Determination of Starch in Tobacco with Iodine Colorimetry

Starchisanimportantcarbohydrate ,themajorityofstarchinfreshtobaccoconvertsintoreducingsugarduringcuring,theresidualstarchincuredtobaccohasnegativelyeffectsontobacco’ssmokingquality[1- 5] ,soitmakessensetodeterminethecontentofstarchincuredtobaccoandcigarettes However,thestarchintobaccohaslongbeenconsideredoneofthetobaccocomponentshardtobedeter minedduetoisolation Thecommonmethodsofdeterminingstarchinplantsarebasedonthehydrolysisofstarchbyacidorenzymeandmeasurereducingsugars[6 - 7] Nevertheles…     

Preparation and stability of the inclusion complex of astaxanthin with hydroxypropyl-β-cyclodextrin

The inclusion complex of astaxanthin (ASX) with hydroxypropyl-β-cyclodextrin (HP-β-CD) was prepared. Infrared spectroscopy (IR) proved the formation of the inclusion complex. The water solubility of the inclusion complex was >1.0 mg/ml, which is much better than that of ASX. The solid state thermal behaviour of the inclusion complex was investigated by thermogravimetric/differential thermal analysis (TG/DTA). The starting decomposition temperature of ASX was enhanced to about 290 °C. The stability of the inclusion complex in solution was also tested. Forming of the inclusion complex greatly enhanced the stability of ASX against light and oxygen. Furthermore, the release of ASX from the inclusion complex was controlled.     

Preparation of Soybean Protein Concentrate with Mixed Solvents of Hexane－Aqueous Alcohol

Preparation of soybean protein concentrate with the mixed solvents of hexane-aqueous alcohol was studied in this paper.The optimum technology parameters were obtained by orthogonal tests.The results of experiments showed that the qualities of the product were good not only on taste of the product were good not only on tasted and color,but also on high solubility-NSI value was 48.80%.     

Texture properties of rice cakes made of rice flours treated with 4-α-glucanotransferase and their relationship with structural characteristics

Rice flours were treated using a thermostable 4-α-glucanotransferase (GTase) from Thermus aquaticus for 1, 3, and 48 h. Molecular weight of modified rice starch rapidly decreased within 1 h of reaction, then slowed down. As the reaction proceeded, the proportions of short (<DP 11) and long (>DP 30) branched chains of modified starch increased, whereas the proportion of medium chains decreased. Rice cakes were prepared with native and GTase-treated rice flours (substitution at 5%) and kept for 3 and 21 h. Texture profile analysis indicated significantly increased hardness, adhesiveness, chewiness, and resilience in rice cakes containing treated rice flours. Sensory analysis revealed that the rice cakes containing 48 h-treated flour had significantly increased springiness, hardness, toughness, and adhesiveness during both storage periods. Meanwhile, it displayed the lowest starch-like attribute and crumbliness. These results suggested that the substitution for 48 h GTase-treated rice flour could retard the retrogradation of rice cakes.     

Affinity purification of 4-α-glucanotransferase through formation of complex with insoluble amylose

4-α-Glucanotransferases (αGTases) are useful enzymes to modify starch structure using their unique hydrolysis pattern and transglycosylation activity. In spite of lacking of a carbohydrate binding module, a thermostable aGTase from Thermus thermophilus (TTαGT) bound to insoluble amylose, leading to simple recovery of the enzyme-amylose complex using centrifugation. At a preparative scale, the recovery yield was 40.3% of the subjected free enzyme via collection of the complex twice. The complex exhibited improved thermostability, which shifted the optimum temperature from 70 to 80°C and increased the half-life at 90°C by three-fold compared with the free enzyme. Texture profile analysis of the gels made of modified starch by either free TTαGT or the complex revealed that the complex with double dosage showed the performance similar to free TTαGT in the modification of starch. In conclusion, the purification method described here would be useful due to easy scale-up and simple process without chromatographic process.     

