Relevance Of Sterilisation In Food Processing Industry hp1a

UNIVERSITY OF GHANA, LEGON Department Of Nutrition And Food Science

FDSC 304 – Food Thermal Processing Practicals

Question: Discuss the Relevance of Sterilization in the Food Processing Industry

Kojo Adainoo-Mensah; (ID – 10272528) Lecturer – Prof. E.O. Afoakwa

Introduction The food processing industry is a culmination of a myriad of activities and processes that is essentially aimed at converting raw animal and plant product into safe and shelf-stable food products. Sterilization in the food industry is like the main backbone on which all the other activities depend on to make the industry achieve its purpose in its entirety. It is a very relevant and practically indispensable aspect of the food processing industry because it is the mechanism by which food spoilage and food borne disease causing micro-organisms and bacterial spores likely to contaminate processed foods are destroyed or eliminated. Sterilisation in the food industry encomes bactericidal treatments of the foods and packaging materials as well as sanitization and disinfection of the equipment and environments in which the food is processed. Sterilisation is of key importance due to the ubiquity of microorganisms and their detrimental interactions with food materials (Weisser, 1962). Background and Definition of Food processing This dates back to the prehistoric ages can be referred to as the transformation of raw ingredients into food, or of food into other forms. Food processing typically takes clean, harvested crops or butchered animal products and uses these to produce attractive, marketable and often long shelf-life food products (Liestner, 2000). Similar processes are used to produce animal feed. Food processing techniques like slaughtering, fermenting, baking, salting and smoking were already in use, but modern food processing technology has Nicolas Appert (originator of hermetic bottling technique in 1809) and Louis Pasteur (originator of food sterilization in 1864) are recognised as the ‘fathers’ of the industry. They are recognized as such because they solved the ravaging problem of rapid food spoilage and the acute prevalence

of some food borne disease and laid the foundation for safe food preservation by elucidating the principle of Food Sterilization. Food preservation remains to be the most important of food processing industries. Early approaches to food preservation applied the methods of preservation naturally available, such as sun drying, salting, and fermentation, which were used to provide food in periods when fresh foods were not available. As civilization developed, demand for large quantities of better quality processed food also increased. This led to the development of large food preservation industry aimed at supplying food of high quality in an economical way. And it was Sterilisation that laid at its heart and made this industry an ever increasing success (Fellows, 2000). Sterilisation Sterilisation is basically a process in which all the living microorganisms, including bacterial spores are killed. Sterilization is generally relevant because it minimizes the growth of microorganisms and their contamination of foods to cause diseases. In the environment, the use of disinfection techniques decreases the growth of bacteria on surfaces, which leads to the decrease in transmission of organisms amongst the population. These techniques are commonly used today in medical care and food industry. Sterilisation is one of the most effective means of preserving a large part of our food supply. The objective of sterilization is to extend life of food products and make the food safe for human consumption by destroying harmful microorganism. A sterile product is one in which no viable microorganisms are present. A viable organism is one that is able to reproduce when exposed to conditions that are optimum for its growth. Conditions (temperature, pH, etc) slightly higher than the maximum for microbial growth results in the death of vegetative cells whereas spores can survive at much higher temperatures and thus they are of primary concern in the sterilization process (Larousse and brown, 1997)

As stated above, sterilisation is an important activity in the food processing industry and this process whether physical or chemical, destroys or eliminates all micro-organisms and bacterial spores. Conventional sterilisation techniques rely on irreversible metabolic inactivation or on breakdown of vital structural components of the micro-organisms. Micro-organisms can be destroyed (irreversibly inactivated) by established physical microbicide treatments, such as heating, Ultra Violet (UV) or ionizing radiation, by methods of new non-thermal treatments such as high hydrostatic pressure, pulsed electric fields, oscillating magnetic fields or photodynamic effects; or a combination of physical processes such as heat –high pressure or heat-irradiation. Mechanical removal of micro-organisms from food may be accomplished by membrane filtration of food liquids (Doyle, Beuchat, & Montville, 2001). The objective of sterilization therefore is a practical total deactivation of micro-organisms and biological substances. Sterilisation may be carried out by means of a number of other processes including irradiation, sonication, ultrafiltration, ultra high pressure, heating and chemical methods. Of these processes, heating and chemical methods are the two most important commercially. Chemical methods are most commonly used either to sterilise surfaces for hygiene purposes or to maintain sterility after it has been achieved by other means (that is, as preservatives).

Methods and Uses of Sterilization in the Food Industry Table 2. Different sterilization methods allocated as thermal and non-thermal methods. Method

Industrial relevance

Advantage

Disadvantage

Covers almost all food product groups

„ Direct energy transport to the product (steam)

„ High heat load for the product causing structural and nutritional defects

THERMAL Conventional heat treatment in autoclave/ retort

„ Well established technology „ High food safety

„ Energy consuming

Ohmic heating

Covers almost all food product groups

„ Generates the heat in the food itself, delivering thermal energy where it is needed.

