Sterilisation of food

Following the favourable response of this committee, steps were taken to amend the existing UK legislation which permitted only the radiation sterilisation of foods for people whose immune response was compromised. New regulations came into force in early 1991 which permitted the irradiation of seven groups of foods under strictly controlled conditions (Anon., 1990a) (Table 1). 

Chemistry (Theoretical and Applied).—Air. Water. Chemical theory. Acids, alkalies and salts. Carbon and its oxides fuels. Soaps. Textile fabrics. Water softeners. Sugars, starch, alcohol, acetic acid. Proteins. Fats. Yitamines. Yeasts, moulds and bacteria. Study of certain foods. Preservation and sterilisation of food stuffs. The practical work will be partly illustrative of the lectures, and partly experimental craft work, i.e. —... 

Wilson DR, Dabrowski L, Stringer L, Moezelaar R, Brocklehurst TF. 2008. High pressure in combination with elevated temperature as a method for the sterilisation of food. Trends Food Sci Tech 19 289-299. 

Garrison, W.M. (1981). The radiation chemistry of amino acids, peptides and proteins in relation to the radiation sterilisation of high-protein foods. Radiat. Effects 54, 29-40. 

M. Lewis and N. Heppell, Continuous Thermal Processing of Foods — Pasteurisation and UHT Sterilisation, Aspen Publishers, New York, 2000. 

The direct sterilisation of particulafe solid foods in a gas-solid fluidized bed was proposed as long ago as 1968 by Lawrence et al. (1968) who sterilised wheat flour in steam-air mixtures at the pilot scale. However, Jowitt (1977) described an atmospheric pressure process for fhe sferilisation of canned foods in which the cans are immersed in a fluidized bed of inert particles. This has a number of advantages compared to the conventional retorting process using pressurised steam or hot water ... 

Aseptic processing is used to achieve commercial sterility in a continuous flow of liquid or semi-liquid food by heating the food to a suitable temperature before placing it in previously sterilised packaging. The sterilisation of liquids containing particulates presents a number of... 

Sterilisation of blood products and other organ transplant tissues opens another area for photodynamic effect applications. Photodynamic activity of some inorganic sensitizers together with their photocatalytic activity can be very useful in water, air, and surface detoxification (see Chapter 21). APDT can be a new approach for safe food. The reduction of several Gram-positive bacteria and yeasts has been observed in tests with visible light and haematoporphyrin or chlorophylls (natural constituents of food) as photosensitizers [54],... 

Polyethylene naphthalate (PEN) polyesters are made from 2,6-naphthalene dicarboxylic acid or 2,6-naphthalene dicarboxylic acid, dimethyl ester. They have higher temperature resistance than amorphous PET and are increasingly used in applications requiring heat sterilisation of the food/drink, although PEN at the moment is significantly more expensive. Table 10.5 lists commonly used substances in polyesters. 

One result of this development work is an instrument for accurately measuring a key property of can coatings, the sterilisation resistance. First, however, a brief description of can coatings and some of their properties is in order. The discussion will be limited to coatings to be applied to the interior of food-or beverage-containing cans since this application requires the highest chemical resistance. Most of the work described has been carried out with can lacquers of the solid epoxy resin/phenolic-formaldehyde (E/PF) type as these are the predominant type used in Western Europe. 

Jayaram, S.H. 2000. Sterilisation of liquid foods by pulsed electric fields. IEEE Electrical Insulation Magazine 16 17-25. 

Where steam is used for cleaning, to sterilise either plant or product by direct injection, then it can become an integral part of the food. The composition of steam must therefore be controlled with respect to the additives employed for treatment. Since it is possible for chemicals added to boiler feed water to be carried with the steam to the point of use. No boiler feed water treatment chemical should be employed till it has been shown to be safe in respect of food product quality. In the UK permitted chemicals include [HMSO 1983] ... 

In industrial and also in culinary practice, methods based on physical principles are widely used in addition to these chemical methods of food preservation. Of these, it is primarily food preservation by heat treatment (pasteurisation and sterilisation), cold (chilling and freezing), drying (dehydration), irradiation, and more recently by high pressure, which attract the most attention. 

Effective substances against all microorganisms (vegetative forms and spores) and also with insecticidal properties are ethylene oxide (oxirane) and propylene oxide (methyloxirane). In some countries, these compounds are approved for fumigation of foods with low water contents, where other methods of preservation are not applicable (such as sterilisation of spices, nuts, starch and flour). The modern alternative is irradiation. 

Hozova, B. and Takacsova, M., The influence of combined storage procedures of foods on B vitamins content demonstrated at the example of heat sterilisation and irradiation. Die Nahrung, 38(4), 345-351, 1993. 

Interest in the use of ionising radiation in the food industry was aroused in the mid-fifties with the availability of large isotope sources and the development of suitable electrical machines such as the linear accelerator. In particular, attention focused on the radioisotope cobalt 60 as a source of gamma rays. During the past 25 years it would be a reasonable estimate that some 50 million curies have been installed in plants situated in various parts of the world. However, the majority of these are employed for the sterilisation of disposable medical products, pharmaceuticals, cosmetic preparations, and laboratory animal diets. Only a few commercial fecilities have been constructed for the processing of human foods. 

To prevent contamination of contents of prepacked products, pharmaceutical or food by packaging material itself Sterilisation of packaging material before use 1 0-2 5... 

It is worthwhile drawing attention to health hazards associated with film infected water systems which also cause corrosion. Two of the most common are Legionnaires disease and so called humidifier fever . Because of strong adhesion of biofilms and diffusion rates through the film treatment based on cleaners and chemical sterilisers such as chlorine often fail similar considerations apply to other systems in industry, e.g. food, paint, oil and gas are examples where biofilm activities have given massive problems. 

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