High resolution and high throughput analytical methods for d-tagatose and process related impurities using capillary electrophoresis.

d-tagatose is a low calorie multifunctional rare ketohexose sugar with sweetness similar to that of sucrose and it has high potential benefits for food and pharmaceutical industries. It is found in traces in some fruits as a natural component. In view of its high demand as a substitute for sugar, mass production of d-tagatose through enzymatic conversion of Lactose to d-tagatose is adopted. The existing HPLC method has limitations with respect sensitivity and resolution in quantification and monitoring of d-tagatose in the presence of its process related impurities. In the present investigation a new robust, fast and green analytical technique has been developed based on capillary electrophoresis (CE) for the separation and quantification of d-tagatose in presence of other sugars: Lactose, d-glucose, d-galactose and d-talose. Optimum conditions are found to be: Back Ground Electrolyte (BGE): 36 mM of Na2HPO4 and 130 mM of NaOH; pH: 12.6; voltage: +18 kV for high resolution and -18 kV for high throughput methods with direct UV-Detector at 265 nm. At these optimum conditions, good separation between the sugars is achieved in less than 20 min for high resolution and less than 4 min for high throughput methods. The developed methodology is validated as per ICHQ2R1 guide lines and successfully applied for monitoring d-tagatose during the enzymatic conversion of Lactose/d-galactose to d-tagatose and also to determine the unknown amounts of d-tagatose in crystallized samples and further, it is used in identifying the d-tagatose in fruits.

Protective effects of curcumin on bleomycin-induced changes in lung glycoproteins.

The present study investigated the therapeutic effect of curcumin on bleomycin (BLM)-induced alterations in glycoprotein components in the fibrotic lungs. Analysis of the bronchoalveolar lavage fluid (BALF) demonstrated increased fibronectin content at 3, 5, 7, and 14 days after BLM administration. Similarly, lung tissue fibronectin content revealed a progressive increase at various times (days 3, 5, 7, 14, and 28) during the development of lung fibrosis. In addition, alveolar macrophage release of fibronectin was also elevated in BLM-treated rats. Analysis of carbohydrate moieties of glycoproteins revealed an increase in total hexose, fucose, sialic acid and hexosamine levels at 7, 14, and 28 days after BLM treatment. Furthermore, the activities of lung glycosidases such as N-acetyl-ß-D-glucosaminidase, ß-glucosidase, ß-galactosidase, and ß-fucosidase in the fibrotic rats were elevated. Importantly, curcumin significantly inhibited the BLM-induced increases in BALF and lung fibronectin levels. Treatment of BLM rats with curcumin dramatically suppressed alveolar macrophage release of fibronectin. Curcumin also inhibited the increases in complex carbohydrates and glycosidases in the fibrotic lungs. These findings suggest that BLM-induced lung fibrosis is associated with accumulation of glycoproteins, and curcumin has the ability to suppress the enhanced deposition of glycoproteins in the fibrotic lung.

Hydrophilic interaction anion exchange for separation of multiply modified neutral and anionic Dictyostelium N-glycans.

The unusual nature of the N-glycans of the cellular slime mould Dictyostelium discoideum has been revealed by a number of studies, primarily based on examination of radiolabeled glycopeptides but more recently also by MS. The complexity of the N-glycomes of even glycosylation mutants is compounded by the occurrence of anionic modifications, which also present an analytical challenge. In this study, we have employed hydrophilic interaction anion exchange (HIAX) HPLC in combination with MALDI-TOF MS/MS to explore the anionic N-glycome of the M31 (modA) strain, which lacks endoplasmic reticulum α-glucosidase II, an enzyme conserved in most eukaryotes including Homo sapiens. Prefractionation with HIAX chromatography enabled the identification of N-glycans with unusual oligo-α1,2-mannose extensions as well as others with up to four anionic modifications. Due to the use of hydrofluoric acid treatment, we were able to discriminate isobaric glycans differing in the presence of sulphate or phosphate on intersected structures as opposed to those carrying GlcNAc-phosphodiesters. The latter represent biosynthetic intermediates during the pathway leading to formation of the methylphosphorylated mannose epitope, which may have a similar function in intracellular targeting of hydrolases as the mannose-6-phosphate modification of lysosomal enzymes in mammals. In conclusion, HIAX in combination with MS is a highly sensitive approach for both fine separation and definition of neutral and anionic N-glycan structures.

