Pickering emulsion-templated ionotropic gelation of tocotrienol microcapsules: effects of alginate and chitosan concentrations and gelation process parameters

BACKGROUND

Throughout the past decade, Pickering emulsion has been increasingly utilized for the encapsulation of bioactive compounds due to its high stability and biocompatibility. In the present work, palm tocotrienols were initially encapsulated in a calcium carbonate Pickering emulsion, which was then subjected to alginate gelation and subsequent chitosan coating. The effects of wall material (alginate and chitosan) concentrations, gelation pH and time, and chitosan coating time on the encapsulation efficiency of palm tocotrienols were explored.

RESULTS

Our findings revealed that uncoated alginate microcapsules ruptured upon drying and exhibited low encapsulation efficiency (13.81 ± 2.76%). However, the addition of chitosan successfully provided a more complex and rigid external wall structure to enhance the stability of the microcapsules. By prolonging the crosslinking time from 5 to 30 min and increasing the chitosan concentration from 0.1% to 0.5%, the oil encapsulation efficiency was increased by 28%. Under the right gelation pH (pH 4), the extension of gelation time from 1 to 12 h resulted in an increase in alginate-Ca²⁺ crosslinkings, thus strengthening the microcapsules.

CONCLUSION

With the optimum formulation and process parameters, a high encapsulation efficiency (81.49 ± 1.75%) with an elevated oil loading efficiency (63.58 ± 2.96%) were achieved. The final product is biocompatible and can potentially be used for the delivery of palm tocotrienols. © 2021 Society of Chemical Industry.

Fabrication of oil-in-water emulsions as shelf-stable liquid non-dairy creamers: effects of homogenization pressure, oil type, and emulsifier concentration

BACKGROUND

The popularity of coffee, the second most consumed beverage in the world, contributes to the high demand for liquid non-dairy creamer (LNDC). In this study, palm olein emulsions (as LNDCs) were investigated as alternatives to the more common soybean oil-based LNDCs. LNDCs were prepared via different homogenization pressures (100-300 bar) using different types of oil (palm olein and soybean oil) and concentrations of DATEM emulsifier (5-20 g kg^-1 ).

RESULTS

Increases in homogenization pressure and emulsifier concentration were observed to have significant (P < 0.05) effects on the physicochemical properties (particle size, pH, and viscosity) of the LNDCs. Palm olein and soybean oil LNDCs prepared using 15 g kg^-1 and 10 g kg^-1 DATEM emulsifier, respectively, were determined to be the most stable (as observed throughout a 15-day storage period at ambient temperature of 28 ± 2 °C), with properties closest to those of a commercial LNDC. When added to black coffee, both LNDCs displayed a good whitening effect by increasing the L* value from 26.73 ± 0.16 (black coffee) to ≥40.82 ± 0.56 (black coffee + LNDCs). Sensory evaluation showed that there were no significant (P > 0.05) differences between the prepared and commercial LNDCs in terms of their color, appearance, and overall acceptability.

CONCLUSION

Shelf-stable LNDCs with qualities comparable to commercial LNDC were successfully fabricated. Valuable insights into the effects of homogenization pressure, oil type, and emulsifier concentration, as well as functionality and consumer acceptance of the LNDCs when added into black coffee, were obtained. © 2020 Society of Chemical Industry.

Stabilization and Release of Palm Tocotrienol Emulsion Fabricated Using pH-Sensitive Calcium Carbonate

Calcium carbonate (CaCO3) has been utilized as a pH-responsive component in various products. In this present work, palm tocotrienols-rich fraction (TRF) was successfully entrapped in a self-assembled oil-in-water (O/W) emulsion system by using CaCO3 as the stabilizer. The emulsion droplet size, viscosity and tocotrienols entrapment efficiency (EE) were strongly affected by varying the processing (homogenization speed and time) and formulation (CaCO3 and TRF concentrations) parameters. Our findings indicated that the combination of 5000 rpm homogenization speed, 15 min homogenization time, 0.75% CaCO3 concentration and 2% TRF concentration resulted in a high EE of tocotrienols (92.59-99.16%) and small droplet size (18.83 ± 1.36 µm). The resulting emulsion system readily released the entrapped tocotrienols across the pH range tested (pH 1-9); with relatively the highest release observed at pH 3. The current study presents a potential pH-sensitive emulsion system for the entrapment and delivery of palm tocotrienols.

