INTRODUCTION Thefactors discussed in this section are intrinsic, extrinsic, and other factorsconsidered in determining whether food, food categories require time /temperature management during storage, distribution, sale and handlingConstitute a comprehensive and non-exclusive list of factors. Retailers andfood services are to ensure consumer protection.
When deciding whether time /temperature control is necessary for safety, many factors must be evaluated foreach particular food item. The need for time / temperature control isdetermined by 1) the possibility of contamination by concerned pathogenicmicroorganisms (including treatment effects), and 2) the possibility ofsubsequent growth and / or toxin production. These can be divided intointrinsic factors and extrinsic factors and other factors.INTRINSIC FACTORMoisture ContentMicroorganismsrequire water in a form that is available for growth in food. Controlling thewater content in foods is one of the oldest utilized storage strategies. Foodmicrobiologists generally describe the water demand of a microorganism withrespect to the water activity (aw) of a food or environment.
Water activity isdefined as the ratio of the vapor pressure of a food substrate to the vaporpressure of pure water at the same temperature 1.PH and AcidityIncreasingthe acidity of foods by fermentation or addition of a weak acid has been usedas a preservation method from long ago. In nature, most foods such as meat,fish and vegetables are slightly acidic, but most fruits are moderately acidic.Some foods such as egg white are alkaline. The pH is a function of the hydrogenion concentration in the food: pH = – log 10 H +. Nutrient ContentMicroorganismsrequire some basic nutrients for the growth and maintenance of metabolicfunction. The amount and type of nutrients required vary greatly with microorganisms.
These nutrients include water, energy source, nitrogen source, vitamins, andminerals 2.Variousamounts of these nutrients are included in the food. Meat has rich protein,lipids, minerals, and vitamins.
Most muscle foods have low levels ofcarbohydrates. Plant foods vary in the variety of carbohydrate, protein,mineral, and vitamin levels. Foods such as milk, dairy products and eggs arerich in nutrition 1..Biological StructureFoodsof plant and animal origin, in particular in the raw state, have a biologicalstructure which hinders invasion and growth of pathogenic microorganisms.Examples of such physical barriers include seeds, fruit and vegetable skin, nutshells, animal skins, egg cuticles, shells and membranes.
During food preparation,slices, chopping, crushing, physical barriers. Thus, the interior of food iscontaminated and growth can occur depending on the essential nature of thefood. For example: Salmonella spp. It is shown that when sufficient time andtemperature are given, it grows inside the part of cut metal, watermelon, honeybee melon 3.Competitive Microbial FloraThepossibility of microbial growth of pathogens in temperature sensitive foodsdepends on the combination of endogenous factors and exogenous factors and thetreatment technique applied.
Within the microflora in food there are manyimportant biological attributes of individual organisms affecting thepredominant species. This includes the individual growth rates of the microbialstrains and interactions or effects between species in the mixed population 4.EXTRINSICFACTORSPackaging / Kind of AtmosphereManyscientific studies have demonstrated the antimicrobial activity of gases atatmospheric pressure and at sub atmospheric pressures against importantmicroorganisms in foods 5.
A variety of common technologies have been used tosuppress the growth of microorganisms, and most of these methods depend ontemperature to increase the inhibitory effect. CAP includes modifiedatmospheric filling (CAP), controlled atmosphere filling (CAS), direct additionof carbon dioxide (DAC), low oxygen storage 6. There are several endogenousand exogenous factors that affect the effectiveness of the antimicrobialenvironment. To determine the extent to which microbial quality and safety areenhanced, it is important to determine the degree to which microbial qualityand safety are enhanced, including product temperature, product to head spacegas volume ratio, initial microbial load and type of flora, package barrierproperties, and food biochemistry Factors interact 7.Influence of TemperatureAllmicroorganisms have minimum, maximum, and optimum, predetermined temperatureranges they will grow. An understanding of the interaction between time,temperature, and other intrinsic and extrinsic factors is important in choosingthe proper storage conditions for the food. Temperature has a dramatic effecton both the occurrence time of the organism and its delay time.
Over thedefined temperature range, the growth rate of an organism is classicallydefined as the Arrhenius relation 1, 8. The relationship between temperatureand growth rate constant greatly varies depending on the microorganism group.Four major groups of microorganisms are described based on the temperaturerange for growth: thermophile, mesophilic, parasitic and parasitic fungus. Theoptimal temperature for thermophilic growth is from 55 to 65 ° C (131 to 149 °F) with a maximum temperature of 90 ° C (194 ° F) and a minimum temperature ofabout 40 ° C (104 ° F).
Mid worms containing virtually all human pathogens havean optimal growth range from 30 ° C. (86 ° F.) to 45 ° C. (113 ° F.
) and aminimum growth temperature in the range of 5 to 10 ° C. (41 to 50 ° F).Vulgaris organisms have an optimal growth range from 12 ° C (54 ° F) to 15 ° C(59 ° F) in the range of 15 ° C (59 ° F) to 20 ° C (68 ° F) 9.Storage and Holding ConditionsThisdiscussion of storage conditions is limited to storage / retention temperature,time / temperature with cooling of cooked goods, and relative humidity to whichfood or packaging material is exposed. The organism has an optimal growth rangeof 43 to 47 ° C. (109 to 116 ° F.
) and a growth range of 12 to 50 ° C. (54 to122 ° F.).
In certain foods, the optimal condition is as short as 8 minutes 10.The FDA’s “Bad Bug Book” states that the presence of numerous B. cereus (over 106 bacteria / g) infood indicates active growth and proliferation of organisms and may be harmfulto health 11.