tampering with food ingredients

[DaSwede]

Don't know about you lot, but over here we're learning more each day about hydrogenated and partially hydrogenated oils and how detrimental they are to our cardiovascular systems. Another term that often pops up on food ingredients declarations is 'modified starch.' What do we know about that, healthwise? 'Modified' does sound suspiciously like 'hydrogenated.'

Oh and if you want me to understand your reply, don't get too chemical on me...! I have no urge to understand the molecular processes as such, just want to know about it to the extent that it raises health concerns.

Thanks in advance. I'm not here every day but will check in and thank you more personally later this week.

[theprof]

With regard to your modified starch question, in their raw form, starches are sometimes useless to food processors as they do not have the desired properties for certain applications. When slurry of raw starch is heated, the starch granules swell, and then rupture causing unwanted changes in viscosity. After heating, this slurry is too cohesive for most purposes.

Modified starches are produced by a number of methods including acidulation, bleaching, oxidation and others - I've left out the chemical details as per your request. The starches used in the modification process include waxy maize, potato starch and cornstarch.

Following modification, the starch will have developed a number of new properties. This may include a reduction in tendency to gel in solution, increases in viscosity and better freeze-thaw stability. These starches will form a stable suspension in solution without thickening. Heating such solutions results in a predictable increase in viscosity. They also are able to act as binders in food products and are also able to assist with the suspension of fats and oils in solution.

All in all, modified starches have proved to be invaluable in the food processing industry.

That�s the gist of the benefits of modified starch. The modification of starch to modified starch is less intensive from a chemical point of view than the hydrogenation of vegetable oil � again I�ll not provide the chemistry behind it. This may well be the reason why modified starch is generally regarded as an innocuous version of starch by the food lobbyists and they seem to be reasonably happy with the product. All the same, I�m not an expert over this issue and someone may well correct me.

[DaSwede]

Hiya theprof, that's a superb answer, thank you so much.

I'm feeling a bit stupid now about asking people not to get into molecular details, as maybe that is exactly what one would have to do to discuss the possible disadvantages when 'modified' stuff gets into your system and meets up with your own personal molecules. You say that the process is less intensive than the hydrogenation - is it (sometimes) the same kind of process, though? Only less intense?

Please feel free to add on to your reply if by any chance I put a damper on it with my dumb please answer this question but do it my way not yours-request. I'll do my best to understand! May not be here over the weekend, though.

[theprof]

It�s very difficult to answer a question like this without discussing the chemistry involved. I�ll try to simplify it as much as possible.

When starches are modified in the manner I discussed above, only the physical properties of the starch are altered. Limited structural modifications occur to the starch molecules themselves despite the fact that the raw starch may have been in contact with acid, peroxides etc in order to bring about the modification.

This is not the case when it comes to hydrogenation and it is not the same kind of process at all. When I used the word �intense� I was trying to convey that the changes that occur at the molecular level are less in converting starch to modified starch than vegetable oil to hydrogenated vegetable oil. The trouble is, now that I�ve said that, I�m going to have to touch on the chemistry involved.

All the fats that we consume, whether solid or liquid consist of fatty acids and glycerol. In general, fats are referred to as triglycerides. When we digest these fats, they�re broken down into fatty acids and glycerol, which are then used to make other lipids in the body. Fat is stored as triglycerides by the body.

At a molecular level, fatty acids are chains of carbon, hydrogen and oxygen. These chains may be �saturated� or �unsaturated�. The term �saturation� refers to nothing more than the number of hydrogen atoms linked to each carbon atom in the chain.

In fatty acids in which carbon atoms have as many hydrogen atoms as possible attached on the chain, the fatty acid is called saturated.

[theprof]

In fatty acids in which hydrogen atoms are missing in the chain, the fatty acid is called unsaturated. Polyunsaturated fatty acids have two or more missing hydrogen pairs whereas monounsaturated fatty acids are missing only one hydrogen pair on the chain.

It is the fatty acid content of a product that makes one food product different from another. All fats are mixtures of these saturated, polyunsaturated and monounsaturated fatty acids. The proportion of each is responsible for their varying characteristics when you compare oil to margarine for example.

Now fats that are made mainly from saturated fatty acids are solid at room temperature. These will include animal based fats such as butter, some types of margarine, palm �oils� etc. The harder the fat, the more saturated it is.
Fats made from mainly polyunsaturated fatty acids are normally liquid at room temperature. Sunflower oil and Corn oil are two good examples.

Fats made from monounsaturated fatty acids are also liquid at room temperature. Peanut oil and olive oil are typical examples.

[theprof]

Right, that�s the lecture on fat types over. Now let�s deal with hydrogenation.

In very simple terms, hydrogenation is the process of passing hydrogen through heated oil. During this process, the fatty acids in the oil acquire some of the hydrogen and the oil rapidly becomes denser. Now you�d be correct to think that what�s happening here is that the unsaturated oil is becoming progressively more saturated as more hydrogen is passed through it. In fact, if sufficient hydrogen were passed through, it would solidify into a saturated fat.

Usually fats are not required to be fully saturated as sufficient types occur naturally. Instead, sufficient hydrogen is passed through the vegetable oils to make what is known as partially hydrogenated vegetable oil. These partially hydrogenated vegetable oils are neither solid nor liquid, and have a consistency similar to butter. However, the important part is to note that these products will have cost a fraction of the cost of natural saturated fat to produce.

In this way, oils can be converted to margarines etc at reasonable cost. Adjusting the hydrogenation of the product will alter such properties as melting points and spreadability.
Partially hydrogenated vegetable oils also have longer shelf-lives than natural saturated fats due to oxidative stability and they give a better texture to baked products.

[theprof]

That�s the end of the hydrogenation lecture. Now to the health implications and regrettably, more advanced chemistry (apologies!)

Unsaturated fatty acids in foods exist chiefly in what is known as the cis configuration. This has all to do with the molecular structure of the molecule. In the cis configuration, hydrogen atoms are all on the same side of the double bond of the molecule. When fats and oils are partially hydrogenated, a number of hydrogen atoms will have attached themselves on the opposite side of the double bond. The resulting molecules are known as trans fatty acids and these are the ones that are said to be harmful. (If you can�t visualise this, try looking up cis and trans in wikipedia etc � the diagrams will make it clearer)

Trans isomers have been implicated in circulatory and heart diseases for many years although the precise mode of action of these isomers is not understood. It is these trans fatty acids that have been the target of food lobbyists for years, and because of this partially hydrogenated vegetable oils are off the menu for them despite the fact that they occur in small amounts naturally in milk, butter etc.

[DaSwede]

The prof, you're unbelievably kind to have written this whole Food Processing for Dummies for me - thank you very very much. And I actually got most of it - thanks to your pedagogical virtues. So kind!

I'm getting you one of these, whether you want one or not! And a gold star.

[theprof]

I'm happy to have helped you and thanks for the compliment.

I like the T-shirt - I think I'll buy one myself and raise some eyebrows at the university!