Showing papers in "Journal of Food Biochemistry in 1981"
TL;DR: Fish muscle lipolysis is presented in the context of basic fish muscle physiology and lipid composition and phospholipase A and lipases from fish muscle have been described and characterized.
Abstract: Lipolysis occurs extensively in fish muscle post-mortem and is associated with quality deterioration in the frozen tissue. Fish muscle lipolysis is presented in the context of basic fish muscle physiology and lipid composition. Phospholipase A and lipases from fish muscle have been described and characterized. The reaction is usually followed by measurement of free fatty acid production, and several colorimetric assays are available. Processing and storage treatments have been shown to influence the extent and rate of lipolysis in fish muscle; most of the research in this area has been directed at the effects of frozen storage. The interaction of lipolysis and lipid oxidation is a particularly intriguing area of study as triglyceride hydrolysis leads to increased oxidation while phospholipid hydrolysis produces the opposite effect.
121 citations
TL;DR: Starch from tubers of Dioscorea alata, Caiaphas cayenensis, Dios corea dumetorum, and Diascorea rotundata was isolated and some of the important characteristics determined by aqueous leaching technique as mentioned in this paper.
Abstract: Starch from tubers of Dioscorea alata, Dioscorea cayenensis, Dioscorea dumetorum, and Dioscorea rotundata was isolated and some of the important characteristics determined. Amylose and amylopectin fractions were obtained by aqueous leaching technique. All the starches appeared to have definite but minor differences in iodine binding capacity, swelling power, solubility, intrinsic viscosity, and amylose/amylopectin ratio. Brabender amylogram of each starch showed no distinct peak viscosity, and the general amylograph pattern was distinctly different from typical amylographs of cereal starches. Amylose fractions from each starch variety exhibited variable degree of β-amylolysis limits ranging from 92–97.5%, and an average molecular weight for amylose triacetate of 210,000 to 265,000. Amylopectin fractions subjected to debranching by pullulanase gave essentially two chain populations of polysaccharides with degree of polymerization of approximately 13–27 and 47–65, respectively. Average unit chain length of the amylopectins ranged from 19 in Dioscorea rotundata to 24 in Dioscorea dumetorum.
70 citations
TL;DR: Arrhenius plots of NAM interaction in solution and in gelation at pH 6.0 indicated two different reaction mechanisms within the temperature zones above and below approximately 35°C for solutions and 40 °C for gels as discussed by the authors.
Abstract: Natural actomyosin (NAM) and “crude” actomyosin formed gels yielding maximum strengths (from back extrusion force) at pH 5.0 and 5.5, respectively. At pH 6.0, NAM gels had a least protein concentration endpoint (LCE) value of 6 mg/ml. Gel strength increased exponentially with an increase of NAM concentration from 3.75–10 mg/ml. With constant time (30 min)-temperature heating, NAM gel forces increased by 20.5% (NS, P>0.05) in the 30–80°C range. Arrhenius plots of NAM interaction in solution and in gelation at pH 6.0 indicated two different reaction mechanisms within the temperature zones above and below approximately 35°C for solutions and 40°C for gels. Similarity of interaction slopes above the 35–40°C region suggested one reaction mechanism for NAM molecular aggregation in solution and gelation.
59 citations
TL;DR: α-Amylase inhibitor is presented in maize seeds and was active against α-amylase of maize, produced during germination as well as against Bacillus subtilis α- amylase, but it was inactive against α,amyl enzyme from human saliva, hog pancreas, Aspergillus oryzae, wheat, rye, barley, triticale and sorghum.
Abstract: α-Amylase inhibitor is presented in maize seeds. It is a protein as indicated by precipitation with ammonium sulfate and trichloroacetic acid, denaturation by heat, digestion with proteases and by dye-staining.
It was purified to homogeneity by ammonium sulfate precipitation and Sephadex G-75 gel filtration. It had an apparent molecular weight of 29,600 and did not contain any carbohydrate.
