Passion fruit readily develops chilling injury (CI) when stored at low temperatures, which severely limits its storability and marketability. γ-aminobutyric acid (GABA) has been increasingly recognized for its ability to improve stress tolerance in horticultural products. Accordingly, this work investigated the role of GABA in alleviating CI in passion fruit through modulation of proline, polyamine, and GABA metabolisms. Fruit treated with 6 mmol/L GABA for 15 min prior to cold storage (5 °C) showed substantially lower chilling injury severity, with the CI index reduced by 48.28% compared with untreated fruit at 35 d. This was accompanied by a lower respiration rate, reduced a* and b* values, a slower cell membrane permeability (CMP) and MDA content increase. GABA treatment also maintained higher transcript levels of PeARG1, PeDELTA-OAT, and PeP5CS and increased ARG, OAT, and P5CS activities, thereby maintaining higher arginine and ornithine levels and promoting proline accumulation in passion fruit. Additionally, GABA enhanced ODC and ADC activities, resulting in higher PAs (Spm, Spd, and Put) contents. Moreover, GABA treatment promoted GABA accumulation by maintaining higher transcript levels of PePAO and PeGAD genes, elevating DAO and PAO activities, maintaining higher GAD activity, and inhibiting GABA-T activity. These metabolic alterations helped maintain cell membrane integrity, suppress excessive respiration, and enhance chilling tolerance. Taken together, the GABA treatment-enhanced storability of passion fruit was associated with its regulatory role in proline, polyamine, and GABA metabolism, which strengthened chilling tolerance and reduced CI occurrence during storage.

The encapsulation of plant-based materials, particularly in emulsion systems, is gaining attention for enhancing the texture, digestibility, and health benefits of food products. However, the impact of interactions between plant proteins, such as pea protein isolate (PPI), and polysaccharides, like peach gum (PG), on the rheological properties, digestion, and absorption behaviors of emulsions is leaving a gap for further investigation. This study investigates the formulation of four 20 wt% oil-in-water (O/W) emulsions: PPI emulsion (4 wt% PPI), PG emulsion (4 wt% PG), PPI-PG emulsion (2 wt% each in aqueous phase), and a 1:1 mixture of individually prepared PPI and PG emulsions (PPI/PG). The emulsions underwent thermal processing to induce particle aggregation and heteroaggregation, followed by in vitro digestion and ex vivo absorption using a rat small intestine model. The mixed emulsions exhibited significantly higher viscosities and moduli than single emulsions, along with larger and denser microstructures. Consequently, free fatty acids (FFAs) released at the end of digestion were lowest for PPI-PG (33.7 %), followed by PPI (44.92 %), PG (39.93 %), and PPI/PG (36.32 %). Correspondingly, ex vivo FFA absorption was slower for PPI-PG (9.83 %) and PPI/PG (10.81 %) than for PG (14.95 %) and PPI (16.33 %), reflecting reduced enzyme accessibility due to stronger interfacial structures. These findings highlight the potential of PPI-PG and PPI/PG emulsions in creating reduced-fat O/W products, such as mayonnaise and sauces, with higher viscosity but controlled lipid digestion.

Traditional static in vitro digestion models neglect the critical role of oral processing, leading to poor physiological relevance, particularly for vulnerable populations such as older adults with impaired chewing function. Here, we present a closed-loop system that couples a bio-inspired oral mastication simulator (iBOMS-III) with a dynamic human stomach-intestine system (DHSI-IV), replicating the complete sequence of mechanical chewing, bolus formation, gastric emptying, and intestinal digestion under physiologically relevant conditions. Using egg white gels (EWG) cooked at 75 °C (soft, 75-EWG) and 95 °C (firm, 95-EWG) as model protein foods, we simulated declining masticatory capacity in the elderly with 3D-printed dental molds representing intact dentition (M0T), loss of 3 teeth (M3T), and loss of 6 teeth (M6T). Progressive tooth loss dramatically reduced masticatory performance: median bolus particle size (d₅₀) increased from 1.40 mm (M0T) to 2.05 mm (M3T) for 75-EWG and from 2.13 mm to 2.67 mm for 95-EWG. This larger particle size directly delayed gastric emptying (dry-matter half-time t₁/₂ lengthened from 105 to 117 min for 75-EWG and from 147 to 169 min for 95-EWG) and significantly lowered terminal small-intestinal protein hydrolysis after 3 h of digestion, with free amino acid release dropping from 50.1 to 39.9 mg/g (75-EWG) and from 40.6 to 29.8 mg/g (95-EWG). These findings demonstrate that both impaired mastication due to tooth loss and increased food hardness synergistically hinder bolus breakdown, delay gastric transit, and reduce protein hydrolysis in the elderly. The integrated iBOMS-III/DHSI-IV platform represents a promising in vitro tool that reliably replicates the entire upper gastrointestinal process, offering unprecedented physiological fidelity for designing texture-modified, digestion-friendly foods tailored to older adults.

