Aggregates and gel network structure of globin hydrolysates

A gel with excellent functional properties was prepared successfully using the hydrolysates of globin. In the present study, the structures of intermediate aggregates and gel network were observed directly with an electronic microscope. It was shown clearly that the intermediate aggregates were in a thin rod shape with a length of 130--140 nm, which was in good accordance with the results of the light scattering obtained in a previous study. The diameter of intermediate aggregates was 4--5 nm. Each unit of the intermediate aggregate was composed of beta-chain and peptide beta-1 in a ratio of 1:1. Its molecular weight was 26922 Da, and it had a diameter of 4.1 nm. The thin rod-shaped aggregates were formed with units through the hydrophobic interaction. The length of intermediate aggregate was >30--33 times the diameter. Furthermore, the cross-linked structure formed by peptide alpha-1 and the thin rod-shaped aggregates was also confirmed by the photography of the electronic microscope. These results supported the model proposed in previous papers as proper to depict exactly the formation and structure of the gel network of globin hydrolysates.     

Inhomogeneities in the chemical structure of sugarcane bagasse lignin

Sequential treatments of dewaxed bagasse with distilled water, 0.5 M NaOH, 0.5, 1.0, 1.5, 2.0, and 3.0% H(2)O(2) at pH 11.5, and 2 M NaOH at 55 degrees C for 2 h solubilized 2.8, 52.5, 14.9, 3.3, 5.5, 5.0, 2.8, and 2.2% of the original lignin, respectively. The eight isolated lignin fractions were subjected to a comprehensive structural characterization by UV, FT-IR, and (1)H and (13)C NMR spectroscopies and thermal analysis. The nitrobenzene oxidation method was also applied to the in situ lignins. The seven lignin fractions, isolated successively with alkali and alkaline peroxide, were all SGH-type lignins, with a small amount of esterified p-coumaric acid and mainly etherified ferulic acid. No significant differences were found in the weight-average molecular weights (1680-2220 g/mol) of the seven alkali and alkaline peroxide dissolved lignins. However, the first four lignin fractions, isolated with 0.5 M NaOH and 0.5, 1.0, and 1.5% H(2)O(2) at pH 11.5, were rich in syringyl units and contained large amounts of noncondensed ether structures, whereas the last three lignin fractions, isolated sequentially with 2.0 and 3.0% H(2)O(2) at pH 11.5 and 2 M NaOH at 55 degrees C for 2 h, had a higher degree on condensation and were rich in guaiacyl lignins.     

Specificity of papaya lipase in esterification with respect to the chemical structure of substrates

Esterification, catalyzed by papaya (Carica papaya) lipase (CPL), was studied with various alcohols and carboxylic acids under competitive conditions. Acids studied were straight-chain saturates of different chain lengths, with octanoic acid as the reference. Alcohols chosen were aliphatic straight-chain, branched, secondary, tertiary, terpene, and aromatic alcohols of different chain lengths, using 1-hexanol as the reference. The initial reaction rate increased with increasing chain length of the acid from C4:0 to C18:0, followed by a slight decrease with C20:0. In the case of alcohols, an optimum chain length of 8 carbon atoms was obtained for the straight-chain aliphatic group (C2 to C16). Ethanol, 1-propanol, and secondary and tertiary alcohols showed rather low reactivity. Branching of the alcohols was found not to affect the reactivity in esterification; among the terpenes, beta-citronellol [(2E)-3, 7-dimethyl-6-octenol] and geraniol [(2E)-3,7-dimethylocta-2, 6-dien-1-ol] were found to be more reactive than nerol [(2Z)-3, 7-dimethylocta-2,6-dien-1-ol]. The highest reaction rate was found for the aromatic benzyl alcohol (phenylmethanol).     

Synthesis and screening of anilides having olefinic and alkyl moiety in the side chain as chemical hybridizing agents for wheat (Triticum aestivum L.)

