bluuebunny/crossref_metadata_2025 huggingface dataset:
Debittering of a Tryptic Digest of Bovine p‐casein Using Porcine Kidney General Aminopeptidase and X‐Prolydipeptidyl Aminopeptidase from Lactococcus lactis subsp. cremoris AM2
Authors: Barry C.M. , O'Cuinn G. , Harrington D. , O'Callaghan D.M. , Fitzgerald R.J.
Published: July 2006

ABSTRACT: The role of leucine aminopeptidase (LAP) from pig kidney cytosol and X‐prolyldipeptidyl aminopeptidase (Pep X) from Lactococcus lactis subsp. cremoris AM2 in the hydrolysis and debittering of a tryptic digest of β‐casein was studied. Hydrolysis was monitored by quantifying the release of primary amino groups and bitterness by use of a trained sensory panel. Sequential incubation of the bitter tryptic hydrolysate with LAP, Pep X and LAP resulted in higher levels of hydrolysis and significantly (P < 0.001) lower levels of bitterness than incubation with LAP alone. The results demonstrate the central role proline‐specific aminopeptidases can play in the hydrolysis and debittering of food protein hydrolysates.
Instrumental and Expert Assessment of Mahon Cheese Texture
Authors: Benedito J. , Gonzalez R. , Rosselló C. , Mulet A.
Published: July 2006

ABSTRACT: To improve Mahon cheese texture assessment, the relationship between instrumental and sensory measurements was sought. For that purpose 30 pieces of Mahon cheese from different batches and 2 different manufacturers were examined. Textural characteristics at different curing times were evaluated by uniaxial compression, puncture, and sensory analysis. Significant linear correlations were found between instrumental and sensory measurements. A logarithmic model (Weber‐Fechner) fitted data better than a linear one. Only 1 factor was extracted when considering all the instrumental and sensory variables, thus indicating that both sets of measurements are related to the same phenomenon. The best predictors for Mahon cheese sensory attributes were found to be cheese moisture, deformability modulus, and slope in puncture.
Rheological Characterization of Rice Flour‐Based Batters
Authors: Mukprasirt A. , Herald T.J. , Flores R.A.
Published: July 2006

ABSTRACT: The flow behavior and the applicability of rheological models to predict the viscosity of rice flour‐based batter (RFBB) for deep‐fat frying at 5,15, and 25 °C were investigated. The Herschel‐Bulkley model was found to be the best fit for all RFBBs formulated with different ratios of rice to corn flour, oxidized corn starch, and methylcellulose (R2= 0.85–0.99). Rheological parameters depended on RFBB compositions, temperature, and shear rate. The relationship between temperature and RFBB apparent viscosity can be predicted within shear rate range between 30 to 132 s−1. Correlation coefficient (r) of model validation decreased as temperature increased.
Quality Index Method Developed for Raw Gilthead Seabream (Sparus aurata)
Authors: Huidobro A. , Pastor A. , Tejada M.
Published: July 2006

ABSTRACT: Sensory assessment is one of the principal methods of measuring fish quality. One of the most interesting sensory methods at the moment is the quality index method (QIM). The QIM provides weighted evaluation of the key parameters in deterioration of individual species, assigning demerit points according to the importance of the parameter. This paper describes the development of a QIM for gilthead seabream (Sparus aurata). As result of this study, a QIM is proposed for this species. The appearance of skin and slime, flesh elasticity, odor of the fish, clarity and shape of the eyes, and color and odor of the gills are the parameters included which gave a total of 15 demerit points. The index scored lower when the fish was washed.
Development of a Meat‐Like Process Flavoring from Soybean‐Based Enzyme‐Hydrolyzed Vegetable Protein (E‐HVP)
Authors: Wu Y.‐F. , Baek H.H. , Gerard P.D. , Cadwallader K.R.
Published: July 2006

ABSTRACT: Response surface methodology (RSM) was used to develop a meat‐like process flavoring agent from enzyme‐hydrolyzed vegetable protein (E‐HVP). Five factors were evaluated: pH (3.6 to 8.4), temperature (51 to 99 °C), heating period (0.3 to 2.7 h), amount of ribose (0 to 1 × KHmol) and amount of cysteine (0 to 1 × 10 3mol). Sensory analysis limited to aroma in terms of overall liking and intensity of specific aroma attributes was investigated. The aroma attributes measured included bean‐like, potato‐like, Brussels sprouts‐like, molasses‐like, chicken‐like, beef‐like, egg‐like, roasted and apple sauce‐like). Based on the fitted surfaces and consumer test data (overall liking), the optimum reaction conditions for production of a meat‐like flavoring were pH 6,99 °C reaction temperature, 1.5 h heating time, 5 × 10−4 mol of ribose and 5 × 10−4 mol of cysteine.
Tomato Flavor and Aroma Quality as Affected by Storage Temperature
Authors: Maul F. , Sargent S.A. , Sims C.A. , Baldwin E.A. , Balaban M.O. , Huber D.J.
Published: July 2006

ABSTRACT: Studies were conducted to describe flavor and aroma in ripe tomatoes stored at 5, 10, 12.5 and 20 °C. Fruit stored for 2 d below 20 °C were rated by trained sensory panelists as significantly lower (P < 0.05) in ripe aroma, tomato flavor, compared to those stored at 20 °C. Fruit stored at 5 °C for 4 d were rated significantly lower in ripe aroma, sweetness, tomato flavor, and significantly higher in sourness, compared to those stored at 20 °C. Following 8 and 12 d storage, fruit at 5 °C were rated lowest in ripe aroma and sweetness. Significant reductions in important GC aroma volatiles and chemical composition and electronic nose analyses concurred with sensory descriptor ratings.
Soy Protein Fortification Affects Sensory, Chemical, and Microbiological Properties of Dairy Yogurts
Authors: Drake M.A. , Chen X.Q. , Tamarapu S. , Leenanon B.
Published: July 2006

