Minced Beef Meat Paste Characteristics: Gel Properties, Water Distribution, and Microstructures Regulated by Medium Molecular Mass of γ-Poly-Glutamic Acid

The influences of various m-γ-PGA (0.08-0.20%, w/w) concentrations on the properties of minced beef meat paste in terms of rheological properties, texture, moisture distribution, and microstructures were evaluated. The results indicated that m-γ-PGA enhanced the water-holding capacity, gel strength, texture, and whiteness of the minced beef meat paste. Based on the microstructural results, m-γ-PGA helped form a more organized and compact gel, thereby limiting the migration of water through the gel matrix. In contrast to the control group, the water-holding property, gel strength, and whiteness of minced meat paste gels with m-γ-PGA content of 0.12% increased from 75.89%, 584.51 g·cm, and 61.83 to 79.91%, 780.87 g·cm, and 62.54, respectively (p < 0.05), exhibiting the highest water-holding property and gel strength. Thus, m-γ-PGA exhibits great potential for minced meat paste products as a healthy gel water retainer and enhancer in low-fat meat products.

Fermented Milk Product Enriched with γ-PGA, Peptides and GABA by Novel Co-Fermentation with Bacillus subtilis and Lactiplantibacillus plantarum

Milk was co-fermented with Bacillus subtilis HA and Lactiplantibacillus plantarum EJ2014 to produce a dairy ingredient enriched with poly-γ-glutamic acid (γ-PGA) and γ-aminobutyric acid (GABA). The first fermentation of milk with B. subtilis HA resulted in a viscous broth with pH 6.56, 0.26% acidity, 1.40 mg/g tyrosine equivalent, and 17.21 U/g protease activity. The viable cell counts of B. subtilis indicated 8.74 log CFU/mL, and the consistency index of the alkaline fermented milk was 1.82 Pa·sn. In addition, 4.65% mucilage was produced with 35.93% γ-PGA content. The milk co-fermented by L. plantarum indicated 1.34% acidity and pH 4.91. The viable bacterial counts of B. subtilis decreased to 4.44 log CFU/mL, whereas those of L. plantarum increased to 9.42 log CFU/mL. Monosodium glutamate (MSG) as a precursor was effectively converted into γ-PGA by B. subtilis, and then residual MSG was completely converted into GABA by L. plantarum with a yield of 26.15 mg/g. Furthermore, the co-fermented milk produced volatiles, including hexanoic acid, 2,3-butanediol, and acetoin, which may be responsible for its aged cheese-like aroma.

In Situ-Forming Collagen/poly-γ-glutamic Acid Hydrogel System with Mesenchymal Stem Cells and Bone Morphogenetic Protein-2 for Bone Tissue Regeneration in a Mouse Calvarial Bone Defect Model

BACKGROUND

Bone marrow-derived mesenchymal stem cells (BMSCs) and bone morphogenetic protein-2 (BMP-2) have been studied for bone repair because they have regenerative potential to differentiate into osteoblasts. The development of injectable and in situ three-dimensional (3D) scaffolds to proliferate and differentiate BMSCs and deliver BMP-2 is a crucial technology in BMSC-based tissue engineering.

METHODS

The proliferation of mouse BMSCs (mBMSCs) in collagen/poly-γ-glutamic acid (Col/γ-PGA) hydrogel was evaluated using LIVE/DEAD and acridine orange and propidium iodide assays. In vitro osteogenic differentiation and the gene expression level of Col/γ-PGA(mBMSC/BMP-2) were assessed by alizarin red S staining and quantitative reverse-transcription polymerase chain reaction. The bone regeneration effect of Col/γ-PGA(mBMSC/BMP-2) was evaluated in a mouse calvarial bone defect model. The cranial bones of the mice were monitored by micro-computed tomography and histological analysis.

RESULTS

The developed Col/γ-PGA hydrogel showed low viscosity below ambient temperature, while it provided a high elastic modulus and viscous modulus at body temperature. After gelation, the Col/γ-PGA hydrogel showed a 3D and interconnected porous structure, which helped the effective proliferation of BMSCs with BMP-2. The Col/γ-PGA (mBMSC/BMP-2) expressed more osteogenic genes and showed effective orthotopic bone formation in a mouse model with a critical-sized bone defect in only 3-4 weeks.

CONCLUSION

The Col/γ-PGA(mBMSC/BMP-2) hydrogel was suggested to be a promising platform by combining collagen as a major component of the extracellular matrix and γ-PGA as a viscosity reducer for easy handling at room temperature in BMSC-based bone tissue engineering scaffolds.

An injectable collagen/poly(γ-glutamic acid) hydrogel as a scaffold of stem cells and α-lipoic acid for enhanced protection against renal dysfunction

We have developed a collagen/γ-PGA hydrogel as an injectable scaffold for use in MSC-based therapy against renal dysfunction.