Increase In Sorbitol Concentration Research Articles

Effect of the high-pressure assisted-infusion processing on nutritional and antioxidant properties of mango cubes

The aim of this work was to evaluate the effect of the high-pressure assisted-infusion processing on the nutritional and functional properties of mango cubes immersed in a solution of sorbitol and calcium lactate. Three factors were studied: sorbitol concentration (20°Brix-40°Brix-60°Brix), calcium lactate concentration (0% w/w − 1% w/w − 2% w/w) and the pressure level (0.1 MPa–300 MPa-600 MPa). Sugar (sorbitol, glucose and sucrose), calcium and total phenols content and antioxidant capacity were determined. Results showed that the increase of sorbitol concentration from 20°Brix to 40°Brix caused higher sorbitol uptake and lixiviation of the natural compo in mango cubes. However, the increase of sorbitol concentration from 40°Brix to 60°Brix, had no significant effect on the diffusion of solutes. The high-pressure processing (HPP) favored the diffusion of solutes from solution to fruit, while the addition of the calcium counteracted this effect in most cases. Based on these results, the combined effect of 300 MPa and 60°Brix-2% calcium lactate was the most effective at preserving natural compounds of mango and conferred distinctive properties giving an added value to the final product due to its important nutritional implications. Therefore, high-pressure assisted-infusion processing could be considered as an effective method to preserve mango cubes with an acceptable nutritional value. Industrial relevanceThe present work showed that high-pressure assisted-infusion processing could be considered an alternative to develop mango-based products. Results showed that this process would allow preserving most of the natural compounds of the mango pieces, in addition to achieving distinctive characteristics, as a source of calcium. Therefore, the application of high-pressure assisted-infusion processing could open new opportunities for food industries to develop fresh and value-added products with characteristics similar to fresh fruit.

Placental TonEBP/NFAT5 Osmolyte Regulation in an Ovine Model of Intrauterine Growth Restriction1

TonEBP/NFAT5 (the tonicity-responsive enhancer binding protein/nuclear factor of activated T cells) modulates cellular response to osmotic changes by accumulating inositol and sorbitol inside the cells. Our objective was to assess placental osmolytes, TonEBP/NFAT5 RNA and protein expression, and signaling molecules across gestation between control and intrauterine growth restriction (IUGR) ovine pregnancies. Pregnant sheep were placed in hyperthermic conditions to induce IUGR. Placental tissues were collected at 55, 95, and 130 days gestational age (dGA) to measure inositol, sorbitol, TonEBP/NFAT5 (NFAT5), sodium-dependent myo-inositol transporter (SMIT; official symbol SLC5A3), aldose reductase (AR), and NADPH (official symbol DE-CR1). Placental weight was reduced in IUGR compared to controls at 95 and 130 dGA. Osmolyte concentrations were similar between control and IUGR placentas, but both groups demonstrated a significant decrease in inositol concentration and an increase in sorbitol concentration with advancing gestation. Cytosolic NFAT5 protein decreased significantly from 55 to 95 dGA in both groups, and nuclear NFAT5 protein increased only at 130 dGA in the IUGR group, but no differences were seen between groups for either cytosolic or nuclear NFAT5 protein concentrations. DE-CR1 concentrations were similar between groups and increased significantly with advancing gestational age. AR was lowest at 55dGA, and SLC5A3 increased with advancing gestational age. We conclude that both placental osmolytes inositol and sorbitol (and their corresponding proteins SLC5A3 and AR) change with gestational age and are regulated, at least in part, by NFAT5 and DE-CR1 (NADPH). The inverse relationship between each osmolyte across gestation (e.g., inositol higher in early gestation and sorbitol higher in late gestation) may reflect nutritional needs that change across gestation.

Solubilization of Indomethacin by Polysorbate 80 in Mixed Water-Sorbitol Solvents

The effect of indomethacin on the micellar properties of the non-ionic surfactant, polysorbate 80, in water-sorbitol mixtures containing up to 25% w/v sorbitol has been investigated by light scattering, photon correlation spectroscopy and viscometric techniques. The molecular weight of polysorbate 80 micelles containing solubilized indomethacin increased linearly with increase of sorbitol concentration. Solubilization of indomethacin resulted in an increase of micellar weight due not only to the incorporation of solubilizate but also to an increase in the number of polysorbate molecules per micelle. The micelles in all systems were most satisfactorily represented as oblate ellipsoids, the asymmetry and hydration of which increased with increase of sorbitol concentration. Indomethacin solubilization caused a restructuring of the micelle to produce a more symmetrical micelle of increased hydration.

Acid stability of anti-Helicobacter pyroli IgY in aqueous polyol solution.

