Showing papers in "Journal of Food Science in 2001"

Improved Method for Determining Food Protein Degree of Hydrolysis

Abstract: When producing hydrolyzed proteins, it is important to determine the degree of hydrolysis (DH). The trinitro-benzene-sulfonic acid (TNBS) method is well established with regard to enzymatic hydrolysis. However, this method is laborious, cannot be used to follow a hydrolysis reaction continuously, and includes hazardous and unstable chemicals. This paper describes a method based on the reaction of primary amino groups with o- phthaldialdehyde (OPA). The conclusion is that the OPA method of analyzing the DH of protein hydrolyses is more accurate, is easier and faster to carry out, has a broader application range, and is environmentally safer than the TNBS method.

Microbiological aspects of Ozone applications in food: A review

Abstract: Ozone is a powerful antimicrobial agent that is suitable for application In food in the gaseous and aqueous states. Molecular ozone or its decomposition products (for example, hydroxyl radical) inactivate microorganisms rapidly by reacting with intracellular enzymes, nucleic material and components of their cell envelope, spore coats, or viral capsids. Combination of ozone with appropriate initiators (for example, UV or H 2 O 2 ) results in advanced oxidation processes (AOPs) that are potentially effective against the most resistant microorganisms; however, applications of AOPs in food are yet to be developed. When applied to food, ezone is generated on-site and it decomposes quickly, leaving no residues. Ozone is suitable for decontaminating produce, equipment, food-contact surfaces, and processing environment. L'ozone est un puissant antimicrobien, adapte a l'etat gazeux et aqueux, a l'application sur les aliments. L'ozone moleculaire ou ses produits de decomposition inactivent rapidement les microorganismes en reagissant avec les enzymes intracellulaires, les materiaux nucleiques et les composants de la membrane cellulaire. La combinaison de l'ozone avec des initiateurs appropries (UV ou H 2 O 2 ) engendre des procedes d'oxydation avances, potentiellement efficaces contre les microorganismes les plus resistants.

Effects of pH on Caramelization and Maillard Reaction Kinetics in Fructose-Lysine Model Systems

Abstract: The nonenzymatic browning reactions of fructose and fructose-lysine aqueous model systems were investigated at 100 °C between pH 4.0 and pH 12.0 by measuring the loss of reactants and monitoring the pattern of UV-absorbance and brown color development. At all the pH values tested, the loss of fructose was lower in the presence than in the absence of lysine. And, in lysine-containing fructose solution, the sugar disappeared more rapidly than the amino acid. Lysine was moderately lost below pH 8.0. Caramelization of fructose, which accounted for more than 40% of total UV-absorbance and 10 to 36% of brown color development, may therefore lead to overestimating the Maillard reaction in foods.

Extraction, denaturation and hydrophobic properties of rice flour proteins

Abstract: Rice proteins were extracted from defatted rice flour. Turbidity measurement of supernatants revealed isoelectric points of albumin (pH 4.1), globulin (pH 4.3 and pH 7.9), and glutelin (pH 4.8), at which they were precipitated with 82.3 to 93.2% recovery efficiency. Prolamin did not aggregate and precipitate upon pH adjustment, but was precipitated by acetone. Denaturation temperatures (73.3, 78.9, and 82.2 °C) as well as enthalpy values (2.88, 3.14, and 3.79 J/g), of albumin, globulin, and glutelin were different. Prolamin did not show any thermographic denaturation peak. Heat-denaturation of globulin and glutelin resulted in progressive increases in their surface hydrophobicities. Measurement of surface hydrophobicity would be an effective parameter to evaluate rice protein denaturation.

