Effect of sub-lethal heat stress on viability of Lacticaseibacillus casei N in spray-dried powders

Protective Effect of Whey Protein and Polysaccharide Complexes on Lactobacillus paracasei F50: Comparative Analysis of Powder Characteristics and Stability

To enhance Lactobacillus paracei F50 viability during spray drying and long-term storage, this study evaluates whey protein (WP) crosslinked with four polysaccharides (κ-carrageenan (KC), xanthan gum (XG), low-methoxyl pectin (LMP), sodium alginate (SA)) for the first time as protective matrices for L. paracasei F50 during spray drying. The four kinds of crosslinked wall materials were compared by various characterization methods. Among them, the WP-κ-carrageenan (WP-KC) composite exhibited optimal performance, forming a uniform microcapsule with high colloidal stability. After spray drying, WP-KC achieved the highest viable cell density (9.62 lg CFU/g) and survival rate (91.85%). Notably, WP-KC maintained viability above 8.68 lg CFU/g after 120 days of storage at 4 °C, surpassing other formulations. Structural analysis showed that the WP-KC microcapsule was completely encapsulated without breaking or leaking and confirmed the molecular interaction between WP and KC. Under the condition of high temperatures (≤142.63 °C), the wall material of the microcapsule does not undergo any endothermic or exothermic process and is in a state of thermodynamic equilibrium, with excellent stability and good dispersion. Additionally, microcapsules exhibited enhanced resistance to thermal stress (55-75 °C) and UV irradiation, higher than that of free cells. These results highlight WP-KC as an industrially viable encapsulation system for improving probiotic stability in functional foods, offering critical insights into polysaccharide-protein interactions for optimized delivery systems.

Can operational parameters impact spray-dried bacteria viability and production costs? An experimental study with autochthonous Lactococcus lactis subsp. lactis isolated from Amazonian artisanal cheese

Lactococcus lactis subsp. lactis Q1C2, previously isolated from artisanal cheese produced in the Brazilian Amazon region, was subjected to spray drying protocols to evaluate the impact of operational parameters on cell viability, storage stability, and production costs. Concentrated reconstituted milk was used as the drying medium, and combinations of cell concentrate flow rates (Fcell,inj) and inlet air temperatures (T°Cair,in) were tested, resulting in 12 different treatments (T1-T12). After drying (day-0), higher survival rates were obtained with lower T°Cair,in (115 °C and 130 °C), while greater viability loss was associated with higher T°Cair,in and outlet air temperatures (T°Cair,out). Moisture content and water activity (aw) were inversely correlated with cell viability, with lower values resulting in greater losses. Cell viability was evaluated during the storage at 4 °C and 25 °C on days 15, 30, and 120. Viability was more stable at 4 °C, although significant reductions were observed for some treatments (P < 0.0001). At 25 °C, all treatments exhibited significant viability losses after 120 days (P < 0.0001). Among the treatments, T6 (Fcell,inj = 0.66 kg h-1 and T°Cair,in = 130 °C) showed the best balance between high cell viability and storage temperature, 10.00 ± 0.12 log cfu g-1 and 9.93 ± 0.13 log cfu g-1 after 120 days at 4 °C and 25 °C, respectively. In terms of production costs, T6 demonstrated advantages by minimizing energy consumption and mass loss during drying. Higher Fcell,inj reduced energy costs (P < 0.0001), while elevated T°Cair,in significantly increased energy costs (P < 0.0001). T6 optimized energy efficiency and achieved a favorable balance between viability and operational costs, highlighting its potential for industrial application. These findings demonstrate the viability of spray drying for producing dairy starter cultures, offering a cost-effective solution to preserve active starter cultures without the need for refrigeration.

