Search

This study used flow cytometry (FC), epifluorescent microscopy (EM), and conventional culture media (PC) to evaluate the potential for high-pressure throttling (HPT) to produce injury in E. coli. E. coli cells suspended at a concentration of approximately 8 log (CFU/mL) in Butterfield's phosphate buffer and UHT skimmed milk, were treated with HPT at pressures ranging from 35 to 283 MPa. Cells were stained with SYTO 9 and propidium iodide (Live/Dead Baclight kit) to assess their membrane integrity. MacConkey and Tryptone Soy agars and a modification of the thin agar layer method were used to determine injured and non-injured cells. PC results indicated a reduction in E. coli counts as pressure increased but no significant injured population was detected in either matrix. However, FC and EM observations indicated that the membrane integrity of a portion of the bacterial population was affected by HPT, producing different degrees of cell injury that could be sublethal. The percentage of this heterogeneous population increased with applied pressure. These results reassert the importance of understanding the potential of new processing treatments to produce sublethally-injured bacteria, and developing appropriate detection techniques. Practical Application High-pressure throttling could be an interesting technology to pasteurize liquid products in a continuous way. There is not a lot of information available for the researchers with this equipment. Thus, the information provided in this article will attract much attention from the scientific and industrial communities.

A Shockwave Power Reactor consisting of an annulus with a rotating pock-marked inner cylinder was used to induce hydrodynamic cavitation in calcium-fortified apple juice flowing in the annular space. Lethality on Saccharomyces cerevisiae was assessed at processing temperatures of 65 and 76.7 degrees C. Details of the novel equipment design were presented and energy consumption was compared to conventional and pulsed electric fields processing technologies. The mean log cycle reduction of S. cerevisiae was 6.27 CFU/mL and all treatments resulted in nonrecoverable viable cells. Induced lethality from hydrodynamic cavitation on S. cerevisiae exceeded the predicted values based on experimentally determined thermal resistance. Rotation of 3000 and 3600 rpm at flow rates greater than 1.0 L/min raised product temperature from 20 to 65.6 or 76.7 degrees C, respectively, and energy input was less than 220 kJ/kg. Conversion efficiency from electrical to thermal was 55% to 84%. Hydrodynamic cavitation enhanced lethality of spoilage microorganisms in minimally processed juices and reduced energy usage.

A finite element method was used to solve the unsteady state heat transfer equations for heating of turkeys in a conventional electric oven. Breast, and thigh and wing joint temperature in 5.9, 6.8, 8.6, 9.5, and 10.4 kg turkeys were simulated. A surface heat transfer coefficient of 19.252 W/m 2 K determined by transient temperature measurements in the same oven, was used. Thermal conductivity measured using a line heat source probe from 0 to 80°C was 0.464 W/mK. Simulated temperatures were within 1.33, 1.47, and 1.22°C of experimental values of temperature in the breast, thigh, and wing joint, respectively. Initial temperature 1 , 2, and 3°C lower than 4°C required additional baking time of 16, 22, and 27 min., respectively for the thigh joint to reach the target

Plots of log (water activity/mole fraction water) against the square of the mole fraction solute, usually give straight lines having slopes K. Norrish (J. Food Tech 1966, 1: 251 used K derived for binary solutions in an equation for calculating water activities of multicomponent systems, but this equation gave inaccurate results when used on solutions where a deviation from linearity occurs, or when the linear portion of the plot does not go through the origin. By using both intercept and slope, and adding a correction factor that corresponds to the contribution of the intercept to the total solute interactions to Norrish's equation for multicomponent systems, an equation was derived that accurately predicted water activities of multicomponent systems. This concept of utilizing the intercept was applied to systems containing solids whose molecular weights are not well defined. Plots of log (water activity/moles water in 100g solution) against the square of the weight percent solids in the system, gave a series of straight-line segments. Slopes and intercepts were different for each concentration range where the straight line segments lie. An equation was derived based on this equation for water activity as a function of concentration. In the derivation, moisture transfer between two components and equality of the water activities of all phases at equilibrium was considered. The derived equation predicted accurately equilibrium water activities of mixtures of two solids.

