Efficient synthesis of rare sugars from galactose in hot compressed water using eggshells as an environmentally friendly catalyst.

Aqueous galactose solutions containing eggshell was heated at 120 °C to produce calcium supplements containing rare sugars. Galactose was isomerized to rare sugars with improving rare sugar yields compared to those without eggshell. Organic acids were also formed as byproducts during the reaction. These acids were neutralized by dissolving eggshells with increasing the calcium ion concentration in the solution. When eggshell components (calcium carbonate, magnesium carbonate, or calcium phosphate) were used for the treatment, rare sugars were also formed. Especially, addition of magnesium carbonate improved rare sugar yield, but byproduct formation became more pronounced. Eggshells used in the treatment were used for repeated treatments. When eggshells were used three times, rare sugar yield changed only slightly but the selectivity of rare sugars improved significantly. By these processes, we obtained an aqueous solution of rare sugars containing calcium ion at 295 mg/L, which has potential as ingredients for dietary supplements.

Optimal index for detecting splenic involvement on 18F-fluorodeoxyglucose positron emission tomography/computed tomography imaging in diffuse large B-cell lymphoma.

Accurate clinical staging is important in diffuse large B-cell lymphoma (DLBCL) to adapt to optimal therapy. Splenic involvement of DLBCL has been recently more detectable with the advancement of a diagnostic scan by 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT). Our clinical question is whether splenic involvement was adequately diagnosed by FDG-PET/CT imaging. This retrospective study aimed to determine the optimal index for evaluating splenic involvement in patients with DLBCL. Patients with newly diagnosed DLBCL who were examined with FDG-PET/CT at diagnosis and the end of induction chemotherapy (EOI) was enrolled. The splenic involvement with the splenic FDG uptake value higher than that of the liver at diagnosis or with the decrease of splenic uptake at EOI by visual evaluation was evaluated as positive. The calculative evaluation of splenic involvement, based on the data of standardized uptake value (SUV) of the spleen, used maximum SUV (SUVmax), mean SUV (SUVmean), spleen total lesion glycolysis (spleen TLG), and spleen length. A change in each index following induction chemotherapy was expressed as an index. Receiver operating characteristic analysis was used to set the cutoff value for each index. This study included 52 patients. Spleen TLG (0.904) showed the best accuracy, followed by SUVmax (0.885) and SUVmean (0.885), among the 5 indexes for splenic involvement at diagnosis. Splenic involvement was predicted with a higher accuracy level (0.923) when selecting the cases with values higher than the cutoff level on both spleen TLG and SUVmax. The decision at EOI was more suitable by selecting both positive cases of ∆ TLG and ∆ SUVmax. Obtaining both the positive spleen TLG and SUVmax is recommended at diagnosis to predict splenic involvement. The assessment by ∆ spleen TLG and ∆ SUVmax seems to be optimal.

Isomerization and epimerization of fructose in phosphate buffer under subcritical water conditions.

Isomerization and epimerization of fructose to glucose, mannose, allulose, and allose were executed using a subcritical phosphate buffer solution to effectively produce useful monosaccharides. The conversion of the substrate and the yield of products were dependent on the reaction temperature, initial pH, initial substrate concentration, and buffer concentration. A high yield of mannose was achieved under the optimal reaction conditions we identified. We subsequently performed the kinetic analysis based on the proposed reaction network, and evaluated the effects of temperature and pH on the reactions. We then estimated the apparent activation energy values for each reaction.

Isomerization and epimerization of glucose and galactose in arginine solution and phosphate buffer under subcritical fluid conditions.

Reaction of glucose or galactose was performed in arginine solution or phosphate buffer (pH 7.0) using a batch reactor at 110°C. The yields of products, pH, and absorbances at 280 and 420 nm were measured during the reaction. Fructose, mannose, and allulose were formed from glucose; tagatose, talose, and sorbose were done from galactose. The reaction proceeded more rapidly in arginine solution than in phosphate buffer. In arginine solution, yields of fructose and tagatose were 20% and 16%, respectively, after 30-min reaction; in phosphate buffer, they were 14% and 10%, respectively. However, in both reaction media, the pH drop and increase in absorbances continued even after the yield became almost constant. The absorbance increased particularly in the latter half of the reaction due to formation of browning products. Therefore, to avoid browning, the reaction should be stopped as soon as possible after the yield approaches its maximum value.

