Invented by Dwight W. Miller, Jon G. Wilkes, Eric D. Conte, GOVERNMENT OF UNITED STATES HEALTH AND HUMAN SERVICES OFFICE OF TECHNOLOGY TRANSFER NATIONAL INSTITUTES OF HEALTH, Secretary of, Department of, US Department of Health and Human Services
The GOVERNMENT OF UNITED STATES HEALTH AND HUMAN SERVICES OFFICE OF TECHNOLOGY TRANSFER NATIONAL INSTITUTES OF HEALTH, Secretary of, Department of, US Department of Health and Human Services invention works as followsA food quality indicator device is an indicator compound placed on a substrate. The indicator compound’s color changes due to the presence volatile compounds such as volatile bases in spoiled foods, even if the food has been frozen. The indicator compound can also detect the presence of unwanted amine-producing biological agents, such as bacteria and fungi. The indicator compound is usually contained in a polymeric matrix that is placed on the substrate. Some examples of suitable indicator compounds are halogenated Azo dyes, sulfonated Triphenylmethane Dyes and sulfonated Hydroxy-functional Triphenylmethane Dyes.
Background for Food quality indicator device
The determination of whether food is spoiled is an important issue for many people, from the food producer to consumers, including regulators, importers and exporters to brokers. There are many food products that can spoil. These include grains, fruits and vegetables. One of the most serious areas of concern is spoilage in red meat, pork and poultry, as well as processed meat products and seafood. There are many dangers associated with spoiled foods, including illness from eating the food. These illnesses can be fatal, especially for the very young and very old, as well as those with compromised immune systems.
Many foods are packaged and/or frozen to prevent spoilage. It is difficult to check for spoilage in frozen and packaged foods which contain a lot of red meat, pork and poultry. Unwrapping packaged food is often necessary to inspect it and then repackage it if possible. To determine the quality of frozen food, current techniques often use color, smell and texture. The United States Food and Drug Administration still uses organoleptic analysis to test seafood. To determine the condition of seafood, this method involves thawing it and then performing an olfactory assessment by highly-trained experts.
There are devices that can be used to determine the quality of frozen foods, and they don’t require any thawing. These devices can be difficult to use and/or bulky so they aren’t readily accessible and/or easy to operate by untrained individuals such as consumers or grocers.
Another embodiment is an indicator compound that has a color transition in a pH range of about pH 1.0 to pH 6.0. An indicator compound can also be a halogenated or sulphonated dye, or a sulfurated hydroxy-functional triphenylmethane color dye. A polymeric matrix is a coating of polymer on the substrate that holds the indicator compound.
Another aspect is the method of making an indicator device. This involves forming a solution containing an indicator compound, solvent and an acid. The solution is then enriched with silane monomer material. The solution is placed on a substrate. The silane monomer material polymerizes to create a silica matrix, in which the indicator compound can be disposed.
Another aspect of the invention is a method to detect the presence of an unwelcome amine-producing biologic agent on a food product. The indicator device is exposed the food product. An indicator device is composed of a substrate and an indicator substance. The indicator compound reacts colorimetrically to volatile bases produced by the unwanted amine-producing biologic agent. Visual inspection of the device is done to check for the presence of the unwanted biological agent in the food product. This can be done by looking at the color change of the indicator compound.
The present invention’s summary is not meant to be exhaustive and cover every illustrated embodiment. These embodiments are best illustrated by the figures and detailed description that follow.
The present invention can be applied to many devices and methods that colorimetrically determine food quality. The invention’s scope is not limited. However, it will allow you to appreciate the various aspects of the invention through the discussion of the devices, methods, and products that are used in the detection and detection of food spoilage in red meat, pork and poultry products.
