Simulated Gastrointestinal Conditions Research Articles

In Vitro Cholesterol Uptake by the Microflora of Selected Kefir Starter Cultures

Kefir, a fermented milk beverage, is recognized for its potential health benefits, including its cholesterol-lowering properties. This study demonstrated that selected kefir starter cultures, including Lactococcus strains and yeasts, significantly reduce cholesterol-binding capacity under simulated gastrointestinal conditions, underscoring the challenges of probiotic delivery. We compared the performance of these cultures under laboratory conditions (growth broths) and simulated digestive juice models. Lactococcus strains showed significant differences in cholesterol binding between the two environments, highlighting the limitations of relying solely on laboratory testing. Yeast cultures also exhibited greater cholesterol binding in their native broths, but their survival was limited in digestive models. Our findings suggest that effective probiotic formulations should prioritize strains with high cholesterol-binding capacity and robust survival rates throughout the digestive tract. This study provides valuable insights for future research on the mechanisms behind these functionalities and the potential of kefir yeast strains for use in human digestive models. Our results can be used to inform the development of improved probiotic formulations for cholesterol management.

Targeted Screening of Lactiplantibacillus plantarum Strains Isolated from Tomatoes and Its Application in Tomato Fermented Juice

This study explores the functional attributes of Lactiplantibacillus plantarum (L. plantarum) strains isolated from fermented tomato juice, focusing on their physiological, biochemical, and probiotic characteristics. The identified 66 gram-positive strains included 36 L. plantarum ones, which exhibited robust growth in acidic environments (pH 2.0–5.0) and utilization of various carbohydrates. Notably, seven strains outperformed a commercial strain in extreme acidic conditions. Antioxidant activity varied, with strain A24 showing the highest hydroxyl radical scavenging ability, while strains with high surface hydrophobicity had lower DPPH scavenging activity, indicating no direct correlation between these properties. Strains also showed strain-specific differences in carbohydrate utilization and antibiotic resistance, with some resistant to gentamicin and ciprofloxacin. Survival rates under simulated gastrointestinal conditions were strain-specific, with some strains demonstrating high survival rates, indicating their potential as probiotics. Furthermore, 13 strains used as fermentation starters in tomato juice significantly enhanced antioxidant activity and reduced pH and total soluble solids, indicating efficient sugar utilization and lactic acid production. These findings suggest that L. plantarum strains are well-suited for functional food fermentation and probiotic applications, with strain-specific traits offering versatility for use in acidic food products and probiotic formulations.

Comprehensive genomic analysis and evaluation of in vivo and in vitro safety of Heyndrickxia coagulans BC99

This study aimed to evaluate the safety profile and beneficial effects of Heyndrickxia coagulans strain BC99 (BC99) for potential use in functional foods and pharmaceuticals. We began with whole genome sequencing of BC99, followed by a comprehensive safety assessment comprising genome analysis, hemolysis, cytotoxicity, antibiotic susceptibility tests, and cell adhesion and tolerance studies, along with acute and subacute oral toxicity studies in animal models. BC99 was isolated from a well-characterized collection originating from the feces of a healthy infant. Our results indicated no hemolytic activity on Columbia blood agar plates and broad antibiotic sensitivity, including to gentamicin, ampicillin, chloramphenicol, ciprofloxacin, and others. Cytotoxicity testing confirmed no adverse effects on HT-29 cells and significant adhesive properties to intestinal epithelial cells. Tolerance tests demonstrated over 90% viability of BC99 under simulated gastrointestinal conditions. In vivo studies in mice and rats confirmed the absence of adverse effects following oral administration. Collectively, these findings support BC99’s robust tolerance to gastrointestinal environments, strong adhesion capabilities, and a broad spectrum of antibiotic resistance, underlining its potential as a safe and effective agent for gut microbiota modulation and host health enhancement.