Induction of male sterility by deployment of chemical hybridizing agents (CHAs) holds immense potential in heterosis breeding of wheat. A total of 21 anilides having different aromatic substitutions and side-chain variation were synthesized and screened as CHAs on three genotypes of wheat viz., PBW 343, HW 2046, and HD 2733, at winter season. Various anilides having vinyl moiety in the acyl side chain were synthesized by condensation between substituted anilines with different esters or acid chlorides. Another lead in the form of N-alkyl anilines also became evident. The percent male sterility data caused by CHAs revealed the significant contribution of anilides containing vinyl double bond incorporated in the form of closed ring structure viz., furyl moiety as the side chain. 4'-Fluoro-furyl anilide (1) and 4'-bromo-furyl anilide (2) are found to be promising lead CHAs for the design of highly active molecules. QSAR analysis revealed a direct relationship of field effect exemplified by the Swain-Lupton constant F(p) for the aromatic substitution but an inverse relationship of molar refractivity MR for the side chain. The negative influences of parachor for the acyl domain have been underlined. The real guiding principle for selectivity of CHA action was found to be the pi value. The CHAs act by mimicking UDP-glucose, the key substrate in the synthesis of callose, or lead to an imbalance in acid-base equilibrium in pollen mother cells resulting in dissolution of callose wall by premature callase secretion.     

Daidzein as an antioxidant of lipid: effects of the microenvironment in relation to chemical structure

Isoflavone daidzein (D, pK a1 = 7.47 +/- 0.02 and pK a2 = 9.65 +/- 0.07) was, through a study of the parent compound and its three methyl anisol derivatives 7-methyldaidzein (7-Me-D, pK a = 9.89 +/- 0.05), 4'-methyldaidzein (4'-Me-D, pK a = 7.43 +/- 0.03), and 7,4'-dimethyldaidzein (7,4'-diMe-D), found to retard lipid oxidation in liposomal membranes through two mechanisms: (i) radical scavenging for which the 4'-OH was more effective than the 7-OH group in agreement with the oxidation potentials: 0.69 V for 4'-OH and 0.92 V for 7-OH versus Ag/AgCl in acidic solution and 0.44 V for 4'-O(-) and 0.49 V for 7-O(-) in alkaline solution and (ii) change in membrane fluidity through incorporation of the isoflavones, in effect hampering radical mobility. The radical scavenging efficiency measured by the rate of the reaction with the ABTS(*)(+) in aqueous solution followed the order D > 7-Me-D > 4'-Me-D > 7,4'-diMe-D, as also found for antioxidant efficiency in liposomes when oxidation was initiated with the water-soluble AAPH radical and monitored as the formation of conjugate dienes. For oxidation initiated by the lipid-soluble AMVN radical, the antioxidant efficiency was ranked as 4'-Me-D > D > 7,4'-diMe-D > 7-Me-D, and change in fluorescence anisotropy of fluorescent probes bound to the membrane surface or inside the lipid bilayer confirmed the effects of isoflavones on the membrane fluidity, especially for 7,4'-diMe-D.     

Role of maize hybrids and their chemical composition in Fusarium infection and fumonisin production

This study was designed to investigate the role of hybrids in maize Fusarium section Liseola interaction and fumonisin production, with particular emphasis on the occurrence and accumulation of hidden fumonisins in maize (masking phenomenon). In this 2 year study, naturally infected field crops were chosen with 10 maize hybrids, six of them grown in both years. Maize samples collected in 2010 showed a higher incidence of fungal infection as well as higher fumonisin contamination than those obtained in 2009 but a very similar incidence of F. section Liseola. Fumonisin masking was confirmed in raw maize, with a lower amount of hidden forms as compared to free fumonisins detected in the year with higher contamination. The chemical composition of the different hybrids was determined and correlated with the contamination data: the results obtained highlight the main role of fatty acids, with a higher fumonisin contamination in hybrids showing a higher linoleic acid content and a higher masking action in hybrids with higher oleic to linoleic ratio. These results represent a good basis to explain maize hybrid susceptibility to F. section Liseola infection, fumonisin contamination, and masking not related to a specific commercial hybrid but extendable to all hybrids.     