Antimicrobial, Mechanical, and Moisture Barrier Properties of Low pH Whey Protein-based Edible Films Containing p-Aminobenzoic or Sorbic Acids

Abstract: Low pH (5.2) whey protein isolate-based edible films containing p-aminobenzoic acid (PABA) or sorbic acid (SA) were developed and assessed for inhibition of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium DT104 in a disc diffusion assay. Water vapor permeability (WVP), tensile strength (TS), and percent elongation (%E) were also determined. Using 1.5% PABA and SA, average inhibition zone diameters were 21.8, 14.6, 13.9, and 26.7, 10.5, 9.7 mm for L. monocytogenes, E. coli O157:H7, and S. Typhimurium DT104, respectively. Three strains of S. Typhimurium DT104 were resistant to 0.5% SA. Addition of PABA and SA increased %E, but decreased TS. WVP was not affected by 0.5% and 0.75% SA; however, PABA increased WVP. Incorporer des agents antimicrobiens dans des films comestibles est une nouvelle methode pour accroitre l'innocuite et la duree de conservation de produits alimentaires prets a l'emploi. L'acide sorbique et surtout l'acide p-aminobenzoique ont une activite inhibitrice contre L. monocytogenes, E. coli et Salmonella enteridis. Dans cette etude, des films comestibles a base de proteines de lactoserum, a faible pH (5,2), contenant l'un de ces acides sont developpes et testes pour l'inhibition de L. monocytogenes, E. coli et Salmonella typhimurium. 3 souches de S. typhimurium sont resistantes a 0,5% d'acide sorbique. L'addition d'acide p-aminobenzoique et d'acide sorbique augmente le pourcentage d'elongation mais reduit la force de tension. La permeabilite a la vapeur d'eau n'est pas affectee par l'acide sorbique mais augmentee par l'acide p-aminobenzoique.

Pathogen Reduction and Quality of Lettuce Treated with Electrolyzed Oxidizing and Acidified Chlorinated Water

Abstract: The efficacy of electrolyzed oxidizing (EO) and acidified chlorinated water (45 ppm residual chlorine) was evaluated in killing Escherichin coli O157:H7 and Listeria monorytogenes on lettuce. After surface fooculation, each leaf was immersed in 1.5 L of EO or acidified chlotinated water for 1 or 3 min at 22 °C. Compared to a water wash only, the EO water washes significantly decreased mean populations of E. coli O157:H7 and L. monocytogenes by 2.41 and 2.65 log 1 0 CFU per lettuce leaf for 3 min treatments, respectively (p = 0.05), However, the difference between the bactericidal activity of EO and acidified chlorinated waters was not significant (p ≥ 0.05). Change in the quality of lettuce subjected to the different wash treatments was not significant at the end of 2 wk of storage.

Stability to Oxidation of Spray-Dried Fish Oil Powder Microencapsulated Using Milk Ingredients

Abstract: Microencapsulation of fish oil was achieved by spray-drying homogenized emulsions of fish oil using 3 different types of casein as emulsifier and lactose as filler As the degree of aggregation of the casein emulsifier increased, the vacuole volume of the microencapsulated powders decreased The shelf life of the powders increased as the degree of aggregation of the casein emulsifier increased at the high homogenization conditions When micel- lar casein was used as emulsifier, the shelf life also increased as homogenization conditions increased Free fat but not surface fat was inversely related to shelf life Since the type of casein used was confounded with the powder vacuole volume, the increased shelf life may have been due to either factor

Development of a Descriptive Language for Cheddar Cheese

Abstract: A standardized descriptive language for Cheddar cheese flavor was developed and validated. Representative Cheddar cheeses (240) were collected. Fifteen individuals from industry, academia, and government participated in a 3-d roundtable discussion to generate descriptive flavor terms. A highly trained descriptive panel (n = 11) refined the terms and identified references. Cheddar cheeses (24) were presented to the panel for validation with the identified lexicon. The panel differentiated the 24 Cheddar cheeses as determined by univariate and multivariate analysis of variance (P < 0.05). Twenty-seven terms were identified to describe Cheddar flavor. Seventeen descriptive terms were present in most Cheddar cheeses. A standard sensory language for Cheddar cheese will facilitate training and communication between different research groups.