Effects of Environmental Stresses and in Vitro Digestion on the Release of Tocotrienols Encapsulated Within Chitosan-Alginate Microcapsules

Considering the health benefits of tocotrienols, continuous works have been done on the encapsulation and delivery of these compounds. In this study, we encapsulated tocotrienols in chitosan-alginate microcapsules and evaluated their release profile. Generally, these tocotrienols microcapsules (TM) displayed high thermal stability. When subjected to pH adjustments (pH 1-9), we observed that the release of tocotrienols was the highest (33.78 ± 0.18%) under basic conditions. The TM were also unstable against the effect of ionic strength, with a high release (70.73 ± 0.04%) of tocotrienols even at a low sodium chloride concentration (50 mM). As for the individual isomers, δ-tocotrienol was the most sensitive to pH and ionic strength. In contrast, β-/γ-tocotrienols were the most ionic-stable isomers but more responsive toward thermal treatment. Simulated gastrointestinal model showed that the chitosan-alginate-based TM could be used to retain tocotrienols in the gastric and subsequently release them in the intestines for possible absorption.

Reduction of saltiness and acrylamide levels in palm sugar-like flavouring through buffer modification and the addition of calcium chloride

Palm sugar-like flavouring (PSLF) is a type of flavour product that is formed by heating amino acids and sugar under specific heating conditions. Unfortunately, PSLF has a salty taste and contains high amounts of acrylamide. Hence, the objective of this research was to reduce saltiness and acrylamide without negatively affecting the aroma properties of PSLF. A decrease in the sodium phosphate (NaHPO₄) buffer concentration from 0.20 to 0.02 M was found to reduce sodium to approximately 15% of the level found in original PSLF. A further decrease (~25%) in the sodium content was achieved by removing monobasic sodium phosphate (NaH₂PO₄) from the buffer system. Meanwhile, the addition of CaCl₂ at 20–40 mg/L reduced the acrylamide content in PSLF by as much as 58%. A CaCl₂ concentration of 20 mg/mL was most favourable as it most efficiently suppressed acrylamide formation while providing an acceptably high flavour yield in PSLF. In view of the high acrylamide content in PSLF, additional work is necessary to further reduce the amount of acrylamide by controlling the asparagine concentration in the precursor mixture.

Carboxymethyl-β-cyclodextrin conjugated magnetic nanoparticles as nano-adsorbents for removal of copper ions: synthesis and adsorption studies

A novel nano-adsorbent, carboxymethyl-β-cyclodextrin modified Fe(3)O(4) nanoparticles (CMCD-MNPs) is fabricated for removal of copper ions from aqueous solution by grafting CM-β-CD onto the magnetite surface via carbodiimide method. The characteristics results of FTIR, TEM, TGA and XPS show that CM-β-CD is grafted onto Fe(3)O(4) nanoparticles. The grafted CM-β-CD on the Fe(3)O(4) nanoparticles contributes to an enhancement of the adsorption capacity because of the strong abilities of the multiple hydroxyl and carboxyl groups in CM-β-CD to adsorb metal ions. The adsorption of Cu(2+) onto CMCD-MNPs is found to be dependent on pH and temperature. Adsorption equilibrium is achieved in 30 min and the adsorption kinetics of Cu(2+) is found to follow a pseudo-second-order kinetic model. Equilibrium data for Cu(2+) adsorption are fitted well by Langmuir isotherm model. The maximum adsorption capacity for Cu(2+) ions is estimated to be 47.2mg/g at 25 °C. Furthermore, thermodynamic parameters reveal the feasibility, spontaneity and exothermic nature of the adsorption process. FTIR and XPS reveal that Cu(2+) adsorption onto CMCD-MNPs mainly involves the oxygen atoms in CM-β-CD to form surface-complexes. In addition, the copper ions can be desorbed from CMCD-MNPs by citric acid solution with 96.2% desorption efficiency and the CMCD-MNPs exhibit good recyclability.

