World Of Materials

Food spoilage is caused by microorganisms such as bacteria and fungus (mould).

Characteristics of spoilt food:

1. has unpleasant smell. 有难闻的气味
2. has unpleasant taste 味道改变了/ 有酸味
3. shows change of colour 颜色改变了
4. shows change of texture 弹性改变了
5. mouldy and / or slimy 发霉 / 有粘液

Conditions that suitable for the growth of microorganisms
1. airy place 空气的供应
2. humid place 潮湿的环境
3. enough nutrients 足够的营养
4. suitable temperature - 5 C to 65 C 适当的温度
5. suitable acidity / pH lever 适当的化学性质
6. not brightly lit / dark place 适当的光线

Food poisoning
Food poisoning occurs when food contaminated with organisms is ingested. The bacteria Staphylococcus aureus can commonly be found on people, but when allowed to grow in food this bacteria can produce a toxin that causes illness such as vomiting and diarrhea. Proper hygiene and hand washing can prevent this bacteria from entering food that will be eaten.The major source of Escherichia is from the feces of infected animals. It can also be found in untreated water. Cooking at the right temperature is important in eliminating this bacteria when it has contaminated food.

Food Poisoning Symptoms
Symptoms of food poisoning depend on the type of contaminant and the amount eaten. The symptoms can develop rapidly, within 30 minutes, or slowly, worsening over days to weeks. Most of the common contaminants cause:
  • nausea 令人作呕
  • vomiting 呕吐
  • diarrhea 腹泻
  • abdominal cramping 腹痛
  • fever  发烧                                                                                                                                                                                                                                                      Usually food poisoning is not serious, and the illness runs its course in 24-48 hours. 
abdominal cramping 腹痛

nausea 令人作呕 and vomiting 呕吐

diarrhea 腹泻

fever  发烧

 For more information :

Food preservation
Because food is so important to survival, food preservation is one of the oldest technologies used by human beings. In this article, we'll look at all of the different preservation techniques commonly used today, including:
  • Boiling  煮沸
  • Cooling  冷藏
  • Freezing  冷冻
  • Canning or bottling 罐装 / 瓶装
  • Drying 干藏
  • Dehydration 脱水法
  • Salting 盐腌
  • Pickling 腌制 (糖、醋)
  • Pasteurizing 巴氏杀菌法
  • Fermentation 发酵法
  • Vacuum-packing 真空包装法
  • Smoking  烟熏
  • Waxing  上蜡
The basic idea behind all forms of food preservation is either:
  • To slow down the activity of disease-causing bacteria
  • To kill the bacteria altogether
I­n certain cases, a preservation technique may also destroy enzymes naturally found in a food that cause it to spoil or discolor quickly. An enzyme is a special protein that acts as a catalyst for a chemical reaction, and enzymes are fairly fragile. By increasing the temperature of food to about 150 degrees Fahrenheit (66 degrees Celsius), enzymes are destroyed.
A food that is sterile contains no bacteria. Unless sterilized and sealed, all food contains bacteria. For example, bacteria naturally living in milk will spoil the milk in two or three hours if the milk is left out on the kitchen counter at room temperature. By putting the milk in the refrigerator you don't eliminate the bacteria already there, but you do slow down the bacteria enough that the milk will stay fresh for a week or two.


  1. how about to add some more notes like what are the bad results to human of taking the spoilt food, how we can reduce or prevent food to be spoiled easily....

  2. ok. Please give me some time to complete it. Thanks.

  3. What a wonderful job you had done! I like the ideas of giving the meaning of some important facts in Chinese. Sure this will be a greatful help for the pupils in Chinese school to understand the whole topic. And the add-on certainly also wuill the viewers to know where to get more information to further their interest of the topic. Well done!!!!

  4. Clear explanations with suitable pictures,very good!