Az élelmiszer-biztonság és gyártástechnológia

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1 Az élelmiszer-biztonság és gyártástechnológia
Modul 02 - lecke 04, rövidített változat Az élelmiszer-biztonság és gyártástechnológia

2 Az élelmiszertechnológiák célja a kezdeti időkben:
Bevezetés (1) Az élelmiszertechnológiák célja a kezdeti időkben: konzerválás az ételek ízletesebbé és emészthetőbbé tétele Food technologies have existed throughout history. Initially, their objective was to preserve food and/or make it more palatable and digestible, and the search for food preservation methods sometimes led to the development of new foods e.g. wine. While ensuring food safety was not an explicit objective, any technology resulting in an unsafe product was bound to be changed or abandoned. As a science, however, Food Technology is relatively young. Some of the first scientific experiments in this area were done by Nicolas Appert who developed the canning process, to reduce the dependence of the French army on local provisions while on the move.

3 Ma az élelmiszertechnológiának más céljai is vannak:
Bevezetés (2) Ma az élelmiszertechnológiának más céljai is vannak: Új élelmiszerek fejlesztése Az élelmiszerek felruházása kívánatos funkcionális tulajdonságokkal Táplálkozási és organoleptikus minőség fejlesztése A minőség biztosítása With increased understanding of the role of food in the transmission of diseases came the recognition that food technologies have an enormous potential for preventing disease and ensuring food safety. One of the first technologies promoted for public health purposes was milk pasteurization. It was recommended by the Joint FAO/WHO Expert Committee on Milk Hygiene. Today, the objectives of food technology include improving nutritional, organoleptic and functional qualities as well as ensuring food safety.

4 Élelmiszertechnológia és HACCP
Az élelmiszertechnológia alapismeretei segíthetik: a megfelelő ellenőrzési tevékenységek azonosítását (különböző technológiák alkalmazását foglalhatja magában) azon paraméterek kiválasztását, melyek biztosítják a hatékonyságot annak eldöntését, hogyan kell ellenőrizni a paramétereket Food technologies have an important role to play in HACCP, as they often play a role in hazard control. The success of the HACCP system depends in part on the proper selection and application of control measures. Understanding the mechanisms which govern food technologies i.e. parameters which influence the process, and thus the safety of the final product, is necessary for the successful selection of the control measures and monitoring procedures.

5 Cél Megérteni: hogy a különböző élelmiszeripari technológiák hogyan előzhetik meg és /vagy ellenőrizhetik az élelmiszerekben előforduló veszélyeket azokat a faktorokat (paramétereket), melyek hatással vannak a folyamatokra és ezáltal a végtermék biztonságára hogyan ellenőrizhetőek a különböző faktorok (paraméterek) This lecture will explain how different food processing techniques can be used to prevent and/or control hazards in food and describe the factors (parameters) which influence the processes.

6 Az élelmiszeripari technológiák csoportosítása
A technológiák az alábbiak szerint csoportosíthatók: biztonságossá teszi az élelmiszert ellenőrzi a szennyeződést, pl. megakadályozza a mikrobák szaporodását vagy toxintermelését megelőzi a (re)contaminaciót There are different ways to classify food technologies. One is according to the type of treatment that foods receive, e.g. physical or chemical. In the context of HACCP and public health, it is more practical to address food technologies in terms of their role in ensuring food safety, as is shown in this slide. The rest of this lecture will discuss food technologies which render foods safe. The next two modules will discuss technologies to control contaminants and prevent the growth of microorgansims, and those whose purpose is to prevent (re)contamination.

7 Technológiák, melyek bizonyos mikrobákat elpusztíthatnak
Hőkezelés Irradiáció (besugárzás) Fertőtlenítés Fagyasztás (csak paraziták esetén) Túlnyomáson folytatott technológiák By rendering food microbiologically safe, we mean eliminating or reducing a microbiological hazard in the food to a safe level. Examples of such technologies are heat treatment, food irradiation, chemical disinfection, freezing (for parasites), and high pressure.

