In vitro and In vivo digestion comparison of bee pollen with or without wall-disruption

BACKGROUND

Bee pollen is considered as a treasure trove of human and animal nutrients as a result of its extensive nutritional and therapeutic properties. However, the sophisticated pollen wall can largely limit the digestibility and bioavailability of these nutrients.

RESULTS

An ultrasonication and high shear technique was used to break the walls of five species of bee pollen, including rape bee pollen, lotus bee pollen, camellia bee pollen, wuweizi bee pollen and apricot bee pollen. We compared the digestibilities of bee pollen with or without wall-disruption. After in vitro and in vivo digestion, unbroken bee pollen grains were still intact and the fragments of wall-disrupted bee pollen still remained as fragments. Mouse in vivo digestion results suggested that the wall-disrupted bee pollen was more easily emptied from the gastrointestinal tract than unbroken bee pollen. After dynamic in vitro digestion, the digestibilities of protein and crude fat in wall-disrupted bee pollen significantly increased to more than 80%; similarly, the release rates of amino acids and reducing sugars in all wall-disrupted samples were almost 1.5 and 2 times as much as those of unbroken samples.

CONCLUSION

Based on the results obtained in the present study, we strongly recommend that bee pollen should be wall-disrupted. © 2020 Society of Chemical Industry.

A review on the food digestion in the digestive tract and the used in vitro models

It is crucial to replicate or mimic the human digestive system conditions closely in model systems to have the food digestion-related data as accurate as possible. Thus, the data obtained could contribute to studies like those on the relationship between health and nutrition. This review aims to express the human digestion system's role in food digestion and compare the capability of the models used in simulations, especially the dynamic in vitro models. Activities of the human digestive system governing food digestion and the food matrix's disintegration mechanism in the digestive system were discussed. Dynamic in vitro models and their relevance to the human digestive system were described. Advancements in the last 20 years, as well as limitations of those artificial systems, with prospects, were discussed. Extensive use and improvement on these models will extend our knowledge of the food matrix and digestive system's complex interaction. Thus, it will be possible to design next-generation foods with improved health benefits.

Mixing and emptying of gastric contents in human-stomach: A numerical study

Stomach is one of the most important organs in human gastro-track. To better understand the operation of human-stomach, the process of mixing and emptying of gastric contents is simulated using a numerical method. The numerical results confirm that a fast pathway is located close to the lesser curvature of the stomach when water is emptied. However, this fast pathway doesn't exist when the gastric contents are composed of water and food boluses with different properties. The muscle contractions enhance the mixing of light food boluses and water, while they have limited effects on heavy food boluses. As a result, the foods are distributed in layers; heavy food boluses are located in the bottom layer. Besides the gastric motility and high viscosity of foods, the food matrix made of heavy food particles is also important to the formation of the Magenstrasse (stomach road). The food matrix and the zone of wrinkles behave like a porous medium which has higher flow resistance to the light food particles than to the water, leading to faster emptying of water. The water is emptied along the stomach wall since the flow resistance in the stomach wrinkles is smaller than the one in the food matrix. This mechanism is supported by the numerical results, while it might interpret the phenomena observed in the experiments.

Effects of digested Cheonggukjang on human microbiota assessed by in vitro fecal fermentation

In vitro fecal fermentation is an assay that uses fecal microbes to ferment foods, the results of which can be used to evaluate the potential of prebiotic candidates. To date, there have been various protocols used for in vitro fecal fermentation-based assessments of food substances. In this study, we investigated how personal gut microbiota differences and external factors affect the results of in vitro fecal fermentation assays. We used Cheonggukjang (CGJ), a Korean traditional fermented soybean soup that is acknowledged as healthy functional diet. CGJ was digested in vitro using acids and enzymes, and then fermented with human feces anaerobically. After fecal fermentation, the microbiota was analyzed using MiSeq, and the amount of short chain fatty acids (SCFAs) were measured using GC-MS. Our results suggest that CGJ was effectively metabolized by fecal bacteria to produce SCFAs, and this process resulted in an increase in the abundance of Coprococcus, Ruminococcus, and Bifidobacterium and a reduction in the growth of Sutterella, an opportunistic pathogen. The metabolic activities predicted from the microbiota shifts indicated enhanced metabolism linked to methionine biosynthesis and depleted chondroitin sulfate degradation. Moreover, the amount of SCFAs and microbiota shifts varied depending on personal microbiota differences. Our findings also suggest that in vitro fecal fermentation of CGJ for longer durations may partially affect certain fecal microbes. Overall, the study discusses the usability of in vitro gastrointestinal digestion and fecal fermentation (GIDFF) to imitate the effects of diet-induced microbiome modulation and its impact on the host.

