Calcium Lactate Pentahydrate Research Articles

Construction biotechnology: improving mortar properties through calcium carbonate precipitation using a novel strain of the bacterium Neisseria perflava

In construction technology, there are significant efforts to reduce environmental emissions, particularly NH3 and other pollutants. This study marks the first application of CaCO3 biomineralization biotechnology in microbially induced calcium carbonate precipitation (MICCP) to enhance mortar properties using the non-pathogenic Neisseria perflava strain SKC/VA-3, which employs carbonic anhydrase mechanisms. The results demonstrated that N. perflava could significantly improve the physical and mechanical characteristics of mortar. Incorporating N. perflava and calcium lactate pentahydrate resulted in a 20% increase in compressive strength and a 14% rise in indirect tensile strength of the mortar. Examination through scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM–EDS) revealed calcite formation within the microstructure of the bio-mortar. Additionally, self-healing assessments indicated that calcite precipitation, driven by bacterial metabolism, also occurred on the cracked surfaces of the bacterial mortar, suggesting potential for reduced maintenance and increased material longevity. This study provides the first report on the use of N. perflava for bio-mortar enhancement and represents a novel biotechnological approach to improving the properties of mortar and other cementitious materials. The utilization of N. perflava in bio-mortar represents a groundbreaking biotechnological advance, potentially enhancing mortar and other cement-based materials. This development contributes to sustainable, durable, and environmentally friendly construction technologies.

Biomineralization Biotechnology Utilizing Lysinibacillus sphaericus to Improve Mechanical Properties of Mortar

Biomineralization has notably enhanced the qualities of cement-based materials, particularly through bacterial-facilitated calcite precipitation via calcium lactate oxidation. However, existing research mainly targets self-healing aspects, with little focus on bio-based mortar properties. Consequently, this study provides a comprehensive examination of the enhancements in dry density, ultrasonic pulse velocity (UPV), and flexural strength, achieved through the application of a novel indigenous bacterial strain (Lysinibacillus sphaericus strain SKC/VA-1) from Indonesia, coupled with the incorporation of calcium lactate pentahydrate as an additive. A total of six mortar samples were prepared to investigate the influence of bacteria on the properties of mortar through biomineralization. The samples included plain mortar (M), mortar mixed with calcium lactate pentahydrate (ML), mortar mixed with a 10% v/v bacterial inoculum (MB1), mortar mixed with calcium lactate pentahydrate and a 10% v/v bacterial inoculum (MLB1), mortar mixed with a 20% v/v bacterial inoculum (MB2), and mortar mixed with calcium lactate pentahydrate and a 20% v/v bacterial inoculum (MLB2). The employment of a distinct bacterial strain for oxidizing calcium lactate represents an innovative aspect of the current study. The presence of organic calcium was found to have no adverse effects on the mortar matrix. Optimal inoculum concentrations of bacteria (10% v/v), in conjunction with calcium lactate pentahydrate, yielded superior mechanical properties. Mineralogical characterization via X-ray diffraction and microstructural analysis through scanning electron microscopy substantiated the incidence of calcite precipitation, which facilitated pore infilling and consequently augmented both the ultrasonic pulse velocity and the flexural strength of the mortar.

Efficient, Green, and Low-Cost Conversion of Bivalve-Shell Wastes to Value-Added Calcium Lactate.