Role of chemical constituents of wheat straw and pig slurry on their decomposition in soil

Carbon mineralization and microbial biomass content of wheat straw (WS), pig slurry (PS) and their mixture (WSPS), either intact or with extraction of soluble substances (–SS) or soluble substances plus hemicellulose (–SSH), added to soil, were monitored over 230 days in a laboratory incubation experiment. The WSPS showed a CO₂ release of up to 23% above that predicted by summing the CO₂ evolved from WS and PS. Of the several kinetic models tested to describe the mineralization process, a double exponential model best described the C mineralization of all the materials, both intact and with extractions. The extraction of the labile substances from WS, PS and WSPS lowered the values of the rapidly mineralizable C and of the amount of microbial biomass. The organic fraction of WS was found to be almost completely represented by mineralizable carbon, while PS and WSPS showed only 62% of mineralizable carbon. In spite of this, after 8 months, about half of the initial amount of the organic C in the intact residues still remained unmineralized. Received: 29 October 1996     

Analysis of anthocyanins in rat intestinal contents--impact of anthocyanin chemical structure on fecal excretion

Absorption of dietary anthocyanins is limited; however, fecal anthocyanin excretion has been rarely studied. We developed a method for extraction and analysis of fecal anthocyanins. Aqueous methanol (60%) maximized extraction efficiency (approximately 88%). Severe anthocyanin degradation (monitored by high-performance liquid chromatography) was observed in feces stored at -18 degrees C; therefore, storage time should be minimized and lower temperatures used. Fecal and cecal content samples were collected from 32 rats receiving either chokeberry, bilberry, grape-enriched (3.85 g monomeric anthocyanin per kg diet), or control diet for 14 weeks. Fecal anthocyanin concentrations were significantly different among groups (0.7/1.8/2.0 g/kg wet feces, chokeberry/bilberry/grape). Anthocyanin profiles of cecal contents and feces were similar. Losses in the intestinal contents were high for anthocyanin glucosides, moderate for galactosides, and negligible for arabinosides or xylosides. Acylation or diglucosylation enhanced anthocyanin stability. High anthocyanin concentration in the fecal content may favor anthocyanin absorption into the colon epithelial cells, resulting in potential health benefits.     

Identification of two novel pigment precursors and a reddish-purple pigment involved in the blue-green discoloration of onion and garlic

By using a model reaction system representing blue-green discoloration that occurs when purees of onion (Allium cepa L.) and garlic (Allium sativum L.) are mixed, we isolated two pigment precursors (PPs) and a reddish-purple pigment (PUR-1) and determined their chemical structures. PPs were isolated from a heat-treated solution containing color developer (CD) and either l-valine or l-alanine, and their structures were determined as 2-(3,4-dimethylpyrrolyl)-3-methylbutanoic acid (PP-Val), and 2-(3,4-dimethyl-1H-pyrrolyl) propanoic acid (PP-Ala), respectively. Next, PUR-1 was isolated from a heat-treated solution containing PP-Val and allicin, and its structure was determined as (1E)-1-(1-((1S)-1-carboxy-2-methylpropyl)-3,4-dimethyl-1H-pyrrol-2-yl)-prop-1-enylene-3-(1-((1S)-1-carboxy-2-methylpropyl)-3,4-dimethyl-1H-pyrrol-2-ylidenium). The structure of PUR-1 suggested that PP molecules containing a 3,4-dimethyl pyrrole ring had been cross-linked by an allyl group of allicin to form conjugated pigments. While PUR-1 is a dipyrrole compound exhibiting a reddish-purple color, a color shift toward blue to green can be expected as the cross-linking reaction continues to form, for example, tri- or tetrapyrrole compounds.     

