There are many types of microorganisms that cause food spoilage. To sum up, there are mainly three types, namely bacteria, molds, and yeasts. Some people jokingly call these three fungi the three killers in food. The following briefly introduces the impact of three types of fungi on food quality.

1. Bacteria
In most cases, bacteria are the main cause of food spoilage.
The spoilage caused by bacteria is generally manifested as the spoilage of food.
Bacteria can decompose protein and amino acids in food, produce odor or peculiar smell, and even produce toxic substances, which can cause bag swelling of packaged products.
There are also some spore-bearing bacteria that have strong heat resistance and are widely distributed in the soil and air, which can easily cause pollution, and ordinary heating methods (heating at 100°C) cannot achieve the killing effect. At the same time, many spores have the function of producing acid and gas, which can also cause product deterioration and cause bag swelling.

2. Mold

Mold is mainly stored in a warm and humid environment, especially in a poorly ventilated state, it is easy to multiply. When the water content is less than 15%, its growth is inhibited, which is aerobic bacteria, and its activity can be completely inhibited in an anaerobic environment.
The optimum growth temperature of mold is 25-30℃, and its toxicity will be greatly reduced below 0℃ and above 30℃. Heating to 80°C for 20 minutes can kill most molds.
Foods rich in starch and sugar are prone to mold and mold growth.
Molds are widespread in nature, and their spores can float in the air. They are widely present on the surface of the human body, fingernails, respiratory tract, etc., which easily cause the growth of microorganisms that come into contact with products.
Most molds do not produce acid and gas.
Common molds are Aspergillus, Penicillium, Rhizopus, and Mucor.

3. Yeast

Yeasts are easy to grow and develop in foods containing more carbohydrates, such as various noodle products; but generally do not grow in foods rich in protein, such as meat products.
It grows well in a slightly acidic environment with a pH of about 5.0.
The heat resistance of yeast is not strong, and it can be killed at about 60~65℃.
Yeast generally does not produce acid and gas.
Yeasts are also facultative anaerobes. In anoxic conditions, yeasts decompose sugars into alcohol and carbon dioxide; under aerobic conditions, they decompose sugars into carbon dioxide and water.

Since most food production enterprises are carried out in open occasions, even some purification processing equipment does not meet the requirements of sterility, and the raw materials involved are of a wide variety of sources and have a wide range of sources. At the same time, equipment, personnel, and packaging are involved. There are many different factors such as materials. Therefore, the above three microorganisms that are widely present in nature can easily affect the quality of food. Understanding the growth habits of these microorganisms has a positive effect on the elimination of hidden problems caused by them.