Steam Surface Pasteurization of Beef Frankfurters

Meat and poultry products are sources of foodborne bacterial contamination. We used flash steam heating followed by evaporative cooling to quickly reduce bacterial contamination on the surface of beef frankfurters without degrading appearance. The rate of heat transfer was studied by measuring surface temperature in a pressure chamber during steam heating. Quality changes were determined by measuring color and weight as functions of steam temperature and treatment time. Efficacy of the process was verified by microbiological experiments using L. innocua. Treatment times of 30–40 set at 115–136°C gave a 4 log reduction in bacterial counts on the surface without severely affecting color or weight. After long-term storage at 6°C and at 19°C, levels of bacteria on inoculated frankfurters remained reduced and there was no difference between treated and untreated products in color or weight.     

Tracer Diffusion and Electrical Conductivity in Sodium-Rubidium Silicon Sulfide Glasses

The tracer diffusion coefficients of ²²Na and ⁸⁶Rb and electrical conductivity were measured in a series of 0.56(Na, Rb)₂S.0.44SiS₂ glasses as a function of the Rb/Na ratio and temperature. The data were used to calculate the Haven ratio as a function of the Rb/Na ratio. The Haven ratio at 149.6°C increases from ∼0.3 in single-alkali glasses to ∼0.80 for intermediate compositions. The results are consistent with a single jump mechanism involving jumps of alkali ions between unoccupied sites. The observed correlation effects arise through interactions between alkali ions and charge-compensating centers in the glass network. The charge-compensating centers are thought to correspond to non-bridging oxygen ions in some oxide glasses and to nonbridging sulfur ions in sodium-rubidium silicon sulfide glasses.     

SCALE‐UP and FIELD TEST of the VACUUM/STEAM/VACUUM SURFACE INTERVENTION PROCESS FOR POULTRY1

The Vacuum/Steam/Vacuum surface intervention pilot plant processor was scaled up to a mobile unit that can be transported to close proximity of chicken processing plants. After several modifications to the mandrel that supports the broiler carcass in the treatment chamber to minimize mechanical damage, the unit was capable of 1.1 log cfu/mL kill of inoculated Listeria innocua and 1.4 log cfu/mL kill of inoculated E. coli K‐12. Field tests achieved 1.4 log kill of E. coli and 1.2 log kill of Campylobacter on freshly processed chicken using 3 cycles and 138C saturated steam. But, there was extensive mechanical damage. the mandrel was modified in the Eastern Regional Research Center pilot plant to eliminate the mechanical damage. With mechanical damage eliminated, the bacteria kill was 1.1–1.5 log of inoculated E. coli K‐12 with a total process time of 1.1 s.     

ROTOR RESISTANCE ESTIMATION FOR SLIP ADAPTATION IN SENSORLESS INDUCTION MACHINE DRIVES

ABSTRACT

This work presents a rotor resistance estimation algorithm. The estimation process is based on a recursive least squares method. It is applied to a speed sensorless induction motor drive scheme in order to implement slip adaptation. A discrete approach is considered in which an induction motor model written in form of difference equations is used by the estimation algorithm. All the associated mathematical developments are shown. Simulation results are used to verify the performance of the proposed rotor resistance estimator.     

Dehydrated Blueberries by the Continuous Explosion-Puffing Process

A blueberry dehydration process which includes the unique continuous explosion-puffing system (CEPS) is described. A drying study including alternate drying pretreatments failed to increase the dehydration rate. It was found that care during processing was necessary to prevent rupture of the berries as rupture caused bleeding during drying which reduced the drying rate. Optimum operating conditions for CEPS were established for blueberries. Measurements of dried blueberry properties such as bulk density, color, rehydration, and disintegration were used to determine optimum operating conditions for pressure (103 kPa), temperature (190°C), and feed moisture (18.5%) for CEPS.     