IgY was separated from a hen's egg yolk that was immunized with Helicobacter pyroli. The anti-H. pyroli IgY activity at acidic pH and the suppressive effect of polyol on acid-induced inactivation of IgY were investigated. Sorbitol and xylitol were used as polyols. IgY was quite stable at pH 5-7. Irreversible inactivation of IgY was observed at pH below 4, and proceeded rapidly at pH below 3. The acid stability of IgY was enhanced in the presence of 30% sorbitol or above. In a 50% aqueous sorbitol solution, an acid-induced inactivation was almost completely suppressed at pH 3. However, the improvement of IgY activity was not observed in the aqueous xylitol solution. IgY showed almost the same activity as native IgY when sucrose was substituted for sorbitol. On the other hand, the xylitol replacement with sucrose did not enhance the acid stability of IgY. The acid-induced inactivation of IgY was related to tryptophyl fluorescence. Fluorescence emission spectra suggested that structural changes near the tryptophan residues may occur under acidic conditions. An increase in sorbitol concentration induced a blue shift. The fluorescence emission of IgY in a 50% sorbitol solution had a peak at 330 nm, which was the same emission peak that was exhibited by native IgY. Sorbitol could, therefore, be used as a good stabilizer of IgY under acidic conditions.

INHIBITORY EFFECT OF SORBITOL ON ACETAMINOPHEN ADSORPTION BY ACTIVATED CARBON

ABSTRACT The effective use of activated carbon as oral adsorbent in the primary treatment of acute acetaminophen poisoning was studied. The adsorption characteristics of acetaminophen onto activated carbons in presence of sorbitol were investigated in vitro. Both the equilibrium amount adsorbed and the removal rate of acetaminophen onto activated carbon were decreased with the increase of sorbitol concentration in solutions. The sorbitol concentration independency of the inhibition to the acetaminophen adsorption was recognized. It was concluded that the addition of sorbitol to the suspension of activated carbon inhibited the acetaminophen adsorption by activated carbon.

Mechanical, water vapor barrier and thermal properties of gelatin based edible films

Edible films are thin materials based on a biopolymer. The objectives of this work were to determine the water vapor permeability and the mechanical and thermal properties of edible films based on bovine hide and pigskin gelatins. These films were prepared with 1 g of gelatin/100 ml of water; 15–65 g sorbitol/100 g gelatin; and at natural pH. The samples were conditioned at 58% relative humidity and 22°C for 4 days before testing. The mechanical properties were determined by the puncture test and the water vapor permeability by gravimetric method at 22°C. For DSC analysis, samples were conditioned over silica gel for 3 weeks. Samples (∽10 mg) were heated at 5°C/min, between −150 and 150°C in a DSC TA 2010. A second scan was run after cell cooling with liquid nitrogen. As expected, the puncture force decreased and the puncture deformation and water vapor permeability increased with the sorbitol content. The origin of gelatin was important only above 25 g sorbitol/100 g gelatin. The DSC traces obtained in the first scan of samples with 15–35 g sorbitol/100 g gelatin, showed a well visible glass transition followed by a sol–gel transition. However, with the increase of sorbitol concentration, the glass transition became broader, typical of the system presenting a phase separation. The model of Couchman and Karazs for ternary system, was used to predict the Tg values as a function of sorbitol concentration.

Influence of diapause and temperature on cryoprotectant synthesis and cold hardiness in pupae of Pieris brassicae

1. 1. Cryoprotectant accumulation in pupae of Pieris brassicae was examined as a response to the diapause state and to low temperature exposure. 2. 2. Sorbitol is the major polyol cryoprotectant and occurs in significantly higher concentrations in diapausing than in non-diapausing pupae. Accumulation of sorbitol is apparently triggered as part of the photoperiodically induced diapause state but may be further enhanced by exposure to low temperature. 3. 3. Glycerol is present in all groups, but its consistently low level suggests that it does not function as a cryoprotectant. 4. 4. Diapause pupae have a mean T c only 2°C lower than non-diapause pupae, 24 hr after pupation and low temperature acclimation of diapause pupae does not significantly lower the T c despite the increase in sorbitol concentration. However, non-diapause pupae suffer pre-freeze mortality after exposure to −5°C for 14 days whereas diapause pupae survive — 15°C for up to 30 days. 5. 5. The significance of these results in the understanding of the interrelationships between diapause and cold tolerance in insects is discussed.

ΔpH-dependent activation of chloroplast coupling factors and external pH effects on the 9-aminoacridine response in lettuce and spinach thylakoids

