26 August 2019
A meat stall at a Chinese wet market. The age of an animal has a great impact on the quality of meat products. Photo: Reuters
A meat stall at a Chinese wet market. The age of an animal has a great impact on the quality of meat products. Photo: Reuters

Things you should know about food quality

The quality of food refers to the nutritional value and the eating experience, which includes its color, aroma, taste, and texture.

The quality could be affected by the composition of the food, such as water, carbohydrates (sugar and starch), protein, fat, fiber, minerals, vitamins, and beneficial or harmful substances.

The composition of food depends on such factors as the sex, age, genes, and parts of the animal as well as the season.

Age has a great impact on the quality of meat products. Young animals have a relatively higher water content and less fat, resulting in softer and less chewy meat with a slimy texture.

As they grow older, their bodies would contain less water, more protein, and substantially more fat, thereby improving their nutritional value and texture.

When an animal is slaughtered for meat, their muscles would tense due to stress and their meat would be firmer.

After some time, the enzymes in their body become active and decompose the proteins. As a result, the flesh would begin to relax, but its water-holding capacity and the taste of the meat would increase slightly.

When pork starts releasing liquid, it does not necessarily mean that it is no longer fresh. When an animal gets nervous, its body turns glycogen in the muscles into lactic acid, which in turn tightens the muscles and drains the stored water. When the muscles loosen up, this will disappear.

Red meat contains a protein called myoglobin, which has an iron structure similar to hemoglobin found in red blood cells.

When the iron structure combines with oxygen, it is bright red. When oxygen is lacking, it turns into a darker red. When heated, the iron oxidizes and appears brown. The higher the temperature, the darker the color.

In general, bacteria and viruses can be killed by heating the food to 70°C or above for about five minutes.

However, certain toxins produced by bacteria within the food, such as ciguatoxin in fish and alkaloids in poisonous mushrooms, cannot be decomposed by heat. This results in food poisoning.

That’s why people should be careful when buying food or ingredients.

This article appeared in the Hong Kong Economic Journal on June 6

Translation by John Chui

[Chinese version 中文版]

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