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Kale: That's why it tastes better after the frost

Kale: That's why it tastes better after the frost



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Kale begins after the first frost - why?

Most cooks are well aware that kale only tastes good when it gets the first frost. This knowledge comes from empirical values ​​that have emerged over the years. The exact reason behind it has so far been unclear. A research team has now solved this riddle.

Researchers from Jacobs University Bremen and the University of Oldenburg found a scientific answer to the question of why kale simply tastes better after being exposed to frost. The results were recently published in the journal Food Research International.

Sugar from frost

The research team exposed three different types of kale to normal and cold temperatures. The researchers then examined the leaf material for its ingredients. It turned out that the ingredients of the leaves differed depending on the temperatures they were exposed to. In the leaves that experienced frost, complex carbohydrates in the cell walls were converted into sugar molecules.

Frost makes the kale sweeter

To be more precise, the frost ensures that fructose, melibiose, maltose and raffinose sugar are formed in higher concentrations in the kale. Due to the sugar formation, the kale tastes sweeter and is felt by most people as more pleasant in taste.

Why does kale produce sugar in frosty weather?

The scientists also found out what this mechanism is good for. The plant strives not to freeze the water in its cells in order to withstand lower temperatures. In order to achieve this, kale takes advantage of the so-called colligative properties of sugar.

Why don't sugar solutions freeze so quickly?

The principle of colligative properties means, among other things, that material properties in solutions (such as the freezing point) change as soon as the number of particles changes. It does not matter what kind of particle it is. Kale breaks down long-chain complex carbohydrates into smaller sugar molecules. The number of particles is increased, which changes the chemical potential and lowers the freezing point.

A principle often used by humans

The researchers compare the process to a process that we often use in winter: the spreading of salt. If we sprinkle salt on roads and sidewalks, the number of particles in the water content increases. This lowers the freezing point, the ice melts and you can no longer slip on it. (vb)

Author and source information

This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.

Graduate editor (FH) Volker Blasek

Swell:

  • Roberto Megías-Pérez, Christoph Hahn, Ana Isabel Ruiz-Matute, u.a .: Changes in low molecular weight carbohydrates in kale during development and acclimation to cold temperatures determined by chromatographic techniques coupled to mass spectrometry, Food Research International, 2019, sciencedirect.com
  • Jacobs University: Why the kale season only begins after the first frost has come (accessed: November 29, 2019), jacobs-university.de



Video: Growing Kale from Sowing to Harvest (August 2022).