Quantitative Determination of Carrageenan in Milk and Milk Products Using Papain and Cetyl Pyridinium Chloride

SUMMARY– Proteins in milk, chocolate milk, evaporated milk, and ice cream containing added carrageenan were digested with papain at 70°C in the presence of 1.0 M NaCl. The digest was adjusted to pH 8.0 to 8.5 with NaOH. Celite was added and the mixture filtered over glass wool. Carrageenan in the filtrate was precipitated with cetyl pyridinium chloride (C.P.C.) in the presence of 0.5 to 1.0 M KCl and Celite. The carrageenan-C.P. precipitate was washed with 0.1% C.P.C.-0.05 M KCI until the filtrate was negative to the Benedict's test. Then, it was dissolved in 30% H₂SO₄ and the carbohydrate content determined by the phenol-H₂SO₄ method.
At concentrations of 0.01 to 0.2% carrageenan, average recoveries of 92 to 102% were obtained from milk. For chocolate milk, evaporated milk and ice cream, and at a level of 0.1% carrageenan, recoveries of 90, 94 and 96%, respectively, were obtained. Optimum conditions for the isolation of the carrageenan cetyl pyridinium complex were established.     

RESEARCH NOTE THE EFFECTS OF SALTS ON THERMAL TRANSITION CURVES OF COD MUSCLE

Examination of the thermograms of cod muscle to which various salts have been added indicate that NaI decreases transition energies of both myosin and actin as compared to a no salt control, and to NaCl and Na₂SO₄ treated samples. In contrast, CaCl₂ and MgCl₂ increases but broadens the peaks.     

Solubility of amaranth seed proteins in sodium sulphate and sodium chloride: the main factor in quantitative extraction for analysis

Nitrogen was extracted more efficiently from amaranth seed with 0.04 M Na₂SO₄ (5% w/v) than with either 0.09 M or 0.17 M NaCl (5% or 10% w/v), despite both solutions having the same ionic strength (μ= 1). Solubility of saline soluble proteins (albumin ± globulin) was very poor in either water or 1M NaCl, but increased in 0.4M NaCl at alkaline pH between 7 and 10. Globulins were very soluble in 0.4M NaCl at a pH 9. Albumin was the main storage protein. Saline soluble proteins formed very weak gels.     

Isolation of Tomato Seed Meal Proteins with Salt Solutions

Salt solutions were used in isolating tomato seed meal proteins. Na₂SO₃ and NaCl solutions at different concentrations, and pH were included in a central composite design to find optimum conditions of protein isolation. The highest total protein yield was achieved with water extraction (no salt present). Salt extraction at pH 7.5 produced isolates with protein content of 93.4% (NaCl 5% w/v) and 77.1% (Na₂SO₃ 0.5% w/v). Observed values were in good agreement with predicted values. Isolates extracted with different salt solutions ranged from less soluble but very resistant to heat and Ca²⁺, to very surface active with functional properties comparable to commercial soy isolates.     

Efficacy of Sulfuric Acid Scarification and Disinfectant Treatments in Eliminating Escherichia coli O157: H7 from Alfalfa Seeds Prior to Sprouting

ABSTRACT: E. coli O157:H7 reduction on inoculated alfalfa seeds was investigated using acid scarification treatments with or without subsequent application of sanitizers. Scarification with 0.1 to 2N H₂SO₄ for 2.5 to 45 min did not affect (p ≤ 0.05) seed viability. E. coli O157:H7 was reduced by 2.1 to 5.0 logs after treating with 0.1 to 2N H₂SO₄ for 5 to 20 min. Combined scarification (0.5N H₂SO₄) and H₂O₂ or CH₃COOH treatments enhanced microbial destruction by less than 1 log compared to sanitizer alone. Chlorine, Na₂CO₃, or Na₃PO₄ treatments preceded by scarification did not significantly increase microbial destruction compared to sanitizer alone. Appreciable reductions in seed germination were only observed with chlorine treatments.     

Optimization of Medium Composition for Cultivating Clostridium butyricum with Response Surface Methodology

ABSTRACT: Probiotic bacteria, such as some strains of Clostridium butyricum , have been frequently used as the active ingredient in functional foods. However, slow growth of the probiotic bacteria has been one of the big concerns for their potential commercial application. In the present study, a fractional factorial design was applied to investigate the main factors, namely, the concentrations of the glucose, tryptone, yeast extract, beef extract, cys-teine, (NH₄) ₂SO₄, NaCl, K₂HPO₄, and the medium initial pH that affected the growth of 1 probiotic strain, C. butyricum ZJUCB, currently preserved in our laboratory. Central composite experimental design and response surface methodology were adopted to derive a statistical model for optimizing the composition of the medium. The experimental results showed that the optimum medium for incubating the C. butyricum ZJUCB was composed of 2.44% (w/v) glucose, 2.08% yeast extract (w/v), 1% tryptone (w/v), 0.1% (NH₄)₂SO₄ (w/v), 0.1% NaHCO₃ (w/v), 0.02% MnSO₄. H₂O (w/v), 0.02% MgSO₄. 7H₂O (w/v), 0.002% CaCl₂ (w/v), and 2% agar (w/v) (if necessary) at pH 8.55. After incubation for 24 h in the optimum medium, the populations of the viable organisms could reach 10⁹ colony-forming units (CFU)/mL, which was 100 times higher than that incubated in the initial medium.     

