Showing papers in "Journal of Food Science in 1995"

Flavonoids and Antioxidant Activity of Fresh Pepper (Capsicum annuum) Cultivars

Abstract: Flavonoid, ascorbic acid and total phenolic content and antioxidant activity of “jalapeno” (Veracruz, Mitla, Tam Mild, Jaloro, Sweet Jalapeno), “yellow wax” [(Hungarian Yellow, Long Hot Yellow, Gold Spike (hybrid)], “Chile” (New Mexico-6, Green Chile), “ancho” (San Luis Ancho), and “serrano” (Hidalgo) peppers were investigated at green or yellow stages of maturity. Major pepper flavonoids were quercetin and luteolin which were present in conjugate forms. Total flavonoid content varied from none detectable to 800 mg/kg after hydrolysis. “Chile”, “yellow wax” and “ancho” peppers had greater flavonoid and ascorbic acid contents and antioxidant activities than “jalapeno” peppers. Sep-Pak C18(tm) bound phenolic compounds, including flavonoids, correlated well with antioxidant activity (r2=0.86). Luteolin had highest antioxidant activity followed by capsaicin and quercetin on equimolar basis.

Antioxidant Activity and Total Phenolics in Different Genotypes of Potato (Solanum tuberosum, L.)

Abstract: Antioxidant activity of potato compared with that of broccoli, onion, carrot and bell peppers was higher than all except broccoli. Patatin appeared to be the major water-soluble compound that showed antioxidant activity. The activity varied among potato cultivars, but was not related to flesh color or total phenolics. Antioxidant activity was evenly distributed within tuber parts and/or sections, except for skin tissue which had the greatest antioxidant activity and total phenolic content. Total phenolics varied among cultivars, with some containing twofold higher concentrations than other cultivars. Phenolic content differences were genotype dependent and not related to flesh color.

Antibacterial Activity of Carvacrol, Citral, and Geraniol against Salmonella typhimurium in Culture Medium and on Fish Cubes

Abstract: Carvacrol, citral and geraniol showed potent antibacterial activity against Salmonella typhimurium and its rifampicin-resistant (RifR) strain as determined in txyptic soy broth and by zone of inhibition on agar-based medium. Carvacrol had the most potent bactericidal activity, with minimum inhibitory and bactericidal concentrations (MIC and MBC) of 250 μg/mL for both tester strains. When tested at 0.5, 1.5 and 3.0% in 1% Tween 20 for bactericidal activity against RifR-S. typhimurium inoculated on fish cubes, carvacrol at 3.0% completely killed the inoculated bacteria, while geraniol killed most of the bacteria, and citral killed the least. Carvacrol and geranial showed potent antibacterial activity at 1.5%. Bactericidal activity became more evident as storage of fish cubes at 4°C lengthened. The comparable inhibition of these strains of Salmonella and species of Gram-negative bacteria by carvacrol and geraniol support their application as potential antibacterial agents in food systems.

Cholesterol Oxides in Foods of Animal Origin

Abstract: The earliest discovery of an oxidation product of cholesterol from a natural source was reported in 1940. Additional discoveries of cholesterol oxidation products (COPS) in edible food products accelerated in the 1980s as gas chromatography and high performance liquid chromatography detection methods were improved. COPS have been found in several foods including liquid eggs and dried egg products, milk and milk products, meat and meat products, marine food products, and other processed foods. Compelling evidence demonstrates that several cholesterol oxides are cytotoxic, atherogenic, mutagenic, and carcinogenic. Therefore, the presence of COPS in foods raises questions about the safety of consumption of some products.

Texture of Cheddar Cheese as Influenced by Fat Reduction

Abstract: Cheddar cheeses with five different fat levels (34, 32, 27, 21, and 13 %) were manufactured in a randomized block design experiment and replicated four times. Cheeses were ripened for 4 months at 7°C. Microstructure was studied using Scanning Electron Microscopy (SEM). Texture characteristics (adhesiveness, cohesiveness, hardness, and springiness) were determined by Texture Profile Analysis (TPA) using the Instron Universal Testing Machine and a trained sensory panel. Scanning electron micrographs showed that the open-intricate microstructure of the cheeses was lost with a decrease in fat content. Hardness and springiness increased while adhesiveness and cohesiveness of the cheeses decreased with decreasing fat content. Texture attributes were influenced by the nature of the protein matrix that resulted due to fat removal.