„ Lack of temperature monitoring techniques in continuous systems

„ Particulate temperatures similar or higher than liquid temperatures

„ Differences on electrical conductivity between solids and liquid

„ Faster than conventional heat processing „ Minimal mechanical damage to the product and better nutrients and vitamin retention

„ Lack of data concerning the critical factors affecting heating

„ High energy efficiency because 90 % of the electrical energy is converted into heat „ Ease of process control with instant switch-on shut-down „ Direct energy transfer into the food

High frequency/ Radio frequencyMicrowave

„ No structural damages to food „ Improved food quality: more uniform heating

„ Technology is in a early stage of the development „ High energy consumption „ Not compatible with organic

„ increased throughput „ Shorter processing lines „ Improved energy efficiency „ Maillard reactions may be reduced

NON-THERMAL High pressure

High-acid products like juices, jams, jellies and yoghurts

„ Texture, taste and retention of nutrients are better than for conventional retort. „ Shorter treatment times „ Lower maximum temperature „ Faster heating and cooling

Pasteurization of meats and vegetables

„ Not yet commercial application for shelf-stable low-acid products „ Energy consuming „ Expensive equipment

„ More uniform temperature rise within the product

„ Food should have ca. 40 % of free water for antimicrobial effect

„ In principal independent of the size, shape and composition of the food product

„ Limited packaging options

„ No evidence of toxity

„ Regulatory issues to be resolved

Pulse-electric field

Liquid foods fruits juices, soups liquid egg and milk

„ Kills vegetative cells „ Colours, flavours and nutrients are preserved „ No evidence of toxity „ Relative short treatment time

Accelerated thawing

Ultrasonic waves

Any food that is heated

„ Difficult to use with conductive materials „ Only suitable with liquids or particles in liquids „ Energy efficiency not yet certain „ No effect on enzymes and spores

„ Effective against vegetative cells, spores and enzymes „ Reduction of process times and temperatures

„ Can denaturate proteins and produce free radicals which can affect the flavour (high fat foods)

„ Not accepted in EU at all for food

Microbiocide gas for example ethylene oxide, ethanol, ozone

„ Not compatible with organic foods „ Only for specific foods useful „ Expensive

Irradiation

Ultra-violet

Covers almost all food product groups

„ Pre-packed products can be processed

Dry foods

„ Medium cost

Fresh fruit and vegetables

„ Not accepted in EU at all for food „ Not compatible with organic food

„ Rapid process „ Little or no changes in food

„ Possible adverse chemical effects „ Not proven effective against spores „ Only surface effects (problems with complex surfaces)

Infrared

Low moisture foods

Retrieved from Marjo et al, (2010)

Relevance of Sterilisation in the Food Processing Industry Food sterilisation is necessary for the following reasons: It sanitizes vegetables and fruits, thus killing pests that are usually found on these kinds of food. This kind of sterilization needs lesser doses of electron radiation than that of other kinds of food that have the potential to carry food borne diseases. Dry natural herbs and spices also benefit from the sanitization procedure however, this calls for a greater dosage of electrons. Whatever the food product may be, sterilisation is essential to safeguard the food establishment's track record of safety. Food irradiation and irradiation in general is another procedure that a food sterilization service offers. Food irradiation takes place to help delay or slow down the growth of pathogens on food. This helps your inventory have a longer shelf life, which can help with your finances as well as making sure that the meals in the freezers and on the shelves are still healthy and free of potential unsafe bacteria. Irradiation could also be done on non-food products such as flooring, exposed pipelines, and all other areas of the cooking area. Sterilization in food processing is relevant because it kills micro-organisms that would otherwise lead to food spoilage and food borne diseases (food poisoning, food infection, food intoxication). It ensure products that are shelf stable at ambient conditions. Commercial sterilisation also renders a food product free from all pathogenic or disease causing micro-organism whiles preserving the desirable nutritional and organoleptic qualities of the food. Thermal sterilization (Retorting) additional gets the food product cooked or partially processed. But conversely this can cause over processing, which enhances many negative effects on the food: concentrations of heat-labile vitamins, particularly thiamine, vitamin C and folate are

reduced, organoleptic quality is reduced (Durance, 1997).the texture of the canned vegetables, pasta, fish and meats is often softer than desired; canned milk products may be too brown; the surface of canned meats and other solid-packed products may be darkened by with the inner surface of the hot can, etc. Aseptic processing is the process by which a sterile (aseptic) product (typically food or pharmaceutical) is packaged in a sterile container in a way that maintains sterility. Sterility is achieved with a flash-heating process (temperature between 195° and 295°F (91° to 146°C)),[1] which retains more nutrients and uses less energy than conventional sterilization techniques such as retort or hot-fill canning Aseptic processing is commonly used for the packaging of milks, fruit juices, liquid whole eggs, gravies, and tomatoes. Fresh tomatoes are aseptically processed and packaged for year-round remanufacture into various food products. Sterilisation is of a much keener importance in the production of baby foods due to their high vulnerability to microbial infections since their immune system are nit well developed. Conclusion Sterilisation aims to inactivate bacterial spores and usually uses temperatures above 100° C, since the ideal is to kill or inactivate all viable organisms. However, this is not achievable in practice so the aim is to reduce risk of contamination to an acceptable level. Factors which determine the degree of sterilisation include safety, cost and effect on product From the discussion above, it can be concluded that the relevance of sterilisation in the food processing industry cannot be over emphasized.

REFERENCES Durance, T.D. (1997). Improving canned food quality with variable retort temperature processes. Trends Food Sci.Tecnol. (8), 113-118. Doyle, M.P., Beuchat, L.R. & Montville, T.J. (eds.). (2001). Food microbiology: fundamentals and frontiers. 2nd ed. ASM Press, Washington DC. p. 872 Fellows, P. (2000). Food processing technology –priciples and practise. 2nd

ed. Woodhead

Publishing Ltd., Cambridge. Larousse, J. & Brown, B.E. (1997). Food canning technology. Wiley-VCH, New York. Leistner, L. (2000). Basic aspects of food preservation by hurdle technology. I. J. Food Microb. (55), 181-186. Marjo,S, Vaisanen, H., and Beck, A. (2010) Overview on different sterilisation techniques for baby food. Ruralia Institute, U.H Weiser, H.H. (1962). Practical Food Microbiology and Technology; AVI Publishing: Westport, CT.