High-yield production of pure tagatose from fructose by a three-step enzymatic cascade reaction.

OBJECTIVE: To produce tagatose from fructose with a high conversion rate and to establish a high-yield purification method of tagatose from the reaction mixture. RESULTS: Fructose at 1 M (180 g l-1) was converted to 0.8 M (144 g l-1) tagatose by a three-step enzymatic cascade reaction, involving hexokinase, plus ATP, fructose-1,6-biphosphate aldolase, phytase, over 16 h with a productivity of 9 g l-1 h-1. No byproducts were detected. Tagatose was recrystallized from ethanol to a purity of 99.9% and a yield of 96.3%. Overall, tagatose at 99.9% purity was obtained from fructose with a yield of 77%. CONCLUSION: This is the first biotechnological production of tagatose from fructose and the first application of solvent recrystallization for the purification of rare sugars.

Avoiding misannotation of in-source fragmentation products as cellular metabolites in liquid chromatography-mass spectrometry-based metabolomics.

Liquid chromatography-mass spectrometry (LC-MS) technology allows for rapid quantitation of cellular metabolites, with metabolites identified by mass spectrometry and chromatographic retention time. Recently, with the development of rapid scanning high-resolution high accuracy mass spectrometers and the desire for high throughput screening, minimal or no chromatographic separation has become increasingly popular. When analyzing complex cellular extracts, however, the lack of chromatographic separation could potentially result in misannotation of structurally related metabolites. Here, we show that, even using electrospray ionization, a soft ionization method, in-source fragmentation generates unwanted byproducts of identical mass to common metabolites. For example, nucleotide-triphosphates generate nucleotide-diphosphates, and hexose-phosphates generate triose-phosphates. We evaluated yeast intracellular metabolite extracts and found more than 20 cases of in-source fragments that mimic common metabolites. Accordingly, chromatographic separation is required for accurate quantitation of many common cellular metabolites.

Chiral separation of D/L-aldoses by micellar electrokinetic chromatography using a chiral derivatization reagent and a phenylboronic acid complex.

A novel method was developed for D/L-isomeric separation of aldopentoses and aldohexoses as their (S)-(+)-4-(N,N-dimethylaminosulfonyl)-7-(3-aminopyrrolidin-1-yl)-2,1,3-benzoxadiazole derivatives using phenylboronate buffer containing sodium dodecyl sulfate as a background electrolyte. The combination of derivatization with a chiral labeling reagent and micellar electrokinetic chromatography with phenylboronate made possible the efficient separation of D/L isomers as well as epimeric isomers of aldopentoses and aldohexoses. Laser-induced fluorescence detection permitted the micromolar-level determination of monosaccharide derivatives. The limit of detection was 105 amol (300 nM), and the repeatabilities of the migration times and peak area responses were 0.8 % and 7.9 % (relative standard deviation; n = 6), respectively. The method was applied to the determination of D/L- galactose in red seaweed.

Water scarcity conditions affect peach fruit size and polyphenol contents more severely than other fruit quality traits.