ABSTRACT: Chemical, microbiological, and sensory properties for low fat yogurts fortified with 0,1, 2.5, or 5% soy protein concentrate were determined through 1 mo storage at 5 °C. Yogurts were adjusted to equivalent total solids with nonfat dried milk. Microbiological counts, fermentation time, and final developed acidity were not affected by soy protein. Instrumental viscosity and sensory thickness, soy aroma, and soy flavor increased with soy protein addition (P 0.05). Soy flavor and aroma did not increase with storage time. Yogurt with 5% soy protein was darker, more chalky, and less sweet compared to control yogurt or yogurts with lower concentrations of soy protein (P 0.05). Yogurts with 1 or 2.5% soy protein were most similar to control yogurt.
Effect of Process Conditions on the Physical and Sensory Properties of Extruded Oat‐Corn Puff
Authors: Liu Y. , Hsieh F. , Heymann H. , Huff H.E.
Published: July 2006

ABSTRACT: The effect of processing variables, including screw speed (200,300, and 400 rpm), moisture content (18, 19.5, and 21%), and four different percentages (55,70,85, and 100%) of oat flour, on the extrudate physical properties (expansion, bulk density, and texture profiles) and sensory properties were studied. Increasing the percentage of oat flour resulted in extrudates with a lower specific length, higher bulk density, lower lightness, higher redness, lower yellowness, higher hardness, and lower springiness, gumminess, and chewiness. Higher moisture content reduced expansion, except for the 100% oat flour puffs. Screw speed had no significant effect on the bulk density, specific length, and expansion ratio. Principal Component Analysis showed that decreasing moisture content and increasing screw speed resulted in increased product temperature, which was highly correlated with attributes of a more expanded product such as lightness, crispness, shininess, and an open cell structure. With a higher screw speed and a higher product temperature, corn‐related flavors were more likely to develop. High correlations between physical and sensory properties were observed.
Impact of Supercritical Carbon Dioxide and High Pressure on Lipoxygenase and Peroxidase Activity
Authors: TEDJO W. , ESHTIAGHI M.N. , KNORR D.
Published: July 2006

The effects of supercritical carbon dioxide (ScCO2) treatment and high hydrostatic pressure treatment on the activities of lipoxygenase (LOX) and peroxidase (POD) were studied. Hydrostatic pressure treatment (240 MPa, 55 °C, 15 min) of LOX and POD in 30% sucrose solutions without buffer led to approximately 80% and approximately 50% residual activity, respectively. Application of ScCO2 (35.2 MPa, 40 °C, 15 min for LOX and 62.1 MPa, 55 °C, 15 min for POD) achieved approximately 35% LOX and approximately 65% POD inactivity in 30 % sucrose solutions. Total inactivation of LOX (10.3 MPa, 50 °C and 15 min) and of POD (62.1 MPa, 55 °C and 15 min) could be achieved through ScCO2 treatment of unbuffered solution. Increasing the concentration of sucrose and buffering (pH range 4 to 9) of enzyme solutions resulted in increased resistance of the enzymes to ScCO2 treatment.
Antioxidant Activity of Whey in a Salmon Oil Emulsion
Authors: Tong L.M. , Sasaki S. , McClements D.J. , Decker E.A.
Published: July 2006

The antioxidant capabilities of whey in a Tween 20TM‐stabilized salmon emulsion were investigated. Whey fractions inhibited formation of thiobarbituric acid reactive substances (TBARS) and lipid peroxides in a 10 % salmon oil emulsion in the order of whey > high‐molecular‐weight (HMW) fraction > low‐molecular‐weight fraction. Heating the HMW fraction exposed sulfhydryls, with optimum exposure at 80 °C. Heating the HMW fraction above 80 °C increased antioxidant activity. The HMW fraction of whey (80 °C) alone, α‐tocopherol (40 ppm) alone, and their combination inhibited TBARS 59,19 and 86%, respectively, at 21 d of storage. Sulfhydryls oxidized before a‐tocopherol, suggesting that sulfhydryls are the primary antioxidant. Results indicate that whey proteins could be useful antioxidants in food emulsions.
Reduction of Microflora of Whole Pickling Cucumbers by Blanching
Authors: Breidt F. , Hayes J.S. , Fleming H.P.
Published: July 2006

There is increasing interest in developing methods to control the presence of pathogenic and spoilage microorganisms on fresh fruits and vegetables. Blanching whole pickling cucumbers for 15 s at 80 °C reduced microbial cell counts by 2 to 3 log cycles from an initial population of typically 106 CFU/g. Vegetative microorganisms survived this blanching process (10–fold greater in number than the spore count), presumably because they were located beneath the surface of the cucumber. The sensitivity to heat of selected populations was measured by determining D values for pooled microorganisms (termed D values) isolated from fresh cucumbers. The Enterobacteriaceae population and the total aerobic microflora had similar Dp values to each other and to the D value for a selected lactic acid bacterium.
Inoculum Size of Clostridium botulinum 56A Spores Influences Time‐to‐Detection and Percent Growth‐Positive Samples
Authors: Zhao L. , Montville T.J. , Schaffner D.W.
Published: July 2006

The influence of inoculum size on the growth kinetics of Clostridium botulinum 56A and percentage of growth‐positive samples was studied in a complete factorial design with factors of inoculum size (1, 100, or 10,000 spores), pH, and sodium‐chloride concentration. Growth was followed hourly as change in A620. Polynomial regression was used to analyze the data. The time‐to‐detection and percent growth‐positive samples were significantly affected by inoculum size and its quadratic term. When inoculum size increased from 1 to 100 spores/sample, the percent growth‐positive samples increased, and the time‐to‐detection decreased. When the inoculum was 1000 spores/sample or higher, there was little additional effect. Inoculum size might influence results through simple probability or quorum sensing. The maximum growth rate was independent of inoculum levels.
Antimicrobial Efficacy of a Peroxyacetic/Octanoic Acid Mixture in Fresh‐Cut‐Vegetable Process Waters
Authors: Hilgren J.D. , Salverda J.A.
Published: July 2006