8 Hőkezelés Módszer Hőközlő közeg főzés sütés / roston sütés forralás
bő olajban sütés grillezés mikrohullámú hőkezelés pasztörizálás sterilezés Hőközlő közeg víz levegő olaj elektromágneses sugárzás hőcserélő / víz nyomás alatti gőz Heat treatment is the most effective and common method for destroying pathogens. Foods can be heat-treated by contact with hot air, steam or hot water, hot oil or a hot surface or by using microwaves. Each of these treatments has a related process: pasteurization, sterilization, microwave treatment, or household or artisan processes such as cooking and boiling. All the processes use similar parameters to ensure the safe application of these technologies. To understand this, we need to examine how organisms behave during a heat treatment process.

9 A hőtűrés a tizedeléis idő (D-érték) határozható meg
No: mikroorganizmusok kezdeti száma N: mikroorganizmusok száma t időben -1 -2 -3 D T (°C) Therefore, the plot of log N/No at a given temperature T against time gives a straight line with a negative slope, k. The number of cells present in the food after different heating periods depends on the initial number of organisms and the death rate k. The reciprocal of the death rate (1/k) is a measure of the organisms’ heat resistance, known as the D value. The D value or decimal reduction time is defined as the time, at a given temperature, for the population to be reduced by 90% or one log 10 value. t

10 Hőtűrés (1) D-érték (min) Vegetatív organizmus Escherichia coli
Salmonella spp. Salmonella typhimurium Salmonella senftenberg Staphylococcus aureus Listeria monocytogenes Campylobacter jejuni 55°C 60°C 65°C 0.1 0.056 4 1.1 The higher the D value, the more heat resistant are the organisms. Vegetative cells are relatively heat sensitive; they will be destroyed by heating food for a few minutes or even seconds. Listeria monocytogenes and Staphylococcus aureus are, among vegetative forms of bacteria of importance in food safety, the most heat resistant. The temperature at which a D value applies is indicated by a subscript e.g. D65. The D value changes with temperature. As temperature increases, a shorter time is required to destroy organisms; therefore the D value decreases.

11 Hőtűrés (2) D-érték (min) Baktériumspóra 100°C 110°C 121°C
C. botulinum A és B C. botulinum E C. perfringens C. sporogenes Bacillus cereus 50 0.3-20 5 < 1 sec Spores of bacteria are usually far more heat resistant than their vegetative forms, and will be destroyed only by temperatures above 100°C. C. botulinum is the most heat resistant spore-forming pathogen, and is of particular concern to the canning industry. To ensure safety, the canning process is designed to achieve a 12-fold reduction of this pathogen. Such a processing or its equivalent is referred to as “botulinum cook”.

12 A hőtűrést (D-értéket) számos tényező befolyásolja:
a mikroorganizmus típusa vagy mikrobatörzs a közeg fiziko-kémiai tulajdonságai, pl. vízaktivitás, pH, összetétel a sejtek kora vagy szaporodási állapota Factors other than temperature influence heat resistance. Bacterial spores are more resistant than vegetative forms, because of their structure and composition and the low water content in their spore core. Yeasts, ascospores and the asexual spores of moulds are slightly more resistant than the vegetative form of bacteria and are normally killed by temperatures between 65 and 100°C. The age and state of growth of microorganisms, and the composition and physicochemical parameters of the medium (such as pH, water activity) also affect heat resistance. For instance, vegetative cells are more heat resistant in their stationary phase than in their log phase. Cells also show greater sensitivity if pH is decreased below 6 or increased above 8. Fat (low aw) enhances heat resistance. Bacterial spores suspended in oil are more heat resistant than in an aqueous system: for example, Salmonella senftenberg is more resistant in milk chocolate than in skim milk. This has implications for pasteurization of high sugar content products such as ice-cream mix. Low water content also increases heat resistance. This means it is more difficult to destroy organisms in a dry medium than in a wet medium.

13 A pasztörizálás típusai
Alacsony hőmérsékletű: 63°C / 30 min Magas hőmérsékletű: 72°C / 15 sec Ultrapasztörizálás: 135°C / 1 sec Pasteurization is a heat treatment of fluid food, intended to kill vegetative forms of pathogens, while causing minimal changes in its composition, flavour, and nutritive values. It can be effective at different time-temperature combinations, for example at 63°C for 30 minutes or at 135°C for 1 second.