Control design based on a linear state function observer

A control design method based on a linear state function observer is proposed. The method is a semi-inverse design procedure in that the control law is not designed before the observer system, but is a result of the observer design. However, the observer design is not completely independent of the control design, but seeks to yield a feedback signal that is close to a prescribed control law. First, the observer design problem is considered as the reconstruction of a linear function of the state vector. The linear state function to be reconstructed is the given control law. Then, based on the derivation for linear state function observers, the observer design is formulated as a parameter optimization problem. The optimization objective is to generate a matrix that is close to the given feedback gain matrix. Based on that matrix, the form of the observer and a new control law can be determined. The semi-inverse design procedure can yield a reduced-order observer with dimension considerably smaller than that of the system. Two numerical examples are used to demonstrate the proposed design procedure.     

FREE CONVECTIVE DRAFT INDUCED BY THERMAL AND CONCENTRATION GRADIENTS INSIDE AN ISOTHERMAL,VERTICAL CYLINDER†

Laminar, free convective flow through a vertical cylinder induced by the thermal and concentration buoyancy forces is investigated. The numerical studies involve development of a steady-state, two-dimensional heat and mass transfer model for the moist air core of the vertical tube. The stream function-vorticity method is employed to simplify the governing, coupled conservation equations which were then numerically solved by the successive over-relaxation (SOR) and alternating direction implicit ((ADI) methods.

A graphical correlation was found between dimensionless flow rate and dimensionless tube length as a function of the buoyancy force ratio N = Gr/Grc. Excellent agreement was obtained for the dimensionless flow rale results with those of Davis and Perona¹⁶ and Kageyama and Izumi¹³ for the case when only the-thermal buoyancy force is considered.

The combined buoyancy force from thermal and species diffusion provides larger local Nusselt Nu and local Sherwood Sh numbers relative to the case when just one buoyancy force is accounted for. Both local Nu and local Sh are seen to asymptotically approach a constant value as flow develops.     

Effects of Dithiocarbamate Fungicides on Corrosion Mechanisms and Shelf-Life Behavior of Light Acid Fruits in Plain Tin Containers

From the results of monitoring commercial test packs, synthetic test packs, and related laboratory experiments, the effects of dithiocarbamate fungicide residues on the shelf-life of canned acid fruits in plain tin containers have been clearly demonstrated. It has been shown that the sulfur compounds resulting from the decomposition of the fungicides are the “active” species and, depending on the quantity of fungicide initially present, can control corrosive failure through pitting corrosion mechanisms. Steel chemistry has also been shown to be an important factor in these interactions as evidenced by the superior performance of aluminum deoxidized continuous cast containers when compared to containers produced from type L ingot steel.     

Bioassay Analysis of Dry-Cured Ham Processed to Affect Trichinella spiralis

Effects of curing time and temperature to destroy Trichinella spiralis in dry-cured hams were evaluated. Five muscle groups from small, medium and large, short-cure hams and large, bag-cure hams were subjected to a digestion technique to determine the number of spiralis larvae. Trichinae in small hams held at 10°C for 90 days, in medium hams at 23.9 and 32.2°C for 35 and 11 days, and in large hams at 10 and 23.9°C for 90 and 35 days, respectively, were rendered non-infective. Medium hams contained a number of trichinae after 90 days at 10°C. Bag-cure hams aged at 23.9°C for 35 days were free of trichinae. Results could indicate insufficient aging time at 10°C for medium hams and the need for reviewing current USDA-FSIS regulations for the destruction of T. spiralis.     

EFFECTS OF GROWTH REGULATORS ON YIELD AND QUALITY OF MUNGBEAN SPROUTS GROWN IN AN AUTOMATICALLY CONTROLLED CHAMBER

High quality mungbean sprouts are characterized by thick hypocotyls and short roots. In this study, three plant growth regulators (gibberellic acid, ethephon and abscisic acid) were applied to mungbean sprouts during growth in a microprocessor controlled chamber. Ethephon and gibberellic acid treatments produced sprouts having substantially more food value (dry matter, protein, ascorbic acid) per 100 g of mungbeans than the nontreated controls. Single application (10 or 20 ppm) or double application (20 ppm) ethephon treatment improved mungbean sprout quality through its root-shortening and hypocotylthickening effects. The chamber developed in this study eliminated labor and provided a simple, convenient and reproducible sprout growing process. It has potential in small factories or restaurants as well as in the laboratory.