Stability and release kinetics of nanoliposomes containing bitter melon fruit extract at different temperatures and pH values, and in simulated gastrointestinal conditions

In this study, the nanoliposomes loaded with bitter melon extract were synthesized at different concentrations of lecithin (1, 3, and 5 g/100 g) and extract (0.5 and 1 g/100 g). Thermal properties of nanoliposomes and their stability at various pH values and temperatures, as well as under simulated gastrointestinal conditions, were assessed. The results showed that an increase in the concentration of lecithin and extract elevated the melting temperature of the nanoliposomes. The release of the extract increased at high temperatures, and it was more pronounced at pH=3 than the other pH values. Also, the release followed a continuous and gradual trend under the simulated gastrointestinal conditions, slower in gastric conditions than in intestinal. Additionally, it was reduced at higher concentrations of lecithin and extract in simulated gastrointestinal conditions. The release kinetics of the extract followed different models based on temperature and pH. In conclusion, nanoliposomes were suitable and highly stable carriers for the bitter melon extract encapsulation. Moreover, the controlled release of the extract from the nanoliposomes could be properly evaluated in model systems and foodstuffs using empirical models.

Co-encapsulation of probiotic bacteria and fructooligosaccharides in basil seed gum-stabilized double emulsion gels: Probiotic viability and physicochemical properties

Double emulsions (DEs) present many potential applications for encapsulating and protecting probiotics. However, their high instability limit their real applications. To improve the prolonged stability of DEs, Lacticaseibacillus rhamnosus and Lactobacillus gasseri were separately co-encapsulated together in the presence of fructooligosaccharides (FOSs) and basil seed gum (BSG) within the internal (W1) and external (W2) aqueous phases of double emulsion gels (DEGs; W1-sol/O/W2-gel). Physical properties of DEGs, and viability of probiotics during heat processing, gastrointestinal digestion and storage were evaluated. Appropriate physical stability was observed during storage for 28 d at 4 ± 2 °C. The FOSs and microorganism type showed not effect on the droplet size (10.63 to 10.47 µm). Turbidimetry, physical stability, and morphological studies revealed the formation of aggregated droplets after 3 weeks. All DEGs presented high (>90 %) encapsulation efficiency. The viability of microencapsulated probiotics over time (14.89–14.08 %) and against simulated gastrointestinal conditions was higher than that of free cells. The encapsulation of bacteria in W1 in the presence of FOSs led to a significant improvement of viability against heat (only 1.35 % to 6.83 % reduction at 72 °C). L. gasseri showed a higher stability against environmental conditions. Finally, BSG-stabilized DEGs can be considered for increasing the viability of probiotic in functional foods.

Starch-based encapsulation to enhance probiotic viability in simulated digestion conditions

This research aims to meet the demand for efficient delivery systems in the food, nutraceutical, and pharmaceutical industries. The study involved the synthesis of starch-based nanoparticles for potential application in the encapsulation of Lactobacillus rhamnosus. Various techniques such as zeta sizer, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to characterize the encapsulated probiotics in microbeads. The results showed 85.00 % encapsulation efficiency of beads. Microscopic analysis revealed that the probiotics accumulated within the wall material and formed small, smooth polygonal granules on the capsule surface. XRD analysis confirmed the presence of amorphous humps and some crystallinity of nanoparticles in the capsules. Moreover, encapsulation significantly improved probiotic viability under simulated gastrointestinal conditions. This study highlights the potential of starch-based nanoparticles to enhance the stability and viability of probiotics, demonstrating their potential applications across various industrial sectors. Further research should focus on investigating the long-term stability and functional efficacy of encapsulated probiotics in microbeads for real-world applications.

Isolation and characterization of Bifidobacterium spp. From breast milk with different human milk oligosaccharides utilization and anti-inflammatory capacity

