Featured Research

from universities, journals, and other organizations

Knowing whether food has spoiled without even opening the container

Date:
March 17, 2014
Source:
American Chemical Society
Summary:
A color-coded smart tag could tell consumers whether milk has turned sour or green beans have spoiled without opening the containers, say researchers. The tag, appearing on the packaging, also could be used to determine if medications and other perishable products were still active or fresh.

The green smart tag on the bottle above indicates that the product is no longer fresh.
Credit: Chao Zhang

A color-coded smart tag could tell consumers whether a carton of milk has turned sour or a can of green beans has spoiled without opening the containers, according to researchers. The tag, which would appear on the packaging, also could be used to determine if medications and other perishable products were still active or fresh, they said.

Related Articles


This report on the color-changing food deterioration tags was presented today as part of the 247th National Meeting & Exposition of the American Chemical Society (ACS). It is being held at the Dallas Convention Center and area hotels through Thursday.

"This tag, which has a gel-like consistency, is really inexpensive and safe, and can be widely programmed to mimic almost all ambient-temperature deterioration processes in foods," said Chao Zhang, Ph.D., the lead researcher of the study. Use of the tags could potentially solve the problem of knowing how fresh packaged, perishable foods remain over time, he added. And a real advantage, Zhang said, is that even when manufacturers, grocery-store owners and consumers do not know if the food has been unduly exposed to higher temperatures, which could cause unexpected spoilage, "the tag still gives a reliable indication of the quality of the product."

The tags, which are about the size of a kernel of corn, would appear in various color codes on packaging. "In our configuration, red, or reddish orange, would mean fresh," explained Zhang, who is at Peking University in Beijing, China. "Over time, the tag changes its color to orange, yellow and later green, which indicates the food is spoiled." The colors signify a range between 100 percent fresh and 100 percent spoiled. For example, if the label says that the product should remain fresh for 14 days under refrigeration, but the tag is now orange, it means that the product is only roughly half as fresh. In that case, the consumer would know the product is edible for only another seven days if kept refrigerated, he explained.

The researchers developed and tested the tags using E. coli (food-spoiling bacteria that cause gastrointestinal problems) in milk as a reference model. "We successfully synchronized, at multiple temperatures, the chemical evolution process in the smart tag with microbial growth processes in the milk," according to Zhang. The tags could also be customized for a variety of other foods and beverages.

The tags contain tiny metallic nanorods that, at different stages and phases, can have a variety of colors: red, orange, yellow, green, blue and violet, Zhang explained. "The gold nanorods we used are inherently red, which dictates the initial tag color," he said. "Silver chloride and vitamin C are also in the tags, reacting slowly and controllably. Over time, the metallic silver gradually deposits on each gold nanorod, forming a silver shell layer. That changes the particle's chemical composition and shape, so the tag color now would be different. Therefore, as the silver layer thickens over time, the tag color evolves from the initial red to orange, yellow, and green, and even blue and violet."

Although the nanorods are made of gold and silver, a tag would still be very inexpensive, and all the chemicals in the tiny tag cost much less than one cent -- $0.002. "In addition, all of the reagents in the tags are nontoxic, and some of them (such as vitamin C, acetic acid, lactic acid and agar) are even edible," he explained.

This technique has been patented in China, and some preliminary results have been published in ACS Nano, Zhang said. He added that the next step is to contact manufacturers and explain how the tag would be useful for them and their customers.

The study was supported by National Natural Science Foundation of China, Hong Kong Research Grants Council and National Basic Research Program of China.

A new video, illustrating how the tag works, is available at http://www.youtube.com/watch?v=y-Fpj9bdht4.


Story Source:

The above story is based on materials provided by American Chemical Society. Note: Materials may be edited for content and length.


Journal Reference:

  1. Chao Zhang, An-Xiang Yin, Ruibin Jiang, Jie Rong, Lu Dong, Tian Zhao, Ling-Dong Sun, Jianfang Wang, Xing Chen, Chun-Hua Yan. Time–Temperature Indicator for Perishable Products Based on Kinetically Programmable Ag Overgrowth on Au Nanorods. ACS Nano, 2013; 7 (5): 4561 DOI: 10.1021/nn401266u

Cite This Page:

American Chemical Society. "Knowing whether food has spoiled without even opening the container." ScienceDaily. ScienceDaily, 17 March 2014. <www.sciencedaily.com/releases/2014/03/140317170638.htm>.
American Chemical Society. (2014, March 17). Knowing whether food has spoiled without even opening the container. ScienceDaily. Retrieved November 22, 2014 from www.sciencedaily.com/releases/2014/03/140317170638.htm
American Chemical Society. "Knowing whether food has spoiled without even opening the container." ScienceDaily. www.sciencedaily.com/releases/2014/03/140317170638.htm (accessed November 22, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Saturday, November 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Could Your Genes Be The Reason You're Single?

Could Your Genes Be The Reason You're Single?

Newsy (Nov. 21, 2014) Researchers in Beijing discovered a gene called 5-HTA1, and carriers are reportedly 20 percent more likely to be single. Video provided by Newsy
Powered by NewsLook.com
Raw: Baby Okapi Born at Houston Zoo

Raw: Baby Okapi Born at Houston Zoo

AP (Nov. 20, 2014) The Houston Zoo released video of a male baby okapi. Okapis, also known as the "forest giraffe", are native to the Democratic Republic of the Congo in Central Africa. Video is mute from source. (Nov. 20) Video provided by AP
Powered by NewsLook.com
Your Complicated Job Might Keep Your Brain Young

Your Complicated Job Might Keep Your Brain Young

Newsy (Nov. 20, 2014) Researchers at the University of Edinburgh found the more complex your job is, the sharper your cognitive skills will likely be as you age. Video provided by Newsy
Powered by NewsLook.com
Mysterious Glow Worms Found in the Amazon

Mysterious Glow Worms Found in the Amazon

Buzz60 (Nov. 20, 2014) Wildlife photographer Jeff Cremer teamed up with entomologist Aaron Pomerantz and others to investigate a predatory glow worm found in the Amazon. Patrick Jones (@Patrick_E_Jones) explains. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins