Addition Of Lactose Research Articles

Effect of drying methods on the reactivity of chitosan towards Maillard reaction

The effect of drying methods on chitosan reactivity towards Maillard reaction during storage of dried chitosan–lactose systems was investigated. Two different structural forms of chitosan, scaffold and microspheres, were prepared. Then they were dried by lyophilization or using supercritical fluid technology (SF-CO2) and stored with lactose under controlled temperature conditions (60 °C) and water activity (aw = 0.65). The drying method produced slight modifications on the chitosan structure especially in samples submitted to SF-CO2 treatment. Differences were more evident in the reactivity of chitosan–lactose systems during storage. Maillard reaction development was assessed by quantification of a new compound which originated from the acid hydrolysis of Amadori compounds (NFMD) resulting from chitosan–lactose interactions, and not detected in the acid hydrolysates of freshly prepared chitosan-lactose systems. Maillard reaction was influenced by different factors such as the manner of lactose addition, structure of chitosan (microspheres and scaffolds) and drying method. Lyophilized chitosan in the form of microspheres with lactose, presented the highest values of NFMD (428.45 mg/100 g of sample). The determination of this compound could be used as an index of the progress of Maillard reaction.

Revealing Fibroblast Growth Factor Receptor-1 and Klotho-Beta Plasma Membrane Dynamics with FRAP and Number and Brightness Analysis

Fibroblast growth factor-21 (FGF21) is a newly appreciated endocrine ligand that signals through fibroblast growth factor receptor-1 (FGFR1). Long term FGF21 treatment has been shown to decrease blood glucose levels in diabetic mouse models. Consequently, the signalling pathway of FGF21/FGFR1 has become a target for the management of diabetes. FGF21 activity requires the expression of a unique co-receptor Klotho-beta (KLB). This dependence suggests FGF21 signals through a FGFR1/KLB complex. To investigate the molecular interactions between FGFR1 and KLB at the plasma membrane, we have created fluorescently-labelled constructs of these receptors. Through FRAP, we revealed that KLB has a significantly shorter recovery half-life than FGFR1. After the addition of lactose, a competitive inhibitor of galectin lattice binding, the recovery half-life of KLB increased with no effect on FGFR1. After addition of FGF21, cells co-expressing KLB and FGFR1 also showed increased recovery half-life. This suggests that KLB interacts with the galectin lattice and co-expression of FGFR1 removes this interaction. To study complex formation of FGFR1 and KLB with the addition of FGF21, we employed the recently developed technique of Number and Brightness Analysis. It was found that KLB oligomerizes greater than 2-fold with the addition of FGF21; however, treatment with lactose abolished this response. In contrast, FGFR1-expressing cells showed no change in oligomerization state. In cells co-expressing KLB and FGFR1, FGF21 induced no significant change in KLB aggregation state while inducing a nearly 2-fold increase in FGFR1. Overall, these data suggest KLB associates with the galectin lattice in the absence of FGFR1, and that FGFR1 and KLB form a 1:2 complex that transitions to 2:2 upon addition of FGF21. Future studies will address how these interactions affect the downstream signalling of this important endocrine factor.

Detection of Hazelnut in Foods Using ELISA: Challenges Related to the Detectability in Processed Foodstuffs

Hazelnuts are widely used nowadays, and can pose a serious threat to allergic consumers due to cross-contamination that may occur during processing. This might lead to the presence of hidden hazelnut in foods. Therefore, reliable tests are needed to detect hazelnut, especially in processed foods. A hazelnut-specific indirect competitive ELISA based on polyclonal chicken antibodies was developed. The polyclonal antibodies were raised against modified hazelnut proteins in order to improve the detectability of hazelnut proteins in processed foods. The assay showed a detection limit of 1.36 microg hazelnut protein/mL of 5 mM urea in phosphate-buffered saline buffer (pH 7.4). Limited cross-reactivity with walnut and pecan nut was observed; no cross-reactivity was observed with other food ingredients. Blank cookies spiked before analysis showed recoveries of 73-107%. However, cookies spiked before baking showed that the detectability was severely decreased. Addition of lactose to the cookies, which led to more severe modification through the Maillard reaction, led to an increase in the detectability. These results indicate that using antibodies developed toward allergens modified through food processing-simulating reactions is a better approach for detection.

