The Significance of Theoretical Results in the Dyeing of Acrilan 16 with Basic Dyes from an Anhydrous Perchloroethylene Dyebath

Theoretical principles used in an investigation of the mechanism of carrier dyeing and the plasticization of acrylic fibres have been applied successfully to the dyeing of Acrilan 16 with basic dyes from an anhydrous solvent dyebath. Part I deals with the selection of plasticizing agents and Part II describes the dyeing procedure and properties of the resulting basic dyeings.     

Flavonol composition of Australian red and white wines determined by high‐performance liquid chromatography

Background and Aims: Flavonols are present in Vitis vinifera L. wine grapes as glycosides and are found in wines in both their glycosidic and aglycone forms. Flavonols and their glycosides are important components in wine because of their impact on colour, taste and health properties. An assessment of the flavonols and flavonol glycosides present in a wide selection of Australian red and white wines (n = 121 and 44, respectively) was undertaken. Methods and Results: Analyses were performed using HPLC, with compound identification being aided by HPLC‐MS. In the red wines, quercetin and myricetin dominated the flavonol profile, and quercetin‐3‐glucuronide was by far the most abundant glycoside present. White wines had considerably lower levels of flavonols and their glycosides, in most cases, being below the detection limit of the HPLC method. Conclusions: There appeared to be no correlation between the flavonol profile and wine variety or region in either white or red wines. Contrary to literature reports of rutin in wine, rutin was not found in any of the wines we analysed, and spiking experiments showed rutin rapidly degraded to the aglycone quercetin. Furthermore, changes in elution order for some quercetin glycoside standards were observed depending upon the acid used in the mobile phase. Significance of the Study: This is the first time the flavonol contents of an extensive cross section of Australian wines have been reported. The concentrations are consistent with those reported in wines from other countries. In light of the instability of rutin in wine, critical review should be given to reports discussing its presence.     

Assembly line system dynamic behaviour for high priority job order processing

Very often in a manufacturing plant, an important job order must be processed with higher priority than other regular jobs. It is vital for management to understand the impact on production performance of these high priority job orders. In this paper, this dynamic behaviour of assembly line systems is studied using computer simulation and derived metamodels in the form of mathematical expressions. An extensive computer simulation study is first conducted off-line. Next, analytical representations of the system lmetamodels) are fitted to the dynamic behaviour as simulated. These relatively simple equations can then be used on-line to estimate the impact of high priority job order processing when it occurs. The results indicate that the system response to this dynamic event can be described by first-order exponential delay functions captured in metamodels from simulation results. Using only the metamodels, the finish time of high priority jobs can be predicted and the number of delayed regular assembly products can be estimated in real time in the shop floor. This information is very valuable and useful for production scheduling.     

MATHEMATICAL MODELING OF MICROBIAL GROWTH: A REVIEW

The use of mathematical modeling of microbiological behavior to predict and evaluate food safety or shelf life is receiving considerable interest. Researchers are attempting to use mathematical equations that incorporate such critical growth factors as pH, a_w, and NaCl content to predict microbial growth and/or toxin production in order to replace traditional time-intensive challenge studies. Predictive equations can be divided into probabilistic, regression, Arrhenius, and square root models. Models vary greatly in theory and complexity. Predictive models are used to monitor processes ranging from temperature during distribution to inventory control. They have been shown to be useful in product development and shelf-life estimation when safety is not an issue. Most models are generated by regression analysis of data obtained from laboratory experiments. Statistically based models, even when conservatively derived, are not appropriate as the only criterion for evaluating food safety.     

COOKING EFFECTS ON TITIN IN FRESH AND PROCESSED BEEF PRODUCTS

Fresh bovine longissimus thoracis muscle samples, heated at 73C for 0, 5, 15, 30, 45, 60, 90 and 120 min, were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis and western blot analysis. Titin was both aggregated into large protein masses and degraded into smaller fragments (two apparently independent processes) in fresh muscle samples heated 15 min or more at 73C. Samples removed at various points during the manufacture of a tumbled cured beef product were also subjected to electrophoresis and western blot analysis. Titin was primarily degraded into smaller polypeptide fragments during the manufacture of this product with no large titin aggregates observed. Commercially manufactured meat products, when examined by these techniques, contained both titin aggregates and degradation products. These results suggest that titin can be aggregated into large protein masses and degraded into smaller polypeptide fragments during the heating of fresh or processed meat products.     

Control of Enzymatic Browning in Processed Mushrooms (Agaricus bisporus)

Control of polyphenol oxidase (E.C. 1.14.18) activity by the use of citric acid was investigated. The enzyme was inactivated at pH 4.0 and was stable to 10 min exposures at 25°C in the pH range 4.0–8.0. At pH 6.5 the enzyme was active at 45°C but not at 70°C and thermal inactivation followed pseudo first-order kientics. At pH 6.5 the activation energy (E_a) for enzyme inactivation was 41.1 Kcal/mole while at pH 3.5 two rate constants and hence two values for E_a were observed. Between 0–5 min E_a for inactivation of polyphenol oxidase was 8.7 Kcal/mole and >5 min Ea was 21.8 Kcal/mole.