The antimicrobial efficacy of a peroxyacetic/octanoic acid mixture for fruit and vegetable process water was compared to peroxyacetic acid alone. Rate‐of‐kill studies usingyeast and molds indicated that the peroxyacetic/octanoic acid mixture had greater antifungal efficacy. In tests conducted during vegetable processing, use of the peroxyacetic/octanoic acid mixture was associated with lower numbers of yeast and molds in process water. In 1 example, lower numbers of yeast and molds in potato processing water containing the peroxyacetic acid/octanoic mixture were associated with lower yeast and mold counts on potatoes. Peroxyacetic/octanoic acid mixtures may offer processors using peroxyacetic acid a way to improve fungal reduction in recycled water processes.
Oxidative Stability and Sensory Attributes of Prerigor Cooked Beef Steak
Authors: Wu J.Y. , Mills E.W. , Henning W.R.
Published: July 2006

Beef sirloin tip steaks from 12 steer carcasses were cooked prerigor and postrigor using three heating methods and stored at 4 °C or ‐20 °C. Prerigor cooked steak had lower cook loss, higher pH, higher shear force, and sensory hardness than postrigor cooked steak. Conventional oven cooking produced the lowest cook loss for prerigor steak. Prerigor cooked steak had lower thiobarbituric acid value than postrigor cooked samples after 2 wks at 4 °C or 3 mo at ‐20 °C. Sensory warmed‐over flavor intensity scores were low and showed no differences between prerigor and postrigor cooked steaks for refrigerated or frozen samples.
Textural Changes in Mushrooms (Agaricus bisporus) Associated with Tissue Ultrastructure and Composition
Authors: Zivanovic S. , Busher R.W. , Kim K.S.
Published: July 2006

The objective of this study was to determine ultrastructural and compositional changes in fresh mushrooms associated with adverse changes in texture during 9 d of post‐harvest storage at 12 °C. Mushroom softening (2.6N to 1.5N, puncturing force) was consistent with toughening (19.2N to 33.0N, gumminess). Protein and total carbohydrate content declined, but chitin content increased during mushroom storage. Most polysaccharides were extracted after deacetylation and depolymerization of chitin, indicating that structural glucans were mainly bound with acetylglucosamine polymers. Softening paralleled expansion of intercellular space at the pilei surface, hyphae shrinkage, central vacuole disruption, and loss of proteins (r = 0.94) and polysaccharides (r = 0.84), while toughening was associated with increased chitin content (r = 0.95).
Optimum Postmortem Chilled Storage Temperature for Summer and Winter Acclimated, Rested, Chinook Salmon (Oncorhynchus tshawytscha) White Muscle
Authors: Jerrett A.R. , Law R.A. , Holland A.J. , Cleaver S.E. , Ford S.C.
Published: July 2006

Chemical anaesthesia (AQUI‐STM) was used to harvest 2 groups of tank‐reared chinook salmon (Oncorhynchus tshawytscha), naturally acclimated to summer (18.8 °C) and winter (10.7 and 12.4 °C) temperatures, in a “rested”state. Carcasses were stored in 35% seawater at temperatures between approximately 2 and 19 °C to investigate the effects of acclimation and storage temperature on the postmortem metabolic rate of rested epaxial white muscle tissue. Muscle pH, [lactate], and adenosine triphosphate/inosine monophosphate measurements made 20 h postharvest indicated that winter acclimated fish were 2.2 times more sensitive to temperature than summer fish. A 3rd group of winter acclimated fish, stored between –1.2 and 6 °C, indicated that significant cold injury only occurred on freezing.
Low‐voltage Electrical Stimulation Effects on Proteolysis and Lamb Tenderness
Authors: Lee S. , Polidori P. , Kauffman R.G. , Kim B.C.
Published: July 2006

Lamb carcasses were subjected to low‐voltage electrical stimulation (ES; 28 V, 60 Hz) within 5 min postmortem (PM). After ES, the longissimus thoracis (LT) and semimembranosus (SM) muscles were removed to investigate subsequent biochemical changes. The pH values of the ES muscles declined rapidly until the 1st 3 h PM (p < 0.05). The activities of μ‐calpain and calpastatin in ES muscles decreased significantly after 10 h PM (p < 0.05). Both ES LT and SM muscles tended to have lower shear‐force values, which suggested ES might accelerate activation of calpains as well as glycolytic rate, thereby improving muscle tenderness. Differences in thin and troponin‐T degradation between treatments were also observed with time PM.
Comparison of Cheeses Made from Milk Having Normal and High Oleic Fatty Acid Compositions
Authors: AIGSTER A. , SIMS C. , STAPLES C. , SCHMIDT R. , O'KEEFE S.F.
Published: July 2006

Calcium salts of high‐oleic sunflower oil (> 86% oleic acid) were prepared and fed at 0% and 7.5% of diet dry matter weight to 8 Holstein cows in early‐ to mid‐lactation in a cross‐over experimental design. Oleic acid content of milk fat increased from 26% to over 40% and cholesterol‐raising saturates were reduced from 41% to 33%. Latin American white cheese, queso blanco, was produced from modified and normal milk. No differences in firmness were found between cheeses using penetration‐compression testing with an Instron machine. Sensory difference tests indicated no significant differences between cheeses. Latin American white cheeses made with high oleic milk are similar to traditional cheese.
Degradation of Lycopene, α‐Carotene, and β‐Carotene During Lipid Peroxidation
Authors: Anguelova T. , Warthesen J.
Published: July 2006

