Boiling Your New Kitchenware

My mother always boils new glasses and plates. Says it made them stronger.

Well…

Just a couple of months ago I had a laboratory experiment in polymer making. The goal was to make  urea-formaldehyde, which was mostly used as adhesives in plywood industries, for laminating, coating, molding, casting, lacquers, textile finishing, etc. Urea-formaldehyde is a thermosetting plastics or termosets, which is a class of polymers that are irreversibly cured (by heat, hence the name). After it is cured, it is resistant to acid and base, and cannot be melted nor re-shaped. It cannot, therefore, be recycled.

But the polymer used in kitchenware is not urea-formaldehyde, it is its brother, melamine-formaldehyde. Somehow, during the meetings with the module lecturer who is ever so obscure (although thankfully not annoying…he has the assistant who is already too annoying), we got into talking about kitchenware.

“What are kitchenwares made of?”

“Um…glass?”

“No. Polymers. The ones you can put in a microwave.”

“Um…melamine?”

“That’s right. Now, what did you do before using them?”

“Um…”     *contemplate on whether or not to answer “Clean them”, but then again, that sounds too stupid even for me*

“What would the elderlies do?”

Now he’s asking what my Grandma would do?

“Boil them?”

“Yes, that’s right. Do you know why?”

“…..”

Apparently, it is to release the formaline in the kitchenware. In the process of making melamine-formaldehyde, melamine and formaldehyde are mixed, just like in the process of makin urea-formaldehyde, urea and formaldehyde are mixed.
And of course, there is always an excess of reagents. In this case, excess formaldehyde (a.k.a formalin, the chemical used to preserver biological specimen which includes dead people, will vaporized in heat. The formalin is trapped in the solid structure of the melamine-formaldehyde polymer, but will be release when the formalin turns into vapor and leaves the solid 3-D structure into the air.

This happens when heat is involved, say…when you put hot meal into your brand new melamine plate. The formalin released will then be absorbed by you. That will not do, will it?

That is why we boil new plate and glasses.

2.0.01 Ejector

My first laboratory experiment of this semester:

An ejector, or injector, or steam ejector or steam injector is a device used to transport fluid (the suction fluid) using the motion of another fluid (motive fluid).

So an ejector works like this: A high-pressure motive fluid is flowed through a nozzle (preferably a convergent nozzle), and the nozzle converts the pressure energy of a motive fluid into velocity energy, and a low pressure zone is created in front of the nozzle, since the motive fluid is expanded (V>>> therefore P<<<). This low pressure zone then draws in the suction fluid.

After passing through the mixing chamber of the ejector, the mixed fluid expands and the velocity is reduced, resulting in the recompression of the mixed fluid (by converting velocity energy back into pressure energy).

The motive fluid may be a liquid, steam or any other gas. The suction fluid may be a gas, a liquid, a slurry, or a dust-laden gas stream.

The diagram below depicts a typical modern ejector. It consists of a motive fluid inlet nozzle and a converging-diverging outlet nozzle.

Water, air, steam, or any other fluid at high pressure provides the motive force at the inlet. The Venturi effect, a particular case of Bernoulli’s principle, applies to the operation of this device. Fluid under high pressure is converted into a high-velocity jet at the throat of the convergent-divergent nozzle which creates a low pressure at that point. The low pressure draws the suction fluid into the convergent-divergent nozzle where it mixes with the motive fluid. In essence, the pressure energy of the inlet motive fluid is converted to kinetic energy in the form of velocity head at the throat of the convergent-divergent nozzle. As the mixed fluid then expands in the divergent diffuser, the kinetic energy is converted back to pressure energy at the diffuser outlet in accordance with Bernoulli’s principle.

A bit confused? So am I… >.<

Is It Them?

In Boston Legal season 2, an overly-obese man was persuaded to sue a snack company for making him fat. He claimed that the snack (I forgot the name, it’s some sort of cake) made him addicted and as a child he devoured up to 3 boxes (!) of that snack in one effing day.

I thought that this was another joke from Boston Legal. The senior partner who handled this case IS crazy and just got out of the hospital. I thought, “That man can’t control his appetite and he’s suing the snack company? If he wins, this world is really insane. If he can even make a case, it’s absurd.”

Then Shirley Schmidt made her argument. She listed all the ingredients of the snack; the colouring which is metal-based and of course unhealthy, preservatives, etc, then she came to high fructose corn syrup. She said that this corn syrup inhibits the production of leptin, and leptin is the hormone that tells our brain that we are full and that we should stop eating.