Denaturation Time and Temperature Effects on Solubility, Tensile Properties, and Oxygen Permeability of Whey Protein Edible Films

Abstract: Whey protein film solubility decreased as film-forming solution heating time and temperature increased. No differences were observed in solubility between films soaked in water at 25 °C for 24 h and 100 °C for 4 min. However, the degree of swelling was significantly larger for films soaked at 100 °C. Films became stiffer, stronger and more stretchable as film-forming solution time and temperature were increased. Oxygen permeability (OP) was lower for films made from heat-denatured whey protein than for films made from native whey protein. Results suggest that an increase in covalent cross-linking, as heat denaturation of the whey protein increases, is accountable for film water insolubility, higher tensile properties and lower OP. La solubilite des films comestibles a base de proteines delactoserum diminue quand la temperature et la duree de chauffage augmentent. Les films trempes dans l'eau a 100° pendant 4 minutes gonflent plus que ceux qui sont trempes pendant 24 heures a 25°. Les proprietes mecaniques et elastiques sont meilleures quand la temperature, lors de la formation du film, augmente. La permeabilite a l'oxygene est plus faible quand les proteines de lactoserum sont denaturees thermiquement. Les modification de proprietes lors de la denaturation thermique des proteines sont dues a une augmentation des reticulations par formation de liaisons covalentes.

Depletion Flocculation of Beverage Emulsions by Gum Arabic and Modified Starch

Abstract: The creaming velocity, apparent viscosity, and ultrasonic attenuation spectra (1 to 50 MHz) of 5 wt% n hexadecane oil-in-water emulsions containing different droplet radii (r = 0.15 - 0.7 μm), biopolymer types (gum arabic or modified starch), and biopolymer concentrations (0 to 2.5 wt%) were measured. Depletion flocculation was observed in the emulsions when the nonabsorbed biopolymer concentration exceeded a critical concentration (CFC). The CFC increased with decreasing droplet radius for both biopolymers because the magnitude of the depletion attraction increases with droplet size. The CFC was lower for gum arabic than modified starch because it has a higher effective volume in solution. Depletion flocculation led to an increase in creaming instability and apparent viscosity of the emulsions. Flocculation could be nondestructively monitored by measuring the decrease in ultrasonic attenuation of the emulsions. These results show that depletion flocculation by gum arabic and modified starch can have an adverse effect on the stability of beverage emulsions.

Bihon-Type Noodles from Heat-Moisture-Treated Sweet Potato Starch

Abstract: Sweet potato starch (SPS) has limited uses in the Philippines, but modification of its properties may make it more suitable for use in traditional products that normally use other types of starch, Heat-moisture treatment was applied to native SPS (HMTSPS), which was used as a substrate and composite with maize starch (MS) to produce bihon-type starch noodles, Preliminary quality scoring showed that acceptability scores of raw starch noodles, plain boiled, and sauteed noodles made from 100% HMTSPS and 50% HMTSPS:50% MS were not significantly different from the commercial bihon. However, consumer testing is recommended to further validate acceptability of the sweet potato for bihon. Les bihon sont des pâtes asiatiques traditionnelles fabriquees au Philippines a partir d'amidon de riz, de mais et de haricot mungo. L'amidon de patate douce traite par la chaleur et l'humidite est utilise comme substitut de l'amidon de mais ou melange a l'amidon de mais dans la fabrication des bihon. Le produit semble satisfaisant dans les premiers tests sensoriels.

Thermal Inactivation of Salmonella spp. in Chicken Broth, Beef, Pork, Turkey, and Chicken: Determination of D- and Z-values

Abstract: The heat resistance of 35 Salmonella strains was determined at 55 to 65 °C. No correlation between the heat resistance and the origin of the Salmonella spp. could be established. D-values in chicken broth, using a linear regression, of an 8 Salmonella serotype cocktail were 4.87, 2.72, 1.30, and 0.41 min at 55, 58, 60 and 62 °C, respectively. Using a linear model, the D-values ranged from 4.86 min at 55 °C to 0.38 min at 62 °C. When the 8 Salmonella serotype cocktail was heated in meat, D-values at the common test temperatures of 58 and 60 °C calculated by both approaches were significantly higher (p < 0.05) than those observed in chicken broth.