The stability and antioxidant effectiveness of lycopene, a‐carotene, and b‐carotene were compared during oxidation of methyl linoleate at 37 and 60 °C. Two carotene concentrations, 80 or 160 mg/g of methyl linoleate, were used to determine a concentration effect. At 37 °C, the degradation rates were: lycopene > β‐carotene > α‐carotene. Lycopene and α‐carotene inhibited hydroperoxide formation, lycopene being the more effective antioxidant. β‐Carotene inhibited hydroperoxide formation at the lower concentration but did not show an antioxidant effect at the higher concentration. At 60 °C, the carotenes degraded 6 to 8 times faster than at 37 °C and did not show an antioxidant effect. BHT or α‐tocopherol effectively suppressed the hydroperoxide formation and degradation of the carotenes.
Survival and Growth of Vibrio cholerae O1, Salmonella typhi, and Escherichia coli O157:H7 in Alfalfa Sprouts
Authors: Castro‐Rosas J. , Escartín E.F.
Published: July 2006

The survival and growth of Vibrio cholerae O1, Salmonella typhi, and Escherichia coli O157:H7 during germination and sprouting of disinfected alfalfa seeds and alfalfa sprouts was determined. All pathogens showed ability to grow during germination and sprouting, reaching counts of approximately 6.0 log10 CFU/g after 24 h. No growth was observed for any pathogen when the sprouts were inoculated after 24 h of seed germination. At this time, the background microflora was abundant. Numbers of pathogens inoculated on alfalfa sprouts decreased less than 1 log10 CFU/g over 15 d of refrigeration. Alfalfa sprouts can be an important factor contributing to the endemicity for typhoid fever and cholera in México.
Sensory and Physical Properties of Peanut Butter Treated with Palm Oil and Hydrogenated Vegetable Oil to Prevent Oil Separation
Authors: Gills L.A. , Resurreccion A.V.A.
Published: July 2006

Sensory properties of peanut butters stabilized with 0%, 1.5%, 2.0%, and 2.5% palm oil (PO) and hydrogenated vegetable oil (HVO) and stored for 153 d at 0, 21, 30, and 45 °C were determined. Oxidized flavor in unstabilized peanut butter (UPB) and PO was compared with HVO to determine shelf‐life. Shelf‐life of UPB stored at 21, 30, and 45 °C was 75 d. Peanut butter with 2.5% palm oil had a shelf‐life of 113 d. Regression analysis indicated a linear association for the attributes graininess, hardness, oiliness, mouthdryness, and spreadability with day, treatment, and temperature. No linear relationships existed between stickiness, adhesiveness, and gumminess and day, temperature, and levels of PO.
Thermal Stability of Bovine Milk Immunoglobulin G (IgG) and the Effect of Added Thermal Protectants on the Stability
Authors: Chen C.‐C. , Tu Y.‐Y. , Chang H.‐M.
Published: July 2006

D and z values and some thermodynamic parameters of immunoglobulin G (IgG) in phosphate buffer solution (PBS) (0.15 M NaCl/0.01 M phosphate buffer, pH 7.0) and colostral whey, with or without the presence of thermal protectants, were calculated in model systems. The D and z values for separated IgG in PBS were much lower than those for separated IgG in 20% glycerol, whey, and whey with 20% glycerol. IgG in colostral whey showed larger D and z values with the protectants. The heat denaturing rate constants at 70‐82°C for separated IgG in PBS were larger than those of IgG in colostral whey; and the energies of activation for separated IgG in PBS, 0.2% glutamic acid, 10% whole milk, 20% maltose and 20% glycerol were also larger.
Gelation and Water Binding Properties of Transglutaminase‐treated Skim Milk Powder
Authors: Imm J.Y. , Lian P. , Lee C.M.
Published: July 2006

Transglutaminase (TGase)‐treated skim milk powder (TG‐SMP) was prepared by freeze‐drying skim milk after TGase treatment (10 U/g milk protein, 40°C for 3 h), followed by TGase inactivation at 85°C for 5 min. TGase modification resulted in significant increases in hardness and water holding capacity (WHC) of heat‐induced gels (10% protein, w/v). A marked increase in storage modulus (G′) of TG‐SMP upon heating suggests that TG‐SMP has a greater gelling ability than control‐SMP (C‐SMP) prepared with predenatured TGase. Acid gels prepared from TG‐SMP had a significantly higher WHC at all solid levels (12%, 14%, and 16%) tested and formed a more elastic network than C‐SMP.
Covalent Crosslinking in Heated Protein Systems
Authors: Mohammed Z.H. , Hill S.E. , Mitchell J.R.
Published: July 2006

Changes in the solubility (in water or in 1% sodium dodecyl sulfate plus 1%β‐mercaptoethanol), isoelectric point, and degree of browning were followed for a range of food proteins when they were heated to 105 to 145°C at 3 relative humidities (RH). In general, there is a decrease in solubility with increasing RH and temperature of heating, but most proteins also showed an increase in solubility on extensive heating. The order for the proteins, based on the temperatures at which an increase in solubility occurred was: gelatin < gluten < soya isolate, sodium caseinate < egg albumin, bovine serum albumin < whey isolate, milk powder, β‐lactoglobulin. The bonds that could be formed and broken during this thermal treatment are considered.
Plasma Protein and Soy Fiber Content Effect on Bologna Sausage Properties as Influenced by Fat Level
Authors: Cofrades S. , Guerra M.A. , Carballo J. , Fernández‐Martín F. , Colmenero F. Jiménez
Published: July 2006

