How does temperature affect thefood spoilage?

Blogger: Kural's Food Safety and Quality
Link: http://kuralvasan.blogspot.ae/
Temperature and food spoilage: 
How does temperature affect food spoilage?

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Kural Vasan Ramakrishnan, Food Safety Officer, GHP Quality Consultants, Dubai, UAE.
email: kuralvasan@gmail.com  mobile:+971 50 6555683

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Food production chain:

Temperature is an important factor which can influence the food spoilage. The food production and supply chain is too length and its starts from the farms and end-up with plate. In every step of the process appropriate temperature should be maintained to avoid the food spoilage. Temperature violations will affect the quality of the food supply chain; like food production, transportation, storage, processing, cooking and serving. For example the agriculture food items are produced by farming and its travels many transportation channels to reached the market by land, air and water ways. The food transportation includes local supplies, national supplies, export to other nations and imports are takes a day to few weeks of time to reach the market. 

Food are derived from agriculture, sea sources, forest/ nature and from some other sources.For example agricultural products to be stored in suitable condition and temperature to avoid the spoilage of the product. Why food spoilage mostly running around the temperature? Violation of temperature makes favorable condition for many microorganisms like bacteria and molds to grow in the food.

Food Spoilage microorganisms can be classified based on the food spoilage. 1.Pathogenic/Disease causing microbes example Salmonella sp causing typhoid fever. 2. Non-Pathogenic microbes 

(Not causing disease/ some favorable microbes) example Lactobacillus sp for the milk fermentation and yeast for producing spongy texture in bread baking.

Figure 1: Food production and supply chain

Food Market:

Food supply chain has being controlled and screened by government authorities like food departments, municipalities etc., Food items which is available in the market are concerned to met the local body regulations, government food code or international standards. In  the super markets/hypermarkets we can see the properly identified, food labelled, temperature maintained and arranged food items in display. Consumer should buy only the required food items, excessive buying some times may leads to food wastage. Landfill food waste are a  cause for the environment impact as well as it may hurt the economy of the buyers.

Food production and distribution are regulated and monitored by various quality bodies and regulatory agencies etc. In the food supply chain they are the one; responsible to ensure the food safety and quality until to reach the market. But when a consumers pick the food item in to their home, consumer also responsible to ensure the food safety.

Figure 2: Food Market.

Food safety is consumer responsibility too:

If a quality food in not stored in proper temperature; it will be spoil easily and may leads to health risks.

At home consumer is responsible to store, cook and hold the food in correct temperature and hygienic manner. Every food consumer is responsible ensure safety of their food. Consumer should aware of the food safety and buy the good quality products as per the basic evaluations like labeling instructions, storage condition, package condition and physical appearances etc., Food safety the choice of consumers at home.

How does temperature affect food spoilage?

For example, if a tomato is intact with the plant; it would be protected by the plant and nature. Once we cut the tomato and put in to the collection basket then our responsibility is started to save the tomato from the spoilage, in particularly from temperature misuse. 

How to protect the tomato from the spoilage until getting used?

A harvested tomato may reach the consumer's hand within a or few weeks of time. It’s a challenge for the traders to protect the food from spoilage. Tomato should be stored in chilled condition to maintain the temperature.So that it can be little postponed fruit repining and bacterial contamination as well.

  Figure 3: Tomato 

At room temperature food can be spoiled easily; because it’s a favorable condition for  many microorganisms like bacteria and molds. In the ambient temperature water molecules of the tomato will be in free state. High water content (aW=Available water ) foods will be easily spoiled by bacteria at room temperature. But in case of chilled or frozen condition water molecules are inactive/freezes.

Many disease causing bacteria can not be multiply at extreme cold and will die at very high temperatures. In general most of the food spoilage bacterial pathogens grows at +37°C optimally. Bacteria survives at refrigerator temperature and minimal bacterial growth occurs in stored food items. In the freezing condition bacteria survives but multiplication will be stopped. It would be extend the food spoilage.

Food storage temperature:

Once the food item purchased from the market it should be stored  generally in three different temperature range.

1.Ambient/Dry storage  at 20-25°C and RH-45-60%. (Some times product temperature will be determined based on the quality issues. Chocolates are stored at +12 to 20°C.)

2.Chilled storage at 1 to 5°C (in refrigerator)

3.Frozen storage at -18°C (in freezer)

Figure 4: Food preparation cycle at home.


The above cycle is mentioning about the general food preparation

cycle at home with required temperatures.

Ready to Eat foods:

Some of the food items are ready to eat like fruits and vegetable. But it should be washed, cleaned and preferably sanitized with chlorinated water (25-50ppm) before use. 

Cooking:

All the food items should be cooked at 75°C and above. Particularly raw meat,beef and poultry items should be always checked for the internal temperature using a thermometer or by any other slandered experienced ways. But mostly at home thermometer check is not followed. Cooked chicken/meat are confirmed by its tenderness, cooked at high flame for at least more than 30 min. In case of any suspect about the cooked temperature  thermometer is recommended to use to check the temperature. 

Figure 5: Cooking

Danger zone (6-60°C):

Bacteria can multiply rapidly at 6-60°C, hence its called as danger zone for the food items.

Above 60°C bacteria can start to die; so its a suitable temperature for hot food holding. At 75°C and above bacterial cells get ruptured leads to die, hence the foods are recommended to cook at 75°C and above. 

Figure 6: Germometer 

Temperature between 1-4°C bacterial multiplication will be very slow and bacteria are alive. This stage bacteria awaiting for the favorable ambient  temperature to grow-up. Its recommended to monitor the refrigerator/chiller temperature should not exceed more then +5°C. Some of the bacteria are called psychrophiles which can grow at lower temperature.

Figure 7: Microbial growth at various temperature.

Cooling :

Some times cooked foods are left at room temperature for long time due to cooling purpose. Long time storage (more then 4h) may lead to bacterial multiplication. Cooked foods can be stored up to 4h or less based on the nature of the food. For example rice and chicken curry. Its not good idea to store for long time in room temperature it may lead to bacterial contamination and multiplication.

Storage of leftover foods:

Left over cooked foods should be stored in refrigerators (1-5°C) at least one or two days depend on the shelf life of the food. During  storage bacterial growth will be minimal and bacteria are alive. Recommended to store foods are reheated before use.  

Reheating:

Chilled storage food can be reheated at 75°C and more to avoid the bacterial survival. Chilled storage will be minimally allow the bacterial grown. Bacteria will be killed by reheating at high temperature. Reheated food is not allowed store again in the refrigerator. Cooking -Cooling- Storing-Reheating order should be followed always.Reheating can be done using microwave oven, electric hot plates  or by flame, but the  internal food temperature must be reached above 75°C to avoid the bacterial survival.

Serving:

All the hot served foods should be maintained at 60°C and above  before serve. Reheated food items should be served immediately or should be maintained at hot holding temperature. Storage of food items for more that 4h at room temperature may allow the  bacterial multiplication. If any  delay serving then food can be hot holds at  60°C.

 Figure 8: Serving

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Blogger: Kural's Food Safety and Quality

Link: http://kuralvasan.blogspot.ae/