Time-temperature histories and cooking times were determined for turkeys baked at 162.8°C from 4.44°C to an endpoint of 82.2°C in the thigh joint or breast. Turkeys (128) in five weight classes from 5.9 to 10.8 kg (0.9 kg increments) were equally divided into fresh, frozen, stuffed, unstuffed, and cooked shielded or unsheilded groups. The slowest heating point was either the wing joint or stuffing geometric center. Cooking time for unsheilded turkeys was 155 min plus 11 min/kg, unstuffed, and 200 min plus 8.8 min/kg, stuffed. Median cooking loss was 23%. Shielding of breasts prolonged cooking time. The cooking endpoint of 82.2°C in the thigh joint provided adequate lethality against Salmonella in the slowest heating points of both stuffed and unstuffed birds.

Ultraviolet (UV)-induced chemical reactions and inactivation of microorganisms in transparent and opaque fluids are strongly dependent upon the homogenous exposure of the target species to the UV irradiation. Current UV technologies used in water disinfection and food preservation applications have limited efficacy due to suspended particles shading target species. An Ultraviolet-Shockwave Power Reactor (UV-SPR) consisting of an inner rotating rotor and a stationary quartz housing and 2 end plates was used to induce 'controlled cavitation.' Eight UV low-pressure mercury lamps spaced uniformly were installed lengthwise around the quartz housing periphery. A KI to I(3) (-)chemical dosimeter for UV was used to quantify photons received by fluid in the annular space of the SPR. UV dose (J/m(2)) increased from 97 J/m(2) at 0 rpm to over 700 J/m(2) for SPR speeds above 2400 rpm. Inactivation of E. coli 25922 in apple juice and skim milk in the UV-SPR at exit temperatures below 45 degrees C was greater than 4.5 and 3 logs, respectively. The UV-SPR system proved successful in increasing the mass transfer of transparent and opaque fluid to the UV irradiated surface.

Hydrodynamic cavitation is the formation of gas bubbles in a fluid due to pressure fluctuations induced by mechanical means. Various high-acid (pH[corrected]/= 4.6) fluid foods were processed in a hydrodynamic cavitation reactor to determine if commercial sterility can be achieved at reduced processing temperatures. Sporicidal properties of the process were also tested on a low-acid (pH[corrected] 4.6) fluid food. Fluid foods were pumped under pressure into a hydrodynamic cavitation reactor and subjected to 2 rotor speeds and flow rates to achieve 2 designated exit temperatures. Thermal inactivation kinetics were used to determine heat-induced lethality for all organisms. Calcium-fortified apple juice processed at 3000 and 3600 rpm rotor speeds on the reactor went through a transient temperature change from 20 to 65.6 or 76.7 degrees C and the total process lethality exceeded 5-log reduction of Lactobacillus plantarum and Lactobacillus sakei cells, and Zygosaccharomyces bailii cells and ascospores. Tomato juice inoculated with Bacillus coagulans spores and processed at 3000 and 3600 rpm rotor speeds endured a transient temperature from 37.8 to 93.3 or 104.4 degrees C with viable CFU reductions of 0.88 and 3.10 log cycles, respectively. Skim milk inoculated with Clostridium sporogenes putrefactive anaerobe 3679 spores and processed at 3000 or 3600 rpm rotor speeds endured a transient temperature from 48.9 to 104.4 or 115.6 degrees C with CFU reductions of 0.69 and 2.84 log cycles, respectively. Utilizing hydrodynamic cavitation to obtain minimally processed pasteurized low-acid and commercially sterilized high-acid fluid foods is possible with appropriate process considerations for different products.

A W20mutant strain derived from Bacillus subtilis H1using UV radiation and exposure to a mutagenic agent was used for α-amylase synthesis. Both cultures were characterized for growth and continuous α-amylase syntheses, and the isolated enzymes had the same molecular mass of ∼55 kDa. W20cells, harvested from specific growth phase, were immobilized within alumina beads and placed in a bioreactor column; specific feedstock (FS) was used for α-amylase syntheses and was affected by its composition, and its flow rate as well as temperature. Maximal α-amylase productivity (427-µM reducing sugar[s]/mL effluent/h) was achieved using stationary-phase cells and FS containing 3% starch kept at 45C and 100-mL/h flow rate. When FS, with 2% starch, was fed to the column at the same temperature but at a higher flow rate, productivities were reduced to 326 µM. α-amylase synthesis by W20cells was affected by growth phase of cells used, column temperature and FS flow rate. Some immobilized cells were washed out from the column because of shear forces on bead surfaces by FS flow rate and by temperature. Scanning electron micrographs revealed large numbers of cells attached to external and internal bead channels. This article is a novel approach for α-amylase synthesis and can be used for its industrial production.