The effects of plasma protein (PP) and soy fiber (SF) content on the properties (binding properties, color, and texture) of bologna sausages as influenced by fat level (F) were assessed by response surface methodology (RSM). Higher soy fiber and plasma protein contents favored the formation of harder, chewier structures with improved fat and water binding properties. Fat reduction decreased textural properties and increased weight loss. Cooking loss was affected (P < 0.05) by interactions between PP and F and chewiness was affected (P < 0.05) by interactions between SF and F. Plasma protein influenced binding and textural properties more than soy fiber and was, therefore, thought best to limit the effect of fat reduction.
Fermentation of Monascus purpureus on Bacterial Cellulose‐nata and the Color Stability of Monascus‐nata Complex
Authors: Sheu F. , Wang C.L. , Shyu Y.T.
Published: July 2006

Nata, a bacterial cellulose produced by Acetobacter aceti ssp. xylinum, was colored by means of fermentation with Monascus purpureus. Scanning electron microscopy (SEM) observations showed that the Monascus mycelium could grow through the cellulose network of nata. Rice powder as a major carbon source and monosodium glutamate (MSG) as a nitrogen source gave an appealing coloration after 12 d of fermentation at 30 °C. Compared to dyed nata, the color of the Monascus‐nata complex had better resistance to washing, heat, freezing, acidification, and alkalization. A 66.1% decolorization was found under irradiation with 366 nm ultraviolet light after 36 h. The Monascus‐nata complex has the potential to be a new vegetarian foodstuff.
Changes in Anthocyanins and Polyphenolics During Juice Processing of Highbush Blueberries (Vaccinium corymbosum L.)
Authors: Skrede G. , Wrolstad R.E. , Durst R.W.
Published: July 2006

Frozen blueberries (Vaccinium corymbosum L.) were processed into juice and concentrate, and the changes in anthocyanin pigments and polyphenolics (cinnamates, procyanidins, flavonol glycosides) were monitored. While juice yield was 83%, only 32% of the anthocyanins were recovered in single‐strength juice. Flavonol, procyanidin and chlorogenic acid recoveries in juice were 35%, 43%, and 53%, respectively. The proportion of polyphenolics remaining in the press‐cake residue ranged from 1% (chlorogenic acid) to 18% (anthocyanins). Pronounced losses of anthocyanins and polyphenolics during milling and depectinization are believed to be due to native polyphenol oxidase. Losses during concentration ranged from 1.5% (anthocyanins) to 20% (procyanidins). Striking changes occurred in the anthocyanin profile with malvidin glycosides being most stable and delphinidin glycosides the least.
Relaxation Time Spectrum of Hydrogels by CONTIN Analysis
Authors: Mao R. , Tang J. , Swanson B.G.
Published: July 2006

CONTIN is a general‐purpose program for inverting noisy linear algebraic and integral equations by means of inverse Laplace transform. This study explored the application of CONTIN analysis to determine the relaxation time distribution spectra for food gels, including gellan, carrageenan, whey protein, and gelatin gels, based on stress‐relaxation data. CONTIN results represent the continuous relaxation time spectra when the number of the terms in the discrete Maxwell stress‐relaxation model approached infinity. The CONTIN results for gellan gels were correlated to the texture properties of gels from compression tests with respect to the effects of calcium concentrations. CONTIN analysis may be a very effective tool in elucidating the microstructural properties of a hydrogel from mechanical testing.
Gelation Characteristics of Paddlefish (Polyodon spathula) Surimi Under Different Heating Conditions
Authors: Lou X. , Wang C. , Xiong Y.L. , Wang B. , Mims S.D.
Published: July 2006

Gelation properties of paddlefish surimi were investigated with different heating procedures. Without pre‐incubation, gel strength of paddlefish surimi increased as temperature increased from 40 to 60 °C. Pre‐incubation at 40 °C caused myosin degradation and reduced gel strength by 55% compared to the control. Pre‐incubation at 70 °C followed by cooking at 90 °C produced gels with maximum strength. Isothermal heating between 40 and 50 °C produced rheological transitions between 0 and 15 min. Beef plasma powder reduced myosin degradation and enhanced gelation of surimi incubated around 40 °C. These results indicated that the gel‐weakening phenomenon in paddlefish surimi was due to the degradation of myosin by some endogenous protease(s).
Differences in Hollow Volumes in Cooked Rice Grains with Various Amylose Contents as Determined by NMR Micro Imaging
Authors: Horigane A.K. , Engelaar W.M.H.G. , Toyoshima H. , Ono H. , Sakai M. , Okubo A. , Nagata T.
Published: July 2006

The presence of hollows in cooked rice grains found before in the cultivar Koshihikari was confirmed for 4 more cultivars with various amylose contents. The size, shape, and total volume of hollows differed between cultivars. Hollow volumes increased with grain volume and length before 100 °C was reached, but subsequently decreased during prolonged boiling. The previously proposed mechanism, describing sealing by gelatinized starch of cracks formed during soaking, seemed accurate for all 5 cultivars. Based on the hypothetical model of their formation, a relationship between amylose content and hollow formation was assumed. However, no correlation existed between final hollow volume and shape on 1 side and individual parameters such as flour gelatinization and amylose content on the other side.
Chemical and Functional Properties of Oxidatively Modified Beef Heart Surimi Stored at 2 °C
Authors: Parkington J.K. , Xiong Y.L. , Blanchard S.P. , Xiong S. , Wang B. , Srinivasan S. , Froning G.W.
Published: July 2006

Beef heart surimi was prepared using 4 washing conditions: (1) sodium phosphate buffer alone, (2) buffer 1 NaCl, (3) buffer 1 propyl gallate, and (4) buffer 1 sodium tripolyphosphate. Surimi samples were stored at 2 8C and analyzed periodically for protein oxidation, emulsifying properties, and dynamic gelling characteristics. Degree of oxidation differed among washing treatments. Addition of propyl gallate and sodium tripolyphosphate inhibited lipid oxidation but did not prevent protein oxidation. Gel elasticity increased and emulsifying activity decreased for all surimi samples during storage, coinciding with myosin aggregation. Modification of beef heart surimi functionality can be achieved through different washing processes.
Plasticizing—Antiplasticizing Effects of Water on Physical Properties of Tapioca Starch Films in the Glassy State
Authors: Chang Y.P. , Cheah P.B. , Seow C.C.
Published: July 2006