This work presents the efficient, green, and low-cost preparation of calcium lactate by using bivalve-shell wastes (cockle, mussel, and oyster shells) as raw materials. Three bivalve shells, a cockle, mussel, and oyster, were used separately as an alternative calcium-source material for the preparation of calcium lactate. The bivalve-shell waste was cleaned and milled, obtaining calcium carbonate (CaCO3) powder, which reacted to the lactic acid, forming calcium lactate. The effects of different calcium sources (cockle, mussel, and oyster) and different lactic acid concentrations (6, 8, and 10 mol/L) on the physicochemical properties of the synthesized calcium lactates were then investigated. The results pointed out that the highest solubility of the product was observed when 6 mol/L lactic acid and cockle-shell derived CaCO3 were employed for the calcium lactate preparation. The thermal decompositions of all calcium lactates occurred in three processes: dehydration, ethyl-lactate elimination, and decarbonization, respectively. The results, obtained from an infrared spectrometer, X-ray diffractometer, thermogravimetric analyzer, and scanning electron microscope, confirmed the formation of calcium lactate pentahydrate (Ca(CH3CHOHCOO)2·5H2O). The diffractograms also indicated the presence of two enantiomers of Ca(CH3CHOHCOO)2·5H2O, namely, of dl- and l-enantiomers, which depended on the lactic acid concentration used in the preparation process. The morphologies of calcium lactates show the firewood-like crystals in different microsizes, together with smaller irregular crystals. In summary, this work reports an effective process to prepare the valuable calcium lactates by using the cheap bivalve-shell-derived CaCO3 as a renewable calcium source.

Morphology Control of Hydroxyapatite as a Potential Reinforcement for Orthopedic Biomaterials: The Hydrothermal Process

Hydroxyapatite (HAp) of different morphologies was prepared by the direct decomposition of calcium lactate pentahydrate chelates using dipotassium hydrogen phosphate under hydrothermal conditions. The proposed technique allows for precise control of the HAp crystals morphology and product purity, which are necessary for biomedical applications. The synthesis parameters such as reagent concentrations, pH, reaction time, temperature, pressure, and stirring rate were optimized in order to produce calcium phosphates (CaPs) ceramics with restricted morphologies and composition. As a result, we obtained hydroxyapatite in the form of whiskers, hexagonal rods, nano particles, flowers, and cylinders. The products were characterized according to their structure (FTIR and XRD), morphology (SEM), and functional properties, i.e., the specific surface area. The obtained results indicate that the reagent concentration and pH values have the greatest impact on the HAp properties; however, the proper combination of all the mentioned parameters should be considered when there is a need for a bioceramic with defined physicochemical properties and an appropriate morphology.

Effect of reaction time, heating and stirring rate on the morphology of HAp obtained by hydrothermal synthesis

Hydroxyapatite (HAp) whiskers were prepared in reaction of calcium lactate pentahydrate and orthophosphoric acid. Synthesis were carried out in different conditions with using hydrothermal reactor. The benefit of the hydrothermal technique is the simple and precise control of the HAp crystals morphology, which is achieved by employing varying initial concentrations of starting reagents as well as different conditions of synthesis. The effect of time of synthesis, stirring and heating rate of the reaction on HAp morphology and composition was investigated. During the synthesis the following experimental parameters were varied independently: time of synthesis (3, 5, 7 h), stirring rate (0, 62.5, 125, 250, 500, 750 rpm), the reaction heating rate (0.2, 0.5, 0.7, 1.0, 1.5, 2.5 °C min−1). All syntheses were carried out with the constant molar Ca/P ratio of 1.67 in starting solutions, which is equivalent to that of stoichiometric HAp. The Ca2+ ion concentrations in starting solutions for synthesis were 0.05 and 0.1 mol dm−3. Syntheses were carried out under 20 bar. The obtained products were characterized using different method like XRD, SEM, and FTIR. It was shown that the significant majority of samples prepared were identified as pure HAp.

Bioceramics Based on β-Calcium Pyrophosphate.

