Do you need to cream butter and sugar when making a cake?

Can I melt butter with sugar in the microwave, instead of creaming it when making a cake? N. Lenehan

The magic of baking, for most cakes, happens when the gases trapped inside the batter expand during heating in the oven. While gases are created by the raising agents, such as baking powder, or the chemicals in the self-raising flour, air trapped in whipped egg whites, and - in answer to your question - creamed butter, also expands. This makes for a fluffy cake.

During creaming, when sugar and butter are beaten together, the sugar dissolves in the water in the butter and tiny air bubbles are trapped by the fat. You will notice that when you cream butter and sugar until light and fluffy, the mixture increases noticeably in volume. (When making denser cakes, such as a Dundee cake, one only creams the butter and sugar until creamy, otherwise there will be too much air in the mixture.)

If you melt the butter and sugar in the microwave, any air you beat into the mixture will simply float to the top and disappear.

How do I get my fish batter less stringy? G. Colvin

If you beat your batter too vigorously, the protein in the flour will come together to form long strands and this will make it stringy and less likely to stick to the fish. Beat your batter until smooth, then rest it in the fridge for a few hours prior to deep frying. To get a brown batter without overcooking your fish, add a teaspoon of sugar to every cup of flour.

Is it safe to freeze leftover lap cheong sausages? If so, for how long? S. Douglas

Chinese lap cheong is made with minced, spiced pork that has been stuffed into skins and allowed to ferment at quite warm temperatures. During this process lactobacillus bacteria ferment, causing sugar and naturally occurring lactose to form in the meat's lactic acid. This drops the pH of the sausage to a level where bad bugs struggle to exist, thus preserving the sausage.

In the days before fridges and chemical preservatives, sausages were stored in dry and airy sheds and cellars. Today's lap cheong are also treated with preservative and sold packed in plastic on Asian grocer's shelves. Once open, you can keep yours wrapped for several weeks in the refrigerator. Delicious served sliced and warmed as a snack, they add a sweet and fragrant note to fried rice and are lovely with stir fries. If you did want to freeze them, they will still be OK for about six months.

• 17 essential ingredients to discover in 2014: Lap cheong sausage

Why do you recommend not washing mushrooms? They grow in dirt and I don't want to risk eating dirt. Lana

A few weeks back we concluded that mushrooms needn't be washed or peeled, to which we received the above question. There was also this comment on the website: ''The myth of not washing mushrooms must be put to rest. Any water 'absorbed' is so minuscule it's not worth worrying about.''

These communications prompted further explanation and exploration. Firstly, mushrooms are not grown in dirt. They are grown in a substrate of compost, manure, organic matter such as straw and other material that ferments to a temperature that sterilises the growing medium. You can wash it off but mushrooms absorb water. I weighed both cup and Swiss brown mushrooms, washed them, drained them and then weighed them again and they had increased their initial weight by 10 per cent, presumably from water. This water ran out when we cooked them in a very hot pan and had to be evaporated off.

The washed mushrooms, compared with the unwashed mushrooms from the same batch, had less of a dark patina and more stewed appearance when cooked.

Letters

To a reference about the rich dessert Sussex Pond, S. Rosenberg replied, ''My recipe came from Margaret Costa's wonderful Four Seasons Cookery Book, recently republished by Grub Street. Can anyone help with a recipe for Hollygog pudding? I lost mine and my now adult children still long for another taste of it.''

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