The unpredictable wettability of pharmaceutical microparticles, often stemming from complex phase transitions during processing, frequently eludes conventional unidimensional assessments of surface hydrophilicity. In this study, mannitol-leucine microparticles were fabricated via spray drying and spray freeze drying. Their structural properties-including morphology, particle size, and polymorphism-were systematically correlated with surface energetics (dispersive energy, acid-base characteristics, and hydrophilic site distribution) as delineated by inverse gas chromatography (IGC). Increasing leucine content induced pronounced surface wrinkling, sustained crystalline stability, and resulted in larger particle sizes in spray-dried samples. Conversely, spray-freeze-dried particles maintained a relatively uniform morphology but exhibited unstable δ-mannitol polymorphs with enhanced dispersibility. IGC analysis uncovered that leucine enrichment elevated dispersive surface energy, attenuated surface basicity, and diminished the hydrophilic surface area, with these effects being more pronounced in the spray-dried samples. Crucially, both the absolute hydrophilic surface area and the fractional distribution of hydrophilic domains were identified as key determinants modulating particle wettability and release behavior. This study highlights the capacity of IGC to resolve multiparametric surface energetics, thereby advancing the mechanistic understanding of pharmaceutical particle wettability through non-invasive, high-precision characterization.

High-moisture extrusion is the most cost-effective method for producing meat analogues with desired microstructure and textural characteristics, owing to its combined unit operations and customisable process conditions. An appropriate combination of extrusion conditions is crucial for obtaining high-moisture meat analogue (HMMA) products with the desired characteristics. In this study, we systematically investigated the effects of varying extrusion conditions, specifically temperature (130-160 degrees C) and screw speed (100-300 rpm), on the formation of fibrous structure of faba bean protein-based HMMA in the presence of brewers' spent grain. Our findings indicate that higher screw speeds and temperatures significantly enhanced the phase separation, physical cross-linking, and fibrous structure formation, which improved textural attributes and increased water retention capacity. Importantly, the fibrous structure achieved through adjusting extrusion conditions did not adversely affect the digestibility of faba bean protein-based HMMA. By reporting the efficacy of the extrusion conditions in structuring fibrous meat analogues similar to chicken meat, this study demonstrates that a highquality meat alternative product can be efficiently produced using two sustainable ingredients (faba bean protein and brewers' spent grain) without any external modifiers.

Coral, as a bioreactor, has to continuously interact with surrounding environment to maintain a healthy state. A multi-physics reaction engineering model has been developed to capture this interaction. The coral interior is modeled as interconnected reaction units respectively for photosynthesis, respiration, and calcification, whose reaction kinetics are influenced by environmental fluctuations. Coupling between coral and environment is realized by bi-directional mass transfer at the coral-seawater interface, with consideration of the unique flow fields induced by ciliary beating. By resorting to this comprehensive model, we discover that ciliary beating demonstrates distinctively different diurnal and nocturnal functions. During daytime, beating can help reduce photosynthetic oxygen accumulation to prevent hyperoxia-induced mortality, while enhancing carbon dioxide uptake efficiency to promote nutrient production. At night, however, beating promotes oxygen acquisition for adequate respiration, while expelling carbon dioxide to inhibit symbiotic destruction under acidic stress. The model further enables mechanistic analysis of the detrimental impact of climate change on coral health, where the influences from two key factors (i.e., temperature and CO2 level) can be decoupled. It's interesting to find out that the elevated temperature plays a dominant role during daytime, while at night the coral is dominantly influenced by rising CO2 level. ### Competing Interest Statement The authors have declared no competing interest. National Natural Science Foundation of China, 21978184

