Exploring the interactions between Lactobacillus rhamnosus GG and whey protein isolate for preservation of the viability of bacteria through spray drying

Wood hemicelluloses as protective materials for preserving the viability of probiotic Lacticaseibacillus rhamnosus GG during spray drying

Wood hemicelluloses from forest industry side-streams are promising economic and sustainable alternatives for encapsulating bioactive compounds. This study explores their suitability for probiotic encapsulation, specifically for maintaining cell viability and structure. The ability of galactoglucomannans (GGM) and glucuronoxylans (GX) to support the survival of Lacticaseibacillus rhamnosus GG (LGG) during spray drying at solid feed concentrations of 15 and 20 % and inlet air temperatures of 105 and 140 °C (outlet air temperature of 50 °C) was investigated and compared to the results obtained using maltodextrin (MD). Across all investigated conditions, LGG survival rates exceeded 85 % (>107 cfu/g) in GX and GGM microcapsule powders, which similar to that in MD microcapsules despite the differences in pH, particle size, and viscosity of their feed dispersions. The GX microcapsules demonstrated the highest process yield (50-58 %), followed by MD (39-51 %). All the microcapsule powders exhibited an amorphous structure consisting of spherical particles with an average diameter of 10 μm, sufficient for LGG accommodation. Atomic force microscopy analysis confirmed the encapsulation of LGG cells within microcapsules with intact rod-shaped chains post-spray drying. Overall, the spray-dried microencapsulation of probiotics using wood hemicelluloses maintains high probiotic viability and offers an eco-friendly, cost-effective alternative to traditional materials.

A protectant for Lactobacillus rhamnosus based on whey protein isolate and isomalt: Stress resistance and underlying mechanisms

Probiotics are exposed to a variety of abiotic and biotic stresses during food fermentation and production, such as acidity, heat, osmolality, and oxidation, which affect their metabolic activity and efficiency. Therefore, it is essential to develop new protective agents to maintain the activity and stability of probiotics. This study introduces a new protectant, spray-dried whey protein isolate (WPI) and isomaltose (ISO). We evaluated the effects of four WPI-ISO ratios (1:0, 2:1, 1:1, 1:2) on the physical properties, including moisture content, water activity (aw), wettability, and glass transition temperature. In addition, we evaluated the environmental tolerance of Lactobacillus rhamnosus to different WPI-ISO ratios under thermal, storage, and simulated gastrointestinal conditions. The results showed that the moisture content (< 7 %) and water activity (< 0.3) of the protectant and probiotic powders met storage stability requirements. The moisture content, water activity, wettability index (WI), and glass transition temperature decreased significantly with the addition of isomalt, thereby improving the pressure resistance of L. rhamnosus through the synergistic effect of WPI and ISO. The WPI-ISO protectant not only improved the environmental tolerance and wettability of probiotics by reducing the moisture content and water activity but also significantly improved the survival rate of L. rhamnosus under various stress conditions such as high temperature and gastrointestinal environment. L. rhamnosus maintains good activity with a viable bacterial count of over 9 lg CFU/g after 90 days of storage, demonstrating effective protection against the environment stress. This study provides a promising new strategy to improve the stability of probiotics in the food industry.

Screening of Lactiplantibacillus plantarum 67 with Strong Adhesion to Caco-2 Cells and the Effects of Protective Agents on Its Adhesion Ability during Vacuum Freeze Drying

Adhesion to the intestinal tract provides the foundation for Lactobacillus to exert its benefits. Vacuum freeze-drying (VFD) is currently one of the main processing methods for Lactobacillus products. Therefore, the effects of VFD on the adhesion and survival of Lactiplantibacillus plantarum 67 were investigated in this study. The results show that L. plantarum 67 exhibits remarkable tolerance following successive exposure to simulated saliva, gastric juice and intestinal juice, and also has a strong adhesion ability to Caco-2 cells. The adhesion and survival rates of L. plantarum 67 significantly decreased after VFD in phosphate-buffered saline (PBS), whereas they significantly increased in protective agents (PAs) (p < 0.05). Scanning electron microscope observations show that L. plantarum 67 aggregated more to Caco-2 cells in PAs than in PBS, and its shape and size were protected. Proteomics detection findings indicated that differentially expressed proteins (DEPs) related to adhesins and vitality and their pathways in L. plantarum 67 were significantly affected by VFD (p < 0.05). However, the expression of DEPs (such as cold shock protein, cell surface protein, adherence protein, chitin-binding domain and extracellular transglycosylase, membrane-bound protein) was improved by PAs. Compared with PBS, the PAs significantly adjusted the phosphotransferase system and amino sugar and nucleotide sugar metabolism pathways (p < 0.05). VFD decreased the adhesion and vitality of L. plantarum 67, while the PAs could exert protective effects by regulating proteins and pathways related to adhesion and vitality.