L-glutamine and L-glutamate in diets with different lactose levels for piglets weaned at 21 days of age

This study was developed to evaluate the effects of adding L-glutamine and L-glutamate in diets with no lactose or with 4.0 or 8.0% lactose inclusion for piglets weaned at 21 days old. One hundred and eight piglets with initial weight of 6.12±0.70 kg were allotted in a complete randomized block design, in a 3 × 2 factorial arrangement, with six treatments, six replicates, and three piglets per experimental unit. The experimental diets were supplied from 21 to 35 days. From 36 to 49 days, animals received the same diet with no lactose inclusion, but the animals in the treatments with L-glutamine + L-glutamate in the previous phase continued to receive diets containing these ingredients. There was no interaction between the level of lactose and the inclusion of L-glutamine + L-glutamate on the parameters evaluated. The levels of lactose did not affect the performance of piglets in either of the two periods. Adding L-glutamine and L-glutamate in the diet positively influenced the weight gain of pigs from 21 to 49 days of age and increased the villous height in the duodenum, jejunum and ileum. Inclusion of L-glutamine + L-glutamate in diets for piglets weaned at 21 days of age improves the performance and the intestinal mucosa morphology, regardless of lactose addition.

Influence of lactose and lactate on growth and β-galactosidase activity of potential probiotic Propionibacterium acidipropionici

Dairy propionibacteria are microorganisms of interest for their role as starters in cheese technology and as well as their functions as probiotics. Previous studies have demonstrated that Propionibacterium acidipropionici metabolize lactose by a β-galactosidase that resists the gastrointestinal transit and the manufacture of a Swiss-type cheese, so that could be considered for their inclusion in a probiotic product assigned to intolerant individuals. In the present work we studied the effect of the sequential addition of lactose and lactate as first or second energy sources on the growth and β-galactosidase activity of P. acidipropionici Q4. The highest β-galactosidase activity was observed in a medium containing only lactate whereas higher final biomass was obtained in a medium with lactose. When lactate was used by this strain as a second energy source, a marked increase of the intracellular pyruvate level was observed, followed by lactate consumption and increase of specific β-galactosidase activity whereas lactose consumption became negligible. On the contrary, when lactose was provided as second energy source, lactic acid stopped to be metabolized, a decrease of the intracellular pyruvate concentration was observed and β-galactosidase activity sharply returned to a value that resembled the observed during the growth on lactose alone. Results suggest that the relative concentration of each substrate in the culture medium and the intracellular pyruvate level were decisive for both the choice of the energetic substrate and the β-galactosidase activity in propionibacteria. This information should be useful to decide the most appropriate vehicle to deliver propionibacteria to the host in order to obtain the highest β-galactosidase activity.

THE EFFECT OF DIFFERENT HEAT STERILIZATION REGIMES ON THE QUALITY OF CANNED PROCESSED CHEESE

ABSTRACTThe impact of four different regimes of heat sterilization (110C for 100 min, 115C for 32 min, 120C for 10 min and 125C for 3.2 min) on the properties of processed cheeses was evaluated. Also, nonsterilized samples were analyzed. Samples without and with the addition of lactose (0.5–2.0% w/w) were studied because lactose might be present in raw materials at various concentrations and might significantly affect processed cheese quality. All the sterilization regimes ensured inactivation of microflora. When the sterilization temperature was reduced (with simultaneously prolonged exposure time) the samples showed worse sensory properties. Significant hydrolytic changes of proteins and larger amino acid losses were also detected. The smallest changes were noted in products treated at 125C for 3.2 min. The heat treatment at 120C for 10 min caused acceptable modification of cheese properties. Addition of lactose higher than 1.0% w/w was found unsuitable for the production of sterilized processed cheeses.PRACTICAL APPLICATIONSProcessed cheese is a natural cheese‐based foodstuff manufactured using heat treatment (especially at 80–100C). Sterilized processed cheese is a specific product with prolonged shelf life, which could be used either in everyday life or for military and rescue team boarding during operations (Buňka et al. 2004). This product is manufactured in many countries but only limited scientific information about its quality and properties is available. Powdered skim milk and whey (used mainly for cutting the costs of the ingredients), which contain high amounts of lactose, are widely used in production of processed cheese. Lactose can show a deteriorating effect on the quality of processed cheeses, especially after application of severe heat treatment. Results of this study could be useful for setting sterilization time and temperature in order to manufacture products with high nutritive and sensory value. Moreover, a comparative study exploring acceptable lactose concentration value was carried out.