Breast milk is the best source of nutrition for infants. Human milk oligosaccharides (HMOs) and the corresponding HMOs-consuming Bifidobacterium positively influence infant health. This study aims to isolate and characterize Bifidobacterium from breast milk of healthy Chinese mothers, identifying the most efficacious strains for inclusion in simulated maternal milk formulas. Nine Bifidobacterium strains (two of B. breve and seven of B. infantis) were isolated, exhibiting a broad spectrum of probiotic potential. This included tolerance to simulated infant gastrointestinal conditions, notable adhesion, antibacterial, antioxidant activities, and HMOs utilization ability. Lacto-N-Tetraose (LNT) is preferred in early growth among Bifidobacterium isolates. B. breve showed a preference for LNT, whereas B. infantis showed a preference for fucosylated HMOs, and displayed reduced utilization of sialylated HMOs. They also exhibited robust safety profiles, including no hemolytic activity, an appropriate D/L lactate-producing ratio, and non-toxicity in an acute oral toxicity assay on mice. It is noteworthy that B. breve N-90, O-147, B. infantis O-161 and R-1 exhibited anti-inflammatory effects in LPS-induced RAW 264.7 cells. Specifically, a notable reduction in TNF-α levels was observed in pre-treatment, while a decrease in IL-1β and IL-6 levels in co-treatment. B. breve N-90 and B. infantis R-1 were identified finally as promising probiotic candidates. Their whole-genome sequencing analysis confirmed presence of functional genes associated with gastrointestinal colonization, antioxidation, and glycoside hydrolase activity on HMOs. The annotation for antibiotic resistance and virulence genes concurred with phenotypes, further validating the safety. Breast milk is a good source for Bifidobacteria isolation, while Bifidobacteria utilize HMOs in a strain-dependent manner. The two selected strains, B. breve N-90 and B. infantis R-1, are potential candidates for inclusion in simulated maternal milk formulas and deserved further in vivo investigation for their health-promoting effects.

Isolation and Characterization of a Bacteriophage with Potential for the Control of Multidrug-Resistant Salmonella Strains Encoding Virulence Factors Associated with the Promotion of Precancerous Lesions

Background: Antimicrobial-resistant bacteria represent a serious threat to public health. Among these bacteria, Salmonella is of high priority because of its morbidity levels and its ability to induce different types of cancer. Aim: This study aimed to identify Salmonella strains encoding genes linked to the promotion of precancerous lesions and to isolate a bacteriophage to evaluate its preclinical potential against these bacteria. Methodology: An epidemiological approach based on wastewater analysis was employed to isolate Salmonella strains and detect genes associated with the induction of precancerous lesions. Antimicrobial susceptibility was assessed by the disk diffusion method. A bacteriophage was isolated via the double agar technique, and its morphological characteristics, stability, host range, replication dynamics, and ability to control Salmonella under different conditions were evaluated. The bacteriophage genome was sequenced and analyzed using bioinformatics tools. Results: Thirty-seven Salmonella strains were isolated, seventeen of which contained the five genes associated with precancerous lesions’ induction. These strains exhibited resistance to multiple antimicrobials, including fluoroquinolones. A bacteriophage from the Autographiviridae family with lytic activity against 21 bacterial strains was isolated. This phage exhibited a 20 min replication cycle, releasing 52 ± 3 virions per infected cell. It demonstrated stability and efficacy in reducing the Salmonella concentration in simulated gastrointestinal conditions, and its genome lacked genes that represent a biosafety risk. Conclusion: This bacteriophage shows promising preclinical potential as a biotherapeutic agent against Salmonella.

In vitro validation of colon delivery of vitamin B2 through a food grade multi-unit particle system.

Colon target delivery of active ingredients is frequently applied in pharmaceutical products. However, in functional food and beverage applications, dietary supplements, and medical nutrition, formats targeting colonic delivery to improve human health are rare. Nevertheless, there is emerging evidence for beneficial effects of colonic delivered nutrients on gut microbiota and host health which increases the demand for sustainable food grade materials that are regulatory approved for application. In this paper, we describe a double layer coated multi-unit particle system (MUPS) with a diameter of approximately 730 microns consisting of food grade materials: shellac as outer layer, alginate as inner layer, cellulose as a core and riboflavin as active ingredient. The suitability of the MUPS for colonic delivery was tested in three well-established in vitro digestion and fermentation models: the USP Apparatus 3 and the TNO Intestinal Models 1 and 2 (TIM-1 and TIM-2). All systems confirmed the integrity of the MUPS under simulated upper gastrointestinal tract conditions with approximately 90% of the active ingredient being released under simulated ileal-colonic conditions. The TIM-2 model also showed the effects of riboflavin loaded MUPS on the microbiome composition with an increase in the production of short-chain fatty acids, acetate and butyrate. The results of these experiments provide a reliable basis for validation of this vitamin-loaded food grade MUPS in future human clinical trials. In addition, following the recent announcement of the European Commission to restrict intentionally added microplastics to products, the materials used in the described formulation offer an environmentally friendly alternative to often applied methyl acrylate based coatings.

