Vegetables suitable for pickling are : cauliflower beets cabbage onions Fruits suitable for spicing are : blackberries pears peaches red tomatoes Fruits suitable for salting are : cucumbers, large and small Fruits suitable for drying are : currants apricots grapes plums peaches prunes pears cranberries apples - - sweet, sour Fruits suitable for beverages are : grapes apples - - sweet, sour currants cherries raspberries lemons elderberries oranges CANNING AND PRESERVING 25 Preservation of fruits is secured by : 1. Heat and exclusion of air Ex. - - canned peaches 2. Exclusion of air but heat not necessary because the mate- rial itself is strongly acid. Ex. - - canned tomato, canned rhubarb 3. Strong acids. Ex. - - pickled pears 4. Strong brine Ex. - - salted cucumbers 5. Heavy solution of sugar. Ex. - - preserves, jams, conserves, butters, honey, jellies. Relation to Microorganisms All the above methods of preserving fruits and vegetables depend upon either destroying, or preventing the action of microorganisms which would cause the food to ferment, decay, or become moldy. The microorganisms which thus spoil or injure food are cer- tain species of the three groups : a. Molds. b. Yeasts. c. Bacteria. Molds are seen often as yellow, green, or white growths, very beautiful in color and arrangement, upon lemons, oranges, bread, jams, jellies, and sirups. Some typical forms often found on food are : bread mold - - Mucor stolonifer green cheese mold, or blue mold - - Penicillium glaucum 26 LABORATORY MANUAL OF FOODS AND COOKERY mold of decaying vegetation : blue green - - Aspergillus f umigatus yellow - - Aspergillus flavescens black - - Aspergillus niger. Yeasts cannot usually be seen without the microscope, but evidence of their work is shown by fermentation of fruit juices accompanied by bubbles of gas or a loud pop when a cork or cover is removed. Bacteria are all too small to be seen without a good micro- scope. The work of bacteria is shown generally by a disa- greeable sour taste often accompanied by an unpleasant odor with or without an evolution of gas. The following experiments will illustrate the work of molds, yeasts, and bacteria, but the detailed study of these organisms and the changes which they bring about in food materials is a science in itself and one of the greatest interest and importance to all students of foods and cookery. The reading and study of Buchanan's Household Bacteriology (which treats of the yeasts and molds as well as the bacteria of economic impor- tance) is especially recommended. EXPERIMENTS 24. - - Collection of mold for study. a. Expose a piece of moist bread to the air of the room for about 10 minutes. Keep in a moist chamber and watch for the development of mold. A jelly glass inverted over the bread on a plate will do for the glass chamber. b. Expose a dish containing a freshly opened baked potato to the air of the room for about 10 minutes. Cover; keep in locker and watch for the development of mold. c. Bring into the laboratory anything that you can find on which mold is growing. CANNING AND PRESERVING 27 25. — Description of mold. Describe briefly the general appearance of these various forms under a small magnifying glass (15 diam.) or under a dissecting microscope (15 diam.).

AI-modernized reading of the original text

Vegetables suitable for pickling are : cauliflower beets cabbage onions Fruits suitable for spicing are : blackberries pears peaches red tomatoes Fruits suitable for salting are : cucumbers, large and small Fruits suitable for drying are : currants apricots grapes plums peaches prunes pears cranberries apples - - sweet, sour Fruits suitable for beverages are : grapes apples - - sweet, sour currants cherries raspberries lemons elderberries oranges Preservation of fruits is secured by : 1. Heat and exclusion of air Ex. - - canned peaches 2. Exclusion of air but heat not necessary because the material itself is strongly acid. Ex. - - canned tomato, canned rhubarb 3. Strong acids. Ex. - - pickled pears 4. Strong brine Ex. - - salted cucumbers 5. Heavy solution of sugar. Ex. - - preserves, jams, conserves, butters, honey, jellies. Relation to Microorganisms All the above methods of preserving fruits and vegetables depend upon either destroying, or preventing the action of microorganisms which would cause the food to ferment, decay, or become moldy. The microorganisms which thus spoil or injure food are certain species of the three groups : a. Molds. b. Yeasts. c. Bacteria. Molds are seen often as yellow, green, or white growths, very beautiful in color and arrangement, upon lemons, oranges, bread, jams, jellies, and sirups. Some typical forms often found on food are : bread mold - - Mucor stolonifer green cheese mold, or blue mold - - Penicillium glaucum mold of decaying vegetation : blue green - - Aspergillus f umigatus yellow - - Aspergillus flavescens black - - Aspergillus niger. Yeasts cannot usually be seen without the microscope, but evidence of their work is shown by fermentation of fruit juices accompanied by bubbles of gas or a loud pop when a cork or cover is removed. Bacteria are all too small to be seen without a good microscope. The work of bacteria is shown generally by a disagreeable sour taste often accompanied by an unpleasant odor with or without an evolution of gas. The following experiments will illustrate the work of molds, yeasts, and bacteria, but the detailed study of these organisms and the changes which they bring about in food materials is a science in itself and one of the greatest interest and importance to all students of foods and cookery. The reading and study of Buchanan's Household Bacteriology (which treats of the yeasts and molds as well as the bacteria of economic importance) is especially recommended. 24. - - Collection of mold for study. a. Expose a piece of moist bread to the air of the room for about 10 minutes. Keep in a moist chamber and watch for the development of mold. A jelly glass inverted over the bread on a plate will do for the glass chamber. b. Expose a dish containing a freshly opened baked potato to the air of the room for about 10 minutes. Cover; keep in locker and watch for the development of mold. c. Bring into the laboratory anything that you can find on which mold is growing. 25. — Description of mold. Describe briefly the general appearance of these various forms under a small magnifying glass (15 diam.) or under a dissecting microscope (15 diam.).

A laboratory manual of foods and cookery