Ceramic samples based on β-calcium pyrophosphate β-Ca2P2O7 were prepared from powders of γ-calcium pyrophosphate γ-Ca2P2O7 with preset molar ratios Ca/P = 1, 0.975 and 0.95 using firing at 900, 1000, and 1100 °C. Calcium lactate pentahydrate Ca(C3H5O3)2⋅5H2O and monocalcium phosphate monohydrate Ca(H2PO4)2⋅H2O were treated in an aqua medium in mechanical activation conditions to prepare powder mixtures with preset molar ratios Ca/P containing calcium hydrophosphates with Ca/P = 1 (precursors of calcium pyrophosphate Ca2P2O7). These powder mixtures containing calcium hydrophosphates with Ca/P = 1 and non-reacted starting salts were heat-treated at 600 °C after drying and disaggregation in acetone. Phase composition of all powder mixtures after heat treatment at 600 °C was presented by γ-calcium pyrophosphate γ-Ca2P2O7 according to the XRD data. The addition of more excess of monocalcium phosphate monohydrate Ca(H2PO4)2·H2O (with appropriate molar ratio of Ca/P = 1) to the mixture of starting components resulted in lower dimensions of γ-calcium pyrophosphate (γ-Ca2P2O7) individual particles. The grain size of ceramics increased both with the growth in firing temperature and with decreasing molar ratio Ca/P of powder mixtures. Calcium polyphosphate (t melt = 984 °C), formed from monocalcium phosphate monohydrate Ca(H2PO4)2⋅H2O, acted similar to a liquid phase sintering additive. It was confirmed by tests in vitro that prepared ceramic materials with preset molar ratios Ca/P = 1, 0.975, and 0.95 and phase composition presented by β-calcium pyrophosphate β-Ca2P2O7 were biocompatible and could maintain bone cells proliferation.

Synthesis of soluble calcium compound from skipjack tuna bones using edible weak acids

This study aimed to enhance the water solubility of calcium from tuna (Katsuwonus pelamis) bones (TB). Calcium hydroxyapatite (HA) was obtained by calcination of TB. For mineral profiles of TB and HA, Ca had the highest content followed by P with Ca/P of 3.47 and 1.94. Mg, K, and Na as macro minerals and Cr, Cu, Mn, and Zn as micro minerals were also found. Subsequently, HCl was applied to form structured HA-chloride compound (HA-Cl) then reacted with alkaline to obtain structured HA-hydroxide compound (HA-OH). In order to enhance the water solubility, citric and lactic acid were individually reacted with HA-Cl and HA-OH to obtain structured HA-citrate compounds (HA-Cl-Ci and HA-OH-Ci) and structured HA-lactate compounds (HA-Cl-Lac and HA-OH-Lac). HA-Cl-Ci had the highest water solubility (93.34 ± 0.45%) followed by HA-OH-Lac (90.35 ± 0.23%) with Ca/P ratio of 2.28 and 2.24, respectively. HA-Cl-Ci and HA-OH-Lac demonstrated the similar mineral profiles to those of HA but with different contents. The results of FT-IR indicated the carboxyl group of acid played an important role in binding Ca2+. X-ray diffractograms indicated that calcined bone was HA whereas the major composition of HA-Cl-Ci and HA-OH-Lac was related to calcium citrate tetrahydrate and calcium lactate pentahydrate, respectively.

Shelf-Life Evaluation of Ingredient Combinations and Technologies for Use in Pet Food Formulations.

Simple SummaryCreation of new meat-based pet food and pet treats continues to grow at a steady annual rate within the pet food industry. Poultry co-products are often overlooked due to their poor quality and low customer acceptance. However, poultry co-products pose great potential and added value to the pet food industry. Two of the most common poultry co-products (wooden breast and carcass frames) often directed towards pet food were used in a fresh pet food formulation. Due to variations in meat quality because of the wooden breast and carcass frames, a hydrocolloid was utilized to improve fresh pet food characteristics. A hydrocolloid is a type of protein that when added to meat products aids with binding and stabilization of the pet food. For the current study, the combination of sodium alginate and encapsulated calcium lactate pentahydrate (ALGIN) was used. Due to the perceived poor quality of wooden breast and carcass frames, it is plausible that the addition of hydrocolloids can combat the undesirable characteristics. Results from the current study suggest that the impact of ALGIN in poultry co-product pet food combinations does not severely alter shelf-life characteristics of a fresh pet food. However, the inclusion of varying amounts of wooden breast and ground carcass frame can impart a greater impact on shelf-life characteristics in fresh pet food by altering surface color and lipid oxidation.Poultry co-product chicken frames (CF) and wooden breast (WB) along with ingredient technology use may bring enhanced value to the pet food industry. Therefore, the current study focused on evaluating CF and WB combinations along with sodium alginate and encapsulated calcium lactate pentahydrate (ALGIN) inclusion within a fresh pet food formulation under simulated shelf-life conditions. Fresh chicken frames (CF) and boneless-skinless wooden breast (WB) were ground and allocated randomly to one of ten treatment combinations with either 0.5 or 1.0% added ALGIN. Ground treatments were placed into a form and fill vacuum package and stored using a reach-in refrigerated case for 21 days. Packages were evaluated for instrumental surface color, lipid oxidation, water activity, and pH on days 1, 3, 7, 14 and 21 of the display. Packages of pet food were lighter, less red, and more yellow (p < 0.05) with increasing percentages of CF regardless of ALGIN inclusion, whereas pH was greater (p < 0.05) and lipid oxidation was less (p < 0.05) with increasing percentage of WB. Water activity increased (p < 0.05) when WB and ALGIN inclusion increased. The current results suggest that the use of ALGIN in a poultry co-product pet food formulation can improve shelf-life characteristics such as surface color and lipid oxidation in fresh pet food.