PURIFICATION AND CHARACTERIZATION OF POLYPHENOL OXIDASE FROM POTATO: II. INHIBITION AND CATALYTIC MECHANISM

KCN and ascorbic acid showed competitive inhibition patterns with K_is values of 0.032 and 0.27 mM, respectively. Uncompetitive inhibition patterns were obtained with sodium azide, L-cysteine and NaCl with K_ii values of 3.3 mM, 0.12 mM and 0.3 M, respectively. A noncompetitive inhibition pattern was obtained for thiourea with 0.067 mM for K_is and 0.59 mM for K_ii. Cu₂⁺ increased the activity about 2.5 fold at or above 40 μM and K⁺ decreased the enzyme activity about 33% at 0.4 M. Other metal ions did not have any effects on the activity. Two pK values of 5.8 and 8.0 were obtained from V_max profile and two pK values of 5.9 and 8.1 from V_max/K_m profile. The data suggest that cysteine is likely to be involved in catalysis and histidine in binding. Data from chemical modification show that cysteine was completely inactivated at 1.74 mM o-methylisourea, and histidine and tryptophan were modified at much higher concentrations of diethylpyrocarbonate and N-bromosuccinimide, respectively. It is suggested that the protonated cysteine works as a general base, tryptophan as a substrate binding residue and histidine as a oxygen binding residue.     

Structure and Composition of Mushrooms as Affected by Hydrogen Peroxide Wash

An experimental H₂O₂/browning inhibitor wash treatment and its effect on mushroom structure and composition were studied. Experimentally washed mushrooms ( Agaricus bisporus ) were compared with conventionally washed mushrooms and untreated controls. Examination by scanning electron microscopy showed damage to hyphae producing a matted appearance at the pileus surface with both experimental and conventional washed samples. Mushrooms after the experimental wash had an elevated sodium content from the sodium erythorbate browning inhibitor but contained no H₂O₂ residue. In pileus tissue, soluble phenol levels were higher and the content of free amino acids was lower in mushrooms after the experimental wash. No other notable compositional differences or adverse effects of treatment on quality were found.     

THE EFFECT OF pH, POLYPHOSPHATES AND DIFFERENT SALTS ON WATER RETENTION PROPERTIES OF GROUND TROUT MUSCLE

The water binding potential (WBP) and expressible moisture (EM) curves of ground rainbow trout white muscle versus pH are different, particularly in the region from pH 5.0 to 7.0. The effect of different salts such as CaCl₂, Mg Cl₂, NaCl, Nal and Na₂SO₄ on WBP suggests that for the same salts, cations cause a smaller change than anions. On the other hand, the EM measurements suggest that cations have a greater effect on this measurement than anions. In the case of WBP, the effect of tripolyphosphate and pyrophosphate can be attributed solely to their effect on pH. These results indicate the differences between the two methods and suggest that they measure different components of the water retention properties of a complex system, and thus water holding capacity measurements must be interpreted with care.     

Shelf-Life Extension of Fresh Mushrooms (Agaricus bisporus) By Application of Hydrogen Peroxide and Browning Inhibitors

ABSTRACT: An experimental washing process for fresh mushrooms entailing immersion in 5% H₂O₂, followed by application of a sodium erythorbate-based browning inhibitor, was optimized, scaled up, and made continuous. The laboratory process described previously was modified by adding a pre-wash step using 0.5% to 1% H₂O₂, increasing the wash solution H₂O₂ concentration from 3% to 5%, and substituting 4% sodium erythorbate + 0.1% NaCl for the more complex browning inhibitor formulation used previously. A continuous, commercial-scale washing facility was built to test the new process. Mushrooms washed by this process were free of adhering soil, less subject to brown blotch than conventionally washed mushrooms, and at least as resistant to enzymatic browning as unwashed mushrooms during storage at 4 °C. Storage at 10 °C accelerated development of brown blotch and browning.     

