单项选择题

Passage 1

Nowadays, with plentiful ice and electric churning, few people recall the shared excitement of the era when making ice cream was a rarely scheduled event. Then the iceman brought to the back door, on special order, a handsome 2-foot-square cube of cold crystal and everyone in the family took a turn at the crank. The critical question among us children was, of course, who might lick the dasher. A century or so ago the novelist Stendhal knew only hand-churned ice cream and, when be first tasted it, ex-claimed, "What a pity this isn’t a sin!" Hand-churning is still tops for perfectionists for no power-driven machine has yet been invented that can achieve a comparable texture. Even French Pot, the very best commercial method for making ice cream, calls for finishing by hand. Ice creams are based on carefully cooked well-chilled syrups and heavy custards, added to unwhipped cream. No form of vanilla flavoring can surpass that of vanilla suger or of the bean itself, steeped in a hot syrup. If sweetened frozen fruits are incorporated into the cream mixture instead of fresh fruits, be sure to adjust sugar content accordingly. Make up mixtures for chum-frozen ice creams the day before you freeze, to increasingly fill the container only 3/4 full to permit expansion. To pack the freezer, allow 3 to 6 quarts of chipped or cracked ice to I cup of coarse rock sail. Pack about 1/3 of the freezer with ice and add layers of salt and ice around the container until the freezer is full. Allow the pack to stand about 3 minutes before you start turning. Turn slowly at first, about 40 revolutions a minute, until a slight pull is felt. Them triple speed for 5 to 6 minutes. If any additions, such as finely cut candied or fresh fruits or nuts are to be made, do so at this point. Then repack and taper off the churning to a- bout 80 revolutions a minute for a few minutes more. The cream should be ready in 10 to 20 minutes, depending on the quality. If the ice cream or ice is to be used at once, it should be frozen harder then if you plan to serve it later. Should the interval be 2 hours or more, packing will firm it. To pack, pour off the salt water in the freezer and wipe off the lid. Remove the dasher carefully, making sure that no salt or water gets into the cream container Scrape the cream down from the sides of the container. Place a cork in the lid and replace the lid. Repack the container in the freezer with additional ice and salt, using the same proporions as before. Cover the freezer with newspapers, a piece of carpet or other heavy material. The cream should be smooth when served, If it proves granular, you used too much salt in the packing mixture, overfilled the inner, container with the ice cream mixture or turned too rapidly. If you are making a large quantity with the idea of storing some in the deep-freeze, package in sizes you plan on serving: Should ice cream be allowed to melt even slightly and is then refrozen, it loses in volume and even more in good texture.

When ice cream is being hand-churned it is surrounded by a mixture of ______.