For many scientists and technologists including students, rigorous engineering principles are harder to grass due to the generally higher mathematics required. Here it is demonstrated that it is feasible to generate a 'complex' mathematical engineering model through largely descriptive expressions (i.e. by talking), gradually leading the students to make progress. Putting the known parameters (talked about it one by one intuitively) gradually into groups of formulas with little fear and see where one may get to end up with a final model. As an example, freeze-drying of a porous solid matrix has been 'talked about', 'muscling' all those concerned into good enough mathematical result(s) that correlates well the moisture loss over time which is often the prime objective in freeze-drying modeling. It is shown to be possible to find more examples in future that can be 'talked through' for easier understanding by the students.

Two-dimensional (2D) computational fluid dynamics (CFD) models have been conventionally adopted for simulating a wide range of fluid flow problems. It is especially useful when the fluid-flow domain is almost 2D, has perfect symmetry (e.g., axial symmetry), or the 3D geometry is too complex and hence too computationally demanding. For the last case, the difference between the "realistic" 3D geometry of the system under investigation and the "surrogate" 3D geometry represented by a 2D model should be fully appreciated in order to rationally predict fluid flow behavior. This article aims at the development of a surrogate 2D CFD model for reliable prediction of gastric emptying, which is critical for understanding the digestion process. The motivation for such development is first justified by the significant overestimation of emptying rate by a conventional 2D model. Respecting the difference between the 3D realistic and surrogate geometries, to achieve equivalent emptying rate, we then develop a mapping approach that can convert measured dynamic data on pyloric diameter to pyloric size evolution in the 2D model. This surrogate model not only has high computational efficiency due to its 2D nature but also achieves emptying rate that is very close to the 3D model. At the same time, it can capture 3D flow behavior, such as retropulsive flow and recirculation eddies. Furthermore, the model demonstrates excellent generality for fluids with different properties, offering a powerful tool for gastric emptying studies.

The digestibility and protein quality of soft-textured foods are fundamental to ensuring adequate protein intake and overall nutritional status in older individuals. This study investigated the digestion behaviour of custard-type soft foods formulated with milk protein concentrate (MPC), soy protein isolate (SPI), and their blends, prepared with or without transglutaminase. A dynamic human stomach-intestine model designed to closely mimic digestion in the elderly, was used to conduct in vitro digestion tests. Gastric emptying rate, particle size, zeta potential, elastic modulus, protein hydrolysis, free amino acid profile, and in vitro Digestible Indispensable Amino Acid Score (DIAAS) were measured to assess protein quality and digestibility. Custards based on MPC showed superior digestibility, with smaller particle sizes, fewer aggregates, and greater protein hydrolysis after 180 min of digestion. In contrast, SPI-based custards exhibited larger particles, higher aggregation, and lower digestibility. A faster gastric emptying rate was observed in the MPC-based custards, corresponding to a shorter half-disintegration time (t1/2) (46.08 min) compared to SPI (50.29 min) and MPC-SPI blends (56.57 min). Micro-texture profile analysis revealed that gastric digestion led to increased firmness and elastic modulus in all samples due to protein coagulation prior to transition into the intestinal phase. Threonine was identified as the limiting amino acid across all samples based on amino acid profiling and in vitro DIAAS calculations. These findings highlight the nuanced considerations required when selecting protein sources and underscore the importance of assessing digestion kinetics and amino acid bioavailability in the development of protein-rich soft foods for older individuals, particularly those with swallowing difficulties.

In industrial processes, mixing high-viscosity fluids at low Reynolds number remains a challenge for traditional mechanical stirring methods. This study introduces a novel bionic small intestine circular flow peristaltic reactor (BSCPR) inspired by the mammalian digestive system. Its mixing performance was investigated through experiments and numerical simulations. Results show that the BSCPR can achieve efficient shear-free mixing of high-viscosity fluids at low Reynolds numbers with much lower energy cost than mechanical stirring. The presence of villi and fold structures on the inner wall significantly enhances mixing. The peristalsis amplitude, velocity, and displacement all affect mixing. Both experimental and simulation results demonstrate that during the process of mixing high viscosity fluids, by tuning the peristalsis velocity or displacement to maintain the Reynolds number above 10 with a peristalsis amplitude of 75%, highly efficient mixing can still be attained. Overall, the BSCPR shows great potential in industries requiring shear-free mixing of high viscosity fluids.