Distinct Roles of β-Galactosidase Paralogues of the Rumen Bacterium Mannheimia succiniciproducens

Mannheimia succiniciproducens, a rumen bacterium belonging to the family Pasteurellaceae, has two putative β-galactosidase genes, bgaA and bgaB, encoding polypeptides whose deduced amino acid sequences share 56% identity with each other and show approximately 30% identity to the Escherichia coli gene for LacZ. The M. succiniciproducens bgaA (MsbgaA) gene-deletion mutant was not able to grow on lactose as the sole carbon source, suggesting its essential role in lactose metabolism, whereas the MsbgaB gene-deletion mutant did not show any growth defect on a lactose medium. Furthermore, the expression of the MsbgaA gene was induced by the addition of lactose in the growth medium, whereas the MsbgaB gene was constitutively expressed independently of a carbon source. Biochemical characterization of the recombinant proteins revealed that MsBgaA is more efficient than MsBgaB in hydrolyzing o-nitrophenyl-β-d-galactopyranoside and p-nitrophenyl-β-d-galactopyranoside. MsBgaA was highly specific for the hydrolysis of lactose, with a catalytic efficiency of 46.9 s(-1) mM(-1). However, MsBgaB was more efficient for the hydrolysis of lactulose than lactose, and the catalytic efficiency was 10.0 s(-1) mM(-1). Taken together, our results suggest that the β-galactosidase paralogues of M. succiniciproducens BgaA and BgaB play a critical role in lactose metabolism and in an unknown but likely specific function for rumen bacteria, respectively.

Degradation of 2,4-dichlorophenoxyacetic acid by a halotolerant strain of Penicillium chrysogenum: antibiotic production

The extensive use of pesticides in agriculture has prompted intensive research on chemical and biological methods in order to protect contamination of water and soil resources. In this paper the degradation of the pesticide 2,4-dichlorophenoxyacetic acid by a Penicillium chrysogenum strain previously isolated from a salt mine was studied in batch cultures. Co-degradation of 2,4-dichlorophenoxyacetic acid with additives such as sugar and intermediates of pesticide metabolism was also investigated. Penicillium chrysogenum in solid medium was able to grow at concentrations up to 1000 mg/L of 2,4-dichlorophenoxyacetic acid (2,4-D) with sucrose. Meanwhile, supplementation of the solid medium with glucose and lactose led to fungal growth at concentrations up to 500 mg/L of herbicide. Batch cultures of 2,4-D at 100 mg/L were developed under aerobic conditions with the addition of glucose, lactose and sucrose, showing sucrose as the best additional carbon source. The 2,4-D removal was quantified by liquid chromatography. The fungus was able to use 2,4-D as the sole carbon and energy source under 0%, 2% and 5.9% NaCl. The greatest 2,4-D degradation efficiency was found using α -ketoglutarate and ascorbic acid as co-substrates under 2% NaCl at pH 7. Penicillin production was evaluated in submerged cultures by bioassay, and higher amounts of β -lactam antibiotic were produced when the herbicide was alone. Taking into account the ability of P. chrysogenum CLONA2 to degrade aromatic compounds, this strain could be an interesting tool for 2,4-D herbicide remediation in saline environments.

