• Recipe collection: 30 avocado recipes that are better than guacamole
• Adam Liaw's avo shichimi recipe

How do I stop avocado from going brown after cutting open? K. Mullins

Once cut, avocados don't improve with age. Use them straight away. You can mash the flesh, mix in a little lemon juice and freeze. The browning is caused by an enzyme called polyphenol oxidase. By stopping air getting to the exposed flesh, you will slow down the enzymatic reaction. Cover the cut surface tightly with plastic film or brush it with olive oil. Covering the cut surface with lemon juice will deactivate the enzyme. Store cut avocados in the fridge.

Is the white mould that grows on the outside of salami dangerous? M. Purcell

Moulds are used to produce all kinds of delicious things, from cheese and sake to miso and soy sauce. Traditionally, foods such as cheese would be naturally inoculated by moulds that were indigenous to their environment. The story of roquefort cheese, for example, tells a tale of a lusty French shepherd leaving his sheep's milk cheese lunch in a cave to follow a beautiful young country girl. He returned from his bucolic cavorting weeks later to find the cheese had turned blue, due to a mould, Penicillium roqueforti, that naturally occurs in the caves of that region. Another cheese, camembert, is covered by a white velvety mould called P. camemberti, which protects the rind, helps break down the interior and gives the cheese its mushroomy aroma. This same mould is added to some smallgoods, along with other moulds and lactobacillus. The lactic bacteria create lactic acid, which helps make the salami too acidic for bad bacteria to thrive and gives salami its sour tang. As the moulds grow, they add flavour, and the white mould on the exterior slows down the rate the salami dries out. Not all salamis use white mould. Some salamis are encased in white plastic to emulate the mould. The mould is perfectly safe to eat, although you should peel away the salami casing before you slice off what you are going to serve. Wrap the remaining salami and put it back in the fridge.

When boiling veg, which ones go into boiling water and which ones do you start in cold water? J. Burke

Drop a potato into boiling water and the outside will cook but the centre will be as hard as a brick. So start dense, heavy vegies such as carrots and potatoes in cold water, because as the water warms, the veg absorbs the heat and begin to cook evenly. Leafy greens, fresh legumes (green beans, peas) and cucurbits (pumpkin family) should be lowered into boiling water. Remember that latent heat will continue to cook the vegetables long after they are removed from the boiling water, so if you're cooking beans or peas for a salad, consider refreshing them in iced water to stop them cooking to a soft mush.

Letters

Recently we discussed rescuing split mayo by adding hot water, starting again using a new egg yolk or mixing with store-bought mayo. R. Sweet responded with: "You have led your readers into a world of pain. I was there too, until I discovered the stick blender method of putting all the ingredients into an old-fashioned milk shake container, putting the blade to the base of the container and blending on high. Stop. Lift the device. Return to the bottom of the container and repeat. Perfect mayo every time."

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