Structural and sensory characteristics of ultrasonic assisted wet-heating Maillard reaction products of Giant salamander protein hydrolysates.

BACKGROUND: Chinese giant salamander protein hydrolysates (CGSPH) are beneficial to human health as a result of their high content of amino acids and peptides. However, the formation of bitter peptides in protein hydrolysates (PHs) would hinder their application in food industry. The ultrasound assisted wet-heating Maillard reaction (MR) is an effective way to improve the flavor of PHs. Thus, the effect of ultrasonic assisted wet-heating MR on the structure and flavor of CGSPH was investigated in the present study. RESULTS: The results indicated that the ultrasound assisted wet-heating MR products (MRPs) exhibited a higher degree of graft and more significant changes in the secondary and tertiary structures of CGSPH compared to traditional wet-heating MRPs. Moreover, ultrasound assisted wet-heating MR could significantly increase the content of small molecule peptides and reduce the content of free amino acids of CGSPH, which resulted in more significant changes in flavor characteristics. The changed in flavor properties after MR (especially ultrasound assisted wet-heating MRPs) were mainly manifested by a significant reduction in bitterness, as well as a significant increase in the content of aromatic aldehyde ester compounds such as furan-2-carbaldehyde, butanal, benzaldehyde, furfural, etc. CONCLUSIONS: Ultrasound assisted wet-heating MR between CGSPH and xylose could be a promising way to improve the sensory characteristics of CGSPH. © 2024 Society of Chemical Industry.

Physicochemical and functional characteristics of glycated collagen protein from giant salamander skin induced by ultrasound Maillard reaction.

Chinese giant salamander skin collagen (CGSSC) was successfully conjugated with glucose (Glu)/xylose (Xy) by ultrasound Maillard reaction (MR) in nature deep eutectic solvents (NADES). The effects of ultrasound and reducing sugar types on the degree graft (DG) of MR products (MRPs), as well as the influence of DG on the structure and functional properties of MRPs were investigated. The results indicated that the ultrasound assisted could markedly enhance the MR of CGSSC, and low molecular weight reducing sugars were more reactive in MR. The ultrasound MR significantly changed the microstructure, secondary and tertiary structures of CGSSC. Moreover, the free sulfhydryl content of MRPs were increased, thus enhancing the surface hydrophobicity, emulsifying properties and antioxidant activity, which were positively correlated with DG. These findings provided theoretical insights into the effects of ultrasound assisted and different sugar types on the functional properties of collagen induced by MR.

Characteristics and antioxidant properties of Harpadon nehereus protein hydrolysate-xylose conjugates obtained from the Maillard reaction by ultrasound-assisted wet heating in a natural deep eutectic solvents system.

BACKGROUND: Harpadon nehereus is a high-protein marine fish. A valuable way to add value to H. nehereus is to convert it into protein hydrolysate. The Maillard reaction is an effective way to improve the functional properties of peptides and proteins, which are affected by many factors such as reactant concentration, water activity, pH, temperature, and heating time. However, the traditional Maillard reaction method is inefficient. The purpose of this study was therefore to explore the effect of the ultrasound-assisted wet heating method on the Maillard reaction of H. nehereus protein hydrolysate (HNPH) in a new-type green solvent - a natural hypereutectic solvent (NADES). RESULTS: Harpadon nehereus protein hydrolysate-xylose (Xy) conjugates were prepared via a Maillard reaction in a NADES system using an ultrasound-assisted wet heating method. The effects of different treatment conditions on the Maillard reaction were studied. The optimized glycation degree (DG) of HNPH-Xy conjugates was obtained with a water content of 10%, a reaction temperature of 80 °C, a reaction time of 35 min, and an ultrasonic power level of 300 W. Compared with HNPH, the structure of HNPH-Xy conjugates were significantly changed. Moreover, the functional properties and antioxidant activity of HNPH-Xy were all superior to the HNPH. CONCLUSIONS: An ultrasound-assisted wet-heating Maillard reaction between HNPH and Xy in the NADES system could be a promising way to improve the functional properties of HNPH. © 2023 Society of Chemical Industry.

Effect of tea polyphenols on sturgeon myofibrillar protein structure in the in vitro anti-glycation model mediated by low temperature vacuum heating.

The binding mechanism between tea polyphenols and sturgeon myofibrillar protein (SMP) in the early stage (0, 2, 4 min), middle stage (6, 10 min) and late stage (15 min) of low temperature vacuum heating (LTVH) in an in vitro anti-glycation model was investigated. The result indicated that the protein cross-linking during LTVH treatment were mainly induced by tea polyphenols. The loss rate of free arginine (Arg) and free lysine (Lys) of SMP at the late stage of LTVH treatment (15 min) was 73.95 % and 83.16 %, respectively. The hydrophobic force and disulfide bond were the main force between tea polyphenols and SMP in the middle and late stage of LTVH treatment. The benzene ring and phenolic hydroxyl group of tea polyphenols can interact with the amino acid residues of SMP, which was exothermic and entropy-increasing. This study provides new insights in the interaction mechanisms between tea polyphenols-protein during heat treatment process.

Efficient expansion of mesenchymal stem cells from mouse bone marrow under hypoxic conditions.

To realize the therapeutic potential of mesenchymal stem cells (MSCs), a large number of high-quality MSCs isolated from different species, such as mouse, were acquired for preclinical animal studies. Surprisingly, isolation and purification of mouse MSCs (mMSCs) is arduous because of the low frequency of MSCs and contamination of haematopoietic cells in culture. We have developed a method based on low density and hypoxic culture to isolate and expand mMSCs from different strains, including BALB/c, C57BL/6J, FVB/N and DBA/2. The cells from all of the strains expanded more rapidly when plated at low density in hypoxic culture compared with normoxic culture. These cells expressed CD44, CD105, CD29 and Sca-1 markers but not CD11b, CD34, CD45 and CD31 markers. Moreover, they were able to differentiate along osteoblastic, adipocytic and chondrocytic lineages. In conclusion, we have developed a robust method for isolation and expansion of mMSCs by combining low-density culture with hypoxic culture.