Pulsed nuclear magnetic resonance was used to monitor the thermophysical transition of aqueous egg albumin dispersion. Gelling, which was manifested by an increase in force required to penetrate the surface of the dispersion, was accompanied by a decrease in T1, the spin-lattice relaxation time of water protons in the dispersion. There was a high, negative correlation coefficient between gel strength and T1. Apparent rate kinetics of the transition was fist order for changes in T1 and zero order for changes in gel strength, with activation energies for the rate constants of 42.62 and 43.68 kcal/mole, respectively.

The minimum inhibitory concentrations (MIC) of 9 liquid smoke fractions against pathogenic and food spoilage organisms were determined using broth or agar dilution methods. Extract F1 (highest carbonyl content and lowest pH) was most effective against all microorganisms. MIC of F1 was 0.75% against Lactobacil-lus plantarum; 1.5% against Listeria innocua M1, Salmonella, Escherichia coli 8677, Saccharomyces cerevisiae, and Aspergillus niger; and 2% against Pseudomonas putida. The least effective smoke fraction F9 had MIC >9% against most organisms tested, had high pH, low phenols, and low carbonyls. Growth curves of individual bacteria and yeast below the MIC exhibited a prolonged lag phase that increased with increasing smoke concentrations.

Three cultures immobilized by entrapping within alginate gel beads and packed in near-horizontal acrylic columns (15.0° angle) were used for alcohol/malolactic fermentation of grape must. Immobilized cells of Saccharomyces cerevisiae spp. chablis were placed in the 1st column, S. cerevisiae cells (an alcohol-sucrose-tolerant yeast) in the 2nd and the Lactobacillus delbrueckii cells in the 3rd column. Grape must with different levels of sugar(s), were each fed to the bioreactor columns at dilution rate of 0.74 h−1 and recycled at 37.0C. The percent fermentation efficiency and yield using the 1st and 2nd columns for grape must containing 33.3% sugar(s) were 92.9 and 91.5%, respectively, and the wine had 15.5% alcohol after 23 cycles (∼ 50 h fermentation). The viability of the immobilized yeast cells in the alginate gel-bead was 84%± 4.0. Immobilized Lactobacillus delbrueckii cells were then added to the 3rd column (in series 37.0C) and the three cultures resulted in alcohol/malolactic fermentation of the grape must, evidenced by the high level of alcohol formed and simultaneous transformation of malic to lactic acid. Sensory evaluation of the wine scored high (7.8 ± 2.0 based on a value of 10.0) and indicated the potential of using multiple immobilized cells of two specific yeast cultures and a malolactic Lactobacillus for wine production.

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 1 H NMR. Spin-lattice (T 1 ) values ranged from 588 to 642 ms, with highest values seen for phosphate-treated samples. Increases with treatment were attributed to changes in moisture. Cooking reduced T 1 values due to loss of moisture and setting of the protein gel. Compression produced further reductions in T 1 values. Little dispersion in R 2 with pulse spacing (T) was observed for uncooked samples.

Nine cultures were examined for growth at 37C in media with different levels of PCB and selected one culture to treat an industrial liquid waste containing high levels of PCB 1248. All the nine cultures grew well in the presence of 100 to 500 μg PCB 1254 mL−1 glucose basal salt broth (GBSB) as well as in tryptic soy broth (TSP) with no significant changes in generation time. The cultures grew well in basal salt agar containing PCB as sole source of carbon. Pseudomonas aeruginosa and Serratia liquefaciens strains survived for 75 to 120 min in the presence of 300 to 2000 μg PCB 1254 mL−1 sodium-phosphate buffer (SPB) pH 7.0. The P. aeruginosa cells removed both PCB 1254 and 14C-PCB from SPB and GBSB within 48 h and the percent uptakes were 26 and 39.7%, respectively. The results of the fate and distribution of PCB 1254, including 14C-PCB, in cells of P. aeruginosa, S. liquefaciens, and two Bacillus strains grown in PCB-media showed that more than 50% of the 14C-PCB were in the alcohol and in alcohol-ether soluble fractions (mostly lipids). This was also confirmed after rupturing the P. aeruginosa cells using French pressure and/or lysozyme and fractionation. Both the intrinsic flora and P. aeruginosa strain were used in a bioreactor system for the treatments of 27 and 33 gallons industrial liquid waste containing 150 and/or 800 mg PCB 12481 1−1, respectively, and complete oxidation was achieved, within approximately 150 days and the biological half-life of the PCB was 30 and 15 days, respectively.

