Discovery, verification, and validation of walnut protein marker peptides using LC-MS approaches

Stability and antioxidant function of Porphyra haitanensis proteins during simulated gastrointestinal digestion: Effects on stress resistance and lifespan extension in Caenorhabditis elegans

Porphyra haitanensis proteins (PHP) are natural proteins with various nutritional and biological values. This study was to analyze the composition, stability, and antioxidant activity of PHP before and after simulation gastrointestinal digestion (SGD). Caenorhabditis elegans was used as the model to investigate the functional activity and potential mechanisms of action of the PHP digestion products (PHPDP). The results showed that PHP contained 16 amino acids and exhibited high thermal stability (up to 80 °C), but dimerization or fragmentation occurred in environments with pH 3 and pH 11. After digestion, PHP released 212 bioactive peptides, which significantly enhanced its antioxidant activity and improved the resistance of C. elegans to heat, oxidative, and ultraviolet stress. Furthermore, PHPDP improved oxidative stress in C. elegans and extended its lifespan by increasing antioxidant enzyme activity and reducing malondialdehyde, lipofuscin, and reactive oxygen species levels. The mechanism of action of PHPDP likely involved regulating the insulin signaling pathway through daf-2/daf-16 and modulating the expression of oxidative stress regulators skn-1 and sod-3, thereby enhancing the organism's stress resistance and extending lifespan. This study demonstrated that P. haitanensis could serve as a reliable protein source in daily life and provided a reference for its development and application as a functional food ingredient.

Comparative analysis of LC-MS/MS and real-time PCR assays for efficient detection of potential allergenic silkworm

The silkworm (Bombyx mori) has long been valued food and feed in East Asia for its abundant nutritional and medicinal attributes, conversely, it can elicit allergic responses in susceptible individuals. Therefore, the development of silkworm detection method is required to avert allergenic incidents. In this study, two methodologies, tandem mass spectrometry (LC-MS/MS) and real-time PCR, were developed to achieve effective silkworm detection. These methods exhibited exceptional sensitivity in identifying silkworm presence in processed foods. Furthermore, model cookies spiked with silkworm were used to validate the sensitivities of LC-MS/MS (0.0005%) and real-time PCR (0.001%). Overall, these techniques were useful for trace silkworm detection in food products; therefore, they may help prevent allergic reactions. To the best of our knowledge, this study represents the first comparison of LC-MS/MS and real-time PCR methods for silkworm detection, marking an important contribution to the field. Data are available from ProteomeXchange under identifier PXD042494.

Advancing High-Throughput MS-Based Protein Quantification: A Case Study on Quantifying 10 Major Food Allergens by LC-MS/MS Using a One-Sample Multipoint External Calibration Curve

The LC-MS-based method has emerged as the preferred approach for quantifying food allergens. However, the preparation of a traditional calibration curve (MSCC) is labor-intensive and error-prone. Here, a sensitive and robust LC-MS/MS method for quantifying 10 major food allergens was developed and validated, where the one-sample multipoint external calibration curve (OSCC) was employed instead of MSCC. By employing the multiple isotopologue reaction monitoring (MIRM) technique with only one spiked level in the blank, OSCC can be effectively established. Results demonstrate that the proposed method exhibits excellent performance in selectivity, sensitivity, accuracy, and precision, comparable to that of the traditional MSCC. Additionally, this strategy allows for isotope sample dilution by monitoring the less abundant MIRM channel. Moreover, the developed method was successfully applied to investigate the contamination of 10 food allergens in commercial food products. With its high throughput and robustness, the MIRM-OSCC-LC-MS/MS methodology has many potential applications, especially in the MS-based protein quantification analysis.