14 Hőmérséklet-grágiens a hamburgerben
Heat treatment is not uniform. Depending on the product and the conditions of heat and mass transfer from the heating medium to the product, there will be a temperature gradient in the food. This has important implications for monitoring heat treatment. This figure illustrates the gradient of temperature in a hamburger. Depending on the place the temperature is monitored, these temperatures can vary greatly. To ensure that all parts of the product have received the minimum heat treatment required, it is important to measure the slowest heating point or the coldest point of the product. In this example, as in many other solid foods, the coldest point is the centre.

15 gyors, de nem egyenletes hőkezelés (hideg és meleg pontok)
Mikrohullámú kezelés A hőhatás azáltal keletkezik, hogy az elektromágneses hullámok hatására a vízmolekulák surlódnak (500 MHz - 10 GHz) gyors, de nem egyenletes hőkezelés (hideg és meleg pontok) Products heated by a microwave treatment may show cold and hot spots. In microwave heating, heat is generated due to intermolecular friction between water molecules. Water molecules are dipoles which change orientation under oscillating electromagnetic radiation. A number of factors such as the geometry, physical and dielectric properties of the product influence the heating process and may cause differential heat treatment. Therefore, even if the heat transfer is relatively rapid, caution is necessary: if the structure of a food is heterogenous, not all the parts will be heated at the same rate. This may result in hot and cold spots. The same is true for ohmic heating. In this method, an electric heating current is passed through the material. The heating rate is a function of the electric conductance of the solid and liquid phases.

16 Fagyasztás Paraziták ellen hatásos: kritikus határérték:
- 18°C legalább óráig Nincs vagy csak minimális hatása van: baktériumok, vírusok túlélésére enzimes aktivitásra (polyphenol oxidáz, lipáz) Freezing has two different types of action on microorganisms. In terms of food safety, freezing can be used only to kill parasites and a minimum of 24 to 48 hours at -18°C is needed to kill them. Bacteria and viruses survive freezing. Enzymatic activity such as polyphenol oxidase and lipase may take place. However, since multiplication of microbes is not possible, freezing is an important measure to control microbiological hazards. 46

17 Besugárzás (1) Gamma sugárzás Nagy energiájú elektronsugár
radioaktív anyagok atommagjai bocsátják ki 60Co (felezési ideje 5 év) 137Cs (felezési ideje 30 év) jó behatoló képesség Nagy energiájú elektronsugár gyorsítókkal állítják elő kicsi a behatolási képessége Röntgensugárzás atomi elektronburok belső elektronjai által kibocsátott sugárzás legnagyobb behatolási képesség Food irradiation is another process used to render foods safe. It involves treating food with ionizing radiation of known energy for a specific time to extend shelf-life; destroy or inactivate insects, parasites, pathogenic bacteria, moulds and yeast; prevent decay or ripening of fruits and vegetables; inhibit post-harvest sprouting of tuber and bulb crops. The types of radiation that are used are Gamma rays, electron beams or X-rays. Of these only 60Co (cobalt) and electron beams have achieved major importance. Gy = Gray (az anyag által elnyelt sugárzó energia egysége; 1 gray sugárzást kapott az az anygag, amelynek 1 kg-jában 1 joule energia abszorbeálódott; régebbi mértékegysége a rad; 1Gy = 100 rad = 1 Joule/kg)

18 A mikroorganizmusok érzékenysége
Szükséges dózis paraziták 1.0 kGy baktériumok 1-7 kGy (vírusok > 30 kGy) paraziták G - baktériumok G + baktériumok, penészek spórák, élesztők vírusok The dose needed to ensure safety depends on the type of hazard. The smaller the organisms, the higher is the required dose. The destruction of the organisms is achieved by damage to the genetic material of microorganisms present in the food, either by direct radiation effects on DNA or through the production of radicals and ions that attack DNA. It should be remembered that toxins e.g. mycotoxins or bacterial toxins are radiation-resistant and cannot be inactivated at practical dose levels. Viruses are put between brackets because irradiation is not normally used to kill viruses, since they require a very high dose. +