Impact of processing techniques on the glycemic index of rice

Rice is an important starchy staple food and generally, rice varieties are known to have a higher glycemic index (GI). Over the years, the significance of GI on human health is being better understood and is known to be associated with several lifestyle disorders. Apart from the intrinsic characteristics of rice, different food processing techniques are known to have implications on the GI of rice. This work details the effect of domestic and industrial-level processing techniques on the GI of rice by providing an understanding of the resulting physicochemical changes. An attempt has been made to relate the process-dependent digestion behavior, which in turn reflects on the GI. The role of food constituents is elaborated and the various in vitro and in vivo approaches that have been used to determine the GI of foods are summarized. Considering the broader perspective, the effect of cooking methods and additives is explained. Given the significance of the cereal grain, this work concludes with the challenges and key thrust areas for future research.

Gastric emptying pattern and disintegration kinetics of cooked rice in a 3D printed in vitro dynamic digestion model ARK®

Understanding the gastric digestion process is essential for evaluating the bioaccessibility of nutrients from food matrices. The objective of this study was to investigate the kinetics of disintegration and gastric emptying patterns in a 3D printed stomach (ARK®) with white rice as the study sample. Modified power exponential model was used to fit the gastric retention data and the average t 1/2 and t lag values of the solid fractions were found to be 109.22 ± 4.20 and 84.16 ± 5.72 min, respectively. During the disintegration process, the weight percentage of medium size particles (∼0.35 mm) was found to be higher at 30 and 60 min. Moreover, there was a sharp decrease in the percentage of fine particles (<0.125 mm) at 90 and 120 min. The ARK® could effectively mimic the physiochemical process of the human stomach, providing promising insights for future studies on the development of novel and functional food products.

New insights into in vivo gastroduodenal digestion of oil-in-water emulsions: gastric stability and in vitro digestion modeling

In this paper, effect of emulsion stability on gastroduodenal emptying/secretion was reviewed and differentiated. Moreover, novel perspectives on physiology of gastric lumen, duodenum, and gall bladder were achieved using mathematical models, being useful for designing artificial digestive systems. In this regard, numerical data for dynamic gastric emptying/secretion were offered for gastric-stable and gastric-unstable emulsion intakes. It was shown that alterations in human gastric and duodenal volume follow, respectively, linear and sinusoidal curves, with high correlation coefficients (r² > 0.93). For both emulsions, about 30-40 mL ingesta discharged rapidly from stomach upon ingestion; However, further gastric emptying was regulated for the rest of digestion period, so that 0.1 mL/min oil was passing through duodenum. Intragastric evacuation of both emulsions started with a lag phase during which stomach stored secretions incrementally by slow gastric discharge. Lag phase ended with fat layering, when emptying considerably enhanced. This reduction was gradual for stable emulsion while unstable emulsion experienced a rapid emptying before slow declining trend. Along with initial gastric emptying, 87% of gallbladder content discharged into duodenum, prolonged up to the gradual reduction phase of stomach. Supplementary investigations are needed to quantify gastroduodenal secretions, particularly pepsin and pancreas in response to emulsion ingesta.

Food buffering capacity: quantification methods and its importance in digestion and health

Understanding the influence of food properties on buffering capacity will have an impact on gastric secretions and breakdown during digestion.

Response to comments on "A comparison of different physical stomach models and an analysis of shear stresses and strains in these system" by Wu and Chen (2020)

Physical stomach (in-vitro) models have considerable potential for answering questions about the dissolution and delivery of tablets, as well as answering fundamental questions about the hydrodynamics of the stomach and ultimately investigating diseases of the human gastrointestinal system. Physical gastrointestinal models have been compared in terms of their advantages and disadvantages. The structures of the produced stomach parts have been compared among the in-vitro models. The possible materials to manufacture the stomach models have also been summarized. This letter to the editor responds to the correspondence by Wu and Chen (2020) about our paper, aiming to further check and describe the substance in our paper.