Human IgE binding to the glycosidic moiety of bovine kappa-casein

IgE ability for recognizing milk proteins was assayed in the serum of an adult atopic patient who outgrew cow milk allergy in early childhood. A number of protein species included in casein from bovine milk were detected by human IgE in immunoblotting experiments. Comparing these results with those obtained from an analysis using antibody preparations specifically directed toward the different casein fractions, IgE-reactive bands were identified as isoforms of kappa-casein. IgE-reactive protein was not present in neither bovine cheese, regardless of cheese-making technology and time ripening, nor milk from any other dairy animal, such as ewe, goat, and water buffalo. Chemical deglycosylation of protein bands immobilized onto nitrocellulose proved that the glycosidic moiety of bovine kappa-casein was principally involved in IgE recognition.     

Systematic studies on the chemical structure and umami enhancing activity of Maillard-modified guanosine 5'-monophosphates

Recent investigations on taste active principles in nucleotide rich yeast extracts led to the discovery of (R)- and (S)-N(2)-(1-carboxyethyl)-guanosine 5'-monophosphate as previously not reported umami enhancing molecules formed upon the Maillard reaction of guanosine 5'-monophosphate (5'-GMP) with dihydroxyacetone and glyceraldehyde, respectively. In the present study, systematic Maillard-type model reactions were performed with 5'-GMP and a homologous series of monosaccharides exhibiting a C(3)- to C(6)-carbon skeleton as well as with the reducing disaccharide maltose in the presence of an amino acid. By preparative RP-HPLC, various (R)- and (S)-N(2)-(1-carboxyalkyl)-guanosine 5'-monophosphates and (R)- and (S)-N(2)-(1-alkylamino)carbonylalkyl)guanosine 5'-monophosphates were isolated and identified by means of LC-MS, LC-TOF-MS, and 1D/2D-NMR spectroscopy. Sensory evaluation of these Maillard products revealed β-values for umami enhancement between 0.06 and 7.0 and identified a strong influence of the stereochemistry as well as the chain length of the N(2)-substituent on the umami enhancing activity. For all of the compounds evaluated, the (S)-configured isomers showed higher taste impact, whereas the (R)-isomers showed only marginal β-values, thus underlining the stereospecifity of the umami taste receptor binding site.     

Synthesis and antiviral activities of amide derivatives containing the alpha-aminophosphonate moiety

Starting from (substituted-)benzaldehydes, the title compounds 6 were synthesized through five step reactions. Benzaldehydes were treated with ammonium hydroxide, followed by dialkyl phosphite, to give dialkyl N-(arylmethylene)-1-amino-1-aryl methylphosphonates ( 3). Phosphonates 3 were then easily hydrolyzed to give dialkyl 1-amino-1-aryl-methylphosphonates 5. Target compounds 6 were then obtained by the reaction of 5 and substituted benzoic or cinnamic acid. Their structures were clearly verified by spectroscopic data (IR, 1H, 13C, and 31P NMR, and elemental analysis). These compounds were shown to be antivirally active in the bioassay. It was found that title compounds 6g, 6l, and 6n had the same inactivation effect of TMV (EC 50 = 54.8, 60.0, and 65.2 microg/mL, respectively) as commercial product Ningnanmycin (EC50 = 55.6 microg/mL). To the best of our knowledge, this is the first report on the synthesis and antiviral activity of amide derivatives containing an alpha-aminophosphonate moiety.     