Edible Packaging Films Based on Fish Myofibrillar Proteins: Formulation and Functional Properties

Abstract: Biopackaging materials based on fish myofibrillar proteins have been developed. The effects of protein concentration, pH, temperature and storage time before casting on the apparent viscosity of the film forming solution (FFS) were evaluated using experimental design methodology. The first objective was to determine a feasible experimental range for film-forming. The pH and protein concentration had strong interactive effects on FFS viscosity. During FFS storage before casting, partial degradation of high molecular weight protein components led to decreased viscosity, allowing thin layer casting. In the experimental range for film-forming, none of the conditions affected film functional properties. Standard conditions were determined at: pH 3.0, 2.0g protein/100g FFS, 25°C and 6 hr storage. The functional properties of the standard biopackaging were slightly better than those that determined for known protein-based films, with tensile strength close to those of low density polyethylene films.

Microencapsulation by Spray Drying Ethyl Caprylate in Whey Protein and Carbohydrate Wall Systems

Abstract: Ethyl caprylate was microencapsulated by spray drying in wall systems consisting of whey protein in combination with maltodextrin (DE 5–15) or corn syrup solids (DE 24). Ester particle-size distribution in the infeed emulsion was adversely affected by high proportions of low DE maltodextrin. Ester retention during drying was affected (P < 0.05) by type of carbohydrate used and its proportion and ranged from 70 to 91%. The proportion of solvent extractable core was reduced with increasing DE value of carbohydrate. Combinations of whey proteins and high DE mal-todextrins or corn syrup solids are effective wall systems for microencapsulation of volatiles.

Screening potato starch for novel properties using differential scanning calorimetry.

Abstract: Thermal and other physicochemical properties of starch from 42 potato genotypes were studied to find those with unique properties for food use, and to analyze relationships between thermal and other physicochemical properties. Onset and peak transition temperatures and gelatinization enthalpy intercorrelated. Transition temperatures intercorrelated with pasting temperature using a Brabender Visco-amylograph. Gelatinization entbalpy correlated with Brabender pasting temperature and peak paste viscosity, and onset temperature correlated with phosphorus content. Genotype E55–3.5 with highest onset and peak transition temperatures also had highest phosphorus and peak Brabender viscosity. DSC might be useful for rapidly screening samples of <1g starch for such. Potato starch DSC characteristics did not correlate with amylose, intrinsic viscosity, or water-binding. For 10 genotypes from successive years, correlations were observed for pasting temperature (r = 0.83), phosphorus content (r = 0.80), and stability ratio (r = 0.66). Direct comparison between samples from consecutive years showed good reproducibility for amylose, but not for phosphorus or pasting.

Stability of Spray‐Dried Encapsulated Carrot Carotenes

Abstract: Encapsulation with various dextrose equivalent (DE) hydrolyzed starches affected stability of α- and β-carotene in spray-dried carrot powders. Degradation of α- and β-carotene during storage of the powders at temperatures ranging from 37 to 65°C followed first-order kinetics and both degraded at the same rate. Hydrolyzed starch of 36.5 DE was superior to 4, 15, and 25 DE in improving retention of the carotenes. Carotenes encapsulated with 36.5DE hydrolyzed starch had a predicted half-life of 450 days at 21°C compared to 2 days for carrot juice spray dried alone. Increasing the proportion of carrier decreased the carotene degradation rate and similarly decreased surface carotene. Air was critical in carotene stability, but exposure of encapsulated carrot powders to light did not accelerate degradation.