Encapsulation of Lacticaseibacillus rhamnosus by Extrusion Method to Access the Viability in Saffron Milk Dessert and Under Simulated Gastrointestinal Conditions

ABSTRACTThe effectiveness of probiotics in delivering health benefits may be associated with their capacity to maintain a minimum concentration of 106 CFU/g during food storage and to successfully colonize the gastrointestinal tract (GI). Lacticaseibacillus rhamnosus (LR) is a probiotic that does not exhibit adequate stability under harsh conditions. To enhance the survival capacity of LR during gastrointestinal storage, alginate (ALG) was used as a primary encapsulating layer through extrusion microencapsulation. Subsequently, camelina seed mucilage (CSM) and camelina seed protein (CSP) were applied as secondary layers at varying concentrations (0%–4%). Among the tested formulations, ALG‐CSM‐CSP (1.5%, 4%, 4% w/w) exhibited significantly higher encapsulation efficiency (94.15%) and provided appropriate LR encapsulation in SEM image. Three saffron milk desserts (SMD) containing free LR (FLR), microencapsulated LR (MLR), and a control (C) were prepared, followed by physicochemical and microbiological assessments of the samples. The result showed that at the end of storage, SMD had the lowest pH (6.21), the highest acidity (30°D), and maintained the permissible limit of probiotic bacteria (6.7 log cfu/mL) among the samples. In GI, the MLR and FLR survival rates were 43% and 45.4%, respectively on the 14th day of storage, respectively. The MLR hardness (313.70 g), adhesiveness (2.01 mJ), chewiness (9.36) and gumminess (58.8) had the greatest values among the samples. Moreover, SEM images showed a relatively denser structure for MLR. In conclusion, this study highlights the potential of CSM and CSP to protect probiotics, offering valuable insights for developing new functional foods with improved survival during storage and GI.

Sauerkraut‐derived LAB strains as potential probiotic candidates for modulating carbohydrate digestion attributing bacterial organic acid profiling to antidiabetic activity

AbstractSauerkraut‐derived lactic acid bacterial (LAB) strains have gained attention due to their potential health benefits. This study focuses on evaluating seven Sauerkraut‐derived RAMULAB strains isolated from sauerkraut, aiming to identify promising candidates for modulating α‐glucosidase (AG) and α‐amylase (AM) enzymatic functions. RAMULAB strains with remarkable probiotic potential can contribute to the digestive health and manage conditions like diabetes. Identifying robust candidates from sauerkraut, a fermented food, holds promise for natural and cost‐effective probiotic sources. The RAMULAB strains underwent extensive characterization, including identification through 16S ribosomal RNA (rRNA) sequencing. Their tolerance to harsh conditions, adherence properties, antimicrobial activity, antioxidant potential, and inhibition of AG and AM were assessed. In silico analyses explored their molecular interactions, particularly with hydroxycitric acid, a potential antidiabetic compound. Among the RAMULAB strains, RAMULAB48 emerged as a standout candidate. It displayed exceptional resilience to acidic bile (≥97%), and simulated gastrointestinal conditions (≥95%), highlighting its suitability for probiotic applications. RAMULAB48 exhibited robust adherence properties, including cell‐surface hydrophobicity (80%), autoaggregation (42%), coaggregation with pathogens (≥33%), and adhesion to epithelial cells. Additionally, all seven isolates demonstrated gamma‐hemolysis and resistance to antibiotics (Kanamycin, Methicillin, and Vancomycin), while displaying strong antibacterial properties against foodborne pathogens. These RAMULAB strains also exhibited varying degrees of antioxidant activity, with RAMULAB48 displaying the highest potential (≥41%). In terms of antidiabetic activity, cell‐free supernatant (CS) obtained from RAMULAB48 expressed the highest inhibition levels, notably inhibiting yeast AG by an impressive 59.55% and AM being by a remarkable 67.42%. RAMULAB48 produced organic acids, including hydroxycitric acid (28.024 mg/mL), which showed promising antidiabetic properties through in silico analyses, indicating favorable interactions with the target enzymes. This study identifies Lacticaseibacillus paracasei RAMULAB48, a Sauerkraut‐derived RAMULAB strain, as a promising probiotic candidate with exceptional tolerance, adherence properties, antimicrobial activity, antioxidant potential, and antidiabetic effects. The presence of hydroxycitric acid further underscores its potential in managing diabetes.

Genomic Characterization and Probiotic Properties of Lactiplantibacillus pentosus Isolated from Fermented Rice.

The aim of the study was the preliminary genetic and phenotypic characterization of a potential probiotic strain of Lactiplantibacillus pentosus (strain krglsrbmofpi2) obtained from traditionally fermented rice. Genome sequencing revealed that the strain has a 3.7-Mb genome with a GC content of 46 and a total of 3192 protein-coding sequences. Using bioinformatic methods, we have successfully identified phage genes, plasmids, pathogenicity, antibiotic resistance and a variety of bacteriocins. Through comprehensive biochemical and biophysical analyses, we have gained valuable insights into its auto-aggregation, co-aggregation, antibiotic resistance, hydrophobicity, antioxidant activity and tolerance to simulated gastrointestinal conditions. The safety evaluation of the isolated L. pentosus was performed on the basis of its haemolytic activity. Our studies have shown that this strain has a strong antagonistic activity against the priority pathogens identified by the World Health Organization such as Vibrio cholerae, Clostridium perfringens, Salmonella enterica subsp. enterica ser. Typhi, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus. It is essential to fully understand the genetic and functional properties of the L. pentosus strain before considering its use as a useful probiotic in the food industry.

Eco-friendly encapsulation: Investigating plant-based protein-alginate shells for efficient delivery and digestion of hemp seed oil encapsulated via supercritical CO2 dispersion

In this study, supercritical carbon dioxide solution-enhanced dispersion (SEDS) was used to encapsulate hemp seed oil (HSO) within matrices of hemp seed protein isolate (HPI), pea protein (PPI) and soy protein (SPI) (0.5 % w/v) in complex with alginate (AL) (0.01 % w/v). The effects of different pH levels (3–9), NaCl concentrations (0–200 mmol/L) and simulated gastrointestinal conditions on HSO release and digestion patterns were analyzed. The findings revealed that SPI/AL microcapsules effectively maintained structural integrity and controlled oil release across diverse pH levels and salt concentrations. During gastrointestinal phases, minimal oil release was observed during oral digestion (<25 % for all samples), while significant (P < 0.05) gastric release occurred in PPI/AL (55.4 %) and SPI/AL (78.1 %) microcapsules. Surprisingly, HPI/AL microcapsules exhibited delayed and sustained release (27.9 %), indicating their potential as ideal wall material for delivering sensitive food and pharmaceutical ingredients to the intestinal stage while minimizing damage in the harsh gastric environment.

Preparation, characterization, and stability of chitosan-tremella polysaccharide layer-by-layer encapsulated astaxanthin nanoemulsion delivery system

In this study, a layer-by-layer (LBL) encapsulated astaxanthin (Ast) nanoemulsion delivery system based on chitosan (CS) and tremella polysaccharide (TP) was successfully developed. The system constructed an Ast-CS-TP emulsion with high encapsulation efficiency and an excellent stability profile by utilizing the opposite charge properties of CS and TP. This study evaluated the effects of different stresses (including temperature, salt addition, pH, UV irradiation, and centrifugal force) on the emulsion's stability. To further investigate the protective mechanism of the emulsions, we performed antioxidant activity experiments after UV treatment. Additionally, an in vitro digestion experiment was conducted to assess the behavior of Ast emulsion under simulated gastrointestinal conditions. The stability correlation coefficients were calculated using the Python database Pandas. The results showed that Ast-CS-TP emulsions exhibited turbidity and enhanced homogeneity with a small particle size of around 400 nm and a high absolute zeta potential of 35 mV and exhibited excellent stability under various stresses. The Ast-CS-TP emulsions also exhibited pH-responsive release at pH ≥ 7, consistent with pH changes in the gastrointestinal tract, and were stable in highly concentrated salt solutions. We found that the CS and TP layers significantly improved the photostability of Ast. CS and TP significantly enhanced Ast's oral bioavailability. The stability correlation coeffcients showed that pH and salt concentration were the largest factors that affected the stability of the emulsion. This study provided important insights into the encapsulation and targeting of Ast, providing a theoretical foundation and technical guidance for the comprehensive utilization of Ast.

Development of vitamin D3 and Spirulina platensis protein hydrolysates co-loaded nanoliposomes and coated by sodium caseinate

The objective of this study was to investigate the co-loading of vitamin D3 (VitD3) and Spirulina platensis protein hydrolysates (SPH) within coated nanoliposomes (NLPs) by sodium caseinate, with the intention of developing a novel nutritional supplement. The coated NLPs exhibited particle size, PDI, and zeta potential values of 185.30 ± 29.62 nm, 0.22±0.04, and +18.70 ± 3.44 mV, respectively. Moreover, the encapsulation efficiencies of the coated NLPs for VitD3 and SPH were 83.24 ± 4.22 % and 89.41 ± 4.36 %, respectively. The improving effect of the surface coating by sodium caseinate on the stability and function of the NLPs was exhibited through analysis of chemical structure, thermal stability, and crystalline structure. The transmission electron microscopy pictures of the developed NLPs revealed a spherical morphology with a thin layer around the vesicle. The loaded VitD3 and SPH in the coated NLPs showed controlled release profiles during incubation in the simulated gastrointestinal condition. Moreover, the VitD3/SPH co-loaded NLPs and their coated form had no considerable cell toxicity. To conclude, the developed nanosystem demonstrated the suitable characteristics of a nanocarrier for reaping the nutritional benefits of VitD3 and SPH.

Isolation and evaluation of Pediococcus acidilactici YH-15 from cat milk: Potential probiotic effects and antimicrobial properties

The study aimed to screen for the possible presence of lactic acid bacteria (LAB) in cat milk in order to evaluate their probiotic properties. The isolates were characterized by biochemical identification, morphological tests and 16S rDNA sequencing. Afterward, gastrointestinal passage, in vitro safety and probiotic properties were evaluated. The results showed that the isolates had 10 strains of Pediococcus acidilactici permitted in the feed additive catalog. The high survival rate in the acid and bile salt resistance test reflected the good strain tolerance of the isolates to the simulated gastrointestinal conditions of the host in vitro. The mean inhibitory diameters of the 10 strains against chloramphenicol and tetracycline were 23.6 mm and 17.4 mm, respectively; none of the hemolytic tests showed α/β hemolytic ring. The bacteriostatic test showed that P. acidilactici YH-9, YH-14 and YH-15 had inhibitory effects on four common pathogenic bacteria, including Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Streptococcus. The adhesion test showed that P. acidilactici YH-15 had good adhesion to HT-29 cells. Based on these results, we concluded that P. acidilactici YH-15 extracted from cat milk has potential application as a clinical probiotic therapy and health care product.

Effects of adding autochthonous Lacticaseibacillus paracasei culture on the characteristics of Minas Frescal goat cheese and its survival under simulated gastrointestinal conditions

A freeze-dried lactic acid culture was prepared with an autochthonous strain of Lacticaseibacillus paracasei TRA061676 (Lp-TRA061676), cultivated in skimmed goat milk and its technological suitability in the production of Minas Frescal Goat Cheese (MFGC) was investigated. The viability of the freeze-dried culture was greater than 8.92 Log CFU g−1 during 360 days of storage at −22 °C. Lp-TRA061676 incorporated into MFGC showed remarkable survival, with populations of 9.65 Log CFU g−1 and a survival rate under in vitro gastrointestinal tract conditions of 96.90% for 28 days at 4 °C. Lp-TRA061676 did not modify the proximate composition of MFGC, but it affected the physicochemical characteristics and instrumental color, and improved the product's texture. These results demonstrate the suitability of Lp-TRA061676 for producing MFGC and the potential of this cheese to be used as an effective matrix to protect the strain from gastrointestinal conditions.