19 Élelmiszer-besugárzás (2)
Az IAEA, FAO és WHO biztonságosnak ítélte az élelmiszerek besugárzását Az élelmiszerek besugárzása nem érinti a makrotápanyagokat és az esszenciális ásványi anyagokat Bizonyos vitaminok, pl. tiamin és a tokoferolok érzékenyek, de a károsodás mértéke csekély (<10-20%), hasonlóan a hőkezeléshez és a szárításhoz) Consumer organizations have expressed great concern regarding food irradiation. However, it has been assessed as safe at any dose by IAEA, FAO and WHO. In terms of nutritional quality, food irradiation can cause small changes both in macronutrients and micronutrients, comparable to those associated with conventional food processes such as cooking. No significant changes occur to essential aminoacids in beef, fish or other foodstuffs. Minerals and trace elements are also unaffected by irradiation. The effect of irradiation on vitamins varies depending on the food type, the vitamin in question and the process and storage conditions. Some vitamins are easily destroyed (e.g. vitamin B1: thiamine) while others are relatively insensitive. Since irradiated meat, poultry and seafood still have a "fresh" appearance, irradiation could be an important treatment to render raw foods of animal origin microbiologically safe. IAEA = Nemzetközi Atomenergia Ügynökség

20 Kémiai fertőtlenítés Fertőtlenítőszer Alkalmazási terület klór Víz
hypoklorit klór-dioxid jód klóraminok ózon Alkalmazási terület Víz Zöldségek és gyümölcsök Felületek és berendezések Chemical disinfectants can be used to kill different microorganisms. For instance, for water, disinfectants such as chlorine, chlorine dioxide, chloramines and iodine can be used. Chemical disinfection can also be used for fruits and vegetables, surfaces and equipment. In this lecture we will discuss chlorination of water as an example. Disinfection of surfaces and equipment will be discussed in the presentation on cleaning and sanitation.

21 A víz klórozása A klórozás normál körülményei:
szabad maradék klór > = 0.5 mg / l érintkezési idő min. 30 perc pH < 8 a víz turbiditása < 1 NTU NTU = Nephelometric Turbidity Units (a víz fizikai jellemzőiről ad felvilágosítást) Usually, the resistance of different pathogens to different disinfectants is expressed in terms of the C.t value needed to reduce microorganisms by 99%. E. coli is generally the most sensitive. Viruses differ in their sensitivity. Parasites are the most resistant. The efficacy of the disinfection process depends on the purity of the water because the disinfectant may be neutralized by organic matter and readily oxidizable compounds in water. Microorganisms that are aggregated or absorbed by a particular material may also be partly protected from disinfection. It is therefore important to treat the water before disinfection to produce a water with a median turbidity not exceeding 1 nephelometric turbidity unit (NTU) and not exceeding 5 NTU in any single sample.

22 A víz klórozása Ahhoz, hogy a parazitákat elpusztítsák és csökkentsék a víz fizikai szennyeződését, a klórozást kombinálják: koagulálással és flokkulálással filtrációval Both because of inefficacy of a disinfectant on parasites as well as to remove the organic matter, water needs to be treated before chlorination. This treatment includes many steps: coagulation, flocculation, sedimentation and filtration.

23 Zöldségek, gyümölcsök fertőtlenítése
Függ a zöldség és gyümölcs fajtájától Bizonyos mértékű csökkenés elérhető Nem teljesen hatékony Disinfection of fruits and vegetables has also been considered. The disinfection is practised in some developing countries. Although it is not fully effective, it may enhance the safety of some fruits and vegetables. High pressure treatment is a recent technological development. A product in a flexible container is put into a vat filled with a liquid. The vat is pressurized, and the pressure is transmitted through the fluid to all sides of the food simultaneously. The high pressure kills bacteria and spores with different efficiencies depending on some of the parameters mentioned in this overhead.

24 Élelmiszeripari technológiák - a mikrobiológiai veszélyek kialakulásának ellenőrzése

25 Az élelmiszeripari technológiák az alábbiakon alapulnak:
hőmérsékletellenőrzés vízaktivitás ellenőrzése pH-kontroll redoxpotenciál ellenőrzése antimikrobás anyagok To grow, microorganisms have specific requirements in terms of temperature, pH, water activity, redox potential, nutrients. They also need time to grow. Their growth is also influenced by presence of other microorganisms and antimicrobial agents. Nutrients are not a limiting factor in most foods. This module discusses the technologies listed above. The objective of these technologies is to inactivate microorganisms in food, prevent or slow the growth, and/or prevent toxin production.

