Assessment of Freeze-Dried Immobilized Lactobacillus casei as Probiotic Adjunct Culture in Yogurts

Pro-pre and Postbiotic Fermentation of the Dietetic Dairy Matrix with Prebiotic Sugar Replacers

In this study, bacterial growth, postbiotic short-chain fatty acids (SCFAs) formation, and gelation properties of sugar-free probiotic milk gels produced with stevia and inulin as a sugar replacer and synbiotic interactions were investigated with regard to prebiotic/bio-therapeutic potential and consumer preference. Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis cultures were used in the manufacture of dietetic milk gels. The addition of stevia and inulin promoted the viability of bacteria and enhanced milk gel firmness throughout its shelf life. The activity of the probiotic bacteria was identified to be within the potential prebiotic effects (> 8.30 log10 cfu mL-1) in a food matrix. However, it was determined that especially stevia and stevia + inulin addition increased the survival rate of probiotic bacteria and in vitro total SCFA production with higher scores for consumers' preferences rather than with the addition of stevia alone. Yoghurts containing B. animalis subsp. lactis have improved the instrumental textural properties, whereas yoghurts containing L. acidophilus had higher scores for sensorial attributes.

Comparison and effect of plain and calcium fortified yogurt on glycemic responses, anthropometrics and metabolic biomarkers

Metabolic syndromes including obesity and diabetes are the most common health issues due to insulin resistance, disturbance in glucose homeostasis, lack of exercise, and improper diet. The current study was planned to evaluate the potential effects of regular diet with fortified yogurt on blood glycemia and anthropometric responses. Plain yogurt was procured from the local market, and then it was fortified with calcium. Furthermore, the subsequent effect of fortified yogurt on blood glucose, insulin, and anthropometric measurements was assessed at different time intervals. A total of 40 healthy females and males aged about 20 years with a normal BMI range (20-24.9 kg/m2) were recruited within the Government College University Faisalabad. Participants filled out the habits Performa, stress factors questionnaire, and activity questionnaire. Blood glucose (BG) and visual analogous scale (VAS) performs were also taken in the fasting stage and then assigned treatment was given. After 15, 30, 45, 60, 90, and 120 min intervals VAS and BG estimation was carried out. The results shows that fortified yogurt contained a higher amount of calcium. Likewise, a similar trend was observed for the desire to eat, a feeling of fullness, palatability, physical comfort, and overall acceptability. The results obtained from various analyses were statistically evaluated.

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.

Physicochemical, sensory, and antioxidant characteristics of stirred-type yogurt enriched with Lentinula edodes stipe powder

The Lentinula edodes stipe (LES), a by-product of L. edodes fruiting body processing, is rich in dietary fiber, protein, and polysaccharides, which can be served as the functional ingredient in dairy products. In this study, stirred yogurts fortified with 1%, 2%, and 3% LES were prepared, and the effects of LES on the changes in color, pH, titratable acidity (TA), viable lactic acid bacteria (LAB) cells, syneresis, viscosity, texture, and antioxidant activity of the flavored yogurt were monitored at the beginning and the end of storage. The LES decreased the lightness, increased the red-green color values and yellow-blue color values, decreased the pH values, and increased the contents of TA, the viable LAB cells, and the antioxidant activity of yogurt samples in a dose-dependent manner. The addition of LES showed double-edged effects on the texture of yogurt, which significantly reduced firmness and viscosity but decreased the syneresis. Compared with plain yogurt, the 2% LES-fortified yogurt exhibited similar index values of texture parameters and higher scores of the appearance, fermented odor, taste quality, and overall acceptance, suggesting that this might be the optimal dose for industrial production. After cold storage for 28 days, pH values of all yogurt samples further decreased with increasing of TA. Interestingly, syneresis of LES-fortified yogurt decreased and the viable LAB cells and antioxidant activity of 3% LES-fortified yogurt slightly decreased. Therefore, LES is beneficial to improve physicochemical, sensory, and antioxidant properties of yogurt, which has the potential to be used in functional dairy products.