BACKGROUND: The literature abounds with the impacts of drought conditions on the concentration of non-structural compounds (NSC) in peach fruits without distinction as to the direct effect of drought on fruit metabolism and its indirect effect through dilution. Moreover, there is a need to investigate the sensitivity of the fruit composition to progressive water deficit in semi-arid conditions, as well as the origin of variations in fruit composition - not only in carbohydrates and organic acids, but also in secondary metabolites such as polyphenols. RESULTS: The increase in stress intensity resulted in smaller fruits and a reduction in yield. Drought increased fruit dry matter content, structural dry matter (SDM) content and firmness due to lower water import to fruits, although drought reduced fruit surface conductance and its transpiration. Drought significantly affected the concentrations of each NSC either through the decrease in dilution and/or modifications of their metabolism. The increase in hexoses and sorbitol concentrations of fruits grown under drought conditions resulted in an increase in the sweetness index but not near harvest. Malic acid concentration and content:SDM ratio increased as drought intensified, whereas those of citric and quinic acids decreased. Polyphenol concentration and content increased under severe drought. CONCLUSION: The increase in stress intensity strongly affected fruit mass. The concentration of total carbohydrates and organic acid at harvest increased mainly through a decrease in fruit dilution, whereas the concentrations of polyphenols were also strongly affected through an impact on their metabolism.

A new HPLC-based assay for the measurement of fructosamine-3-kinase (FN3K) and FN3K-related protein activity in human erythrocytes.

BACKGROUND: An impact on glycation, and possibly on diabetic complications, is attributed to fructosamine-3-kinase (FN3K) and its related protein (FN3K-RP) because they degrade Amadori compounds in vivo. Little is known about individual differences in FN3K-RP activity, which might contribute to an individual risk for diabetic complications. METHODS: An HPLC-based activity assay for FN3K-RP in erythrocytes with the substrate N-α-hippuryl-N-ε-psicosyllysine was developed. The activities of FN3K and FN3K-RP were also analysed in erythrocytes of 103 consecutive participants of a health-care survey amongst a high-risk group for diabetes. The potential associations of these activities with the subjects' health background (anthropometric data, glucose tolerance and HbA1c, blood lipids, history of metabolic diseases in the subjects and their families, and medication) were examined. RESULTS: The interindividual variability of FN3K-RP is less pronounced than that of FN3K [60-135 vs. 2.8-12.5 mU/g haemoglobin (Hb)]. No correlations with age, sex, body weight, blood cholesterol, or plasma glucose in an oral glucose tolerance test were observed. Subjects with kidney disease had higher activity of mainly FN3K-RP [111±15 vs. 98±18 mU/g Hb, mean±standard deviations (SDs), n=16 vs. 87, p=0.009], whereas subjects whose parents or siblings had a stroke showed lower FN3K activity (6.2±1.6 vs. 7.1±1.8 mU/g Hb, mean±SD, n=24 vs. 66, p=0.040). CONCLUSIONS: There is a likely impact of FN3K and FN3K-RP on the glycation cascade in vivo with potential positive and negative effects. The new screening method enables further studies to elucidate the function and importance of FN3K-RP.

Physiological responses of biomass allocation, root architecture, and invertase activity to copper stress in young seedlings from two populations of Kummerowia stipulacea (maxim.) Makino.

In the current study, we hypothesize that mine (metallicolous) populations of metallophytes form a trade-off between the roots and shoots when under copper (Cu) stress to adapt themselves to heavy metal contaminated habitats, and thus, differ from normal (non-metallicolous) populations in biomass allocation. To test the hypothesis, two populations of the metallophyte Kummerowia stipulacea, one from an ancient Cu mine (MP) and the other from a non-contaminated site (NMP), were treated with Cu(2+) in hydroponic conditions. The results showed that MP plants had higher root/shoot biomass allocation and more complicated root system architecture compared to those of the NMP plants when under Cu stress. The net photosynthetic capacity was more inhibited in the NMP plants than in the MP plants when under Cu stress. The sugar (sucrose and hexose) contents and acid invertase activities of MP plants were elevated while those in NMP plants were inhibited after Cu treatment. The neutral/alkaline invertase activities and sucrose synthase level showed no significant differences between the two populations when under Cu stress. The results showed that acid invertase played an important role in biomass allocation and that the physiological responses were beneficial for the high root/shoot biomass allocation, which were advantageous during adaptive evolution to Cu-enriched mine soils.

Evaluation of decontamination efficacy of cleaning solutions on stainless steel and glass surfaces contaminated by 10 antineoplastic agents.

