RHEOLOGY GALLERY
INITIATOR: KARIM

Hi everybody, we encounter rheology everyday. Why not snap a picture (using your phone camera) or even a video of all the rheological events that you encounter everday and upload them here.


Yishen Tey:
Here are some photos i took. I think they can be related with rheology behavior. Kindly correct me if I am wrong.
No worries, these are all vegetarian food!

Starch especially corn starch is commonly added soup or gravy to make them thicker, and thus provide the mouth feel.
Recipe tips for you all, to avoid lumps in your dish, mix the starch with an equal amount of cold liquid until it forms a paste, then whisk it into the liquid you're trying to thicken. You then need to simmer the liquid, stirring constantly, for a minute or so until it thickens.
Cornstarch doesn't stand up to freezing or prolonged cooking, and it doesn't thicken well when mixed with acidic liquids(vinegar, limau kasturi ect.) [WHY?].

[Starch can be degraded by chemical degradation, physical alteration, genetic modification, and enzymatic transformation. Acid affect the degree of polymerization of starch. It modifies starch structure by affecting hydrogen bond. In presence of strong acid and heat, the glycosidic bond between the monosaccharide in polysaccharide is cleaved. Here are a link about how acid concentration influence the hydrolysis inside the starch granule : http://www.scipub.org/fulltext/ajas/ajas54307-311.pdf]

Once the thickener is added, cook it briefly to remove the starchy flavor. Don't overcook--liquids thickened with some starches will thin again if cooked too long or at too high a temperature. I think starch, a type of carbohydrate will burnt (hangus) too, I encountered that :-P. [Yes, this is a common phenomenon for starch. You will learn more about starch properties in another course - Karim]
Starch thickeners don't add much flavor to a dish, although they can impart a starchy flavor if they're undercooked. [Cereal starch such as rice or corn can impart some flavour to a dish due to its higher lipid content compared to non-cereal starches such as potato or tapioca - Karim].
Here are some dishes with gravy. [I suggest you rearrange the photos in a table wth 2 or 3 colums -- appear neater - Karim]


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Mee Jawa (I specially requested for some green sawi)

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Mee Chap (In hokkiean, 'Chap' means 'gravy')

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Kungfu Mee (How kungfu is it? Actually the noodle is baked and then served with the gravy, vegetables and tauki)


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Creamy Mushroom Soup.


Now, look at the topping of these 2 layers kuih, ignore the mee or meehun aside. All are the kuih we had during PPSL not long ago. I think the chef is passionate in preparing these "2 layers kuih", we almost had them every day.
The creamy topping is added with starch, tapioca starch if I am not mistaken, santan, flavor eg. corn, yam, pandan or ect.

Tapioca starch is a good choice for thickening pie fillings, since it thickens at a lower temperature than cornstarch, remains stable when frozen, and imparts a glossy sheen. The starch is also sometimes used to thicken soups, stews, and sauces, but the glossy finish looks a bit unnatural in these kinds of dishes. It works quickly, though, so it's a good choice if you want to correct a sauce just before serving it. Some recipes for baked goods also call for tapioca flour because it imparts a chewier texture.

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Kuih Serimuka (Am I right? One of my Malay friend told me)

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Yam type. I was impressed by this, Lee Hoon too. That was the first time we met this. Beautiful! [Taste good also!]

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Who know its name?​(If i not mistaken is kuih taba...very nice!!​)

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Pandan topping with glutinous rice. (specific name?)

The creamy topping with coconut milk give the sweetness and taste.
Rheology behavior? I think it can't be watery, and drop off from the base layer.

Stabilizer and thickener influence the rheology of food.
One of the common gelling agent, thickening agent,and stabilizer, is pectin. The classical application is giving the jelly-like consistency to jams or marmalades. In medicine, pectin increases viscosity and volume of stool so that it is used against constipation and diarrhea. Pectin can also be used to stabilize acidic protein drinks, such as drinking yogurt, and as a fat substitute in baked goods.

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Pectin in jam