Featured Research

from universities, journals, and other organizations

Cold Temperature Is Key To Quality Of Bagged Salads

Date:
July 29, 2008
Source:
USDA - Agricultural Research Service
Summary:
Scientists have found that proper storage temperatures are essential to minimize bacterial growth and adaptability inside sealed, bagged salads. They have been studying the safety of new technologies that extend the shelf life of bagged salad greens.

Microbiologist Arvind Bhagwat withdraws a gas sample from bagged lettuce stored under modified atmosphere packaging in a film that restricts oxygen transmission.
Credit: Photo by Peggy Greb

Agricultural Research Service (ARS) scientists have found that proper storage temperatures are essential to minimize bacterial growth and adaptability inside sealed, bagged salads. They have been studying the safety of new technologies that extend the shelf life of bagged salad greens.

The work was conducted by microbiologist Arvind Bhagwat with the ARS Produce Quality and Safety Laboratory in Beltsville, Md. He first investigated differences in bacterial growth levels on cut lettuce leaves that had been bagged under very low oxygen levels--an atmosphere known to extend the time that bagged salad appears fresh.

Bhagwat investigated whether the lack of oxygen would make it harder for the bacteria to survive a synthetic gastric juice shock, which mimics the challenge of exposure to human stomach acids. It turns out that the bacteria sitting on vegetables packed in low-oxygen atmospheres were more likely to survive such a shock.

In response to the challenge of being in an air-starved environment, together with the added nutrients provided by the cut leaves, the bacteria became hardier during storage. This increased hardiness only took place when the bagged fresh-cut salad was left at room temperature or unrefrigerated for extended periods of time.

Bhagwat next tested different temperatures. Bacteria were applied to fresh-cut lettuce and stored in sealed bags under different atmospheric conditions for eight days. When stored under very low-oxygen conditions--and warmer temperatures--bacteria showed more resistance towards synthetic gastric juice.

The findings underscore a danger involved in inadvertently leaving fresh-cut produce at temperatures of 59 degrees Fahrenheit or higher, particularly when low oxygen levels are used to extend the shelf life of fresh bagged lettuce, according to Bhagwat. Consumers are advised to keep refrigerator temperatures at 40 degrees F or below, according to experts.


Story Source:

The above story is based on materials provided by USDA - Agricultural Research Service. Note: Materials may be edited for content and length.


Cite This Page:

USDA - Agricultural Research Service. "Cold Temperature Is Key To Quality Of Bagged Salads." ScienceDaily. ScienceDaily, 29 July 2008. <www.sciencedaily.com/releases/2008/07/080724214520.htm>.
USDA - Agricultural Research Service. (2008, July 29). Cold Temperature Is Key To Quality Of Bagged Salads. ScienceDaily. Retrieved April 19, 2014 from www.sciencedaily.com/releases/2008/07/080724214520.htm
USDA - Agricultural Research Service. "Cold Temperature Is Key To Quality Of Bagged Salads." ScienceDaily. www.sciencedaily.com/releases/2008/07/080724214520.htm (accessed April 19, 2014).

Share This



More Plants & Animals News

Saturday, April 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Vermont Goat Meat Gives Refugees Taste of Home

Vermont Goat Meat Gives Refugees Taste of Home

AP (Apr. 18, 2014) Dairy farmers and ethnic groups in Vermont are both benefiting from a unique collaborative effort that's feeding a growing need for fresh and affordable goat meat. (April 18) Video provided by AP
Powered by NewsLook.com
Man Claims He Found Loch Ness Monster With... Apple Maps?

Man Claims He Found Loch Ness Monster With... Apple Maps?

Newsy (Apr. 18, 2014) Andy Dixon showed the Daily Mail a screenshot of what he believes to be the mythical beast swimming just below the lake's surface. Video provided by Newsy
Powered by NewsLook.com
First Ever 'Female Penis' Discovered In Animal Kingdom

First Ever 'Female Penis' Discovered In Animal Kingdom

Newsy (Apr. 18, 2014) Not only are these newly discovered bugs' sex organs reversed, but they also mate for up to 70 hours. Video provided by Newsy
Powered by NewsLook.com
Little Progress Made In Fighting Food Poisoning, CDC Says

Little Progress Made In Fighting Food Poisoning, CDC Says

Newsy (Apr. 18, 2014) A new report shows rates of two foodborne infections increased in the U.S. in recent years, while salmonella actually dropped 9 percent. Video provided by Newsy
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:
from the past week

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