A. Class Experiment. One Cause of Fruit Spoiling. Take a piece of bread, moisten it with water, and leave it exposed upon a plate during the lesson. Then cover with a saucer; leave for two days. If possible, examine under a miscroscope.
B. To Can a Jar of Peaches.
In canning fruit, use a fourth to a third of the weight of the fruit in sugar and from two and a half to three cups of water for each pound of sugar. Make a syrup by boiling the sugar and water together for three to five minutes. Scald the peaches by dipping in boiling water long enough to loosen the skin; peel, cut in halves, and remove the stones. Then, cook the fruit in the syrup. Often, only part of the fruit is cooked at a time, so that there need not be an excess of the syrup. While the peaches are cooking, sterilize a jar and cover, as the test tubes were sterilized in the last lesson. When the peaches are done, place the jar either in hot water or on a cloth wrung out of hot water. Fill the jar with fruit and pour in syrup until it overflows. If there is not enough syrup, add boiling water. As quickly as possible, put on a rubber and screw on the cover. When the jar is cold, screw the cover as tight as possible, being sure that it is air tight.
C. Another Method of Canning.
Fill a jar with peaches, cut in half and stoned, within one inch of the top. Make a syrup and pour over the fruit. Adjust the rubber, screw cover on lightly or adjust top without clamping, and place the jar in a moderate oven or in a steamer. Cook till the fruit appears clear and waxy. Then remove from the oven and tighten the cover.
Compare the advantages and disadvantages of these two methods of canning.
Molds are so well known to everyone that it is surprising to learn that there is no such botanical classification. All plants that do not contain chlorophyll, the coloring matter which makes an ordinary plant green, are called colorless plants or fungi. The fungi include mushrooms and toadstools, but of more interest to the housekeeper are molds, yeasts, and bacteria. All these are plants which feed on organic food and so may be found living on any of our foods that are not properly taken care of.
While nearly everyone recognizes molds at sight, few have looked at them closely enough to realize what really beautiful plants they are. When they begin growing, they appear at first as soft, fluffy masses which are made up of a tangle of much-branched threads. Each thread, called a mycelium, looks white as it is seen ordinarily,, but appears nearly colorless under a microscope. When the mold is older, perhaps after two days, it may show a color, blue, green, brown, black, red, or pink, each color marking a different variety of mold. The color is due to the so-called spores, which are reproductive bodies and which, if they contained nutritive material, would be seeds.
Each different species of mold has a different way of forming spores.
Perhaps the most common household mold, one that is almost always found on moldy bread, is penicillium. This is a blue mold; that is, at the time of spore formation, it becomes blue, or bluish-green. This color is due to the color of the spores themselves. When the mold is a day or two old, the mycelium sends up vertical threads which soon divide into many little branches. Then, each branch begins to divide by ring-like constrictions as if it were trying to make beads of itself, until, finally, the branch is nothing more than a string of little round balls, each of which is a spore. These spores are so light that a breath of wind blows them away, and they float off in the air in search of new food material.
Mucor, another mold commonly found on bread, is coarser than penicillium, so that the threads are seen more easily. When it is ready to form spores, the vertical threads, instead of branching, form on their ends small round knobs or sacs, and inside these balls are formed thousands of spores, which, when the sac bursts, are sown broadcast. These knobs on the mold look like small black specks. Another mold, aspergillus, instead of forming the spores inside the sac, forms them as beads on the outside.
From Conn's "Bacteria, Yeasts, and Molds In the Home." Penicillium, Common Mold, as seen under the microscope.
During the process of growth, all these molds may send their branching threads deep down into the food on which they are growing so that more than the surface may be affected. As a result of their growth, they soon change not only the appearance of the food, but the flavor and odor as well. If the mold is allowed to go on growing, the food may be entirely spoiled. On the other hand, some molds produce delicious flavors, and many of the distinctive flavors of our different cheeses are produced in this way. Fruits are particularly subject to decay as a result of mold action. If the skin of fruit is broken, the molds have an especially good chance to get at the food material inside and begin the process of decay.
Spores of PEnicillium Sprouting.
From Conn's " Bacteria, Yeasts, and Molds in the Home." Growth from Two Spores, Two Days Later.
A temperature as hot as boiling, or even a little lower, will soon kill a plant, and molds are no exception to this rule. When fruit is canned, then, it is boiled not so much to cook the fruit, as to be sure that it contains no live spores; and then it must be put away air tight so that no new spores can blow in.
From Conn's "Bacteria, Yeasts, and Molds In the Home." MUCOR, ANOTHER MOLD FOUND ON BREAD.
From Conn's "Bacteria, Yeasts, and Molds in the Home." Aspergillus, showing Mycelium and Spore Clusters
This is one of the things accomplished in canning, although the plants to be guarded against may be bacteria and yeasts as well as molds.
Conn. "Bacteria, Yeasts, and Molds in the Home." Section I,
Molds. Cornell Reading Course for the Farm Home. "The Preservation of
Food in the Home," Part I. U. S. Farmers' Bulletin No. 426. "Canning Peaches on the Farm." U. S. Farmers' Bulletin No. 359. "Canning Vegetables in the
Home." U. S. Farmers' Bulletin No. 203. "Canned Fruits, Preserves, and
Jellies." Ohio State University Extension Bulletin, Vol. VI, Supplement 2,
No. 2. "The Canning of Fruits and Vegetables."
1. After sterilizing, why must the fruit be kept covered and air tight?
2. After a jar is sterilized why should it not be wiped out with the dish cloth? Why must care be taken not to touch the inside of the jar with the fingers?
3. Why is the rubber dipped in boiling water, and why is it not boiled with the jar and cover?
4. How can the jar be tested before using? If leakage is due to a poorly made jar and not to a poor rubber, what uses may be made of the jar?
5. Describe the different methods of canning.
6. How can a jar that sticks be opened?
7. What different styles of cans are commonly used? Discuss the advantages of each kind.