The WAND local anesthetic delivery system: a more pleasant experience for anal anesthesia

PURPOSE

The WAND is a computer-controlled local anesthetic delivery system. Its use has been proven to be more comfortable for dental patients. The purpose of this study is to explore its applicability to anal procedures. Our hypothesis is that the WAND will provide greater comfort during anesthesia delivery while achieving the same anesthetic effect as traditional syringe technique.

METHODS

Twenty patients with painless anal pathology were randomized to receive anal anesthesia using either the WAND or traditional syringe technique to a randomly selected half of the anoderm (right or left). The opposite side was then anesthetized by the alternate method, allowing patients to act as their own control. Objective and subjective pain scores were obtained from the patient after each mode of delivery. An independent observer interpreted the patient's tolerance by giving a subjective pain score. The volume of anesthetic used was recorded. Adequacy of anesthesia was tested by a pinch test.

RESULTS

Sixteen (80 percent) of the 20 patients preferred the use of the WAND. Objective and subjective pain scores per the patients and subjective pain scores per the observer were significantly lower for the WAND than for traditional syringe technique (P < 0.05). The mean volume of local anesthetic used with the WAND was 1.7 ml compared with 3.2 ml for traditional syringe technique (P < 0.005). Anesthesia achieved with the WAND was as good as that achieved with traditional syringe technique when the pinch test was used.

CONCLUSION

The WAND is as effective as the traditional syringe technique in the delivery of anal anesthesia while providing a more comfortable experience for the patient.

The effect of lung injury and excessive lung fluid, on impedance cardiac output measurements, in the critically ill

OBJECTIVES

To investigate the relationship between the attenuation of impedance cardiac output (IC(co)) measurements and lung fluid content in critically ill patients.

DESIGN

Observational study.

SETTING

Intensive Care Unit of a major teaching hospital in Hong Kong.

PATIENTS

Twenty-four critically ill patients who required a pulmonary artery catheter.

MEASUREMENTS AND MAIN RESULTS

Triplicate thermodilution cardiac output (TD(co)) and BoMed NCCOM3 (IC(co)) measurements were made simultaneously on a single occasion in each patient. Lung fluid accumulation was assessed by: (a) thoracic impedance (Zo), (b) radiological assessment of chest X-rays using an alveolar consolidation score (0-4) and (c) scoring the degree of hypoxia and use of positive end-expiratory pressure (PEEP). Offsets (TD(co)-IC(co))/TD(co), expressed as percentage, were compared with these indices of excess lung fluid. Patients were divided into those with sepsis (n = 13), fluid balance problems (n = 5) and cardiothoracic problems (n = 6). Mean cardiac output values were: 6.7 l/min TD(co) (range 3.6-12.9) and 5.2 l/min IC(co) (range 2.7-9.0). Overall the TD(co) and IC(co) values showed great variance, with a bias and limits of agreement of 1.49 +/- 4.16 l/min, or +/- 69%. In septic patients, increasing offset was correlated with decreases in Zo (r = 0.73, P = 0.005) and increases in alveolar consolidation score (r = 0.72, P = 0.005).

CONCLUSIONS

The BoMed under-estimates cardiac output in critically ill patients. In septic patients the degree of attenuation of IC(co) can be related to the extent of lung injury and fluid accumulation within the thorax.

Isoleucyl-tRNA synthetase of Methanobacterium thermoautotrophicum Marburg. Cloning of the gene, nucleotide sequence, and localization of a base change conferring resistance to pseudomonic acid