Fresh split chicken breasts were injected with 5% sodium acid pyrophosphate (SAPP), 5% sodium tripolyphosphate (STPP), 2.5% Genu pectin (GENU), or the combination of 5% SAPP with 2.5% GENU and 5% STPP with 2.5% GENU. Calcium lactate (0.1 M) solution was sprayed on the surface of chicken marinated in pectin. Marinated samples were stored at 4C for 7 days to evaluate changes in the psychrotrophic bacterial count and quality. STPP injected chicken breast had highest (α=0.05) marinade pickup, net weight increase, cook yield and moisture content. SAPP injected chicken had intermediate marinade pickup, but lowest retention in the muscle among all treatments. Marinades with pectin or pectin combined with phosphate had lower pickup but higher marinade retention compared with SAPP injected breasts. The water holding capacity (WHC) of STPP and GENU injected cooked chicken breast was higher than SAPP injected samples or control. All marinated chicken breasts had significantly lower shear force than noninjected control. Neither phosphate nor pectin had a significant influence on microbial activity of marinated chicken.

The effect of time of cut-up and needle injection of phosphate marinades into poultry was evaluated. Poultry were collected after the chiller, cut and needle injected immediately with phosphate containing marinade or needle injected after 5 h. Whole birds were aged 5 h before cut-up and needle injection as a control. The percentage weight gain and the percentage net weight increase was less for poultry which was cut or needle injected without aging, but varied depending on marinade composition. Cook yield was not affected by time of cut-up or needle injection of marinade. No differences in tenderness and juiciness between treatments were detected by untrained or trained panelists (p < 0.05).

We investigated the effects of total process lethality on the decomposition of hydrogen peroxide, presumably due to catalase activity. Ground chicken breast meat was heated to various end-point temperatures (EPTs) in 10 heating treatments varying heating time and rate. Within each treatment, residual catalase activity was affected by the product EPT. However, samples heated to the same EPT under different treatments retained less enzymatic activity as heating time increased. Total process lethality was calculated to assess the severity of heating at each EPT under each heating condition. Residual enzymatic activity was directly related to the total lethality.

Vapor induced puffing during high temperature fluidized bed (HTFB) dehydration of apple cubes was optimized using response surface methodology (RSM). Osmoblanching in sugar syrup prevented enzymatic browning. Successful puffing was achieved by creating a surface barrier to vapor by dipping the cubes in starch solution and manipulating the temperature and time of exposure in the HTFB. Optimum conditions for minimum bulk density with acceptable levels of nonenzymatic browning included dipping osmoblanched apple cubes in 1% starch solution, followed by HTFB drying 11 min at 157 o C. Product bulk density exhibited a minimum' while nonenzymatic browning values did not display an optimum. Minimum value of bulk density predicted by RSM and browning values were very close to those verified experimentally for product processed under the identified optimum conditions

Thermal conductivity of carrots and potatoes was measured using a line heat source probe adapted for measurements to 130 o C. Fastest response and rapid attainment of linearity in temperature rise vs ln time plots, were obtained with a silicone oil-filled probe with an uninsulated thermocouple junction. Custom designed electronics to amplify thermocouple output, and computer control of measurements, data acquisition and analysis resulted in 0.4% data repeatability (two standard deviations) for calibration standards. Thermal conductivity of carrot and potato vs temperature agreed well with the published volume fraction model for multi-component foods

Trichoderma reesei (QM 9414) produced cellulase in continuous culture, on media containing xylose (1%) supplemented with sorbose (0.3%) to induce cellulase production. Maximum cell mass of 4.54 kg/m(3) occurred at pH 4.0 and a dilution rate of 0.0391 h(-1) where residual substrate was 0.43 kg/m(3), but no cellulase was produced. Maximum cellulase production of 0.69 FPU occurred at pH 3.5 and a dilution rate of 0.0110 h(-1), where cell mass production was 2.56 kg/m(3) and residual substrate was 0.15 kg/m(3). Monod kinetic constants, corrected for endogenous metabolism, were 0.091 h(-1), 0.469 kg/m(3), 0.00923 h(-1), and 0.470 kg cells/kg xylose at pH 3.5, for the maximum specific growth rate, Michaelis-Menten coefficient, endogenous metabolism coefficient, and yield coefficient, respectively. Specific growth rate fitted a maturation time model, which predicted decreasing maturation time with increasing pH.

