Stability of bifidobacteria entrapped in goat's whey freeze concentrate and inulin as wall materials and powder properties.
de Liz Gabriela Rodrigues,Verruck Silvani,Canella Maria Helena Machado,Dantas Adriana,Garcia Sofia Grechi,Maran Bruna Marchesan,Murakami Fabio Seigi,Prudencio Elane Schwinden
Food research international (Ottawa, Ont.)
Goat's whey was submitted to two cycles of block freeze concentration process, resulting in concentrate 1 and concentrate 2. Concentrate 1 was added with 5 g of inulin and both concentrates were inoculated with Bifidobacterium animalis ssp. lactis BB-12, the concentrates were then denoted as feed solutions 1 and 2, respectively. Feed solutions were spray-dried, resulting in powder 1 and 2. The stability of the bifidobacteria entrapped within the powders was evaluated for both spray-dried powders stored at 4 °C and 25 °C for 60 days. The spray-dried powders were also evaluated in relation to their physical and thermal properties. It was noted that Bifidobacteria displayed increased stability at refrigeration temperature. Analysis of physical properties indicated that the addition of inulin resulted in increased water solubility. However, both spray-dried powders displayed less flowability, as well as a yellow-greenish color. By evaluating the spray-dried powders thermal properties, it was possible to confirm that goat whey concentrates behave as excellent wall materials.
10.1016/j.foodres.2019.108752
Heat Adaptation Improved Cell Viability of Probiotic Enterococcus faecium HL7 upon Various Environmental Stresses.
Shin YuJin,Kang Chang-Ho,Kim Woori,So Jae-Seong
Probiotics and antimicrobial proteins
The production of viable functional probiotics presupposes stability of strain features in the final product. In previous studies, Enterococcus faecium HL7 was found to have relatively higher cell viability after freeze-drying and the long-lasting resistance to heat (60 °C) as well as higher antimicrobial activities against some of fish and human pathogens among isolated strains. For heat adaptation, E. faecium HL7 cells were exposed to 52 °C for 15 min. After adaption, slight decreases of unsaturated membrane fatty acid ratios were confirmed through fatty acid analysis. Upon subsequent exposure to various stress conditions such as HO (0.01%), ethanol (20%), acid (pH 3), and alkali (pH 12), the survival rate of heat-adapted HL7 was 10-10-fold higher than that of non-adapted one. These results highlight the potential of preconditioning treatments for maximizing survival of probiotic bacteria during development of probiotic functional foods. The cross-protection afforded by acid against thermal stress may indicate that certain common protective mechanisms are induced by both heat and acid stress. These results can be applied to enhancing the cell viability during live cell formulation of E. faecium HL7 to be used as a potential probiotics in aquaculture.
10.1007/s12602-018-9400-4
Optimized production of poly (γ-glutamic acid) (γ-PGA) using Bacillus licheniformis and its application as cryoprotectant for probiotics.
Xavier Janifer Raj,Madhan Kumarr Mrithula Mahalakshmi,Natarajan Gopalan,Ramana Karna Venkata,Semwal Anil Dutt
Biotechnology and applied biochemistry
Bacteria produce poly (γ-glutamic acid) (γ-PGA), a polymer of l- or d-glutamic acid, as a defense response and have gained importance due to their applications in food and pharmaceutical industry. In the present investigation, production of γ-PGA using cost-effective carbon substrate, characterization of the produced polymer, and its application as cryoprotectant for selected freeze-dried probiotic bacteria were investigated. Central composite rotatable design of response surface methodology was used to study the main and the interactive effects of medium components: rice bran and casein peptone concentration. Rice bran at 35% (w/v) and casein peptone at 7.5% (w/v) were found to be optimal at an initial pH of 7.5, and incubation temperature of 37°C for 48 H produced 8.2 g/L γ-PGA on dry weight basis. The thermal properties such as melting temperature, heat of fusion, and thermal stability were also studied. Ten percent (w/v) of γ-PGA with 10 percent of sodium alginate (w/v) protected viability of Bifidiobacterium bifidum NCDC 235 and B. adolescentis NCDC 236 during freeze drying at -80 ˚C for 48 H. The γ-PGA synthesized by the reported bacterium with GRAS status is suitable for food and biomedical applications.
10.1002/bab.1879
Mg improves the thermotolerance of probiotic Lactobacillus rhamnosus GG, Lactobacillus casei Zhang and Lactobacillus plantarum P-8.
