| In vitro biomimetic digestive system that simulates the human or animal gastrointestinal tract has been broadly applied as a "pre-screening" tool to carry out relevant scientific experimental research and assist in understanding mixing,digestion and gastric emptying phenomenon in the digestive tract.Compared with the in vivo experiments,in vitro trials are easily operated,less labor and time-consuming,cost-saving and relatively reproducible without ethical restrictions involved in vivo.Thus,a series of in vitro digestion models have been widely used so far in food nutrition,environmental toxicology and pharmacology.Previously,our team has developed a rope-driven dynamic in vitro human stomach system(RD-?-HSM),of which a silicone human stomach model with similar morphology,dimensions and inner wrinkles to the actual human stomach was created manually based on the principle of anatomical bionics.The RD-?-HSM was validated by showing consistent trends of gastric distribution and emptying of cooked buckwheat with that in vivo data reported in literature.However,some drawbacks existed:it has limited grinding capacity on the particles due to the weak contraction force produced by the rope-driven device;the gastric emptying rate was rather difficultly controlled;the fabrication of the silicone stomach model was time and labor-consuming with poor repeatability and higher cost.Hence,the research contents and main conclusions of the current dissertation include1)The effect of the motion parameters of the DIVHS on the gastric emptying behavior of single liquid and solid was investigated.The results showed that the gastric emptying rates of the liquid and solid fractions were significantly affected by the tilting angle of the whole stomach system.The simulated stomach system was able to generate consistent gastric emptying ratios of both the solid and liquid fractions in the beef stew mixed with orange juice(150 g beef stew and 150 g orange juice)with that reported in vivo(p>0.05).By fitting the gastric retention data with a modified power-exponential model,the solid fractions showed the average emptying rate(k),emptying half-time(t1/2)and lag phase(tlag)of 0.0154 L/min,74.1 min and 36.3 min in the DIVHS,respectively,similar to that obtained in vivo where the average values of k,t1/2 and tlag were 0.0149 L/min,75.8 min and 40.2 min,respectively.The liquid fractions in the mixed meal presented similar emptying features with that in vivo.2)The gastric digestion and emptying characteristics of cooked rice and noodles were evaluated with the DIVHS.The results indicated that the percentage of larger rice particles(d>2 mm)was significantly decreased from the initial(t=0)67%to 17%after 120 min digestion,along with the average median size(d50)decreasing from 3.7 mm to 2.1 mm.This indicated a powerful disintegration capacity of the DIVHS on food particles.The performance of the DIVHS was further validated by showing good qualitative matches of the gastric pH,particle size distribution and emptying profiles of cooked rice and noodles with the literature in vivo data3)The effects of two digestives on the digestion of starch and casein were studied by static in vitro digestion.The results show that the simplified method saves time and energy,is convenient for storage and preparation,and can achieve the experimental purpose of general static in vitro digestionThe above-mentioned results demonstrate that it is possible to achieve whatever gastric digestion and emptying situations in vivo by optimizing the operating parameters of the DIVHS.It is a reasonable approach to perform the gastric mixing,disintegration,digestion and emptying studies using the DIVHS,which is practically meaningful. |
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