Why the kale season only begins after the first frost has come
The car windows freeze over and ice crystals decorate the trees. The kale season in Northern Germany begins always after the first frost has come. But why is that so? Though chefs from Northern Germany know, that kale simply tastes better then, there has been no scientific answer to this question, yet. However, Professor Nikolai Kuhnert of Jacobs University Bremen and Professor Dirk Albach of the University of Oldenburg, have now found an answer to this question together with their working groups. The findings were published in the journal “Food Research International”.
The researcher exposed three different kinds of kale to normal and cold temperatures in Oldenburg. Subsequently, the kale leaves were examined for its ingredients in Bremen. At cold temperatures, the plant transforms complex carbohydrates in its cell walls into
smaller sugar molecules, all of which are sweet and make the kale taste better. Plants, which were previously exposed to cold temperatures, contained elevated concentrations of sugar, especially fructose, melibiose, maltose and raffinose.
Why does this happen to the plant? The plant benefits from so-called colligative properties of sugar. These are based on the number of particles in a solution. In the case of kale, it causes the freezing point to be lowered. To prevent the water in its cells from freezing, it increases the number of particles in the cells. Complex cell wall carbohydrates are transformed to many sweet sugar particles, which protect the cabbage from frost. The same phenomenon can be observed when salt is spread in winter. A large number of salt particles lower the freezing point of water, the ice melts after scattering and one won’t slip.
About Jacobs University Bremen:
Studying in an international community. Obtaining a qualification to work on responsible tasks in a digitized and globalized society. Learning, researching and teaching across academic disciplines and countries. Strengthening people and markets with innovative solutions and advanced training programs. This is what Jacobs University Bremen stands for. Established as a private, English-medium campus university in Germany in 2001, it is continuously achieving top results in national and international university rankings. Its more than 1,500 students come from more than 120 countries with around 80% having relocated to Germany for their studies. Jacobs University’s research projects are funded by the German Research Foundation or the EU Research and Innovation program as well as by globally leading companies.
For more information: www.jacobs-university.de
Facebook | Youtube | Twitter | Instagram | Weibo
Prof. Nikolai Kuhnert (Jacobs University Bremen): email@example.com
Source: Food Research International, 2020, 127, 108727