The Synthesis of Hydroxyapatite by Hydrothermal Process with Calcium Lactate Pentahydrate: The Effect of Reagent Concentrations, pH, Temperature, and Pressure.

Hydroxyapatite and other calcium phosphates in the form of whiskers are lately widely considered as fillers for biocomposites due to their special biological and reinforcing properties. Depending on the method of synthesis, apatite whiskers of various sizes and phase composition can be obtained. In our work, hydroxyapatite (HAp) whiskers were successfully prepared in reaction between calcium lactate pentahydrate and orthophosphoric acid. The advantage of the proposed technique is the simple but precise control of the HAp crystal morphology and high product purity which is necessary for biomedical applications. The effect of reagent concentrations, pH, reaction temperature, and pressure on HAp whiskers' morphology and composition was investigated. In the result, we obtained hydroxyapatite of different morphology such as whiskers, hexagonal rods, and nanorods. The products were characterized by SEM, XRD, and FTIR. In this work, the synthesis of HAp whiskers by direct decomposition of calcium lactate pentahydrate chelates under hydrothermal conditions was showed for the first time.

Thermal degradation of calcium lactate pentahydrate using TGA/FTIR/MS: thermal kinetic and thermodynamics studies

ABSTRACT The objective of this study is to investigate the thermal degradation kinetics and thermodynamics of the calcium lactate pentahydrate (CLP) crystals by means of a thermogravimetric analyzer (TGA) at four different heating rates from 25°C to 1000°C in N2 atmosphere. First, the CLP crystals were precipitated at pH 6 and 25°C in a batch-type crystallizer and the obtained crystals were characterised by X-ray powder diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The XRD result showed that the calcium l-lactate pentahydrate (L-CLP) was the only crystalline phase produced. Then, the activation energy and pre-exponential factor of thermal degradation were determined based on the Coats–Redfern, Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Starink models. The degradation reaction order was determined as 1.5 by Coats-Redfern model. The average activation energy of the CLP was 34.7, 33.0, and 33.3 kJ/mol for the FWO, KAS, and Starink models, respectively. Thermodynamic parameters as changes in enthalpy, entropy and Gibbs free energy were calculated depending on the conversion degree. Finally, TGA in combination with FTIR and mass spectrometer (MS) was utilised to detect the evolved gases during the degradation of CLP. H2O and CO2 were identified as the main evolved products.

Bacteria incorporated with calcium lactate pentahydrate to improve the mortar properties and self-healing occurrence

