USE A serrated knife when cutting something with a hard or crusty outside and a soft, fragile interior. Breads, tomatoes and citrus fruits all have outside surfaces resistant to straight edged knives. Their delicate inside textures will often be hacked or crushed by a straight edged blade before it can pierce through the skin. Serrated blades will quickly slice through the external skin without putting pressure on the delicate interior.

A serrated edge is formed on a standard blade by first cutting out a wave-like pattern, then sharply thinning out the metal on one or both sides of the wave-like cut by hollow grinding.

Many of the serrated knives available in the United States are marketed as bread knives. Rowoco produces a bread knife with a serrated edge of stainless steel. It has a black, mat finished wooden handle that holds the blade within, utilizing nickel-silver rivets. This is not a heavy weight, full tang, smooth bolstered piece of cutlery with the kind of serious craftsmanship that you find in Henckels, Wusthof, Case, Tommer and some Sabatier knives. It is a simple piece of work, but it does an excellent job and it is a good value at about $8 as opposed to a $15 to $50 a piece range.

For years it was my practice to discourage the purchase of these more expensive knives because there was no satisfactory method for sharpening them. It I was going to buy a piece of cutlery with a short working life, I wanted to do so at the lowest possible price. Now, however, with the introduction of various ceramic sharpening sticks and the crosscut sharpeners, it is possible to put a good edge back on a serrated blade and the acquisition of these finer knives makes good sense, especially if you have already begun to build a wardrobe of knives within one of these specific lines.

The same basic knife that I have been describing as a bread knife is also produced in a smaller version and marketed as a tomato, fruit or vegetable knife. When it comes to making neat slices of ripe tomaot or lemon without forcing out the juices, these blades are perfect.

The most dependable in quality for the least amount of money, is, once again, marketed under the Rowoco brand. Made of somewhat flexible, serrated stainless steel, this 4 1/2" blade has a slight point that can help puncture the heavy-textured outside layers of many fruits and vegtables. This knife makes it easier to peel small citrus fruits than to use a peeler. It will cut through rolls, sausages or skinny loaves of French or Italian bread. It is relatively inexpensive, generally retailing for about $4.30. It's a very good vaule. Both the bread knife and tomato knife are available in left hand models.

Serrated edges are also produced on frozen-food knives. These knives usually have two cutting edges. On one side are two different sizes of large, heavy teeth. These are used to rip through solid blocks of frozen food with a saw-like motion. If you freeze your own vegetables or fruits, purchase frozen foods in large blocks or wish to use only a portion of a standard-sized pack of frozen food these blades are an enormous help. I bake my bread in large batches and use my frozen food knife most often to cut a part of one.

When selecting a frozen-food knife, it is essential to choose one with a strong blade that will not bend or snap. Check to see that the blade is held to the handle with a rivet system. A great deal of paull is exerted on the blade when it is drawn back against the surface of the frozen food, so a poorly attached blade will be easily separated from the handle.

There is a widely available Rowoco model being imported from France. It has a strong, heat-resistant black plastic handle, and a polished stainless steel blade. It is a useful knife that has a second smooth serrted edge on its blade for breads, fruits and vegetables. It is 13" long overall with an 8 1/2" blade and reatils for about $9.50.