Effect of irradiation and chilled storage on the microbiological and sensory quality of a ready meal

The sensory and microbiological quality of both non-irradiated and irradiated cook-chill ready meals consisting of roast beef and gravy, cauliflower and sauce together with roast and mashed potatoes were assessed at intervals during 15 d storage at 2–3°C.
Growth of Pseudomonas spp. caused obvious spoilage of the non-irradiated meals after storage, whereas spoilage was not apparent in the irradiated meals. Irradiation (2 and 3 kGy) reduced the number of microorganisms in the meal to <100 g⁻¹ initially and significant microbial growth did not occur during storage.
Using sensory profiling techniques a trained panel found that the effects of irradiation and chilled storage were most apparent in the cauliflower and potato components and occurred most often in the colour, appearance and textural attributes.
The combination of low dose irradiation and chilled storage effectively controlled microbial growth but changes in the sensory characteristics may limit the potential of irradiation to extend the shelf-life and enhance the safety of this ready meal.     

OPTIMAL CONTROL OF THE PENICILLIN G FED-BATCH FERMENTATION: AN ANALYSIS OF A MODIFIED UNSTRUCTURED MODEL

This paper presents the application of optimal control theory in determining the optimal glucose feed rate profile for the penicillin G fed-batch fermentation, using a modified unstructured mathematical model based on balancing methods. This updated model allows for a smooth transition between maintenance and endogenous metabolism, while all variables take on physically acceptable values under all conditions

It is illustrated that the resulting computational algorithm is independent of the exact nature of the metabolism (maintenance or endogenous). In this scheme, the unusual optimization of some free initial states is included. However, as shown by simulations, the nature of the metabolism might be a key factor in concluding whether or not altering the substrate feeding strategy has an important influence on the final amount of product

Mathematical and microbial insight leads to the construction of an alternative suboptimal heuristic     

Water and Disease After Croydon: A Review of Water-borne and Water-associated Disease in the UK 1937–86

T here W ere 34 outbreaks of water-borne disease recorded in the UK between 1937 and 1986, comprising over 11794 cases and at least six deaths. A total of 21 outbreaks were due to public water supplies, 11 of them contaminated at source; in eight of these 11 the water was unchlorinated or defectively chlorinated. None of the six reported deaths was due to contamination of public supplies at source. About 1000 cases of gastro-intestinal illness were caused by consumption ofafoods, particularly milk and canned nicats, that had been contaminated by polluted water during processing. Shellfish harvested from pollutcd cstuarics gave rise to increasing numbers of outbreaks of viral gastroenteritis and hepatitis A. The recreational use of water was associated with about 400 serious infections and probably many minor illnesses. Sonie hospital infections may have hecn derived from the potable water supply. A total of 14 outbreaks of legionnaires' disease and eight of humidifier fever were associated with water in buildings.
The future control of water-borne and waterassociated disease demands not only continued vigilance in the water industry but closer collaboration between public health doctors and water engineers and scientists.     

Micromechanical properties of tobacco mosaic viruses

A tobacco mosaic virus (TMV) subject to local forces can be viewed as an uniform beam with local loads. We used a custom built Atomic Force Microscope (AFM) to determine the curvature induced in the TMV by concentrated load or by distributed forces. Local forces were created by the AFM tip. Distributed forces were applied to the virus via the surface tension of receding droplets. The experimental results of both methods can be described when we attribute a Young modulus of 6 ± 3 GPa to the virus. Our value is about five times larger than published data. We compare our results to the literature and work out possible error sources in our experiment and in published one.     

SAFETY OF IRISH BEEF – CONCERNS, AWARENESS AND KNOWLEDGE OF IRISH CONSUMERS

A survey of Irish consumers examined their concerns for the safety of food, their level of knowledge of safe food practices and their awareness of institutional structures to ensure the safety of Irish beef. Sixty-four percent of the sample expressed concern for the safety of food. Concerns cited include freshness of food, BSE/CJD, antibiotic residue, hygiene standards and bacteria. They perceive many causes of food poisoning and their level of awareness of pathogens varies, depending on the pathogen. The level of knowledge of safe food practice in cooking was good. However, it was lower for food storage practices. Males and those with lower levels of education were less likely to be aware of adequate food safety procedures and need to be the focus of educational programs on safe food handling. As less than half the sample (49%) was aware of institutional structures and 32% of schemes that ensure the safety of Irish beef, it is concluded that it is imperative to more clearly communicate to the public the assurances of any scheme set up. There is also a need to increase awareness level of the bacteria Campylobacter.     

Quantitative Electron Energy-Loss Measurements on the System ZrO2-CaO

The accuracy of present EELS quantification procedures has been assessed using a directionally solidified eutectic in the system ZrO₂-CaO. In the present study, Ca/O ratios were determined under various operating and analysis conditions and showed good agreement with values calculated from the stoichiometry. Systematic errors in the EELS data were attributed to difficulties in fitting the Ca edge, due to the proximity of other edges in the spectrum, highlighting one of the major problems associated with analysis of multicomponent systems. In addition, sharp discontinuities in the Ca/O ratio were observed when profiling across lamellar interfaces, indicating that EELS shows good sensitivity to abrupt changes in composition and has potential for quantitative light element analysis.