Viability of Lactobacillus Rhamnosus R0011 in an Apple-Based Fruit Juice under Simulated Storage Conditions at the Consumer Level

Viability and In Vitro Gastrointestinal Transit Tolerance of Multispecies Probiotic Combinations Incorporated into Orange Juice and Drinking Water

Little is known about how combining probiotics affects the storage survival and functional performance of individual probiotics when incorporated into non-dairy drinks. Viability of Lacticaseibacillus rhamnosus GG (LG), Limosilactobacillus reuteri ATCC 55730 (LR), Bifidobacterium animalis subsp. lactis BB-12 (Bb), and Propionibacterium jensenii 702 (PJ), either alone or in multi-species combinations included in orange juice (OJ), were assessed during storage in refrigerated conditions and compared with bottled water (BW). The tolerance of probiotics included in refrigerated OJ to simulated gastrointestinal conditions was also examined. LG and LR viabilities were significantly higher in OJ than in BW (p ≤ 0.001), while the reverse was evident for PJ. Bb maintained high viability in both drinks. LG-PJ in both drinks and Bb-PJ in BW resulted in greater viabilities among the paired combinations compared to their respective monocultures when incorporated separately (p ≤ 0.001). The viability of LG in the LG-Bb-PJ combination improved significantly in BW compared with LG alone (p ≤ 0.001). OJ did not alter bacterial tolerance to simulated gastric juice but diminished tolerance to simulated intestinal juice (SIJ). In all combinations, tolerance of LG and LR to SIJ was improved, whereas tolerance of PJ declined significantly compared with respective monocultures (p ≤ 0.001). In conclusion, probiotic storage stability and gastrointestinal transit tolerance were species-dependent and affected by carrier type and combinations. These effects should be considered when formulating probiotic products.

Lacticaseibacillus rhamnosus: A Suitable Candidate for the Construction of Novel Bioengineered Probiotic Strains for Targeted Pathogen Control

Probiotics, with their associated beneficial effects, have gained popularity for the control of foodborne pathogens. Various sources are explored with the intent to isolate novel robust probiotic strains with a broad range of health benefits due to, among other mechanisms, the production of an array of antimicrobial compounds. One of the shortcomings of these wild-type probiotics is their non-specificity. A pursuit to circumvent this limitation led to the advent of the field of pathobiotechnology. In this discipline, specific pathogen gene(s) are cloned and expressed into a given probiotic to yield a novel pathogen-specific strain. The resultant recombinant probiotic strain will exhibit enhanced species-specific inhibition of the pathogen and its associated infection. Such probiotics are also used as vehicles to deliver therapeutic agents. As fascinating as this approach is, coupled with the availability of numerous probiotics, it brings a challenge with regard to deciding which of the probiotics to use. Nonetheless, it is indisputable that an ideal candidate must fulfil the probiotic selection criteria. This review aims to show how Lacticaseibacillus rhamnosus, a clinically best-studied probiotic, presents as such a candidate. The objective is to spark researchers’ interest to conduct further probiotic-engineering studies using L. rhamnosus, with prospects for the successful development of novel probiotic strains with enhanced beneficial attributes.

Coating Lacticaseibacillus rhamnosus GG in Alginate Systems: an Emerging Strategy Towards Improved Viability in Orange Juice

Fruit juices are successfully proposed as suitable probiotic vehicles, but researchers' efforts should be developed to avoid effects of bacteria overgrowing on sensory and nutritional cues of final products and to preserve viability of probiotic bacteria during storage. In the present study, encapsulation of Lacticaseibacillus rhamnosus GG strain in alginate systems was performed through ionotropic gelation technology. The alginate systems were optimized by using Box-Behnken Design to investigate the influence of three independent variables at three different levels: particle mean size and polydispersity index. The optimized probiotic-loaded alginate particles were added to orange juice samples. The viability of the probiotic strain, both as free and microencapsulated, was evaluated in orange juice stored at 5°C for 35 days. Morphology and size of probiotic-loaded alginate particles were found suitable for incorporation into juice. TEM analysis revealed that unloaded systems were clustered as nanoparticles (CL_NP), while the loaded sample appeared as a coated system (Coated_LGG). Microbiological evaluation revealed that the encapsulation assured the survival of Coated_LGG, with a reduction of less than 1-unit log in cellular density after 35 days of refrigerated storage in orange juice. Results indicated that the encapsulated bacteria did not affect the macroscopic properties neither the microbiological characteristic of orange juice; thus, it can be proposed as functional food.