Vacuum infiltration of Majestic peaches (Prunus persica) for 1 hr with a solution of Marsh grapefruit pectinmethylesterase (PME) containing 100 mg/L CaCl2 significantly increased firmness of canned peaches. Mean firmness of peaches infused 2 hr and thermally processed was 13.9 J/Kg as compared to 3.2 J/kg for noninfused, processed controls. The calcium content increased from 278 to 432 mg/kg during 2 hr infusion of blanched peaches. Specific activity of PME in peach halves increased more than 20 fold after infusion.

Carrot dices were heated under ultra-high temperature sterilization conditions in a packed bed to quantify the effect of superficial fluid velocities on heat transfer coefficient (h) and obtain a value for thermal diffusivity (α). h and α were determined simultaneously under non-constant heating fluid temperatures using a finite difference technique. Temperature profiles calculated using assumed h and α were matched with measured temperature at two points in a cube. Using best fit value for α of 1.94 × 10−7 m2/sec, mean h ranged from 600 to 1533 and 359 to 735 W/m2K for 0 and 1.58 cm/sec fluid velocity and 1 and 2 cm cubes, respectively. At 15.2 cm/sec, when a controlled heat transfer, calculated α was 1.86 ± 0.044 × 10−7 m2/sec.

Puffed volume and puling uniformity of a fat-free snack were investigated. Strips of drum-dried sweet potato-tapioca pastes were puffed 15 sec at 200 o C in a fluidized bed. Puffed product specific volume (SV) was related to starch gelatinization, soluble solids content, initial moisture and method of half-product preparation. SV was maximum (490% increase) and most uniform (3.94% coef. of variation) when 70% moisture paste was drum-dried at 100 o C and 1 rpm to produce the half-product. Starch was 93% gelatinized in this process. Soluble solids reduced puffing by reducing starch gelatinization. Half-product produced by sheeting dough containing pregelatinized starch had puffed volumes which significantly correlated with starch gelatinization

Degree of gelatinization (DG) of starch in dry products was measured from the amount which dissolved in 0.2N KOH. The dissolved starch was complexed with O.1N iodine and quantitated from absorption at 600 nm. When pregelatinized starch in KOH was the basis for the standard curve only 94% of added gelatinized starch mixed with raw starch was recovered. Recovery was 100% and coefficient of variation was

The process requirements and properties of dehydrated squid protein prepared by a water extraction and spray dehydration process were studied. After removal of skin and viscera, a water soluble fraction was obtained by filtering the comminuted slurry which, when diluted and spray dried, was converted into a powder having a very light color. A low yield of 29.4% on the semi-pilot scale appeared to be due to material loss during washing. In a well designed laboratory study however, yield averaged 74% indicating that loss during washing could be minimized. The product averaged 81% protein, had excellent water solubility and a good oil binding capacity as well as emulsion stability. Animal feeding studies showed that nutritionally the quality of the dehydrated squid protein is comparable with that of casein.

Techniques for measuring changes in physical properties of meat batters during heating that would be suitable for studying kinetics of gelation were studied. Change in absolute modulus as measured by a dynamic tester was too variable to be useful in studying gelation kinetics. However, differences in consistency show up as significant differences if the absolute moduli of the raw batters. Increase in volume during heating was strictly a temperature effect and the rate of expansion at the same heating medium temperature was the same for a bitter that was gelling compared to a gelled batter in the same mold. Pressure change on heating of a batter at constant volume showed a pattern consistent with expected behavior of proteins on heating. Plots of pressure against temperature were a series of linear sections with the transition points occurring at 33–36°C and at 57–67°C. These temperature ranges are known to start insolubilization of muscle proteins and start solubilizaation of collagen respectively. Plots of unaccomplished pressure change against time on semi logarithmic coordinates was used to calculate a time constant for each stage of the process thereby giving a measure of the rate of gelation.

Metmyoglobin (Mb+) reduction was studied in ground beef, beef slurries and extracts held in air, nitrogen or CO-air mixtures. Significant Mb+ reduction occurred in aerobic extracts but not in ground beef or slurries in the presence of ferricyanide. A nonenzymatic electron trans. fer was demonstrated in extracts under these conditions. At normal meat pH (5.6), carbon monoxide (CO) accelerated Mb+ reduction, even in the presence of air, with the rate of reduction dependent upon CO concentration. Neither the addition of catalase nor compounds that inhibit the electron transport chain markedly affected Mb+ reduction under a CO atmosphere while arsenate addition slightly accelerated the reaction. The use of ferricyanide as the pigment oxidant increased the Mb+ reduction rate in aerobic extracts and in all systems under CO, but was not necessary to observe reduction under CO. Possible mechanisms for the CO-enhanced reduction of Mb+ are explored.

