Does over-mixing cake batter make the texture tough?

My mother told me that over-mixing cake batter can make the texture tough. Why? R. Cresswell.

Your mother was completely correct. When you add liquid to flour the water allows the proteins to uncoil and start to form bonds. When you mix the batter together you are allowing oxygen in the air to help those bonds strengthen to form strands of gluten. Gluten is a composite of different proteins that gives doughs and batters their elasticity and hardens when cooked, giving baked goods their structure. If you work your cake batter too much you will create very strong strands of gluten, something desirable in crusty, crunchy and springy bread but not something you want in a delicate sponge or soft tea cake. Gotta love mums. Where would we be without them?

I often hear chefs using "rapeseed oil" on cooking shows on pay TV. What is it? M. Todd

Pay TV is a collection of obscure 1990s sitcoms and documentaries about Sherman tanks repeated ad infinitum. Rapeseed oil is extracted from the rape plant. This is a brassica, and related to mustard and cabbage. The word "rape" comes from the Latin rapum or turnip. You may have heard of the Italian vegetable cime de rape or "tops of turnips". Back in the 1950s there was concern that rapeseed oil contained erucic acid, a fatty acid known to cause heart disease, and it was banned from human use in the United States by the FDA. The oil also contains glucosinolates, compounds that protect plants from insect attack and cause the pungent aroma and taste in brassicas. In the 1970s, Canadian plant breeders came up with a new variety of rape that contained much less of these two substances. They called it "canola", a neologism based on the words Canadian oil, low acid. Rapeseed gained popularity again in Britain earlier this decade with proponents arguing its high levels of beneficial vitamin E and plant sterols outweighed the risk caused by erucic acid. Cold pressed, single estate and unfiltered brands of rapeseed oil became Britain's answer to extra virgin olive oil. That is the rapeseed oil generally referred to on cooking shows. (See also our cover story on oils)

How do I stop my red cabbage from losing its colour? A. Lim

Shortly after you slice the cabbage dress it with an acidic dressing such as vinaigrette or lemon juice and then oil. The acid will help the anthocyans in the cabbage keep their red colour.

Letters

Recently we put the call out for ways of preparing kohlrabi.

R. Uren says that her son calls it "yummy veg". She grates it and cooks it in a pan with "heaps of butter, salt and pepper" then serves it with plenty of parmesan cheese.

Reader C. Williams sautes a finely chopped onion and two crushed garlic cloves in olive oil for a few minutes then adds an entire kohlrabi, grated, and cooks this for five minutes, stirring occasionally. Meanwhile, she beats together three eggs in a medium bowl then adds the slightly cooled kohlrabi and mixes before pouring the mixture into a buttered casserole dish. She tops this with fresh breadcrumbs, grated parmesan, chopped parsley and pepitas then bakes in a moderate oven for 25 minutes or until the crust is golden.

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