Effect of oligosaccharides as lyoprotectants on the stability of curcumin-loaded nanoliposomes during lyophilization

Exploring the Effects of Freeze-Dried Sourdoughs with Lactiplantibacillus pentosus 129 and Limosilactobacillus fermentum 139 on the Quality of Long-Fermentation Bread

Sourdough production is a complex fermentation process. Natural sourdough fermentation without standardization causes great variability in microbial communities and derived products. Starter cultures have emerged as alternatives to natural fermentation processes, which could improve bakery quality and produce bioactive compounds. This study aimed to evaluate the impacts of freeze-drying on the production and viability of sourdoughs with Lactiplantibacillus pentosus 129 (Lp) and Limosilactobacillus fermentum 139 (Lf), as well as their effects on the quality of long-fermentation bread. These strains were selected based on their better performance considering acidification and exopolysaccharide production capacity. Sourdough with Lp and Lf were propagated until the 10th day, when physicochemical and microbiological parameters were determined. The produced sourdoughs were freeze-dried, and bread samples were produced. The freeze-drying process resulted in high survival rates and few impacts on the metabolic activity of Lp and Lf until 60 days of storage. Incorporating Lp and Lf improved the microbiological and physicochemical properties of sourdough and long-fermentation breads. Tested freeze-dried sourdoughs led to reduced bread aging (higher specific volume and decreased starch retrogradation) and increased digestibility. The results show the potential of the freeze-dried sourdoughs produced with Lp and Lf as innovative strategies for standardizing production protocols for the bakery industry, especially for producing long-term fermentation bread.

The novel lactoferrin and DHA-codelivered liposomes with different membrane structures: Fabrication, in vitro infant digestion, and suckling pig intestinal organoid absorption

Inspired by membrane structure of breast milk and infant formula fat globules, four liposomes with different particle size (large and small) and compositions (Single phospholipids contained phosphatidylcholine, complex phospholipids contained phosphatidylcholine, phosphatidylethanolamine and sphingomyelin) were fabricated to deliver lactoferrin and DHA. In vitro infant semi-dynamic digestive behavior and absorption in intestinal organoids of liposomes were investigated. Liposomal structures were negligible changed during semi-dynamic gastric digestion while damaged in intestine. Liposomal degradation rate was primarily influenced by particle size, and complex phospholipids accelerated DHA hydrolysis. The release rate of DHA (91.7 ± 1.3 %) in small-sized liposomes (0.181 ± 0.001 μm) was higher than free DHA (unencapsulated, 64.6 ± 3.4 %). Complex phospholipids liposomal digesta exhibited higher transport efficiency (3.4-fold for fatty acids and 2.0-fold for amino acids) and better organoid growth than digesta of bare nutrients. This study provided new insights into membrane structure-functionality relationship of liposomes and may aid in the development of novel infant nutrient carriers.

Thermal stability and in vitro biological fate of lactoferrin-polysaccharide complexes

Lactoferrin (LF) is a thermally sensitive iron-binding globular glycoprotein. Heat treatment can induce its denaturation and aggregation and thus affect its functional activity. In this study, carrageenan (CG), xanthan gum (XG) and locust bean gum (LBG), allowed to apply in infant food, were used to form protein-polysaccharide complexes to improve the thermal stability of LF. Meanwhile, in vitro simulated infant digestion and absorption properties of LF were also estimated. The results showed that the complexes formed by CG and XG with LF (LF-CG and LF-XG) could significantly inhibit the loss of α-helix structure of LF against heating. LF-CG and LF-LBG could protect LF from digestion in simulated infant gastric fluid and slow down the degradation of LF under the simulated intestinal conditions. Besides, LF, LF-CG and LF-XG showed no adverse effects on the growth of Caco-2 cells in the LF concentration range of 10-300 μg/mL, and LF-XG exhibited better beneficial to improve the cell uptake of the digestive product than the other protein-polysaccharides at the LF concentration of 100 µg/mL. This study may provide a reference for the enhancement of thermal processing stability of LF and development infant food ingredient with high nutrients absorption efficiency in the gastrointestinal environment in the future.

Specific protection mechanism of oligosaccharides on liposomes during freeze-drying

Liposomes have been received much attention during the past decades as bioactive compounds carriers in food field. However, the application of liposomes is extremely limited by the structural instability during processing such as freeze-drying. In addition, the protection mechanism of lyoprotectant for liposomes during freeze-drying remains controversial. In this study, lactose, fructooligosaccharide, inulin and sucrose were used as lyoprotectants for liposomes and the physicochemical properties, structural stability and freeze-drying protection mechanism were explored. The addition of oligosaccharides could significantly suppress the changes in size and zeta potential, and the amorphous state of liposomes was negligible changed from XRD. The T_g of the four oligosaccharides, especially for sucrose (69.50 °C) and lactose (95.67 °C), revealed the freeze-dried liposomes had formed vitrification matrix, which could prevent liposomes from fusion via increasing the viscosity and reducing membrane mobility. The decrease in T_m of sucrose (147.67 °C) and lactose (181.67 °C), and the changes in functional group of phospholipid and hygroscopic capacity of lyophilized liposomes indicated oligosaccharides replaced water molecules to interact with phospholipids by hydrogen bonds. It can be concluded that the protection mechanism of sucrose and lactose as lyoprotectant was attributed to the combination of vitrification theory and water replacement hypothesis, while the water replacement hypothesis was dominated by fructooligosaccharide and inulin.