The effect of temperature and smoking schedules on the quality of Spanish mackerel was evaluated using a pilot plant model of a commercial smokehouse system. Although the final moisture contents of the products are the same, the product smoked only at high temperature (160°F) had the softest texture. Smoking only at low temperature (100°F) did not develop surface color thus resulting in a product having the poorest appearance. A process which combined smoking at both low and high temperature at 60% RH gave a product having excellent texture and appearance. High temperature smoking above 160°F darkened the surface excessively and reduced product acceptability. A holding period after brining and between the cold and hot smoking stages in the process improved appearance and smoke flavor. Water phase salt content judged to be the optimum saltiness was 3.7%. Microbiological counts in the product of the combination cold and hot smoking process were very low (< 10/g). Smoking at 90–100°F did not allow an increase in surface microbiological count. The final step in the process when carried out at 160°F inactivated most of the vegetative microorganisms inoculated on the surface. Storage life of Spanish mackerel produced by cold followed by hot smoking (160°F) was 45 days at 38°F and at least 22 wk at 10°F. This process does not meet the 30 min at 180°F minimum temperature requirement in the Good Manufacturing Practice Regulation of the Food and Drug Administration for smoked fish; therefore, frozen storage and distribution are recommended.

A process for heating smoked fish was developed such that the lethality of the heating process is equivalent to a 12 decimal reduction of spores of Clostridium botulinum Type E. This lethality is similar to the specifications in the Food & Drug Administration smoked fish Good Manufacturing Practice regulations. The requirements for a fish smoking oven that would be necessary to carry out the process were also determined. The staged temperature process, which started at 160°F (71.1°C) dry bulb and 140°F (60°C) wet bulb, with wet and dry bulb temperatures increases of 10°F (5.6°C) in 10 min increments until the internal temperature of the fish reached 194°F (90°(Z), minimized undesirable defects in the smoked fish product when compared with other smoking (process) schedules. The energy consumption of the recirculating air oven, for the high temperature staged process (186.482 MJ) was found to be twice that for a constant temperature 71.1°C process (92.337 MJ) with most of the energy used attributed to the generation of steam used for humidification, and heat losses through the un insulated ductwork. A heat balance on an oven with steam humidification and a heating element capacity of 35.5 kW showed that only 45.5 kg of product can be processed effectively using the staged temperature process.

Rabbiteye blueberries were dried using an experimental high temperature fluidized bed (HTFB) dehydrator and the properties of the dried product were evaluated. 15 m/sec air velocity was required for fluidization and at 170°C the moisture content (MC in kg water/kg dry matter) of thawed blueberries was reduced from 5.8 to 0.7 after 8 min. After osmotic dehydration in sucrose, MC was 1.3, and 4 min in the HTFB drier at 150°C reduced MC to 0.28. Reduction of water activity to 0.5 after HTFB required cabinet drying at 60°C and 4 m/ set for 2.13 and 2.75 hr for the untreated and osmotically dehydrated berries, respectively. HTFB simultaneously dried and puffed the berries, resulting in reduced bulk density compared to berries produced using conventional drying. Osmotic dehydration prior to HTFB imparted a raisin-like texture to the product.

The heat transfer coefficients (h) between a cube and water were 239 and 303 W/m2K at 0 and 0.86 cm/s relative velocity. In 35% sucrose and 0 cm/sec, h was 146 W/m2K. A model for heat lethality in cubes during continuous sterilization which used finite difference equations for heat conduction and above values of h, revealed that hold times for 6D inactivation of PA 3679 (F0= 7.2 min) in an isothermal fluid at 132.2°C were 1.78 and 5.2 min for 1 and 2 cm cubes when h was 303 W/m2K and 1.23 and 4.13 min when h was 2500 or higher. When h was 239 W/m2K, hold times were 2.36 and 6.02 min for 1 and 2 cm cubes. When fluid entered the hold tube at 132.2°C and particle to fluid ratio was 0.56, fluid-particle heat exchange increased hold time to 12.2 and 119 min for 1 and 2 cm cubes.