OBJECTIVES: The handling of antineoplastic agents results in chronic surface contamination that must be minimized and eliminated. This study was designed to assess the potential of several chemical solutions to decontaminate two types of work surfaces that were intentionally contaminated with antineoplastic drugs. METHODS: A range of solutions with variable physicochemical properties such as their hydrophilic/hydrophobic balance, oxidizing power, desorption, and solubilization were tested: ultrapure water, isopropyl alcohol, acetone, sodium hypochlorite, and surfactants such as dishwashing liquid (DWL), sodium dodecyl sulfate (SDS), Tween 40, and Span 80. These solutions were tested on 10 antineoplastic drugs: cytarabine, gemcitabine, methotrexate, etoposide phosphate, irinotecan, cyclophosphamide, ifosfamide, doxorubicin, epirubicin, and vincristine. To simulate contaminated surfaces, these molecules (200ng) were deliberately spread onto two types of work surfaces: stainless steel and glass. Recovered by wiping with a specific aqueous solvent (acetonitrile/HCOOH; 20/0.1%) and an absorbent wipe (Whatman 903®), the residual contamination was quantified using high-performance liquid chromatography (HPLC) coupled to mass spectrometry. To compare all tested cleaning solutions, a performance value of effectiveness was determined from contamination residues of the 10 drugs. RESULTS: Sodium hypochlorite showed the highest overall effectiveness with 98% contamination removed. Ultrapure water, isopropyl alcohol/water, and acetone were less effective with effectiveness values of 76.8, 80.7, and 40.4%, respectively. Ultrapure water was effective on most hydrophilic molecules (97.1% for cytarabine), while on the other hand, isopropyl alcohol/water (70/30, vol/vol) was effective on the least hydrophilic ones (85.2% for doxorubicin and 87.8% for epirubicin). Acetone had little effect, whatever the type of molecule. Among products containing surfactants, DWL was found effective (91.5%), but its formulation was unknown. Formulations with single surfactant non-ionics (tween 40 and span 80) or anionic (SDS) were also tested. Finally, solutions containing 10(-2) M anionic surfactants and 20% isopropyl alcohol had the highest global effectiveness at around 90%. More precisely, their efficacy was the highest (94.8%) for the most hydrophilic compounds such as cytarabine and around 80.0% for anthracyclines. Finally, the addition of isopropyl alcohol to surfactant solutions enhanced their decontamination efficiency on the least hydrophilic molecules. Measured values from the stainless steel surface were similar to those from the glass one. CONCLUSION: This study demonstrates that all decontamination agents reduce antineoplastic contamination on work surfaces, but none removes it totally. Although very effective, sodium hypochlorite cannot be used routinely on stainless steel surfaces. Solutions containing anionic surfactant such as SDS, with a high efficiency/safety ratio, proved most promising in terms of surface decontamination.

Wine composition plays an important role in the control of carcinogenic precursor formation by Lactobacillus hilgardii X1B.

BACKGROUND: Lactobacillus hilgardii, a wine lactic acid bacterium, is able to use arginine, through the arginine deiminase pathway with the formation of citrulline, a precursor of the carcinogen ethyl carbamate. The influence of different Argentine wine varieties (Merlot, Cabernet Sauvignon and Malbec), on bacterial growth and arginine metabolism was examined. Furthermore, the effect of different components normally present in wines on the enzyme activities of the arginine deiminase system was determined. RESULTS: Malbec wine under all conditions assayed (33, 50 and 100% supplemented wine:basal media) showed higher arginine consumption and citrulline production than the other wines, as well as the highest bacterial growth and survival of Lactobacillus hilgardii X1B. Glucose and L-malic inhibited both arginine deiminase enzymes while fructose and citric acid only inhibited arginine deiminase. The red wines assayed in this study had different composition, and this is an explanation for the different behavior of the bacterium. CONCLUSION: The highest citrulline production in Malbec wine could be correlated with its lower concentrations of glucose, fructose, citric and phenolic acid than the other wines. Therefore, a wine with lower concentration of these sugars and acids could be dangerous due to the formation of ethyl carbamate precursors.