Improving Functionality of Whole Egg Powder by the Addition of Gelatine, Lactose, and Pullulan

The addition of gelatine (G), lactose (L), pullulan (P), and their mixtures at equal ratios (gelatine + lactose [GL] and gelatin + pullulan [GP]) to whole egg prior to drying was studied. Their effects on the functional properties (emulsion and gelling ability, water holding capacity of gel, foaming, color) and soluble protein content of spray dried egg powder during the 6 mo of storage at 20 °C and 50% relative humidity were investigated. It was demonstrated that the emulsion and foaming stability, water holding capacity of gel, and color change were significantly affected by the storage time, whereas storage time did not affect the strength of gel texture prepared by egg powders. Gelatine and pullulan improved the foaming stability and water holding capacity. Lactose caused a decrease in emulsion and foaming stability values. The maximum color change was observed for the plain egg powder, showing that mixing whole egg with carbohydrate- and/or protein-based additives before the drying process preserved the color of egg powder. Adding carbohydrate and/or protein caused significant changes in functional properties of egg powder.

Predictive tool for recombinant protein production in Escherichia coli Shake‐Flask cultures using an on‐line monitoring system

As Escherichia coli (E. coli) is well defined with respect to its genome and metabolism, it is a favored host organism for recombinant protein production. However, many processes for recombinant protein production run under suboptimal conditions caused by wrong or incomplete information from an improper screening procedure, because appropriate on-line monitoring systems are still lacking. In this study, the oxygen transfer rate (OTR), determined on-line in shake flasks by applying a respiration activity monitoring system (RAMOS) device, was used to characterize the metabolic state of the recombinant organisms. Sixteen clones of E. coli SCS1 with foreign gene sequences, encoding for different target proteins, were cultivated in an autoinduction medium, containing glucose, lactose, and glycerol, to identify relationships between respiration activity and target protein production. All 16 clones showed a remarkably different respiration activity, biomass, and protein formation under induced conditions. However, the clones could be classified into three distinct types, and correlations could be made between OTR patterns and target protein production. For two of the three types, a decrease of the target protein was observed, after the optimal harvest time had passed. The acquired knowledge was used to modify the autoinduction medium to increase the product yield. Additional 1.5 g/L glucose accelerated the production process for one clone, shifting the time point of the maximal product yield from 24 to 17 h. For another clone, lactose addition led to higher volumetric product yields, in fact 25 and 38% more recombinant protein for 2 and 6 g/L additional lactose, respectively.

Lactose levels in diets for piglets weaned at 21 days of age

With the objective of evaluating levels of lactose in diets for piglets weaned at 21 days of age, it was carried out an experiment with 72 animals, with average weight of 6.12 kg, distributed in a completely randomized block design with four diets (0, 4, 8, and 12% lactose), six replicates, and 3 animals per experimental unit. Animals were fed the experimental diets from 21 to 35 days of age and they were fed a lactose-free basal diet from 36 to 49 days of age. The lactose levels did not affect daily weight gain, feed intake and feed conversion of piglets from 21 to 35 days of age. The use of lactose levels in the diets also did not affect performance of the piglets assessed from 21 to 49 days old. Diets also did not influence villous height, crypt depth and villous:crypt ratio. Lactose resulted in greater diversity and balance of the intestinal microbial community. The Lactobalillus spp. richness increases with the addition of lactose in diet up to the level of 8% in relation to the total number of intestinal microorganisms, which may a possible improvement of intestinal health.

Formulation and Cost-Effective Drying of Probiotic Yeast

Saccharomyces boulardii yeast is considered as a probiotic according to the World Health Organization (WHO). Like any other probiotic, Saccharomyces boulardii is available as a freeze-dried formulation. Although freeze drying is the most preferred method of preserving the microorganisms, the process is very expensive. The cost of capsules containing freeze-dried probiotic yeast is certainly out of reach of the underprivileged population of the world. Hence, the present work focuses on developing a new formulation and cost-effective drying process for probiotic yeast. Freeze drying was compared with fluidized bed drying (FBD) and heat pump–assisted fluidized bed drying (HP-FBD) techniques for drying of Saccharomyces boulardii formulation. The process involves addition of lactose and microcrystalline cellulose to the biomass obtained by centrifugation and then making the dough. This blend is then extruded and spheronized to form granules. Heat pump fluidized bed drying of the formulation resulted in higher activity retention compared to atmospheric fluid bed drying. This encouraged further experimentation using HP-FBD to study the effect of various operating variables such as air temperature, air humidity, and velocity on the drying kinetics and the deactivation kinetics. It was observed that the temperature and humidity play a major role in the deactivation and drying, whereas the change in air velocity has comparatively less effect on both parameters. The effective diffusivity and the deactivation rate constants were correlated to the temperature using an Arrhenius-type equation.

