A COMPUTER-THERMOCOUPLE INTERFACING SYS FOR TIME-TEMPERATURE DATA COLLECTION FROM THERMAL FOOD PROCESSES1

A data logger that uses two computers simultaneously for collection and immediate observation of thermal food process data is described. Limits of error for a single observation, determined using a standard voltage input, was found to be less than .17° F (.094 °C). Component drift was found to be .04° F (.022° C) per hour. When properly calibrated, the system can be used for accurate data collection in most thermal process evaluations.     

APPARENT THERMAL CONDUCTIVITY,WATER CONTENT,DENSITY, AND POROSITY OF THERMALLY-PROCESSED GROUND CHICKEN PATTIES1

Changes in thermal conductivity, density, and porosity during heating were evaluated for commercially manufactured ground chicken breast patties in a temperature range of 23 to 85C. The thermal conductivity of the meat, heated in a closed container, decreased approximately 8% with increasing temperature. In a separate test series, where water was free to leave the meat during cooking, the water content decreased approximately 15% over the same temperature range. The thermal conductivity of the meat was modeled as a quadratic function of temperature. Changes in the water content were modeled as a linear function of temperature. The solid density increased approximately 6%, and the porosity more than doubled with a temperature increase from 23 to 85C.     

NMR IMAGING, CALORIMETRIC, and MATHEMATICAL MODELING STUDIES of FOOD FREEZING

Nuclear magnetic resonance imaging (MRI), calorimetry, and temperature measurements were used to monitor cylindrical potato sections frozen at -11C and -42C. MRI showed the advance of the nonsymmetric freezing zone and loss of signal intensity as liquid water turned to ice. Differential calorimetry was used to follow heat removal during transient freezing. Measured times to 95% enthalpy change were 24 min (-42C) and 49 min (-11C), as compared to modeled values of 29 min (-42C) and 100 min (-11C). Times to 95% change in the NMR signal, integrated over the area of the image, were 21 min (-42C) and 56 min (-11C). Changes in NMR signal intensity could be correlated with the amount of unfrozen water remaining after a steady-state had been reached. At -42C, NMR indicated 25% unfrozen water remaining as compared to 26% by calorimetry, and 22% by modeling. At -11C, NMR measured 67% unfrozen water remaining as compared to 48% by calorimetry, and 25% by equilibrium modeling.     

EFFECT of THERMAL PROCESSING ON THIAMINE RETENTION, IN-VITRO PROTEIN DIGESTIBILITY, ESSENTIAL AMINO ACID COMPOSITION, and SENSORY ATTRIBUTES of PERIWINKLE-BASED FORMULATED LOW ACID FOODS

The effect of thermal processing on thiamine retention, in vitro protein digestibility, amino acid composition, and sensory attributes ofperiwinkle-in- brine (PIB), periwinkle-in-sauce (PIS), and periwinkle-in-egusi soup (PES) with F_o- Values of 4.5, 6.4 and 7.2 mm, respectively, were investigated at pH of 5.8 and temperature range of 104- 121.1C. Thiamine losses were 55.2–7.4%, 64.9–9.7% and 68.5–10.3% for PIB, PIS and PES, respectively, within 104 - 121.1C. Heating resulted in slight decrease in protein digestibility. Methionine losses were 19.0 - 7.8%, 25.2 - 11.4% and 30.8 - 24% in PIB, PIS, and PES, respectively, within 104–121.1C. the flavor appearance and texture of the products improved with increasing temperature and shorter times for commercial sterilization.     

ELECTRICAL CONDUCTIVITY of SELECTED JUICES: INFLUENCES of TEMPERATURE,SOLIDS CONTENT,APPLIED VOLTAGE,and PARTICLE SIZE1

A device was developed to determine the electrical conductivities of foods under ohmic or conventional heating conditions. Orange and tomato juices (serum and various solids contents) were tested in the device. the electrical conductivity of juices increased with temperature and decreased with solids content. the temperature dependence of conductivity was linear, both under conventional and ohmic heating. Experiments on suspensions of carrot juice solids, and polystyrene spheres in sodium phosphate solution showed an increase in electrical conductivity of the suspension with decreasing particle size.     

SEPARATION of CHOLESTEROL FROM BUTTEROIL USING QUILLAJA SAPONINS. 1. EFFECTS of PH, CONTACT TIME and ADSORBENT

The technical feasibility of separating cholesterol from butteroil by contacting it with aqueous solutions of Quillaja saponaria saponins followed by separation of the cholesterol-saponin complex was studied. Alternative processes and controls compared were (1) Water Control (W): butteroil was contacted with pure water; (2) Reaction (R): butteroil was contacted with aqueous solution of saponins; (3) Adsorption Control (A): butteroil was contacted with water, diatomaceous earth was then added; (4) Reaction + Adsorption (R+A): diatomaceous earth was added to the Reaction medium (from 2); (5) Reaction + Washing (R+W): the aqueous phase resulting from Reaction (2) was discarded and pure water contacted with the fat. the last step in all the above processes and controls was the separation of the fat phase where cholesterol was determined. Statistical analysis indicated that the Adsorption Control did not yield any significant cholesterol reduction over the Water Control, while all other processes gave significant reduction. the order of cholesterol separation observed was R+A > R+W > R. the levels of cholesterol reduction were significantly affected by pH of quillaja solution and amount of adsorbent used; the time of contact with quillaja solution had no significant effect over the range investigated. These results indicate the technical feasibility of reducing the cholesterol levels of butteroil using food grade quillaja saponins.