Invisible, biodegradable markers that can carry up to the amount of information in a bar code and that can be placed directly on or within edible materials could provide several benefits to the food industry.

First, they could be used to make food more secure, by providing proof at any point along the production, storage, and distribution chain that a food product is what the label on its package says it is. Second, they could be used to make food safer, by providing similar proof that a food pr…

Fig. 2—50-mm × 50-mm block of a spool of fibers, mounted on a microtome chuck. The mounting is eccentric because the standard microtome blade is 110 mm long. After approximately 10,000 sections are cut, the blade can be moved to the viewer’s right, and the other half of the blade can be used to cut an additional 10,000 sections.

Fig. 3—Illustration of an algorithm for decoding a marker. The marker nearest the bottom right corner of Fig. 3a is isolated in Fig. 3b, and the distance in pixels from its center to its edge at half-degree radians is plotted in Fig. 3c. The large depression third from left is the mouth; the eye is not shown in this graph. The two serrations on either side of the mouth do not project far enough out from their adjacent troughs to form a distinct peak, so the algorithm interprets them as zeros. The nine longer serrations are interpreted as ones, so the code on this marker is 01111111110 or 1,022.

Fig. 5—A marker situated on a Perigord truffle.

Fig. 6—A marker situated on a spinach leaf. The marker was applied in a spray of a treatment applied to vegetables to control the growth of pathogenic bacteria.

Premium Content
You've reached your monthly limit of free articles.
Access Food Technology
Log in Subscribe