Min Of Hydrolysis Research Articles

Changes in starch during malting of finger millet (Ragi, Eleusine coracana , Indaf-15) and its in vitro digestibility studies using purified ragi amylases

Malting of finger millet resulted in a decrease in its starch content and an apparent increase in its amylose value. Scanning electron microscopy studies of ungerminated and germinated starches showed a pattern of granular hydrolysis, which was dependent on the size and shape; big granules appeared to be more susceptible than small granules. Malting did not affect the relative viscosity of starches isolated from ragi malts. Purified α-1 amylase was found to hydrolyze germinated ragi starches (24, 48, 72 and 96 h) to an extent of 50–60%, whereas for α-2 and α-3 amylases it was in the range of 50–55% and 60–70% respectively. Amylose contents of starches did not have any visible effect on the extent of hydrolysis. Maltotetraose was the major oligosaccharide produced by these enzymes from all the germinated starches after 15 min of hydrolysis. Higher oligosaccharides (degrees of polymerization of 8 and above) underwent further degradation after 120 min hydrolysis.

Triglyceride Assay by Amperometric Microbial Biosensor: Sample Hydrolysis and Kinetic Approach

ABSTRACT A triglyceride assay based on triglyceride hydrolysis and glycerol detection was developed. Non-specific lipase isolated from Candida rugosa and intact Gluconobacter oxydans cells, containing membrane-bound glycerol dehydrogenase, were used to develop a biosensor. Two approaches were investigated: analysis of pre-hydrolysed samples and a kinetic approach. The sensor prepared from G. oxydans cells exhibited sensitive and fast response to glycerol: detection limit 20 μM (S/N=3), linear range up to 2 mM and response time 84 s (90% of steady-state). The triglyceride assay of pre-hydrolysed samples was based on a 20 min hydrolysis and determination of released glycerol by the biosensor. A calibration curve linear up to 12 mM was obtained for triolein samples. The kinetic approach was based on simultaneous glyceride hydrolysis and glycerol detection. Analysis time of 10 min, linear range up to 30 mM, and estimated detection limit of 50 μM were achieved using the kinetic approach. The kinetic triglyceride assay is not influenced by free glycerol present in a sample. Storage stability, expressed as a half life (50% of the initial response), was 7 days when trehalose was used as a stabiliser.

Functional Properties of Fish Protein Hydrolysate from Herring (Clupea harengus)

ABSTRACTRaw herring (Clupea harengus), a waste product from the roe industry, was hydrolyzed, using an endopeptidase preparation from Bacillus licheniformis. Aliquots were taken at 0, 5, 10, 20, 30, 45, and 60 min hydrolysis to measure the degree of hydrolysis. The functional properties tested were emulsifying activity index (EAI), foamability, and foam stability of the hydrolysate. At 36% hydrolysis, the herring hydrolysate presented good emulsifying stability (> 120 minutes) and an adequate foam expansion (142%), as compared to the soluble fraction from the unhydrolyzed control herring. The lipid content decreased considerably to 0.77% for the fish protein hydrolysate, while its protein content increased to 77%. The amino acid composition remained similar to that of the control.

Immunolocalization of a Purified Xylanase During Hydrolysis of Wheat Straw Stems

Hydrolysis of wheat stems and delignified wheat stems with a purified 20.7 kDa xylanase (EC 3.2.1.8) isolated from a Bacillus sp. yielded 18% and 70% of xylans, respectively. In order to evaluate the accessibility of the xylans and the extent of diffusion of the xylanase in wheat stems, antixylan and antixylanase polyclonal antibodies in conjunction with immunogold labeling and microscopic studies were used on stem fragments degraded by the xylanase. After 30 min of hydrolysis, the labeling of the xylanase was abundant for both lignified and delignified stems and occurred within all cell walls, demonstrating a fast penetration of xylanase in stem fragments. However, the distribution of immunolabel differed between the two types of straw. Xylanase was unevenly distributed in nondelignified straw, especially around the lumen side of cell walls and often grouped in clusters but homogeneous within delignified straw. Localization of xylans in both stem fragments showed that xylans were distributed homogeneousl...