Comparison of six methylation methods for analysis of the fatty acid composition of albacore lipid

Six methods widely used to produce methyl esters for the gas chromatographic determination of the fatty acid composition of a marine lipid were compared. Four acid-catalyzed methods (1% H₂SO₄: CH₃OH; 5% HCl: CH₃OH; 7% and 14% BF₃: CH₃OH) and two base-catalyzed methods [0.5M NaOCH₃: CH₃OH; (1:4) tetramethylguanidine: CH₃OH] were used.
The use of BF₃: CH₃OH (7% and 14%) gave a lower content of 18:1 n9 than the other methods and produced an artefact (2.7–3.2% of total fatty acid content) eluting between the 20:5 and 24:1 fatty acid methyl esters. No significant differences were obtained between the other four methods.
Accordingly the use of BF₃: CH₃OH for transmethylation of marine lipids is not recommended. Results obtained in the other four methods showed that all are comparable.     

EFFECT OF SLURRY PREPARATION METHODS ON THE RHEOLOGICAL AND GELLING BEHAVIOR OF SOY PROTEIN

The order of addition of solutes and soy protein during the preparation of slurries influenced rheological behavior of unheated and heated slurries. The effect of the order of addition of glucose, sucrose and Na₂HPO₄ into the slurries was small with respect to the influence of the order of addition of CaCl₂ and NaCl. The effectiveness of salts in reducing apparent viscosity of both unheated and heated slurries was greater than that of glucose and sucrose. Na₂HPO₄ was the more effective salt in reducing viscosity followed by NaCl and CaCl₂. When salts were added, an inverse relationship was obtained between viscosity and water-holding capacity of gelled soy protein slurries.     

INACTIVATION AND REGENERATION OF IMMOBILIZED CATALASE

Catalase was immobilized on collagen membrane. The inactivation of immobilized catalase by 0.01M and 0.1M H₂O₂ was reported. After the initial stage of inactivation, a stable catalatic activity as measured in a continuous flow of 0.01M H₂O₂ through a modular reactor was observed for longer than 20 days (2.6 min residence time). The regeneration of catalatic activity from the O.1M H₂O₂ inactivated catalase occurred after incubating the inactivated modular reactor with 0.01M phosphate buffer, pH 6.8. The amount of activity regenerated is directly proportional to the time of incubation.     

POTENTIAL FOR EXAGGERATION OF PCB CONTENTS OF PACKAGED FISH BY PHTHALATES FROM THE WRAPPING MATERIAL OR SOLVENTS

A convenient method for recovering PCBsfrom lipids is to digest the matrix in concentrated H₂SO₄ and recover the unaffected PCBs into hexane for determination by gas chromatography with electron capture detection. In a recent fish analysis case the peaks for these PCBs were accompanied by a large component identified as di- (2-ethylhexyl) phthalate, shown to have migrated into fish lipidfrom a heavy plastic wrap, and only partly destroyed by the H₂SO₄. The di-n-butyl and di-(2-ethylhexyl) phthalates bracket the major Aroclor peak region of chromatograms on a methyl silicone GC column and possibly a di-n-hexyl phthalate ester would very likely be superimposed directly on the PCBs. In the course of this work it was found that commercially available hexanes of presumed high quality contained the same di-(2-ethylhexyl) phthalate plasticizer in proportions high enough to be of concern in such analyses.     

The preparation of protein hydrolysate from defatted coconut and soybean meals

This study was conducted to determine the effects of temperature, time and concentration of acids on the hydrolysis of coconut and soybean meals. Using 6∼ hydrochloric acid (HCl), the complete hydrolysis of soybean meal was reached after 36 hr at 95°C, while it took only 24 hr to complete the process when 18 N sulphuric acid (H₂SO₂) was used at the same temperature. Coconut protein exhibited some degree of resistance to hydrolysis. Using 10 N HC1 and 18 N H₂SO₂ in two separate tests, it took 48 hr to complete hydrolysis at 95°C. Sulphuric acid caused a considerably greater decomposition of amino acids than HCl during longer periods of reaction with high acid concentration and temperature. Flavour development is a function of the free amino acids released which in turn is a function of acid concentration, reaction time and temperature.     

Effect of different extraction and precipitation methods on yield and quality of pectin

An experimental study has been conducted to determine the combined effects of different extraction conditions and precipitation method on the yield and quality of high methoxyl pectin from lemon peels. Pectin was extracted using different mineral acids (HCl, HNO₃ and H₂SO₄) at four concentration levels (0.025; 0.05; 0.1 and 0.2  m ), at 70 °C for 4 h. The soluble pectin was precipitated by iso-propanol or by an aluminium sulphate, Al₂(SO₄)₃, solution at pH 4. The extraction with HCl and HNO₃, at the highest concentrations investigated, followed by aluminium precipitation led to the best results in terms of yield (22–25%), quality and gelling power of pectin with a remarkable decrease of alcohol consumption as compared to the alcoholic precipitation under the same extracting conditions.     

