Is freeze-dried fruit really a waste of money? In fact, everyone has wronged it...

A friend recently asked: Someone gave me freeze-dried fruit snacks , and my children fell in love with them as soon as they tried them.

It is said that fruits should be eaten fresh. Once processed, very little nutrition is left.

Even if dried fruits can still preserve dietary fiber and minerals, at least the vitamins and health-care ingredients are lost.

Is this freeze-dried fruit a waste of money? Can it really provide nutritional supplements if it is sold at such a high price? Is it considered healthy food to give this kind of snack as a New Year gift?

I said: If it is inconvenient to eat fresh fruit, or if you don't have enough, or if you have other concerns, you can still use freeze-dried fruit to supplement the nutrition of fruit. Of course, it is also delicious as a snack.

How are freeze-dried fruits made?

The so-called "freeze-dried fruit" is made by the "vacuum freeze-drying" process. Normally, drying food requires heating, so why can food be dried in a frozen state?

Anyone who has studied physics knows that water has a three-phase curve. In a frozen state, a small amount of water molecules will fly directly out of the ice and turn into water vapor. This change is called "sublimation."

The vacuum freezing equipment first freezes the fruit to a low temperature of minus 30 to 40 degrees Celsius, so that the food is covered with many tiny ice crystals. Then the air is pumped out to reduce the air pressure. The water vapor sublimated from the ice crystals is also continuously pumped out, so the ice-air two-phase equilibrium tends to produce water vapor.

In this way, the ice crystals in the food will continuously turn into water vapor at low temperatures. After dozens of hours, the food will become dry.

Because the ice crystals turn directly into steam and quietly leave the food matrix without passing through the liquid water state, many gaps are left inside the food, making it taste crispy.

This process requires both freezing and vacuuming, so it is very power-consuming and more expensive than other dehydration processing methods such as sun drying, hot air drying, infrared drying, microwave drying, and low-temperature frying.

However, there is investment and there are gains.

Freeze-dried fruit preserves nutrients

Vacuuming solves the problem that many nutrients and antioxidant ingredients are easily oxidized during processing. For example, nutrients such as vitamin C, vitamin A, vitamin E, folic acid, and antioxidant ingredients such as anthocyanins, flavonoids and carotenoids are all afraid of oxidation.

Low temperature freezing also solves the problem that some vitamins and phytochemicals are afraid of heat. As we all know, vitamins such as vitamin C, vitamin B1, and folic acid are afraid of heat. Health-care ingredients such as anthocyanins and glucosinolates are also afraid of heat.

Because it is not cooked, there is no loss of water-soluble healthy ingredients such as vitamin C, multiple B vitamins, anthocyanins, flavonoids, chlorogenic acid, etc.

Because there is no frying, there is no problem of loss of fat-soluble healthy ingredients such as carotenoids and vitamin K during oil dissolution.

Because it is dry enough to inhibit the growth of microorganisms, no preservatives are needed .

However, because there are many gaps, vacuum freeze-dried food is very easy to absorb moisture. If porous food is left at room temperature for a long time and comes into contact with oxygen, it will oxidize quickly.

Therefore, freeze-dried foods are usually placed in vacuum nitrogen-filled, light-proof and oxygen-proof packaging. They should be eaten quickly after opening the package .

When buying freeze-dried fruit, don’t confuse it with low-temperature fried fruit and vegetables

It should be noted that many people mistake low-temperature fried fruit and vegetable chips for freeze-dried fruit and vegetable products. In fact, they are completely different.

Low-temperature fried fruit and vegetable chips are produced by frying in a vacuum state. Vacuuming reduces the pressure, and according to the laws of thermodynamics, the boiling point of the oil will drop significantly at this time, even below 100 degrees Celsius.

This low-temperature frying method can greatly reduce the oxidative polymerization of oils and avoid the production of carcinogens such as benzopyrene. It also reduces the rate of the Maillard reaction, can well maintain the original color of fruits and vegetables, and also reduces the problem of fruit and vegetable aroma loss due to heat.

However, it is still a heating method that requires heating, which will inevitably cause the loss of vitamins. There is a lot of oil, and some carotenoids and chlorophyll will also be lost. Most importantly, low-temperature frying will greatly increase the fat content in fruits and vegetables.

