SPECIFICITY OF THE FERRIC-H2SO4 REAGENT FOR ALGINATES

SUMMARY— Alginate in foods was isolated from papain digests of the samples as the insoluble calcium salt. dispersed by sodium hexametaphosphate and a 1- to 5-ml aliquot of the dispersion 50–250 μg of sodium alginate) dried at 100°C. Heating of the anhydrous sample in the presence of the ferric-H₂SO₄ reagent for 12 min at 60°C produced a pink color with maximum absorption at 490–515 mμ and maximum density after aging for 90 min at 29±1°C. Under these conditions, proteins, amino acids (except tryptophane), other carbohydrates, vitamins. food additives and incipients did not interfere. The presence of water in the medium rendered the reaction nonspecific and increasing the temperature above 60°C or heating for longer periods at lower temperatures resulted in color formation by other polyuronides, especially pectin and pectic acid. Recoveries of alginate from several products were good: Milk, 94–98%; ice cream, 93.5–98%; pasteurized process cheese spread. 92.6-95%; chocolate milk, 92.4-95%; dietetic foods, 90-97.2%.     

THE EFFECTS OF FEEDING ELEVATED LEVELS OF VITAMINS D3 AND E ON BEEF QUALITY

Yearling (12 Angus, 12 Wagyu ≥ Angus) and 2-year old heifers (12 Angus, 12 Wagyu ≥ Angus) were fed elevated levels of Vitamin D ₃ and/or Vitamin E to evaluate beef quality. Warner-Bratzler shear force (WBS) and sensory characteristics were determined on steaks from the Longissimus lumborum (LL) aged 21 days and on steaks from the Gluteus medius (GM) and Psoas major (PM) aged 7 days. Steaks were cut from all muscles, displayed for 5 days then L * value and hue angle were determined. Vitamin E supplemented heifers received the highest sensory tenderness and juiciness scores, while no differences were observed among other treatments. D ₃+ E supplemented Angus LL had higher WBS values than other treatments and breeds. Display time affected both color measures for all muscles, but especially hue angles of GM and PM. Vitamin treatment affected LL and GM color measures in yearlings to a greater extent than in 2-year olds.     

MONTE CARLO SIMULATION OF FAR INFRARED RADIATION HEAT TRANSFER: THEORETICAL APPROACH

We developed radiation heat transfer models with the combination of the Monte Carlo (MC) method and computational fluid dynamic approach and two‐dimensional heat transfer models based on the fundamental quantum physics of radiation and fluid dynamics. We investigated far infrared radiation (FIR) heating in laminar and buoyancy airflow. A simple prediction model in laminar airflow was tested with an analytical solution and commercial software (CFX 4). The adequate number of photon tracks for MC simulation was established. As for the complex designs model, the predicted results agreed well with the experimental data with root mean square error of 3.8 K. Because food safety public concerns are increasing, we applied this model to the prediction of the thermal inactivation level by coupling with the microbial kinetics model. Under buoyancy airflow condition, uniformity of FIR heating was improved by selecting adequate wall temperature and emissivity.     

Conversion of Provitamin D3 to Vitamin D3 by Monochromatic Ultraviolet Rays in Fish Dark Muscle Mince

To determine whether the photochemical conversion of provitamin D₃ is possible in fish meat, the dark muscle of skipjack was irradiated with monochromatic ultraviolet rays (peak, 305 nm; range, 280–360 nm) under various conditions of both time of exposure and strength of light. The vitamin D₃ and provitamin D₃ content were analyzed by HPLC. The vitamin D₃ content increased, and the provitamin D₃ content decreased with 20W light at a distance of 50 cm. The conversion was at a maximum 15 hr after the start of irradiation and about 20% of the provitamin D₃ changed to vitamin D₃     

