion was then freeze-dried and the nanocapsules were incorporated into probiotic fermented milk, with the effects of nanocapsules examined on the milk. The results showed that the nanoparticles encapsulated with 25% gum arabic and 4% emulsifier had the highest encapsulation efficiency (EE) (87.17%) and the lowest surface oil (31.66 mg/100 kg). Using nanoencapsulated fish oil in fermented milk significantly (p<0.05) increased the viability of Lactobacillus plantarum as well as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) contents. The fermented milk sample containing fish oil nanoencapsulated with 25% wall material and 4% emulsifier yielded the greatest probiotic bacterial count (8.41 Log CFU/mL) and the lowest peroxide value (0.57 mEq/kg). Moreover, this sample had the highest EPA and DHA contents. Utilizing this nanoencapsulated fish oil did not adversely affect fermented milk overall acceptance. Therefore, it can be used for fortification of low fat probiotic fermented milk.