Its properties differed from those of previously reported α-amylase inhibitors, since it was active against α-amylase of maize, produced during germination as well as against Bacillus subtilis α-amylase.
It was also active against α-amylase from the insects Tribolium castaneum, Sitophilus zeamais and Rhyzopertha dominica, but it was inactive against α-amylase from human saliva, hog pancreas, Aspergillus oryzae, wheat, rye, barley, triticale, and sorghum.
It was stable for 5 min at 96°C at pH 7. Maximal inhibition required at least 10 min of preincubation with the enzyme at pH 6.8 and 257deg;C. Polyacrylamide gel electrophoresis gave three protein bands, but only one was obtained in S.D.S. and mercaptoethanol.
57 citations
TL;DR: The aformentioned results were interpreted as indicating the previous presence of phosphorylase in the preclimacteric phase without new synthesis during ripening, probably due to ribosomal synthesis rather than to nucleic acid synthesis.
Abstract: Starch levels as well as the phosphorylases and acid phosphatase activity during ripening of the banana fruit was investigated The concentrations and sequence of appearance of sucrose, glucose and fructose were determined by use of specific enzymatic reactions During the climacteric period, the phosphatase activity increased while phosphorylase activity, which initially increased before starch transformation began, thereafter decreased in a complex pattern The starch was transformed into sucrose with later formation of glucose and fructose Four bands of phosphorylase multiple forms, detected electrophoretically, did not change during ripening One of them was able to synthesize a branched starch-using amylose as a primer and glucose 1 -phosphate as the substrate Banana slices were infiltrated with water or solutions of cycloheximide or actinomycin D Inhibition of phosphatase-induced activity was recorded only in the cycloheximide group No change in phosphorylase activity was detected in any of these infiltrated groups Sucrose production from starch was partially inhibited both by actinomycin D and cycloheximide The aformentioned results were interpreted as indicating the previous presence of phosphorylase in the preclimacteric phase without new synthesis during ripening The increase of activity of phosphatase was probably due to ribosomal synthesis rather than to nucleic acid synthesis
50 citations
TL;DR: In this article, a model of microcrystalline cellulose, sucrose, and invertase was selected to study the behavior of invertases as functions of water activities, time and temperature.
Abstract: Enzyme-catalyzed reactions occur at a wide range of moisture levels, including those corresponding to water activities (aw) well below unity. The model system of microcrystalline cellulose, sucrose and invertase was selected to study the behavior of invertase as functions of aw, time and temperature.
The results show that the Onset of reaction occurs below the anticipated mobilization for crystalline sucrose (aw 0.81) and that measurable reaction occurs at an aw as low as 0.58. The Maximum Extent of reaction is independent of moisture content at or above aw 0.75. The overall Rate of reaction for a given treatment fitted a first-order kinetic model. Rate constants (a) obeyed Arrhenius plots (25° to 47°C) with activation energies (Ea) varying from 15.7 to 4.8 Kcal/mole for aw's from 0.58 to 0.90, respectively, (b) increased in direct proportion to enzyme concentration, and (c) increased strongly and nonlinearly with aw and moisture.
A model with two rate-limiting steps has been postulated. At high moisture content, sucrose diffusion through a resistance shell confined to the vicinity of an invertase molecule is limiting. At low moisture content, aw and temperature may affect the conformation of the enzyme itself, or the diffusion coefficient in the rate-controlling resistance shell.
43 citations
TL;DR: It is demonstrated how enzymes produced and elaborated by human colon bacteria can markedly alter the physical properties of a dietary component which reaches the colon.
Abstract: A strain of Bacteroides ovatus from the human colon was grown on guar gum, a highly-branched galactomannan which is widely used as a food additive.