Yang Y,Huang S,Wang J,Jan G,Jeantet R,Chen X D
Letters in applied microbiology
Food-related carbohydrates and proteins are often used as thermoprotectants for probiotic lactobacilli during industrial production and processing. However, the effect of inorganic salts is rarely reported. Magnesium is the second-most abundant cation in bacteria, and commonly found in various foods. Mg homeostasis is important in Salmonella and has been reported to play a critical role in their thermotolerance. However, the role of Mg in thermotolerance of other bacteria, in particular probiotic bacteria, still remains a hypothesis. In this study, the effect of Mg on thermotolerance of probiotic lactobacilli was investigated in three well-documented probiotic strains, Lactobacillus rhamnosus GG, Lactobacillus casei Zhang and Lactobacillus plantarum P-8, in comparison with Zn and Na . Concentrations of Mg between 10 and 50 mmol l were found to increase the bacterial survival upon heat challenge. Remarkably, Mg addition at 20 mmol l led to a 100-fold higher survival of L. rhamnosus GG upon heat challenge. This preliminary study also showed that Mg shortened the heat-induced extended lag time of bacteria, which indicated the improvement in bacterial recovery from thermal injury. SIGNIFICANCE AND IMPACT OF THE STUDY:In order to improve the productivity and stability of live probiotics, extensive investigations have been carried out to improve thermotolerance of probiotics. However, most of these studies focused on the effects of carbohydrates, proteins or amino acids. The roles of inorganic salts in various food materials, which have rarely been reported, should be considered when incorporating probiotics into these foods. In this study, Mg was found to play a significant role in the thermotolerance of probiotic lactobacilli. A novel strategy may be available in the near future by employing magnesium salts as protective agents of probiotics during manufacturing process.
10.1111/lam.12716
Heat stability of Lactobacillus rhamnosus GG and its cellular membrane during droplet drying and heat treatment.
Liu Bin,Fu Nan,Woo Meng Wai,Chen Xiao Dong
Food research international (Ottawa, Ont.)
Dehydration and thermal stresses are generally considered as two mains factors deactivating probiotic cells during droplet drying, as typically in industrial spray drying for producing active dry probiotics. However, little is known about how cells respond to these interplaying stresses in the short period of drying. This study showed that dehydration process could alleviate the detrimental effect of thermal stress to a certain extent, evidenced by that probiotic cells could withstand higher temperature in a single droplet drying (SDD) process compared to sole heat treatment. During SDD at 90 °C, droplet temperature increased with time, and the inactivation of Lactobacillus rhamnosus GG (LGG) was initially observed at droplet temperature of 61-65 °C. By contrast, the transition from the maintenance of LGG viability to rapid deactivation occurred at around 54 °C in heat treatment without dynamic dehydration. Possible mechanisms for the enhanced thermotolerance were investigated from drying kinetics level and cellular level. The favorable temperature profile and the decrease in droplet water activity during drying may benefit cell survival. The cytoplasmic membrane of LGG was more stable at elevated temperatures of 60-65 °C during drying, which might be related to the high viscosity of semi-dried particles mitigating the leakage of intracellular substances. Trehalose demonstrated a strong thermoprotective effect over lactose in heat treatment, but the protection was less effective at the later stage of drying. These results dissected the influence of the interplaying stresses on probiotic cells for the first time during droplet drying and also suggested possible approaches for improving cell survival in dried particles. Components capable of protecting cellular membrane are recommended for developing protectant formulation in spray drying of probiotics.
10.1016/j.foodres.2018.06.006
Thermal stabilization of probiotics by adsorption onto porous starches.
Benavent-Gil Yaiza,Rodrigo Dolores,Rosell Cristina M
Carbohydrate polymers
Industrial processing factors, such as temperature, compromise the viability of probiotic cells. Objective was to develop a system to thermally stabilize probiotic bacteria based on porous starches and using biopolymers as coating materials (gelatinized starch, guar gum and xanthan gum). Porous starches from corn and rice starches, having controlled number and size of porous were used as supporting material. Scanning electron microscopy confirmed the adsorption of the microorganism, leading microcapsules with corn starch but aggregates with rice starch. Surface pores of rice starch increased the encapsulation yield of rice starch around 10%, but that effect was not observed in porous corn starch. The highest encapsulation yield was obtained with porous starches coated with gelatinized starch, which ranged from 92 to 100%. Microencapsulates made with porous starches with small pores, like the ones obtained with α-amylase, and coated with gelatinized starch resulted in the highest thermal resistance at 55 °C.
10.1016/j.carbpol.2018.06.044
Production of RS4 from rice starch and its utilization as an encapsulating agent for targeted delivery of probiotics.
Ashwar Bilal Ahmad,Gani Asir,Gani Adil,Shah Asima,Masoodi Farooq Ahmad
Food chemistry
The research reported in this article is based on the hypothesis that crosslinking of starch can make it a potential wall material for targeted delivery of probiotics by altering its digestion. Three probiotic strains namely Lactobacillus casei, Lactobacillus brevis and Lactobacillus plantarum were microencapsulated with resistant starch. Encapsulation yield (%) of resistant starch microspheres was in the range of 43.01-48.46. The average diameter of resistant starch microparticles was in the range of 45.53-49.29μm. Fourier transform infrared (FT-IR) spectroscopy of microcapsules showed peaks in the region of 900-1300cm and 2918-2925cm which corresponds to the presence of bacteria. Differential Scanning Calorimeter (DSC) showed better thermal stability of resistant starch microcapsules. Microencapsulated probiotics survived well in simulated gastrointestinal conditions and adverse heat conditions. The viability of the microcapsulated lactobacilli also remained high (>7 log cfu g) for 2months at 4°C. The results revealed that resistant starch is the potential new delivery carrier for oral administration of probiotics.