Isomerization of galactose to tagatose using arginine as a green catalyst.

This work investigated the isomerization of galactose to tagatose, a low caloric rare sugar, using arginine as a catalyst. Galactose (5 % w/v) and arginine (0.10 mol/mol-galactose) in water were treated at 90-120 °C. The results showed that as the temperature and time increased, galactose was continuously consumed. Rare sugars namely tagatose, talose, and sorbose were formed with the highest yield of 16.8, 2.7, and 3.3 %, respectively at 120 °C, 20 min. High temperature and short time conditions resulted in lower Maillard reaction extent. The arginine concentrations at 0.05, 0.10, and 0.15 mol/mol-galactose resulted in a slight increase in tagatose yield while an increase of the initial galactose concentration from 5 to 20 % resulted in a decrease in tagatose yield, although the tagatose concentration increased. The highest tagatose productivity of 278 g/(L⋅h) was obtained using galactose of 20 % w/v and arginine of 0.10 mol/mol-galactose at 120 °C and 4 min.

Effect of Oil-Droplet Diameter on Lipid Oxidation in O/W Emulsions.

The effect of oil-droplet diameter on lipid oxidation in O/W emulsions is unclear, and conflicting results have been reported. These conflictions may be due to different experimental conditions being used, such as the type of oil, the type of emulsifier, temperature, and the range of oil-droplet diameters tested. The method used to evaluate the oxidation could also have varied among studies. In O/W emulsions, oxygen dissolved in the aqueous phase is transferred to the oil phase through the oil-water interface and is consumed in the oil phase by oxidation. Therefore, the effect of the oil-droplet diameter on the lipid oxidation rate was evaluated by simultaneously solving the mass balance equations of oxygen and oil in the oil phase. The simulation showed that the oil-droplet diameter does not affect the lipid oxidation rate in O/W emulsions with oil-droplet diameters on the order of micrometers or less because the oxidation reaction itself is rate-limiting.

Kinetic analysis of thermal degradation of betanin at various pH values using deconvolution method.

Although betanin is commonly used as a water-soluble red colorant in foods, it is unstable when heated. In this study, the discoloration of betanin in a buffer solution was kinetically studied in the pH range of 2.6 to 7.6 at 40 °C to 80 °C. The absorption spectrum of betanin was deconvoluted into the spectra of betanin and its degradation product, betalamic acid. Subsequently, a reversible consecutive reaction, in which betanin was reversibly degraded to betalamic acid, and betalamic acid was further degraded, was assumed to calculate the first-order rate constant of each step. The apparent reaction mechanism varied depending on the pH values. Based on these rate constants, the activation energy of each process, as well as the equilibrium constant and enthalpy change for the reversible reaction between betanin and betalamic acid were evaluated.

Interdependent Oxidation of Eicosapentaenoic Acid and Docosahexaenoic Acid in Isada Krill Oil Encapsulated with Maltodextrin by Spray-drying.

The major polyunsaturated fatty acids in krill oil extracted from Euphausia pacifica, known as Isada on the Sanriku coast, are eicosapentaenoic acid (EPA) and docosahexaenoic (DHA) acid. A kinetic model was proposed to explain the relationship between the fractions of unoxidized EPA (Y E) and unoxidized DHA (Y D) in the oil spray-dried with maltodextrin and stored at 25, 50, and 70℃. The relationship between Y E and Y D during storage was independent of the temperature and could be expressed using the proposed model. This indicated that the oxidation of EPA and DHA in krill oil was interdependent.

Solubility and mass transfer coefficient of oxygen through gas- and water-lipid interfaces.