Conjugated Linoleic Acid Concentrations in Dairy Products as Affected by Processing and Storage

Abstract: Total conjugated linoleic acid (CLA) concentrations increased 1.32 fold in salted and 1.27 in unsalted butter but did not alter the ratio of 9-cis, 11-trans to total CLA. Nonfat yogurt showed an increase in CLA content with processing (5.25 mg total CLA/g fat) compared to unprocessed raw material (4.40 mg CLA/g fat). No changes in CLA content was observed in processed dairy products such as lowfat yogurt, regular yogurt, lowfat and regular ice cream, sour cream or cheeses such as Mozzarella, Gouda and Cheddar. Storage did not affect CLA concentration in any products suggesting that CLA is a stable component.

Heat-resistance of Escherichia coli O157:H7 in meat and poultry as affected by product composition

Abstract: The effects of fat level and low fat formulation on survival of Escherichia coli O157 :H7 isolate 204P heated in ground beef [7%, 10% and 20% fat], pork sausage [7%, 10%, and 30% fat], chicken (3% and 11% fat), and turkey (3% and 11% fat) were determined by D- and z-values. D-values for E. coli O157 :H7 in lowest fat products were lower than in traditional beef and pork products (P < 0.05). Overall, higher fat levels in all products resulted in higher D-values. D 60 values (min) ranged from 0.45-0.47 in beef, 0.37-0.55 in pork sausage, 0.38-0.55 in chicken and 0.55-0.58 in turkey. D 55 and D 50 values were respectively longer. Z-values ranged from 4.4-4.8°C. Product composition affected lethality of heat to E. coli O157 :H7.

Ozone Storage Effects on Anthocyanin Content and Fungal Growth in Blackberries

Abstract: Ozone exposure was assessed for storage of thornless blackberries which are prone to fungal decay. Blackberries were harvested and stored for 12 days at 2°C in 0.0, 0.1, and 0.3 ppm ozone. Berries were evaluated for fungal decay, anthocyanins, color and peroxidase (POD) activity. Ozone storage suppressed fungal development for 12 days, while 20% of control fruits showed decay. The main mold was Botrytis cinerea. Ozone storage did not cause observable injury or defects. By 12 days, anthocyanin content of juice was similar to initial levels for all treatments. Surface color was better retained in 0.1 and 0.3 ppm-stored berries by 5 days and in 0.3 ppm berries by 12 days, by hue angle values. POD was greater in controls and 0.1 ppm samples, and was lowest in 0.3 ppm fruits by 12 days. Ozone storage resulted in market quality extension.

Sensory and Texture Quality of Dry-Cured Ham as Affected by Endogenous Cathepsin B Activity and Muscle Composition

Abstract: Hams were processed with standard cure adjuncts under two drying temperatures and analyzed after aging for 7 mo. Dried hams revealed that flavor and texture traits were affected by moisture and nonprotein nitrogen (NPN) content and that NPN was enhanced by greater cathepsin B activity, lower salt levels and higher temperature. Two major defects of dry-cured ham, mushy mouthfeel and surface white film, occurred in about 15% of samples. Most of these hams had abnormal NPN values and were shown to originate from meat with high enzyme activity and low protein content. We concluded that this type of meat is prone to uncontrolled proteolysis and related undesired traits, and to be a potential hazard in dry-cured hams cured with less salt.

Polyphenoloxidase from Amasya apple

Abstract: Polyphenoloxidase (PPO) of Amasya apple was partially purified by (NH4)2SO4 precipitation and dialysis. The sample was used for characterization of the PPO. Optimum pH were 7.0, 9.0, 8.6 and 6.6 on substrates catechol, 4-methyl catechol, pyrogallol and L-dopa respectively. Catechol was the most suitable for Amasya apple PPO. The optimum temperature for maximum PPO activity was 18°C with catechol. Of seven inhibitors tested, the strongest was L-cysteine. Effectiveness of inhibitors increased in the order: thiourea, glutathione, β-mercaptoethanol, sodium cyanide, ascorbic acid, sodium metabisulfide, and L-cysteine. The KM was 34 mM of catechol. The activation energy with catechol was 107 cal/mol. In electrophoretic separation, three isoenzymes were detected with both catechol and L-dopa substrates.