Probiotic Properties of Lactobacilluscasei and L. plantarum Isolated From Overripe Avocado Pear

Probiotics have been researched for their benefit to gut health. Research for sources of probiotic bacteria has moved from milk to plants, as they have been found to be an inexhaustible source of lactic acid bacteria (LAB). The probiotic properties of lactic acid bacteria isolated from Over ripe Avocado pear on selected bacterial species were assessed. Fifty Unripe Avocado pears were purchased from different markets and allowed to ferment. Enumeration of the microorganisms and pure culture isolation were done on MRS agar supplemented with1.0% CaCO3 at 37 oC for 48 hours; using the pour plate and streak plate methods respectively. The isolates were identified based on their microscopic, macroscopic, biochemical and molecular characteristics. They include Lactobacillus casei and L. plantarum. LAB isolates were tested for their phenol tolerance, bile salt tolerance, acid tolerance and antimicrobial activity. All the isolates were tolerant to simulated gastrointestinal conditions. Growth of the isolates was observed at different temperature between 15 oC to 60 oC. They exhibited tolerance to phenol ranging from 0.085±0.01% to 2.40±0.02%. Tolerance to bile salt ranged from 1.06x101± 0.96x101 to 3.04x103±1.15x102. The acid tolerance level of the LAB obtained ranged from 2.98x102±1.30x102 to 8.78x102±2.22x102. Agar-well diffusion method was used to determine the antimicrobial susceptibility of the bacterial species. The test showed that the isolates were susceptible to the LAB isolates as zones of inhibition were observed. The inhibition zones diameter obtained ranged from 8.35±1.34mm to 13.77±2.21mm. Avocado pear, asides from their high nutritional content, also have the potential to serve as source of probiotic bacteria.

Pomegranate Peel Flour as a Co-encapsulant Improves the Survival of Lactic Acid Bacteria to Thermal Treatment and Simulated Gastrointestinal Conditions

AbstractPomegranate peel flour was employed as a co-encapsulant of two lactic acid bacteria, by alginate emulsion templated microencapsulation, to enhance their resistance to thermal treatment, acidic pHs, and gastric conditions. Samples with pomegranate peel flour increased the tolerance to heat treatment, results consistent with thermal properties related to higher denaturation enthalpy of microcapsules. Co-encapsulated microcapsules also enhanced the survival to low pHs and enhanced almost 60% up the tolerance to bile salts. There was also an increase in survival rate against in vitro gastric acid conditions due to use of the co-encapsulant. In scanning electron microscopy, the incorporation of pomegranate peel flour resulted in a rough and porous structure, probably due to certain interference with the formation of spherical microcapsules, although it presented similar mean diameter, plus higher cell viability as confirmed by confocal laser microscopy. The obtained results indicate that co-encapsulation with a prebiotic ingredient represents a reinforcement of the physical microcapsule integrity to tolerate food process temperatures, besides retarding the adverse effect of acidic, bile salts, and simulated gastrointestinal conditions. The micro alginate co-encapsulation by ionic gelation with a prebiotic as pomegranate peel flour is a suitable alternative to develop thermal processed functional foods.

Comparison of in vitro digestive characteristics of proteins from different sources in simulated elderly gastrointestinal conditions

This study aimed to evaluate the impact of in vitro digestive characteristics of five different protein sources (fish, crab, beef, chicken, and soy) in adults and elderly individuals. Simulated gastrointestinal tract degradation in the elderly significantly reduced the digestibility of all proteins. The Elderly model had difficulties digesting any protein that had a firm structure or was prone to aggregation. Of the five protein types, soy protein was the least easily digested. Ultraviolet spectroscopy and SDS-PAGE analysis revealed that beef and crab proteins contain myoglobin and hemocyanin, respectively, making their structure firm. Simultaneously, alkali-soluble proteins in meat were more likely to be digested by the elderly than salt-soluble proteins. The alkali-soluble protein percentage in fish protein was the highest, including the best in vitro digestion characteristics in the elderly population. This study provides novel and significant recommendations for the elderly's daily intake of various protein sources.