QUENCHING MECHANISMS AND KINETICS OF CAROTENOIDS IN RIBOFLAVIN PHOTOSENSITIZED SINGLET OXYGEN OXIDATION OF VITAMIN D2

The oxidation of vitamin D₂ in a solution of 12% water, 88% acetone and 15 ppm ribqflavin under light or dark was studied by measuring the headspace oxygen. Ribofiavin accelerated the oxidation of vitamin D₂ by singlet oxygen under light, but did not affect vitamin D₂ oxidation under dark. Quenching mechanisms and kinetics within the range of 0–20 ppm β‐cawtene or fucoxanthin and with 0–80 ppm retinyl acetate or retinol on 15 ppm riboflavin photosensitized singlet oxygen oxidation of vitamin D₂ were also studied. The rate of singlet oxygen formation by 15 ppm riboflavin was 1.78 umole oxygen/mL headspace‐hour. The reaction rate constant of vitamin D₂ with singlet oxygen was 2.2 times 10⁷ M^?1A s^?1. The carotenoids minimized the oxidation of vitamin D₂ by quenching singlet oxygen. The total quenching rate constants of retinol, retinyl acetate, jucoxanthin and ft‐carotene were in the order of 1.22 times 10⁸, 5.98 times 10⁸, 1.78 times 10⁹ and 5.00 times 10⁹M^?1. s^?1 respectively, which suggests that as the number of double bonds of carotenoids increases, the quenching rate constant ofcarotenoid increases.     

Stability and Photochemistry of Vitamin D2 in Model System

Oxidation of vitamin D₂ in a model system of 12% water and 88% acetone in the presence of 15 ppm riboflavin under light and dark was studied by measuring the depleted headspace oxygen. Riboflavin accelerated the oxidation of vitamin D₂ by singlet oxygen under light, but did not affect the vitamin D₂ oxidation under dark. The effect of 0 and 15 ppm riboflavin on the stability of vitamin D₂ during storage at 25 and 60°C was studied by measuring the contents of vitamin D₂ during 48h. Results indicated that photosensitized singlet oxygen oxidation of vitamin D₂ under light was temperature-independent, and triplet oxygen oxidation of vitamin D₂ both under light and in the dark was temperature-dependent.     

REFINEMENT AND EXTENSION OF fn/U: g PARAMETERS FOR PROCESS CALCULATION

A digital computer program was written to refine and extend currently available f_h/U: g tables for thermal process evaluation. Some characteristics of the resulting parameters are discussed and an error-analysis is presented.     

PREPARATION AND CHARACTERIZATION OF AFLATOXIN B2a-HEMIGLUTARATE AND ITS USE FOR THE PRODUCTION OF ANTIBODY AGAINST AFLATOXIN B1

Hemisuccinate (HS) and hemiglutarate (HG) of aflatoxin B_2a (afla B_2a) were prepared by refluxing afla B_2a with the corresponding anhydride and 4-N, N-dimethylaminopyridine in tetrahydrofuran. Two epimers of the respective HS or HG which show different chromatographic behavior and physiochemical properties were isolated and characterized. Afla B_2a-HS hydrolyzes very rapidly in aqueous solution and was not used for further study. Afla B_2a-HG hydrolyzes at a much slower rate and was selected for the coupling to protein. Using the mixed anhydride method, as much as 12 moles of afla B_2a-HG were conjugated to each mole of bovine serum albumin (BSA). The antibody obtained from rabbits immunized with afla B_2a-HG BSA is most specific to afla B₁ and shows little cross reaction with afla G₁ and aflatoxicol. The lower limit for detection of afla B₁ by radioimmunoassay using this antibody is in the range of 30–50 pg per assay.     

ESTIMATION OF PARAMETERS FOR MOISTURE TRANSPORT IN FOODS1

The problem of estimation of transport parameters in food processing models is examined. A procedure is presented which consists of controlled experiments, application of theory to model the process and estimation of parameters by comparing the experimental and predicted data by the use of nonlinear optimization technique. The optimization program estimates a set of parameters in a food processing model which gives a minimum value of the sum of squares of the deviation between the observed and estimated values. The processes considered are drying, soaking and parboiiing of rice and peanut drying. Depending on the complexity of the process, the solution of the mathematical model is given in the form of analytical, finite difference or finite element approximations. The precision of transport parameters determination is also discussed.     