26 Hogyan befolyásolja a hőmérséklet a baktériumpopuláció szaporodását?
meleg hideg B (Optimum) Szaporodási ráta (K) All organisms have a range of temperatures in which they live and/or grow. Many pathogenic bacteria are mesophilic, which means that they grow best at moderate temperatures of 20-40°C, with a minimum of 5-15°C and a maximum of 40-45°C. As the temperature of food increases above this range, bacterial growth is inhibited and cells eventually die. C (Minimum) A (Maximum)

27 S. typhimurium szaporodása különböző hőmérsékleteken
Idő (nap) 1 2 3 4 5 6 7 8 9 25° 20° 15° 10° Here we can see the effect of temperature on the growth of Salmonella typhimurium. At 25°C, it reaches stationary phase in one day; at 10°C, stationary phase is not reached in five days. At temperatures lower than 10°C, growth is negligible.

28 A patogének szaporodásához szükséges hőmérsékleti tartomány
Hőmérséklet (°C) Min. Opt. Max. Salmonella Campylobacter E. coli S. aureus C. botulinum (proteolytic) C. botulinum (non-proteolytic) B. cereus Here we can see the growth ranges of several foodborne pathogens.

29 A toxintermelő penészek szaporodásához
szükséges hőmérsékleti tartomány Hőmérséklet (°C) Min Opt Max. Penicillium verrucosum Aspergillus ochraceus Aspergillus flavus Fusarium moniliforme Toxigenic moulds are also affected in the same way.

30 Hőmérsékleti zónák BIZTONSÁG VESZÉLY Test- hőmérséklet Hűtés
0° 10° 36.5° 60° 72° 100° BIZTONSÁG VESZÉLY Forrás- pont Pasztörizálás hőmérséklete Fagyasztás Hűtés Test- hőmérséklet Temperature affects microbial growth. Most bacteria found in foods grow best at °C. Some can grow rapidly at °C. Foods should never be kept in warm surroundings for more than one or two hours, although hot storage (> 60°C) is safe for short periods. In the cold, bacteria multiply slowly. Chilling in the refrigerator (optimum 3°C; maximum 10°C) will prevent or slow the growth of microorganisms. A few can multiply under these conditions; in the freezer, most live but do not reproduce. Boiling and pasteurizing kills bacteria in a few minutes but it does not kill heat-resistant spores or destroy heat-resistant toxins. That is why cooked food should be eaten immediately. Here we can see a picture of the critical temperatures, showing that microorganisms grow within a specific temperature range known as danger zone.

31 Psychrotróf patogének
L . monocytogenes Y . enterocolitica C . botulinum (nem proteolitikus) These microorganisms can grow at low temperatures, and chilling alone is not a good technology for prevention of their growth.

32 Vízaktivitás Szükség van a szaporodásához és anyagcseréhez
Az élelmiszerekben lévő víz nem mind hozzáférhető a mikrobák számára A hozzáférhető víz mennyisége a közeg ozmózisnyomásával (Pozm) vagy vízaktivitásával (aw) jellemezhető A kémiai és enzimatikus reakciók szintén befolyásolják a víz hozzáférhetőségét Reduction of water activity is an important technology to control microbiological hazards. The underlying principle is that microorganisms need water to grow. In their natural state, many foodstuffs contain sufficient water to support the growth of microorganisms. By decreasing the amount of water in food or its availability to microorganisms, growth of microorganisms can be prevented. The term “water activity” refers to the availability of water in a food, and should not be confused with water content; a food may have a high water content but if much of this water is bound by food components, it would not be available to microorganisms. It could then be said that the food has a low water activitiy. Water activity affects both the rate of growth of microorganisms and production of toxins, as well as kinetics of chemical and enzymatic reactions. Water activity is the ratio of water vapour pressure of food to that of pure water. It is a value which varies between 0 and 1.