Comments on "A comparison of different physical stomach models and an analysis of shear stresses and strains in these system" by Zhong and Langrish (2020)

Understanding of the fate of foods or specific nutrient(s) during digestion within the different compartments of the gastrointestinal (GI) tract is important for making healthier food products and formulate appropriate dietary advice. In vitro GI models have been extensively employed for digestion-related studies in recent years because they can overcome many of the difficulties associated with human or animal studies as the latter are not always technically, financially and ethically feasible. The origins, mechanisms, advantages/disadvantages and applications of typical in vitro physical stomach models have been summarized and compared in many review papers. These will contribute to the design and construction of more advanced and physiologically-relevant in vitro GI models. The letter to the editor comments on a recently published review paper aiming to clarify some inaccurate descriptions of the rat and human stomach systems in terms of the mechanisms of gastric peristalsis and the materials of construction for the stomach models.

In vitro gastric emptying characteristics of konjac glucomannan with different viscosity and its effects on appetite regulation

Konjac glucomannan (KGM) is associated with the satiety-enhancing property by imparting the food matrix with high viscosity. In the present study, rheology tests on KGM sol with different viscosities were conducted to understand its flow behavior as they presented in the mouth and stomach, and the in vitro gastric emptying characteristics of KGM were examined with a human gastric simulator. Then, their effects on subjective appetite, glycemia, and appetite-related hormones (insulin, GLP-1, PYY3-36, CCK-8, ghrelin) response were investigated by conducting a randomized, single-blind, crossover trial in 22 healthy adults (11 female and 11 male, mean age (years): 23.2 ± 2.0, BMI (kg m-2): 20.6 ± 2.1). The blood samples and ratings for subjective appetite were collected at regular time intervals after the subjects were fed with four test breakfasts (one control treatment and three experimental treatments) on four different days. An ad libitum lunch was provided to the subjects once they consumed the breakfasts and their food intake was recorded. As the viscosity increased, the gastric emptying rate was delayed despite a large part of the chyme viscosity lost during digestion. The satiating capacity of the test breakfast was significantly enhanced as its viscosity increased, the and subjects' sensation for hunger, fullness, desire-to-eat, and prospective food consumption differed significantly (p = 0.006, 0.000, 0.002, and 0.001, respectively) between the treatments. The secretion of glycemia and satiety-related hormones were beneficially modulated by the increased viscosity of the test meal but a small decrease in the ad libitum food intake was observed after the intervention of the viscous test breakfasts. Overall, elevating the meal viscosity moderately by using KGM could contribute to combating the challenge of hunger for people in the bodyweight management.

Further comments on "A comparison of different physical stomach models and an analysis of shear stresses and strains in these system" by Zhong and Langrish (2020)

Recently, Zhong and Langrish (2020a) presented an excellent review on typical in vitro physical stomach models reported in literature with an emphasis on their structures, materials, peristalsis, shear stress, pros and cons. We read it with great interest and provided further information (Wu & Chen, 2020) on our home-made rat and human stomach systems which were discussed in the review. Zhong and Langrish (2020b) followed up with a response letter to our note providing their observations on the matters. The current letter hopefully provides a sufficient response to their comments. It is believed through this back-and-forth process, the issues of uncertainty are nicely clarified for interested readers.

Simulating human digestion: developing our knowledge to create healthier and more sustainable foods

The gold standard for nutrition studies is clinical trials but they are expensive and variable, and do not always provide the mechanistic information required, hence the increased use ofin vitroand increasinglyin silicosimulations of digestion.

Practical and Durable Flexible Strain Sensors Based on Conductive Carbon Black and Silicone Blends for Large Scale Motion Monitoring Applications

Presented is a flexible capacitive strain sensor, based on the low cost materials silicone (PDMS) and carbon black (CB), that was fabricated by casting and curing of successive silicone layers—a central PDMS dielectric layer bounded by PDMS/CB blend electrodes and packaged by exterior PDMS films. It was effectively characterized for large flexion-angle motion wearable applications, with strain sensing properties assessed over large strains (50%) and variations in temperature and humidity. Additionally, suitability for monitoring large tissue deformation was established by integration with an in vitro digestive model. The capacitive gauge factor was approximately constant at 0.86 over these conditions for the linear strain range (3 to 47%). Durability was established from consistent relative capacitance changes over 10,000 strain cycles, with varying strain frequency and elongation up to 50%. Wearability and high flexion angle human motion detection were demonstrated by integration with an elbow band, with clear detection of motion ranges up 90°. The device’s simple structure and fabrication method, low-cost materials and robust performance, offer promise for expanding the availability of wearable sensor systems.