10.1016/j.foodchem.2017.06.110
A novel route for double-layered encapsulation of probiotics with improved viability under adverse conditions.
Feng Kun,Huang Ru-Meng,Wu Rui-Qing,Wei Yun-Shan,Zong Min-Hua,Linhardt Robert J,Wu Hong
Food chemistry
To improve the survivability of probiotics under the harsh conditions, a novel double-layered vehicle, which was developed by a one-step coaxial electrospinning procedure, was here used to encapsulate the probiotics. The morphology characterization analysis revealed that the electrospun fiber had a beaded morphology and core-shell structure. Probiotic cells were successfully encapsulated in the fibers (10 CFU/mg) and exhibited an oriented distribution along the fiber. Additionally, the encapsulation of core-shell fiber mat enhanced the tolerance of probiotic cells to simulated gastrointestinal conditions and no significant loss of viability was found (p > 0.05). Besides that, the encapsulated cells exhibited better thermal stability under heat moisture treatment, lower loss of viability (0.32 log CFU/mL) was occurred when compared with the free cells or encapsulated cells in uniaxial fiber mat. In conclusion, this double-layered vehicle presents a great potential in probiotic encapsulation and improving their resistant ability to the harsh conditions.
10.1016/j.foodchem.2019.125977
Directed mutation of β-glucanases from probiotics to enhance enzymatic activity, thermal and pH stability.
Sun Zhan-Bin,Xu Jia-Liang,Lu Xin,Zhang Wei,Ji Chao,Ren Qing
Archives of microbiology
β-glucanases are widely applied in biological control, brewing and feed industries; however, there are seldom studies of β-glucanases in probiotics. Here, β-glucanase genes were cloned from Bacillus licheniformis, Lactobacillus fermentum and L. johnsonii. β-glucanase genes, as blg, lfg and ljg isolated from B. licheniformis, L. fermentum and L. johnsonii were prokaryotic expressed to obtain recombinant strains BL, LF and LJ, respectively. Directed mutations in these genes were introduced by sequential error-prone PCR. Results showed that β-glucanase activities in three mutants mblg, mlfg and mljg were 1.94-, 2.72- and 1.29-fold higher than the BL, LF and LJ, respectively. Mutation sites analysis showed substitutions at Ser370Gly and Leu395Phe in mblg; Arg169His and Asn302Ser in mlfg; Val132Met, Ser226Asn, and Asp355Gly in mljg. Spatial structural predictions revealed the numbers and positions of α-helices and β-strands in the three mutants were altered, which might result in β-glucanase activity increasement. Analysis of β-glucanase properties revealed no significant differences in the optimal temperatures and pH between mutant and wild-type strains. However, mlfg and mljg exhibited greater thermal stability at 30-50 ℃ than the wild-type strains, and mblg improved pH stability compared with wild-type strain. This is the first report about β-glucanase-encoding genes in L. fermentum and L. johnsonii. These findings provide an efficient way to improve the activity of β-glucanase.
10.1007/s00203-020-01886-z
Improved Viability and Thermal Stability of the Probiotics Encapsulated in a Novel Electrospun Fiber Mat.
Feng Kun,Zhai Meng-Yu,Zhang Ying,Linhardt Robert J,Zong Min-Hua,Li Lin,Wu Hong
Journal of agricultural and food chemistry
For the enhancement of the probiotics' survivability, a nanostructured fiber mat was developed by electrospinning. The probiotic Lactobacillus plantarum was encapsulated in the nanofibers with fructooligosaccharides (FOS) as the cell material. Fluorescence microscope image and scanning electron microscopy (SEM) showed that viable cells were successfully encapsulated in nanofibers (mean diameter = 410 ± 150 nm), and the applied voltage had no significant influence on their viability ( P > 0.05). A significantly improved viability (1.1 log) was achieved by incorporating 2.5% (w/w) of FOS as the electrospinning material ( P < 0.001). Additionally, compared with free cells, the survivability of cells encapsulated in electrospun FOS/PVA/ L. plantarum nanofibers was significantly enhanced under moist heat treatment (60 and 70 °C). This study shows that the obtained nanofiber is a feasible entrapment structure to improve the viability and thermal stability of encapsulated probiotic cells and provides an alternative approach for the development of functional food.
10.1021/acs.jafc.8b02644