Concrete can be harmful to the environment due to its high energy consumption and CO2 emission and also has a potential crack formation, which can promote a drop in its strength. Therefore, concrete is considered as a non-sustainable material. The mechanisms by which bacterial oxidation of organic carbon can precipitate calcite that may fill the voids and cracks on cement-based materials have been extensively investigated to prevent and heal the micro-cracks formation. Hence, this study focused on utilizing a new alkaliphilic bacterial strain indigenous to an Indonesian site, Lysinibacillus sphaericus strain SKC/VA-1, incorporated with calcium lactate pentahydrate, as a low-cost calcium source, with various bacterial inoculum concentrations. The bacterium was employed in this study due to its ability to adapt to basic pH, thus improving the physical properties and rejuvenating the micro-cracks. Experimentally, the addition of calcium lactate pentahydrate slightly affected the mortar properties. Likewise, bacteria-incorporated mortar exhibited an enhancement in the physical properties of mortar. The highest improvement of mechanical properties (an increase of 45% and 36% for compressive and indirect tensile strength, respectively) was achieved by the addition of calcium lactate pentahydrate incorporated with 10% v/v bacterial inoculum [about 7 × 107 CFU/ml (colony-forming unit/ml)]. The self-healing took place more rapidly on bacterial mortar supplemented with calcium lactate pentahydrate than on the control specimen. XRD analysis demonstrated that the mineralogical composition of self-healing precipitates was primarily dominated by calcite (CaCO3), indicating the capacity of L. sphaericus strain SKC/VA-1 to precipitate calcite through organic carbon oxidation for self-healing the artificial crack on the mortar. To our knowledge, this is the first report on the potential utilization of the bacterium L. sphaericus incorporated with calcium lactate pentahydrate to increase the mortar properties, including its self-healing ability. However, further study with the water-cement ratio variation is required to investigate the possibility of using L. sphaericus and calcium lactate pentahydrate as an alternative method rather than reducing the water-cement ratio to enhance the mortar properties.

Solid State Stability and Preformulation Studies for Acetylcholinesterase Inhibitor Drug Tacrine

In this paper, the acetylcholinesterase inhibitor drug tacrine was investigated by two complementary instrumental techniques, namely infrared spectroscopy and thermal analysis, as pure drug and in solid binary mixtures with nine excipients frequently used in the pharmaceutical industry, namely starch, sodium carboxymethyl cellulose, polyvinylpyrrolidone K30, fumed silica (Aerosil), talc, anhydrous lactose, magnesium stearate, mannitol and calcium lactate pentahydrate. The corroboration of obtained data by the two complementary methods confirmed the incompatibility of this drug with anhydrous lactose, mannitol, magnesium stearate and calcium lactate under both ambient conditions and thermal stress, and thermally induced interactions between tacrine and silica. In the development of new generic solid formulations, four of the investigated excipients (i.e., starch, sodium carboxymethyl cellulose, polyvinylpyrrolidone K30 and talc) can be used, since they are compatible with tacrine under ambient conditions as well as under thermal stress.

Comparative performance of different bacteria immobilized in natural fibers for self-healing in concrete

Carrier compounds besides the type of bacteria for microbial induced calcite precipitation are equally important in self-healing concrete. This study investigates the potential utilization of natural fibers namely, coir, flax, and jute fibers to carry bacterial spores for self-healing in concrete. The comparison is drawn for introducing calcite precipitation bacteria namely Bacillus subtilis KCTC-3135T, Bacillus cohnii NCCP-666, and Bacillus sphaericus NCCP-313 in concrete along with calcium lactate pentahydrate and urea as organic nutrients. The findings from visual, microstructural, and mechanical properties of self-healing concrete suggest that natural fibers were capable of substantial immobilization potential for bacterial spores. Flax fibers provided better protection to bacteria with improved crack-healing and regain in compressive strength, whereas coir fibers resulted in higher compressive strength. It is also observed that B. sphaericus NCCP-313 precipitated more calcium carbonate as a healing product with uniform healing in the entire length of cracks in concrete. Consequently, approximately 75–85% and 60–65% healing rates were attained by fiber immobilized bacteria in 7 days and 28 days pre-cracked specimens, respectively.

Stability and Compatibility Studies of Levothyroxine Sodium in Solid Binary Systems-Instrumental Screening.

