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• A paramagnetic Cu2+-induced magnetic resonance tuning (MRET) strategy is proposed. • A Cu–M-MRS immunosensor was constructed for detection of chlorpyrifos and Salmonella. • Fe 3 O 4 @PDA-Ab 2 was used for signal conversion by regulating the amount of Cu2+ ions. • The LOD for chlorpyrifos and Salmonella are 0.05 ng/mL and 50 CFU/mL, respectively. Magnetic relaxation switching (MRS) biosensors have been recognized as useful analytical tools for a range of targets; however, traditional MRS biosensors are limited by the "prozone effect", resulting in a narrow linear range and low sensitivity. Herein, we proposed a paramagnetic Cu2+-induced magnetic resonance tuning (MRET) strategy, based on which Cu2+ ions and magnetic nanoparticles (MNPs) were adopted to construct a Cu–MNP-mediated MRS (Cu–M-MRS) immunosensor with Cu2+ ions acting as a quencher and MNPs as an enhancer. An Fe 3 O 4 @polydopamine-secondary antibody conjugate was prepared and used to correlate the amount of Cu2+ ions to the target concentration through an immunoassay. Based on the immunoreaction, the Cu–M-MRS immunosensor enabled the sensitive detection of chlorpyrifos (0.05 ng/mL, a 77-fold enhancement in sensitivity compared with the traditional MRS immunosensor) and Salmonella (50 CFU/mL). The proposed MRET strategy effectively improved the sensitivity and accuracy of the MRS immunosensor, offering a promising and versatile platform for food safety detection. [ABSTRACT FROM AUTHOR]

In this study, we aimed to elucidate the characteristics of water mobility and distribution in soybean antioxidant peptide powders (SAPPs) using low-field nuclear magnetic resonance (LF-NMR). SAPPs of three different molecular weights (MWs) were exposed to a room temperature environment with a relative humidity of 45%, and the dynamics of water mobility and distribution were monitored by LF-NMR. Results revealed that there were four transverse relaxation time fractions in SAPPs. The major (over 90%) fraction was bound water, and the distribution of water in samples with different MWs was different. The moisture absorption capacity of SAPPs with MWs of less than 1 kDa was the strongest, and all T 2 fractions/water population contents in SAPPs with MWs of 1–3 kDa were the lowest. This study provided an effective real-time monitoring method for water mobility and distribution in SAPPs and may have applications for promoting peptides quality assurance. [ABSTRACT FROM AUTHOR]

This research compared the distribution and mobility of water in the longissimus thoracis muscle of 51 Apulo-Calabrese and 52 crossbred pigs differing in growth performances. The Apulo-Calabrese and crossbreed pigs were fed the same diet and slaughtered at 135 and 155 kg live weight, respectively. Besides meat quality measurement, water status was assessed from transverse relaxation time (T 2) weighted signals registered by Time Domain Nuclear Magnetic Resonance (TD-NMR). A mixed model indicated that Apulo-Calabrese pigs had higher a* (P -value < 0.0001), chroma (P -value < 0.0001) and total intensity (P -value = 0.011) values. A Principal Component Analysis showed that the samples from Apulo-Calabrese had higher scores along Principal Component (PC) 2 (P -value = 4.07 × 10−5) and lower scores along PC3 (P -value = 1.50 × 10−7). However PC2 and PC3 explained a low fraction of the total variance, suggesting that few differences characterize meat quality traits of the two genetic types. • We studied water status and meat quality in Apulo-Calabrese and crossbreed pigs. • Apulo-Calabrese meat had higher percentage of water located outside the myofibrils. • Apulo-Calabrese pigs meat showed higher pH and lower water retention ability. [ABSTRACT FROM AUTHOR]