The effects of moisture sorption on physical properties of native and cross‐linked starch films in the glassy state were studied. Water played a dual role as a plasticizer or an antiplasticizer, depending on the physical property measured. Plasticizing effects were clearly evident in the case of the calorimetric glass transition temperature (Tg), tensile modulus, linear expansion, and water vapor permeability. In contrast, antiplasticization by water resulted in maxima in tensile strength, strain‐at‐break, and toughness of films that were observed at an intermediate moisture content ranging from 4% to 8% (RVP 0.1 to 0.4). The seemingly contradictory effects of water on mechanical properties associated with lower and higher deformation of starch films were reconciled by assigning different roles to water operating primarily via opposite entropic/free volume effects. Relationships, if any, between DSC thermal events and mechanical antiplasticization were not apparent.
Modeling the Growth/No‐Growth Interface of Zygosaccharomyces bailii in Mango Puree
Authors: López‐Malo A. , Palou E.
Published: July 2006

Probabilistic microbial modeling using logistic regression was used to predict critical temperatures to inhibit for at least 35 d Zygosaccharomyces bailii growth in a pH 3.5 mango puree formulated with 1000 ppm of potassium sorbate (KS) or sodium benzoate (NaB) at selected aw (0.99, 0.98, or 0.97). The probability of growth was calculated, thereby ascertaining the set conditions and critical temperatures required inhibiting yeast growth for different storage times. Using the logistic model, with a growth probability of 0.05, critical temperatures were higher for KS than for NaB. Use of KS to inhibit Z. bailii growth enabled for mango puree 30 d of storage at 6.4 °C.
Blanch Time and Cultivar Effects on Quality of Frozen and Stored Corn and Broccoli
Authors: Barrett D.M. , Garcia E.L. , Russell G.F. , Ramirez E. , Shirazi A.
Published: July 2006

Three corn and 2 broccoli cultivars were steam blanched for various times and evaluated for residual enzyme activity. Lipoxygenase was inactivated in 4 min in supersweet corn, while sweet corn required a 6‐min blanch; peroxidase was inactivated in 8 min. Inactivation of broccoli lipoxygenase, peroxidase, and cystine lyase was achieved in 90 s. Blanched samples were stored 9 mo at –18 °C, then analyzed for color, texture, hexanal, free fatty acids, and sugars. Firmness increased significantly with blanching in both commodities, then declined. Short blanch treatments targeting lipoxygenase inactivation positively affected color and texture of both corn and broccoli. Changes in current industry practices are recommended.
1H NMR Studies of Water in Chicken Breast Marinated with Different Phosphates
Authors: Li Rongrong , Kerr W.L. , Toledo R.T. , Carpenter J.A.
Published: July 2006

ABSTRACT: Samples of boneless, skinless chicken breasts were vacuum tumbled in 7% salt and 1.2% of either disodium pyrophosphate, tetrasodium pyrophosphate, tetrapotassium pyrophosphate, sodium tripolyphosphate, or glass phosphate, and studied using 1H NMR. Spin‐lattice (T1) values ranged from 568 to 642 ms, with highest values seen for phosphate‐treated samples. Increases with treatment were attributed to changes in moisture. Cooking reduced T1 values due to loss of moisture and setting of the protein gel. Compression produced further reductions in T1 values. Little dispersion in R2 with pulse spacing (τ) was observed for uncooked samples.
Purification of Glycomacropeptide from Caseinate Hydrolysate by Gel Chromatography and Treatment with Acidic Solution
Authors: Nakano T. , Ozimek L.
Published: July 2006

ABSTRACT: Glycomacropeptide (GMP) was purified from chymosin‐hydrolyzed caseinate solution by the procedure involving: (1) gel chromatography on Sephacryl S‐200 at pH 7.0 to obtain a crude GMP fraction; (2) addition of acidic solution, pH 3.5 to the crude glycomacropeptide to precipitate contaminating protein and/or peptide; and (3) re‐chromatography of the material soluble in the acidic solution on Sephacryl S‐200 at pH 3.5. The purified GMP accounted for 5.3% of dry weight of caseinate hydrolysate, and 0.7% of dry weight of sodium caseinate powder. The preparation was of considerably high purity with its amino‐acid composition showing only traces (each < 1 residue / peptide) of arginine, histidine, phenylalanine, and tyrosine, the amino acids that do not occur in GMP.
Porcine Plasma Proteins as a Surimi Protease Inhibitor: Effects on Actomyosin Gelation
Authors: Visessanguan W. , Benjakul S. , An H.
Published: July 2006

Effect of porcine plasma proteins (PPP) on thermal gelation of actomyosin in the presence and absence of fish proteinase was studied using a dynamic rheological test. Substantial decreases in development rate and magnitude of gel modulus were observed by the addition of proteinase to actomyosin gels. PPP was effective in protecting a myosin‐heavy chain from proteolytic degradation, however, PPP itself interfered with the formation of actomyosin gel. Lower gel modulus was observed with actomyosin gels developed with higher concentrations of PPP added. Overall, PPP reversed the loss of gel modulus by the proteinase, however, the recovered gel modulus was only as high as those containing PPP only. These results implicated that, although PPP may revert autolytic activity in surimi, it interfaces with actomyosin gelation.
Interaction of Low Molecular Weight Phenolics with Proteins (BSA)
Authors: Bartolomé B. , Estrella I. , Hernández M.T.
Published: July 2006