Effect of microencapsulation on physical properties of powder developed from blended oils rich in PUFA

Microencapsulation of oil samples such as flaxseed oil, blended oils such as flaxseed-sesame oil and flaxseed-rice bran oil rich in omega-3 and omega-6 fatty acids was carried out through spray drying technique. During this study, emulsions were prepared and homogenized at 1000 rpm to prepare the stable emulsion. About 8% (w/w) of oils were encapsulated with maltodextrin as wall material and Tween 20 as an emulsifier, yielding a polyunsaturated fatty acid (PUFA) microencapsulated oil powder. The physical properties of powders were calculated based on the bulk density and tapped density observations. Apart from these, Carr's index (C) and Hausner's ratio evaluated to study the flow properties of microencapsulated powders ranged between 30 and 39 for Carr's index and 1.40-1.64 for Hausner ratio, respectively. The results of moisture content stated that oil-encapsulated powders exhibited higher shelf life due to lower moisture content values of 2-4%. Encapsulation efficiency of 73%, 60%, and 80% was achieved for flaxseed oil powder, flaxseed-sesame oil powder, and flaxseed-rice bran oil powder, respectively. Powders high in PUFA such as omega-3 and omega-6 are beneficial for addressing variety of health issues, that can be used most convenient way to receive important nutrients in our period of health issues.

Effect of gastrointestinal resistant encapsulate matrix on spray dried microencapsulated Lacticaseibacillus rhamnosus GG powder and its characterization

This study investigated spray drying a method for microencapsulating Lacticaseibacillus rhamnosus GG using a gastrointestinal resistant composite matrix. An encapsulate composite matrix comprising green banana flour (GBF) blended with maltodextrin (MD) and gum arabic (GA). The morphology of resulted microcapsules revealed a near-spherical shape with slight dents and no surface cracks. Encapsulation efficiency and product yield varied significantly among the spray-dried microencapsulated probiotic powder samples (SMPPs). The formulation with the highest GBF concentration (FIV) exhibited maximum post-drying L. rhamnosus GG viability (12.57 ± 0.03 CFU/g) and best survivability during simulated gastrointestinal digestion (9.37 ± 0.05 CFU/g). Additionally, glass transition temperature (Tg) analysis indicated good thermal stability of SMPPs (69.3 - 92.9 ℃), while Fourier Transform infrared (FTIR) spectroscopy confirmed the structural integrity of functional groups within microcapsules. The SMPPs characterization also revealed significant variation in moisture content, water activity, viscosity, and particle size. Moreover, SMPPs exhibited differences in total phenolic and flavonoid, along with antioxidant activity and color values throughout the study. These results suggested that increasing GBF concentration within the encapsulating matrix, while reducing the amount of other composite materials, may offer enhanced protection to L. rhamnosus GG during simulated gastrointestinal conditions, likely due to the gastrointestinal resistance properties of GBF.

Encapsulation of Lactiplantibacillus plantarum CRD7 in sub-micron pullulan fibres by spray drying: Maximizing viability with prebiotic and thermal protectants

Pullulan was used as the wall material for microencapsulation of L. plantarum CRD7 by spray drying, while isomalto-oligosaccharides (IMO) was used as prebiotic. Also, the effect of different thermal protectants on survival rate during microencapsulation was evaluated. Taguchi orthogonal array design showed that pullulan at 14 % concentration, IMO at 30 % concentration and whey protein isolate at 20 % rate were the optimized wall material, prebiotic and thermal protectant, respectively for microencapsulation of L. plantarum. FESEM images revealed that the spray-dried encapsulates were fibrous similar to those produce by electrospinning, while fluorescence microscopy ascertained that most of the probiotic cells were alive and intact after microencapsulation. The adsorption-desorption isotherm was of Type II and the encapsulate had specific surface area of 1.92 m2/g and mean pore diameter of 15.12 nm. The typical amide II and III bands of the bacterial proteins were absent in the FTIR spectra, suggestive of adequate encapsulation. DSC thermogram showed shifting of melting peaks to wider temperature range due to interactions between the probiotic and wall materials. IMO at 30 % (w/w) along with WPI at 20 % concentration provided the highest storage stability and the lowest rate of cell death of L. plantarum after microencapsulation. Acid and bile salt tolerance results confirmed that microencapsulated L. plantarum could sustain the harsh GI conditions with >7.5 log CFU/g viability. After microencapsulation, L. plantarum also possessed the ability to ferment milk into curd with pH of 4.62.

