Introduction Trends in food spoilage and sa ther than falling, year by year(e.g. Foods deteriorate as a result of phys hanges, the activities of enzymes and of micro- r approximately doubled between 1983 organisms (Table I). In addition, post-harvest losses in the UK, with substantial economic consequences occur due to insect pests. The activities of micro-( Roberts and Sockett, 1994). In developing countries, rganisms are by far the most important quantitatively, food poisoning remains one of the major causes of ading to enormous levels of spoilage(Table II). Losses morbidity and mortality. Control measures are evidently of commodity foods, particularly in the less-well- failing or, at least, not making the progress that we developed countries of the world, are estimated to should expect in the final decade of this millennium exceed 50% for fruits and vegetables and 10% for cereal New approaches to the effective elimination of the most ains and legumes (Anon, 1993). Deterioration in important of the food poisoning micro-organisms from olour, taste and texture of foods is catalyzed by the relatively small number of most frequently contami- endogenous enzymes, and undesirable physiological nated foods are urgently needed. changes, such as ripening and sprouting, degrade food Food preservation technologies The presence of certain micro-organisms in foods The major food preservation technologies, which lead to food poisoning by infection or, if the micro- employed to counteract the deleterious effects of micro multip Food, to intoxication organisms in foods, mostly act by inhibiting or delaying some instances (Table II). Unfortunately heir growth rather than by inactivating them(Table If) developed countries, despite public awareness of food For example, the d, low pH, salts, su poisoning risks, the numbers of food ing cases are preservatives, etc, all act essentially by inhibition. Many Table I Quality loss reactions of foods(adapted from Gould, 1989). Chemical Enzymic Microbiological Mass transfer. movement of low Oxidative rancidity Lipolytic rancidity Multiplication of spoilage MW components micro-organisms Drying, loss of succulence, caking Loss of colour Proteolysis and other Hydration, loss of crisp textures Non-enzymic browning Enzymic browning Multiplication of toxin Loss of nutrients Freeze-induced damagIntroduction Trends in food spoilage and safety Foods deteriorate as a result of physical and chemical changes, the activities of enzymes and of micro￾organisms (Table I). In addition, post-harvest losses occur due to insect pests. The activities of micro￾organisms are by far the most important quantitatively, leading to enormous levels of spoilage (Table 11). Losses of commodity foods, particularly in the less-well￾developed countries of the world, are estimated to exceed 50% for fruits and vegetables and 10% for cereal grains and legumes (Anon, 1993). Deterioration in colour, taste and texture of foods is catalyzed' by endogenous enzymes, and undesirable physiological changes, such as ripening and sprouting, degrade food quality. The presence of certain micro-organisms in foods may lead to food poisoning by infection or, if the micro￾organisms have multiplied in a food, to intoxication, in some instances (Table 11). Unfortunately, in many developed countries, despite public awareness of food poisoning risks, the numbers of food poisoning cases are rising, rather than falling, year by year (e.g. reported cases of disease caused by Salmonella and Campylo￾bader approximately doubled between 1983 and 1993, in the UK, with substantial economic consequences (Roberts and Sockett, 1994)). In developing countries, food poisoning remains one of the major causes of morbidity and mortality. Control measures are evidently failing or, at least, not making the progress that we should expect in the final decade of this millennium. New approaches to the effective elimination of the most important of the food poisoning micro-organisms from the relatively small number of most frequently contami￾nated foods are urgently needed. Food preservation technologies The major food preservation technologies, which are employed to counteract the deleterious effects of micro￾organisms in foods, mostly act by inhibiting or delaying their growth rather than by inactivating them (Table 111). For example, the use of cold, low pH, salts, sugars, preservatives, etc., all act essentially by inhibition. Many Table I Quality loss reactions of foods (adapted from Gould, 1989). Physical Chemical Enzymic Microbiological Mass transfer, movement of low Oxidative rancidity Lipolytic rancidity Multiplication of spoilage MW components micro-organisms Drying, loss of succulence, caking Loss of colour Proteolysis and other enzyme activities organisms Presence of infectious micro￾Hydration, loss of crisp textures Non-enzymic browning Enzymic browning Multiplication of toxinogenic Loss of flavours Freeze-induced damage micro-organisms Loss of nutrients 1