Naturally, I forgot about it for a while, UNTIL…I went grocery-shopping in the supermarket (I don’t really buy grocery, but it’s still called grocery-shopping, right?). I had taken a bag of chocolate marshmallow and was about to put it in the basket when a sudden thought stopped me. I remembered Shirley Schmidt and what she said, and I recall how I can eat the whole bag in one day if only my mind doesn’t scream, “Are you nuts!?  You really want to eat all that sugar? Do you want to get diabetes?”

But the thing is, eating marshmallow is like an addiction. Well, not really an addiction. It’s…uhm…you want to eat the second one after you ate the first one, and the third after the second. At least that’s what happen with me and marshmallows.

So I skimmed through the ingredient list, and there it was, seemingly innocent: high fructose corn syrup.

I decided that marshmallows might not be a great idea. I want to do some research first.
And I found out that it’s all true. I read the American Journal of Clinical Nutrition, and found that high fructose corn syrup indeed reduces the concentration of leptin.

“…, a low insulin concentration after ingestion of fructose would be associated with lower average leptin concentrations than would be seen after ingestion of glucose. Because leptin inhibits food intake, the lower leptin concentrations induced by fructose would tend to enhance food intake. This is most dramatically illustrated in humans who lack leptin. Persons lacking leptin (homozygotes) are massively obese, and heterozygotes with low but detectable serum leptin concentrations have increased adiposity, which indicates that low leptin concentrations are associated with increased hunger and gains in body fat.“
Click here for the full journal.

Right now, more food and beverages are using high fructose corn syrup as a sugar substitute. The manufacturers claimed that the corn syrup is natural. True, it might be more natural than aspartame or saccharin. But I personally will try to eat less products with corn syrup in it, since researches are still ongoing and showing the corn syrup bad effects for our health.
http://www.sprol.com/?p=236
http://www.time.com/time/health/article/0,8599,1841910,00.html
http://www.mayoclinic.com/health/high-fructose-corn-syrup/AN01588

Melamine Alert!

What is melamine?
Melamine is an organic base which has the chemical formula C₃H₆N₆ and has the IUPAC name 1,3,5-triazine-2,4,6-triamine. It is only slightly soluble in water.

Chemical Structure of Melamine

Melamine is a trimer of cyanamide, and like cyanamide it consisted 66% of nitrogen (by mass).

In China, melamine was found to have contaminated several milk products.
In September 2008, Sanlu recalled all powdered milk in the China’s Gansu province where melamine was reported to have been used in 22 brands of infant formula, resulting in more than 53,000 ill infants and hopitalizing almost 12,9000. Melamine has also been found in the products produced by Yili Industrial Group Co.

As of 18 September 2008 there had been four confirmed infant deaths that were caused by this contamination. Those who survived were diagnosed with acute kidney failure.

Melamine was supposed to be made into plates, etc. What are they thinking, adding it into milk??
In China, water has been added to raw milk to increase its volume. As a result of this adulteration, the milk has a lower protein concentration. Therefore, the companies that use milk for further production (e.g. powdered infant formula) started checking the protein level through a test that measures the nitrogen content (nitrogen is present in amino acids, and therefore it is also present in proteins). Adding melamine will therefore increases the nitrogen content of the milk, and will ‘fool’ the protein test.

Of course, no test for melamine had been conducted since there had been no reason whatsoever to suspect the addition of this ingredient.

Allegedly, someone in the supply chain, milk supplier or manufacturer, is adding the one adding melamine to milk formula. They may have make themselves a nice little profit, but at what cost?

According to Badan POM Indonesia, these 28 products are contaminated:

1. Jinwel Yougoo Susu Fermentasi Rasa Jeruk
2. Jinwel Yougoo Aneka Buah
3. Jinwel Yougoo tanpa Rasa
4. Guozhen susu bubuk full cream
5. Meiji Indoeskrim Gold Monas Rasa Cokelat
6. Meiji Indoeskrim Gold Monas Rasa Vanila
7. Oreo Stick Wafer
8. Oreo Stick Wafer (disebut dua kali, karena ukuran berbeda)
9. Oreo Cokelat Sandwich Cookies
10. M&M’s Kembang Gula Cokelat Susu
11. M&M’s Cokelat Susu
12. Snicker’s (biskuit-nougat lapis cokelat)
13. Dove Choc Kembang Gula Cokelat
14. Dove Choc
15. Dove Choc (disebut dua kali, karena ukuran berbeda)
16. Natural Choice Yoghurt Flavoured Ice Bar
17. Yili Bean Club Matcha Red Bean Ice Bar
18. Yili Bean Club Red Bean Ice Bar
19. Yili Prestige Chocliz
20. Yili Chestnut Ice Bar
21. Nestle Dairy Farm UHT Pure Milk
22. Yili High Calcium Low Fat Milk Beverage
23. Yili High Calcium Milk Beverage
24. Yili Pure Milk 205 ml
25. Yili Pure Milk 1 L
26. Dutch Lady Strawberry Flavoured Milk
27. White Rabbit Creamy Candy
28. Yili Choice Dairy Frozen Yoghurt Bar (kembang gula)