Effect of prebiotics on thermally acclimatized lactobacilli cultures and their application as synbiotics in RTD fruit drinks

In this study, the effect of prebiotics such as fructooligosaccharides (FOS), galactooligosaccharides (GOS), isomaltooligosaccharides (IMO), and inulin on the probiotic biomass and its probiotic properties were studied for thermally acclimatized Lactobacillus helveticus (H-45) and Lacticaseibacillus casei N (N-45) strains at 45 ℃ using adaptive laboratory evolution method. Among the prebiotics studied, GOS was found to be more suitable for synbiotic preparation. The tolerance of lactobacilli cultures H-45 and N-45 in the presence of acid and bile were 4.79 and 8.60% and 2.84 and 4.65% higher than their wild-type strains (H-37 and N-37). Similarly, H-45 and N-45 showed an increase in survivability of 5.29 and 8.63% under simulated gastric conditions and 9.21 and 7.70% under simulated intestinal conditions than H-37 and N-37. Propionic acid yield increased by 0.65-fold in N-45 compared to N-37 in the presence of GOS as a prebiotic, whereas H-37 showed 0.26-fold higher propionic acid production than H-45. Thermally acclimatized strain N-45 showed better survivability under stress conditions than H-45. The synbiotic combination of N45 + GOS was spray-dried using corn starch (CS) as carrier material to obtain spray-dried synbiotic powder (N45 + CS + GOS). This synbiotic powder was added to the ready-to-drink (RTD) fruit drinks prepared from five fruit-flavoured squashes (pineapple, orange, grape, mango, and lemon ginger). The varied amounts of added synbiotic powder did not significantly alter the physicochemical properties of the fruit drinks. Hence, synbiotic formulation N45 + GOS + CS may find application in developing various functional foods.

The Effects of Cellular Membrane Damage on the Long-Term Storage and Adhesion of Probiotic Bacteria in Caco-2 Cell Line

Adhesion is one of the main factors responsible for the probiotic properties of bacteria in the human gut. Membrane proteins affected by cellular damage are one of the key aspects determining adhesion. Fluid-bed-dried preparations containing probiotic bacteria were analyzed in terms of their stability (temperature of glass transition) and shelf life in different conditions (modified atmosphere, refrigeration). Imaging flow cytometry was utilized to determine four subpopulations of cells based on their physiological and morphological properties. Lastly, adhesion was measured in bacteria cultured in optimal conditions and treated with heat shock. The results show that the subpopulations with no or low levels of cell membrane damage exhibit the ability to adhere to Caco-2 cells. The temperature of protein denaturation in bacteria was recorded as being between 65 °C and 70 °C. The highest glass transition temperature (Tg) value for hydroxypropyl methylcellulose (used as a coating substance) was measured at 152.6 °C. Drying and coating can be utilized as a sufficient treatment, allowing a long shelf-life (up to 12 months). It is, however, worth noting that technological processing, especially with high temperatures, may decrease the probiotic value of the preparation by damaging the bacterial cells.

Understanding the Probiotic Bacterial Responses Against Various Stresses in Food Matrix and Gastrointestinal Tract: A Review

Probiotic bacteria are known to have ability to tolerate inhospitable conditions experienced during food preparation, food storage, and gastrointestinal tract of consumer. As probiotics are living cells, they are adversely affected by the harsh environment of the carrier matrix as well as low pH, bile salts, oxidative stress, osmotic pressure, and commensal microflora of the host. To overcome the unfavorable environments, many probiotics switch on the cell-mediated protection mechanisms, which helps them to survive, acclimatize and remain operational in the harsh circumstances. In this review, we provide comprehensive understanding on the different stresses experienced by the probiotic when added in carrier food as well as during human gastrointestinal tract transit. Under such situation how these health beneficial bacteria protect themselves by activation of several defense systems and get adapted to the lethal environments.

Exploring the roles of starch for microbial encapsulation through a systematic mapping review

Microorganism encapsulation protects them from stressful conditions and assists in maintaining their viability, being especially beneficial when the carrier material is a renewable and biodegradable biopolymer, such as starch. Here, a systematic mapping was performed to provide a current overview on the use of starch-based systems for microbial encapsulation. Following well-established guidelines, a systematic mapping was conducted and the following could be drawn: 1) there was a significant increase in publications on microbial encapsulation using starch over the past decade, showing interest from the scientific community, 2) ionotropic gelation, emulsification and spray drying are the most commonly used techniques for starch-based microbial encapsulation, and 3) starch play important functions in the encapsulation matrix such as assisting in the survival of the microorganisms. The information gathered in this systematic mapping can be useful to guide researchers and industrial sectors on the development of innovative starch-based systems for microbial encapsulation.