Novel Functional Grape Juices Fortified with Free or Immobilized Lacticaseibacillus rhamnosus OLXAL-1

During the last decade, a rising interest in novel functional products containing probiotic microorganisms has been witnessed. As food processing and storage usually lead to a reduction of cell viability, freeze-dried cultures and immobilization are usually recommended in order to maintain adequate loads and deliver health benefits. In this study, freeze-dried (free and immobilized on apple pieces) Lacticaseibacillus rhamnosus OLXAL-1 cells were used to fortify grape juice. Juice storage at ambient temperature resulted in significantly higher (>7 log cfu/g) levels of immobilized L. rhamnosus cells compared to free cells after 4 days. On the other hand, refrigerated storage resulted in cell loads > 7 log cfu/g for both free and immobilized cells for up to 10 days, achieving populations > 109 cfu per share, with no spoilage noticed. The possible resistance of the novel fortified juice products to microbial spoilage (after deliberate spiking with Saccharomyces cerevisiae or Aspergillus niger) was also investigated. Significant growth limitation of both food-spoilage microorganisms was observed (both at 20 and 4 °C) when immobilized cells were contained compared to the unfortified juice. Keynote volatile compounds derived from the juice and the immobilization carrier were detected in all products by HS-SPME GC/MS analysis. PCA revealed that both the nature of the freeze-dried cells (free or immobilized), as well as storage temperature affected significantly the content of minor volatiles detected and resulted in significant differences in the total volatile concentration. Juices with freeze-dried immobilized cells were distinguished by the tasters and perceived as highly novel. Notably, all fortified juice products were accepted during the preliminary sensory evaluation.

Exploring the Potential of Sustainable Acid Whey Cheese Supplemented with Apple Pomace and GABA-Producing Indigenous Lactococcus lactis Strain

This study aimed to utilize two by-products, acid whey and apple pomace, as well as an indigenous Lactococcus lactis LL16 strain with the probiotic potential to produce a sustainable cheese with functional properties. Acid whey protein cheese was made by thermocoagulation of fresh acid whey and enhancing the final product by adding apple pomace, L. lactis LL16 strain, or a mixture of both. The sensory, the physicochemical, the proteolytic, and the microbiological parameters were evaluated during 14 days of refrigerated storage. The supplementation of the cheese with apple pomace affected (p ≤ 0.05) the cheese composition (moisture, protein, fat, carbohydrate, and fiber), the texture, the color (lightness, redness, and yellowness), and the overall sensory acceptability. The addition of the presumptive probiotic L. lactis LL16 strain decreased (p ≤ 0.05) the concentration of glutamic acid, thus increasing γ-aminobutyric acid (GABA) significantly in the acid whey cheese. The supplementation with apple pomace resulted in slightly (p < 0.05) higher counts of L. lactis LL16 on day seven, suggesting a positive effect of apple pomace components on strain survival. The symbiotic effect of apple pomace and LL16 was noted on proteolysis (pH 4.6-soluble nitrogen and free amino acids) in the cheese on day one, which may have positively influenced the overall sensory acceptance.

Novel Probiotic/Bacterial Cellulose Biocatalyst for the Development of Functional Dairy Beverage

The development of innovative functional products with potential health benefits, under the concept of bio-economy, is flourishing. This study undertook an evaluation of non-dairy lactobacilli Lactiplantibacillus pentosus B329 and Lactiplantibacillus plantarum 820 as “ready to use” starter cultures. Lactic acid bacteria (LAB) cultures were evaluated for their fermentation efficiency, before and after freeze-drying, using cheese whey (CW) as a fermentation substrate and subsequent immobilization on bacteria cellulose (BC) to produce a novel biocatalyst. The biocatalyst was applied in functional sour milk production and compared with free cells via the assessment of physicochemical and microbiological properties and sensory evaluation. Evidently, LAB strains exhibited high fermentative activity before and after freeze-drying. Results of a 5-month storage stability test showed that viability was 19% enhanced by immobilization on BC, supporting the concept of “ready to use” cultures for the production of fermented beverages. Likewise, sour milk produced by the BC biocatalyst presented higher organoleptic scores, compared to the free cells case, whereas immobilization on BC enhanced probiotic viability during post-fermentation storage (4 °C, 28 days). The obtained high viability (>107 log cfu/g) demonstrated the efficacy of the proposed bioprocess for the production of functional/probiotic-rich beverages. Ultimately, this work presents a consolidated scheme that includes the advantages and the cooperative effect of probiotic LAB strains combined with a functional biopolymer (BC) towards the formulation of novel functional products that coincide with the pillars of food systems sustainability.

Inoculum size of co-fermentative culture affects the sensory quality and volatile metabolome of fermented milk over storage