Growth on guar gum induced production o f extracellular enzymes which partially degraded and/or deaggregated guar gum. The enzymes rapidly reduced the viscosity of guar gum solutions, while breaking only a limited number of glycosidic bonds. The molecular weight (versus dextran standards) of the guar gum decreased sharply as the viscosity decreased. No mono-, di- or trisaccharides were produced during enzyme action, although small quantities of higher oligomers were present after longer (5–8 h) incubations. The enzyme had a sharp temperature optimum at 37°C for an incubation time of 60 min, but was stable for only a few hours at this temperature.
These results demonstrate how enzymes produced and elaborated by human colon bacteria can markedly alter the physical properties of a dietary component which reaches the colon. Further studies of both substrate and enzymes will be required to establish the mechanism of this alteration and to establish how B. ovatus is able to utilize guar gum for growth.
32 citations
TL;DR: Three trypsin-chymotrypsin inhibitors were purified to homogeneity from Phaseolus vulgaris L. var Rosinha G2 (Brazilian pink beans) and were very similar, although distinguishable, by amino acid analysis.
Abstract: Three trypsin-chymotrypsin inhibitors were purified to homogeneity from Phaseolus vulgaris L. var Rosinha G2 (Brazilian pink beans). At least one more trypsin-chymotrypsin inhibitor was present. Purfication was achieved by fractionation into albumin and globulin fractions based on differential salt/water solubilities, affinity chromatography on trypsin-Sepharose, DEAE-cellulose chromatography and CM-cellulose chromatography. Purity of the inhibitors was determined by rechromatography, combining ratios with trypsin and by disc gel electrophoresis. The isolated inhibitors were very similar, although distinguishable, by amino acid analysis. They had no tryptophan and valine, one residue of methionine, low glycine, alanine, leucine and tyrosine contents and high levels of serine, threonine, proline and half-cystine (18.5 to 21.0 residues per molecular weight of 20,000). They also contained a low amount of carbohydrate (one equivalent of mannose per 20,000 g protein).
16 citations
TL;DR: It was found to be associated with the plasmalemma (plasma membrane) in the majority of embryonic cells which is contrary to the general belief that myrosinase is found only in a few specialized idioblasts called ‘myrosin cells’.
Abstract: Myrosinase (thioglucoside glucohydrolase, EC 3.2.3.1) activity in dehulled seeds of Brassica napus cultivar Tower, B. campestris cultivar Candle and B. juncea (oriental mustard) was localized by cyto-chemical and biochemical procedures. It was found to be associated with the plasmalemma (plasma membrane) in the majority of embryonic cells which is contrary to the general belief that myrosinase is found only in a few specialized idioblasts called ‘myrosin cells’. The presence of lead and sulfur in electron-opaque deposits resulting from in situ myrosinase activity was confirmed by energy dispersive X-ray analyses. Association of myrosinase activity with the plasmalemma was also verified by fractionation and biochemical procedures. Although there were indications of some myrosinase activity in aleurone grains (protein bodies), the evidence was inconclusive.
16 citations
TL;DR: The haemagglutining material isolated by affinity chromatography (CII-Af) contained at least three active protein bands as shown by polyacrylamide gel electrophoresis, and the CII-β component gave a single active band in the pH range of 5.5–5.7.
Abstract: A purified lectin was prepared from 0.15 M NaCl extracts of bean (Phaseolus vulgaris var. Rosinha G2) by affinity chromatography on ConA-Sepharose followed by gel chromatography on Sephadex G-200.
The haemagglutining material isolated by affinity chromatography (CII-Af) contained at least three active protein bands as shown by polyacrylamide gel electrophoresis. By chromatography on a Sephadex G-200 column, the (CII-Af) fraction gave only a major peak (CII-β) with haemagglutininating activity, which showed a single broad band on gel electrophoresis. Gel isoelectric focusing of the CII-β component gave a single active band in the pH range of 5.5–5.7. The purified lectin was a glycoprotein, containing 8.30% of neutral sugars (as mannose) and 2.12% of hexosamine (as glucosamine) and only trace amounts of sulphur-containing amino acids. The protein had a MW of 136,000 (6.9 S) with a Stokes radius of 43 A, a calculated diffusion constant (D20,w) of 5 times 10−7 cm2 s−1, and a partial specific volume (v) of 0.75 ml.g−1. From its frictional ratio f/fo = 1.3 and assuming a hydration capacity of 0.3 to 0.4 g of water/g of protein, the axial ratio for the lectin molecule would be in the range of 3–4 if a prolate ellipsoid of revolution is chosen as a model.