Quality enhancement of Dendrobium officinale and banana juice through probiotic fermentation using beneficial lactic acid-producing bacteria

Consumption of functional juice is becoming increasingly popular. This study aimed to evaluate the effect of probiotic fermentation with Bacillus sp. DU-106; Lactobacillus planturum Lp-43 and Lactobacillus rhamnosus Lr-156 on the biochemical and functional characteristics, antioxidant activities and storage stability of Dendrobium officinale and banana (DOB) juice. The cell levels of the lactic acid bacteria reached near 9 log copies/mL after fermentation at 32 °C for 36 h and could keep in this level after storage at 4 °C for 28 days. After fermentation, total acidity, flavonoids and polysaccharide contents of DOB juice increased, while pH, dissolved oxygen, nitrite, nitrate, vitamin C, β-carotene, sugar contents and antioxidant capacity slightly decreased. Compared with nonfermented DOB juice, polyphenol oxidase (PPO) and peroxidase (POD) activities of fermented DOB decreased significantly, but the color value and the content of total phenols and vitamin C decreased slightly in fermented DOB juice during storage. Overall, the probiotic fermentation with selected strains could improve the quality the DOB juice, enhance antioxidant capacity and storage stability, and destroy accumulation of nitrite and nitrate during storage. Findings of this study would help in the development of beneficial beverages in industrial production.

Probiotics in Food Systems: Significance and Emerging Strategies Towards Improved Viability and Delivery of Enhanced Beneficial Value

Preserving the efficacy of probiotic bacteria exhibits paramount challenges that need to be addressed during the development of functional food products. Several factors have been claimed to be responsible for reducing the viability of probiotics including matrix acidity, level of oxygen in products, presence of other lactic acid bacteria, and sensitivity to metabolites produced by other competing bacteria. Several approaches are undertaken to improve and sustain microbial cell viability, like strain selection, immobilization technologies, synbiotics development etc. Among them, cell immobilization in various carriers, including composite carrier matrix systems has recently attracted interest targeting to protect probiotics from different types of environmental stress (e.g., pH and heat treatments). Likewise, to successfully deliver the probiotics in the large intestine, cells must survive food processing and storage, and withstand the stress conditions encountered in the upper gastrointestinal tract. Hence, the appropriate selection of probiotics and their effective delivery remains a technological challenge with special focus on sustaining the viability of the probiotic culture in the formulated product. Development of synbiotic combinations exhibits another approach of functional food to stimulate the growth of probiotics. The aim of the current review is to summarize the strategies and the novel techniques adopted to enhance the viability of probiotics.

Assessment of Probiotic Viability during Cheddar Cheese Manufacture and Ripening Using Propidium Monoazide-PCR Quantification

The use of a suitable food carrier such as cheese could significantly enhance probiotic viability during storage. The main goal of this study was to assess viability of commercial probiotic strains during Cheddar cheesemaking and ripening (4–6 months) by comparing the efficiency of microbiological and molecular approaches. Molecular methods such as quantitative PCR (qPCR) allow bacterial quantification, and DNA-blocking molecules such as propidium monoazide (PMA) select only the living cells’ DNA. Cheese samples were manufactured with a lactococci starter and with one of three probiotic strains (Bifidobacterium animalis subsp. lactis BB-12, Lactobacillus rhamnosus RO011, or Lactobacillus helveticus RO052) or a mixed culture containing B. animalis subsp. lactis BB-12 and L. helveticus RO052 (MC1), both lactobacilli strains (MC2), or all three strains (MC3). DNA extractions were then carried out on PMA-treated and non-treated cell pellets in order to assess PMA treatment efficiency, followed by quantification using the 16S rRNA gene, the elongation factor Tu gene (tuf) or the transaldolase gene (tal). Results with intact/dead ratios of bacteria showed that PMA-treated cheese samples had a significantly lower bacterial count than non-treated DNA samples (P < 0.005), confirming that PMA did eliminate dead bacteria from PCR quantification. For both quantification methods, the addition of probiotic strains seemed to accelerate the loss of lactococci viability in comparison to control cheese samples, especially when L. helveticus RO052 was added. Viability of all three probiotic strains was also significantly reduced in mixed culture cheese samples (P < 0.0001), B. animalis subsp. lactis BB-12 being the most sensitive to the presence of other strains. However, all probiotic strains did retain their viability (log 9 cfu/g of cheese) throughout ripening. This study was successful in monitoring living probiotic species in Cheddar cheese samples through PMA-qPCR.

Chitosan coated alginate beads for the survival of microencapsulated Lactobacillus plantarum in pomegranate juice

This work studied the effect of multi-layer coating of alginate beads on the survival of encapsulated Lactobacillus plantarum in simulated gastric solution and during storage in pomegranate juice at 4°C. Uncoated, single and double chitosan coated beads were examined. The survival of the cells in simulated gastric solution (pH 1.5) was improved in the case of the chitosan coated beads by 0.5-2 logs compared to the uncoated beads. The cell concentration in pomegranate juice after six weeks of storage was higher than 5.5logCFU/mL for single and double coated beads, whereas for free cells and uncoated beads the cells died after 4 weeks of storage. In simulated gastric solution, the size of the beads decreased and their hardness increased with time; however, the opposite trend was observed for pomegranate juice, indicating that there is no correlation between cell survival and the hardness of the beads.

Evaluation of yogurt and various beverages as carriers of lactic acid bacteria producing 2-branched (1,3)-β-D-glucan

Probiotic cultures are increasingly being incorporated into a wide variety of food products. Although lactobacilli and bifidobacteria are the most frequently used, other lactic acid bacteria (LAB) have been reported to be potential probiotics. Of these, the cider isolates Pediococccus parvulus (strains 2.6 and CUPV22) and Lactobacillus suebicus CUPV221 produce a 2-branched (1,3)-β-d-glucan exopolysaccharide that decreases serum cholesterol levels and affects the activation of human macrophages. For this reason, these 3 strains were incorporated into yogurt, orange juice, and 2 juice-milk beverages to evaluate the effect of the food matrix on the resistance of these strains to simulated gastrointestinal tract conditions. Our results showed that incorporation of the LAB did not significantly affect the physical and rheological properties of the food matrices tested. When incorporated in yogurt, LAB strains population decreased by 2 to 3 log orders of magnitude during the shelf life of the product (28 d). However, no significant decrease was observed in the juice and juice-milk beverages during the same storage period, except for Lb. suebicus, whose viability decreased by 3 log orders of magnitude. When strains were subjected to gastrointestinal tract conditions, a decrease in the survival was observed at the lower pH (1.8). However, incorporation of these LAB strains into orange juice increases their resistance to lower pH conditions, thus improving survival to gastrointestinal stress. Moreover, a protective effect was observed for P. parvulus CUPV22 and 2.6 to gastric stress in juice-milk beverages and to gastrointestinal stress in yogurt. Lactobacillus suebicus CUPV221 did not survive when incorporated into yogurt and juice-milk beverage.

Functional microorganisms for functional food quality

Functional microorganisms and health benefits represent a binomial with great potential for fermented functional foods. The health benefits of fermented functional foods are expressed either directly through the interactions of ingested live microorganisms with the host (probiotic effect) or indirectly as the result of the ingestion of microbial metabolites synthesized during fermentation (biogenic effect). Since the importance of high viability for probiotic effect, two major options are currently pursued for improving it--to enhance bacterial stress response and to use alternative products for incorporating probiotics (e.g., ice cream, cheeses, cereals, fruit juices, vegetables, and soy beans). Further, it seems that quorum sensing signal molecules released by probiotics may interact with human epithelial cells from intestine thus modulating several physiological functions. Under optimal processing conditions, functional microorganisms contribute to food functionality through their enzyme portfolio and the release of metabolites. Overproduction of free amino acids and vitamins are two classical examples. Besides, bioactive compounds (e.g., peptides, γ-amino butyric acid, and conjugated linoleic acid) may be released during food processing above the physiological threshold and they may exert various in vivo health benefits. Functional microorganisms are even more used in novel strategies for decreasing phenomenon of food intolerance (e.g., gluten intolerance) and allergy. By a critical approach, this review will aim at showing the potential of functional microorganisms for the quality of functional foods.