Lactacystin, a Specific Inhibitor of the Proteasome, Inhibits Human Platelet Lysosomal Cathepsin A-like Enzyme

Lactacystin, the most specific inhibitor of the proteasome, strongly inhibited at pH 5.5 the activity of human platelet lysosomal cathepsin A-like enzyme. At a concentration as low as 1-5 μM it almost completely decreased the hydrolysis rate of cathepsin A specific substrates: Cbz-Phe-Ala and FA-Phe-Phe. This inhibition was probably due to the lactacystin intermediate β-lactone formed during 10 min hydrolysis at pH 8.0 since nonhydrolyzed inhibitor did not affect cathepsin A activity. Basing on similarities in the inhibitor sensitivity, pH optimum, and substrate preferences it is suggested that the cathepsin A-like activity may be involved in chymotrypsin-like activity of the proteasome.

Study of the use of a protease with the van Soest procedure

Several trials were performed to elaborate a method facilitating NDF filtration and to reduce analytical errors on feeds rich in proteins. Three pronases (P5147, 33635, Serva; 53702, Calbiochem) were compared at various concentrations. The pronase 53702 was retained to elaborate the NDF pretreatment procedure which includes 1–10 min of hydrolysis with distilled water, with 2–15 min of hydrolysis with 60 u of α-amylase (Termamyl 120 L) and 3–15 min hydrolysis with 100 μ of pronase 53702. Applied to a set of 20 various common ingredients this pretreatment largely facilitated the filtration. As results there were decreases of the NDF content (2.43% of dry matter) and of the residual N of NDF (0.50% of NDF).

Cyanide content of the leaves and stems of edible aroids

AbstractThe edible aroids taro (Colocasia esculenta), tannia (Xanthosoma violaceum), giant taro (Alocasia macrorrhizos), giant swamp taro (Cyrtosperma chamissonis) and elephant foot yam (Amorphophallus paeonifolius) have been shown to contain varying amounts of cyanide in their leaves and stems using a screening assay and a more accurate acid hydrolysis method. The cyanogenic glucoside triglochinin (previously identified in giant taro) was found to be less stable to acid hydrolysis (requiring only 15 min) compared with 50 min hydrolysis for linamarin and lotaustralian (from cassava) under the same experimental conditions. The amounts of cyanide present in the leaves (0‐3 mg HCN/100 g fresh weight) and in the stems (0—0.3 mg HCN/100 g fresh weight) of Colocasia and Xanthosoma are only about 1‐5% of that found in cassava leaves and tubers and are not a cause for concern for human nutrition. Cyrtosperma stems and Amorphophallus leaves contain only small amounts of cyanide. In contrast, all Alocasia varieties contained much more cyanide in leaves (2‐30 mg HCN/100 g fresh weight) and in stems (0.5‐4 mg HCN/100 g fresh weight).

Considerations on Some Structural and Physicomechanical Modifications in Synthesis of Micronized and Microcrystalline Cellulose for Pharmaceuticals

Abstract The aim of the paper is to present some aspects concerning the micronized celluloses obtained by hydrolysis and their use in the pharmaceutical field: the physicomechanical and structural properties of the starting materials (cotton-viscose staple mixture), microcrystalline cellulose characterization in connection with the end use, and the influence of the parameters (reaction time, temperature, acid concentration) on the hydrolytic process. The optimum values of the parameters are: above 35% H2SO4 concentration, 60°C temperature, and 60 min of hydrolysis. The reactions occur preferably in the amorphous phase of the cellulose. The fractions obtained do not differ as to their crystallinity or crystalline domain dimensions. The particularities in supermolecular structure of these fibers determine some behavior pecularities during the hydrolysis.

Permeabilization of mycolic-acid-containing actinomycetes for in situ hybridization with fluorescently labelled oligonucleotide probes.