The ileS gene encoding the isoleucyl-tRNA synthetase of the thermophilic archaebacterium Methanobacterium thermoautotrophicum Marburg was isolated and sequenced. ileS was closely flanked by an unknown open reading frame and by purL and thus is arranged differently from the organizations observed in several eubacteria or in Saccharomyces cerevisiae. The deduced amino acid sequence of isoleucyl-tRNA synthetase was compared with primary sequences of isoleucyl-, valyl-, leucyl-, and methionyl-tRNA synthetases from eubacteria and yeast. The archaebacterial enzyme fitted well into this group of enzymes. It contained the two short consensus sequences observed in class I aminoacyl-tRNA synthetases as well as regions of homology with enzymes of the isoleucine family. Comparison between the isoleucyl-tRNA synthetases of M. thermoautotrophicum yielded 36% amino acid identity with the yeast enzyme and 32% identity with the corresponding enzyme from Escherichia coli. The ileS gene of the pseudomonic acid-resistant M. thermoautotrophicum mutant MBT10 was also sequenced. The mutant enzyme had undergone a glycine to aspartic acid transition at position 590, in a conserved region comprising the KMSKS consensus sequence. The inhibition constants of pseudomonic acid, KiIle and KiATP, for the mutant enzyme were 10-fold higher than those determined for the wild-type enzyme. Both the mutant and the wild-type ileS gene were expressed in E. coli, and their products displayed the expected difference in sensitivity toward pseudomonic acid.

Vitamin A reserve of liver in health and coronary heart disease among ethnic groups in Singapore

1. The vitamin A content of human liver tissue was determined in 363 autopsy samples. The sample comprised a total of 181 subjects dying after accidents and 182 dying from coronary heart disease among Singapore ethnic groups of both sexes. 2. The medium vitamin A reserve was 146 mg/kg in accident victims and 141 mg/kg in those who had died of coronary heart disease. Of all the samples 16% contained less than 40 mg/kg, 45% had 100-300 mg/kg, while 9% contained more than 500 mg/kg liver. 3. Among the accident victims, Indians had the lowest median liver vitamin A reserve (118 mg/kg) compared with that in other ethnic groups (137 mg/kg in Chinese, 191 mg/kg in Malays, 155 mg/kg in Caucasians). 4. The ethnic distribution of vitamin A reserve in coronary deaths was similar to that in accident victims. 5. There was no significant difference between the sexes in hepatic vitamin A reserve. 6. The distribution of vitamin A reserve in all the groups was skewed to the right.

Preparation of bovine blood coagulation factors X1 and X2

A method is described for the preparation of both Factor X1 and Factor X2 from citrated bovine blood. The proteins from the plasma were first adsorbed on barium citrate by adding barium chloride solution. The precipitate formed was stirred with citrate/NaOH pH 6.9 buffer; barium and other clotting factors were removed by adding ammonium sulphate (up to 30% saturation) to the suspension. The Factor X was then precipitated by 65% ammonium sulphate, after resolution in citrate buffer chromatographed on DEAE-Sephadex and purified by rechromatography on DEAE-Sephadex and DEAE-Sepharose, respectively. This yielded Factor X1 and Factor X2 with respective purifications of about 16 000 and 24 000-fold that of the plasma. The apparent molecular mass of both Factor X1 and Factor X2 was 55 kDa as estimated by the sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Factor X2 had a higher specific biological activity of about 340 000 units/mg compared to that of Factor X1 of about 230 000 units/mg.

Energy balance study in Singapore medical students

Energy cost of rest and various common daily activities was measured in 7 male and 16 female medical students by using a Max-Planck respirometer and a Lloyd's gas analysis apparatus. The average weight of male and female subjects during the course of the study was 67.3 +/- 14.2 and 51.2 +/- 5.1 kg, respectively. The average energy expenditure per day was estimated from a diary of activities for a period of 7 days. The average daily intake of energy was computed from food tables and based on weighed amounts of raw materials of food consumed over the same 7-day period when energy expenditure was determined. The average energy expenditure of rest and different activities was found to be significantly lower than the figures published for western subjects. The daily energy intake and expenditure were 2,138 +/- 217 kcal (9.0 +/- 0.9 MJ) and 1,894 +/- 168 kcal (8.0 +/- 0.7 MJ), respectively, in male medical students, giving a positive balance of 244 kcal (1.0 MJ). The values of the same in female medical students were 1,711 +/- 292 kcal (7.2 +/- 1.2 MJ) and 1,474 +/- 211 kcal (6.2 +/- 0.9 MJ) with a balance of 237 kcal (1.0 MJ).