Kinetics of ascorbic acid loss and nonenzymatic browning in orange juice serum: experimental rate constants.

Abstract: The kinetics of ascorbic acid loss and nonenzymatic browning in clarified orange juice (serum) were investigated in an anaerobic environment from 70.3 to 97.6°C and from 11.7 to 80.6°Brix. Data were fitted to first-order kinetic models. Rate constants of ascorbic acid degradation in serum were not different from rate constants in whole juice. Activation energies were 30 kcal/mol and largely independent of solids concentration. Rate constants of browning pigment formation were 30-50% greater in serum. Activation energies were 19-25 kcal/mol and increased slightly with solids concentration.

Biochemical changes and sensory quality of shredded and MA-packaged iceberg lettuce

Abstract: Cultivars of shredded iceberg lettuce (Lactuca sativu L.) ‘Saladin’, ‘Santis’, ‘Telda’ and ‘Roxette’ responded in a parallel way to four modified atmosphere (MA) packaging treatments. Moderate vacuum packaging (mvp) in 80 μm polyethylene (PE) inhibited enzymatic browning over 10-day storage at 5°C. When lettuce was packaged in 80% O2, 20% CO2 (80/20), more browning occured in SL3-bags (59 μm multilayer coextruded film) than in PE-bags. Polyphenol oxidase activity declined during storage in all 4 atmospheres, with lowest activity in PE-80/20. Endogenous ascorbic acid (AA) did not act as an efficient antioxidant in delaying browning. Total carbohydrate content (TC) declined slightly during storage. Tristimulus color measurements correlated highly with visual ratings.

Low Temperature Blanching Effects on Chemistry, Firmness and Structure of Canned Green Beans and Carrots

Abstract: Green beans and carrots were canned using extended blanching at 64-65 o C and added calcium and/or acid. Firmer products resulted from all treatments but lowered pH was most effective. Blanched green beans were firmer with lower pectin esterification, indicating pectin methyl esterase activity. Green beans and carrots treated with calcium and/or acid and then cooked were firmer than controls. Acid exhibited a firming effect, perhaps by loosening tissue, while calcium reduced the influence of heat. Instrumental bioyield values correlated with sensory results of canned green beans; bioyield may result from a scleriformic layer. Microscopy showed firmer beans had intact middle lamellae while softer samples contained separated cells. These data suggest that the treatments rendered pectates in the middle lamella less heat labile

Starch and Egg White lnfluence on Properties of Bologna Sausage as Related to Fat Content

Abstract: Surface Response Methodology (RSM) was used for simultaneous analysis of levels of added starch (S) and egg white (EW) and their effects on binding and textural characteristics of meat emulsions as related to their fat content (F). Regression models were significant (P 0.05) for pH, cohesiveness, springiness and work of penetration. Of the three variables studied, starch most influenced binding and textural properties. Starch reduced cooking loss and purge loss and increased hardness, chewiness and penetration force. Egg white affected texture (increased hardness, chewiness and penetration force) and did not affect binding properties. Each individual variable was generally not influenced by the other two.

Flavor and Oxidative Stability of Roasted High Oleic Acid Peanuts

Abstract: A new peanut line has been developed at the University of Florida with about 80% oleic and 3% linoleic acid. Volatiles and sensory characteristics of roasted normal and high oleic acid peanuts stored at 25°C were compared. Volatiles were analyzed using adsorbent trapping and GCMS, a 20-member trained panel was used for sensory evaluation, and a GC sniffer port was used to evaluate odor characteristics of volatile isolates. Peroxide values were lower for high oleic (HO) peanuts than normal peanuts during storage at 25°C and 40°C. The hexanal content of the peanuts was higher for normal than HO. Peanutty flavor was more stable for HO than normal after 6 wk storage. Painty and cardboard flavors were higher in normal peanuts than HO during storage. Differences for both painty and cardboard flavors were significant after 6 wk storage. Pyrazines were more stable in HO peanuts. Shelf life was estimated from sensory data to be two times longer in HO peanuts.