The application of whole-cell hybridization using labelled oligonucleotide probes in microbial systematics and ecology is limited by difficulties in permeabilizing many Gram-positive organisms. In this investigation paraformaldehyde treatment, acid methanolysis and acid hydrolysis were evaluated as a means of permeabilizing mycolic-acid-containing actinomycetes prior to hybridization with a fluorescently labelled oligonucleotide probe designed to bind to a conserved sequence of bacterial 16S rRNA. Methods were evaluated on stationary-phase cultures of Gordona bronchialis, Mycobacterium fortuitum, Nocardia asteroides, N. brasiliensis, Rhodococcus equi, R. erythropolis, R. fascians, R. rhodochrous and Tsukamurella paurometabola, none of which could be probed following 4% (w/v) paraformaldehyde fixation. For comparison and to test the general applicability of mild acid pretreatments, Bacillus subtilis, Lactobacillus plantarum, Escherichia coli and Pseudomonas putida were also studied. The data showed that most of the mycolic-acid-containing organisms were successfully permeabilized by mild acid hydrolysis in 1 M HCl at 37 degrees C. Cells were treated for different lengths of time. In general, the mycolic-acid-containing organisms required between 30 and 50 min hydrolysis, whereas B. subtilis, E. coli and P. putida were rendered permeable in only 10 min. Interestingly, L. plantarum could not be permeabilized using acid hydrolysis even after 60 min exposure to 1 M HCl.

Development of an acid hydrolysis method with high recoveries of tryptophan and cysteine for microquantities of protein

High recoveries of tryptophan and cysteine were achieved by 12.5 min of hydrolysis with mercaptoethanesulfonic acid vapor. Proteins (1–100 μg) were modified by vapor-phase S-pyridylethylation before hydrolysis. The modified proteins were hydrolyzed with the vapor of 2.5 m mercaptoethanesulfonic acid at 176°C. This method promoted efficient hydrolysis of the peptide bonds in proteins and resulted in high recoveries of both tryptophan and cysteine, of 90% or greater, in addition to the other amino acids.

Evaluation of hydrophobic SiO2 surfaces prepared by fluorinated organosilane treatments

A surface conversion technique was developed to make the SiO2 surface extremely hydrophobic. Two kinds of fluorine-substituted organosilanes, (heptafluoroisopropoxy)propyl methyl dichlorosilane and trifluoropropylmethyl dichlorosilane, were utilized as the conversion agents. The hydrophobicity was evaluated in terms of the London dispersion force component of the surface free energy (Fowkes's γd s) by measuring the contact angles of CH2I2, hexadecane, and H2O. The values of γd s for the converted surface are 15 and 21 mJ/m2 for the former and the latter conversion reagent, respectively. These surfaces were found to have resistance to 60 min hydrolysis in boiling water and pyrolysis in air up to 450°C.

Development of an enzymatic procedure to produce high-protein amaranth flour

A basic procedure was developed to produce high-protein amaranth flour (HPAF) using a commercial preparation of heat-stable alpha-amylase. Slurries (20%, w/v) of gelatinized whole flour were liquefied at 70 and 90°C, pH 6.5, 0.1% (w/v) enzyme concentration and 30 min hydrolysis time. Protein content of raw flour was increased from 15 to 29.6 or 39.3% at liquefaction temperatures of 70 or 90°C, respectively. Some physicochemical and functional properties of HPAF were assessed. HPAF might be used as a dry milk extender.

Enzymatic Hydrolysis of Amaranth Flour — Differential Scanning Calorimetry and Scanning Electron Microscopy Studies

AbstractHigh‐protein amaranth flour (HPAF) and carbohydrate rich fraction (CRF) were produced from raw flour in a single‐step process using a heat‐stable α‐amylase preparation. Protein content of flour increased from 15 to about 30 or 39% at liquefaction temperatures of 70 or 90°C, respectively, and 30 min hydrolysis time. CRF exhibited 14–22 DE. Enzymatic action at 70°C increased endotherm temperatures and gelatinization enthalpy of HPAF, in relation to gelatinized flour, as assessed by differential scanning calorimetry (DSC). Hydrolysis at 90°C did not affect significantly (P > 0.05) DSC peak temperature. It is suggested that these changes in DSC performance might result from differences in amount and type of low‐molecular weight carbohydrates and residual starch. Scanning electron microscopy (SEM) demonstrated that hydrolysis temperature changed substantially the structural appearance of flour particles. HPAF and CRF might find applications as dry milk extender and sweetener, respectively.

Saccharification of cellulose samples by acid hydrolysis.

