Evaluation of the effects of compound curing agents on the lipid profiles and volatile flavors in Nuodeng ham based on lipidomics and GC-IMS analysis.

Eighteen raw legs were evenly divided into two groups and salted with 100% NaCl and compound curing agent (60% NaCl + 40% KCl + 90 mg/kg NaNO2) to investigate the effect of compound curing agent on lipid metabolites and volatile flavor compounds in Nuodeng ham. The results of UHPLC-QE-MS and GC-IMS combined with multivariate statistical analysis showed that 27 lipid metabolites and 30 characteristic volatile flavor compounds were identified as characteristic markers in different treatment groups. The compound curing agent promoted the release of TG, SQDG, Hex1Cer, and LPC in Nuodeng ham, and accelerated the formation of volatile compounds such as 2-propanone, nonanal-d, gamma-butyrolactone, ethhyl acetate and benzeneacetaldehyde et al. Through correlation analysis, ketones were positively correlated with some PUFAs and negatively correlated with most MUFAs. Processing Nuodeng ham with compound curing agents has a positive effect on improving its quality. These findings provide a scientific theoretical basis for the development and utilization of compound curing agent.

The effects of long-term freezing-thawing on the strength properties and the chemical stability of compound solidified/stabilized lead-contaminated soil.

Solidification/stabilization (S/S) is the prevalent remediation technology for the treatment of heavy metal contaminated soils (HMCS). However, under the stress of complex surrounding environments, S/S effectiveness tends to deteriorate and freezing-thawing is one of the most influential natural forcings. The different proportions of cement, lime, and fly ash were used as the compound curing agents to treat solidified/stabilized HMCS with varying levels of lead contamination. The resulting samples were subjected to up to 180 freeze-thaw cycles (F-T) (1 day per cycle). Unconfined compressive strength (UCS) tests and semi-dynamic leaching tests were performed after F-T to explore the strength evolution of compound solidified/stabilized lead-contaminated soils (Pb-CSCS) and the chemical stability of the lead within. The results show that the F-T duration changes the strength deterioration mechanism of Pb-CSCS under F-T. There has been a shift in the main influencing factor from the promoted curing agent hydration by short-term F-T to the structural damage of the specimen induced by prolonged F-T. The variations in leachate pH, lead leachability, and diffusion ability with progressing F-T revealed a degradation effect of the changes in the physical states of water and crack propagation brought by F-T. These unfavorable changes in soil structure and chemistry reduce the acid resistance of Pb-CSCS. Notably, fly ash and cement facilitate the strength maintenance of Pb-CSCS under long-term F-T conditions. Curing formulations that included both cement and fly ash significantly increased the UCS of treated soils by up to 80.5% (3 F-T) under short-term F-T. In contrast, the curing formulation without fly ash lost 51.8% of its strength after 180 F-T conditions. For lead stabilization, cement and especially lime are favored. The results showed a 25% increase in the total proportion of lime and cement in the curing agent formulation, leading to a 41.4% reduction of lead leaching risk.