Design, synthesis, structure, and acaricidal/insecticidal activity of novel spirocyclic tetronic acid derivatives containing an oxalyl moiety

A series of novel spirocyclic tetronic acid derivatives containing an oxalyl moiety was designed and synthesized via the key intermediate 3-(2,4,6-trimethyl)-2-oxo-1-oxaspiro[4.4]-decyl-3-en-4-ol. The target compounds were identified by (1)H NMR and elemental analysis or high-resolution mass spectrum (HRMS). The results of bioassays indicated that most of the target compounds possessed excellent acaricidal activities against carmine spider mite larvae and eggs. Especially, diisopropylamino oxalyl compound 7g and piperidine oxalyl compound 7h were 1.4- and 2.3-fold as high as the activities of commercial Spiromesifen, respectively, against spider mite eggs. Moreover, most of the target compounds exhibited insecticidal activities against Lepidoptera pest. Interestingly, compounds containing alkylamino-substituted oxalyl moiety showed obvious selectivity between spider mite larvae and eggs because the activities against spider mite eggs of 7g and 7h were 25-fold those against spider mite larvae, whereas Spiromesifen had no significant differences in these activities. This meant that the introduction of an oxalyl moiety to spirocyclic tetronic acid might lead to novel biological activity characteristics.     

Linking peanut allergenicity to the processes of maturation,curing, and roasting

The processes of peanut maturation, curing, and roasting are known to have an important role in peanut flavors. One of these processes (i.e., roasting) has been found to have an effect on allergenicity. To determine if the other processes (i.e., maturation and curing) affect allergenicity, mature and immature roasted peanuts and peanuts cured at different temperatures (35-77 degrees C) were, respectively, tested for IgE binding and advanced glycation end adducts (AGEs). Peanuts with and without stress proteins, which are associated with peanut maturation and curing, were also tested. Results showed that mature roasted peanuts exhibited a higher IgE binding and AGEs level than immature roasted peanuts. Curing temperatures between 35 and 60 degrees C gave no difference in the profiles. However, a higher curing temperature (i.e., 77 degrees C) exhibited a profile of higher levels of AGEs and IgE binding. These levels were higher in peanuts with stress proteins than without stress proteins. Roasting increased stress protein level and IgE binding. From these results, the processes of maturation and curing, in conjunction with roasting, may be associated with allergenicity, suggesting that these processes may lead to changes in the allergenic properties of peanuts.     

Investigation of thermal decomposition as the kinetic process that causes the loss of crystalline structure in sucrose using a chemical analysis approach (part II)

High performance liquid chromatography (HPLC) on a calcium form cation exchange column with refractive index and photodiode array detection was used to investigate thermal decomposition as the cause of the loss of crystalline structure in sucrose. Crystalline sucrose structure was removed using a standard differential scanning calorimetry (SDSC) method (fast heating method) and a quasi-isothermal modulated differential scanning calorimetry (MDSC) method (slow heating method). In the fast heating method, initial decomposition components, glucose (0.365%) and 5-HMF (0.003%), were found in the sucrose sample coincident with the onset temperature of the first endothermic peak. In the slow heating method, glucose (0.411%) and 5-HMF (0.003%) were found in the sucrose sample coincident with the holding time (50 min) at which the reversing heat capacity began to increase. In both methods, even before the crystalline structure in sucrose was completely removed, unidentified thermal decomposition components were formed. These results prove not only that the loss of crystalline structure in sucrose is caused by thermal decomposition, but also that it is achieved via a time-temperature combination process. This knowledge is important for quality assurance purposes and for developing new sugar based food and pharmaceutical products. In addition, this research provides new insights into the caramelization process, showing that caramelization can occur under low temperature (significantly below the literature reported melting temperature), albeit longer time, conditions.     

