Brain Food: How can I reduce the amount of fat in a cake?

Do you really want to reduce the fat content of cake?
Do you really want to reduce the fat content of cake? Photo: William Meppem

How can I reduce the amount of fat in a cake? C. Laszlo

Did you know that there are two proteins in wheat flour called gliadin and glutenin? They combine, in the presence of water, to form gluten. Fat, however, interrupts the formation of gluten by coating the proteins and stopping them from getting access to the water. If you didn't stop the formation of lots of gluten you would have something with a tough crust and spongy interior. Cake, by comparison, is moist and crumbly. Sugar also inhibits the proteins from combining by soaking up water. The food industry replaced fat with sugar in loads of food a while back hence lots of low fat but high sugar junk foods. You can reduce the amount of fat, that is, butter or margarine, by replacing it with one third the weight of fat with fruit puree. Add to the mixture after creaming the butter and sugar.

Can I eat purslane growing wild in my garden? G. Edmonson

I remember visiting the floating island farms of Lake Xochimilco in Mexico City. They are large plots of land floating on what was once a massive volcanic lake. Soil from the lake bed was dug up and plonked on top of the islands to create fertile soil. The islands were stopped from floating away by tree roots that tethered them to the shallow lake bed. I started kicking what I thought was a weed. The farmer called me "gringo estupido" and spat onto the dusty ground. I was kicking out his precious verdolaga. We call it purslane. Botanists call it Portulaca oleracea. It grows wild and spreads over the thin layer of rich topsoil in Xochimilco, stopping it from washing or blowing away. Mexicans prize this prostrate succulent for its health-giving qualities: it's high in magnesium and omega-3. If I were a betting man, I would have $1000 on this to be the superfood of 2017. Pick the new leaves on the tips and add them to a salad where they will bring a bit of crunch. Add the older leaves and stems to vegetable braises, where they will add a slightly sticky texture to the dish.  

Try King Edwards for the best baked potatoes.

Try King Edwards for the best baked potatoes. Photo: Eddie Jim

I am looking for a good all-round, white potato. P. Holmes

It's new potato season now and there are a few fantastic potato varieties hitting the shelves. For an attractive and flavoursome finger-like potato try Pink Fir – except it has a pink skin. For the best baked potatoes try King Edwards, except they have a pinkish blush on the skin. You can peel the purple skin off Blue Moons but their flesh is a little creamy. I know this is no help to you whatsoever but I am thinking of other potato loving readers. I personally love Wilwash. It is cross between Sebago and the world's most boring potato, Coliban. One that would make Bill Shorten look exciting. Wilwash is the beautiful child born of two dull parents. It is full flavoured,  mashes to a perfect cream, roasts light and fluffy and fries to golden perfection. Harder to find but try jonespotatoes.com.au. You can order online there.

Send your vexing culinary conundrums to brainfood@richardcornish.com.au or tweet to @Foodcornish