Lacticaseibacillus paracasei PC-01 is a probiotic candidate isolated from naturally fermented yak milk in Lhasa, Tibet, and it has been shown to possess excellent milk fermentation properties. This study used Lacticaseibacillus paracasei PC-01 as a co-fermentation strain to investigate the effect of inoculum size with a commercial starter in milk fermentation on the product flavor and profile of volatile metabolites over 28 d of cold storage. Lacticaseibacillus paracasei PC-01 was allowed to ferment in pasteurized milk with or without the commercial starter (YF-L904) at 42°C until the pH decreased to 4.5. The finished fermented milks were stored at 10°C for 28 d. Milk samples were taken at hour 0 (before fermentation) and then at d 1, 14, and 28 of cold storage. Different inoculum sizes of Lacticaseibacillus paracasei PC-01 had no significant effect on pH or titratable acidity during storage of fermented milk. Viable counts of strain PC-01 continued to increase during cold storage of the fermented milk. Generally, as storage of fermented milk proceeded, the overall sensory quality score decreased in all groups. However, the overall sensory scores of PC-01-M were generally higher than those of other groups, suggesting that a medium dose of Lacticaseibacillus paracasei PC-01 had the most obvious effect of slowing the decline in sensory quality of fermented milk during storage. Changes in sensory scores and consumer preferences were accompanied by increases in both the quantity and variety of key volatile metabolites in fermented milk during fermentation, post-ripening (d 1), and storage. Major differentially abundant metabolites, including acetaldehyde, methyl ketones, medium-chain and short-chain fatty acids, 2,3-butanedione, and acetoin, were enriched in fermented milks rated highly in the sensory evaluation. Our data confirmed that the inoculum size of co-fermentative culture affected the sensory quality and volatile metabolome of fermented milk over storage, and an optimal range of co-fermentative culture was titrated in this work.

Algicidal Bacteria: A Review of Current Knowledge and Applications to Control Harmful Algal Blooms

Interactions between bacteria and phytoplankton in aqueous ecosystems are both complex and dynamic, with associations that range from mutualism to parasitism. This review focuses on algicidal interactions, in which bacteria are capable of controlling algal growth through physical association or the production of algicidal compounds. While there is some evidence for bacterial control of algal growth in the field, our understanding of these interactions is largely based on laboratory culture experiments. Here, the range of these algicidal interactions is discussed, including specificity of bacterial control, mechanisms for activity, and insights into the chemical and biochemical analysis of these interactions. The development of algicidal bacteria or compounds derived from bacteria for control of harmful algal blooms is reviewed with a focus on environmentally friendly or sustainable methods of application. Potential avenues for future research and further development and application of bacterial algicides for the control of algal blooms are presented.

Innovative and Healthier Dairy Products through the Addition of Microalgae: A Review

In recent years, the development of healthier foods, richer in nutraceutical or functional compounds, has been in great demand. Microalgae are attracting increasing attention, as their incorporation in foods and beverages can be a promising strategy to develop sustainable foods with improved nutritional profiles and a strong positive impacts on health. Despite the increasing market demand in plant-based foods, the popularity of fermented dairy foods has increased in the recent years since they are a source of microorganisms with health-promoting effects. In this context, the incorporation of microalgae in cheeses, fermented milks and other dairy products represents an interesting approach towards the development of innovative and added-value hybrid products based on animal proteins and enriched with vegetable origin ingredients recognized as extremely valuable sources of bioactive compounds. The effect of the addition of microalgal biomass (Chlorella vulgaris, Arthrospira platensis, Pavlova lutheri, and Diacronema vlkianum, among others) and its derivates on the physicochemical composition, colorimetric and antioxidant properties, texture and rheology behavior, sensory profile, and viability of starter cultures and probiotics in yogurt, cheese and ice cream is discussed in the current work. This review of the literature on the incorporation of microalgae in dairy products aims to contribute to a better understanding of the potential use of these unique food ingredients in the development of new sustainable products and of their beneficial effects on health. Considering the importance of commercialization, regulatory issues about the use of microalgae in dairy products are also discussed.

Effect of Immobilization Support and Fermentation Temperature on Beer and Fermented Milk Aroma Profiles

The food industry increasingly produces wastes like coconut and peanut shells. In addition, low temperature fermentation is always a challenge. Therefore, in the present study, a sustainable exploitation of these by-products is proposed through the production of carriers for immobilized cells of yeast and bacteria. The immobilized cells, after thermally drying, were evaluated for their efficiency in beer and milk fermentations respectively, in various fermentation temperatures and storage for up to three months. The beers and fermented milks were evaluated for their aroma and the results showed products of high quality. Coconut shells resulted in better products with increased fruity ester content in fermented milks and reduced dimethyl sulfite and vicinal diketones and increased ratio of esters to alcohol in beers. These results reveal the possibilities of immobilized cells in coconut and peanut shells for application in food industry, however, more research is needed to evaluate their effect on sensory characteristics and possible prebiotic and probiotic potential especially in the case of fermented milks.