Heterogeneous hydrolysis of three cellulose species, Cotton linter (C), NBSP (P) and Regenerated cellulose (R) having a different degree of crystallinity, and homogeneous hydrolysis of P sample were carried out using sulfuric acid. The following results were obtained.The rate of hydrolysis was greater in such a sample with a low crystallinity, and it was in the order of C<P<R sample. When hydrolyzed with 3N H2SO4 at 100°C, _??_, _??_and Polydispersity (PD) initially decreased rapidly and then became constant. The leveling off values of _??_, _??_and PD were about 700, 200, and 3.5, respectively (C, P sample). The corresponding values for R sample were about 50, 40 and 1.2. In case of homogeneous system of P sample after 30min hydrolysis, _??_, _??_and PD were about 140, 80 and 1.8, respectively. _??_and _??_decreased further with hydrolysis time.The yield of sugar was very low in the heterogeneous system, but high in the homogeneous system (attained about 100% at 23°C for 7hr). In case of the homogeneous hydrolysis of P sample (72% H2SO4, 23°C, 7hr), the yields of glucose, cellobiose and cellotriose were 40.1, 16.8 and 10.0%, respectively. Furthermore, when P sample was hydrolyzed with 72% H2SO4 at 23°C for 5hr (primary), diluted to 1% and hydrolyzed again at 60°C for lhr (secondary), the yields of glucose, cellobiose and cellotriose increased to 45.7, 32.7 and 14.1%, respectively.

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Acetaldehyde, the first metabolite of ethanol, reacts with haemoglobin in vitro to produce acetaldehyde-haemoglobin adducts. Some clinical studies on the minor haemoglobins have suggested that these adducts may be formed in people abusing alcohol. Under hydrolysis of haemoglobin, with oxalic acid at 100 degrees C in sealed vials, some acetaldehyde was released and then specifically determined by HPLC. The kinetics of hydrolysis were studied using haemoglobin previously labelled with 14[C] acetaldehyde. The maximum liberation of 14 [C] acetaldehyde was obtained after 3 hr 30 min hydrolysis and this time factor was then utilized in the analysis of alcoholic and control haemoglobin. Thus, we have confirmed the formation of acetaldehyde haemoglobin adducts in vivo. It must be noted that the released acetaldehyde corresponds only to an index of the stable adducts. The levels were higher in alcoholics than in controls (1.417 +/- 0.171 and 1.295 +/- 0.139 nmol/mg Hb, respectively, P less than 0.001). In conclusion, this marker is not a convenient tool for the monitoring of alcohol exposure levels because of the low differences between alcoholic and control haemoglobins.

Treatment variables and amino acid profile of acid-treated straw

Treatment variables such as acid treatment, hydrolysis time, and liquid-to-solid ratio were analysed for straw treated for possible use as animal feed. The acids used were 0·26 n and 0·5 n HCl, 0·5 n H 3PO 4, 0·28 n and 0·5 n H 2SO 4 and a combination of 0·15 n H 3PO 4 and 0·23 n HCl. The fermentability of acid-treated straw measured by the growth of Candida utilis was highest when 0·23 n HCl plus 0·15 n H 3PO 4 were used to hydrolyse the straw. The lowest cell growth occurred with 0·5 n HCl, while the rest of the acid treatments resulted in non-significant differences. The time of hydrolysis (10 or 30 min) and the liquid-to-solid ratios (3/1 or 5/1) had no significant effect on microbial growth. Different acids released different amounts of sugar during hydrolysis. In general, the higher the acidity the higher the sugar yield. There was an interaction between the acid treatment and the liquid-to-solid ratio. Overall, 30 min hydrolysis released more sugar than did hydrolysis for 10 min. In the HCl/H 3PO 4-treated straw the protein was increased two-fold after fermentation. The amino acid profile of the straw fermented with Aureobasidium pullulans was similar to that of alfalfa.