Environmental conditions (temperature, humidity and air velocity) were monitored inside refrigerated trailers loaded with beef carcasses during stationary and in-transit trials. The effects on meat color maintenance were followed on meat samples located throughout the trucks. The effect of initial carcass heat load on color maintenance during transport was studied utilizing a simulated trailer environment. Results show that an excellent environment is maintained in refrigerated trailers for beef color maintenance in-transit despite fluctuations in outside temperature and over-the-road conditions. Results from tests in which carcasses with elevated internal round temperature (15°C) were held in a simulated trailer environment suggests that shipping of such carcasses in refrigerated trailers could lead to bacterial growth and discoloration in-transit.

Fish sausage from minced Spanish mackerel was formulated to aw of 097–0.92 using egg white solids alone and in combination with nonfat dry milk, alginate and soy protein isolate, without and with nitrite added at 150 ppm. The batter was inoculated with PA 3679 spores at ca. 105/g, chopped, stuffed in casing, cooked to a core temperature of 85°C, vacuum-packaged and stored at 25°C for 60 days. The test organism did not reproduce in formulations having aw 0.95 spoiled. Product stability was influenced by aw regardless of binder type and presence of nitrite.

The shelf life and quality of mullet (Mugil spp.) caught off the Southeast Atlantic coast were evaluated during storage at subzero temperature (-2°C) either unpackaged or vacuum packed in iolon film. Subzero temperature was maintained by storing fish in either 2% NaCl- or 7% propylene glycol-ice. Shelf life of fish stored in -2°C ice was 10 days, compared to 7 days for the fish stored in 0°C ice. Extension of shelf life was attributed to delayed microbial growth and slow biochemical changes. Structural changes due to ice crystals at subzero temperature storage appeared to be minor compared to those which occurred during freezing at -20°C as revealed by microscopic examination. The minor structural changes along with insignificant biochemical changes resulted in products having acceptable eating quality for 10 days.

Deterioration of mechanically separated fish flesh as measured by extent of lipid oxidation and color change was studied using fresh mullet (Mugil spp.). The parameters studied included contact with iron surfaces, mechanical stress applied to the muscle during deboning, temperature of deboning drum, washing of deboned fish flesh, and postdeboning treatments including addition of antibiotic, sparging with nitrogen gas, cooking, freezing and thawing. TBA value was used as an index of lipid oxidation and the reflectance ratio of metmyoglobin to oxymyoglobin as an index of color change was determined using reflectance spectrophotometry. The degree of stress applied during deboning did not cause any significant variations in TBA value, whereas increased temperature of the deboning drum showed an adverse effect which became significant with prolonged storage. Contact of flesh with iron parts of the deboner resulted in a pronounced increase in TBA value of the flesh within the short span of time involved in the deboning process. Washing improved significantly product quality when the product was frozen for an extended period, but appeared to have no major advantage when stored under refrigeration and immediately processed. A marked rise in TBA value occurred during thawing with the effect being more pronounced with increased thawing time. The effect of thawing also became more pronounced with extended frozen storage. Ambient oxygen and microbial activity appear to have an insignificant role in lipid oxidation during storage. The lateral tissue (red muscle), tissue along the visceral cavity, and bone marrow exudate appeared to be the most susceptible to the development of oxidative rancidity. Rate of TBA value change was very rapid when these muscles had contact with iron surfaces.

Various protein preparations suitable for use as processed meat additives were evaluated for their physical properties that could be related to their functional properties in comminuted meat products. Each of the protein preparations were evaluated for: water absorption capacity at various temperatures, solubility at various temperatures, viscosity of suspensions of varying solids contents and gelling ability. Whey protein concentrate, peanut flour, single cell protein, and low temperature extracted chicken meat protein were added to a luncheon loaf formulation made with lean pork and pork back fat and the effect of the addition on the magnitude and direction of changes in the textural characteristics and fat and water binding were evaluated at various exchange levels of the protein. Correlations were made between the measured physical properties and protein performance in the test system. The properties of the test system with additives that were evaluated included: magnitude of fat and water released on cooking, compressive strength, and Warner Bratzler shear force of the cooked samples. Significant correlation coefficients were found between solubility at any temperature from 4.5–72°C and fat binding, solubility at 100°C and the textural mechanical properties, and water absorption capacity at 90°C and water binding. The more soluble proteins allowed more fat release on cooking, and the cooked products had lower indices for mechanical strength. The pattern of solubility change with temperature was a better index of performance, rather than solubility at a single temperature.