Aging effect on the pigment composition and color of Vitis vinifera L. Cv. Tannat wines. Contribution of the main pigment families to wine color

Red wines made from Vitis vinifera L. cv. Tannat grapes are known to possess high contents of tannins and intense color, features that are responsible for the originality of these wines. This work aimed to study the evolution of the pigment composition and CIELAB color parameters as Tannat wines become older, as well as to establish the contribution to wine color of the main pigment families. Tannat wines produced in Uruguay from grapes of the same vineyard in six consecutive vintages (1998-2003) and Tannat grapes of the 2003 harvest were analyzed by means of HPLC-DAD-MS and UV-vis spectrometric techniques. The correlations between the different pigment families and the CIELAB parameters revealed the importance of the variations of the percentage, found in anthocyanins and flavanol-anthocyanin acetaldehyde-mediated condensation products (decrease) and pyranoanthocyanins and direct condensation products (increase), in the modification of the color from purple-red hues to more orange-red ones. The color suffered qualitative rather than quantitative changes, that is, the hue (h*ab) increased, whereas the chroma (C*ab) and lightness (L) did not show a defined trend with time.     

Effect of flavor compound chemical structure and environmental relative humidity on the binding of volatile flavor compounds to dehydrated soy protein isolates

Influence of flavor compound chemical structure, including functional group and stereochemistry, and environmental relative humidity (RH) on the binding of volatile flavor compounds to dehydrated soy protein isolates (SPIs) was evaluated by inverse gas chromatography. Binding of selected volatile flavor compounds differed slightly between SPIs of different origins. Results showed that the flavor compound chemical structure greatly determined its binding potential to SPIs. Binding of nonpolar flavor compounds (hydrocarbon) to soy proteins was attributed mainly to nonspecific van der Waals dispersion forces and was not affected by adsorbed water. The more polar flavor compounds (ester, ketone, aldehyde, and alcohol) exhibited both specific (hydrogen bonding, dipole forces) and nonspecific interactions, and their binding with soy proteins was greatly impaired by adsorbed water in the extremely low humidity region (approaching 0% RH). Further water uptake in the 30 to 50% RH region did not significantly affect the binding of polar compounds, although sorption of alcohol compounds (when present at high levels) further increased.     

Bioassay versus chemical analysis for chemical residues in soil: the eglin air force base experience

Conclusion  The analysis of soil residues by the use of bioassays and chemical analyses provided an insight into the nature of the chemical residues that persisted after the termination of the spray equipment test program in July 1970. The application of both methods proved valuable in deciding how to proceed with the environmental and ecological studies of the test site. Indeed these studies provided the foundation for the subsequent 15 years of scientific investigations of Test Area C-52. Fig 4. is an overview of the subsequent studies that occurred after the bioassay and chemical studies in 1969-1970. The Eglin Experience represents one the few available ‘classic studies’ of an entire ecosystem that has been massively contaminated with chemicals (in this case, herbicides) and followed for decades after the contamination [1].     

Influence of chemical characteristics in the development of soil colour

Factors responsible for the development of colour in reddish-brown basaltic soils of Malwa Plateau, India, were studied with the aid of multiple regression correlation analysis between the soil Munsell colour parameters and the chemical characteristics. Titanium and ferrous iron for soil “hue”, clay and organic matter for soil “value” were found to influence the development of colour in these soils. Partial regression analysis was carried out to assess the relative importance of individual factors in soil colour.     

Quantitation of selected odor-active constituents in dry fermented sausages prepared with different curing salts

The odor-active compounds of dry-fermented sausages with added nitrite or nitrate as curing agents were identified by gas chromatography-olfactometry (GC-O) applying the detection frequency (DF) method. The quantification of these compounds in the sausage was determined by multiple headspace solid-phase microextraction (multiple HS-SPME). There were no specific odor-active compounds related to the use of nitrite or nitrate although there were differences in the DF value of several compounds. The nitrite-added sausages presented higher DF values for ethanol, 1-hexanol, propanoic acid, 2-heptenal, and nonanal while the nitrate-added sausages had higher DF values for phenylacetaldehyde and 3-methyl-butanal. Eighteen compounds were quantified by multiple HS-SPME. Most of them were above their air detection thresholds, but only hexanal, heptanal, and 1-octen-3-ol were in a concentration higher than their oil threshold values. These compounds would probably be the main contributors to the aroma of fermented sausages.