Featured Research

from universities, journals, and other organizations

Fried food risks: Toxic aldehydes detected in reheated oil

Date:
February 22, 2012
Source:
Plataforma SINC
Summary:
Researchers have been the first to discover the presence of certain aldehydes in food, which are believed to be related to some neurodegenerative diseases and some types of cancer. These toxic compounds can be found in some oils, such as sunflower oil, when heated at a suitable temperature for frying.

At frying temperature, sunflower oil produces more harmful compounds than olive oil.
Credit: SINC

Researchers from the University of the Basque Country (UPV/EHU, Spain) have been the first to discover the presence of certain aldehydes in food, which are believed to be related to some neurodegenerative diseases and some types of cancer. These toxic compounds can be found in some oils, such as sunflower oil, when heated at a suitable temperature for frying.

Related Articles


"It was known that at frying temperature, oil releases aldehydes that pollute the atmosphere and can be inhaled, so we decided to research into whether these remain in the oil after they are heated, and they do" María Dolores Guillén, a lecturer in the Pharmacy and Food Technology Department at the UPV, said.

The researcher is a co-author of a project that confirms the simultaneous presence of various toxic aldehydes from the 'oxygenated α, β-unsaturated group' such as 4-hydroxy-[E]-2nonenal. Furthermore, two have been traced in foods for the first time (4-oxo-[E]-2-decenal and 4-oxo-[E]-2-undecenal).

Until now these substances had only been seen in bio-medical studies, where their presence in organisms is linked to different types of cancer and neurodegenerative diseases such as Alzheimer's and Parkinson's.

The toxic aldehydes are a result of degradation of the fatty acids in oil, and although some are volatile, others remain after frying. That is why than be found in cooked food. As they are very reactive compounds they can react with proteins, hormones and enzymes in the organism and impede its correct functioning.

The research, which is published in the Food Chemistry journal, involved heating three types of oil (olive, sunflower and flaxseeds) in an industrial deep fryer at 190 ºC. This was carried out for 40 hours (8 hours a day) in the first two, and 20 hours for the linseed oil. The latter is not normally used for cooking in the west, but it has been chosen due to its high content in omega 3 groups.

More toxic aldehydes in sunflower oil

After applying gas chromatography/mass spectrometry techniques, the results show that sunflower and linseed oil (especially the first) are the ones that create the most toxic aldehydes in less time. These oils are high in polyunsaturated fats (linoleic and linolenic).

Adversely, olive oil, which has a higher concentration of monounsaturated fats (such as oleic), generate these harmful compounds in a smaller amount and later.

In previous studies, the same researchers found that in oils subjected to frying temperatures, other toxic substances, alkyl benzenes (aromatic hydrocarbons) were found. They concluded that of the oils studied, olive oil is the one that creates the least.

The dose makes the poison

"It is not intended to alarm the population, but this data is what it is, and it should be taken into account" Guillén highlights, who points out the need to continue researching to establish clear limits regarding the risk of these compounds. "On some occasions the dose makes the poison" the researcher reminds us.

Spanish regulations that control the quality of heated fats and oils establish a maximum value of 25% for polar components (degradation products coming from frying). Nonetheless, according to the new study, before some of the oils analysed reach this limit, they already have a "significant concentration" of toxic aldehyde.

The study counts all the aldehydes (not the just the harmful ones) that are generated during frying. Furthermore, the authors present a model that allows the prediction of how any hypothetical oil will evolve in the same conditions, if they know its initial fatty acid composition.


Story Source:

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


Journal Reference:

  1. Maria D. Guillén, Patricia S. Uriarte. Aldehydes contained in edible oils of a very different nature after prolonged heating at frying temperature: Presence of toxic oxygenated α,β unsaturated aldehydes. Food Chemistry, 2012; 131 (3): 915 DOI: 10.1016/j.foodchem.2011.09.079

Cite This Page:

Plataforma SINC. "Fried food risks: Toxic aldehydes detected in reheated oil." ScienceDaily. ScienceDaily, 22 February 2012. <www.sciencedaily.com/releases/2012/02/120222093508.htm>.
Plataforma SINC. (2012, February 22). Fried food risks: Toxic aldehydes detected in reheated oil. ScienceDaily. Retrieved November 24, 2014 from www.sciencedaily.com/releases/2012/02/120222093508.htm
Plataforma SINC. "Fried food risks: Toxic aldehydes detected in reheated oil." ScienceDaily. www.sciencedaily.com/releases/2012/02/120222093508.htm (accessed November 24, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Monday, November 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

AFP (Nov. 23, 2014) — The arable district of Kenema in Sierra Leone -- at the centre of the Ebola outbreak in May -- has been under quarantine for three months as the cocoa harvest comes in. Duration: 01:32 Video provided by AFP
Powered by NewsLook.com
Don't Fall For Flu Shot Myths

Don't Fall For Flu Shot Myths

Newsy (Nov. 23, 2014) — Misconceptions abound when it comes to your annual flu shot. Medical experts say most people older than 6 months should get the shot. Video provided by Newsy
Powered by NewsLook.com
WFP: Ebola Risks Heightened Among Women Throughout Africa

WFP: Ebola Risks Heightened Among Women Throughout Africa

AFP (Nov. 21, 2014) — Having children has always been a frightening prospect in Sierra Leone, the world's most dangerous place to give birth, but Ebola has presented an alarming new threat for expectant mothers. Duration: 00:37 Video provided by AFP
Powered by NewsLook.com
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

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

 

Health & Medicine

Mind & Brain

Living & Well

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