What are the pros and cons of food variation, and what are the factors that affect food spoilage?

You can go back to the second semester of the sixth grade and start from the previous one.

There are five main causes of food spoilage, namely microbial action, enzyme action, chemical action, and respiration.

and physical effects.

First, microbial action.

Microbial action refers to the deterioration of food due to the growth and reproduction of microorganisms in food.

Because food contains a lot of water and a variety of nutrients, it is most suitable for the growth and reproduction of microorganisms such as bacteria, molds and yeast. Microorganisms can secrete various toxic substances and enzymes in the process of life, which promote the decomposition of food and destroy the cell wall.

The high molecular material that penetrates into the cell becomes a low molecular substance. So the presence of microorganisms, especially spoilage microorganisms, is the main reason for the spoilage of food.

The destruction of food by microorganisms is related to the storage conditions of food, the type composition and the type of microorganisms, if the food has the conditions suitable for the reproduction of microorganisms, the microorganisms will multiply rapidly, so that the food deteriorates; If the conditions are not sufficient, then the multiplication of microorganisms will be slow, and the rate of spoilage of food will be reduced.

The survival and reproduction of microorganisms requires certain environmental conditions, such as gas, temperature, humidity, etc. However, temperature is the most important factor affecting the reproduction of microorganisms, and food can only be stored in an appropriate and stable low temperature environment to ensure quality.

Second, the role of enzymes.

The role of enzymes refers to the decomposition of food nutrients and the deterioration of food due to the fact that enzymes in the food itself can decompose the nutrients of the food under suitable conditions.

Enzymes exist in animal foods and plant foods, and can be separated from living cells to play a catalytic role, under suitable conditions, will promote the decomposition of protein, sugar, fat and other nutrients in food to produce hydrogen sulfide.

Ammonia and other unpleasant gases, and toxic substances are inedible.

The activity of an enzyme is temperature dependent. At low temperatures, the activity of the enzyme is very small, and as the temperature increases, the activity of the enzyme increases, catalyzing the chemical reaction.

The speed also increases, but above a certain temperature, it will be destroyed and inactive. Therefore, after the reaction rate reaches a certain peak, if the temperature rises again, the speed decreases, and the enzyme has the same temperature as the microorganism has the most suitable temperature, and the enzyme is the most active in a certain temperature range. If you lower the temperature, you can reduce the speed of its reaction.

Therefore, keeping food at the right low temperature can prevent spoilage due to the action of enzymes.

Third, chemical reactions.

Chemical action refers to the chemical components in food being oxidized by oxygen in the air and causing chemical reactions, resulting in food deterioration.

Both enzymes and oxygen cause and facilitate chemical reactions. For example, when grease comes into contact with air, a chemical reaction occurs to form acetaldehyde.

Ketones, acids, and other compounds increase the viscosity and density of the oil itself. There are some other food ingredients such as vitamin C

Natural pigments, etc., also undergo oxidation reactions.

Degrade and deteriorate the quality of food.

Food deterioration refers to the physical changes in the appearance of food, as well as the spoilage and deterioration that occurs under the action of microorganisms, including various enzymatic and non-enzymatic changes in food composition and sensory properties and contamination by inclusions, so that the food reduces or loses its edible value. Consumption of spoiled food can cause disease in the human body and is not beneficial to the human body. There are 3 main causes of food spoilage:

1. Microorganisms. Microorganisms are everywhere in the environment, and food is easily contaminated by microorganisms during production, processing, transportation, storage, and marketing. As long as the temperature is right, microorganisms will grow and multiply and break down nutrients in food to meet their own needs.

At this time, the protein in the food is destroyed, and the food will emit a foul and sour taste, lose its original toughness and elasticity, and the color will also change. 2. The role of enzymes. There are many enzymes in animal food, and under the action of enzymes, the nutrients of the food are broken down into a variety of lower products.

The rice and fruit rot that we usually see are because the carbohydrates are broken down by enzymes and fermented. 3. Chemical reactions of food. Fats are easily oxidized, resulting in a series of chemical reactions, and the oxidized fats have a strange smell, such as fat meat will turn from white to yellow.

Spoiled food not only changes its appearance, loses its original color, aroma and taste quality, but also reduces its nutritional value, and also contains corresponding toxins that endanger human health.

Do you have any questions?

I hope mine can help you, if you can, please give a thumbs up, thank you.

Questions. What is the reason for the bagged shortbread to be placed for a long time to absorb oxygen.

This is because the moisture in the oxygen invades the bag and causes it to react with it.

Different foods have different deterioration performances, mainly color, smell, whether there is rot, etc., green leafy vegetables must not be eaten when they turn yellow, and moldy food, do not eat the whole package.

Food spoilage is very common in life, and it also brings us a lot of troubles, if which kind of food is never.

It doesn't deteriorate, and it's much more reassuring to eat. Scientific research and practice have proven that honey, liquor, vinegar, sugar and salt are foods that do not spoil.

Honey: Freshly ripened honey that is a transparent or translucent gelatinous viscous liquid, with sugar accounting for the total amount of honey.

Above 3 4, the moisture content is low, and neither bacteria nor yeast can survive in honey.

