Plastic containers: How long is too long?

SAFETY ALERT: Plastic containers may be convenient but watch out for signs of wear and tear.
SAFETY ALERT: Plastic containers may be convenient but watch out for signs of wear and tear.

When should I throw out my plastic microwave containers? S. McKinnon

A hippie friend, who doesn't have a lot of time for microwave ovens, once described mine as Satan's Hotbox. He was referring to the way that some additives used in making plastic containers migrate to food.

This happens at high temperatures, and fatty foods are particularly capable of absorbing these compounds.

The CSIRO suggests that one should discard plastic microwave containers "when the surface shows any signs of breaking down".

It also advises against letting plastic film come into contact with food and to not use ice-cream or margarine containers in the microwave as the ''low-melt temperatures of these plastics may result in migration of undesirable contaminants into the food or in physical disintegration of the containers themselves". Enjoy your microwaved mini-sub pizza for one.

What do I use instead of wheat flour to make gluten-free gravy or cheese sauce? P. Prentice

It's all about starch. This is the stuff that plants make to store energy. Flour is about 75 per cent starch and about 10 to 12 per cent protein. Gluten is one of the proteins in wheat flour.

When you add flour to water or other water liquids, such as milk, the starch granules absorb about a third of their own weight in liquid.

When you heat starch, however, it goes a little crazy and its long molecule chains unravel and intermingle with each other and trap water. This thickens the liquid.

You can use cornflour instead. Look for the crossed grain logo to indicate it has been made with corn and not wheat. Use about half as much cornflour as wheat flour (follow the directions on the pack) and make a slurry with the cornflour and a little water before adding to melted butter to make a roux.

You can also use arrowroot flour, tapioca starch and potato starch. Follow the directions on the pack because the molecular make-up of the starches in these flours is different from that in wheat flour.

What is fat hen and what do I do with it? B. Northbridge

If you altered the famous Monty Python's Life of Brian "What have the Romans ever done for us?" speech to "What have the Arabs ever done for us?", you would have a fair understanding how they changed food in Europe.

They brought sugar, many spices, pomegranates, distillation of oils, dates, rice, hard wheat, oranges, lemons and spinach. Before spinach, the Europeans were fond of an annual soft-leafed plant variously known as orach, good King Henry, lamb's quarters or fat hen, depending on where you lived.

Its botanic name is Chenopodium album and it is a close relative of quinoa. Some traditional societies still grow it for its nutritious seeds. It is a common garden weed and can be used just as one would spinach.

In some parts of Lombardy it is used to make torta alla lombarda, a type of omelette with hard cheese and butter. Look for young leaves as the older leaves, like spinach, are high in oxalic acid.

Why do people get so funny about napkins when dining out? K. Loath

Napkins are culinary shibboleths. For those who know what to do with them, when and how to use them sets them apart from the others who don't.

If, for example, you tucked your napkin into your shirt, it would be seen as a great faux pas. In some circles it is almost as bad as stepping on one of the Queen's corgis.Instead, it should be placed over one's lap.

Using it like a face washer across a greasy face is considered uncouth by many. Instead, gently dabbing at the corners of one's lips is the way to go and when one leaves the table, one is expected to leave it unfolded on the table beside the plate.

Calling a napkin a ''serviette'' separates the chaff from the wheat for some, and may mean one doesn't get invited to the hunt next season.

- Good Food