Effect of mechanical properties on in vitro dynamic digestion of starch contained in hydrogels

BACKGROUND

This study evaluates the effect of mechanical properties on the in vitro dynamic gastrointestinal digestion of hydrogels containing starch (HCSs) as a model for studying the nutrient digestibility of solid foods. It provides a useful theoretical basis for the processing of specific foods.

RESULT

Four types of HCSs with two levels of fracture stress (17.4-20.9 kPa and 55.5-57.6 kPa) and two levels of fracture strain (25.4-28.5% and 53.7-57.4%) were prepared. For these HCSs, the degree of gastric disintegration of hydrogels reduced significantly when fracture strain exceeded 30% (P < 0.05). The gastric emptying of HCS particles was also affected by mechanical properties. For example, even at the same level of fracture stress (ca. 20 kPa), the dry solids retention ratio decreased markedly from 0.90 to 0.43 with a decrease in fracture strain from 53.7% to 25.4% (P < 0.05). For the starch hydrolysis of HCSs after gastric digestion, more than 70% of starch in the particles of all types of HCSs emptied did not undergo digestion. The starch hydrolysis of HCSs during small intestinal digestion was also influenced by their mechanical properties. Fracture strains of HCSs, rather than their fracture stress, affected starch digestibility in hydrogels.

CONCLUSION

The gastric disintegration, the gastric emptying, and the starch hydrolysis of HCSs are suppressed when fracture strain exceeded 30%. Even with the amount of nutritional components contained in hydrogels being the same, the in vitro gastrointestinal digestion behavior of HCSs depends on their mechanical properties. This behavior has the potential to be used in the design of processed foods with controlled bioaccessibility. © 2023 Society of Chemical Industry.

Printability of Nixtamalized Corn Dough during Screw-Based Three-Dimensional Food Printing

This study aimed to analyze the printability of corn-based dough during screw-based three-dimensional (3D) food printing (3DFP) by relating its rheological and mechanical properties to its screw-based 3DFP performance, with the objective of providing insights into the utilization of corn-based dough to produce 3D-printed foods. Screw-based 3DFP was performed using seven corn-based doughs with different nixtamalized corn flour (NCF) and water contents. Afterward, their rheological and mechanical properties were analyzed and associated with their screw-based 3DFP performance. The results showed that stable printability was obtained within a specific range of NCF content in the dough (30-32.5 wt%). Below this range, the 3D-printed foods flattened, while above it, the extrudability of the dough was affected. The printability of the dough was influenced by different rheological and mechanical properties, depending on the stage of the screw-based 3DFP process. During the extrusion stage, the loss tangent at nozzle strain, yield stress, apparent viscosity, and adhesiveness mainly affected the extrudability of the dough. In contrast, the loss tangent at minimum strain, elastic modulus, Young's modulus, and hardness influenced the self-supporting stage. Therefore, it is important to find a balance between all of these properties, where stable extrudability and self-supporting of the 3D structure are achieved.

PIV and CFD studies on analyzing intragastric flow phenomena induced by peristalsis using a human gastric flow simulator

The intragastric flow phenomena was analyzed using a human gastric flow simulator. The flow-field induced by gastric peristalsis was quantitatively measured in both liquid and liquid-solid gastric contents.

Application of nitrifying and denitrifying processes to waste management of aquatic life support in space

Since a biological filter with nitrifying bacteria was firstly applied to aquatic animal experiments in IML-2 mission, the reactor system has been further studied to combine both nitrifying and denitrifying reactions under aerobic environment allowing an efficient removal of inorganic nitrogen from animal wastes. The isolated denitrifying bacteria had an activity under aerobic condition with rice straw providing a metabolic carbon source for the reaction. The advantage of the aerobic biological filter having both nitrifying and denitrifying activities may allow to reduce the size of the life support system and also for its manageability. The paper reports characteristics of the biological filter systems used for the IML-2 mission and the improved combined filter system having both nitrifying and denitrifying activities, and discuss its application to space experiments.

A crowbarless power supply for klystrons

A new crowbarless power supply is to be installed at the New SUBARU storage ring. A high-power switching inverter unit eliminates the need for expensive and unstable crowbar circuits for the klystron power supply. It also realizes a very small voltage ripple in the low-frequency region. This is an important characteristic, especially in a quasi-isochronous storage ring such as New SUBARU.

Maternal urinary beta-core fragment of hCG/creatinine ratios and fetal chromosomal abnormalities in the second trimester of pregnancy

Our aim was to evaluate the potential value of the ratio of the maternal urinary beta-core fragment of human chorionic gonadotropin (beta C-hCG) to creatinine (Cr) in discriminating between normal pregnancies and pregnancies associated with fetal chromosomal abnormalities. We hypothesized that pregnancies with fetal chromosomal abnormalities had abnormal quantities of beta C-hCG in the urine. The aims of the present study were to investigate retrospectively whether maternal urinary ratios of beta C-hCG/Cr are abnormal in women carrying fetuses with chromosome aberrations and to determine normative median values and a reference range for beta C-hCG/Cr between 14 and 19 weeks' gestation. Maternal urinary beta C-hCG and Cr concentrations were measured in 150 healthy women from 14 to 19 weeks and compared with ten cases of fetal chromosomal abnormalities matched for gestational age. The preliminary cut-off points corresponded to 0.29 multiple of the normal median (MOM) and 2.83 MOM, which were equivalent to the tenth and 90th centiles of the normal range. Of ten cases of fetal chromosomal abnormalities, one out of one (100 per cent) case with trisomy 18 and three of four (75 per cent) cases of variant 9 chromosomes had low beta C-hCG/Cr (< or = 0.29 MOM). One of five (20 per cent) cases with Down syndrome had elevated beta C-hCG/Cr (> or = 2.83 MOM). Urinary beta C-hCG/Cr ratios obtained in the second trimester may be useful for improved detection efficiency of Down syndrome, trisomy 18, and inversion of chromosome 9. Second-trimester maternal urinary beta C-hCG/Cr should be investigated further as a potential marker for fetal chromosome anomalies.

