possible that the heating will kill all of the bacteria but the
spores will be left alive. By the following day, however,
the majority of these spores will have again changed them-
selves into the ordinary forms of bacteria, and a second
heating will kill these forms. A third heating is safest to
make sure that any spores remaining the second day are
destroyed. Both yeasts and bacteria are too small to be
seen without a microscope ; but of the two, yeasts are much
the larger. While a yeast cell is about one three-thou-
sandth of an inch in diameter, even the largest bacterium
has a diameter of not more than one ten-thousandth of
an inch. It might well seem as if organisms as small as
this could not do us either much harm or much good, and
this would probably be true if it were not for the wonderful
rate at which they can multiply. In a bacterium, division
may take place every half hour, and at that rate, in only
one day, conditions being favorable, a single cell could
produce about seventeen million others. If, then, food is
to be kept from spoiling, it is obviously necessary to
exclude the entrance of even one bacterium.
When bacteria first act upon food, the result may be
only beneficial; the good flavor of butter and some
cheeses is undoubtedly due to their action. Bacteria,
however, will finally render food unfit for use, producing
decay and putrefaction. But what a world it would be
if micro-organisms did not bring about these processes.
Our world would be littered with useless material, and the
soil long ago would have become exhausted.
Bacteria may be divided into three distinct classes :
first, those capable of producing diseases, such as typhoid
and diphtheria; second, those which in the process of
growth produce substances poisonous to us. These sub-
stances, called ptomains, are the cause of the ptomain poi-
soning cases which occur from time to time. The third
24 FOOD STUDY
class is composed of those that are either harmless or
beneficial to us. The bacteria which cause milk to sour not
only are not any more poisonous to us than are any of the
other vegetable plants used for food, but they may be of
positive benefit in keeping down the growth of more harm-
ful organisms.
"Swat the fly" has become a slogan in modern times.
A glance at the enlarged diagram of a fly, particularly of
the feet, will show why it is considered objectionable to
have flies around, and especially so to have them crawl
over food. Coming from infected material and filth, they
may bring with them all kinds of germs. If the germs are
introduced into food material, where every condition is
right for their reproduction, it is evident how trouble
may occur. It is very necessary then, that flies be ex-
cluded from houses as far as possible. Any flies that find
entrance must be killed or caught, and care must be taken
not to allow heaps of manure or garbage, or other fly-
breeding material, to stand long enough for their larvas to
develop and escape. Much the easiest method of keeping
free from flies is to control possible breeding places. A
new kind of garbage can acts as fly-catcher and, placed
just outside the house, may catch many flies which would
otherwise find their way in. Then garbage and flies
together must be disposed of. Other insects may, of
course, also act as carriers of germs, but the fly especially
brings them.
REFERENCE
Food study
1917Page 16
Presented as published in 1917. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
AI-modernized reading of the original text
possible that the heating will kill all of the bacteria but the spores will be left alive. By the following day, however, the majority of these spores will have again changed themselves into the ordinary forms of bacteria, and a second heating will kill these forms. A third heating is safest to make sure that any spores remaining the second day are destroyed. Both yeasts and bacteria are too small to be seen without a microscope ; but of the two, yeasts are much the larger. While a yeast cell is about one three-thousandth of an inch in diameter, even the largest bacterium has a diameter of not more than one ten-thousandth of an inch. It might well seem as if organisms as small as this could not do us either much harm or much good, and this would probably be true if it were not for the wonderful rate at which they can multiply. In a bacterium, division may take place every half hour, and at that rate, in only one day, conditions being favorable, a single cell could produce about seventeen million others. If, then, food is to be kept from spoiling, it is obviously necessary to exclude the entrance of even one bacterium.
When bacteria first act upon food, the result may be only beneficial; the good flavor of butter and some cheeses is undoubtedly due to their action. Bacteria, however, will finally render food unfit for use, producing decay and putrefaction. But what a world it would be if micro-organisms did not bring about these processes. Our world would be littered with useless material, and the soil long ago would have become exhausted.
Bacteria may be divided into three distinct classes : first, those capable of producing diseases, such as typhoid and diphtheria; second, those which in the process of growth produce substances poisonous to us. These substances, called ptomains, are the cause of the ptomain poisoning cases which occur from time to time. The third
class is composed of those that are either harmless or beneficial to us. The bacteria which cause milk to sour not only are not any more poisonous to us than are any of the other vegetable plants used for food, but they may be of positive benefit in keeping down the growth of more harmful organisms.
"Swat the fly" has become a slogan in modern times. A glance at the enlarged diagram of a fly, particularly of the feet, will show why it is considered objectionable to have flies around, and especially so to have them crawl over food. Coming from infected material and filth, they may bring with them all kinds of germs. If the germs are introduced into food material, where every condition is right for their reproduction, it is evident how trouble may occur. It is very necessary then, that flies be excluded from houses as far as possible. Any flies that find entrance must be killed or caught, and care must be taken not to allow heaps of manure or garbage, or other flybreeding material, to stand long enough for their larvas to develop and escape. Much the easiest method of keeping free from flies is to control possible breeding places. A new kind of garbage can acts as fly-catcher and, placed just outside the house, may catch many flies which would otherwise find their way in. Then garbage and flies together must be disposed of. Other insects may, of course, also act as carriers of germs, but the fly especially brings them.