The solubility of oxygen and its transfer rate to the lipid phase play important roles in lipid oxidation, which affects the taste and safety of lipid-containing foods. In this study, we measured the Henry's constants (solubility) of oxygen for fatty acids, fatty acid esters, and triacylglycerols (TAGs; vegetable oils), as well as the mass transfer coefficients of oxygen at the gas- and water-lipid interfaces. The constants and coefficients were estimated by analyzing the change over time in the oxygen partial pressure or concentration in the closed container based on the mass balance equations of oxygen in the gas and liquid phases. The constant for water obtained by the method used in this study was in agreement with the previously reported value to confirm the validity of the method. The constants for lipids depended on the lipid type, and were higher in the order of fatty acid ester, fatty acid, and TAG. That is, the solubility of oxygen decreased in this order. For all lipids, the constant increased as the number of carbon atoms in the fatty acid chain increased. The constants for fatty acids and their esters were linearly correlated with the enthalpies of evaporation of the lipids. The mass transfer coefficients of oxygen at the gas-liquid interface were on the order of 10-5 m/s for water and methyl dodecanoate and of 10-6 m/s for TAG (rapeseed oil). The coefficient at the water-lipid interface was on the order of 10-6 m/s. PRACTICAL APPLICATION: The Henry's constants (solubility) and transfer rate of oxygen to the lipid phase, fatty acids, fatty acid esters, and triacylglycerols (TAG) were measured. The lipids solubilized three to five times more oxygen than water, and mass transfer rate of oxygen at gas- and water-lipid interfaces were almost same. The constants for fatty acids and fatty acid esters were linearly correlated to their enthalpies of evaporation, and this correlation is expected to be useful for estimating the Henry's constants for other fatty acids and their esters.

Production of tagatose and talose through isomerization of galactose in a buffer solution under subcritical water conditions.

Galactose was isomerized in pure water or in 10 mmol/L sodium phosphate buffer at 160 °C under pressurized conditions. The isomerization of galactose to tagatose and talose in phosphate buffer resulted in 14% and 1.4% yields, respectively, which were significantly higher than those obtained in subcritical pure water (0.6% and <0.1%, respectively). The effect of the temperature on isomerization was examined between 100 and 160 °C. The most remarkable isomerization was observed at 120 °C or higher. The effect of the buffer solution type was also examined. The pH drop of the treated solution was lesser in MOPS and PIPES buffers than in the phosphate buffer; however, the isomerization was less likely to occur in MOPS and PIPES buffers. The relationship between the pH drop during the reaction in phosphate buffer and the yields of tagatose and talose revealed that the isomerization proceeded only when the pH was >6.3. Our results indicate that the galactose isomerization by Lobry de Bruyn-Alberda-van Ekenstein transformation rarely occurred at low pH due to the formation of organic acids.

Analysis of Nonisothermal Crystallization of Rapeseed Oil by Deconvolution of Differential Scanning Calorimetry Curve.

Crystallization of vegetable oil affects the efficiency of the oil-refining process and the quality of foods containing the oil. However, the crystallization of the oil is a complicated phenomenon. The crystallization behavior of rapeseed oil was investigated using differential scanning calorimetry (DSC) at a cooling rate of 0.5-10°C/min. It was found that multiple crystal structures with a metastable crystal formed at high cooling rates. A deconvolution technique was applied to analyze kinetically the DSC curves with some peaks. Each DSC curve was separated into 3-5 peaks fitted with an asymmetric double sigmoid function and a Lorentz one. Each peak was normalized by its integrated value, and the crystallinity was calculated. Using the crystallinity values, Avrami, Ozawa, and Friedman plots were obtained. The cooling rate was found to affect the crystallization mechanism and triacylglycerol (TAG) composition of the crystal in the separated peak. Even if the peak numbers are the same, the TAG composition of the crystals might be different depending on the cooling rate. Judging from the peak top temperature and area of the separated peaks, trioleoyl glycerol and 1,2-dilinolenyl-3-linoleyl glycerol would be included in crystals in the peaks with the largest and lowest peak top temperatures, respectively. The relationship between the peak top temperature and cooling rate was unique. This suggests that the crystallization behavior during isothermal storage was different from that in a nonisothermal process.

Effects of Sodium Chloride and Acetic Acid Concentrations on Dispersion Stability of Mayonnaise.

Mayonnaise is an oil-in-water (O/W) emulsion containing oil at the weight fraction of about 70%, which is stable for over a year when stored at room temperature. The stability examination of more stable mayonnaise can be time-consuming. Mayonnaise rapidly separates into oil and aqueous phases when water in the mayonnaise evaporates, which increases the ionic strength of the aqueous phase and reduces electrostatic repulsion among oil droplets. Simulating this phenomenon under reduced pressure, the stability of mayonnaises with different sodium chloride concentrations [0, 1, 3, 5 or 8% (kg/kg-aqueous phase)] and acetic acid concentrations [0, 1, 5, 10, 15 or 20% (kg/kg-acetic acid solution)] was evaluated by comparing the duration of time before each mayonnaise sample separated into oil and aqueous phases. The durations (destabilization times) correlated with the sodium chloride concentrations for mayonnaises with 1% (kg/kg-acetic acid solution) acetic acid solution. Destabilization times were independent of the sodium chloride concentration, however, for mayonnaises with greater than 10% (kg/kg-acetic acid solution) acetic acid solution. The differences in destabilization times were ascribed to denaturation of egg yolk granules. The destabilization time of commercially available mayonnaise can be similarly explained. The results of this study, which showed that the increase in the ionic strength of the aqueous phase by evaporation assessed the stability of mayonnaise in expedition way, were consistent with previously reported findings.

Induction Periods for Lipid Crystallization of Various Vegetable Oils.

The induction period for crystallization, defined as the time required to crystallize, was discussed during isothermal storage at -5 to -45°C for various vegetable oils; olive, safflower, rapeseed, corn, rice bran, soybean, and linseed oils. The induction periods, largely dependent on the oil type and storage temperature, were classified into two groups. The induction periods of corn, rice bran, soybean, and linseed oils were monotonically shortened as the storage temperature decreased. On the other hand, the induction periods for rapeseed, olive, safflower oils and the mixtures of rapeseed and soybean oils, and of olive and safflower oils did not simply change or elongate with a decrease in storage temperature. The induction periods could be formulated using two parameters. One was an expected value of the melting point of the oil, which was calculated from its fatty acid composition. The other was a molar fraction of triacylglycerol composed of the same fatty acids in the oil. The crystallization and melting processes of the oils under nonisothermal conditions were also analyzed by differential scanning calorimetry (DSC). It was suggested that the induction period was also predictable from the peak shape, peak number, onset temperature, and peak area in the DSC curve of the oil during the crystallization process.

Astaxanthin stability and color change of krill during subcritical water treatment.

Pacific krill (Euphausia pacifica) contains high amounts of astaxanthin, a carotenoid pigment with strong antioxidative activities. In this study, the effects of subcritical water temperatures (100-180 °C) and times (0-10 min) on color changes (L*, a*, and b*) and astaxanthin degradation in Pacific krill were investigated. In addition, an aqueous solution of pure astaxanthin and that of crude astaxanthin from Pacific krill, both at a concentration of 5 mg/L, were subjected to treatment under subcritical water conditions using a flow-type reactor to compare the degradation of free astaxanthin and astaxanthin fatty acid esters. To compare the results of the different treatment conditions on the properties of astaxanthin, the severity factor (log R0) was calculated, which ranged from 0.38 to 3.52. The extractability of astaxanthin enhanced when the subcritical water treatment was carried out at log R0 values of 2.00-2.44. In contrast, astaxanthin underwent 50% degradation at log R0 > 2.44. The changes in the a* values correlated well with the astaxanthin content in the treated krill, while the b* and L* values might relate to the browning components forming owing to Maillard reaction. The results show that free astaxanthin was less stable than crude astaxanthin under subcritical water treatment.

Dispersion Stability of O/W Emulsions with Different Oil Contents Under Various Freezing and Thawing Conditions.

Freezing and thawing of oil-in-water (O/W) emulsion-type foods bring about oil-water separation and deterioration; hence, the effects of freezing and thawing conditions on the destabilization of O/W emulsions were examined. The freezing rate and thawing temperature hardly affected the stability of the O/W emulsion. O/W emulsions having different oil fractions were stored at temperatures ranging from -30 to -20 °C and then thawed. The stability after thawing depended on the storage temperature, irrespective of the oil fraction of the emulsion. A good correlation was found between the time at which the stability began to decrease and the time taken for the oil to crystalize. These results indicated that the dominant cause for the destabilization of the O/W emulsion during freezing and thawing is the crystallization of the oil phase and that the effects of the freezing and thawing rates on the stability are insignificant.

Effect of oil droplet size on the oxidative stability of spray-dried flaxseed oil powders.