Preparation of aqueous dispersion of β-carotene nano-composites through complex formation with starch dextrin

Aqueous dispersions of β-carotene nano-composite were prepared through a blending process with a dextrin of high amylose corn starch in immiscible phases of aqueous dextrin and organic β-carotene solutions and water solubility and stability against oxidation of β-carotene were examined. Gradual evaporation of organic solvent during the mechanical stirring allowed the formation of aqueous solutions in which β-carotene was homogeneously dispersed with dextrin. Proper control of the solid concentrations effectively induced the complex formation between dextrin and β-carotene whereas an excess amount of β-carotene (>8 mg) in a dextrin solution (200 mg in 50 mL) induced crystallization and precipitation of β-carotene. The complex particles showed an irreversible endothermic transition of V-amylose (via DSC). X-ray diffraction analysis, however, revealed that the complex had no typical V-type crystalline arrangement. Hydrodynamic size of the complex particles in the aqueous solution could be decreased to nano-scale (16–30 nm) by a mild ultrasonication. The nano-composite contained β-carotene at approximately 30% on a weight, with improved stabilities against oxidation and enzymatic digestion.     

Kinetic studies of heterogeneous reactions of polycyclic aromatic hydrocarbon aerosols with NO₃ radicals

Polycyclic aromatic hydrocarbons (PAHs) and their derivates are mutagenic and carcinogenic substances widely distributed in the atmospheric environment. In this study, effective rate constants for heterogeneous reactions of NO(3) radicals with five 4-ring PAHs [benzo[a]anthracene (BaA), chrysene (Ch), pyrene (Py), 1-nitropyrene (1-NP), and 1-hydroxypyrene (1-OHP)] adsorbed on suspended azelaic acid particles are investigated by a mixed-phase relative rate method with gas-phase isoprene as the reference substance. The concentrations of suspended PAH particles and gas-phase isoprene are monitored concurrently by a real-time vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS) and an online atmospheric gas analysis mass spectrometer, respectively. The obtained effective rate constants for the reactions of BaA, Ch, Py, 1-NP, and 1-OHP particles with NO(3) radicals are 4.3 × 10(-12), 4.0 × 10(-12), 6.4 × 10(-12), 1.3 × 10(-12), and 1.0 × 10(-11) cm(3)·molecule(-1)·s(-1), respectively, and their corresponding atmospheric lifetimes range from several minutes to half an hour at the NO(3) radical concentration of 5 × 10(8) molecules·cm(-3). In addition, the NO(3) uptake coefficients on particulate PAHs are estimated according to the consumption of PAHs under the exposure of NO(3) radicals. The experimental results of these heterogeneous reactions in the aerosol state provide supplementary knowledge for kinetic behaviors of airborne PAHs particles.     

Effect of combined treatment of hydrolysis and polymerization with transglutaminase on β-lactoglobulin antigenicity

The effect of combined treatments of hydrolysis with different proteases, and subsequent polymerization with transglutaminase on the antigenic activity of β-Lg was studied. For the hydrolysis of β-Lg using Alcalase, Neutrase or bromelain, the reaction conditions were 3?% β-Lg and enzyme:substrate 25?U?g^?1 of protein, as was defined using factorial study. Under these conditions, the degree of hydrolysis (DH) of the hydrolysates was 12.6?% when obtained with Alcalase and approximately 4?% with Neutrase or bromelain. Post-hydrolysis polymerization did not result in an increase in molecular mass of the protein, but these samples presented a lower DH, determined by trinitrobenzenosulfonic acid (TNBS) method, suggesting that polymerization had occurred. Hydrolysis with the three enzymes reduced the β-Lg antigenicity, as evaluated by ELISA and immunoblotting analyses. The IgE-binding responses were practically null (<9?μg?mL^?1), 22.82 and 55.73?μg?mL^?1 towards the hydrolysates obtained with Alcalase, bromelain, and Neutrase, respectively. The post-hydrolysis polymerization increased or had no significant effect (P?≥?0.05) on the antigenic response of the hydrolysates.     