Investigation of steady-state ΔpH and photophosphorylation in envelope-free chloroplasts extracted from lettuce or spinach leaves gave the following results. (1) The ratio of the rates of photophosphorylation at two nucleotide concentrations but at the same ΔpH adjusted by light intensity, and measured by 9-aminoacridine distribution, is independent of the magnitude of this ΔpH. Thus the flow-force relationships only represent the Δ μ H + activation of the coupling factors, each activated enzyme running at its maximum turnover rate. (2) Flow-force curves at pH 8.0 and pH 8.5 have similar shapes when ΔpH is delocalized with 200 μM hexylamine. Thus, activation of the coupling factors (CF) depends on the absolute value of ΔpH, regardless of the respective external and internal pH. This would mean that the basic process of activation is either voltage-dependent, or is due to the strictly coupled deprotonation of an external site of CF and protonation of an internal group. (3) The above result is not modified when GDP is used instead of ADP. This suggests that the shift in the equilibrium between active and inactive CF, due to tight binding of ADP, does not depend on the external pH. (4) With lettuce thylakoids, flow-force curves at pH 8.0 and 8.5 become identical only after a translation of the former by +0.15 along the ΔpH axis. Thus the response of 9-aminoacridine depends on the external pH, probably due to a change in the osmotic volume. The internal volume would be 40% higher at pH 8.5 than at pH 8.0. (5) Shifting the external pH from 8.0 to 8.5 has the same effect on 9-aminoacridine and imidazole responses. This confirms that the main effect is an increase of the lumenal volume at high pH. Direct estimations of this volume are qualitatively consistent with this view. (6) With spinach thylakoids, the effect of external pH on the 9-aminoacridine response is minimized. The 9-aminoacridine space change would be only 17% between pH 8.5 and pH 8.0. At pH 8.0, the light-induced uptake of 9-aminoacridine by lettuce thylakoids is insensitive to the increase in sorbitol concentration above 200 mM, whereas it decreases, as expected, with spinach thylakoids. (7) When the ΔpH is delocalized with 200 μM hexylamine, ΔpH and phosphorylation rates at low light intensities do not depend on the external pH. This means that not only the coupling factors, but also basal leaks, would be regulated by ΔpH and not by internal pH or a complex combination of external and internal pH. The results are discussed with reference to previous reports on the pH and ΔpH dependency of ATP synthesis by thylakoids. It seems likely that most early discrepancies were due to the different origins of the chloroplasts and to specific behaviour with respect to the ΔpH probe. This should be considered as a warning when one compares data obtained with membranes from different plant species.

Interactions between osmoregulation and the alternative respiratory pathway in Plantago coronopus as affected by salinity

Plantago coronopus L., a species from the coastal zone, was grown in culture solution with and without 50 mM NaCl. In addition it was transferred from a non‐saline solution to a solution containing 50 mM NaCl. Short term effects of NaCl on growth and various aspects of energy metabolism, including photosynthesis, shoot dark respiration, root respiration and the contribution of the SHAM‐sensitive alternative pathway to root respiration were investigated. The concentrations of soluble and insoluble non‐structural carbohydrates and of sorbitol a compatible osmotic solute in Plantago, in both shoots and roots were also determined.Growth of shoots and roots was largely unaffected by addition of 50 mM NaCl. Net photosynthesis, shoot dark respiration and the concentration of non‐structural carbohydrates in both shoots and roots were also unaffected by salinity. The rate of root respiration immediately decreased upon addition of 50 mM NaCl. This decrease was almost exclusively attributed to a decreased activity of the SHAM‐sensitive alternative pathway. The concentration of sorbitol in the roots increased quickly after addition of 50 mM NaCl, whilst the increase in sorbitol concentration in the shoots started later. The time course of the increase of sorbitol concentration was similar to that of the decrease in activity of the alternative pathway. During the first 12 h after exposure to 50 mM NaCl, the amount of carbohydrates which was saved in respiration, due to the decreased activity of the alternative pathway, was the same as that used for sorbitol synthesis in the roots. It is concluded that the activity of the alternative pathway decreased due to increased utilization of carbohydrates for sorbitol synthesis, according to a proposed ‘energy overflow model’.After 24 h, the sorbitol concentration in the cytoplasm of the root cells of plants transferred to a saline solution reached a level that was sufficient to compensate for 50 mM NaCl, assuming a cytoplasmic volume of ca. 10% of the total cell volume. The sorbitol concentration in roots of plants grown in a saline environment for several weeks was lower than that in roots of plants transferred to a saline environment for c. 24 h. It is suggested that sorbitol accumulated in roots of Plantago coronopus as an immediate reaction upon salinity, whilst other adaptations may occur thereafter.

RED CELL SORBITOL AN INDICATOR OF GLYCEMIC CONTROL

Blood glucose concentrations may change from physiologic to pathologic levels and vice versa within a few minutes. This is particularly true of insulin deficient diabetes and therefore the evaluation of glycemic control in children with diabetes is difficult. A less volatile indicator of hyperglycemia is the fraction of hemoglobin A (HbA) that is glycosylated (HbA1). HbA1 was determined chromatographically in 30 children with diabetes (13.9 ± 2.1%) and 10 non-diabetics (6.8 ± 1.4%). Incubation of washed red cells from diabetic patients in Krebs bicarbonate buffer with 5mM glucose for 3 hrs. results in no change in the % of HbA1. Sorbitol, a polyol of glucose, accumulates in red blood cells (RBC) in concentrations that correlate directly with the blood glucose concentration (r=.84). RBC sorbitol concentration in 30 ambulatory diabetics was 33nM/ccPRBC ± 13.7 while 10 non-diabetics had sorbitol levels of 5.3 ± 2.1. Incubation of non-diabetic RBC's in 50mM glucose produced an hourly linear increase in sorbitol concentration throughout the 3 hr. incubation reaching diabetic levels in one hour. Reduction of the glucose concentration to 5mM resulted in decreasing but still elevated sorbitol concentrations at one hour with a return to non-diabetic levels by 3 hours. Thus RBC sorbitol concentration may be a more useful indicator of glycemic control in diabetes than either the blood glucose or HbA1.