Modified Atmosphere Packaging Affects Ascorbic Acid, Enzyme Activity and Market Quality of Broccoli

Reduced ascorbic acid (RAA) content, total chlorophyll and green color retention, enzyme activities and texture changes were followed in broccoli spears packaged in polymeric film and nonpackaged during 96 hr storage (10°C). Concentrations within packages monitored by gas chromatography were (CO₂,) 8% and (0²) 10%. RAA retention, moisture content, total chlorophyll and color retention were greater in packaged broccoli. No differences were found between packaged and nonpackaged broccoli for ascorbate oxidase and peroxidase activities, or texture.     

Nonlinear Variation of Refractive Index of Vitreous Silica with Pressure to 7 Kbars

The variation of refractive index of vitreous silica with purely hydrostatic pressure to 7 kbars was determined from the shift of the localized interference fringes across the specimen kept in an optical pressure bomb. Allowance for the change in the thickness of the specimen was made with the help of Murnaghan's finite-strain theory and the recently determined third-order elastic constants. The refractive index for λ 5893 A increases linearly with pressure with a slope of 9.2 × 10⁻⁴/kbar up to 4 kbars; thereafter it increases nonlinearly. The increase in the refractive index, however, is linear with respect to the Lagrangian strain in the range investigated, except for a slight tendency for departure from linearity at the highest pressures. No hysteresis effects caused by permanent densification were noted. The results are interpreted in the light of Mueller's theory of photoelasticity of amorphous solids.     

Comments on ‘The phenomenon of homeopathic instability in dynamical systems’

Less restrictive sufficiency conditions on system parameters are developed for the existence of homeopathic instability in the class of dynamical systems considered by Johnson. With these conditions, the results are consistent with the earlier work of Youla el at., in particular in terms of the pole-zero interpretation of the sufficiency conditions. A typographical error in the work by Johnson is also noted.     

Effect of Washing Treatment on Quality of Minced Mullet Flesh

Washing treatments were evaluated for quality improvement of minced mullet. Thiobarbituric acid (TBA) number generally decreased with increased washing temperature from 5–35°C and increased at higher temperatures. At 35°C, a wash water pH of 6.0 or above resulted in decreased TBA number. Response surface analysis indicated maximum whiteness index, minimum TBA number, and minimum cooking loss with washing at 29–33°C for up to 10 min with a water to flesh ratio from 23–26. Highest springiness was indicated with washing ratio of 25 to 30 at 28–31°C The simultaneously optimized washing conditions for highest minced mullet quality were 31.4°C for 7.5 min at a ratio of 24.     

ON THE DYNAMICS OF PERIODICALLY FORCED CHEMICAL REACTORS†

A method for studying the dynamics of periodically forced chemical reactors is presented along with the appropriate numerical techniques for its implementation. The method is capable of routinely treating many characteristics of forced oscillatory systems such as subharmonic and related bifurcations, bifurcations to invariant tori and frequency locking. It involves direct solution for the fixed points of the stroboscopic map. This procedure is particularly suitable for detecting certain routes to deterministic chaos such as the Feigenbaum period doubling cascade. Some illustrative examples from a homogeneous catalytic reactor model are included.     

Exopolysaccharide production from whey lactose by fermentation with Lactobacillus delbrueckii ssp. bulgaricus

Ropy Lactobacillus delbrueckii ssp. bulgaricus (strain RR) was used for production of exopolysaccharide in sweet whey and simulated whey permeate (SWP) supplemented with combinations of lactose, KH₂PO₄, NH₄Cl, casamino acids, and mineral salts. Media were incubated at 32, 37, and 44°C for 72h. Periodic adjustment of pH to ～6.2 increased viscosity and lactose utilization, and the free galactose and lactic acid in the media. The effect of pH adjustment was greater than that of supplementation with nutrients or minerals. Fermentation of supplemented SWP generally produced lower viscosities than did fermentation of supplemented sweet whey. After 24h fermentation, viscosity decreased in pH adjusted media. Viscosity of media was highest when incubation was at 32°C and lowest with incubation at 44°C.     

EFFECT OF SODIUM LACTATE, CALCIUM LACTATE AND SODIUM ALGINATE ON BACTERIAL GROWTH AND AMINOPEPTIDASE ACTIVITY

The effects of sodium alginate (0.4 and 0.8%), calcium lactate (0.15 and 0.3%) and sodium lactate (60% solution; 1, 2, 3 and 4%) on growth and aminopeptidase activity of Pseudomonas fragi ATCC 4973 and Salmonella typhimurium in trypticase soy broth or autoclaved ground beef were studied for 5 days at 5°C. Sodium alginate and calcium lactate did not change colony counts of P. fragi or S. typhimurium; and had only slight effects on aminopeptidase activity. Sodium lactate (3 and 4%) showed inhibitory activity on growth and aminopeptidase activity of P. fragi. Sodium lactate also decreased aminopeptidase activity of S. typhimurium but had no major influence on colony counts. In general, aminopeptidase activity was inhibited more than cell multiplication by higher levels of alginate and sodium lactate .     

Scheduling Parallel Computations with Successive CPM Domains

This paper describes a functional procedure for implementation of structural engineering applications in an asynchronously scheduled multi-processor environment. A modification to the classical critical path method is proposed that permits scheduling of networks that contain conditional branching or loops. A general outline is presented, describing the functional requirements of two utility procedures that generate a priority list for scheduling tasks for the particular algorithm of interest. These list-generating utilities, operating with a driver program, work with a modified version of SCHEDULE (a list scheduler) to allocate tasks to processors in an order determined using the weighted-priority heuristic. Programming difficulties inherent in schedule implementation for both shared memory systems and loosely coupled systems (with emphasis on hypercubes) are discussed. The approach is demonstrated on the subspace iteration algorithm.