Preparation,characterisation and activity of the inclusion complex of paeonol with β-cyclodextrin

The inclusion complex of β-cyclodextrin (β-CD) and paeonol (2′-hydroxy-4′-methoxyacetophenone, PAE) was synthesised and characterised by thermal gravimetric analysis (TGA) and two-dimensional rotating frame spectroscopy (2D ROESY). The antioxidant activity and tyrosinase inhibition activity were also studied. The TGA results indicated that the thermal stability of PAE was improved when it was included with β-CD. Based on the 2D ROESY analysis, an inclusion structure of the PAE–β-CD complex was proposed, in which PAE penetrated β-CD in a tilted manner due to the interaction of intermolecular hydrogen bonds between PAE and β-CD. The complex of PAE with β-CD increased the antioxidant activity and tyrosinase-inhibiting activity of PAE.     

Glycation of whey protein with dextrans of different molar mass: Effect on immunoglobulin E–binding capacity with blood sera obtained from patients with cow milk protein allergy

A growing concern around the world is the number of people who are suffering from food protein allergies. One potential approach to decrease protein allergenicity is to block IgE-binding epitopes of the protein allergen by attachment of polysaccharides via the Maillard reaction (i.e., glycation). Protein glycation has been extensively studied to modify various functional properties. We wanted to examine whether glycates could reduce IgE binding in patients with cow milk protein allergy and to explore how the size (molar mass; M_W) of the polysaccharide affects this IgE-binding capacity. Glycation was performed using the initial step of the Maillard reaction performed in aqueous solutions. The specific goal of this study was to reduce the IgE-binding capacity of whey protein isolate (WPI) through glycation with dextran (DX). Blood sera were obtained from 8 patients who had been diagnosed with cow milk protein allergy, and a composite sera sample was used for IgE-binding analysis by the ImmunoCap (Phadia, Uppsala, Sweden) method. The WPI was glycated with DX of M_W ranging from 1 to 2,000 kDa, and the M_W of purified glycates was determined using size-exclusion chromatography coupled with multiangle laser light scattering. The WPI to DX molar ratios in the glycates made from DX that had M_W values of 1, 3.5, 10 (G10), 150, 500, and 2,000 kDa were 1:4, 1:3, 1:2, 1:1.5, 1:1, and 1:1, respectively. With the increase in the M_W of DX, there was an increase in the M_W values of the corresponding glycates but a decrease in the number of bound DX. The WPI-DX glycates had lower whey protein IgE-binding capacity than native WPI, with the lowest IgE-binding capacity obtained in the G10 glycate. The DX binding ratios and morphology results from atomic force microscopy images suggested that glycation of WPI with small-M_W DX resulted in extensive protein surface coverage, probably due to the attachment of up to 4 DX molecules per whey protein. The lower IgE binding of the G10 glycate was likely due to greater steric hindrance (or a physical barrier) at the surface of the protein. In summary, our results demonstrate that glycating WPI with DX via Maillard reaction can potentially be used to decrease the allergenicity of whey protein.     

Preparation and characterization of the inclusion complex of hypocrellin A with hydroxypropyl-β-cyclodextrin

Hypocrellin A (HA) is a naturally occurring perylenequinone pigment with bright red colour. The inclusion complex of HA with hydroxypropyl-β-cyclodextrin was prepared successfully by lyophilization method for the first time. Phase solubility studies indicated that the inclusion complex was formed with possible stoichiometry of 1:1. The apparent stability constants and the thermodynamic parameters such as enthalpy change (∆H), entropy change (∆S) and Gibbs free energy (∆G) were calculated in the range of 25–45 °C. The values of apparent stability constants decrease with the increasing of temperature. The thermodynamic results showed that the inclusion process was an exothermic and enthalpy-driven process accompanied with a negative entropic contribution. The formation of inclusion complex was also conformed by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry and spectroscopic studies. The inclusion complex showed much better water solubility and dissolution property than the free HA. Therefore, the inclusion complex can be used to expand the application of HA in food, feed and pharmaceutical industries.     