Influence of sodium chloride and glucose on the aggregation behavior of heat-denatured ovalbumin investigated with a multiangle laser light scattering technique

ABSTRACT:  The molecular characteristics of ovalbumin aggregates formed by heating with NaCl and glucose were investigated with a multi-angle laser light scattering system. The presence of NaCl and glucose affected the formation and molecular structure of the aggregates. Specifically, glucose increased the denaturation temperature of ovalbumin due to thermal stabilization of the native state of ovalbumin, regardless of the content of added NaCl. The surface hydrophobicity of the aggregates was increased by the addition of NaCl, which induced the denaturation of ovalbumin at a lower temperature. Aggregates with a larger weight-average molar mass ( M_w ) and root mean square radius ( R_g ) formed from heat-denatured ovalbumin with NaCl and glucose. The presence of NaCl during heat denaturation caused the formation of aggregates with a larger M_w (1.9 × 10⁵ and 3.5 × 10⁶ g/mol for 0 and 10 mM NaCl, respectively) and R_g (14.8 and 80.4 nm for 0 and 10 mM NaCl, respectively). Over a certain amount of NaCl, the addition of more glucose resulted in the formation of more aggregates with greater M_w and R_g values. In sum, the thermostability of ovalbumin was affected primarily by glucose, but the molecular characteristics of the soluble aggregates formed by heat denaturation varied primarily with NaCl content.     

The rheological properties of ketchup as a function of different hydrocolloids and temperature

The flow properties of ketchup were assessed upon addition of commonly used food thickeners: guar, xanthan and CMC gum at three different concentrations (0.5%, 0.75% and 1%) and four temperatures (25, 35, 45 and 55 °C). The ketchup without supplementation served as a control. All ketchup formulations exhibited non-Newtonian, pseudoplastic behaviour at all temperatures and hydrocolloid levels. The Power-law and Herschel-Buckley model were successfully applied to fit the shear stress versus shear rate data. The flow behaviour indices, n and n' , varied in the range of 0.189–0.228 and 0.216–0.263, respectively. The consistency coefficients, k and k' , were in the range of 8.42–27.22 and 6.56–20.10 Pa s ⁿ , respectively. The addition of hydrocolloids increased the yield point (τ₀) and apparent viscosity of the ketchup in comparison to that of the control. The Arrhenius equation was successfully used to describe the effects of temperature on the apparent viscosity of the prepared formulations. The E _a value appeared in the range between 5492.6 and 21475.8 J mol⁻¹.     

CARBOISIYL AND FATTY ACID ANALYSIS OF ANTELOPE AND BEEF FAT

Characterization of kidney fat from twelve antelope and four beef was accomplished by monocarbonyl, ketoglyceride and fatty acid analysis. Antelope lipids are highly saturated, possessing strong odor and flavor characteristics which many people find objectionable. The antelope fat had a stearic acid content of 42% and an oleic acid content of only 20% while beef fat contained 28% stearic and 34% oleic acid. The lipid was further analyzed by reacting on a 2, 4-DNPH Celite impregnated column. The derivatives were separated from unreacted lip-id, and monocarbonyls and ketoglycerides fractionated using column chromatography. The ratio of monocarbonyls to ketoglycerides was about 1:3 in beef and 1:1 in antelope. Amounts of monocarbonyls average 0.70 μM/g of fat for beef and 1.47 μM/g of fat for antelope. Further analysis of the monocarbonyls indicated 7% methyl ketones, 70% saturated aldehydes, 18% enals and 6% 2,4 dienals in beef while antelope had 15%, 70%, 11% and 4%, respectively. Major constituents of the saturated aldehydes were C₂ through C₈ for both species and C₁₀ for beef while the major methyl ketones were C₃ through C₇ for both species. Methyl ketone, saturated aldehyde and enal fractions showed similar trends in composition with short-chain components higher in antelope and long-chain components higher in beef. Considerable variation occurred among animals of the same species.     

EFFECTS OF LOW CONCENTRATIONS OF H2O2 ON LIPID OXIDATION AND OF STORAGE AND pH ON NONHEME IRON CONTENT OF RAW BEEF MUSCLE

Ground beef samples were prepared from semimembranosus muscles, and beef muscle residue devoid of heme pigments was prepared by repeated washing of the ground muscle with distilled-deionized water. When ground muscle, or muscle residue samples treated with metmyoglobin-H₂O₂ (4 mg metmyoglobin/g muscle residue; 1:0.1 to 1:1 for molar ratio of metmyoglobin to H₂O²) were stored at 4°C for 0 or 6 days, no changes in nonheme iron content were observed. Similarly, nonheme iron content of stored samples was not affected by pH (5.5, 6.0 or 6.5). While metmyoglobin-H₂O² added to water-extracted beef muscle residue catalyzed the oxidation of the indigenous lipids, treatment of the residue with H₂O² alone had no effect on the oxidation.