33 Vízaktivitás Aw Reakció- sebesség Szaporodás: Penészek Lipid oxidáció
Élesztők Baktériumok Lipid oxidáció Enzim- aktivitás This curve shows how growth of microorganisms, production of toxins, and physicochemical reactions are affected by water activity. Dried foodstuffs are most stable at a water activity of about 0.2. Nem enzimatikus barnulás Aw 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

34 Az aw minimuma, ahol még szaporodás lehetséges (közel optimális hőmérsékleten)
Penészek Aspergillus chevalieri Aspergillus ochraceus Aspergillus flavus Penicillium verrucosum Fusarium moniliforme 0.87 Élesztők Saccharomyces rouxii Saccharomyces cerevisiae 0.90 Baktériumok Bacillus cereus Clostridium botulinum (proteolytic) Clostridium botulinum (non-proteolytic) Escherichia coli Salmonella Staphylococcus aureus 0.83 Generally, moulds and yeast require lower water activity than most bacteria. Some bacteria, such as S. aureus can grow at quite low aw levels and can cause problems in foods such as salted meats and cheese.

35 Az élelmiszerek vízaktivitása és a lehetséges mikrobák
aw Élelmiszer Mikroba Friss hús Friss hal Friss gyümölcsök Friss zöldségek Sós lében eltett zöldségek Gyümölcsök cukros lében (<3.5 % só, 26% cukor) (C. perfringens, Salmonella) > 0.98 (Pseudomonas) The range of water activity levels in foods is quite large. This table shows that water activity is a selective parameter that determines which microbes will grow. Fermentált húskészítmények Ömlesztett sajtok Kenyér Sűrített tej Sűrített paradicsom (10% só, 50% cukor) (B. cereus, C. botulinum, Salmonella) lactobacillus, bacillus és micrococcus

36 Az élelmiszerek vízaktivitása és a lehetséges mikrobák
aw Élelmiszer Mikroba S. aureus Mycotoxin termelő penészek Romlást okozó élesztők és penészek Fermentált szárazkolbász Nyers sonka (17% só, telített szacharóz) Aszalt gyümölcs Liszt Gabonák Sózott hal Diófélék At water activity <0.6, food starts to become shelf-stable, as no growth occurs but microorganisms may remain viable. This means that as soon as water is added to dehydrated food, precautions required for a fresh food apply because surviving microorganisms can grow again. Xerophil gombák Halofilek Osmophil élesztők < 0.6 Lehet benne túlélő mikroba, de nem szaporodik Édesség Méz Száraztészta Tojáspor, tejpor

37 Vízaktivitás csökkenthető: Vízelvonással (szárítás)
A hozzáférhető víz mennyiségének csökkentése kristályosítással (fagyasztás) A hozzáférhetőség csökkentése a víz megkötésével : pl. só, cukor Various technologies can be applied to control water activity. Old preservation techniques such as salting and jam making etc. are based on lowering the water activity.

38 A patogének szaporodását korlátozó pH-érték
Min. Max. Escherichia coli Salmonella typhi Bacillus cereus Clostridium botulinum Staphylococcus aureus Saccharomyces cerevisiae Aspergillus flavus Fusarium moniliforme Penicillium verrucosum Low and high pH values limit the growth of pathogens. The effect of pH is different for different organisms. These limits can be affected by the nature of the acid.

39 pH és egyéb faktorok A mikroorganizmusok szélesebb pH-tartományban képesek szaporodni laboratóriumi körülmények között, mint ahogy az élelmiszerekben előfordulnak Az élelmiszerekben egyéb faktorok is hatással vannak rájuk, mint pl. : Mikrobák közötti kölcsönhatások Oxigéntenzió Tárolási hőmérséklet Csökkent vízaktivitás A sejtek feldolgozás alatti hőkárosodása It should, however, be remembered that microorganisms can grow at a wider pH range in laboratory media than in foods.

40 pH Savanyítás ecet hozzáadása Fermentáció szerves sav
competitív gátlás antimikrobás szerek These are examples of technologies which are used based on the pH of the food. The effect of some technologies e.g. fermentation is the result of low pH as well as the presence of antimicrobial agents and competitive microorganisms.

