Influence of amino acids on thermal stability and heat-set gelation of bovine serum albumin

Effects of pasteurization temperature and amino acids on the gelation behavior of liquid egg yolk: Emphasizing rheology, gel properties, intermolecular forces and microstructure

Pipeline blockage caused by liquid egg yolk (LEY) in the pasteurization process has become an urgent problem for egg industry. This study investigated the effects of amino acids (betaine/proline) on rheology of LEY and gel property of egg yolk gel (EYG) at various pasteurization temperatures (68, 72, and 76 °C). Rheological results revealed that 72 °C was the key transition point for increase in LEY thermal aggregation rate. Average particle size of EYG, BEYG and PEYG increased by 63.9 %, 27.3 % and 17.3 % with increasing pasteurization temperature. Amino acids promoted increase in disulfide bonding content and facilitated retention of free and bound water within gels. Moreover, amino acids enhanced crystallinity and order of gel structures. Amino acids can effectively mitigate thermal aggregation of LEY at mild temperatures and promote cross-linking of gel network at high temperatures. This study provides a theoretical foundation for heat resistance of LEY and application of EYG.

Improvement of kefir fermentation on rheological and microstructural properties of soy protein isolate gels

Soy protein isolate (SPI) has become a promising plant-based material as an animal protein products alternative. However, its application was limited due to the weak gelling properties. To investigate the effect of kefir fermentation on SPI gels properties, SPI-polysaccharide gels was produced by unfermented and kefir-fermented SPI using different concentration of KGM, chitosan, and calcium chloride in this study. Characterization of fermented SPI gels showed that fermentation by kefir grains can be applied to improve the textural strength, mechanical structure, and thermal characteristics of SPI gels. Compared to unfermented SPI gels, the water-holding capacity was remarkably enhanced to 63.11% and 65.71% in fermented SPI-chitosan gels. Moreover, the hardness of fermented SPI-KGM gels were significantly increased to 13.43 g and 27.11 g. And the cohesiveness and resilience of fermented-KGM gels were also improved than unfermented samples. Results of rheological characterization and thermogravimetric analysis revealed the strengthened mechanical features and higher thermal stability of fermented SPI gels. Additionally, the main role of hydrophobic interactions and secondary structure variations of SPI gels were demonstrated by intermolecular force measurements, Fourier-transform infrared spectroscopy, and X-ray diffraction. Moreover, the network structure was observed more compact and homogeneous performed by microstructural images in fermented SPI gels. Therefore, this research provided a novel approach combining multi-species fermentation with protein gelation to prepare SPI gel materials with improved nutrition and structural properties.

Increased Risk of Inflammatory Bowel Disease Among Patients With Ankylosing Spondylitis: A 13-Year Population-Based Cohort Study

Aim

Ankylosing spondylitis (AS) primarily affects the axial skeleton and extraarticular structures. Small-scaled studies have reported that the incidence and prevalence of inflammatory bowel disease (IBD) are higher in patients with AS than in the general population. This study determined the incidence of IBD in patients with AS using a large scale population-based cohort dataset.

Methods

This was a retrospective cohort study. Patient data were collected from the Taiwan National Health Insurance Research Database from 2000 to 2012. We enrolled 3,804 patients with AS and 7,608 non-AS patients. The endpoint was IBD diagnosis by using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) coding 555 and 556 after at least three outpatient visits or one hospital admission, until the end of 2012. The Kaplan-Meier analysis was performed to discriminate the cumulative incidence of IBD and the log-rank test was used to test the significance. A Cox proportional hazard model was used to estimate the hazard ratio (HR) for IBD between the AS and non-AS groups.

Results

Among the population as a whole the Cox proportional hazard regression indicated that patients aged ≥65 years [adjusted HR (aHR): 2.48, 95% confidence interval (CI): 1.38-4.47] or with comorbidity of cancer (aHR: 3.51, 95% CI: 1.40-8.80) had a higher HR for IBD. Kaplan-Meier curves of cumulative incidence proportion of IBD indicated that patients with AS had a higher risk of IBD than the non-AS group in the subgroup aged <40 years (HR: 2.85, 95% CI: 1.51-5.40, p = 0.001).

Conclusions

Patients with AS aged <40 years had a higher IBD risk than did those without AS in Taiwan. Clinicians and patients should be aware of this association.