Uncovering the rheological properties basis for freeze drying treatment-induced improvement in the solubility of myofibrillar proteins.

Myofibrillar proteins (MPs) are an important nutritional supplement and have great significance in sports training and rehabilitation therapy. Currently, MPs preservation is still disputed since they are vulnerable to degradation, polymerization, and denaturation. Freeze-drying is an emerging technology for protein preservation, its effects on the functionality of MPs from different sources have not yet been thoroughly studied. This study aims to evaluate the performance differences of freeze-drying in maintaining the functional characteristics of MPs from fish and mammalian sources, providing valuable insights for the processing and preservation of MPs, and providing nutritional support for nursing and rehabilitation. The results showed that freeze-drying was an efficient method for protein preservation, and the effects of freeze-drying on both fish and mammalian sources MPs were significant (p < 0.05) consistent. Specifically, whether before and after freeze-drying, the solubility of fish MPs (FMPs) was significant (p < 0.05) lower than that of mammalian MPs, while the foaming and emulsifying properties were significant (p < 0.05) higher than those of beef and sheep MPs (BMPs and SMPs, respectively). Furthermore, the most efficient protein concentration for freeze-drying was 10 mg/mL, and with this concentration, the gel strengths of BMPs and SMPs showed an insignificant difference (p > 0.05) after freeze-drying.

A study of the effect of hypothyroidism during pregnancy on human milk quality based on rheological properties.

Hypothyroidism has been found to have an effect on the nutritional composition of human milk during pregnancy. This study aims to explore the combined influence of rheological properties, macronutrient content, particle size, and the zeta potential of milk fat globules, as well as the composition of milk fat globule membrane (MFGM) proteins on the quality of human milk in gestational hypothyroidism. The study revealed that human milk from the group with hypothyroidism during pregnancy (AHM) was less viscoelastic and stable when compared with normal pregnancy group human milk (NHM). Furthermore, the particle size and macronutrient content of NHM were found to be larger than that of AHM. In contrast, the zeta potential of AHM was greater than that of NHM. The sodium dodecyl sulfate-PAGE results disclosed that the composition of MFGM proteins in these 2 groups were generally the same, but the content of AHM was lower than that of NHM. In conclusion, this study confirms that hypothyroidism during pregnancy can have a significant effect on the quality of human milk.

Comprehensive Screening for EPA/DHA-Structured Phospholipids in Aquatic Products by a Specific Precursor Ion Scanning-Based HILIC-MS/MS Method.

Comprehensive screening for functional substances from natural resources is always a hot research topic. Eicosapentaenoic acid- (EPA) and docosahexaenoic acid (DHA)-structured phospholipids (PLEPA/DHA) have versatile cardiovascular benefits as well as superior bioavailability. Herein, the abundance of PLEPA/DHA in 16 aquatic products was specifically and selectively screened using a recently developed precursor ion scan-driven hydrophilic interaction chromatography-mass spectrometry (PreIS-HILIC/MS) method with the fatty acyl moieties of EPA (m/z 301.6) and DHA (m/z 327.6) locked. The aim focused on the characteristics and differences in the varieties and contents of EPA/DHA-structured phosphatidylcholine (PCEPA/DHA) and EPA/DHA-structured phosphatidylethanolamine (PEEPA/DHA) molecular species. A total of 80 PLEPA/DHA molecules were identified in these natural sources, including 47 PCEPA/DHA and 33 PEEPA/DHA. After analysis, PC 16:0/20:5 and PC 16:0/22:6 are present in all aquatic products and at high levels. Antarctic krill was found to be the best resource of PLEPA/DHA in total (2574.69 µg·g-1), followed by mackerel (2330.11 µg·g-1), salmon (2109.91 µg·g-1), and Farrer's scallop (1883.59 µg·g-1), while abalone contained the lowest level of PLEPA/DHA (310.44 µg·g-1). Besides, sea cucumber and sea bass contained the highest contents of EPA-structured and DHA-structured ether phospholipids, respectively, which could be highly recommended as dietary sources of special functional phospholipids. Finally, the multiple discrepancies between the 16 aquatic products were revealed by multivariate statistical analysis. These findings improve the awareness of the composition and content of PLEPA/DHA contained in aquatic products, providing a reference for their integrated development.