Milk Protein Coatings Prevent Oxidative Browning of Apples and Potatoes

Abstract: Color analysis on apple and potato slices coated with calcium caseinate or whey protein solutions showed that the 2 coatings efficiently delayed browning by acting as oxygen barriers. The antioxidant properties of the films were realized using a model allowing the release of oxidative species by electrolysis of saline buffer. Whey proteins were a better antioxidant capacity than calcium caseinate. Furthermore, addition of carboxymethyl cellulose (CMC) to the formulations significantly improved their antioxidative power. Best scavenging of oxygen free radicals and reactive oxygen species was found for films based on whey proteins and CMC which inhibited by 75% the formation of colored compounds produced by the reaction of the oxidative species with N,N-diethyl-p-phenylenediamine.

Effects of Ascorbic Acid on Peroxidase and Polyphenoloxidase Activities in Fresh-Cut Cantaloupe Melon

Abstract: Peroxidase (POD) and polyphenol oxidase (PPO) in minimally processed cantaloupe melon (Cucumis melo L. var. reticulatus Naud) were assayed and the effect of ascorbic acid on their respective activities during storage at 4 8 88 8C was determined. POD activity decreased with storage and was inhibited by ascorbate treatment. Two native electrophoretic POD bands with estimated molecular weights 240 and 170 kDa respectively were obtained. Isoelectric focusing separated six acidic POD isozymes with isoelectric points between 5.1 and 6.0, possibly subunits of the POD isozymes. PPO activity in the cantaloupe melon extract was very weak and the fruit's content of oxidiz-

Efficacy of ozone against Escherichia coli O157:H7 on apples.

Abstract: Apples were inoculated with Escherichia coli O157:H7 and treated with ozone. Sanitization treatments were more effective when ozone was bubbled during apple washing than by dipping apples in pre-ozonated water. The corresponding decreases in counts of E. coli O157:H7 during 3-min treatments were 3.7 and 2.6 log10 CFU on apple surface, respectively, compared to < 1 log10 CFU decrease in the stem-calyx region in both delivery methods. Optimum conditions for decontamination of whole apples with ozone included a pretreatment with a wetting agent, followed by bubbling ozone for 3 min in the wash water, which decreased the count of E. coli O157:H7 by 3.3 log10CFU/g.

Physical and Chemical Properties of Edible Films Containing Nisin and Their Action Against Listeria Monocytogenes

Abstract: The effects of hydrophobicity/hydrophilicity of edible films against Listeria monocytogenes strain V7 by various nisin concentrations (4.0 - 160 IU/film disk) and pH values ranging from 2.0 to 8.0 were determined and the mechanical properties and water vapor permeability of films prepared with or without nisin were compared. Surface hydrophobicities (446, 282, 232 and 142, respectively) of whey protein isolates, soy protein isolates, egg albumen and wheat gluten were determined. As the nisin concentration increased, the amount of inhibition progressively increased in all tested films. Using nisin, edible films with higher hydrophobicity values of 280 to 450 units under an acidic environment exerted a greater inhibitory effect against L. monocytogenes. Different interactions of msin with the proteins of the different films resulted in variation in the mechanical properties and water vapor permeabilities of the films tested. Les materiaux d'emballages comestibles et actifs sont une alternative interessante aux polymeres synthetiques. Le but de cette etude est de determiner les effets de differents films comestibles (proteines de ble, proteines de soja, blanc d'oeuf, gluten de ble) sur l'activite de la nisine contre Listeria monocytogenes. L'hydrophobicite, les proprietes mecaniques et les permeabilites a la vapeur d'eau de films prepares avec ou sans nisine sont comparees. Les resultats montrent que le film comestible peut agir en transporteur efficace pour delivrer des agents antimicrobiens a la surface des aliments.

Dry-Aging Effects on Palatability of Beef Longissimus Muscle

Abstract: Beef strip loins and short loins were vacuum aged for 7 or 14 d, then these cuts were dry aged for 7, 14, or 21 d. At 2, 9, and 16 d of post-dry-aging vacuum storage, strip steaks were analyzed for sensory, physical, and microbial differences. Controls were vacuum aged for 14 d. Dry aging for 14 and 21 d produced steaks with greater (P 0.05) dry-aged flavor, tenderness, and juiciness than controls or steaks dry aged for 7 d. Shear forces were lower (P 0.05) for steaks dry aged for 21 d. Time of vacuum storage before and after dry aging had minimal effects on development of dry-aged flavor attributes.

Differences in Gelation Characteristics of Natural Actomyosin from Two Species of Bigeye Snapper, Priacanthus tayenus and Priacanthus macracanthus

Abstract: Natural actomyosin (NAM) of P. tayenus exhibited higher turbidity and storage modulus (G') upon heating, compared to that of P. macracanthus, suggesting the higher protein aggregation and rigidity. At temperature above 35 °C, P. tayenus NAM had higher surface hydrophobicity and disulfide bond formation than P. macracanthus NAM. The α-helix content of NAM from both fish species decreased as the temperature increased, indicating changes in structural conformation during heating. NAM gel from P. tayenus rendered more three-dimensional network than that from P. macracanthus. These results indicated that P. tayenus NAM possessed superior gelling characteristic to P. macracanthus NAM due to the higher aggregation of protein caused by both hydrophobic interaction and disulfide bond. Cette etude compare la capacite a former un gel de l'actomyosine naturelle pendant une gelification thermique entre deux especes de beauclaire, Priacanthus tayenus et Priacanthus macracanthus. Les resultats indiquent que P. tayenus possede des proprietes de gelification superieures a celles de P. marcracanthus, dues a une agregation superieure des proteines causee a la fois par l'interaction hydrophobe et la liaison disulfure.

Texture and other physicochemical properties of whole rice bread.

Abstract: Samples of experimental rice breads baked in a home bread machine were evaluated by physicochemi- cal methods and compared with a local commercial whole-wheat bread. The results showed that rice breads had less specific volume, harder texture, and were more prone to retrogradation during storage than whole wheat bread. All stored breads showed a peak at about 52 8C by differential scanning calorimetry (DSC) analysis, which is character- istic of retrograded starch. However, the DH for rice bread was about 3 times the value of whole-wheat bread, suggesting its strong tendency to retrograde. X-ray diffraction (XRD) evaluation also indicated the appearance of a strong 2u peak between 16.7 8C to 17.0 8C in rice bread than in whole-wheat bread, which is consistent with starch retrogradation.

Texture of Vacuum Microwave Dehydrated Apple Chips as Affected by Calcium Pretreatment, Vacuum Level, and Apple Variety

Abstract: The effects of calcium pretreatment, vacuum level, and apple variety on the texture of apple chips, processed using a combination of air drying and vacuum microwave dehydration (VMD), were determined. Pretreatment of apple slices by immersion in 1-5% aqueous CaCl2 significantly increased crispness of chips as determined by instrumental and sensory analysis; however above 1%, chips were perceived as bitter. Higher vacuum applied during VMD significantly lowered density and increased crispness of chips. This effect was mediated by the vaporization of water in the interior of the chip, which caused expansion of the tissue. Chips made from Fuji apples had higher calcium contents, and were crisper than Red and Golden Delicious apple chips. Microstructure of the chips evaluated by scanning electron microscopy indicated that chips with thicker cell walls and large internal voids were crisper.

Oil Distribution in Fried Potatoes Monitored by Infrared Microspectroscopy

Abstract: During the last decade much attention has been given to investigating oil absorption during frying. Several studies have suggested the key role of the dehydrated crust, which is thought to control the main mechanisms in oil absorption, that is drainage and capillary suction during post-frying cooling. To contribute to a better understanding of these mechanisms, we have used infrared microspectroscopy at the Synchrotron Radiation Source at Daresbury (UK) to monitor the oil distribution in fried potato cylinders. We report what we believe to be the first quantitative data on oil distribution within a fried product. Results show that the oil distribution within the crust reflects the anisotropic nature of the porous region in accordance with the proposed mechanism of oil absorption. Pendant ces dernieres decenies, une grande attention a ete donnee a l'etude de l'absorption d'huile pendant la friture. Pour une meilleure comprehension des mecanismes d'absorption de l'huile, cet article rapporte une etude sur l'utilisation de la microspectrometrie infrarouge a haute resolution spatiale pour suivre la penetration de l'huile dans des cylindres de pommes de terre pendant la friture. L'hypothese proposee est que le croute deshydratee joue un role tres important dans l'absorption de l'huile, de drainage et de succion capillaire pendant le refroidissement apres friture.

