The control of micro-organisms in the foodstuff

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The control of micro-organisms in the foodstuff in principle aimed at making the foodstuff become durable, or in other words had a purpose for conservation of the foodstuff. The control of significant micro-organisms prevented the growth of micro-organisms that could mean to kill or hinder the growth personally. Usually this action is carried out with the physical treatment or the treatment of chemistry. The physical treatment could be carried out by means of the thermal treatment, the treatment of drainage and the treatment of the illumination (irradiation). The thermal treatment consisted of the low temperature, that is the refrigeration and the freezing, and the high temperature/the heating that could take the form of pasteurisation or the sterilisation. The treatment of drainage could be carried out by means of drainage or the frozen drainage method. The treatment of the illumination could be carried out with ultraviolet rays and ionisation (the rays röntgen, the gamma ray, the electron rays). The treatment of chemistry could be carried out by means of penggaraman, curing, pengasaman, fumigation and giving of preservatives.

The thermal treatment

The temperature was the important extrinsic factor that influenced the growth of micro-organisms. Compared with the high-level creature, micro-organisms had very wide growth extension (approximately – 15 s/d 90 °C). In the low temperature, his growth will stop, whereas in the high temperature of this organism will die. In the two situations above, related the process of the occurrence of metabolism that caused the occurrence of foodstuff damage. Because of the process enzimatik also depended on the temperature, then the treatment will with the temperature of the extreme cause conservation almost all the foodstuff. The temperature rendah The low temperature did not kill micro-organisms but hindered his proliferation. Therefore the growth of micro-organisms increasingly decreased together with increasingly the low level of the temperature, and finally below “suhu the growth minimum” his proliferation will stop. The temperature of the minimal growth that was sealed in the Table 1 only the estimate figure and experimentally only was current for several strain from the certain species and could not be current the public. In the storage of the foodstuff in the frozen temperature, the process of the disintegration by micro-organisms still could be happening although really was slowed down. The process of damage just could be stopped in the temperature below -18°C.
The minimal temperature only was valid when in the optimal environmental situation. The existence of the change just a few in the value aw or the pH could cause the increase in the temperature of the growth drastically. For example to be Enterobacter aerogenes that had the temperature of the minimal growth of 5 °C if the activity figure of his water was optimal that is above 0.97. In the value aw of his 0.955 growth stopped at the temperature around 20 °C, and in aw 0.950 growth stopped at the temperature 30. In the same micro-organisms test, the increase in the temperature of the minimal growth to 15 °C when the decline in the pH from the optimal pH happening happened 7 became 3.9. To several micro-organisms, the low temperature could also cause the activity enzimatik became intensive. Pseudomonas more often produced lipase and proteinase in the temperature under the optimum temperature of his growth. This could explain results of observation that showed that the change resulting from the work of micro-organisms in the foodstuff often happened although the number of micro-organisms did not exceed the number that was permitted.
In the exponential phase, micro-organisms were very sensitive to the low temperature, especially Enterobacter and Pseudomonas, whereas the bacteria Gram positive apparently more kept. The freezing more or less made micro-organisms damage. This damage could be reversibel and caused the death of the bacterial cell. This damage depended on the kind and the speed of the process of the freezing. The fast freezing with the temperature was very low not or only a little made damage of the bacterial cell, whereas the slow freezing with the temperature of the freezing relatively high (s/d –10 °C) could make damage great to the bacterial cell. This was supported in fact that the rate of the death of the bacteria increased with increasingly the increase in the temperature approached the point of zero. In a culture test was received by results that after being kept while 220 days in the temperature of –10 °C only remained at 2.5 % the bacterial cell that still was living, whereas that was kept in the temperature of –20 °C still was 50 % the bacterial cell that lived. In the temperature of –4 s/d – 10 °C the death rate was very high.
Nevertheless this could not be in practice used to eliminate micro-organisms to the foodstuff that was frozen because in this temperature micro-organisms psikrofil certain still could breed but also chemical reform still proceeding so as to influence the quality of the foodstuff. Knowledge concerning this process was important for reasons of along with: lethal micro-organisms broken was difficult to be found in the culture inspection bakteriologic. After this frozen foodstuff was heated and in the beneficial condition, this bacteria could come back beraktivitas so as as in the case of in the Salmonella case, could become the health threat of the consumer. Therefore, in the inspection mikrobiologik the foodstuff that was frozen (likewise to the product that dikeringkan or was heated), should use the method and the media that were suitable to be able to bring these broken micro-organisms back to life.

The high temperature
The control of micro-organisms through the treatment of the high temperature generally was carried out with pasteurisation or the sterilisation. Pasteurisation was the heating with the temperature under 100 °C and will not cause inaktivasi the microbe and the enzyme completely. Therefore the product that dipasteurisasi will not last long when being not accompanied by the treatment of the refrigeration or the other process factor like the change aw and pH. Sterilisasi was the heating that could cause inaktivasi the microbe and the enzyme so as the product could keep old.

The treatment of drainage
Drainage was identical to the reduction in the activity of water. In aw less than 0.70 growth of the cause agency of the infection and intoxication might not be worried again. To the product that dikeringkan, micro-organisms was in the situation “tidur” or in other words was in the phase lag that was extended. When the reconstruction happening (the absorption of re-water) then the available flora could in the foodstuff come back beraktivitas. Generally drainage was distinguished to drainage under atmospheric pressure and vacuum drainage. The special process was the combination between the freezing and the removal of water and or without the vacuum. Drainage was with air carried out in moving air, in drainage space that was heated, etc..

The treatment of the illumination
The dose of the illumination was measured with the unit Gray (Gy). The low illumination when his dose was less than 1 kGy, the medium when < 1-10 kGy, and high when more than 10 kGy. The scope of the process of the illumination (irradiation) was for the disinfection, the extending shelf-life, dekontaminasi and the improvement of the quality of the product. The profit that was obtained was the reduction as minimally as possible the foodstuff that was lost resulting from the process of conservation, and energy saving as well as the other profit. Beef that received the treatment of irradiation will cause the Psedomonas growth and Enterobacteriaceae really was hindered without causing the change organoleptik. Shelf life raw meat that was packed the vacuum could be extended. To pork, irradiation with the dose between 0.3 – 1.0 kGy could make inaktivasi Trichinella spiralis.

The treatment kimia
The normal treatment was carried out in part with giving of salt. Penggaraman this aimed at reducing the activity of water and salt personally did not have the influence antimikroba directly. The other treatment was with curing, that is the treatment by using kitchen salt and salt nitrit (natrium nitrit or potassium nitrit). This treatment could hinder the growth and the production toxin by Clostridium botulinum. The effect especially is decisive the length of the phase lag. The factor that influenced the effectiveness nitrit including the pH, oxygen, the other food component (the concentration of salt), the heating and irradiation. Fumigation also was one of the control methods of micro-organisms in the foodstuff by using the cold fumigation method, warm fumigation and hot fumigation. Pengasaman and the use of usual also preservatives were done by using materials that did not damage the health while being given with the dose that was exact for the aim of hindering the growth of micro-organisms.

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