Probiotics such as Lactobacillus and Bifidobacterium are essential for infant gut health, yet their digestive stability and post-gastrointestinal regrowth remain poorly understood. This study evaluated the survival and post-digestive regrowth of three commercial probiotic powders under simulated infant gastrointestinal conditions using the Dynamic Infant Stomach (DIS-II) model. Both fasted (water) and fed (milk) states were examined to represent physiologically relevant feeding conditions. Simulated gastric and intestinal digestion were followed by static colonic fermentation to assess bacterial viability and recovery. Results showed that milk significantly delayed gastric emptying and improved bacterial survival compared with fasting. Moreover, milk feeding markedly enhanced post-digestive regrowth of Lactobacillus, whereas Bifidobacterium recovery remained strain- and condition-dependent. These findings demonstrate that both the feeding matrix and probiotic composition critically influence digestive resilience and post-digestive functionality, providing preclinical evidence for the use of milk-based carriers to enhance probiotic performance in infant formulations.

Polysaccharide-based hydrogels for gastric retention face the inherent challenge of achieving effective retention through swelling while avoiding mechanical failure. Here, we introduce a strategy by incorporating curdlan into chitosan/sodium polyacrylate interpenetrating networks to reinforce the hydrogel and regulate swelling-induced transport behavior. Curdlan-reinforced chitosan/polyacrylate (CS/CUR/PAAS) hydrogels with varying curdlan content (0-4 wt.%) were synthesized and characterized. Optimal reinforcement was achieved with 2 wt.% curdlan, yielding an indentation hardness of ~80 kPa and an elastic modulus of ~63 kPa without compromising swelling capacity. Under acidic conditions (pH 1.2), the hydrogel swelled rapidly (~50-fold at 3 h; ~140-fold at 8 h) while maintaining structural integrity. Using a dynamic in vitro human stomach simulator (DHSI-IV), the optimized hydrogel demonstrated gastric retention for up to 5 h, with ~60% of the initial mass retained at 6 h. Metformin hydrochloride release followed diffusion-controlled kinetics (~69% over 8 h), governed primarily by pH with secondary shear modulation. Microstructural and rheological analyses revealed that acidic conditions regulated network expansion, viscoelastic relaxation, and pore formation, which in turn controlled transport pathways and drug release. The findings highlight that curdlan reinforcement stabilizes swelling behavior under acidic conditions, offering a robust and pH-responsive strategy for designing mechanically stable, gastric-retentive hydrogels.

Understanding how digestion-derived nutrients influence probiotic and pathogen behavior is essential for designing functional foods and microbiome-targeted formulations. This study developed a dynamic in vitro fermentation platform to quantify how milk digestion products and substrate composition regulate the growth and metabolism of Lacticaseibacillus rhamnosus GG (LGG), Bifidobacterium animalis subsp. lactis BB-12 (BB-12), and Escherichia coli (E. coli). Digestates from human milk (HM), infant formula (IF), and a defined control milk (CM) were fermented under batch and semi-continuous conditions. Compared with static batch culture, semicontinuous fermentation increased probiotic viability by up to 5.8 log CFU/mL and reduced E. coli by approximately 1.0 log CFU/mL, demonstrating that dynamic nutrient exchange enhances ecological stability. Glucoseenriched media (CBM-G) rapidly produced lactic and acetic acids, driving competitive exclusion of E. coli, whereas lactose-based media (CBM-L) slowed acidification but sustained probiotic metabolism through gradual carbohydrate hydrolysis. The mucin-tryptone-glucose formulation (CBM-MTG) generated the most metabolically diverse environment, enriched in bile acid derivatives, peptides, and flavonoid glycosides, which correlated with improved metabolic resilience. These results highlight that fermentation mode and substrate complexity synergistically determine microbial competition, metabolic pathways, and functional metabolite production. The developed platform provides an engineering framework to predict nutrient-microbe interactions and guide substrate optimization for next-generation probiotic formulations and infant nutrition research.

