Paper No.: 03 Paper Title: FOOD MICROBIOLOGY Module – 35: Application of hurdle technology in food industry (e-Text and Learn More) Component-I (A) - Personal Details: Role Name Affiliation National Coordinator Professor R.C. Kuhad University of Delhi South Campus New Delhi Subject Coordinator Professor Vijayakhader Former Dean, Acharya N.G. Ranga Agricultural University, Hyderabad Paper Coordinator Professor A. K. Puniya National Dairy Research Institute (NDRI), Karnal Content Writer/Author Dr. Pradip Behare Content Reviewer Language Editor (LE) Technical Conversion FOOD APPLICATION OF HURDLE TECHNOLOGY IN FOOD INDUSTRY MICROBIOLOGY Component-I (A) - Module Structure: Structure of Module/Syllabus of a module (Define Topic of module and its subtopic) Introduction, Principle of hurdle technology, Hurdle, Basic Aspects of Application of Hurdle Hurdle Technology, Homeostasis, Metabolic exhaustion, Stress Technology in Food Industry reactions, Multitarget preservation, Individual Hurdles, Microbiocidla Hurdles Reduces Microbial Load, Microbiostatic Hurdles (Chemical Hurdles), Microbiostatic Hurdles (physical Hurdles), Hrudles that prevent contamination, Application of hurdle technology in foods. Component-II - Description of Module Description of Module Subject Name Food Technology Paper Name Food Microbiology Module Name Application of Hurdle Technology in Food Industry Module Id FT/FM/35 Pre-requisites Hurdles, Concept, Hurlde technology in dairy and food products Objectives To study about types of hurdles and their application in food industry Keywords Hurdles, dairy foods, salt, sugar, high-pressure, hurdle concept FOOD APPLICATION OF HURDLE TECHNOLOGY IN FOOD INDUSTRY MICROBIOLOGY TABLE OF CONTENTS Table No. Description Table 2.1 Examples of hurdles used to preserve foods Table 3.1 Role of Microbiocidla Hurdles Table 3.2 Role of Microbiostatic hurdles Table 3.3 Role of Microbiostatic Hurdles Table 3.4 Role of Hurdels in Preventing Contamination Table 4.1 Application of Hurdle Technology in Dairy and Food Products FIGURES OF CONTENTS Table No. Description Figure 2.1 Basic concept of bacterial inhibition by hurdles Figure 4.1 Preservation of food by individual and combined hurdles FOOD APPLICATION OF HURDLE TECHNOLOGY IN FOOD INDUSTRY MICROBIOLOGY 1. Introduction 2. Principle of hurdle technology 2.1 Hurdle 2.2 Basic Aspects of Hurdle Technology 2.2.1. Homeostasis 2.2.2. Metabolic exhaustion 2.2.3 Stress reactions 2.3 Multitarget preservation 3. Individual Hurdles 3.1 Microbiocidla Hurdles Reduces Microbial Load 3.2. Microbiostatic Hurdles (Chemical Hurdles) 3.3. Microbiostatic Hurdles (physical Hurdles) 3.4. Hrudles that prevent contamination 4. Application of hurdle technology in foods 5. Summary FOOD APPLICATION OF HURDLE TECHNOLOGY IN FOOD INDUSTRY MICROBIOLOGY 1. INTRODUCTION The primary objective of traditional and newly developed food preservation processes is the inhibition or inactivation of microorganisms that ultimately helps to improve shelf stability of food. Every food has certain inherent preservation factors such as extent of heat treatment received (F), water activity (aw), low temperature storage (t), redox potential (Eh), pH, etc. which may be termed as hurdles, because microorganisms will have to 'jump' these hurdles in order to grow and spoil the product. The stability of the product depends upon the intensity of hurdles present in it. More the intensity or height of these hurdle, or more the number of these hurdles, more difficult it will be for microorganisms to overcome these hurdles. In conventional preservation method the intensity of one or two of these hurdle is exceptionally increased making it extremely difficult for microorganisms to overcome that hurdle. For example, in sterilization process F-value (i.e. the amount of heat treatment given) is increased to 3 to 15. Or in dehydration the water activity (aw) is decreased to a very low value i.e. 0.85. Such increase or decrease in the intensities of these parameters adversely affects the quality of certain products. Microbial stability and safety, as well as the sensory and nutritional quality of most preserved foods, are based on a combination of several empirically applied preservative factors (hurdles), and more recently on knowingly employed hurdle technology. Deliberate and intelligent application of hurdle technology allows a gentle, efficient preservation of foods, which is advancing worldwide. Many foods can not be preserved by a single hurdle alone without affecting their sensory and nutritional properties. Therefore, hurdle Technology is the combination of selected hurdles, which can keep microbiological hazards and other microorganisms under control, with or without combinations with microbial steps, so as to obtain and retain end product safety or suitability. 