Are all nutrients lost in jam?

Answer

Dear Sophie,

Certainly not all nutrients are lost in jam! Jam is naturally made after a fairly long heating at a higher temperature. I think it is obvious that components that are heat-sensitive are broken down. The most relevant in this regard seems to me to be vitamin C. This is an oxidation-sensitive molecule and the oxidative degradation accelerates at higher temperature. I don’t know if there are concrete figures, but I wouldn’t consider jam as a relevant source of vitamin C.

In principle, minerals themselves cannot change much: calcium remains calcium, potassium remains potassium. What can happen is that the bioavailability changes. Bioavailability is the extent to which our body is able to absorb nutrients from our food. After all, some of the nutrients present cannot be absorbed. This is the case with minerals, for example. These can be bound to certain components so that they are not absorbable and actually leave our body through the feces. Due to the heating, certain cell wall components in the fruits will be broken down, which in my opinion can increase the bioavailability of minerals, among other things. Other cell wall-bound nutrients may also become more readily available. This is known with beta-carotene, but this component is perhaps less relevant for current jams I think.

As for the fibres. Fiber is actually that part of the food that is not digestible for us and ends up in the large intestine: this is the last compartment of our digestive system. In this large intestine, these fibers undergo a fermentation process, so that nutrients can still be released for the micro-organisms present and some for us. The name fiber in itself has nothing to do with a fibrous structure, just to be clear: it is sometimes wrongly thought that chopping food into pieces reduces the fiber content. This is not right! The cooking process will certainly have an effect on the fibers of the fruit: this is also the basis of making jam: something changes in the so-called pectins – this is one of the components of the fiber fraction, which makes the jam gel. . However, the impact of these changes on the digestibility and absorbability of these components seems nil to me: in other words, these modified components also end up in the large intestine where they will be fermented.

So as stated at the beginning: not everything is lost.

Regards

Bruno De Meulenaer