In addition, honey contains: 4% bacteriostatin. Therefore, ripe honey is not easy to spoil if left for a longer time. But if it is not ripe honey or an inferior product that has been mixed with water, it will ferment and bubble after a period of time

Turns sour and cannot be eaten.

p;Under sealed conditions, microorganisms are not easily invaded and difficult to multiply, so they will never deteriorate. However, this does not mean that the longer the liquor is stored, the better, and the taste of ordinary flavor liquor will become weaker and the aroma will weaken after 5 years; Sauce-flavored aged wine is a good wine, while it is still inconclusive whether a strong wine that has been stored for many years is a good wine.

Vinegar: Vinegar has the effect of antibacterial and sterilization, and can be used for food preservation and preservative, such as acid ulceration. vinegar.

The shelf life is relatively long, but it is also affected by the process and raw materials. The brewing vinegar with better technology is sealed in a jar and placed underground, and the longer the year, the more mellow the taste.

Solid sugar: Solid sugar includes commonly used white sugar, cotton sugar, rock sugar, single crystal rock sugar, etc.

Solid sugar is not conducive to the growth of microorganisms due to the lack of moisture and strong osmotic pressure inside the structure, and it is difficult to be polluted. However, sugar is easy to absorb moisture, and if it is not placed properly and its properties change, it will be contaminated by microorganisms.

Table salt: The main component of table salt is sodium chloride, which is chemically very stable. As with table sugar, table salt.

It is often used to preserve food and is a natural preservative. However, if the iodized salt we often eat is not protected from light and high temperature, the iodine content will be reduced if it is left for too long, but the quality of the salt will not change.

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We all know that food should be thrown away when it is bad, and eating it is harmful to the body. However, it is difficult to tell whether some foods are good or bad just by looking at their appearance, but you can tell by smelling them, and even if the surface of the food is fine, you must throw it away!

Hara. Foods containing more oil are left for a long time, such as oil, cakes, dry pickled products of fish and meat, walnuts, peanuts, melon seeds, etc., which will produce a bitter and numb, pungent and unpleasant taste, which is commonly known as "hala taste" by the common people. This is because fats and fats are easily oxidized and rancid, which leads to the development of hala flavor.

The development of hala flavor is often accompanied by browning of color (e.g., the fatty part of bacon turns from white to yellow) and changes in food texture (e.g., pastries become dry and hard and unpalatable).

Therefore, this type of food should be stored in a sealed seal, protected from light, moisture and high temperatures.

Rancid smell. Spoilage of protein-rich foods such as fish, pork, eggs, tofu, and dried tofu can produce a rancid odor. This rancid smell mainly comes from the decomposition products of proteins and fats, and can cause human poisoning when consumed.

In addition to the rancid smell, the spoilage of this type of food is also manifested as sticky surface and green color.

Therefore, this type of food should be eaten in time after purchase, or put it in the refrigerator or frozen.

Ammonia smell. Foods such as fish, shrimp, shredded squid, and dried scallops that have been stored for too long will have a distinct ammonia smell and will turn pink in color. This is due to the fact that proteins break down into low-amine substances, which are very toxic, and should be thrown away as soon as this taste appears.

Acerbity. Carbohydrate-rich foods such as grains, sugars and their products will produce a sour or rancid taste with their own characteristics when spoiled. Carbohydrates break down to produce monosaccharides, disaccharides, organic acids, alcohols, and aldehydes, resulting in a sour or alcoholic taste.

Therefore, it is best to store this type of food in a dry and ventilated place.

Musty smell. Foodstuffs contaminated with mold, such as grains, peanuts, bread, cakes, rice, and steamed buns, often become moldy and spoiled in a warm and humid environment. Mold can produce toxins, such as the familiar aflatoxin.

Ammonia smell.

Food spoilage generally refers to the transformation of food into food that does not meet the requirements of hygiene due to the action of microorganisms due to the action of microorganisms under certain environmental factors. Such as the rancid smell of fish and meat, the rot of fruits and vegetables, the rancidity of oil, the mildew of grain, etc.

Generally speaking, fish, meat, fruits and vegetables have the most obvious effect of bacteria, while grains and flour products have the most significant effect of mold.

Fish and other foods mainly produce bad odors, sticky surfaces, discoloration, tissue water, etc.; Milk will clump, fruits and other mainly surface rot, some watermelons and so on will become rancid, and pastries such as bread are mainly moldy spots, and if they are left for a long time, they will be drawn.

To be precise, it should definitely be advantageous, not sure whether there are disadvantages or not, and there may be risks. See the answers to the above two for details. Another scientific and technological achievement is attached to let you know what the risk is, you can take a look at it in detail:

Professor Zhang Chenyu of Nanjing University confirmed that microRNA enters the human body through plant food, and the significance of this research is as follows:

1) The food people eat may directly regulate gene expression in people's bodies.

2) Exogenous plant microRNAs inhibit the expression of certain proteins in mammals, including humans, such as plant miR168A inhibits the expression of LDLRAP1 protein in mammals, increases the levels of LDL and cholesterol in the blood, thereby increasing the risk of metabolic syndrome, which provides the possibility for the development of new strategies based on exogenous microRNAs to enhance or inhibit the expression.

3) These results contribute to a better understanding of how specific components in food regulate health and disease.

4) MiR168a may be just one example of many exogenous plant microRNAs, and it will be found that more exogenous plant microRNAs are able to cross the gastrointestinal tract and have an impact on host physiology.