Does honey ever go off?

I was led to believe that honey is a food that can't go off. G. Harmon

"Imagine entering a townhouse which had been closed for the summer," wrote Arthur Weigall in The Glory of the Pharaohs in 1923. The tomb of royal parents Yuya and Tjuyu in Egypt's Valley of the Tombs of the Kings at Thebes had just been opened and the author recalls stepping inside. In the tomb was found an alabaster jar of honey, still in its liquid state. Honey, if stored in a sealed container, can remain in good condition for thousands of years. This is because bees take sweet nectar from flowers and digest it. In their stomachs an enzyme called glucose oxidase breaks down the nectar into gluconic acid and hydrogen peroxide. This makes honey quite acidic and the hydrogen peroxide stops yeasts and moulds growing. The bees also reduce the water content of the honey by fanning it with their wings. Such a concentrated solution of sugar retards the growth of bugs. So if sealed, this concentrated form of natural sugars doesn't go off. If you take the top off the jar, however, the honey will start to suck in moisture from the atmosphere. This dilutes the honey and can allow the growth of microbes. If diluted honey is inoculated with certain strains of yeast, it ferments into alcohol, producing mead.

How should I store my summer fruit? P. Shepherd

Ripeness, like beauty, is in the eye of the beholder. My Calabrian friend Sammy says Aussies eat our fruit far too sweet. He comes from a long line of people who would pick their fruit just under-ripe so the "bloody birds wouldn't get them". The sweetness that comes from ripening occurs as starches are turned into fruit sugars. Stonefruit such as peaches and nectarines from the supermarket will be quite hard – they couldn't be transported if they were soft. Stored in the fruit bowl they will ripen at room temperature. Once ripe they can be stored in the fridge. The same goes for apples, pears and mangoes. Unripe mangoes can be kept in a paper bag to help ripen. Some fruits should not be refrigerated. Bananas and the novel and delicious achacha, originally from Bolivia, go brown if stored in the fridge. If you have achacha, store them in a sealed container at room temperature.

Can you please explain the need to place a paper napkin under plates in restaurants. K. Elder

I used to work in a cafe in the 1980s when paper doilies were placed over paper plates to make the quiches served on them look posh. This effect was somewhat diminished when a slice was taken from the tomato quiche and the torn, wet doily was covered with coagulated egg and tomato pulp, making the whole thing look quite Quentin Tarantino. Paper napkins, or serviettes, are layered between the plate or bowl from which one eats and the plate the waiter handles underneath it mainly to add some friction. White plates on white plates tend to move around when hurled around a busy dining room and the paper napkin acts both as a brake and shock absorber, and in, violently busy establishments, a sponge.

Letters

Recently J. Fisher wrote, "My grandmother claimed she could 'hear' when her cakes were ready. Is there any science in this?" Scores of readers responded, including V. Benson-Hodge, who wrote: "I am well into my 70s and was taught to cook by my mother in the country. I used to make wedding cakes that I slowly baked for many hours and the most accurate way to tell when the cake was cooked was to take it out of the oven and put your ear to it. If it was still hissing or crackling then it was not cooked." Apparently the moisture escaping from the uncooked batter makes a hissing sound. This ceases once the batter inside is cooked.

If you have a vexing culinary query email brainfood@richardcornish.com.au or tweet to @Foodcornish