The influence of excipients on the stability of sodium levothyroxine pentahydrate (LTSS) under ambient conditions and thermal stress was evaluated. Since LTSS is a synthetic hormone with a narrow therapeutic index, the interactions of LTSS with excipients can lead to a drastic diminution of therapeutic activity. Ten commonly used pharmaceutical excipients with different roles in solid formulations were chosen as components for binary mixtures containing LTSS, namely, starch, anhydrous lactose, D-mannitol, D-sorbitol, gelatin, calcium lactate pentahydrate, magnesium stearate, methyl 2-hydroxyethyl cellulose (Tylose), colloidal SiO2 (Aerosil) and talc. As investigational tools, universal attenuated total reflectance- Fourier transform infrared spectroscopy UATR-FTIR spectroscopy and thermal analysis were chosen and used as follows: UATR-FTIR spectra were drawn up for samples kept under ambient conditions, while thermoanalytical tools (TG/DTG/HF data) were chosen to evaluate the inducing of interactions during thermal stress. The corroboration of instrumental results led to the conclusion that LTSS is incompatible with lactose, mannitol and sorbitol, and these excipients should not be considered in the development of new generic solid formulations.

Selection of bacteria inducing calcium carbonate precipitation for self-healing concrete application

A modification of bacterial medium using calcium lactate pentahydrate was developed for calcium carbonate precipitation. A total of five strains of bacteria were cultivated on the solution medium containing nutrient broth and calcium lactate pentahydrate. In this study, the variation of 3.2 mM and 16.2 mM of calcium lactate pentahydrate was used to obtain the optimum condition for bacterial growth. The results showed that isolated strains CPB 1, CPB 3, and CPB 5 with medium containing nutrient broth and 3.2 mM calcium lactate pentahydrate gave the optimum growth, pH and Eh, thus being favourable for the process of calcium carbonate precipitation. Hence, this will be useful for self-healing concrete.

Calcium Lactate Pentahydrate Crystallization in the Presence of Pentanoic Acid

AbstractCalcium lactate crystallization was investigated in the presence of pentanoic acid in a mixed‐suspension mixed‐product removal (MSMPR)‐type crystallizer. Filtration rate measurements were carried out to define the effect of pentanoic acid on the filtration characteristics of calcium lactate pentahydrate crystals. The average particle size, length‐to‐width ratio, and morphologies of calcium lactate pentahydrate crystals were also determined and examined as a function of pentanoic acid concentrations. The zeta potential of calcium lactate pentahydrate crystals was measured. Thermogravimetric and differential thermal analysis (TGA‐DTA) as well as X‐ray diffraction (XRD) were performed and Coats and Redfern's method was used to verify the kinetic parameters in the dehydration steps observed in the TGA curves.

Effect of the Amino Acids L‐Methionine and D‐Threonine on Calcium Lactate Pentahydrate Crystallization

AbstractThe crystallization of calcium lactate pentahydrate was performed in the absence and presence of the amino acids L‐methionine and D‐threonine. The metastable zone width was measured as a function of concentration of amino acids and cooling rate. Fourier transform infrared (FTIR) analysis, scanning electron microscopy (SEM), filtration rate, and average particle size measurements were performed. FTIR results showed that all crystals formed in calcium L‐lactate pentahydrate form, but crystals, which had a needle‐like crystal structure in pure media, experienced a habit change in the presence of amino acids. The average particle size and the length‐to‐width ratio of the crystals increased in the presence of amino acids which appeared as reduction in mean specific cake resistance. The amino acids exerted enlargement effects on the metastable zone width.

Powder X-ray diffraction can differentiate between enantiomeric variants of calcium lactate pentahydrate crystal in cheese