BPOM stated that the products banned were ones produced overseas, not the ones produced here. But just to be safe, lay off the oreo…

Sources:
http://www.who.int/csr/media/faq/QAmelamine/en/index.html
http://www.sciencebase.com/science-blog/melamine-in-milk.html
http://planet-bekasi.web.id/index.php?/archives/1844-28-Produk-Makanan-Ditarik,-Akan-diteliti-apakah-ada-kandungan-melamin..html

Enzymatic Conversion of Starch Into Glucose Syrup

 

This is my first laboratory activity: converting starch into glucose syrup using enzymes.

Starch is a polysaccharide carbohydrate; a polymer of glucose joined together by glycosidic bonds. Starch consists mainly of amylose and amylopectin; amylose being a relatively linear polymer of glucose joined by α-1,4-glycosidic bond, and amylopectin being a branched polymer of glucose joined by both α-1,4-glycosidic bond (linear) and α-1,6-glycosidic bond (branching) (Caballero, 2003).

To convert this polymer into its monomer, the amylase enzyme is used. The amylase enzyme can be classified into three categories: α-amylase, β-amylase, and glucoamylase. α-amylase will break the α-1,4-glycosidic bond randomly, giving molecules of dextrins. α-amylase can also break the α-1,6-glycosidic bond, but at a much slower rate (usually the enzym pullulanase is added to accelerate the breakage of α-1,6-glycosidic bond). β-amylase breaks the α-1,4-glycosidic bond from the non-reducing end, giving molecules of maltoses. And glucoamylase breaks the α-1,4-glycosidic bond also from the non-reducing end, giving molecules of glucose (Wiseman, 1985).

The α-amylase used is obtained from the bacteria B. subtilis or B. licheniformis, whereas the β-amylase is obtained from Aspergillus sp. and Rhizopus sp.

This conversion took place in a couple of steps:

• First, we make a solution from the starch. In Wiseman (1985), a 30-40% solution w/w is preferred, which will -after the conversion reaction- give a 94-97% glucose in equilibrium mixture.
• Then, we gelatinized this solution. Gelatinization is the process of breaking down the intermolecular bonds if starch molecules in the presence of water and heat.
• After the starch solution is gelatinized (by heating), the solution became very viscous, just like the starch (kanji) we used to stiffen our clothing items. This is where the α-amylase is added, at 90 degrees Celcius and stirred for approximately 2 hours. This is the process of liquefying the starch. See, this α-amylase will break down the α-1,4-glycosidic bond, but not the α-1,6-glycosidic bond. Therefore, the reaction yields molecules of branched but short glucose. Branched molecules are soluble in water, whereas linear ones are insoluble. In other words, the branched molecule will make a less viscous solution that the linear ones. Hence the viscosity of the starch solution will decrease as the α-amylase works (Wiseman, 1985).
• Liquefying can also be done with acid (HCl), in room temperature and acidic condition (pH 4.5-5). The downside of using acid is that acid can hydrolyze protein into amino acid, which will cause the browning reaction (or the Maillard reaction: reaction between amino acid and reducing sugar which will result in the presence of flavour. www.wikipedia.org/wiki/Maillard_reaction). This is of course not desirable, because in order to get a pure glucose (or high concentrated, at least), the starch has to be really rid of impurities, where as an enzymatic reaction is specific and only the starch will be converted.
• After the liquefying process, saccharifying is done with glucoamylase. The temperature for this step is 55-60 degrees Celcius. Saccharifying literally meant to convert into sugar (saccharose). Or, in more scientific words, saccharifying is the process of converting a sugar derivative or complex carbohydrate into a simple soluble fermentable sugar by hydrolysis.
• The conversion is assumed to be done. A sample of the sugar is to be taken repeatedly at a time interval, and analyzed. Here we use the Fehling’s reagent. The Fehling’s reagen consisted of Fehling A (blue, copper sulfate solution) and Fehling B (colorless, potassium hydroxide and potassium sodium tartrate solution). This reagent specifically oxidize reducing sugars (glucose is a reducing sugar), and will result in a change of color from blue to red (cuprous sulfate). A standard solution of pure glucose is used to standarize the Fehling’s reagent.

After obtaining the glucose concentration at every interval of the reaction, these data is plotted according to the Michaelis-Menten kinetics.