Extraction of Gelatin from Megrim (Lepidorhombus boscii) Skins with Several Organic Acids

Abstract: Light-colored, dry collagen was obtained and, after dissolving in warm water, turned into soluble gelatin The type of acid used influenced the gelatin viscoelastic and gelling properties Acetic- and propionic-acid extracts produced the gelatins with the highest elastic modulus, viscous modulus, melting temperature, and gel strength, especially when skins were previously treated with dilute NaOH After such treatment, lactic acid was also shown to be suitable for collagen or gelatin extraction The lowest degree of turbidity was achieved by using citric acid, whereas propionic acid led to the most turbid gelatin No improvements of rheological properties were observed when acid concentration for extraction was increased above 005 M

Reactions of Plant Phenols with Myoglobin: Influence of Chemical Structure of the Phenolic Compounds

Abstract: The reaction products of myoglobin and simple phenolic compounds, with different configurations of hydroxyl groups, and p-quinone were characterized in terms of selected properties (electrophoretic, chromato- graphic and mass spectrometric) and by in vitro digestion. The o-, and p-hydroxyphenols, p-quinone and gallic acid showed high reactivity leading to structural changes in myoglobin. In comparison, ferulic acid and m-hydroxyphenol reacted to only a small extent, especially affecting tryptophan fluorescence of myoglobin. The enzymatic digestion (tryptic, a-chymotryptic, peptic and pancreatic), on the basis of in vitro experiments with derivatized myoglobin,

Extension of the Retail Display Life of Fresh Beef Packaged in Modified Atmosphere by Varying Lighting Conditions

Abstract: The effect of lighting conditions (darkness and either a standard supermarket fluorescent, a low-UV, color-balanced lamp, and the supermarket fluorescent with a UV filter) on the retail display life of fresh beef steaks packaged in a modified atmosphere was studied. Lighting without UV radiation led to a significant delay of meat spoilage, as assessed by surface color (a* and MetMb percentage), lipid oxidation (TBARS value), bacterial counts and sensory evaluation (discoloration and odor). Shelf life of fresh meat was extended from 12 to 22 to 28 d, similar to that of display in the darkness, by using either the low UV lamp or the fluorescent with a UV filter.

Phytosterols and fatty acids in fig (ficus carica, var. mission) fruit and tree components

Abstract: The phytosterol compositions in unsaponifiables of fig (Ficus carica, var. Mission) fruit and 3 structural components of the branches; and the fatty acid composition of fig fruits were studied using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The phytosterols were determined from the trimethylsilyl ether (TMS) derivatives of the unsaponifiable samples. Fourteen compounds were separated from fig fruit; 13, 10, and 6 in bark, stem, and pith, respectively. Sitosterol was the most predominant sterol in all parts. Also detected were campesterol, stigmasterol, and fucosterol. Fatty acids in fig fruit, determined as their methyl esters, were myristic (14:0), palmitic (16:0), stearic (18:0), oleic (18:1), linoleic (18:2), and linolenic (18:3) acids.

Physical and Mechanical Properties of Pea-Protein-based Edible Films

Abstract: Edible films produced from denatured pea protein concentrate (PPC) solution possessed the strength and elasticity to resist handling. Increasing the concentration of the plasticizer (glycerol) in the film decreased tensile strength and elastic modulus, and increased elongation and water vapor permeability (WVP). Very strong and stretch- able films were obtained from 70/30 and 60/40 of PPC/glycerol composition, respectively. The low WVP value was maintained over a range of glycerol concentration from 20% to 40%, in the dry film. Film solubility was not affected significantly by the amount of the plasticizer. The physical and mechanical properties of the PPC films were compa- rable with those of soy protein and whey protein films.