Stable carbon isotope ratio analysis of anhydrosugars in biomass burning aerosol particles from source samples.

A new method for stable carbon isotope ratio analysis of anhydrosugars from biomass burning aerosol particle source filter samples was developed by employing Thermal Desorption--2 Dimensional Gas Chromatography--Isotope Ratio Mass Spectrometry (TD-2DGC-IRMS). Compound specific isotopic measurements of levoglucosan, mannosan, and galactosan performed by TD-2DGC-IRMS in a standard mixture show good agreement with isotopic measurements of the bulk anhydrosugars, carried out by Elemental Analyzer--Isotope Ratio Mass Spectrometry (EA-IRMS). The established method was applied to determine the isotope ratios of levoglucosan, mannosan, and galactosan from source samples collected during combustion of hard wood, softwood, and crop residues. δ(13)C values of levoglucosan were found to vary between -25.6 and -22.2‰, being higher in the case of softwood. Mannosan and galactosan were detected only in the softwood samples showing isotope ratios of -23.5‰ (mannosan) and -25.7‰ (galactosan). The isotopic composition of holocellulose in the plant material used for combustion experiments was determined with δ(13)C values between -28.5 and -23.7‰. The difference in δ(13)C of levoglucosan in biomass burning aerosol particles compared to the parent fuel holocellulose was found to be -1.89 (±0.37)‰ for the investigated biomass fuels. Compound specific δ(13)C measurements of anhydrosugars should contribute to an improved source apportionment.

Anti-complementary activity of enzyme-treated traditional Korean rice wine (Makgeolli) hydrolysates.

BACKGROUND: Makgeolli brewed from rice contains about 150 g kg(-1) alcohol and has a fragrance as well as an acidic and sweet taste. During the brewing process, by-products such as rice bran and brewery cake are produced. At the end of fermentation the matured mash is transferred to a filter cloth and the Makgeolli is squeezed out from the cake, leaving the lees of the mash. These by-products have continued to increase every year, resulting in an ecological problem. It is therefore important to develop new uses for them. The objective of this study was to use the by-products from the brewing of Makgeolli as a valuable functional food or nutraceutical. RESULTS: The anti-complementary activities of crude polysaccharides isolated from Cytolase hydrolysates of Makgeolli lees at concentrations of 1000 and 500 µg mL(-1) were 84.15 and 78.70% respectively. The activity of polysaccharide krestin (PSK) was 60.00% at 1000 µg mL(-1). The active polysaccharide obtained with Cytolase comprised mainly glucose and mannose (molar ratio 1.00:0.62). CONCLUSION: Glucose- and mannose-rich crude polysaccharides were isolated from the Cytolase hydrolysate of Makgeolli lees. The polysaccharides retain anti-complementary activity to enhance the immune system as a functional food or nutraceutical.

Composition of hydroponic lettuce: effect of time of day, plant size, and season.

BACKGROUND: The diurnal variation of nitrate and sugars in leafy green vegetables may vary with plant size or the ability of plants to buffer the uptake, synthesis, and use of metabolites. Bibb lettuce was grown in hydroponics in a greenhouse and sampled at 3 h intervals throughout one day in August 2007 and another day in November 2008 to determine fresh weight, dry matter, and concentration of nitrate and sugars. Plantings differing in size and age were sampled on each date. RESULTS: The dry/fresh weight ratio increased during the daylight period. This increase was greater for small compared to large plants. On a fresh weight basis, tissue nitrate of small plants was only half that of larger plants. The variation in concentration with time was much less for nitrate than for soluble sugars. Soluble sugars were similar for all plant sizes early in the day, but they increased far more for small compared to large plants in the long days of summer. CONCLUSION: The greatest yield on a fresh weight basis was obtained by harvesting lettuce at dawn. Although dry matter or sugar content increased later in the day, there is no commercial benefit to delaying harvest as consumers do not buy lettuce for these attributes.

Changes in carbohydrate metabolism in Plasmopara viticola-infected grapevine leaves.

