Active and intelligent packaging 11 food, respectively. In this case, the material must be in direct contact with the food(Table 2.3) More detailed information about active packaging and its application is available in Chapters 3-5 in Part I and the chapters in Parts II and Ill of this 2.3 Intelligent packaging techniques The definition of intelligent packaging in the Actipak project includes indicators to be used for quality control of packed food (Table 2.4). They can be so-called external indicators, i.e., indicators which are attached outside the package(time temperature indicators), and so-called internal indicators which are placed inside the package, either to the head-space of the pacrackage leak, carbon dioxide (oxygen indicators for indication of oxygen or pa indicators, microbial growth indicators and pathogen indicators) Time-temperature indicators are discussed in detail in Chapter 6, oxygen and carbon dioxide indicators in Chapter 13 and microbial growth indicators, i.e freshness indicators and pathogen indicators in Chapter 7. Furthermore, food ackaging can be intelligent in ways that give information, e.g, about the origin Table 2. 4 Examples of external and internal indicators and their working principle or Adapted from s,2ads to be used in intelligent packaging for quality control of packed food. reacting com Indicator Principle/reagents Gives information Application about Time-temperature Mechanical Foods stored under indicators Chemical Storage conditions chilled and frozen conditions Oxygen Redox dyes Storage conditions Foods stored ackages with reduced (internal Enzymes Package leak gen concentration Carbon diox Storage conditions Modified or controlled indicator Package leak atmosphere food (internal) aging Microbial growth pH dyes Microbial quality of Perishable foods such indicators All dyes reacting food (i.e. spoilage) as meat, fish and (internal/extemal) with certain metabolites(volatiles Various Specific pathogenic Perishable foods suc indicators and immt ical bacteria such as as meat, fish and (internal) methods Escherichia coli with toxins O157food, respectively. In this case, the material must be in direct contact with the food (Table 2.3). More detailed information about active packaging and its application is available in Chapters 3–5 in Part I and the chapters in Parts II and III of this book. 2.3 Intelligent packaging techniques The definition of intelligent packaging in the Actipak project includes indicators to be used for quality control of packed food (Table 2.4). They can be so-called external indicators, i.e., indicators which are attached outside the package (time￾temperature indicators), and so-called internal indicators which are placed inside the package, either to the head-space of the package or attached into the lid (oxygen indicators for indication of oxygen or package leak, carbon dioxide indicators, microbial growth indicators and pathogen indicators). Time-temperature indicators are discussed in detail in Chapter 6, oxygen and carbon dioxide indicators in Chapter 13 and microbial growth indicators, i.e., freshness indicators and pathogen indicators in Chapter 7. Furthermore, food packaging can be intelligent in ways that give information, e.g., about the origin Table 2.4 Examples of external and internal indicators and their working principle or reacting compounds to be used in intelligent packaging for quality control of packed food. Adapted from 5,22 Indicator Principle/reagents Gives information about Application Time-temperature indicators (external) Mechanical Chemical Enzymatic Storage conditions Foods stored under chilled and frozen conditions Oxygen indicators (internal) Redox dyes pH dyes Enzymes Storage conditions Package leak Foods stored in packages with reduced oxygen concentration Carbon dioxide indicator (internal) Chemical Storage conditions Package leak Modified or controlled atmosphere food packaging Microbial growth indicators (internal/external) i.e. freshness indicators pH dyes All dyes reacting with certain metabolites (volatiles or non-volatiles) Microbial quality of food (i.e. spoilage) Perishable foods such as meat, fish and poultry Pathogen indicators (internal) Various chemical and immunochemical methods reacting with toxins Specific pathogenic bacteria such as Escherichia coli O157 Perishable foods such as meat, fish and poultry Active and intelligent packaging 11