Effect of storage temperatures and duration on quality of prepared chicken breast with paprika oleoresin

Changes in nitrosohemachrome lead to the discoloration of spiced beef during storage

The discoloration of spiced beef during storage is a severe problem that limits the shelf life of products. This study explored the associations between discoloration and pH, water, lipid oxidation, and protein oxidation. Electron paramagnetic resonance and UV-Vis spectroscopy illustrated that the pigment of spiced beef was a pentacoordinate mononitrosylheme compound and its conjugated structure changed during storage. The low-field NMR and magnetic resonance imaging results showed that the mobility of water increased, and the water content decreased with the extension of storage time. Multivariate analysis showed that color attributes were negatively correlated with oxidation. The oxidation of nitrosohemachrome was the primary reason for the lightness (L*) and redness (a*) decline in spiced beef. In addition, water loss exerted a promotion function in the oxidation process. This study provides valuable information on maintaining the quality of spiced beef during storage.

Proteins associated with quality deterioration of prepared chicken breast based on differential proteomics during refrigerated storage

BACKGROUND

Prepared chicken breast deterioration is a complex biochemical process, of which protein change is one of the main features. The present research focuses on the analysis of proteins related to the deterioration in quality of prepared chicken breast through differential proteomics analysis.

RESULTS

The physicochemical indexes of prepared chicken breast showed that quality gradually decreased at the second week of refrigerated storage, while the deterioration of chicken breast meat was obvious at the third week. Three key time points of quality change were determined to be at 0th, 2th and 5th week, respectively. In addition, 39 differential proteins were successfully identified using two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Most of the identified proteins showed significant differences in expression at the three key points of storage, of which actin, myosin, α-1,4-glucan phosphorylase, phosphoglucomutase 1, heat shock protein β-1, tubulin β-7 chain and skeletal muscle type tropomodulin (fragment) were closely related to the quality deterioration of prepared chicken breast, and thus potential indicator proteins to evaluate the quality of chicken breast.

CONCLUSION

The current study indicated that the physicochemical quality of prepared breast notably changed during refrigerated storage. Three key time points of quality change in the storage process of prepared chicken breast were determined. Furthermore, differential proteomics identified the key proteins related to freshness, which provides a theoretical basis for exploring the mechanism of chicken breast deterioration. © 2020 Society of Chemical Industry.

Characteristics of low-nitrite pork emulsified-sausages with paprika oleoresin solution during refrigerated storage

The objective of this study was to evaluate quality characteristics of low-nitrite emulsified-sausages (ESs, < 75 ppm) containing paprika oleoresin solution (POS) for replacing sodium nitrite (NaNO₂). Pork ESs were prepared with four treatments (reference (REF), 150 ppm NaNO₂; TRT1, 0 ppm NaNO₂ + 0.1% POS; TRT2, 37.5 ppm NaNO₂ + 0.1% POS; and TRT3, 75 ppm NaNO₂ + 0.1% POS). The physicochemical and texture properties, microbial counts, residual nitrite and thiobarbituric acid reactant substances (TBARS) were measured during refrigerated storage of 35 days. Although TRT2 and TRT3 had lower levels of NaNO₂, they had higher redness and yellowness than REF (p < 0.05). Microbial counts of total bacterial counts and Enterobacteriaceae of TRT2 and TRT3 were similar to those of REF (p > 0.05). Expressible moisture percentages (EM, %) of TRT2 and TRT3 were lower than those of REF (p < 0.05). TBARS values of TRT2 and TRT3 were not different from those of REF (p > 0.05). Among treatments, TRT1 had the highest TBARS values (p < 0.05). In conclusion, 0.1% POS in combination with 37.5 ppm NaNO₂ would have quality characteristics similar to those of REF. Therefore, approximately 3/4 of the initial nitrite level could be replaced with 0.1% POS, and eventually developed healthier pork products.

Comparison of two kinds of peroxyl radical pretreatment at chicken myofibrillar proteins glycation on the formation of Nε-carboxymethyllysine and Nε-carboxyethyllysine

During meat processing, two typical advanced glycation end products (AGEs), N^ε-carboxymethyllysine (CML) and N^ε-carboxyethyllysine (CEL), are generated by free radical induction. However, the impact of peroxyl radicals on myofibrillar proteins (MPs) glycosylation and CML and CEL formation is scarcely reported. In this study, two peroxyl radicals called ROO· and LOO· derived from AAPH (2,2'-azobis (2-methylpropionamidine) dihydrochloride) and linoleic acid were exposed prior to the Maillard reaction (glucosamine incubation at 37 °C for 24 h). Levels of AGEs (CML/CEL), protein oxidation (sulfhydryl/carbonyl), free amino group, surface hydrophobicity, zeta potential, particle size, intrinsic fluorescence intensity and secondary structure were determined. Together with Pearson's correlation, the assumption that free radicals promote MPs oxidation and glycation, alter the aggregation behavior and structure modification, leading to AGEs promotion has been built. In addition, the effect of dose-dependency of peroxyl radical on AGEs has also been established with different effects of peroxyl radical induction.