Mixtures of bovine serum albumin (BSA) and several low molecular weight phenolics were incubated and fractionated using G‐50 Sephadex chromatography. Fractions corresponding to the protein and the possible phenolic‐protein complexes and fractions corresponding to the free phenolics were collected, and their phenolic content was determined. Among the selected commercial phenolic standards tested (p‐coumaric acid, p‐hydroxybenzoic acid, protocatechuic acid, caffeic acid and (+)‐catechin), the strongest BSA‐binding affinity was demonstrated by 3,4‐dihydroxy benzoic and cinnamic acids (protocatechuic acid and caffeic acid), whereas p‐hydroxybenzoic acid did not interact with BSA. The methodology was also applied to a phenolic extract obtained from lentils containing p‐coumaric acid, a p‐coumaric acid derivative, (+)‐catechin and procyanidins B3 [(+)‐catechin‐(4αÕ8)‐(+)‐catechin] and B1 [(‐)‐epicatechin‐(4αÕ8)‐(+)‐catechin]. Interactions observed among the lentil phenolics and BSA were comparable to those observed among the commercial phenolic standards and BSA.
Moisture Diffusion and Desorption Isotherms for Banana
Authors: Phoungchandang S. , Woods J.L.
Published: July 2006

ABSTRACT: The desorption isotherms for whole peeled banana, convection dried in warm air, have been measured and fitted by the Modified‐Oswin and Modified‐Chung‐Pfost equations. The equations agreed with the water activity observed in commercial sun‐dried banana packs from Thailand. The convective drying curves for peeled banana were determined and fitted by the Newton (exponential) and Diffusion models. The Newton model was found more effective, probably due to a surface resistance that develops during drying. The drying constant, K in the Newton model, was fitted to banana temperature by the Arrhenius equation. Moisture diffusivity results agreed with previous work, including the activation energy in the Arrhenius equation.
Predicting Lethal Effect of Ultrasonic Waves Under Pressure Treatments on Listeria monocytogenes ATCC 15313 by Power Measurements
Authors: Mantas P. , Pagán R. , Raso J.
Published: July 2006

ABSTRACT: Power measurements (input power to ultrasound generator, input power to transducer, and ultrasonic power entering the treatment medium) were compared to the inactivation effect of ultrasound under pressure (manosonication, MS) treatments on Listeria monocytogenes ATCC 15313 in pH 7 citrate‐phosphate buffer. A linear relationship was found between the power entering the treatment medium, measured by a calorimetric method, and the decimal reduction times of L. monocytogenes under different experimental conditions. Therefore, the lethal effect of MS treatments could be estimated from simple calorimetric measurements.
Statistical Variability Of Heat Penetration Parameters in Relation to Process Design
Authors: Smout C. , Loey A. Van , Hendrickx M. , Beirlant J.
Published: July 2006

ABSTRACT: This study was undertaken to develop statistical approaches that can deal with variations in heating parameters when designing processes. In this context, the statistical variability of heat penetration parameters of a large amount of both hand‐filled and machine‐filled containers was investigated in different case studies. Two new statistical approaches are presented: an univariate and a bivariate statistical method. Both approaches appear successful for statistically based determination of heating parameters for process design. The statistical approaches also enable estimating the minimum number of heat penetration measurements to give reliable values to use in calculating safe thermal processes.
Milk Protein Coatings Prevent Oxidative Browning of Apples and Potatoes
Authors: LE Tien C. , Vachon C. , Mateescu M.‐A. , Lacroix M.
Published: July 2006

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.
Effect of SDS on Acid Milk Coagulability
Authors: Lefebvre‐cases E. , DE LA Fuente B. TARODO , Cuq J.L.
Published: July 2006

ABSTRACT To study the importance of hydrophobic interaction on the mechanism of acid milk gel formation, milk coagulation process was monitored at 30 °C in presence of various levels of sodium dodecyl sulphate (SDS). As a function of the SDS concentration, acid milk coagulability was either enhanced or reduced. Main pH‐induced biochemical changes were preserved despite the presence of SDS (such as pH‐induced demineralization and pH‐induced protein solubilization). It could be assumed that SDS‐modified casein micelles ability to coagulate by lowering of pH might seem to be governed essentially by the level of SDS‐induced k‐casein micellar dissociation, at natural milk pH.
Phytase and Citric Acid Supplementation in Whole‐Wheat Bread Improves Phytate‐phosphorus Release and Iron Dialyzability
Authors: Porres J.M. , Etcheverry P. , Miller D.D. , Lei X.G.
Published: July 2006

ABSTRACT Conditions were established for maximizing phytate breakdown in whole‐wheat flour (wwf) during bread baking and for assessing the effects of dephytinization on dialyzability of intrinsic and added iron in the bread. Three different sources of phytase (Aspergillus niger, A. fumigatus, and Escherichia coli) with various levels of citric acid (0 to 6.25 g/kg wwf) were used. Supplementing citric acid at 6.25 g/kg wwf enhanced phytate degradation catalyzed by intrinsic phytase from 42% in the untreated bread to 69% (P < 0.05). Supplementation of microbial phytase (285 units/kg) plus 3.125 or 6.25 g citric acid/kg wwf further enhanced phytate reduction up to 85%. Compared with the untreated bread, citric acid alone and the combination of citric acid and phytase enhanced total iron dialyzability by 12‐ and 15‐fold, respectively, while the combination of phytase, citric acid, and ascorbic acid improved total iron dialyzability in the mixture by 24‐fold.
Effect of α‐Tocopherol, β‐Carotene, and Sodium Tripolyphosphate on Lipid Oxidation of Refrigerated, Cooked Ground Turkey and Ground Pork
Authors: Vara‐ubol S. , Bowers J.A.
Published: July 2006