41 Különböző élelmiszerek pH-ja
Néhány élelmiszer körülbelüli pH-értéke pH 14 13 12 11 10 9 8 7 6 5 4 3 2 Fermentált cápa Tojásfehérje Here pH values of some foods are listed. We can see that most perishable foods have a pH close to 7. Hal Tej Liszt Zöldségek Hús Sör Üdítőitalok Citrusfélék

42 Redoxpotenciál (Eh) ellenőrzése
Vacuum-csomagolás Módosított atmoszférájú csomagolás: CO2, N2 Microbes are sometimes sensitive to oxygen, but often they need oxygen for multiplication. Controlling the redox potential is therefore a means to control microbiological hazards. The redox potential of a food depends on a number of factors, but availability of oxygen is the most important (ratio of oxidant and reductant, pH, poising capacity, microbial activity). Microorganisms which require a positive Eh need oxygen to grow and are called aerobes. Those which have a negative Eh are obligate anaerobes; this means that they will grow only in absence of oxygen. The redox potential of foods can be controlled either by removal of oxygen by vacuum packaging or modification of the atmosphere by gas flushing.

43 Antimikrobás szerek Sók, pl. nitritek Bacteriocinek, pl. nisin
Gáz: pl. CO2 Szerves savak / sók, pl. benzoesav, szorbinsav és propionsav In addition to controlling physical parameters, it is also possible to use antimicrobial agents to control the growth of microorganisms. Depending on the food product and microorganisms, different antimicrobial agents can be used. For instance, sodium nitrite is used in the production of ham to control the growth of C. botulinum. It also gives the meat the desired pink-reddish colour. Bacterocins, e.g. nisin are active against pathogens such as Listeria monocytogenes, C. botulinum, and Staphylococcus. The effects of antimicrobial agents on microorganisms are often selective and they are generally used to control specific organisms. Their effectiveness also depends on environmental factors, such as temperature, pH, concentration and contact time. Some technologies are based on a combination of several factors or processes. Smoking makes use of both heat treatment, drying and sometimes also antimicrobial agents present in the smoke. These techniques are sometimes referred to as "hurdle technologies.„ To achieve safety, a combination of several technologies is applied, e.g. milk is pasteurized or sterilized and aseptically packed to prevent re-contamination. In this situation, different technologies are applied with different objectives, i.e. decontamination and protecting from re-contamination. However, different technologies are sometimes combined to reach a single objective. This type of application of food technologies is referred to as “hurdle technology” i.e. a technology which is based on several factors affecting growth and survival of microorganisms. Fermentation and curing (low pH, microbial inhibitors, competitive microflora) are examples. Refrigerated processed foods of extended durability include foods where a combination of various technologies are applied with a specific objective, but with minimal changes in the nature of the product. These foods are cooked at lower temperatures than canned foods, to produce the desired organoleptic changes. After heating, products are rapidly cooled and stored under refrigeration. Very often these products are vacuum packed, either before or after the heat treatment. The safety as well as the suitability (prevention of spoilage) of the product is ensured by a combination of heat treatment, refrigeration and vacuum packaging.

44 További műveletek és jelentőségük
Csomagolás Az üzem, gyártóvonalak és berendezések higiéniai tervezése Tisztítás, fertőtlenítés Even if the food is rendered safe and microbial growth is controlled, it is important to protect the food from recontamination. This module will discuss packaging technology and its role in ensuring food safety. Hygienic design of factories, and cleaning and disinfection, are also important for preventing recontamination. They will be discussed in separate modules.