14 citations
TL;DR: The influence of gamma irradiation at a radurizing dose of 1.5 kGy on the proteins of Indian mackerel was examined and resulted in enhancement in tryptic digestibility of sarcoplasmic proteins and ATPase activity of myosin.
Abstract: The influence of gamma irradiation at a radurizing dose of 1.5 kGy on the proteins of Indian mackerel (Rastrelliger kanagurta) was examined. The fish proteins were comparatively stable towards changes by the treatment, as ascertained by several parameters. However, irradiation at 1.5 kGy resulted in enhancement in tryptic digestibility of sarcoplasmic proteins and ATPase activity of myosin.
TL;DR: Acyl CoA:sn-glycero-3-phosphate O-acyltransferase catalyzes the first committed step in the biosynthesis of phospholipids and acylglycerols in soybeans indicating that a sulphydryl group is essential for activity.
Abstract: Acyl CoA:sn-glycero-3-phosphate O-acyltransferase (glycerophosphate acyltransferase, EC 2.3.1.15) catalyzes the acylation of glycero-3-phosphate to form lysophosphatidic acid. This enzyme catalyzes the first committed step in the biosynthesis of phospholipids and acylglycerols in soybeans. Glycerophosphate acyltransferase was predominatly associated with the microsomal fraction of germinating soybeans. The pH optimum for the reaction was 7.0. The enzyme exhibited saturation kinetics for glycero-3-phosphate (Km of 0.2 mM) and palmitoyl CoA (Km of 6.4 μM). A variety of acyl CoA derivatives served as substrates for the enzyme. Palmitoyl CoA was the most effective acyl CoA substrate. The addition of the nonionic detergent Triton X-100 inhibited glycerophosphate acyltransferase activity. Thioreactive agents inhibited the enzyme indicating that a sulphydryl group is essential for activity. The activation energy for the reaction was 8.8 Kcal per mole. The microsomal enzyme was reasonably stable to temperatures up to 70° C.
TL;DR: The pectic substances in two samples of New Zealand grapefruit juice were determined by a spectrophotometric method after fractional extraction of the alcohol-insoluble solids.
Abstract: The pectic substances in two samples of New Zealand grapefruit juice were determined by a spectrophotometric method after fractional extraction of the alcohol-insoluble solids. No significant difference in anhydrogalacturonic acid (AGA) content was found when the chromogen was formed using m-hydroxydiphenyl and carbazole.
In the analysis of the pectic substances in red and white grape berries, chromogen formation with carbazole gave AGA contents of the water-soluble fraction of the alcohol-insoluble solids five to seven times greater than when the chromogen was formed using m-hydroxydiphenyl. It is suggested that phenolic material in the grape extracts reacted with the carbazole to give the higher apparent AGA contents.
TL;DR: In this paper, the authors extract soybean meal with 40% ethanol in water and a short autoclaving, which yields a residue which supports a growth rate 27% greater than that of conventionally autoclaved meal when fed to weanling male rats.
Abstract: Extraction of raw soybean meal with 40% ethanol in water and a short autoclaving yields a residue which supports a growth rate 27% greater than that of conventionally autoclaved meal when fed to weanling male rats. This residue contains an average of 73% of the dry matter and 91% of the protein of the original raw meal.
TL;DR: The three trypsin inhibitors previously isolated from Brazilian pink bean had molecular weights of 18,200 to 18,500 by sodium dodecyl sulfate polyacrylamide gel electrophoresis, 20,000 by gel filtration on Sephadex G-100 and 20,400 by sucrose density gradient ultracentrifugation with a Stokes molecular radius of 20 A, indicating that the inhibitors have lysine in binding site fortrypsin.
