36. - - Molds in cheese. Obtain a bit of Roquefort cheese. Cut it open and remove a bit of the green mass in the middle by means of a knife point or platinum wire. Sow this substance upon the surface of a dish of hardened gelatin and set aside for growth. After two or three days, the molds will begin to develop and may be studied with a microscope. When they begin to produce spores, they should, if possible, be studied sufficiently to determine the species. 30 LABORATORY MANUAL OF FOODS AND COOKERY EXPERIMENTS ILLUSTRATING THE ACTION OF BACTERIA 37. - - Putrefaction. Place in a series of test tubes a, b, c, d, e, f, g, h, with a little cold water, the following : a - - a small piece of chopped raw meat b - - a small amount of white of egg c - - \ tsp. bread flour d- -\ tsp. cornstarch e — | tsp. cane sugar / - - a small amount of ground dried peas g - - \ tsp. melted butter h - - \ tsp. olive oil. Cover each test tube with a piece of cheesecloth or stop with cotton. Place all the test tubes together in a warm place for three days and watch to determine which will putrefy and in what order. Putrefaction can be detected by the disagreeable odor and slimy condition of the water. 38. - - Effect of moisture. Place a small amount of the following foods in dry test tubes a, b, c, d, e, f. In a duplicate series place the same foods, but moisten each with water. Allow all to remain in a warm place and compare at the end of 3 days. Notice the effect of the water in evidently promoting putrefaction. Foods - - dry and wet. a - - dried crushed peas. b - - oatmeal c — bread d - - entire wheat flour e - - bread flour / - - graham cracker 39. - - Effect of temperature. Place bits of meat with a little water in three test tubes. Put the first tube in an ice chest, the second in CANNING AND PRESERVING 31 ordinary room temperature, and the third close to a stove or radiator where the temperature is high. Notice the rapidity of putrefaction in each case. 40. - - Effect of boiling. Chop finely some raw beef and place it in water, warming slightly, but not heating it to more than 130° F. Divide into two parts, place each in a test tube, setting one aside without further treatment, but bringing the other to a brisk boil for a moment and then setting beside the first. At the end of twenty- four hours, examine to determine if putrefaction has occurred. Effect of freezing. A visit to a cold storage plant with subse- quent discussions will be more beneficial than an experiment to show the effect of freezing upon bacteria. EXPERIMENTS ILLUSTRATING YEASTS AS RELATED TO FRUITS AND SIRUPS 41. - - Fermentation of cider. Grind up a few apples and strain the juice from the same by squeezing through cheesecloth. Collect the juice in test tubes and allow it to stand for a few days. A fer- mentation soon appears and the juice turns to cider. Examine the sediment with a microscope and detect the presence of yeast. Close up the tube with a cotton plug and leave it for a number of weeks, determining whether it subsequently becomes acid by the develop- ment of acetic acid. 42. — Fermentation of grape juice. Proceed as above, using grapes instead of apples. The juice will become wine if fermenta- tion occurs properly.

AI-modernized reading of the original text

36. - - Molds in cheese. Obtain a bit of Roquefort cheese. Cut it open and remove a bit of the green mass in the middle by means of a knife point or platinum wire. Sow this substance upon the surface of a dish of hardened gelatin and set aside for growth. After two or three days, the molds will begin to develop and may be studied with a microscope. When they begin to produce spores, they should, if possible, be studied sufficiently to determine the species. EXPERIMENTS ILLUSTRATING THE ACTION OF BACTERIA 37. - - Putrefaction. Place in a series of test tubes a, b, c, d, e, f, g, h, with a little cold water, the following : a - - a small piece of chopped raw meat b - - a small amount of white of egg c - - \ tsp. bread flour d- -\ tsp. cornstarch e — | tsp. cane sugar / - - a small amount of ground dried peas g - - \ tsp. melted butter h - - \ tsp. olive oil. Cover each test tube with a piece of cheesecloth or stop with cotton. Place all the test tubes together in a warm place for three days and watch to determine which will putrefy and in what order. Putrefaction can be detected by the disagreeable odor and slimy condition of the water. 38. - - Effect of moisture. Place a small amount of the following foods in dry test tubes a, b, c, d, e, f. In a duplicate series place the same foods, but moisten each with water. Allow all to remain in a warm place and compare at the end of 3 days. Notice the effect of the water in evidently promoting putrefaction. Foods - - dry and wet. a - - dried crushed peas. b - - oatmeal c — bread d - - entire wheat flour e - - bread flour / - - graham cracker 39. - - Effect of temperature. Place bits of meat with a little water in three test tubes. Put the first tube in an ice chest, the second in ordinary room temperature, and the third close to a stove or radiator where the temperature is high. Notice the rapidity of putrefaction in each case. 40. - - Effect of boiling. Chop finely some raw beef and place it in water, warming slightly, but not heating it to more than 130° F. Divide into two parts, place each in a test tube, setting one aside without further treatment, but bringing the other to a brisk boil for a moment and then setting beside the first. At the end of twentyfour hours, examine to determine if putrefaction has occurred. Effect of freezing. A visit to a cold storage plant with subsequent discussions will be more beneficial than an experiment to show the effect of freezing upon bacteria. EXPERIMENTS ILLUSTRATING YEASTS AS RELATED TO FRUITS AND SIRUPS 41. - - Fermentation of cider. Grind up a few apples and strain the juice from the same by squeezing through cheesecloth. Collect the juice in test tubes and allow it to stand for a few days. A fermentation soon appears and the juice turns to cider. Examine the sediment with a microscope and detect the presence of yeast. Close up the tube with a cotton plug and leave it for a number of weeks, determining whether it subsequently becomes acid by the development of acetic acid. 42. — Fermentation of grape juice. Proceed as above, using grapes instead of apples. The juice will become wine if fermentation occurs properly.

A laboratory manual of foods and cookery