High-Pressure Processing of Orange Juice: Kinetics of Pectinmethylesterase Inactivation

Abstract: A kinetic study of pectinmethylesterase (PME) inactivation in orange juice was conducted. Juice samples were subjected to combinations of high pressure (400, 500, 600 MPa) and thermal (25, 37.5, 50 C) treatments for various time periods. PME inactivation followed a first-order kinetic model with a residual activity of pressure- resistant enzyme remaining. Calculated D-values ranged from 4.6 min to 117.5 min at 600 MPa/50 C and 400 MPa/25 C, respectively. Pressures in excess of 500 MPa resulted in sufficiently fast inactivation rates for economic viability of the process.

Oxymyoglobin oxidation and lipid oxidation in bovine muscle-mechanistic studies

Abstract: The relationship between oxymyoglobin oxidation and lipid oxidation in a bovine muscle homogenate containing FeCl 3 /ascorbate was examined. Increases (P ≤ 0.05) in lipid oxidation preceded Increases in oxymyoglobin oxidation. Lipid oxidation products extracted from an oxidized homogenate bad no significant effect on oxymyoglobin oxidation. Increasing lipid oxidation and oxymyoglobin oxidation was associated with a decrease (P 0.05) in dissolved oxygen. Inclusion of α-tocopherol or Trolox C led to reductions (P ≤ 0.05) in lipid oxidation and oxymyoglobin oxidation, but Trolox C exhibited greater antioxidant potency than α-tocopherol. Hydrogen peroxide had a greater prooxidant effect on oxymyoglobin than the combination of H 2 O 2 and FeCl 2 . Trolox C inhibited H 2 O 2 Induced oxidation of oxymyoglobin. Results support the contention that lipid oxidation is likely to be an important contributor to oxymyoglobin oxidation and meat discoloration. Les relations entre l'oxydation de l'oxyhemoglobine et l'oxydation des lipides dans un homogeneisat de muscle bovin en presence de FeCl 3 /ascorbate ont ete etudiees. L'augmentation de l'oxydation des lipides precede celle de l'oxyhemoglobine, mais les produits d'oxydation des lipides isoles n'ont pas d'effets sur l'oxyhemoglobine. Elles sont associees a une diminution de l'oxygene dissout. L'ajout d'α-tocopherol ou de trolox C provoque une reduction de l'oxydation des lipides et de l'oxyhemoglobine. Le peroxyde d'hydrogene a un effet de prooxydant sur l'oxyhemoglobine. L'ensemble des resultats permet de conclure que l'oxydation des lipides contribue au phenomene d'oxydation de l'oxyhemoglobine et a la decoloration de la viande.

Antimicrobial Treatments for Minimally Processed Cantaloupe Melon

Abstract: Efficacy of decontamination treatments in reducing endogenous microbial populations on cantaloupe and in extending fresh-cut shelf-life were investigated. Composite rind plug samples were washed with water or solutions of sodium hypochlorite, H 2 O 2 , commercial detergent formulations containing dodecylbenzene sulfonic acid and phosphoric acid, or trisodium phosphate, and surviving microbial populations determined. Fresh-cut cubes were prepared aseptically from whole melons given similar treatments, and their visual appearance and bacterial population determined during storage at 4 C. Population reductions on washed rind plugs were 2 weeks.

Effects of High-pressure Processing on Carotenoid Extractability, Antioxidant Activity, Glucose Diffusion, and Water Binding of Tomato Puree (Lycopersicon esculentum Mill.)

Abstract: High-pressure-treated tomato puree was investigated for changes in carotenoid extractability, antioxidant activity, glucose diffusion, and water binding. No effect of pressurization was observed in the total concentrations of the main water-insoluble antioxidants, lycopene and β-carotene, extracted with tetrahydrofuran, but lower recovery of carotenoids with petroleum ether suggested structural changes in the tomato pulp tissue, due to processing. Total antioxidant capacity of the water-soluble fraction was unchanged immediately after pressure treatment, but was better preserved during 21 d at 4 °C, compared with untreated samples. High-pressure treatment resulted also in enhanced water binding. Glucose diffusion through dialysis tubing was lower after high-pressure treatment, leading to a higher glucose retardation index.