Abstract: The three trypsin inhibitors A, B and C previously isolated from Brazilian pink bean (Phaseolus vulgaris L. var. Rosinha G2) had molecular weights of 18,200 to 18,500 by sodium dodecyl sulfate polyacrylamide gel electrophoresis, 20,000 by gel filtration on Sephadex G-100 and 20,400 by sucrose density gradient ultracentrifugation with a Stokes molecular radius of 20 A, a frictional coefficient of 1.14, a diffusion coefficient of 10.7 × 10−7 cm2s−1, a partial specific volume of 0.69 cm3g−1 and a molar absorptivity of 5.5 × 103 M−1 cm−1 at 280 nm. All three inhibitors bound two moles of trypsin and one mole of chymotrypsin. The Ki values for trypsin were: A, 8.5 × 10−10 M; B, 1.8 × 10−10 M and C, 6.8 × 10−10 M while for chymotrypsin they were: A, 4.4 × 10−7 M; B, 2.8 × 10−8 M and C, 3.0 × 10−8 M. Reductive methylation caused loss of inhibitor activity of all three inhibitors against trypsin without significantly affecting inhibitor activity against chymotrypsin (with exception of inhibitor B), indicating that the inhibitors have lysine in binding site for trypsin. Partial reduction of the disulfide bonds caused loss of inhibitor activity against both trypsin and chymotrypsin with some regain of inhibitor activity following dialysis. Cyanogen bromide cleaved all three inhibitors into two fragments with significant retention of inhibitor activity. Cyanogen bromide-treated inhibitor B had nearly twice the original inhibitor activity against trypsin with no loss of inhibitor activity against chymotrypsin.
TL;DR: The crude extract of Antarctic krill Euphausia superba contained high activities of galactomannoglycanase, carboxymethyl cellulase, chitinase, amylase and relatively low activities of agarase, mannanase, kappa-carrageenanase and pectinase.
Abstract: The crude extract of Antarctic krill Euphausia superba contained high activities of galactomannoglycanase, carboxymethyl cellulase, chitinase, amylase and relatively low activities of agarase, mannanase, kappa-carrageenanase and pectinase. The extract also showed high activities of β-D-fucosidase, β-D-glucosidase, β-D-galactosidase and relatively low activities of α-D-glucosidase, α-D-mannosidase, α-D-galactosidase, α-D-fucosidase and β-D-galacturonidase. The sufficiently high activities of carboxymethyl cellulase, galactomanno-glycanase, chitinase, β-D-fucosidase, β-D-glucosidase and β-D-galactosidase make krill a potential source for futher studies on the properties and utilization of these enzymes.
TL;DR: In this paper, the effect of substituting the chick peas in Faffa with haricot beans was examined and the protein efficiency ratio (PER) was drastically reduced due to the substitution.
Abstract: Faffa, the commercially produced infant formula in Ethiopia, contains approximately 20% protein derived from wheat, soy flour, chick peas and skimmilk. The paper examines the effect of substituting the chick peas in Faffa with haricot beans. Protein efficiency ratio (PER) was drastically reduced due to the substitution. Pre-toasting the haricot beans improved the PER value of the Faffa to the level of that of chick peas Faffa.
The essential amino acid patterns of the two preparations of Faffa were found to be similar and therefore could not explain the difference in PER. It was suspected that improvement of PER by heat treatment of the haricot bean Faffa was due to inactivation of the trypsin inhibitor. Analysis for trypsin inhibitor content confirmed that the lower PER value for Faffa prepared from untoasted Faffa is due to higher trypsin inhibitor content of haricot beans as compared to chick peas.
TL;DR: In this article, the authors applied methyl esters to the surface of apples and when the lipids were extracted from the fruit after four weeks of cool storage, they found that, while each methyl ester was metabolised to some extent to non-lipid compounds, there was minimal incorporation of applied methyl enters into other lipid fractions such as glycerides or phosopholipids.