The effect of the size of oil droplets on the oxidative stability of flaxseed oil in spray-dried powders was investigated. Maltodextrin with a dextrose equivalent of 25 was used as a wall material, and sodium caseinate and transglutaminase-polymerized sodium caseinate were used as emulsifiers. The oxidative stability of flaxseed oil encapsulated in the spray-dried powders was evaluated using lipid oxidation and conductometric determination tests at 105 °C. The powders containing larger oil droplets exhibited higher surface oil content after spray drying, and higher peroxide value and conductivity after storage at 105 °C. Removal of the surface oil from the powders by washing with hexane significantly decreased the conductivity. The results indicated that the surface oil of the spray-dried flaxseed oil powders affected the oxidation stability.

Dispersion and oxidative stability of O/W emulsions and oxidation of microencapsulated oil.

Oil-in-water (O/W) emulsions are among the dispersion systems commonly used in food, and these emulsions are in thermodynamically unstable or metastable states. In this paper, various methods for preparing O/W emulsions are outlined. Since the commodity value of food is impaired by the destabilization of O/W emulsions, experimental and theoretical approaches to assess the stability of O/W emulsions are overviewed, and factors affecting the dispersion stability of emulsions are discussed based on the DLVO theory and the concept of the stability factor. The oxidation of lipids in O/W emulsions is unhealthy and gives rise to unpleasant odors. Factors affecting the autoxidation of lipids are discussed, and theoretical models are used to demonstrate that a reduction of the oil droplet size suppresses or retards autoxidation. Microencapsulated lipids or oils exhibit distinct features in the oxidation process. Models that explain these features are described. It is demonstrated that a reduction in the oil droplet size is also effective for suppressing or retarding the oxidation of microencapsulated oils.

Distribution of saccharides and salts on amphoteric ion-exchange resin.

An amphoteric ion-exchange resin hardly shrank in 550 and 300 g/L glucose and sodium chloride solutions, respectively; however, the bed packed with a cation-exchange resin shrank considerably. From the distribution coefficients of some saccharides, the swelling pressure of the amphoteric ion-exchange resin was estimated to be 2.0 MPa at 25 °C. The distribution coefficients of glucose, galactose, fructose, and mannose were independent of their concentration and were about 0.621. On the other hand, the apparent distribution coefficients of NaF, NaCl, NaBr, NaI, LiCl, KCl, and CsCl largely depended on concentration. A model for the distribution of salts on the amphoteric resin was proposed, assuming an interaction between the anion of the salt and the positively charged fixed ions with binding constant B. The B values of the chloride salts were nearly the same (1.69-2.94 L/mol), while the values of the sodium salts were largely different depending on the anion.

Effect of different dextrose equivalents of maltodextrin on oxidation stability in encapsulated fish oil by spray drying.

Encapsulating fish oil by spray drying with an adequate wall material was investigated to determine if stable powders containing emulsified fish-oil-droplets can be formed. In particular, the dextrose equivalent (DE) of maltodextrin (MD) affects the powder structure, surface-oil ratio, and oxidative stability of fish oil. The carrier solution was prepared using MD with different DEs (DE = 11, 19, and 25) and sodium caseinate as the wall material and the emulsifier, respectively. The percentage of microcapsules having a vacuole was 73, 39, and 38% for MD with DE = 11, 19, and 25, respectively. Peroxide values (PVs) were measured for the microcapsules incubated at 60 °C. The microcapsules prepared with MD of DE = 25 and 19 had lower PVs than those prepared with MD of DE = 11. The difference in PV can be ascribed to the difference in the surface-oil ratio of the spray-dried microcapsules.

Detection of cracks in dried spaghetti using transmission images.

Cracks are formed during the drying process of spaghetti production, which reduces its commercial value and quality; hence, it is very important to detect the cracks during the manufacturing process of dried spaghetti. However, the presence of mottles, originating from wheat bran, hinders automatic identification of cracks. In this study, we developed a simple method to detect the cracks induced in spaghetti using a digital camera. The cracks and mottles were distinguished by pixelating the transmission light image of the spaghetti and analyzing the image based on the geometric characteristics in the histogram consisting of all the pixels. The method was able to detect the cracks induced in the spaghetti with a rough surface, which was prepared via a bronze die using vacuum extrusion molding, as well as those induced in the spaghetti with a smooth surface, which was prepared using a Teflon die.