2. PRINCIPLE OF HURDLE TECHNOLOGY The most important hurdles commonly used in food preservation are temperature (high or low), water activity (aw), acidity (pH), redox potential (Eh), preservatives (nitrite, sorbate, sulfite, etc.), and competitive micro-organisms (e.g., lactic acid bacteria). More than 60 potential hurdles for foods of animal or plant origin, which improve the microbial stability and/or the sensory quality of these products, have been already studied, and the list of possible hurdles for food preservation is by no means complete. At present, physical, non-thermal processes (high hydrostatic pressure, oscillating magnetic fields, pulsed electric fields, light pulses, etc.) receive considerable attention (Non-thermal Processing), since in combination with other conventional hurdles they are of potential use for the microbial stabilization of fresh-like food products, with little degeneration of nutritional and sensory properties. Another group of hurdles, of special interest in industrialized and developing countries at present, would be „natural preservatives‟ (spices and their extracts, lysozyme, chitosan, pectin hydrolysate, etc.). In most countries, these „green preservatives‟ are preferred because they are not synthetic chemicals, but in some developing countries, they are given preference, since FOOD APPLICATION OF HURDLE TECHNOLOGY IN FOOD INDUSTRY MICROBIOLOGY spices are readily available and cheaper than imported chemicals. The critical values of many preservative factors for the death, survival, or growth of micro-organisms in foods have been determined in recent decades and are now the basis of food preservation. However, the critical value of a particular parameter changes if additional preservative factors are present in the food. For instance, it is well known that the heat resistance of bacteria increases at low aw and decreases at low pH or in the presence of preservatives, whereas low Eh increases the inhibition of micro-organisms due to reduced aw. The simultaneous effect of different preservative factors (hurdles) could be additive or even synergistic. In food preservation, the combined effect of preservative factors must be taken into account, which is illustrated by the hurdle effect. 2.1 Hurdles Microbial growth is dependent upon many conditions in the organism‟s environment such as ingredients; nutrients, water activity, pH, presence of preservatives, competitive microorganisms, gas atmosphere, redox- potential, storage temperature and time (Table 2.1). Control of these conditions can therefore be used to limit, retard or prevent microbial growth. One major use of hurdles is to prevent or restrict the growth and/or to reduce the concentration of microorganisms, including target pathogens in milk, intermediate and final milk products. Most milk products need the use of hurdles to become safe and suitable and/or to retain such quality. Table 2.1. Examples of hurdles used to preserve foods Type of hurdle Examples Physical hurdles Aseptic packaging, electromagnetic energy (microwave, radio frequency, pulsed magnetic fields, high electric fields), high temperatures (blanching, pasteurization, sterilization, evaporation, extrusion, baking, frying), ionic radiation, low temperature (chilling freezing), modified atmospheres, packaging films (including active packaging, edible coatings), photodynamic inactivation, ultra-high pressures, ultrasonication, ultraviolet radiation Chemical hurdles Carbon dioxide, ethanol, lactic acid, lactoperoxidase, low pH, low redox potential, low water activity, Maillard reaction products, organic acids, oxygen, ozone, phenols, phosphates, salt, smoking, sodium nitrite/nitrate, sodium or potassium sulphite, spices and herbs, surface treatment agents Microbial derived Antibiotics, bacteriocins, competitive flora, protective cultures FOOD APPLICATION OF HURDLE TECHNOLOGY IN FOOD INDUSTRY MICROBIOLOGY hurdles 2.2 Basic aspects of hurdle technology The strength or intensity of a hurdle will normally not be sufficient to render the food as safe, but in combination with other hurdles the desired effect can be achieved. Therefore, to ensure the safety and suitability and or to extend the shelf life of milk products, generally more than one hurdle is needed to control microbial content and or growth, to inhibit spoilage and to help prevent food borne diseases. Suitable combinations of hurdles can be devised so that the organisms of concern can be reduced in number and or no longer grow/survive in the product. Such suitable combinations are called “Hurdle Technology”. Many hurdles act by interfering with the homeostasis mechanisms that microorganisms have evolved in order to survive environmental stresses. Maintaining a