A METHOD FOR MEASURING THE TEXTURE OF MEAT AND THE EFFECT OF NITRITE AND SALT ADDITION ON THE TEXTURE OF CURED MEATS1

An instrumental technique was developed for measuring the texture of canned chopped ham using the 15 cm ² wire extrusion cell of the Ottawa Texture Measuring System. Its measurement efficacy was evaluated by testing enzymatically tenderized ham. This showed that the technique was sensitive to textural changes and that the level of the added enzyme affected the ham's texture exponentially. Nitrite addition to the canned chopped ham product at levels of 0-1000 ppm did not affect its texture. The level of salt used in the curing solution, however, had a marked tenderizing effect. Similarly, compression tests on wieners indicated that nitrite addition did not influence their texture. It was concluded that the characteristic texture of the two products tested cannot be attributed to nitrite addition and that other factors such as the level of salt addition to the canned chopped ham must be responsible.     

热空气在管道中的传热计算

对工程中常见的热流体(空气)在管道传输中的换热作了简要的定性和定量分析，提供了适用于工程用途的传热计算的简易数学方法。     

PRODUCTION OF CO2 AND C2H4 AFTER GAMMA IRRADIATION OF STRAWBERRY FRUIT

Strawberry fruit (Fragaria ananassa, Duch. cv ‘Kent’) were irradiated at doses from 0 to 4 kGy and stored at 10°C to verify whether irradiation at very low doses could delay postharvest ripening while causing minimal damage to the tissues. CO₂ and C₂H₄ production were used as stress indicator. Anthocyanins and titratable acidity were measured as maturity parameters. CO₂ and C₂H₄ production increased six hours after irradiation. The increase in CO₂ production was proportional to the dose of irradiation and was highest at 4 kGy. Maximum C₂H₄ production was reached at 1 kGy. The different response of CO₂ and C₂H₄ production to irradiation suggests that the membrane system supporting C₂H₄ production was more sensitive to gamma rays than mitochondrial CO₂ production. Irradiation at 0.3 kGy slightly delayed color development in the fruit. Overall, the results indicated that it may be possible to use irradiation at a low dose to delay ripening while causing only minimal tissue damage.     

REMOVAL OF AFLATOXIN B1 TOXICITY BUT NOT MUTAGENICITY BY 1 MEGARAD GAMMA RADIATION OF PEANUT MEAL

The toxic and mutagenic effects of gamma-irradiated peanut meal contaminated with aflatoxin B₁ were studied in Salmonella typhimu-rium strain TM 677, using forward mutation to 8-azaguanine resistance. After treatment with 5 to 10 M-rad gamma radiation, the contaminated peanut meal lost its toxic and mutagenic properties. Irradiation at 0.1 to 1.0 M-rad removed 75–100% of the toxicity but not mutagenicity.     

VISCOSITY CHARACTERIZATION OF A COMMERCIAL YOGURT AT 5C USING A CUP IN BOB AND A VANE GEOMETRY OVER A WIDE SHEAR RATE RANGE (10−5S−1-103s−1)

Equilibrium viscosity data at 5C, over a wide shear rate range (10^?5 s^?1 -10³ s^?1), are presented for a typical commercially available stirred yogurt. A bob in cup and a vane in cup geometry were used in the work. The vane was manufactured to the same outer dimensions as the bob. A series of constant shear stress creep tests was performed, ranging from 2 Pa to 60 Pa. Equilibrium shear rate values were found for each shear stress. Equilibrium viscosity data obtained with both geometries were of the same order of magnitude. This indicated that slip (wall depletion) effects were not significant with the bob in cup geometry used in the study. Application of existing rheological models showed that the equilibrium viscosity behavior of yogurt may be described using either a power-law of the form or the Cross equation The Cross model better predicted the almost constant viscosities observed at low shear stresses.     

STRUCTURE OF FOODS1,2

A general classification scheme is proposed which recognizes organizational, architectural and relative meanings of food structure and how these relate to textural properties. Within the architectural (or constructive) meaning, one can recognize certain elementary structures which give rise to homogeneous or heterogeneous compounded structures, and permeated or embedded types. Depending on the level of magnification needed, one can also speak of macro-, micro-, and ultrastructures. Specific examples are given and the relatonship between structure and processing is pointed out.     

三元物系液—液萃取过程的计算机辅助计算

本文从液-液两相级式接触萃取出发,在IBM-PC微机上调试出了用于三元物系液-液萃取过程的设计计算和操作计算的程序。该程序收敛速度快,精度高,可替代工业上传统的绘图求解法和繁琐的逐级计算法,而且对工业萃取的优化设计具有现实意义。