The viabilities of cells in cultures of Escherichia coli growing with formation of filaments at 6 °C

Cold adapted, exponential phase cells of three strains of Escherichia coli were incubated at 6 °C for 10 days. Cells in all cultures grew by elongation, with formation of filaments to different extents, but with generally only small changes in the numbers of colony forming units (cfu). At later incubation times some cells of all lengths were identified as dead by LIVE/DEAD staining, with cell wall damage being apparent in some cells stained as dead but not in cells stained as live. When samples of cultures were incubated at 37 °C for 2h, the numbers of cfu of two strains (ATCC 11775 and ATCC 23739) increased similarly and were not affected by the time of prior exposure to 6 °C. When incubated at 37 °C, the numbers of cfu of the other strain (8WT) increased less after incubation at 6 °C for 1, 2 or 3 days than when transferred to 37 °C from 15 °C. After>3 days at 6 °C numbers of strain 8WT were reduced after incubation at 37 °C for 2h. The findings show that in cultures of E. coli elongating at 6 °C, elongating cells and filaments do not divide; and cells of all lengths lose viability at similar rates. Also, the findings indicate that substantial fractions of cells in cultures elongating at refrigerator temperatures are inactivated by an abrupt change of temperature to 37°C.     

Interaction of modified tail-anchored proteins with liposomes: effect of extensions of hydrophilic segment at the COOH-terminus of holo-cytochromes b₅

A group of membrane proteins having a single COOH-terminal hydrophobic domain capable of post-translational insertion into lipid bilayer is known as tail-anchored (TA) proteins. To clarify the insertion mechanism of the TA-domain of human cytochrome b(5) (Hcytb5) into ER membranes, we produced and purified various membrane-bound forms of Hcytb5 with their heme b-bound, in which various truncated forms of NH(2)-terminal bovine opsin sequence were appended at the COOH-terminus of the native form. We analyzed the integration of the TA-domains of these forms onto protein-free liposomes. The integration occurred efficiently even in the presence of a small amount of sodium cholate and, once incorporated, such proteoliposomes were very stable. The mode of the integration was further analyzed by treatment of the proteoliposomes with trypsin either on the extravesicular side or on the luminal side. LC-MS analyses of the trypsin digests obtained from the proteoliposomes indicated that most of the C-terminal hydrophilic segment of the native Hcytb5 were exposed towards the lumen of the vesicles and, further, a significant part of the population of the extended C-terminal hydrophilic segments of the modified Hcytb5 were exposed in the lumen as well, suggesting efficient translocation ability of the TA-domain without any assistance from other protein factors. Present results opened a route for the use of the C-terminal TA-domain as a convenient tool for the transport of proteins as well as short peptides into artificial liposomes.     

Reactions of phenolic substances with lysozyme — physicochemical characterisation and proteolytic digestion of the derivatives

Lysozyme was modified by covalent attachment of selected phenolic compounds (m-, o-, p-dihydroxybenzenes, ferulic and gallic acid) at pH 9. The derivatives formed were characterized in terms of their physicochemical and digestion properties. The derivatization was accompanied by a reduction of lysine and tryptophan residues. Moreover, the solubility of the derivatives decreased over a broad pH range and the derivatization increased the hydrophobicity. The isoelectric points were shifted to lower pH values and formation of high molecular weight fractions occurred. In vitro experiments showed that, the peptic digestion of the derivatized lysozyme was adversely affected, whereas the tryptic, chymotryptic and pancreatic hydrolysis seemed to be favoured. The lytic activity of all the resulting lysozyme derivatives was reduced.     

Assessment of the antioxidative potential of dietary supplementation with α-tocopherol in low-nitrite salami-type sausages

The objective of this study was to determine the effects of dietary α-tocopherol supplementation to pigs on the lipid stability of nitrite-reduced salami-type sausages (custom-produced for this study). Fourteen crossbred pigs were divided into two equal groups. The control group (CG) was fed a basal diet containing 34ppm α-tocopherol, and the experimental group (EG), a diet supplemented with 364ppm α-tocopherol, both for 35 days. After slaughter, salami-type sausages were produced with the addition of different nitrite levels in the curing salt (100, 50, 25 and 0ppm), ripened for four weeks, sliced, and packaged under a protective atmosphere (80 parts N(2) to 20 parts CO(2)). The packed products were stored for eight weeks under simulation of the usual conditions in self-service shelves with permanent lighting (9°C, 200 lux). The sausages were regularly assessed for their oxidative status (thiobarbituric acid-reactive substances, fatty acid pattern) and the amount of α-tocopherol, and by sensory evaluation. In the EG sausages, α-tocopherol concentrations were twice as high and TBARS were lower than in the CG sausages. The α-tocopherol in EG prevented the loss of unsaturated fatty acids during storage. Sausages of EG containing 100ppm nitrite had the longest sensory stability. However, the biochemical parameters did not indicate that nitrite had any effect on the antioxidative potential of the sausages.     