Oil Uptake in Deep Fat Frying as Affected by Porosity

Abstract: The porosity of a restructured potato product ranged from 0.089 to 0.168 after fluctuating subfreezing storage temperatures. A linear relation was found between oil uptake during frying and porosity prior to frying. Bulk and particle density, and porosity were monitored for up to 5 min during deep-fat frying. Particle density increased gradually, bulk density decreased and porosity increased noticeably. After an initial short period, oil uptake correlated linearly with porosity of the fried product. A new term, “net porosity” which excluded the void volume occupied by oil was developed for describing the oil uptake mechanism.

Sensory Characteristics of Frankfurters as Affected by Fat, Salt, and pH

Abstract: Acceptable processing and flavor profile characteristics of frankfurters were achieved near a pH of 6.0. As salt increased, hardness, juiciness, saltiness, and flavor intensity scores increased. As fat increased, juiciness scores decreased (at salt levels > 1.3%) due to substitution of water for fat. In addition, increased fat resulted in decreased off-flavor. Model predictions suggested that acceptable frankfurters could be manufactured with a minimum of 11.25% fat and 1.3% salt at pH 6.0.

Consumer Acceptability of Beef Steak Tenderness in the Home and Restaurant

Abstract: Acceptability of beef steak tenderness in home and restaurant environments was evaluated by 62 consumers. Steaks (loin, ribeye, or bottom and top round) were consumed by each panelist in their home and in a fine dining restaurant. Each consumer rated steaks for tenderness and overall acceptability in the home (over a 2-mo period) and one steak per week (over a 7-wk period) in the restaurant. Acceptability for steaks consumed at home and in the restaurant ranked between 3 (moderately tough) and 4 (slightly tough) on an 8-point scale. The Warner-Bratzler Shear force transition level for beef tenderness acceptability in the home was between 4.6 and 5.0 kg and in the restaurant between 4.3 and 5.2 kg. The unacceptable level of beef steak tenderness was ≤4.3 kg. Results suggested that consumers were more critical of beef tenderness in the home than in restaurants. Consumer responses may have been influenced by receiving free meals in the home or restaurant, as well as by the dining environment.

Inactivation of Pseudomonas fluorescens by High Voltage Electric Pulses

Abstract: A 30 kV pulsed power treatment system was designed and developed to process fluid materials. Our objective was to investigate the effects of high voltage electric pulses on microbial inactivation in an aqueous solution under different operating conditions and fluid properties. Electric field strength at 10 kV/cm for 10 pulses (2 sec pulse period and 2 μsec pulse width) with a spike of reverse polarity resulted in significant microbial control. P. fluorescens in various aqueous solutions were reduced in population by more than six log cycles. However, the critical electric field strength was affected by the nature of the pulse waveform across the treatment chamber which, in turn, was a function of electrode distance and fluid properties. Sudden charge reversal immediately at the end of a pulse provided maximum microbial decay.

Microwave Pre-treatment for Sun-Dried Raisins

Abstract: Commercial sun-drying of raisins requires a long time, and chemical pretreatments are used to increase the drying rate. The feasibility of improving the sun-drying process of grapes by microwaves was investigated. Sultana seedless grapes, dipped in alkali solution, were pre-treated in a domestic microwave oven and dried by direct solar radiation. Microwave pre treatment reduced the moisture content by 10–20%. The microwave-treated grapes dried nearly two times faster than the controls. Blanching in boiling water had the same effect on the drying rate as microwaves. Color and appearance of treated grapes were comparable to commercial products.

