Pre-planning
The 2005 class was given the issue to develop a unique 'Kiwi' bread that reflected New Zealand culture or 'Kiwiana'. They began with researching and making paraoa (Māori bread) with rewena (potato leavening) before looking at different breads from a variety of cultures.
Rewena paraoa has only a small niche market in New Zealand; so Marietjie asked her class to develop a recipe suitable for mass production. Students also made a variation of rewena paraoa, using urenika , a variety of Māori potato.
Some students concentrated on the purple dough they achieved through using purple potato, and made purple-coloured bagels; while another based a recipe on Portuguese potato bread combined with rewena. Shape was another focus and bread was made formed as a koru, rugby ball and other New Zealand symbols, while other students looked at additional ingredients, such as sprinkling kawakawa herbs on top.
While trialling recipes one group had made rewena with urenika; when the bread was removed from the oven it was completely green. Everyone was very excited about this and tried to duplicate the recipe but couldn't. Neither students nor Marietjie knew what had caused the bread to go green. At one stage they put grated green apple into the starter and for a while thought that was causing the green bread. Time constraints meant that the class did not follow up this discovery. They wanted to use green bread for a bun in a hamburger competition, but had to use spinach to achieve the colour.
During the 2006 unit Marietjie challenged two students to investigate why the bread went green. After doing research on the internet and experimenting with making the bread, they visited Dr David Weatherburn, senior lecturer in chemistry at Victoria University, and talked to him about their work.
He told them of an article that appeared in 'New Scientist' magazine (July 2006) that discussed an incident where a teacher had done an experiment on red cabbage and egg white, when the egg whites turned green. This is a result of the presence of anthocyanins in the purple cabbage and the alkalinity of the egg white.
He then had the students look at their recipe and identify which ingredients were alkaline and acid. (He pointed them towards the baking soda, which works with the anthocyanins in the urenika; when the mixture is heated up the dough comes out green).
The boys worked hard to perfect the recipe and eventually succeeded. Marietjie recalls teaching in another room when the boys rushed in: "Miss, we did it!" This breakthrough laid the groundwork for other students to do further work on green bread in 2007.
