Prediction of pH Change in Processed Acidified Turnips

The acetic acid uptake by turnips was studied during an acidification process in containers. The process was successfully described by a Fickian diffusion, using a correlation for the buffer effect. Diffusion coefficients (0.629 to 3.99 × 10^-9 m²/sec) and partition coefficients (0.8 to 1.1) were obtained by optimization of the fit between experimental and theoretical values, using the simplex method. The partition coefficient did not show an evident dependence on temperature, while diffusivity followed an Arrhenius type behavior. The relationship between acid concentration and pH was described using a cubic model with parameters independent of temperature. Results showed that the combination of these models describing the acid diffusion into the food and the buffering effects of the food allowed accurate prediction of pH evolution in the acidification process.     

Stabilization of linear multivariable constant delay-differential systems

The article presents the iterative method of stabilizing control signal selection in the form of the state-feedback of a multivariable linear time-invariant plant with delays. The proposed method is based on the consecutive assignment of the single system eigenvalues λ_j so that its stabilizability will be preserved for a given iteration step and the assigned eigenvalues will not be changed, even though a dynamical element identified by the matrix K_j(z) (where z is an elementary delay operator) is placed into the state feedback. To illustrate the abovementioned method, a simplified example is given.     

AFLATOXIGENIC ASPERGILLI IN FOODS AND FEEDS IN UGANDA

Studies conducted during the sixties and the seventies on food crops in Uganda showed that the populace was exposed to consumption of aflatoxin-contaminated foods. These studies also linked the highest incidence of liver cancer in the world to the presence of high levels of aflatoxins in the food and beverages. After a lapse of a decade, it was of interest to investigate the occurrence of aflatoxins and aflatoxigenic fungi in staple Ugandan food crops and poultry feeds derived from these foodstuffs. A simple, rapid and reproducible procedure was used. The procedure consisted of growing or culturing feed grains on a selective medium, Aspergillus flavus/parasiticus agar (AFPA) followed by screening for aflatoxin producing fungi on a coconut agar medium (CAM) under UV light with a subsequent confirmatory screening method for aflatoxin production by the fungi in pure culture. Fifty-four samples consisting of corn and peanuts, soybean and poultry feed were analyzed for content of aflatoxigenic. A. flavus/parasiticus and 25 of the samples were also screened for aflatoxins B₁ and G₁, zearalenone, sterigmatocystin, ochratoxin A, citrinin, vomitoxin, and diacetoxyscirpenol (DAS). Aflatoxigenic A. flavus/parasiticus was detected from the majority of corn (77%), peanuts (36% human food and 83.3% animal feed) and poultry feed (66.6%). but not from soybean samples. Two samples out of 25 contained detectable levels of aJatosin B, (20 ppb). For the jirst time other mycotoxins, zearalenone (3 samples) and vomitoxin (2 samples) were detected in corn from Uganda.     

Chemical and Physical Characteristics of Beef Chuck Muscles: Effect of Electrical Stimulation, Hot Boning and High Temperature Conditioning

Chucks from 12 electrically stimulated steer carcasses were randomly assigned to one of 3 treatments: (1) cold boned [CB], (control), (2) hot boned [HB], and (3) hot boned/time conditioned [HB/TC], (5 hr at 18°C). Infraspinatus, Serratus ventralis, Subscapularis, Supraspi-natus, Teres major, and Triceps brachii were excised from each chuck according to treatment conditions. No differences (P > 0.05) were noted among treatments for muscle yields, cooking loss, proximate composition, or collagen content; however, differences (P<0.05) were found among muscles. Differences (P < 0.05) were found among treatments and muscles for ultimate pH, sarcomere length, Warner Bratzler shear values, and Hunter color ‘a’ values. Sarcomere length of muscles assigned to CB treatment were longer (P < 0.05) than HB and HB/ TC treatments.     

IMPROVING FATTY EXTRUDATE STRUCTURE WITH AMYLASE AND PROTEASE

The extrusion of fatty flour at temperatures less than 100C on the one hand favors less leakage of oil from plant and products, but on the other hand reduces the degree of expansion unless suitable technological coadjuvants are used. Enzymes are generally used in the preparation of bread to mellow gluten and to soften texture. At the moment, there is little information about the use of enzymes to improve the texture of extruded products. The effect of two commercially available enzymes (GRINDAMYL Amylase 1000 and GRINDAMYL Protease 41) on the texture of products obtained from wheat and almond flours extruded at low temperature (54C) was studied. GRINDAMYL Protease 41 was found to affect the rheological characteristics of dough by rapid decreasing the consistency during farinographic analyses and by improving the structure of extrudates with a high lipid content (reduced breaking strength, high% porosity and high water solubility index).     

Carotenoid Composition and Vitamin A Value of Fresh and Pasteurized Cashew-Apple (Anacardium occidentale L.) Juice

The carotenoid composition of the red and yellow cashew-apples and two commercial brands of pasteurized juice were determined by column and thin-layer chromatography, visible absorption spectroscopy and specific chemical reactions. Alpha-carotene, β-carotene, ζ-carotene, cis-β-carotene, cryptoxanthin, aurochrome, cryptochrome, and auroxanthin were identified in all samples, with β-carotene as the predominant pigment. Color differences reflected the total amount, not the type of carotenoid present. Geographic effects on the pigment composition did not appear to be appreciable. In the processed juice, the total carotenoid content and vitamin A value were lower but the epoxide level higher. No quantitative differences were noted among lots of the same brand or between brands of pasteurized juice.