45 Csomagolás Megelőzi a rekontaminációt
A szilárd élelmiszereket védi a nedvességfelvételtől Alacsony oxigénkoncentrációt tart fenn Védi az élelmiszert a fénytől Packaging, whether in metal, glass, paper or plastic fulfils many objectives. In terms of food safety, it is important in preventing contamination, protecting food against moisture which may have adverse effect on microbial as well as chemical and enzymatic reactions. Many pathogens and spoilage microorganisms need oxygen to multiply; thus many packaging materials are impermeable and hermetically sealed. It also protects the food against light, thereby preserving the quality of the food. There are two ways of packaging liquids (not including water). The usual way is to put hot or warm food into the container, and sterilize package and food together after sealing, if necessary (low acid foods). In the aseptic way the food and the package are prepasteurized/presterilized separately and the food is filled in an aseptic atmosphere where no recontamination can occur. Compared to conventional packaging, the time of filling and heating in aseptic processing is relatively short (up to 60 s). The cleaning process depends on the product to be packaged and on the type of packaging material. Heating with saturated or superheated steam is the oldest technique and is applied to cans. A mixture of hot air and steam is also used for surfaces made of polypropylene, which has thermal stability up to 160°C. Temperatures up to °C are used for about 3 minutes in the blow moulding process of plastics. As temperature distribution may not be uniform, chemical re-sterilization may be needed. Chemical sterilization is usually carried out with hydrogen peroxide (H2O2). The material is dipped, rinsed or sprayed with H2O2. The process is followed by heating to remove the residues of H2O2 and to increase the effectiveness of the process. Infrared light (IR) is used as a dry heat irradiation and can be applied only to heat resistant surfaces. Ultra-violet (UV) irradiation is a kind of surface sterilization often used in combination with H2O2. Ionizing radiation is also used for plastic bags. The most critical part of the process is the aseptic filling of the pre-sterilized food which should be carried out under the most hygienic conditions. There are various types of packaging for liquid foods. The choice of the packaging material, be it for solid or liquid food, requires good knowledge of the preservation process and characteristics of the food. Glass bottles are used mainly for alcoholic beverages, as well as juices and soft drinks. Cans made of aluminium or tin-coated steel are used for packaging carbonated soft drinks and beer. Laminated cardboard is used for dairy products. The packages are made of paperboard coated with polyethylene on both sides. For longer shelf-life a high-barrier layer, made of thin aluminium foil or plastic material can be included. Plastic bottles are usually made of high-density polyethylene. Carbonated beverages are often packed in polyethylene terephthalate (PET) bottles.

46 Csomagolás - Összefoglalás
A csomagolás célja, hogy megóvja az élelmiszereket a minőségét érintő változásoktól, beleértve a mikrobiológiai és fiziko-kémiai változásokat A változások fő okai a vízgőz vagy nedvesség , az oxigén, fény és a kémiai anyagok A lehetséges veszélyek a csomagolóanyagokkal és magával a csomagolási folyamattal hozhatók összefüggésbe A csomagolóanyagok kiválasztásának szempontjai: stabilitás, a konzerválási folyamat funkciója, az élelmiszer jellemzői Unless a high-barrier polymer is included, PET bottles are slightly permeable to carbon dioxide, and the shelf-life of the product may be shorter than when packed in glass bottles. Several hazards are associated with packaging material or processes. Glass bottles are sometimes difficult to clean and may contain glass splinters. It is also necessary to assure effective sealing. Metal containers may corrode. This can be avoided by strict specification for metal quality, use of lacquer coating, and good container manufacturing practice. Although no specific hazards have been associated with PE and PET bottles, they may release remnants of heat-formed acetaldehydes. These can alter the taste of the beverage, residual acetaldehyde may need to be tested in these packages but this should not be seen as monitoring of a CCP. Again, the choice of the packaging material requires good knowledge of the preservation process, stability and characteristics of the food e.g. water activity, lipid content and structure. Water activity is an important parameter in this context as it regulates both microbial and physico-chemical reactions. Therefore solid foods may be divided into those with high and low water activity i.e. above and below This differentiation is also related to the rheological properties of the food; i.e. foods with low water activity are generally rigid and non-deformable (except for powders), and those with high water activity are less rigid and deformable. Depending on the objectives (level and type of protection, shelf-life and type of product), the following criteria need to be considered when choosing the packaging material: acceptance by the legislation, thickness, the type of packaging material, the structure i.e. mono- or multilayer, coated or metalized. Most foods are sensitive to water vapour. Therefore, most packaging material provides some protection against water vapour. Foods containing fat e.g. snacks and crisps, need high protection against light. Packaging material must comply with the regulations of the countries where the foods will be used. Successful packaging also depends on the equipment. Depending on the objectives (level and type of protection, shelf-life and type of product), the following criteria need to be considered when choosing the packaging material: acceptance by the legislation, thickness, the type of packaging material, the structure i.e. mono- or multilayer, coated or metalized. Most foods are sensitive to water vapour. Therefore, most packaging material provides some protection against water vapour. Foods containing fat e.g. snacks and crisps, need high protection against light. Packaging material must comply with the regulations of the countries where the foods will be used. Successful packaging also depends on the equipment.