Heat Stability of Oil-in-Water Emulsions Containing Milk Proteins: Effect of Ionic Strength and pH

Abstract: ABSTRAC Emulsions (20 wt% soybean oil; 2 wt% protein) made with caseinate at pH 7 and with whey protein isolate (WPI) at pH 7 and 3 were stable to heating at 90 and 121°C WPI emulsions destabilized at pH values between 35 and 40 In the presence of KCI (125–200 mM), large particles were formed in WPI emulsions at pH 3 and the emulsions were viscous At pH 7, moderate concentrations of KCI decreased the heat stability and gels were formed KCI had less effect on WPI emulsions made at pH 3 Combining the emulsions with caseinate allowed some control of the heat-induced gelation

Edible Coatings on Frozen King Salmon: Effect of Whey Protein Isolate and Acetylated Monoglycerides on Moisture Loss and Lipid Oxidation

Abstract: Whey protein isolate (WPI) and acetylated monoglyceride (AMG) coatings were evaluated for effectiveness against moisture loss and lipid oxidation of frozen King salmon. A model gel material was also used to screen coatings for effectiveness against moisture loss. Coatings of low-melting-point AMG used alone or after applying WPI solution or WPI powder were effective in reducing the rate of moisture loss by 4265% during the first 3 wk of storage. Onset of lipid oxidation was delayed and peak peroxide values were reduced in samples coated with WPI solution/antioxidant overspray or those containing low-meltingpoint AMGs. No differences in effectiveness were found among the coating treatments.

Variations in Radiation Sensitivity of Foodborne Pathogens Associated with the Suspending Meat

Abstract: Longissimus dorsi from beef, pork, and lamb and turkey breast and leg meats were inoculated with Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus, and the gamma radiation resistance of the pathogens were determined under identical conditions. At 5 o C the respective radiation D-values of E. coli O157:H7 and L. monocytogenes did not vary with the suspending meat. The D-value for a mixture of Salmonella spp. was significantly lower on pork than on beef, lamb, turkey breast, and turkey leg meats. The D-value for S. aureus was significantly lower on lamb and mechanically deboned chicken meat than on the other meats. All values were, nevertheless, within expected ranges

Surimi Gel Colors as Affected by Moisture Content and Physical Conditions

Abstract: Colors (CIE L * , a * , and b * ) of Alaska pollock (Theragra chalcogramma) and Pacific whiting (Merluccius productus) surimi gels were evaluated and related to compositional and physical conditions during preparation and measurements. Ten samples were used in each treatment. Water addition, sample size, species, cooking and test temperatures, and freeze/thaw affected lightness (L * ) and yellowness (b * ) values, while outside light conditions at measurement did not affect colors. Greenness (-a * ) values were less affected by all conditions

Grape Pomace as a Potential Food Fiber

Abstract: Grape pomace, and insoluble and soluble dietary fiber (DF) fractions, obtained by enzymatic-gravimetric methods, were analyzed for neutral sugars, uranic acids, Klason lignin and amino acids. DF constituted 80% of dry matter, IDF was the major fraction. The main neutral sugar constituent of IDF was glucose. The major part was cellulose and the remainder, along with xylose, was a xyloglucan, which also contained fucose. Uranic acids accounted for 64% of SDF and a high amount of arabinose, galactose and mannose were also included in that fraction. Proteins were not well solubilized by the assay enzymes. During the isolation of DF fractions a considerable solubilization of polyphenols was observed. These compounds were associated with Klason lignin in the starting material. Composition of DF fractions enables grape pomace to be considered a useful fiber-rich food ingredient.

Enzymatic hydrolysis of crayfish processing by-products

Abstract: Ten commercial proteases (neutral and alkaline) were evaluated for hydrolysis of crayfish processing by-products (CPBs). Hydrolysis conditions were optimized for the alkaline protease OptimaseTM APL-440 by response surface methodology (RSM). Two model equations were proposed with regard to effects of pH, temperature (T), time (t), enzyme/ substrate (E/S) ratio, and substrate concentration (S) on the amount of 0.3M TCA soluble peptides (TSP) and degree of hydrolysis (DH). Interaction effects between pH and T were observed (P<0.001). Based on TSP, optimum hydrolysis conditions were determined to be pH 8–9, 65°C, 2.5 hr reaction time, 75%(w/v) substrate concentration, and 0.3% (v/w) enzyme.