Serine, a major amino acid in meat, reacts with glucose via the Maillard reaction to form substituted pyrazines, which enhance its roasty intensity. The carbon skeleton cleavage and recombination of pyrazines formed in the glucose-serine Maillard reaction and their intermediate changes were elucidated by GC×GC-MS and CAMOLA. The reaction continuously proceeded to yield substituted pyrazines, small-molecule carbonyls, and high-molecular-weight melanoidins during heating. The maximum absorbance of the system was observed at 40 min. Ten substituted pyrazines were identified in the glucose-serine model, whose formation was significantly promoted by heating duration. Most carbonyl compounds, particularly the high-abundance 2-butanone, acetaldehyde, 2-pentanone, and formaldehyde, predominantly originated from glucose pyrolysis. The glucose-derived C1-C4 fragments, especially the C3 fragment, served as the primary skeletons for pyrazines including 2,5-dimethylpyrazine and 2-methyl-3,5-diethylpyrazine, although serine provided auxiliary contributions. Monocarbonyls such as 1-hydroxy-2-butanone, 1,3-dihydroxypropanone, and formaldehyde, together with dicarbonyls including glyoxal and methylglyoxal and their carbonyl derivatives, were key intermediates for pyrazine formation. Aminocarbonyl compounds could be formed from reactions between serine and these carbonyls or carbonyl derivatives, yielding different substituted pyrazines depending on aminocarbonyl structure and binding site. This study provided data support for enhancing roasty intensity via serine-mediated reactions.
This study investigated whether publicly accessible pre-trained Vision–Language Models (VLMs), GPT-5.5 (OpenAI) and Gemini 3.1 Pro (Google), can accurately assess cucumber (Cucumis sativus L.) freshness directly from conventional smartphone images acquired under practical imaging conditions. Cucumbers were stored at 4 °C for 21 days and evaluated on days 0, 4, 11, 17, and 21. Images were captured under controlled, indoor ambient, and outdoor natural lighting, with and without commercial cellophane wrapping. AI-generated freshness scores were validated against a human sensory reference and physicochemical, mechanical, and visual quality attributes, including firmness, weight loss, peduncle thickness, and CIELAB color parameters, together with visible changes in surface condition. Firmness and peduncle thickness decreased significantly during storage, whereas weight loss, yellowness, and other visible signs of quality deterioration increased. Hierarchical cluster and Pearson correlation analyses demonstrated strong associations between VLM predictions, storage progression, and objective quality indicators. Importantly, no statistically significant differences in freshness predictions were detected across the tested lighting conditions and packaging treatments (p > 0.05), although the relatively small sample size limits the interpretation of these findings. External validation and repeated-query analyses further supported consistent model performance across diverse imaging environments. These findings demonstrate that pretrained VLMs can reliably evaluate cucumber freshness from ordinary smartphone images without specialized sensors, handcrafted feature extraction, or model retraining, highlighting their potential as scalable, low-cost tools for postharvest quality monitoring, retail inspection, quality-based dynamic pricing during storage, and food waste reduction throughout fresh produce supply chains.
Increasing evidence of Pseudomonas aeruginosa on fresh plant-based foods raises food safety concerns, particularly under changing environmental conditions. Temperature changes may affect plant microbiota and human pathogen presence on fresh produce. This study investigates the temperature-dependent gene expression of P. aeruginosa PAO1 on oak leaf lettuce as a model system and explores the potential for root internalization by P. aeruginosa PAO1. Therefore, temperature-dependent transcriptomic changes of P. aeruginosa PAO1 were assessed by analyzing differentially expressed genes following plant inoculation and incubation at 18 and 22 °C. Moreover, oak leaf lettuce was cultivated in soil inoculated with P. aeruginosa PAO1_sfGFP_UHH07, and internalization was analyzed using confocal laser scanning microscopy. Transcriptomic analyses showed that a moderate temperature increase shifted bacterial gene expression, with virulence-associated genes upregulated at 22 °C and persistence-associated genes predominating at 18 °C. Results provide preliminary evidence that P. aeruginosa PAO1 may internalize into the roots of oak leaf lettuce, whereas no GFP signal indicative of translocation into the leaves was detected. The findings indicate that temperature changes could influence the transcriptional emphasis on virulence- and persistence-associated genes of P. aeruginosa PAO1 present on oak leaf lettuce and provide a basis for further investigation under more complex environmental conditions.
This review critically evaluates the functional properties of the primary bovine casein fractions (αs1-, αs2-, β- and κ-caseins) that are relevant to food systems, focusing on their physicochemical characteristics. It also considers the genetic variation and post-translational modifications (PTMs) among these fractions, which directly affect their properties and functionalities. The gelation of individual casein fractions is primarily influenced by their isoelectric points (pI) and protein-protein interactions. β-casein has an amphiphilic and flexible structure, contributing to its versatility in terms of foaming and emulsifying capabilities. In contrast, αs1-casein has strong calcium-binding properties, and κ-casein plays an important role in steric stabilization at interfaces, particularly in maintaining micelle stability through its glycosylated C-terminal (caseinmacropeptide, CMP) region. Technological challenges in isolating pure casein fractions may contribute to a significant knowledge gap due to the scarcity of systematic studies using purified fractions; β-casein has been studied more extensively than the other casein fractions. Consequently, comprehensive conclusions about the functionalities of αs1-, αs2-, and κ-caseins remain limited. Furthermore, genetic variants were not consistently reported in studies on isolated casein fractions, despite evidence suggesting that these variants influence functional properties. Emerging technologies like precision fermentation and advanced fractionation techniques are expected to enable more targeted functional applications in casein-based ingredients. Therefore, a systematic characterization of casein genetic variants is crucial for optimizing their application in tailored dairy product formulation. Further research in real food matrices, such as dairy systems, is necessary to accurately assess and optimize the techno-functional properties of individual casein fractions.
Protein interfacial adsorption is fundamental to the formation and stabilization of emulsions. However, the limited interfacial adsorption performance of brown rice protein isolate (BRPI) restricts its application as a plant-based emulsifier. This study investigated how germination modifies BRPI structure and how these changes relate to interfacial adsorption, film mechanics, and emulsifying performance. Untreated, soaked, and germinated BRPI were compared through structural characterization, interfacial adsorption kinetics, dilatational rheology, and emulsion evaluation. Soaking alone induced slight aggregation and reduced emulsifying activity, whereas subsequent germination promoted partial protein hydrolysis and conformational loosening, accompanied by smaller particle sizes and increased solubility, conformational flexibility, and surface hydrophobicity. These changes were associated with faster interfacial adsorption and the formation of stronger, elasticity-dominated interfacial films. Among the investigated treatments, 24 h germination yielded the highest emulsifying activity index and emulsifying stability index, increasing from 2.61 to 4.49 m2/g and from 39.15 to 191.49 min, respectively, compared with untreated BRPI, and produced finer, more uniformly dispersed emulsion droplets. Correlation analysis showed that both emulsifying indices were positively associated with diffusion, penetration, and rearrangement rate constants, interfacial dilatational elastic modulus, and the E–π slope. These findings support a mechanism in which germination-induced structural remodeling improves protein adsorption and interfacial film elasticity, jointly facilitating emulsion formation and stabilization. Controlled germination therefore represents a promising strategy for enhancing the functionality of BRPI as a plant-based functional emulsifier.
