Influence of salting process on the structure and in vitro digestibility of actomyosin.

Salting process is widely used in the process of meat products, whereas few studies have revealed the digestibility of actomyosin after salting treatment, which is closely related with the nutrition of meat. This work reported effect of salting on the structural change and digestibility of actomyosin before and after heat treatment. Actomyosin in 0.4 M and 0.8 M of NaCl had higher content of disulfide bonds, and actomyosin in 0.4 M NaCl showed the largest particle sizes before and after heat treatment. In addition, actomyosin in 0.6 M and 0.8 M of NaCl was oxidized more severely after heat treatment. Based on peptidomics analysis by using liquid chromatography tandem mass spectrometry (LC-MS/MS), actomyosin in 0.6 M was digested more easily, which was followed by sample in 0.8 M and 0.4 M of NaCl in descending order. The lowest digestibility of actomyosin in 0.4 M NaCl was related with its higher content of disulfide bond and severer aggregation behavior. The lower digestibility of actomyosin in 0.8 M NaCl should be related with the higher content of disulfide bonds and surface oxidation. These results highlight the crucial role of salting process in affecting the digestibility of meat protein.

PACAP38 improves airway epithelial barrier destruction induced by house dust mites allergen.

PURPOSE: This study aimed to investigate the mechanism of PACAP38 on house dust mite (HDM)-induced asthmatic airway epithelial barrier destruction. METHODS: The HDM-induced asthma mice model and 16HBE cell model was established respectively. The enzyme linked immunosorbent assay (ELSIA), cell count and immunohistochemical assay were performed on mice in control group, HDM group and PACAP38 + HDM group.The cAMP/PKA activity, p-CREB and total CREB expression, TEER and the FITC-DX were investigated on cells in control-16HBE group, HDM-16HBE group and PACAP38 + HDM-16HBE group. RESULTS: The levels of IL-4 and IL-5 in the HDM group were significantly higher than those in the control group (P < 0.05), while the above indexes in the PACAP38 + HDM group were lower than those in the HDM group (P < 0.05). E-cadherin, ß-catenin, ZO-1 and occludin in the control group were highly immunoreactive in airway epithelial cells, whereas connexin staining was attenuated after HDM induction. The TEER level, cAMP levels and PKA activity were decreased, while FITC-DX transmittance was increased in HDM-16HBE group (P < 0.05) compared with the control-16HBE group. CONCLUSION: PACAP38 could reduce the airway inflammation, weaken the AJC protein heterotopia and activate cAMP/PKA signaling pathway in HDM-induced asthma, which indicate that PACAP38 may be an important contributor in HDM-induced asthma.

Raman spectroscopic study of heat-induced gelation of pork myofibrillar proteins and its relationship with textural characteristic.

Structural changes, textural properties and their relationships in pork myofibrillar proteins (PMP) were studied by Raman spectroscopy, texture profile analysis (TPA) and principal component analysis (PCA). Raman spectroscopy analysis revealed the occurrence of secondary structural changes in myofibrillar proteins. Modifications in the amide I (1600-1700 cm(-1)) and amide III (1200-1300 cm(-1)) regions indicated a significant (p<0.05) decrease in α-helix content, accompanied by a significant (p<0.05) increase in ß-sheets, ß-turns and random coil content. Texture property changes were also determined by TPA. All these features contributed to the formation of strong, irreversible heat-induced gels. The application of a dimensionality reducing technique such as PCA proved to be useful to determine the most influential properties of heat-induced gel. Significant (p<0.05) correlations were found between these structural changes and the textural characteristic (hardness) in the pork myofibrillar proteins system by PCA.