43. — Effect of temperature. Prepare 3 tubes with molasses and water as above described and inoculate each with 3 drops of yeast in water. Place one tube in a refrigerator, a second in a moderately warm temperature, above 70° F., and a third in a warmer place, near a stove or radiator (temp, about 90° F.). Compare the three at the end of three, six, and twenty-four hours, and note the effect of temperature upon growth. 44. - - Effect of light. Prepare two tubes in the same way and set one in a bright light and the other in a dark place. Keep both tubes 32 LABORATORY MANUAL OF FOODS AND COOKERY at the same temperature and determine whether light has any effect upon the rapidity of growth. 45. - - Make a small cavity in the surface of a glass of jelly. Place a drop of fermented grape juice in the cavity, replace the paraffin and tin covers, and allow the jelly to remain in a dark cup- board. Examine after three days and notice the changes which have occurred in : 1 . taste 2. odor 3. consistency 46. - - a. Allow jelly to remain uncovered for a few minutes after it has cooled. Place the tin cover on jelly glass and set aside in warm, dark place. b. Examine daily for growths which will soon appear. c. Try to determine what kinds of mold appear.1 d. What is the coral pink mass which will probably appear? e. Allow the action of microorganisms to continue until the jelly becomes semi-liquid. Place it in a bottle and cork tightly. /. Keep the bottle in a warm place and notice the changes taking place. g. What are the bubbles and froth which appear when the cork is removed ? h. What microorganisms other than molds have been at work? 47. - - a. Partly fill a sterile jar a with hot peaches and sirup just ready for canning. Repeat in a second jar b. b. Adjust the rubber band and seal a to keep out the air. Omit the rubber band on &, but clamp down the cover. c. Place a and b together with a jar filled and sealed and containing no air bubbles in a warm, dark place. Compare daily for signs of the action of microorganisms. 1 An idea of the probable kind may be obtained by noting color and general appearance and comparing with what has already been learned. For actual iden- tification the "key" at the back of Buchanan's Household Bacteriology will be found most useful. CANNING AND PRESERVING 33 d. Compare a and b. Why should a show molds when the outside air is excluded? e. Why does no change occur in the third jar? 48. - - From these experiments what conclusions do you make as to: a. The covering of jelly or jams with hot paraffin or paper wet in alcohol. b. The exclusion of air or air bubbles from a canned mixture. c. The rate of action of microorganisms in a solution as jam or jelly compared with that in a sirup as canned peaches. d. In what way can sugar in large amounts act as a partial preservative of fruits ? Definitions As usage differs somewhat the following definitions are given to show the sense in which each of the terms is used in this book. Canned food - - food products preserved in air-tight containers with or without heat and addition of sugar or acid. Preserves - - whole fruit or large pieces of fruit in a heavy solution of sugar. Jams - - fruit which is finely divided or reduced to a pulp in a heavy solution of sugar.

AI-modernized reading of the original text

43. — Effect of temperature. Prepare 3 tubes with molasses and water as above described and inoculate each with 3 drops of yeast in water. Place one tube in a refrigerator, a second in a moderately warm temperature, above 70° F., and a third in a warmer place, near a stove or radiator (temp, about 90° F.). Compare the three at the end of three, six, and twenty-four hours, and note the effect of temperature upon growth. 44. - - Effect of light. Prepare two tubes in the same way and set one in a bright light and the other in a dark place. Keep both tubes at the same temperature and determine whether light has any effect upon the rapidity of growth. 45. - - Make a small cavity in the surface of a glass of jelly. Place a drop of fermented grape juice in the cavity, replace the paraffin and tin covers, and allow the jelly to remain in a dark cupboard. Examine after three days and notice the changes which have occurred in : 1 . taste 2. odor 3. consistency 46. - - a. Allow jelly to remain uncovered for a few minutes after it has cooled. Place the tin cover on jelly glass and set aside in warm, dark place. b. Examine daily for growths which will soon appear. c. Try to determine what kinds of mold appear.1 d. What is the coral pink mass which will probably appear? e. Allow the action of microorganisms to continue until the jelly becomes semi-liquid. Place it in a bottle and cork tightly. /. Keep the bottle in a warm place and notice the changes taking place. g. What are the bubbles and froth which appear when the cork is removed ? h. What microorganisms other than molds have been at work? 47. - - a. Partly fill a sterile jar a with hot peaches and sirup just ready for canning. Repeat in a second jar b. b. Adjust the rubber band and seal a to keep out the air. Omit the rubber band on &, but clamp down the cover. c. Place a and b together with a jar filled and sealed and containing no air bubbles in a warm, dark place. Compare daily for signs of the action of microorganisms. 1 An idea of the probable kind may be obtained by noting color and general appearance and comparing with what has already been learned. For actual identification the "key" at the back of Buchanan's Household Bacteriology will be found most useful. d. Compare a and b. Why should a show molds when the outside air is excluded? e. Why does no change occur in the third jar? 48. - - From these experiments what conclusions do you make as to: a. The covering of jelly or jams with hot paraffin or paper wet in alcohol. b. The exclusion of air or air bubbles from a canned mixture. c. The rate of action of microorganisms in a solution as jam or jelly compared with that in a sirup as canned peaches. d. In what way can sugar in large amounts act as a partial preservative of fruits ? Definitions As usage differs somewhat the following definitions are given to show the sense in which each of the terms is used in this book. Canned food - - food products preserved in air-tight containers with or without heat and addition of sugar or acid. Preserves - - whole fruit or large pieces of fruit in a heavy solution of sugar. Jams - - fruit which is finely divided or reduced to a pulp in a heavy solution of sugar.

A laboratory manual of foods and cookery