Increased heat tolerance and transcriptome analysis of Salmonella enterica Enteritidis PT 30 heat-shocked at 42 ℃

In this study, we compared the heat tolerance parameter (D_65℃) values of Salmonella enterica serovar Enteritidis PT 30 (S. Enteritidis ) heat adapted at different degrees (at 42 ℃ for 20-180 min) and cultivated using two methods. The treated group with the highest D_65℃ value (LP-42 ℃-60 min) and the untreated groups (Control-TSB and Control-TSA) were subjected to transcriptome analysis. Heat-adaptation increased the D_65℃ values of S. Enteritidis by 24.5-60.8%. The D_65℃ values of the LP-42 ℃-60 min group (1.85 ± 0.13 min, 7.7% higher) was comparable to that of the Control-TSA. A total of 483 up- and 443 downregulated genes of S. enteritidis were identified in the LP-42 ℃-60 min group (log₂fold change > 1, adjusted p-value < 0.05). Among these genes, 5 co-expressed and 15 differentially expressed genes in the LP-42 ℃-60 min and Control-TSA grops possibly contributed to the high D_65℃ values of S. Enteritidis . The Rpo regulon was involved in the heat adaptation of S. Enteritidis , as evidenced by the significant upregulation of rpoS, rpoN, and rpoE. KEGG enrichment pathways, such as biosynthesis of secondary metabolites, tricarboxylic acid, and ribosomes were identified and mapped to reveal the molecular mechanisms of S. enteritidis during heat adaptation. This study quantified the enhanced heat tolerance of S. Enteritidis heat adapted at different degrees of heat-adaptation. The results of this study may serve as a basis for elucidating the molecular mechanisms underlying the enhanced heat tolerance at the transcriptome level.

Journey of the Probiotic Bacteria: Survival of the Fittest

This review aims to bring a more general view of the technological and biological challenges regarding production and use of probiotic bacteria in promoting human health. After a brief description of the current concepts, the challenges for the production at an industrial level are presented from the physiology of the central metabolism to the ability to face the main forms of stress in the industrial process. Once produced, these cells are processed to be commercialized in suspension or dried forms or added to food matrices. At this stage, the maintenance of cell viability and vitality is of paramount for the quality of the product. Powder products requires the development of strategies that ensure the integrity of components and cellular functions that allow complete recovery of cells at the time of consumption. Finally, once consumed, probiotic cells must face a very powerful set of physicochemical mechanisms within the body, which include enzymes, antibacterial molecules and sudden changes in pH. Understanding the action of these agents and the induction of cellular tolerance mechanisms is fundamental for the selection of increasingly efficient strains in order to survive from production to colonization of the intestinal tract and to promote the desired health benefits.

Novel nano-encapsulated probiotic agents: Encapsulate materials, delivery, and encapsulation systems

Gut microbes are closely associated with most human health. When ingested orally, probiotics can effectively regulate the composition and quantity of human intestinal microorganisms, which is beneficial to human health. However, probiotics will be affected by the harsh environment of the digestive tract during the in vivo transportation process, and ensuring the viability of probiotics is a great challenge. Probiotic encapsulating technology provides an effective solution to this problem. The introduction of extreme temperatures, large probiotic microcapsule sizes and the difficulty in controlling probiotic microcapsule particle sizes mean that traditional microcapsule encapsulation methods have some limitations. From traditional microcapsule technology to the bulk encapsulation of probiotics with nanofibers and nanoparticles to the recent ability to wear nano "armor" for a single probiotic through biofilm, biological membrane and nanocoating. Emerging probiotic nanoagents provides a new conceptual and development direction for the field of probiotic encapsulation. In this review, we presented the characteristics of encapsulated probiotic carrier materials and digestive tract transport systems, we focused on the encapsulation systems of probiotic nanoagents, we analyzed the shortcomings and advantages of the current agent encapsulation systems, and we stated the developmental direction and challenges for these agents for the future.