Elbow wear and particle deposition issues frequently pose significant challenges in multiphase pipeline transportation systems. To this end, this paper proposes installing a swirl-type flow deflector vane device upstream of the elbow, aiming to alter the particle flow pattern through swirling motion and thereby reduce sedimentation and erosion damage. For two-phase flow problems involving coarse particles, a semi-resolved CFD-DEM model is proposed. By employing a piecewise cubic kernel function with strictly normalized characteristics to reconstruct background information, it bridges the simulation gap between resolved and unresolved CFD-DEM methods. The present study focuses on analyzing particle flow behavior and wall wear characteristics with and without deflector vane-type swirler. The findings indicate that after installing the deflector vane, the fluid flow generates a tangential component that increasing the swirl intensity, which then exhibits a consistent decay trend along the flow direction. The presence of deflector vane transforms the uneven distribution of particles into an orderly and uniform spiral structure. It enhances the suspension rate of particles near the outlet of the horizontal pipe section. Additionally, the most severely worn area of the elbow also shifts, with the wear hotspot moving from the circumferential angle phi = 0-30 degrees to phi = 45 degrees-75 degrees When the inlet velocity was increased from 5 m/s to 7 m/s, the maximum dimensionless wear rate decreased respectively by 31.10% and 13.66% in the first two cases, while it increased by 2.48% in the third case. This indicates that when the inlet velocity increases to a certain extent, the maximum wear rate with vane becomes higher than that without vane. Consequently, a reasonable balance must be identified between flow velocity and wear control.

Flavor release during oral processing is strongly influenced by oral physiological variability, yet the individual roles of mastication parameters are difficult to isolate in vivo. This study examined how bite force and saliva flow rate affect bolus formation and polarity-dependent aroma release in semi-hard Cheddar and soft goat cheese. Using a bio-inspired oral mastication system (iBOMS-III), bite force (250 or 500 N) and saliva flow (2.0 or 2.4 mL/min) were controlled to investigate their effects on bolus properties and volatile compound release. Saliva incorporation contributed to bolus hydration during mastication, while increased bite force and saliva flow were associated with substantial bolus softening, reducing hardness from 50.7 kPa (Cheddar) and 42.4 kPa (goat cheese) to 5.2 and 2.8 kPa, respectively. At constant saliva flow (2.0 mL/min), increasing bite force enhanced the release of volatile compounds from Cheddar boluses, reaching 60.8 μg/mL acetic acid, 23.5 μg/mL butanoic acid, 20.3 μg/mL hexanoic acid, and 10.4 μg/mL octanoic acid. Conversely, increasing saliva flow at 250 N selectively reduced hydrophilic acetic and butanoic acids (from 54.6 to 49.2 μg/mL and 21.6 to 19.3 μg/mL, respectively), consistent with aqueous dilution, whereas hydrophobic compounds remained largely unaffected. Goat cheese released higher levels of aroma than Cheddar under equivalent conditions, likely due to differences in matrix composition and volatile retention. These findings highlight the distinct roles of bite force and saliva flow rate in shaping bolus transformation and aroma release, offering insights for targeted flavor design in cheese and other solid foods.

Optimizing nutritional strategies for the elderly requires a deep understanding of how food structure influences digestive behavior. This study explored the effects of dietary fiber fortification on milk digestion under simulated elderly gastrointestinal conditions (characterized by reduced gastric acidity, lower digestive enzyme activity, and slower motility), with a particular focus on the formation and properties of gastric clots and their impact on protein hydrolysis kinetics. Milk was fortified with polydextrose (PD), sodium alginate (SA), hydroxypropyl trimethyl ammonium chloride chitosan (HACC), or wheat bran (WB) at 10 mg/mL, and subjected to in vitro digestion modeling. The results demonstrated that dietary fibers significantly altered clot characteristics, such as mass, rigidity, and viscosity, thereby modulating enzymatic accessibility and digestion efficiency. HACC-Milk and WB-Milk formed larger, denser clots with increased mechanical strength and viscosity, resulting in reduced degrees of hydrolysis (26.15 f 1.23 % and 24.55 f 1.05 %, respectively) compared to control milk (30.31 f 1.90 %) by the end of intestinal digestion. In contrast, SA-Milk and PD-Milk generated softer, more fragmented clots, enhancing enzyme diffusion and yielding significantly higher hydrolysis levels (35.33 f 1.43 % and 32.60 f 1.06 %, respectively). Rheological and textural analyses confirmed that WB and HACC reinforced clot structure and hindered proteolysis, while SA and PD attenuated clot formation, promoting protein breakdown. These findings highlight the pivotal role of gastric clots in modulating protein digestion kinetics and provide insights for designing fiber-enriched dairy formulations tailored to the elderly.