The effect of addition of lactose on the oral absorption of a highly lipid soluble drug

The effect of addition of lactose on the oral absorption of a highly lipid soluble drug

The influence of drug and diluent particle size on the in vitro release of drug from hard gelatin capsules.

The in vitro release of a drug from capsules containing different proportions of controlled particle size fractions of acetylsalicylic acid and lactose, has been assessed in terms of the time for 50% of the drug content of the capsule to be released into solution during a dissolution test (T50), and by a standard disintegration test. In general the two types of test gave closely related responses although some discrepancies existed with certain systems. For capsules containing only the drug, the value of T50 increased as the particle size of the drug decreased. The addition of lactose generally reduced the T50 value, the extent of the reduction showing greater dependence on the proportion of lactose added than its particle size. Capsule formulations containing 80% w/w of lactose had values of T50 which were independent of drug or diluent particle size. Capsule formulations containing lower proportions of lactose usually had an optimum combination of particle size fractions of drug and diluent for maximum drug release. The relationship between drug release and the porosity within the capsule was dependent on the particle size of the drug.

The influence of functional properties of different whey protein concentrates on the rheological and emulsification capacity of blends with xanthan gum

The object of the study was the investigation of commercial WPCs with different protein contents (65 or 80%) and origins. The properties investigated were their solubility, oil-holding capacity, protein profiles, rheological properties and emulsification capacity in the presence of xanthan. The native protein profile of WPCs varied according to the source of the whey. Xanthan or lactose addition improved the stability of the pseudo-emulsions prepared. Adding lactose resulted in a greater amount of absorbed protein on the fat globule surface. Stabilization capacity also depended on the protein source; less pronounced effects were noticed by using proteins of different initial concentrations. The initial protein content influenced mainly the gelation process. A 15% increase in the protein amount (65 or 80%) resulted in threefold greater G′ values at 85°C. Composition and, more specifically, lactose or calcium divalent ions in the original protein samples influenced gelation temperature and further aggregation formation.

Biotinylation, a Post-translational Modification Controlled by the Rate of Protein-Protein Association

Biotin protein ligases catalyze specific covalent linkage of the coenzyme biotin to biotin-dependent carboxylases. The reaction proceeds in two steps, including synthesis of an adenylated intermediate followed by biotin transfer to the carboxylase substrate. In this work specificity in the transfer reaction was investigated using single turnover stopped-flow and quench-flow assays. Cognate and noncognate reactions were measured using the enzymes and minimal biotin acceptor substrates from Escherichia coli, Pyrococcus horikoshii, and Homo sapiens. The kinetic analysis demonstrates that for all enzyme-substrate pairs the bimolecular rate of association of enzyme with substrate limits post-translational biotinylation. In addition, in noncognate reactions the three enzymes displayed a range of selectivities. These results highlight the importance of protein-protein binding kinetics for specific biotin addition to carboxylases and provide one mechanism for determining biotin distribution in metabolism.

Lung Cancer-Derived Galectin-1 Mediates Dendritic Cell Anergy through Inhibitor of DNA Binding 3/IL-10 Signaling Pathway

Lung cancer, one of the leading causes of death worldwide, is often associated with a state of immune suppression, but the molecular and functional basis remains enigmatic. Evidence is provided in this paper supporting the role of lung cancer-derived soluble lectin, galectin-1, as a culprit in dendritic cell (DC) anergy. We have shown that galectin-1 is highly expressed in lung cancer cell lines, together with the serum and surgical samples from lung cancer patients. Functionally, lung cancer-derived galectin-1 has been shown to alter the phenotypes of monocyte-derived DCs (MdDCs) and impair alloreactive T cell response, concomitant with the increase of CD4(+)CD25(+)FOXP3(+) regulatory T cells. The regulatory effect of galectin-1 is mediated, in part, through its ability to induce, in an Id3 (inhibitor of DNA binding 3)-dependent manner, the expression of IL-10 in monocytes and MdDCs. This effect is inhibited by the addition of lactose, which normalizes the phenotypic and functional alterations seen in MdDCs. Of note, significant upregulation of IL-10 was seen in tumor-infiltrating CD11c(+) DCs in human lung cancer samples. This was also noted in mice transplanted with lung cancer cells, but not in those receiving tumor cells with galectin-1 knockdown. Furthermore, a significant reduction was noted in lung cancer incidence and in the levels of IL-10-expressing, tumor-infiltrating DCs, in mice receiving galectin-1-silenced tumor cells. These results thus suggest that the galectin-1/IL-10 functional axis may be crucial in lung cancer-mediated immune suppression, and that galectin-1 may serve as a target in the development of lung cancer immunotherapy.