Alcohol fermentation of sweet potato. I. Acid hydrolysis and factors involved

AbstractFactors affecting acid hydrolysis of sweet potato powder (SSP) to fermentable sugars were examined. These include HCl concentration, temperature, time, and levels of SPP. Maximum reducing sugar, reported as dextrose equivalent (DE), was detected after 24 min hydrolysis (1% SPP) in 0.034N HCl heated at 154°C. These samples also had 3.43% droxymethylfurfural (HMF) based on dry weight. A high level of HMF (9.2%) was detected in 1% SPP heated at 154° in 0.10N HCl for 18 min. The lowest concentration of HMF formed (1.8%), at maximal DE of 61%, was established in samples containing 5% SPP and heated at 154° in 0.034N HCl for 48 min. Aqueous extracts of uncured SPP, examined by HPLC, contained glucose, fructose and sucrose, but degraded SPP had only glucose and fructose. Products of degraded SPP, under appropriate conditions, could be used for alcohol fermentation.

Enzyme immunoassay of estriol in pregnancy urine.

We describe an enzyme immunoassay for determination of total estriol in urine. Estriol covalently bound to horseradish peroxidase is used as tracer, and free and bound hormone are separated by precipitation with polyethylene glycol. The method can be used with either acid hydrolysis at 100 degrees C for 30 min or enzyme hydrolysis at 50 degrees C for 40 min; results by the former procedure are about 15% lower than results by the latter. Results were practically identical when we compared the enzyme immunoassay with a radioimmunoassay, using the same antiserum and method of hydrolysis. The day-to-day CV for three different concentrations was 10.7-12.0%, the within-series CV 6.6-8.6%. The additional time required for the enzyme reaction is compensated for by the rapid measurement of light absorbance. Thus this method is faster than radioimmunoassay when more than 25 samples are to be assayed.

Experimental allergic aspermatogenic orchitis IV. Chemical properties of sperm glycoproteins isolated from guinea pig testes

Of four glycoproteins isolated from guinea pig testes, two were aspermatogenic (types I and IV) and two (types II and III) were inactive. The glycoproteins were rich in carbohydrate, varying from 41.5% to 49.5% carbohydrate by weight. Each glycoprotein had a unique amino acid composition, but in general low levels of tyrosine, tryptophan, and basic amino acids were found along with relatively high contents of serine, threonine, glutamic acid, and proline. Types I and IV glycoproteins were remarkably stable; their aspermatogenic activity was not affected by urea, trypsin, or heating at 100 °C in water or in 1 M HCl for 15 min. Carbohydrate analysis revealed little difference in the monosaccharide compositions of types I and IV glycoproteins, except that only the type I contained sialic acid. In contrast, types II and III glycoproteins lacked sialic acid and fucose and contained much less mannose. Both N-acetylglucosamine and N-acetylgalactosamine were present in all four glycoproteins, and they dominated in the types II and III. Fucose and at least 20–25% of the galactose appeared to occupy terminal positions in type IV glycoprotein as shown by their release after 15 min hydrolysis in 1 M HCl. All of the glycoproteins contained a relatively high percentage of galactose by weight, from 12.6 to 19.3%. The molecular weights of the glycoproteins were estimated by sodium dodecyl sulfate gel electrophoresis to be 47 000, 105 000 and 18 000 respectively for the types I, II and IV; type III glycoprotein showed two major bands, with molecular weights of 41 500 and 22 800. All the above molecular weight values are probably overestimated because of high carbohydrate content. The molecular weight of type IV glycoprotein was found to be 13 000 by ultracentrifugation; a corrected value of 29 000 was calculated for type I glycoprotein.

Bitter peptides of casein isolated by hydrolysis with alpha-chymotrypsin and trypsin (author's transl)

Two bitter peptides, H-Phe-Tyr-Pro-Glu-Leu-Phe-OH (I) and H-Val-Glu-Val-Phe-Ala-Pro-Pro-Phe-OH (II) were isolated from casein, hydrolyzed by alpha-chymotrypsin. The hexapeptide is cleaved by thermolysine between Glu and Leu. The two fragments are bitter too. A bitter dodecapeptide (III) was obtained 20 min hydrolysis of casein with trypsin. On account of amino acid composition and N-terminus peptide III is probably identical with a peptide from a 12 hrs hydrolyzate, described in 1970 by Matoba. The peptides I and III have equal taste tresholds in the range of 0.08-0.10 muM/ml.