Chain-locked precursor ion scanning based HPLC-MS/MS for in-depth molecular analysis of lipase-catalyzed transesterification of structured phospholipids containing ω-3 fatty acyl chains.

Lipase-catalyzed transesterification of structured phospholipids (sPLs) is a hot topic, but the structural variation of the fatty acyl chains in intact phospholipids at the molecular level remains unclear to date. The present study explored the detailed characteristics of synthesized phospholipids through high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) in precursor ion scan mode. The optimal conditions were in-depth inspected and determined for the reaction system, including phospholipase A1 as catalyst, 15% lipase loading, and 1% water content. The sPLs enriched with EPA/DHA were structurally and quantitatively characterized by focusing on the fragments of m/z 301.6 (eicosapentaenoic acid, EPA) and m/z 327.6 (docosahexaenoic acid, DHA), and the results were statistically analyzed using partial least squares discriminant analysis and clustered heatmap hierarchical clustering analysis. PC 38:6 (18:1/20:5), PC 38:7 (18:2/20:5), PC o-40:6 (o-18:0/22:6), and PE 40:8 (18:2/22:6) etc. were revealed as the main variables that were active in the reaction.

Insight into the effect of ultrasound treatment on the rheological properties of myofibrillar proteins based on the changes in their tertiary structure.

This was the first study to perform correlation analysis to determine the relationships between tertiary structural and rheological properties of the myofibrillar proteins (MPs) under ultrasound treatment (UT, frequency 20 kHz, power 500 W, intensity 30 %) for 0, 2, 4, 6, 8, and 10 min. The objectives of this study were to 1) characterize the changes of the small and large deformation rheological properties of MPs based on the tertiary structural changes; 2) determine relationships of rheological property, tertiary structural changes, and UT time. The results showed that UT could enhance the structural rigidity and the resistance of the system to permanent deformation observed in rheological tests. Besides, UT could unfold MPs, expose more hydrophobic amino acid residues to increase the surface hydrophobicity (S0-BPB), destroy disulfide bonds to increase the content of reactive sulfhydryl content (R-SH). The correlation analysis showed that the rheological properties of MPs could be improved by UT with a longer treatment time (0-10 min), while inevitably and significantly changing the tertiary structure of MPs (p < 0.05). These findings suggested that UT might be effective in the food-processing industry to change the structure of proteins and improve rheological properties.

The sex-specific influence of FTO genotype on exercise intervention for weight loss in adult with obesity.

The impact of exercise on weight loss varies significantly among individuals, and genes play a critical role. This study aims to explore whether the FTO gene variant (rs8050136) affects the influence of exercise on weight. The study initially recruited 240 Han Chinese adults with obesity, and 178 of them (101 men, 77 women, aged from 21 to 60) completed a 12-week moderate aerobic exercise programme. The participants were genotyped and obesity-related data were collected before and after the intervention. The intensity and the amount of exercise were precisely monitored. After the intervention, most obesity-related parameters of the participants showed a significant decrease. For muscle and lean body mass, significant change was only observed in males (P < 0.001) but not females (P = 0.205, P = 0.200 respectively). Importantly, for weight and BMI loss, we observed a genotype-by-gender interaction (P = 0.041, P = 0.042 respectively, adjusted for age, exercise time and baseline value). In the further analysis, after stratified for gender, the exercise-induced weight loss (P = 0.008), BMI loss (P = 0.010), muscle mass loss (P = 0.005) and lean body mass loss (P = 0.004) showed greater decrease in male subjects carrying at least one A allele compared to non-carriers. In conclusion, our study suggests that in Han Chinese population with obesity, carrying "obese risk gene" FTO (rs8050136) does not lead to the resistance to weight management intervention. More importantly, in male subjects, carrying FTO risk allele would even lose more weight than non-carriers after exercise intervention.HighlightsFor Han Chinese adults with obesity, carrying "obese risk gene" FTO could still achieve weight loss through exercise.Males carrying FTO risk allele would lose more weight than non-carriers after a 12-weeks exercise programme.