Powder X-ray diffraction has been used for decades to identify crystals of calcium lactate pentahydrate in Cheddar cheese. According to this method, diffraction patterns are generated from a powdered sample of the crystals and compared with reference cards within a database that contains the diffraction patterns of known crystals. During a preliminary study of crystals harvested from various Cheddar cheese samples, we observed 2 slightly different but distinct diffraction patterns that suggested that calcium lactate pentahydrate may be present in 2 different crystalline forms. We hypothesized that the 2 diffraction patterns corresponded to 2 enantiomeric forms of calcium lactate pentahydrate (l- and dl-) that are believed to occur in Cheddar cheese, based on previous studies involving enzymatic analyses of the lactate enantiomers in crystals obtained from Cheddar cheeses. However, the powder X-ray diffraction database currently contains only one reference diffraction card under the title “calcium lactate pentahydrate.” To resolve this apparent gap in the powder X-ray diffraction database, we generated diffraction patterns from reagent-grade calcium l-lactate pentahydrate and laboratory-synthesized calcium dl-lactate pentahydrate. From the resulting diffraction patterns we determined that the existing reference diffraction card corresponds to calcium dl-lactate pentahydrate and that the other form of calcium lactate pentahydrate observed in cheese crystals corresponds to calcium l-lactate pentahydrate. Therefore, this report presents detailed data from the 2 diffraction patterns, which may be used to prepare 2 reference diffraction cards that differentiate calcium l-lactate pentahydrate from calcium dl-lactate pentahydrate. Furthermore, we collected crystals from the exteriors and interiors of Cheddar cheeses to demonstrate the ability of powder X-ray diffraction to differentiate between the 2 forms of calcium lactate pentahydrate crystals in Cheddar cheeses. Powder X-ray diffraction results were validated using enzymatic assays for lactate enantiomers. These results demonstrated that powder X-ray diffraction can be used as a diagnostic tool to quickly identify different forms of calcium lactate pentahydrate that may occur in Cheddar cheese.

In situ Evaluation of the Erosive Potential of Orange Juice Modified by Food Additives

The aim of this study was to evaluatethe erosive potential of orange juice modified with food-approved additives: 0.4 g/l of calcium (Ca) from calcium lactate pentahydrate, 0.2 g/l of linear sodium polyphosphate (LPP) or their combination (Ca+LPP) were added to a commercially available orange juice (negative control, C–). A commercially available calcium-modified orange juice (1.6 g/l of calcium) was the positive control (C+). These juices were tested using a short-term erosion in situmodel, consisting of a five-phase, single-blind crossover clinical trial involving 10 subjects. In each phase, subjects inserted custom-made palatal appliances containing 8 bovine enamel specimens in the mouth and performed erosive challenges for a total of 0 (control), 10, 20, and 30 min. Two specimens were randomly removed from the appliances after each challenge period. Enamel surface microhardness was measured before and after the clinical phase and the percentage of surface microhardness change (%SMC) was determined. Before the procedures, in each phase, the subjects performed a taste test, where the juice assigned to that phase was blindly compared to C–. Overall, C+ showed the lowest %SMC, being the least erosive solution (p < 0.05), followed by Ca+LPP and Ca, which did not differ from each other (p > 0.05). LPP and C– were the most erosive solutions (p < 0.05). Taste differences were higher for C+ (5/10 subjects) and Ca (4/10 subjects), but detectable in all groups, including C– (2/10 subjects). Calcium reduced the erosive potential of the orange juice, while no protection was observed for LPP.

Effects of calcium salts on thermal characteristics of hydroxypropyl methylcellulose films

Cast films comprising hydroxypropyl methylcellulose (HPMC) and calcium chloride (CaCl 2) have higher flexibility than those with HPMC and calcium lactate pentahydrate (CLP). The aim of the present study was to investigate the relationship between the molecular behaviour and the film flexibility of HPMC cast films. In differential scanning calorimetry (DSC) measurements, the HPMC-only cast films exhibited a glass transition temperature (Tg) of 142.1–143.9 °C, which is similar that of HPMC/CLP cast films. In contrast, HPMC/CaCl 2 cast films exhibited Tg of 76.1–77.3 °C, which is lower than that of HPMC-only and HPMC/CLP films. Thermal mechanical analysis (TMA) results indicated that the HPMC-only and HPMC/CLP cast films contracted strongly around the Tg calculated using DSC. In contrast, the cast films comprising HPMC/CaCl 2 blends gradually contracted as the temperature increased; this behaviour is significantly different from that observed in the HPMC-only and HPMC/CLP films. The most probable mechanism for the film flexibility of HPMC/calcium salt blends was clarified through attenuated total reflection Fourier transform-infrared (ATR FT-IR) and thermogravimetric (TG) analysis. The analysis results suggest that the difference in the flexibility of the cast films in the presence of CaCl 2 or CLP depends on the difference affinity between calcium salts and water molecules.