The oomycete Plasmopara viticola is responsible for downy mildew, a severe grapevine disease. In infected grapevine leaves, we have observed an abnormal starch accumulation at the end of the dark period, suggesting modifications in starch metabolism. Therefore, several complementary approaches, including transcriptomic analyses, measurements of enzyme activities, and sugar quantification, were performed in order to investigate and to understand the effects of P. viticola infection on leaf starch and-to a larger extent-carbohydrate metabolism. Our results indicate that starch accumulation is associated with an increase in ADP-glucose pyrophosphorylase (AGPase) activity and modifications in the starch degradation pathway, especially an increased α-amylase activity. Together with these alterations in starch metabolism, we have observed an accumulation of hexoses, an increase in invertase activity, and a reduction of photosynthesis, indicating a source-to-sink transition in infected leaf tissue. Additionally, we have measured an accumulation of the disaccharide trehalose correlated to an increased trehalase gene expression and enzyme activity. Altogether, these results highlight a dramatic alteration of carbohydrate metabolism correlated with later stages of P. viticola development in leaves.

Core and intact polar glycerol dibiphytanyl glycerol tetraether lipids of ammonia-oxidizing archaea enriched from marine and estuarine sediments.

Glycerol dibiphytanyl glycerol tetraether (GDGT)-based intact membrane lipids are increasingly being used as complements to conventional molecular methods in ecological studies of ammonia-oxidizing archaea (AOA) in the marine environment. However, the few studies that have been done on the detailed lipid structures synthesized by AOA in (enrichment) culture are based on species enriched from nonmarine environments, i.e., a hot spring, an aquarium filter, and a sponge. Here we have analyzed core and intact polar lipid (IPL)-GDGTs synthesized by three newly available AOA enriched directly from marine sediments taken from the San Francisco Bay estuary ("Candidatus Nitrosoarchaeum limnia"), and coastal marine sediments from Svalbard, Norway, and South Korea. Like previously screened AOA, the sedimentary AOA all synthesize crenarchaeol (a GDGT containing a cyclohexane moiety and four cyclopentane moieties) as a major core GDGT, thereby supporting the hypothesis that crenarchaeol is a biomarker lipid for AOA. The IPL headgroups synthesized by sedimentary AOA comprised mainly monohexose, dihexose, phosphohexose, and hexose-phosphohexose moieties. The hexose-phosphohexose headgroup bound to crenarchaeol was common to all enrichments and, in fact, the only IPL common to every AOA enrichment analyzed to date. This apparent specificity, in combination with its inferred lability, suggests that it may be the most suitable biomarker lipid to trace living AOA. GDGTs bound to headgroups with a mass of 180 Da of unknown structure appear to be specific to the marine group I.1a AOA: they were synthesized by all three sedimentary AOA and "Candidatus Nitrosopumilus maritimus"; however, they were absent in the group I.1b AOA "Candidatus Nitrososphaera gargensis."

Increase in the activity of fructose-1,6-bisphosphatase in cytosol affects sugar partitioning and increases the lateral shoots in tobacco plants at elevated CO2 levels.

We generated transgenic tobacco plants with high levels of fructose-1,6-bisphosphatase expressing cyanobacterialfructose-1,6-/sedoheptulose-1,7-bisphosphatase in the cytosol. At ambient CO(2) levels (360 ppm), growth, photosynthetic activity, and fresh weight were unchanged but the sucrose/hexose/starch ratio was slightly altered in the transgenic plants compared with wild-type plants. At elevated CO(2) levels (1200 ppm), lateral shoot, leaf number, and fresh weight were significantly increased in the transgenic plants. Photosynthetic activity was also increased. Hexose accumulated in the upper leaves in the wild-type plants, while sucrose and starch accumulated in the lower leaves and lateral shoots in the transgenic plants. These findings suggest that cytosolic fructose-1,6-bisphosphatase contributes to the efficient conversion of hexose into sucrose, and that the change in carbon partitioning affects photosynthetic capacity and morphogenesis at elevated CO(2) levels.