FIG. 1. An indicator layer 22 is placed on a substrate 24 in a food quality indicator device 20. Substrate 24 can be made of materials that support indicator layer 22 such as paper, plastic, (e.g. polyester, polyethylene or polyvinyl chloride), flax, cotton, resin, glass and fiber glass. In some embodiments, substrate 24’s fibers are used as an indicator layer. Substrat 24 can take many forms. Substrate 24 can be in a variety of forms, including a strip, sheet or string. Substrat 24 may be part of food packaging material, or adhered to food packaging materials in some instances. Substrat 24’s thickness may vary. To reduce the absorption of chemicals from indicator layer 22 on substrates, some embodiments may limit the thickness of the substrate.
Indicator layer 22 usually includes a polymeric matrix with one or more indicator chemicals. Indicator compounds are dye compounds that can colorimetrically indicate the presence of chemical compounds related to the spoilage or decomposition of food. The indicator compounds can be used to indicate the presence of decomposition products at temperatures below freezing. The indicator compounds must be able to detect the presence of decomposition products in the absence or mediation by water.
There are many chemical compounds that can be produced when food spoils or decomposes. Volatile compounds such as volatile bases are generated by foods high in protein, such red meat, pork, poultry and processed meats. One group of volatile bases is the amines. It’s formed by the breakdown of nucleotides and deamination of amino acids. Ammonia, trimethylamine, and dimethylamine are just a few of the amines that can be generated. Even in frozen foods, dimethylamine and trimethylamine can be at least partially volatilized. Histimine, cadaverine and putrescine are all amines that can be associated with food decomposition. These compounds can also volatilize. These compounds and others make up the total amount organic bases formed in the food decomposition process.
Indicator layer 22 generally changes color in the presence volatile bases. The exact range of volatile bases that can cause color changes in an indicator compound will depend on several factors. These include the type of indicator compound being used, the chemical environment where it is placed (e.g. acidity or basicity) and how much indicator is being used. For each food product, the appropriate range can be determined by calibration using test samples. Different food products may produce different levels of volatile bases after spoilage. Food products may produce similar amounts of volatile base even though they are of similar quality (e.g. different types of fish).
The indicator compound’s color may change depending on the concentration of generated volatile bases. This can indicate many conditions. The color change could indicate, for example, that the food is not safe for consumption or will soon be unfit for human consumption.
In some embodiments, an unwanted amine-producing biologic agent such as bacteria or yeast may be detected in addition to or instead of food decomposition. An indicator compound that changes color may be an indication of an unwelcome biological agent such as bacteria or mushrooms. Certain fungi, for example, can produce amines in contact with grains. Trimethylamine is produced by smut from unprocessed wheat that has been stored in silos, or in the cargo hold of ships. While the invention has been described in relation to food decomposition detection, it is clear that the same principles, devices and methods can also be used to detect unwanted biological agents.
Indicator compounds used in the present invention usually have a color change ranging from pH 1.0 to pH 6.0 and, preferably, between pH 2.5 and pH 5.0 in an aqueous solution. Ideal indicators are nontoxic and can be used as food dyes or additives. This reduces the risk of the indicator compound leaking from the food quality device. It is preferable that the indicator compounds have been approved for use in food products by a regulatory agency such as the U.S. Food & Drug Administration. The ideal indicators should have strong color changes upon detection of volatile bases. This color change can be seen even by color-blind individuals. These indicators can also be used without these characteristics.
Indicators that are used in the food quality indicator device must be able to change colors at temperatures below freezing point. This means that the indicator’s color-forming chemical reaction with volatile bases emitted from the food does not depend on water mediation. In many cases, pH indicator strips are required to be wetted and placed in contact with an acidic solution. These strips are not sensitive to the bases produced by spoiled fish, as evidenced by experiments.
Xanthene dyes and azo dyes are all suitable indicators. Many of these indicators have phenol functionalities. Many of these indicators can be halogenated or contain acidic functional group such as?SO3,?COOH, or??S(O2)O? Or salts thereof. The most preferred indicators are halogenated dyes like Phloxine B, Rose Bengal or Erythrosine, sulfonated dyes like Metanil Yellow and Congo Red, and sulfonated dyes like Bromophenol Blue and Bromocresol Green. The best indicators for frozen seafood are Bromophenol blue, Rose Bengal, or Phloxine B.Click here to view the patent on Google Patents.