Development in Maillard Reaction and Dehydroalanine Pathway Markers during Storage of UHT Milk Representing Differences in Casein Micelle Size and Sedimentation

Optimization of liquid chromatography and mass spectrometry parameters based on LC-QQQ: A case study on lysinoalanine

Lysinoalanine (LAL), commonly formed in high-protein foods, raises concerns due to its nephrotoxicity and potential reduction in nutritional properties, making its accurate detection crucial for food safety. Liquid chromatography-tandem quadrupole mass spectrometry (LC-QQQ) plays a pivotal role in the quantification of compounds, and its accuracy and sensitivity are significantly influenced by specific liquid chromatography (LC) and mass spectrometry (MS) parameters. However, the procedure and considerations for LC and MS parameters optimization have often not been discussed in depth in existing literature. Therefore, this study used LAL as a model compound to systematically optimize the key LC and MS parameters using LC-QQQ. The optimized MS parameters were as follows: parent ion m/z-234.2, capillary voltage-3.5 kV, cone voltage-30 V, desolvation temperature-500 °C, daughter ion m/z-84.2, and collision voltage-20 V. The optimized LC parameters were as follows: buffer-0.1 % formic acid (v/v), column, Polaris 3 Amide-C18 (150 × 3 mm, 3 μm). Under these optimized conditions, the limit of detection (LOD) for LAL was detected as 13 ng/mL in multiple reaction monitoring mode, which is considerably lower than the 125 ng/mL detected by LC-QQQ and marginally lower than the 15.23 ng/mL detected by LC-quadrupole Exactive Orbitrap MS reported in previous studies. Additionally, this study elucidates the critical factors to be considered when selecting LC and MS parameters, providing valuable insights into the detection of other compounds using LC-QQQ.

Storage stability and shelf-life of soymilk obtained via repeated boiling and filtering: A predictive model

This study investigated the effects of different processing methods on the quality and nutrition of soymilk, as well as the changes in storage stability (centrifugal sedimentation rate (CSR), viscosity, and particle size) and shelf-life of soymilk at different storage temperatures (25°C, 35°C, 45°C, and 55°C). Results showed that soymilk processed via the repeated boiling-to-filtering method (RBFM) exhibited the highest protein content (3.89 g/100 g), carbohydrate content (1.27 g/100 g), and stability coefficient (0.950). The CSR and particle size of RBFM soymilk increased gradually during storage at different temperatures, while the viscosity and sensory score decreased. The correlation between the CSR and the sensory score of RBFM soymilk was the highest (R 2 = .9868). The CSR was selected as the key indicator to predict the shelf-life of RBFM soymilk. The average residual variation in RBFM soymilk shelf-life based on the predictive model was 10.78%, indicating the strong accuracy of the model for predicting the shelf-life of RBFM soymilk stored at temperatures ranging from 25-45°C. This study provides a theoretical basis and technological support for the development, transportation, and storage of soymilk and soymilk beverage products.

Storage Stability of Plant-Based Drinks Related to Proteolysis and Generation of Free Amino Acids

The market for plant-based drinks (PBDs) is experiencing a surge in consumer demand, especially in Western societies. PBDs are a highly processed food product, and little is known about this relatively new food product category when compared to bovine milk. In the present study, the storage stability, proteolysis and generation of free amino acids were investigated in commercially available PBDs over the course of a one-year storage period. Generally, pH, color and protein solubility were found to be stable in the PBDs during storage, except for the pea-based product, which showed less protein solubility after storage. The pea-based drinks also had higher initial levels of free N-terminals prior to storage compared with levels for the other plant-based drinks, as well as significantly increasing levels of total free, and especially bitter free, amino acids. The development of free amino acids in the oat-based drink indicated that the released amino acids could be involved in various reactions such as the Maillard reaction during the storage period.

Processing-Induced Markers in Proteins of Commercial Plant-Based Drinks in Relation to Compositional Aspects

The consumption of plant-based drinks is increasing, but they represent a product category normally with lower protein content as compared with bovine milk. Furthermore, the products are highly processed and, therefore, the proteins in this product category may carry a significant processing history. In the present study, a series of 17 freshly produced, commercially available plant-based drinks were benchmarked according to protein-quality parameters. The plant-based drinks represented different plant sources, as well as some mixed products, and were investigated relative to composition, aggregate sizes, presence of non-reducible proteins complexes, and level of processing-induced markers in the proteins. Processing-induced changes in the proteins were determined by a newly developed cocktail method, determining markers related to Maillard and dehydroalanine pathways, as well as intact lysine by triple quadrupole-multiple reaction monitoring-mass spectrometry. It was found that all drinks contained non-reducible protein complexes, but specifically, oat-based drinks represented the largest span contents of processing-induced markers within the proteins, which may relate to their inherent processing histories. Furthermore, it was shown that in products containing added sugar, Maillard reaction-related processing markers were increased over the dehydroalanine pathway.

Response Surface Optimization of Solar Drying Conditions and the Effect on the Quality Attributes and Drying Characteristics of Qula Casein

The objective of this study was to investigate the potential application of a mixed-mode solar dryer to Qula dehydration in the Qinghai-Tibet Plateau of China. A three-factor five-level central composite rotatable design (CCD) of the response surface methodology (RSM) was employed to evaluate the influences of drying process variables on quality attributes in terms of lipid oxidation [peroxide (POV) and thiobarbituric acid reactive substance (TBARS)] and Maillard reaction (5-hydroxymethylfurfural, 5-HMF). The impact of drying temperature (30−50 °C), material thickness (5−15 mm), and wind velocity (0.4−1.4 m/s) on the color, POV, TBARS, and 5-HMF of Qula were studied. Optimum operating conditions were found to be a temperature of 43.0 °C, material thickness of 11.0 mm, and wind velocity of 1.0 m/s based on the minimum of POV, TBARS, and 5-HMF. In this condition, the values of POV, TBARS, and 5-HMF were 0.65 meq/kg, 0.516 mg/kg, and 4.586 mg water/L, respectively, which are significantly lower than for drying of Qula by open sun-drying (p < 0.05). Compared with open sun-drying, the drying time of Qula by solar drying was shortened by 61.5%. The results indicate that the mixed-mode solar dryer is a feasibility drying technology for Qula and could effectively improve the quality of products.