Effect of partial replacement of sodium chloride with potassium chloride on the characteristics of Minas Padrão cheese

Partial replacement of NaCl by KCl (25% and 50%) in Minas Padrão cheese was investigated for the physicochemical characteristics, sensory evaluation, fatty acid profile, and texture parameters. Salt replacement did not affect the moisture content, protein, fat, ash, water activity, chloride, pH, and proteolysis. A significant reduction in sodium levels was observed, ranging from 369.12 mg 100 g⁻¹ to 210.05 mg 100 g⁻¹, while the control treatment (100% NaCl) presented 608.67 mg 100 g⁻¹. Proteolysis indexes increased throughout ripening. Hardness and chewiness increased, as a result of pH reduction and syneresis in cheese, which caused a decrease in moisture content. The fatty acid profile was affected by sodium reduction, with an increase in short chain, medium-chain, and polyunsaturated fatty acids. In relation to the acceptance test, no significant differences were observed for the cheese with a substitution of 25% sodium chloride with potassium chloride when compared with the control.     

Phase solubility studies of terpineol with β-cyclodextrins and stability of the freeze-dried inclusion complex

In present work, phase solubility analysis were conducted for studying the solubility of terpineol, a natural flavor compound with antifungal and disinfectant action, in 2-hydroxypropyl-β-cyclodextrin (HBCD) and in β-cyclodextrin (BCD) aqueous solutions and for calculating the thermodynamic parameters involved in the complex formation. Physical properties of the freeze-dried complexes were also evaluated as a function of water content and storage time. The solubility of terpineol increased linearly as the concentration of BCD or HBCD was increased, confirming the 1:1 stoichiometry of the complex. The negative value of the enthalpy and of the Gibbs energy demonstrated that the process is exothermic and spontaneous. Since complexation gives more ordered systems, the negative value obtained for the entropy change confirms the encapsulation of terpineol both in HBCD and BCD. The water adsorption data and glass transition values obtained revealed that complexation involves the displacement of water molecules from the cavity of the CDs by the guest compound that is being included.     

Potentiometric titration for determination of amylose content of starch – A comparison with colorimetric method

Amylose, the amount of which varies significantly depending on the source, is one of the key components of starch. The proportion of the essentially linear amylose and the highly branched amylopectin greatly influences the physico-chemical properties of starch. In this study, potentiometric titration using an auto-titrator and colorimetric methods were compared for determining amylose contents of a variety of starch samples. Potentiometric titration results for starches from a variety of botanical sources were within the reported literature ranges while the colorimetric method seemed to overestimate amylose content.     

Discrimination of teas with different degrees of fermentation by SPME–GC analysis of the characteristic volatile flavour compounds

As tea is traded all over the world, it is necessary for both customs officers and business investigators to develop an easy and reliable method to discriminate teas from each other. A total of 56 kinds of various green, Oolong, and black teas were collected from different countries and markets, and their catechin contents and volatile flavour compounds (VFC) were compared by analyses, using HPLC and solid-phase microextraction–gas chromatograph (SPME–GC). It was found that neither total catechin nor individual catechin contents in green and Oolong teas were significantly different among the samples investigated, but the fermentation processes altered the profiles of tea VFC. Because many of the individual VFC did not change in response to the fermentation levels, several VFC in combination might be more reliable than a single compound to identify broader ranges of teas. A total concentration of five VFC, trans-2-hexenal, benzaldehyde, methyl-5-hepten-2-one, methyl salicylate, and indole, was shown to be able to discriminate clearly unfermented and fermented teas, while that of trans-2-hexenal and methyl salicylate together supplied an index to differentiate semi- and fully-fermented teas. In addition, the SPME–GC analysis was also able to distinguish real jasmine teas from fake jasmine teas based on the disappearance of some grassy/green odorants.