The texture profile of frankfurter-type products prepared from minced Spanish mackerel (Scomberomorus maculatus) was evaluated. Twelve character notes were identified: springiness, hardness, cohesiveness, moisture release, crumbliness, coarseness, graininess, juiciness, adhesiveness, lumpiness, chewiness, and mouthfeel-oiliness. Overall texture acceptability was also evaluated. Differences in juiciness and mouthfeel-oiliness were not detected. Springiness, hardness, cohesiveness, and lumpiness had the highest correlation with the overall texture acceptability. Products with 10% soy protein fiber (SPF) were better accepted than those having 20% or no SPF. Egg white (to 20%) improved the texture; however, its flavor was detectable when 10% or more was added. The most acceptable texture was exhibited by products containing 5–10% ground drumdried fish.

The extent of protein-protein interactions in actomyosin solutions was measured as a change in light scattering absorbance of a solution undergoing change. The extent of the reaction registered as an increase in light scattering absorbance indicating an increase in the size of the macromolecules. In treatments where the extent of protein-protein interaction was extensive, film formation and/or precipitation of the macromolecules occurred. At constant protein concentration the kinetics of the reaction was dependent upon temperature, pH and the type of actomyosin used. In general, the rate and maximum extent of change increased with increasing temperatures and decreasing pH. Below 40° C more change was generally observed in beef actomyosin solution compared to mackerel at the same temperature and pH. However, at higher temperatures, mackerel actomyosin often shows more change than beef under the same conditions. The shapes of the reaction curves were such that the slope of the steepest line that can be drawn from the origin to tangent the curve at the region where the change starts to taper off (the characteristic slope), was a good index of the rate of change and the maximum extent of interaction attained. Arrhenius-type plots of the characteristic slopes showed three possible mechanisms of change predominating within certain temperature ranges, as indicated by well-defined inflections in the curves, reflecting varying activation energies for the reactions. The three temperature zones are: below 40°C; between 40 and 60° C; and above 60° C. Below 40° C the rate and maximum extent of protein-protein interaction is very strongly temperature dependent.

Factors affecting textural characteristics of cooked comminuted fish muscle were investigated. These factors included: time of comminution, presence of NaCl or NaCl and polyphosphates, effect of mechanical deboning, temperature of cooking, and type of heating medium used. Textural characteristics were evaluated objectively using as an index: compressive strength, modulus of elasticity, resilience, and shear strength. The change in the physical state of the protein-water system was determined from the quantity of fluid (expressible fluid) that can be expressed from the specimen subjected to a fixed compression force. With extensive chopping, mechanical strength diminished as the concentration of extractable myosin in the muscle homogenates decreased. Changes in expressible fluid followed changes in physical properties. Formulations with higher moisture contents were more susceptible to adverse changes brought about by mechanical treatments such as chopping. Mechanical strength of the cooked comminuted muscle progressed in the order of increasing strength as follows: no additives, with NaCl, with NaCl and polyphosphates. The presence of polyphosphates allowed increased solubilization of muscle protein and improved water binding. The variation in textural strength of products receiving different preheating treatments appeared to be related to the changes in water binding as shown by the inverse relationship of mechanical strength to the quantity expressible fluid. The textural strength of cooked muscle homogenates decreased in the order of: steamed, water cooked, and smoke-house cooked.

The type of sugar in the heating and recovery media affected the rate of inactivation and repair capability of a Chablis strain of Saccharomyces cerevisiae. The rate of heat inactivation decreased with decreasing aw in glucose and fructose but not in sucrose solutions. At any aw the order of susceptibility to inactivation of yeast cells was consistently: fructose, glucose, and sucrose. In fructose, a major proportion of the survivors exhibited sublethal injury. When suspended in solutions containing the various sugars after heating and incubated for up to 18 hr prior to plating, the type of sugar in the solution influenced the ability of cells to repair injury.

The effect of temperature and time in a fluidized bed dryer, the concentration of biopolymcr treatment and blanching time on quality attributes of dehydrated carrots was evaluated by response surface methodology. Optimization maximized rehydration ratio and minimized bulk density and carotene loss. Based on surface responses and contour plots, optimum conditions were: drying temperature of 150oC, exposure time of 12.5 minutes, biopolymer concentration of 1.40%, and blanching time of 12 minutes. Experimentally determined values for rehydration ratio, bulk density, and carotene loss in product processed under the optimum conditions were very close to the predicted values of 9.5, 0.05, and 15.7%, respectively.