Efficient synthesis of octyl-β-d-galactopyranoside by Bacillus spore-displayed β-galactosidase using an amphiphilic 1,2-dimethoxyethane co-solvent

For enzymatic synthesis of octyl-β-d-galactopyranoside (octyl-gal) from lactose and n-octanol, Escherichia coli β-galactosidase (β-Gal) was expressed and displayed on the surfaces of Bacillus subtilis spores. The spore-displayed β-Gal was found to be stable when an amphiphilic 1,2-dimethoxyethane (DME) was used as a co-solvent; the transgalactosylation efficiency and octyl-gal conversion were optimal at 50% (v/v) DME. In addition, the product was maximally obtained from 100mM lactose in a phosphate buffer/n-octanol/DME (25/25/50, v/v) mixture. By increasing the agitation speed and the amount of spores displaying β-Gal, a yield of 33.7mM octyl-gal was obtained over 24h in a batch mode, which is much higher than in other octyl-gal bioconversion processes, such as those involving lipid-coating, reverse micelles, or whole cells. On the other hand, intermittent addition of spore-displayed β-Gal and/or lactose in the reaction medium had no effect on the octyl-gal yield. The synthesized octyl-gal was hydrolyzed by the spore-displayed β-Gal, and a high concentration of octyl-gal competitively inhibited the enzymes (Ki value of 10.8mM). In summary, we demonstrate that octyl-gal synthesis by spore-displayed β-Gal in non-aqueous medium can be significantly improved with the use of DME as a co-solvent.

Uniform Chitosan Microparticles Prepared by a Novel Spray‐Drying Technique

Particle size and morphology are important properties of pharmaceutical particles. Preparation of microparticles with uniform particle size and morphology is necessary in order to systematically relate these properties to the release behavior and other functionalities such as drug encapsulation and dissolution. In this study, we successfully prepared monodisperse, nonagglomerated chitosan microparticles in a single step by a novel spray‐drying technique. The control of particle size and morphology of spray‐dried microparticles was investigated experimentally. Microparticles with larger particle size can be produced when chitosan precursor of higher concentration was used. Storage time of chitosan precursor, drying temperature, and addition of lactose were shown to be crucial parameters that affect the particle morphology. Appropriate choice of the drying temperature and precursor storage time permitted control of the particle morphology, ranging from nearly spherical to cap‐shaped. Surface characteristics of the particles can be finely tuned by the amount of lactose added into the chitosan precursor.

Effect of annealing time and addition of lactose on release of a model substance from Eudragit ® RS coated pellets produced by a fluidized bed coater

The aim of this study was to investigate the effects of annealing time and addition of lactose in coating liquid formulations on the release of a model substance, methylene blue (MB), from pellets coated with Eudragit ® RS 30 D. The microcrystalline cellulose pellets were layered with MB before coating with aqueous dispersions of Eudragit ® RS 30 D using a Wurster-type fluidized bed coater. The coating processes and conditions were validated and optimized before the final coating. The uncoated and coated pellets were characterized for their size, MB content, morphology and MB release. The results demonstrated that a stable coating process can be developed to produce repeatable batches of pellets. The film thickness was calculated and found to be similar to those observed from scanning electron microscope. The increased annealing time led to a more coherent film. The drug release was found to vary depending on the duration of annealing time and the addition of lactose. Addition of lactose gave a faster MB release and without any initial lag period in the release profile whereas the increased annealing time slowed down the MB release and increased the lag period.