Advances in spray-dried probiotic microcapsules for targeted delivery: a review

Probiotics have gained significant attention owing to their roles in regulating human health. Recently, spray drying has been considered as a promising technique to produce probiotic powders due to its advantages of high efficiency, cost-saving, and good powder properties. However, the severe environmental conditions from drying and digestion can significantly reduce cell viability, resulting in poor bioaccessibility and bioavailability of live cells. Therefore, there is a need to develop effective targeted delivery systems using spray drying to protect bacteria and to maintain their physiological functions in the targeted sites. This review highlights recent studies about spray-dried targeted delivery vehicles for probiotics, focusing on key strategies to protect bacteria when encountering external stresses, the formation mechanism of particles, the targeted release and colonization mechanisms of live cells in particles with different structures. Advances in the targeted delivery of live probiotics via spray-dried vehicles are still in their early stages. To increase the possibilities for industrialization and commercialization, functional improvement of microcapsules in terms of protection, targeted release, and colonization of bacteria, as well as the effect of spray drying on bacterial physiological functions in the host, need to be further investigated.

Characterization, High-Density Fermentation, and the Production of a Directed Vat Set Starter of Lactobacilli Used in the Food Industry: A Review

Lactobacilli have been widely concerned for decades. Bacteria of the genus Lactobacillus have been commonly employed in fermented food to improve the appearance, smell, and taste of food or prolong its shelf-life. They comprise 261 species (by March 2020) that are highly diverse at the phenotypic, ecological, and genotypic levels. Some Lactobacilli strains have been documented to be essential probiotics, which are defined as a group of living microorganisms that are beneficial to the health of the host when ingested in sufficiency. However, the characterization, high-density fermentation, and the production of a directed vat set (DVS) starter of Lactobacilli strains used in the food industry have not been systematically reported. This paper mainly focuses on reviewing Lactobacilli as functional starter cultures in the food industry, including different molecular techniques for identification at the species and strain levels, methods for evaluating Lactobacilli properties, enhancing their performance and improving the cell density of Lactobacilli, and the production techniques of DVS starter of Lactobacilli strains. Moreover, this review further discussed the existing problems and future development prospects of Lactobacilli in the food industry. The viability and stability of Lactobacilli in the food industry and gastrointestinal environment are critical challenges at the industrial scale. The new production equipment and technology of DVS starter of Lactobacilli strains will have the potential for large-scale application, for example, developing low-temperature spray drying, freezing granulation drying, and spray freeze-drying.

Trehalose improves palmitic acid-induced apoptosis of osteoblasts by regulating SIRT3-medicated autophagy via the AMPK/mTOR/ULK1 pathway

Accumulation of lipid substances decreased the activity of osteoblasts. Trehalose is a typical stress metabolite to form a protective membrane on cell surface which has been demonstrated to regulate lipid metabolism. This activity of Trehalose indicates the potential effect of osteoporosis treatment. Our study aimed to determine the therapeutic effect of Trehalose in high fat-induced osteoporosis. We used palmitic acid (PA) to mimic the state of high fat and observed the apoptosis ratio of osteoblasts increased. After adding Trehalose, the apoptosis ratio decreased obviously. Autophagy is a regulatory means involved in the process of apoptosis. We detected the autophagy protein and found that the expression of Beclin-1, Atg5, and LC3 II increased, and p62 decreased after Trehalose treatment. When adding an autophagy inhibitor (3-MA), the expression of Beclin-1, Atg5, and LC3 II decreased, and p62 increased. These results indicated autophagy was an important factor involved in the preventive effect of Trehalose in PA-induced apoptosis. SIRT3 is a mitochondrial gene that can inhibit apoptosis, which has been reported to promote autophagy. We used SIRT3-siRNA to silence the expression of SIRT3 and found the effect of Trehalose was counteracted. The apoptosis ratio increased and the expression of Beclin-1, Atg5, and LC3 II decreased, p62 increased. Additionally, we also fed the mice with a high-fat diet (HFD) and intragastrical Trehalose. The results showed that Trehalose could inhibit the bone mass loss with HFD. Our study revealed the effect and mechanism of Trehalose in the treatment of osteoporosis.