United States Patent Office
3 067 01S
SPOILAGE INDICATOR FOB. FOOD CONTAINERS Ray F. Lawdermilt, 22S Lincota Ave., North Vernon, Ind. Filed Jan. 29, 1960, Ser. No. 5,473 14 Claims. (CI. 23—253)
This invention relates to spoilage indicators for food containers, and more particularly to spoilage indicators for milk cartons, although, with suitable modifications, the indicator may be applied to various types of food containers.
In the dairy industry there has been considerable controversy as to what sanitary significance can be attached to the presence of large numbers of bacteria in milk. Many of the species which multiply most rapidly in milk are entirely harmless, and, in fact, certain fermented milks which contain enormous numbers of lactic acid bacteria are believed by many to be particularly wholesome, such as buttermilk, sour cream and the like. On the other hand, it has been established by research that only as a result of insanitary methods or insufficient safeguards in the handling of milk can the large numbers of bacteria sometimes found in market milk be accounted for. It has become the accepted practice that, in general, the presence of large numbers of bacteria reflects serious doubt upon the sanitary quality and wholesomeness of milk. The National Commission on Milk Standards, for example, specify that for raw milk the bacteria count shall not exceed 10,000 per cubic centimeter at the time of delivery to the consumer. For pasteurized milk, the count shall not exceed 200,000 per cubic centimeter in the raw stage, which is reduced to 10,000 per cubic centimeter at the time of delivery, to the customer.
The following resolutions have been adopted by the National, Commission on Milk Standards:
"Whereas, milk is one of the most perishable foods, being extremely susceptible to contamination and decomposition; whereas the milk consumer is justified in demanding that milk should be clean, fresh, and cold, in addition to having the element of safety; whereas milk which is from healthy cows and is clean, fresh, and which has been kept cold will always have a low bacterial count; whereas milk that is dirty, stale, or has been left warm, will have a high bacterial count, therefore it is resolved:
"First: That the health officer is justified in using the bacterial count as an indicator of the degree of care exercised by the producer and dealer in securing milk from healthy cows and in keeping the same clean, fresh, and cold.
"Second: That the health officer is justified in condemning milk with a high bacterial count as being either unhealthy or decomposed, or containing dirt, filth, or decomposed material as a result of the multiplication of bacteria due to age and temperature.
"Third: That the health officer is justified in ruling that large numbers of bacteria are a source of possible danger, and that milk containing large numbers of bacteria is to be classed as unwholesome, unless it can be shown that the bacteria present are of a harmless type, as for example, the lactic acid bacteria in buttermilk, or other especially soured milks."
In the dairy industry, various local controlling authorities have imposed rather stringent controls on dairy farmers and collecting and processing plants, and regular tests, including bacterial counts, are run on the milk at various stages in the bulk processing. These are on such a scale that large and complex equipment is customary and practical. However, under present conditions of distribution, when the milk has been bottled, tests are no longer made. If the milk is stored for an unduly long period
of time or has not been kept at a constant low degree of temperature, spoilage or bacteria multiplication may occur, and the consumer has unsafe or spoiled milk on his hands. The retailer has no way of assuring himself that
5 he is sending safe, fresh milk to his customers. From the standpoint of the public authorities, this is an area over which there is no adequate control.
In milk in which an undue amount of bacterial multiplication has occurred, and wherein the milk has passed
Iq below the minimum quality for human consumption, it has been found that one of the products generated is carbon dioxide. Carbon dioxide, upon contact with moisture, forms the hypothetical acid, carbonic acid. The acid is unstable but will react with potassium hydroxide, or
15 similar bases, and this is measurable. Therefore, milk in a container, which has spoiled, has above the liquid body a substantial excess of carbon dioxide. Tests indicate that milk at the point of spoilage, which has ceased to be fit for human consumption, has a pH of 5.9. In
2o its fresh state, milk has a pH of 6.5 to 6.6.
There is urgent need, therefore, for an indicator for spoilage of milk which will inform the consumer, retailer or the public authorities, without complex tests, the condition of a container of milk. This indicator must be
25 low in cost and practical to apply. Further, the indicator itself must not contaminate the product in any way, and there must be no harmful effect on taste, color or container sealing.
It is an object of the invention to provide a spoilage
30 indicator which may be placed on each milk or food container, and which will indicate at a glance whether the product in the container is fit for human consumption.
Another object of the invention is to provide an indicator for food containers wherein a simple color change
35 will signal that milk or food in the container is no.longer fresh, and is probably spoiled.
A further object of the, invention is to provide an indicator which is cheap and economical to make, which may be manufactured and distributed as a finished cap
40 sule, and which may be applied to milk or food containers in a simple operation either by hand or by machine.
Still another object of the invention is to provide a chemical spoilage indicator which will meet all sanitary standards of the public health authorities, which will not
45 affect the milk or food as to taste, color and purity, and in which the indicator material is not in direct contact with the milk or food product.
With the above and other objects in , view, as will. Be presently apparent, the invention consists in general of
50 certain novel details of construction and combinations of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly claimed.
In the accompanying drawings, like characters' of reference indicate like parts in the several views, and
55 FIGURE 1 is a fragmentary side elevation, partly broken away, showing the spoilage indicator of the invention mounted in the upper top panel of a milk carton;
FIGURE 2 is a fragmentary cross-sectional view of the 60 spoilage indicator as mounted in a cap or top of a standard milk bottle;
FIGURE 3 is a fragmentary view, partly broken away, of a modification of the spoilage indicator, as applied to metallic food containers; 65 FIGURE 4 is an isometric view of the plastic hat which forms one element of the first form of the invention;
FIGURE 5 is an isometric view of the absorbent indicator disc of the first form of the invention;