ABSTRACT α‐Tocopherol and β‐carotene at 0.03% levels and sodium tripolyphosphate (STP) at 0.2% and 0.3% levels, alone and in combination, were added to ground turkey and ground pork. Hexanal was measured after cooking and storage at 4 °C for 2, 4, or 6 d. α‐Tocopherol alone significantly reduced hexanal of stored, cooked, turkey but had no effect in pork. STP was more effective than α‐tocopherol and a combination of α‐tocopherol with STP resulted in enhanced antioxidant activity. Hexanal of pork with 0.03%α‐tocopherol plus 0.3% STP did not increase significantly during storage, and that of turkey increased only slightly. β‐Carotene and salt (1% NaCl) had no effect on hexanal.
Sausage Structure Analysis
Authors: Ripoche A. , LE Guern L. , Martin J.L. , Taylor R.G. , Vendeuvre J.L.
Published: July 2006

ABSTRACT Effect of salt content, grinder pore size, and mixing temperature on structure of sausage meat were investigated after 1 and 4 d. Protein solubility, texture characteristics and muscle ultrastructure were measured. Cellular structure is conserved when salt amount is under 0.3% for all temperatures and grinder pore sizes, or when salt amount is of 0.8% for a temperature higher than 6 °C or a grinding size of 10 mm. Cellular structure is modified when salt amount is above 1.3% whatever the temperature and grinding size, or when salt amount is of 0.8% for a temperature below 6 °C or a grinding size of 1.5 mm. The use of statistical tools permitted to distinguish modified meat from intact preparations.
Concentration Measurement by Acoustic Reflectance
Authors: Saggin R. , Coupland J.N.
Published: July 2006

ABSTRACT The speed of sound and the acoustic reflection coefficient of sucrose (0 to 60 wt%), glycerol (0 to 50 wt%), sodium chloride (0 to 27 wt%) solutions and tomato ketchup (0 to 100 wt%) dispersions were measured using a modified pulse‐echo technique (2.25 MHz transducer, 20 °C). The density of all solutions is measured using a vibrating tube densitometer. All measured parameters are linear functions of concentration. Ultrasonic reflectance can provide equally precise measurements of concentration as conventional ultrasonic velocity measurements. For all samples except concentrated ketchup (> 50 wt%), measured reflectance is demonstrated to be a function of ultrasonic velocity and density.
Inactivation Kinetics of Enzymes by Using Continuous Treatment with Microbubbles of Supercritical Carbon Dioxide
Authors: Yoshimura T. , Shimoda M. , Ishikawa H. , Miyake M. , Hayakawa I. , Matsumoto K. , Osajima Y.
Published: July 2006

ABSTRACT Enzyme inactivation using a new apparatus for continuous treatment with microbubbles supercritical carbon dioxide (SC‐CO2) was investigated. D value of a‐amylase (5.0±1.2 min) subjected to microbubbles of SC‐CO2 treatment (microbubbles‐SCT) at 35 °C, 30 MPa was lower than that (227 ± 15.9 min) subjected to heat treatment (HT) at 70 °C. D value of acid protease was reduced by microbubbles‐SCT at 50 °C, 30 MPa (15.4 ± 4.1 min), compared to HT at 50 °C (233 ± 15.2 min). The activation energy for the inactivation of acid protease (135 ± 8.3 kJ mol‐1) by microbubbles‐SCT was 1 half of that (259 ± 9.0 kJ mol‐1) by HT. These results indicated that continuous treatment with microbubbles of SC‐CO2 was effective for enzyme inactivation.
Denaturation Time and Temperature Effects on Solubility, Tensile Properties, and Oxygen Permeability of Whey Protein Edible Films
Authors: Perez‐gago M.B. , Krochta J.M.
Published: July 2006

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.
Thermal Inactivation of Salmonella spp. and Listeria innocua in the Chicken Breast Patties Processed in a Pilot‐Scale Air‐Convection Oven
Authors: Murphy R.Y. , Johnson E.R. , Duncan L.K. , Davis M.D. , Johnson M.G. , Marcy J.A.
Published: July 2006

ABSTRACT Salmonella spp. or Listeria innocua containing chicken patties were processed via a pilot‐scale air‐convection oven to a final temperature of 55 to 80 °C. Thermal processing was conducted at an air temperature of 149 °C, an air velocity of 7.1 to 12.7 m3/min, and a wet bulb temperature of 39 to 98 °C. The cooking time was correlated with cooking conditions using a standardized least square regression model. The models were developed to correlate cooking time and the thermal inactivation of Salmonella or Listeria with cooking conditions. The thermal lethality of Salmonella and Listeria increased with increasing product temperature and wet bulb temperature. This study bridged the gap between laboratory studies and commercial applications and will help commercial processors to evaluate and validate their thermal processes.
Characterization and Classification of Streptococcus Thermophilus and Lactobacillus Delbrueckii Subsp. Bulgaricus Strains Isolated from Traditional Greek Yogurts
Authors: Xanthopoulos V. , Petridis D. , Tzanetakis N.
Published: July 2006

ABSTRACT Streptococcus thermophilus (74 strains) and Lactobacillus delbrueckii subsp. bulgaricus (75 strains) isolates from traditional Greek yogurts were tested on the basis of their acidification kinetics, acidity, viscosity, and aroma compounds formation in milk pure cultures. Strains of Lb. bulgaricus presented greater viscosity values, higher acidification activity and produced more acetaldehyde at culture pH 4.6 than S. thermophilus strains. Acetoin was formed only by the latter strains, while diacetyl was not detected in either species. Application of cluster and discriminant analysis permitted definition of distinct groups of strains and of the most significant variables to discriminate among them. Finally, classification and regression tree analysis allowed clusters characterization by critical values of the most discriminant variables. Evaluation of results as above could be a useful tool to select, through a large number of screened strains, the suitable starters for specific purposes.