As a natural flavonoid compound, quercetin possesses excellent antioxidant, anti-inflammatory and anti-atherosclerotic activities. However, the poor water solubility and sensitivity to the environment severely limit the application of quercetin. Initially, quercetin-loaded zein/carboxymethyl chitosan nanoparticles (ZCQ NPs) were prepared using an anti-solvent precipitation method. The fabricated ZCQ NPs exhibited a small particle size and polydispersity index (PDI). The ZCQ NPs had a negative zeta potential with an absolute value of 41.50 ± 1.76 mV. ZCQ NPs could remain highly stable against light, heat and ion strength. In addition, ZCQ NPs maintained good monodispersity and displayed minimal changes in particle size under long-term storage conditions. Additionally, a superior antioxidant capacity of ZCQ NPs was also observed in the free radical and reactive oxygen species (ROS) scavenging study compared to that of free quercetin. All these results of this study suggest that ZCQ NPs could serve as an effective drug delivery system for encapsulating and delivering quercetin.

Producing probiotic powders with high viability and low moisture content using conventional single-stage spray drying is challenging due to the harsh drying environment. A two-stage drying process integrating spray drying and fluidized-bed drying is known as a good strategy by enabling further moisture removal under moderate conditions. It may reduce excessive thermal exposure for preserving viability. However, the effects of dryer design and operating conditions on particle drying behavior and probiotic survival at pilot scale or above remain less understood. Here, a pilot-scale two-stage dryer (4.25 kg/h) for producing Lactobacillus rhamnosus GG (LGG) powders was investigated using a Euler-Lagrangian framework coupled with drying and LGG inactivation kinetics. The effects of dryer geometry, outlet location, operating conditions, droplet size distribution, and fluidized-bed hydrodynamics on particle moisture content, LGG viability, and wall deposition were evaluated. The results showed that two-stage drying can improve LGG viability by approximately 15% compared with conventional single-stage under identical inlet and conditions. Thermal and humidity conditions were the dominant factors, while geometric parameters mainly affected particle transport and deposition. The tapered fluidized-bed configuration reduced wall deposition and improved drying performance, although its longer particle residence time increased thermal exposure. Smaller droplets enhanced drying efficiency but reduced LGG viability due to faster moisture removal and higher particle temperatures, whereas airflow-related parameters mainly influenced deposition rather than final product properties. This study provides insights into the optimization of pilot-scale two-stage drying systems and demonstrates the value of numerical experiments for evaluating complex multiphase drying processes.

The efficient transport of luminal contents in the small intestine is governed by a closed-loop control system linking sensory feedback (the sensor block), neural regulation (the controller block), muscular actuation (the actuator block) and fluid-structure interaction (the process block). Existing computational studies have typically addressed isolated blocks of this loop, such as fluid dynamics under prescribed motor patterns, offering limited system-level insights. Here, we present CREST (Closed-loop REgulation of Small intestinal Transport), an integrated mechano-physiological control framework for simulating small intestinal transport. CREST couples a mechanical module, which captures wall-deformation-driven fluid flow under muscle contractile force, with a physiological module, which senses strain, compares it to a reference strain and activates smooth muscle contraction via the enteric nervous system. Through this closed-loop interaction, CREST reproduced clustered peristaltic waves with amplitudes and velocities consistent with experimental observations, and revealed interesting transport phenomena that align with ex vivo data. By closing the feedback loop, CREST provides a powerful computational framework for system-level exploration of intestinal functions, laying the foundation for the digital intestine twin and bioinspired control strategies.