Modulation of organic acids and sugar content in tomato fruits by an abscisic acid-regulated transcription factor.

Growing evidence suggests that the phytohormone abscisic acid (ABA) plays a role in fruit development. ABA signaling components of developmental programs and responses to stress conditions include the group of basic leucine zipper transcriptional activators known as ABA-response element binding factors (AREBs/ABFs). AREB transcription factors mediate ABA-regulated gene expression involved in desiccation tolerance and are expressed mainly in seeds and in vegetative tissues under stress; however, they are also expressed in some fruits such as tomato. In order to get an insight into the role of ABA signaling in fruit development, the expression of two AREB-like factors were investigated during different developmental stages. In addition, tomato transgenic lines that overexpress and downregulate one AREB-like transcription factor, SlAREB1, were used to determine its effect on the levels of some metabolites determining fruit quality. Higher levels of citric acid, malic acid, glutamic acid, glucose and fructose were observed in SlAREB1-overexpressing lines compared with those in antisense suppression lines in red mature fruit pericarp. The higher hexose concentration correlated with increased expression of genes encoding a vacuolar invertase (EC 3.2.1.26) and a sucrose synthase (EC 2.4.1.13). No significant changes were found in ethylene content which agrees with the normal ripening phenotype observed in transgenic fruits. These results suggest that an AREB-mediated ABA signal affects the metabolism of these compounds during the fruit developmental program.

Reagentless D-Tagatose Biosensors Based on the Oriented Immobilization of Fructose Dehydrogenase onto Coated Gold Nanoparticles- or Reduced Graphene Oxide-Modified Surfaces: Application in a Prototype Bioreactor.

As electrode nanomaterials, thermally reduced graphene oxide (TRGO) and modified gold nanoparticles (AuNPs) were used to design bioelectrocatalytic systems for reliable D-tagatose monitoring in a long-acting bioreactor where the valuable sweetener D-tagatose was enzymatically produced from a dairy by-product D-galactose. For this goal D-fructose dehydrogenase (FDH) from Gluconobacter industrius immobilized on these electrode nanomaterials by forming three amperometric biosensors: AuNPs coated with 4-mercaptobenzoic acid (AuNP/4-MBA/FDH) or AuNPs coated with 4-aminothiophenol (AuNP/PATP/FDH) monolayer, and a layer of TRGO on graphite (TRGO/FDH) were created. The immobilized FDH due to changes in conformation and spatial orientation onto proposed electrode surfaces catalyzes a direct D-tagatose oxidation reaction. The highest sensitivity for D-tagatose of 0.03 ± 0.002 µA mM-1cm-2 was achieved using TRGO/FDH. The TRGO/FDH was applied in a prototype bioreactor for the quantitative evaluation of bioconversion of D-galactose into D-tagatose by L-arabinose isomerase. The correlation coefficient between two independent analyses of the bioconversion mixture: spectrophotometric and by the biosensor was 0.9974. The investigation of selectivity showed that the biosensor was not active towards D-galactose as a substrate. Operational stability of the biosensor indicated that detection of D-tagatose could be performed during six hours without loss of sensitivity.

Effect of sorbitan monopalmitate on the polymorphic transitions and physicochemical properties of mango butter.

The present study reports the effect of sorbitan monopalmitate (SM) as a crystallization modifier on the physicochemical properties of mango butter (MB). The concentration of SM was varied in the range of 1 and 5 wt%. The addition of SM promoted the aggregation of globular MB crystals. The FTIR patterns did not show any significant changes when SM was added. XRD and DSC analyses confirmed the crystallization of MB crystals in stable ß' and ß (V) polymorphic states. However, SM also introduced imperfections in the crystal lattices of MB. Among all formulations, M2 (SM; 1% w/w) possessed a mechanically stable network structure. The crystallization rate of MB was tailored by SM in a concentration-dependent manner. The solid content was highest in M4 (SM; 5% w/w) at 10 °C and 30 °C among all the oleogels. In gist, SM in manageable quantities can be utilized for preparing custom-tailored MB-based products.