A retrospective study of glucose metabolism in mothers of large babies

OBJECTIVE

To evaluate retrospectively the glucose metabolism of women who gave birth to large babies.

RESEARCH DESIGN AND METHODS

Within the first 3 days of postpartum, HbA1c of the dense erythrocytes and glycated albumin were measured. The sample group was comprised of 59 women who gave birth to heavy-for-dates infants. Fifty-five women who had average-sized infants formed the control group. Both groups had normal results on screening for gestational diabetes mellitus (GDM) by 28 weeks of gestation. The dense erythrocyte fractionation was obtained by capillary centrifugation for measurement of stable HbA1c.

RESULTS

Mothers of heavy-for-dates infants had a significantly higher level of HbA1c of the dense erythrocytes (mean +/- SD; 5.86 +/- 0.68 vs. 5.50 +/- 0.70%, P = 0.015) and a higher maternal body mass index (BMI) (mean +/- SD; 26.5 +/- 2.9 vs. 24.1 +/- 2.3 kg/m2, P < 0.00001) than control mothers. Differences in the occurrence of high levels of HbA1c of the dense erythrocytes and maternal BMI were statistically significant (P < 0.01, P < 0.05) between the two groups, but no difference was noted in glycated albumin. There was no statistical correlation between high levels of HbA1c of the dense erythrocytes and maternal obesity.

CONCLUSIONS

High HbA1c levels of the dense erythrocytes and maternal obesity are independent factors that affect fetal oversize. Heavy-for-dates infants may be a consequence of maternal hyperglycemia in late pregnancy. This maternal hyperglycemia was not detected by the routine screening test for GDM.

Glycated hemoglobin of fractionated erythrocytes, glycated albumin, and plasma fructosamine during pregnancy

OBJECTIVE

To evaluate glucose metabolism during pregnancy, we measured plasma fructosamine, glycated albumin, and the stable glycated hemoglobin of the light and dense erythrocytes.

STUDY DESIGN

The abnormal glucose tolerance group comprised patients with gestational diabetes and those with one abnormal value on a 75 gm oral glucose tolerance test. Erythrocyte fractionation was performed by capillary centrifugation.

RESULTS

In normal pregnancy glycated hemoglobin of the light erythrocytes was reduced in the second and third trimesters (3.42% +/- 0.62% [mean +/- SD] [n = 306] in the first trimester, 2.15% +/- 0.48% [n = 353] in the second, and 2.06% +/- 0.58% [n = 300] in the third), and dense erythrocytes were higher in the third trimester (first 4.59% +/- 0.46%, second 4.70% +/- 0.49%, third 5.29% +/- 0.73%). Glycated albumin and fructosamine followed a pattern similar to the light erythrocytes. The group with abnormal glucose tolerance had significantly higher levels of glycated hemoglobin of the light erythrocytes in the first and third trimesters and glycated hemoglobin of the dense erythrocytes and glycated albumin in all trimesters.

CONCLUSION

The biphasic change in nonfractionated glycated hemoglobin is the sum of the lower glycated hemoglobin of the light erythrocytes and the higher glycated hemoglobin of the dense erythrocytes in late pregnancy. The stable glycated hemoglobin of fractionated erythrocytes and the glycated albumin accurately reflect maternal glucose metabolism during pregnancy.

Endoneurial blood supply to peripheral nerves is not uniform

Peripheral nerves are not uniformly susceptible to the effects of ischemia in human and experimental ischemic neuropathies. Since endoneurial blood flow is directly proportional to the number of endoneurial capillaries, we studied endoneurial capillary density at multiple levels of the peripheral nerves of normal rats. Capillary density was lowest in the sciatic and proximal tibial nerves and significantly higher in dorsal and ventral roots and distal tibial and plantar nerves. Endoneurial capillary density corresponds to the hierarchy of susceptibility to ischemic nerve damage in human and experimental ischemic neuropathies. These findings suggest that susceptibility of peripheral nerves to ischemia is determined, at least in part, by the density of endoneurial capillaries.

The effect of aminoguanidine on the blood-retinal barrier in streptozocin-induced diabetic rats

The effect of aminoguanidine hydrochloride (AG) on the blood-retinal barrier was studied in rats with streptozocin-induced diabetes. Half of the rats were given AG (100 mg/kg/day) while the remainder received no treatment. Vitreous fluorophotometry was performed on all rats before STZ injection and 2 weeks after induction of diabetes mellitus. Two weeks after STZ injection the mean 60-minute vitreous fluorescein concentration following dye injection had increased more in the nontreated group than in the AG-treated group, suggesting that AG may have some beneficial effect on the breakdown of the blood-retinal barrier.

Piroxicam may reduce the rate of progression of experimental diabetic neuropathy

We studied the effect of piroxicam, a long acting inhibitor of platelet aggregation, on the evolution of neuropathy in diabetic rats. We treated half of the rats with piroxicam and serially studied sensory and motor nerve conduction during 20 weeks of diabetes. The sensory nerve action potential amplitude was the same in treated and untreated rats before diabetes, and declined steadily as duration of diabetes increased. In treated rats, the amplitude fell more slowly and by 16 weeks and thereafter was significantly higher than in untreated rats. Sensory conduction velocity and motor nerve conduction studies were not affected by piroxicam treatment. The results suggest that piroxicam may slow the rate of progression of neuropathy in diabetic rats, probably by inhibiting platelet aggregation.