Everyone knows that fruits and vegetables are classic low-fat foods, and the fat content of most fruits does not exceed 1%. However, once they are made into low-temperature fried "fruit crisps", the fat content can reach more than 10%, or even up to 30%, turning them into high-calorie, high-fat products!

Therefore, when purchasing dried fruits and vegetables, please keep your eyes open and read the ingredient list and nutritional information carefully.

Crunchy fruit and vegetable chips are not necessarily freeze-dried products . If the ingredients list contains the words "vegetable oil" and if the fat content in the nutrition facts list is high, then it is definitely not freeze-dried fruit, but a low-temperature fried product.

In addition, you should also check whether there are various sugars and sweeteners in the ingredient list. Unless some particularly sour fruits (such as sea buckthorn, sea buckthorn, lemon, cranberry, etc.) need to add a little sugar for flavoring, otherwise the ingredient list of freeze-dried fruits should only have "a certain fruit" as an ingredient . Such products have the highest nutrient density.

People with poor gastrointestinal function can eat

Vacuum freeze-dried fruits are more friendly to the stomach and intestines, solving problems such as "being afraid of cold when eating fruits before meals", "being afraid of cold when eating fruits in the morning", and "fruits hurting the stomach". At the same time, it also largely avoids the loss of nutrients caused by cooking fruits, as well as the extra sugar brought by cooking fruits.

For example, I have a sensitive intestine. After eating a fresh apple, I feel my stomach growling and my stomach sounds. Dried apples are also difficult to digest and make me feel uncomfortable because of their tough texture. But after eating one or two handfuls of freeze-dried apples, I don't have these problems.

One of the reasons may be that after freeze-drying, the dried apples form a loose and porous structure, which facilitates full contact with digestive juices and makes them easier to digest.

The second reason may be that after freeze-drying and storage for a period of time, most of the proteases in the fresh fruits are inactivated, reducing the damage to the mucous membrane on the surface of the digestive tract.

The third reason is that you don’t have to eat the whole freeze-dried fruit. You can eat a small handful or a small bag at a time. The total amount is limited, so it won’t cause trouble to the intestines.

Suitable for both big and small appetites

Here, I think of some complaints I often hear: "I have a small appetite, I can't finish a big Fuji apple in one go, and I can't store the remaining half." Others say: "I am too greedy, I can't stop eating all kinds of snacks, and I will get fat if I eat too much."

Freeze-dried fruit as a snack can solve these problems. Because each package of freeze-dried fruit is very small, and the price is relatively high, it is unlikely to be eaten in excess . Using small packages of freeze-dried fruit to replace biscuits, snacks, potato chips, etc. has much lower calories, is healthy, delicious, and can prevent overeating.

People who are busy at work can eat

"It's inconvenient to eat fruit while working" and many other problems. You can eat it right after opening the package, anytime.

It can be eaten all year round, and the nutritional value is very similar to that of fresh fruit. As a healthy snack, it is a very good choice. It is better than those fruit and vegetable crisps fried at low temperature, and much better than biscuits, cakes, potato chips, etc.

Can diabetics eat

Based on the research we've done on freeze-dried apples and freeze-dried dates, these products are relatively friendly to people with diabetes.

Take a look at the blood sugar curves made by our laboratory. The left picture shows the three treatments of jujube, and the right picture shows the three treatments of apple. The red line is fresh fruit (RJ, RA), the black line is cooked fruit (CJ, CA), and the yellow line is freeze-dried fruit (FJ, FA). It can be seen that the peak blood sugar level of freeze-dried fruit is the lowest, and the fluctuation range of blood sugar caused by freeze-dried fruit is even smaller than that of fresh fruit .

The glycemic index values ​​were calculated and found to be 65 for freeze-dried dates and 75 for fresh dates; 52 for freeze-dried apples and 51 for fresh apples. It can be said that freeze-dried fruits are safe for diabetic patients to eat (data to be published).

Some friends may ask: I heard that the GI value of apples is only 36? How come it has become 51? That’s because the apples tested back then did not have as much sugar and as little acid as the apples today...Sugar will increase the GI value, while organic acids and polyphenols will reduce the GI value. Now most fruit varieties are updated with more sugar, less acid, and less astringency, so the blood sugar response will naturally rise. Unfortunately, consumers just like this.

In short, freeze-dried fruit without added sugar is a good thing and is relatively healthy as a snack . Its main problem is that it is relatively expensive. Whether to choose it depends on whether you can eat enough fresh fruit and your perception of cost-effectiveness.