Tarkhineh as a new microencapsulation matrix improves the quality and sensory characteristics of probiotic Lactococcus lactis KUMS-T18 enriched potato chips

In the present study, probiotic potato chips containing a newly isolated probiotic Lactococcus lactis KUMS-T18 strain were produced by using a simple spraying method and then enhancing the stability, survival rate, and sensory characteristics of product during storage at 4 °C and 25 °C was examined for four months. Based on the results, Lactococcus lactis KUMS-T18 isolated from traditional Tarkhineh as a safe strain had high tolerance to low pH and high bile salt, anti-pathogenic activity, hydrophobicity, adhesion to human epithelial cells, auto- and co-aggregation, cholesterol assimilation and antibiotic susceptibility. Meanwhile, by micro-coating the probiotic cells in Tarkhineh formulations, elliptical to spherical shape (460-740 µm) probiotic drops were produced. The results revealed that potato chips produced with turmeric and plain Tarkhineh during storage at 4 °C, had excellent protection abilities for probiotic cells with about 4.52 and 3.46 log decreases in CFU/g respectively. On the other hand, probiotic potato chips, compared to non-probiotic and commercial potato chips, showed the criteria of probiotic products such as excellent quality and superior sensory characteristics. In summary, this study proved that probiotic Lactococcus lactis KUMS-T18 strain covered by Tarkhineh formulations as protective matrix has high potential to be used in the production of probiotic potato chips.

Probiotics in the dairy industry-Advances and opportunities

The past two decades have witnessed a global surge in the application of probiotics as functional ingredients in food, animal feed, and pharmaceutical products. Among food industries, the dairy industry is the largest sector where probiotics are employed in a number of dairy products including sour/fermented milk, yogurt, cheese, butter/cream, ice cream, and infant formula. These probiotics are either used as starter culture alone or in combination with traditional starters, or incorporated into dairy products following fermentation, where their presence imparts many functional characteristics to the product (for instance, improved aroma, taste, and textural characteristics), in addition to conferring many health-promoting properties. However, there are still many challenges related to the stability and functionality of probiotics in dairy products. This review highlights the advances, opportunities, and challenges of application of probiotics in dairy industries. Benefits imparted by probiotics to dairy products including their role in physicochemical characteristics and nutritional properties (clinical and functional perspective) are also discussed. We transcend the traditional concept of the application of probiotics in dairy products and discuss paraprobiotics and postbiotics as a newly emerged concept in the field of probiotics in a particular relation to the dairy industry. Some potential applications of paraprobiotics and postbiotics in dairy products as functional ingredients for the development of functional dairy products with health-promoting properties are briefly elucidated.

Yogurts Supplemented with Juices from Grapes and Berries

Nowadays, there is growing interest for the development of enriched dairy products with phenolic compounds derived from edible sources, mainly due to their safety and potential health benefits. Following that trend, in the present study, fruit juices (blueberry, aronia, and grape) were supplemented into yogurt as functional ingredients. The main physicochemical characteristics (pH, reducing sugars, acidity, color, and syneresis), total phenolic content, antioxidant activity, and viability of yogurt starters were monitored during production and storage. The use of juices had no significant effect on milk acidification rate and on the main physicochemical characteristics of yogurts, while resulted in increased red color. Total phenolic content increased from 30 to 33% (grape and aronia) and up to 49% (blueberry), while similar results were observed in antioxidant activity. Similar values of syneresis were presented in all yogurts, probably due to exopolysaccharide producing starter culture. Streptococcus thermophilus retained high viable counts during storage especially in yogurts with fruit juices (>10⁸ cells g⁻¹) revealing a possible prebiotic effect of juices. The results obtained from this study show that fruit juices (aronia, blueberry, and grape) have potential to be used in yogurt production in order to optimize the benefits of probiotic products with high phenolic compound intake.

Lyophilized Probiotic Lactic Acid Bacteria Viability in Potato Chips and Its Impact on Oil Oxidation

To produce a new probiotic-containing food product, potato chips, as the most preferred fast food, were chosen. Preferably, it should be preserved for a long period without oxidation. The presented study aimed to compare potato chips containing two lyophilized probiotic lactic acid bacteria (Bifidobacterium longum ATCC 15708 and Lactobacillus helveticus LH-B02) in order to retard lipid oxidation. Lyophilization of probiotics was carried out into two cryoprotective media-skim milk (SM) and gelatin/glycerol (GG) as lactose-free medium. Results revealed that GG and SM media were the most suitable for lyophilization of B. longum and L. helveticus, respectively. . The lyophilized live cells were incorporated in potato chips, packed and their effect on oil oxidation was assessed. . Results showed that the lyophilized B. longum in SM remained alive at 6.5 log CFU/g for 4 months at 30 °C. Interestingly, potato chip bags containing B. longum lyophilized in SM medium exhibited a decrease in peroxide value (PV) and acid value (AV) of the extracted oil by 40.13% and 25%, respectively, compared to the control bags. The created probiotic potato chips containing B. longum fulfill the criteria of the probiotic product besides the prime quality and sensory attributes.