RESUMEN
The digestion of starch-based foods in the intestinal tract is important for human health. Modeling the details enhances fundamental understanding and glycemic prediction accuracy. It is, however, a challenge to take granular properties into account. A multiscale digestion model has been proposed to characterize mass transfer and hydrolysis reaction at both the intestine and particle scales, seamlessly integrating inter-scale mass exchange. A specific grid scheme was formulated for the shrinkage and transport of the particle computational domain. By incorporating additional glycemic-related processes, e.g., intestinal absorption, a dietary property-based glycemic prediction system has been developed. Its effectiveness was validated based on a human tolerance experiment of cooked rice particles. The model-based investigation comprehensively reveals the impact of initial size on digestion behavior, specifically in terms of enzyme distribution and particle evolution. This work also demonstrates the significance of modeling both particle-scale diffusion and intestine-scale transport, a combination not previously explored. The results indicate that ignoring the former mechanism leads to an overestimation of the glycemic peak by at least 50.8%, while ignoring the latter results in an underestimation of 16.3%.
Asunto(s)
Digestión , Modelos Biológicos , Almidón , Almidón/química , Almidón/metabolismo , Humanos , Oryza/química , Índice Glucémico , Tamaño de la Partícula , Hidrólisis , Absorción IntestinalRESUMEN
Mesoporous aluminosilicates Al-SBA-15 with large pore sizes and suitable acid properties are promising substitutes to zeolites for catalytic cracking of bulky hydrocarbons without molecular diffusion limitation. The conventional processes to synthesize Al-SBA-15 are time-consuming and often suffer from low "framework" Al contents. Herein, Al-SBA-15 microspheres are synthesized using the rapid and scalable microfluidic jet spray drying technique. They possess uniform particle sizes (45-60 µm), variable surface morphologies, high surface areas (264-340 m2/g), uniform mesopores (3.8-4.9 nm) and rich acid sites (126-812 µmol/g) and high acid strength. Their physicochemical properties are compared with the counterparts synthesized using traditional hydrothermal and evaporation-induced self-assembly methods. The spray drying technique results in a higher incorporation of aluminum (Al) atoms into the silica "framework" compared to the other two methods. The catalytic cracking efficiencies of 1,3,5-triisopropylbenzene (TIPB) on the Al-SBA-15 materials synthesized using the three different methods and nanosized ZSM-5 are compared. The optimal spray-dried Al-SBA-15 exhibits the best performance with 100 % TIPB conversion, excellent selectivity (about 75 %) towards the formation of deeply cracked products (benzene and propylene) and high stability. The catalytic performances of the spray-dried Al-SBA-15 with varying Si/Al ratios are also compared. The reasons for the different performances of the different materials are discussed, where the mesopores, high acid density and strength are observed to play the most critical role. This work might provide a basis for the synthesis of mesoporous rich metal-substituted silica materials for different catalytic applications.
RESUMEN
This study aimed to evaluate gastric emptying and enzymatic hydrolysis of skim milk using a dynamic in vitro gastrointestinal system mimicking digestive conditions in young adult and elderly individuals. The gastric emptying half-time was 22.5 and 26.5 min in the young adult and elderly models, respectively. The degree of proteolysis at 120 min reached 42.3 % under adult digestion, significantly higher than that for the elderly (37.2 %). Moreover, milk proteins, particularly ß-lactoglobulin, was more resistant to hydrolysis throughout elderly digestion. The slowed gastric emptying and impaired proteolysis were supported by the formation of more large clusters and protein aggregates under elderly digestion particularly between 60 and 120 min. This was attributed to the decreased gastric contractions and lowered digestive secretions in the elderly model that would impede the flow and breakdown of protein aggregates. This study is meaningful for future development of milk products that are more suitable for the elderly.