Abstract: Methyl esters were applied to the surface of apples and when the lipids were extracted from the fruit after four weeks of cool storage it was found that, while each methyl ester was metabolised to some extent to non-lipid compounds, there was minimal incorporation of applied methyl ester into other lipid fractions such as glycerides or phosopholipids. Methyl esters also enhanced the metabolism of [14C]—fatty acids to nonlipid compounds. Methyl stearate and lecithin reduced the rate of ethylene production while methyl linoleate and methyl oleate had no significant effect but no compound significantly changed the rate of respiration. The principal action of methyl esters and other lipids in reducing soft scald is considered not to be due to their effect on lipid composition but rather on the amount of hexanol in the fruit.
TL;DR: The interaction of malonaldehyde with lysozyme has been assessed with reference to incubation time, pH, concentration and aging, and a small proportion of compounds absorbing at 267 and 350 nm was revealed.
Abstract: The interaction of malonaldehyde with lysozyme has been assessed with reference to incubation time, pH, concentration and aging. Gel filtration studies revealed that freshly prepared malonaldehyde contains a small proportion of compounds absorbing at 267 and 350 nm, which shows significant increase upon incubation of malonaldehyde. While higher concentration of malonaldehyde leads to inactivation of enzyme, lower concentration (2.5 mM) stimulates the lytic function of lysozyme. Stimulation and inactivation of the enzyme have been discussed in the context of degradation of malonaldehyde.
TL;DR: Increases in TPP content were noted during ripening of avocado and pear fruit however, the significance of the increases was circumscribed by limitations inherent to the extraction and assay procedures.
Abstract: A method for the measurement of thiamine pyrophosphate was reexamined with regard to optima for pH, temperature, incubation time, and pyruvate decarboxylase apo-enzyme concentration. The purified apo-enzyme was shown to be stable for 30 days at -80°C. Optimized conditions resulted in assays about 10 times faster than previously described. Increases in TPP content were noted during ripening of avocado and pear fruit however, the significance of the increases was circumscribed by limitations inherent to the extraction and assay procedures. Regulatory functions of TPP and their potential role in fruit tissues are discussed.
TL;DR: In this article, the effects of solvent extraction and drying on neutral detergent fiber (NDF) values of foods of high sugar content were evaluated and it was found that Soxhlet extraction with a 1:l mixture of acetone and petroleum ether resulted in 117% higher NDF value for raisins than was observed for the untreated sample.
Abstract: The effects of solvent extraction and drying on neutral detergent fiber (NDF) values of foods of high sugar content were evaluated. It was found that Soxhlet extraction with a 1:l mixture of acetone and petroleum ether resulted in 117% higher NDF value for raisins than was observed for the untreated sample. This solvent mixture extracted approximately 5wo as much lipid material as did diethyl ether. The addition of sugar as glucose or sucrose and cooking at low boil for five minutes did not affect the NDF value of whole wheat flour. However, cooking caused the 1:l acetone petroleum ether extractables to be decreased. Soxhlet extraction and subsequent drying did not affect the NDF values of spinach, parsnips, cherries, or raspberries. The conservative use of heat as in Soxhlet extraction and subsequent drying did not consistently affect NDF values of the foods studied.
TL;DR: Initial adjustment of pH of growth medium in the range of 3.0–5.0 was found to be necessary for optimal production of glucoamylase by a newly isolated strain of Aspergillus niger, which led to faster fungal growth rate and increased biomass.
Abstract: Initial adjustment of pH of growth medium in the range of 3.0–5.0 was found to be necessary for optimal production of glucoamylase by a newly isolated strain of Aspergillus niger. Optimum temperature of incubation under stationary conditions was found to be 26–28° C, although incubation at higher temperatures viz. 30 and 37° C led to faster fungal growth rate and increased biomass. In complex medium, the optimum glucose and peptone concentrations were 2 and 3% respectively, and the presence of trace elements was found to be essential for maximal enzyme yield.