Posts Tagged ‘milk’

Ginger milk curd

Monday, February 24th, 2014

ginger-milk-curd-syneresis
With only 3 ingredients you can make a tasty gel within minutes. The gel is very fragile and easily “looses” liquid, in this case whey, which is seen as a clear drop under the spoon. This loss of liquid from a gel is known as syneresis.

Some weeks ago, while doing research for Texture on gel formation in foods where no “external” hydrocolloid is added, I came across ginger milk curd (in Chinese: 姜汁炖奶/薑汁撞奶). With only three ingredients – milk, ginger and sugar – it immediately caught my attention. I found a recipe and my first attempt was successful. I was amazed! With three seemingly simple ingredients I was able to form a tender, fragile gel within minutes. I loved the strong ginger taste with a touch of sweetness. After my first success I had several failed attempts, so I looked up some more recipes. What puzzled me was that, as I dug up more recipes, the different instructions were specific, but also contradictive. I couldn’t let go at this point, so I continued reading – also scientific papers. Now that I have a fairly good understanding of the science behind ginger milk curd it is clear that the many recipes I had found were full of kitchen myths. (more…)

Speeding up the Maillard reaction

Friday, September 26th, 2008


Ever thought about how pretzels and salt sticks get their nice brown color?

The products of the Maillard reaction provide tastes, smells and colors that are much desired and lend their charachteristics to a variety of foods. In this post I will focus on the factors that influence how fast the Maillard reaction proceeds. And more specifically I’ll give examples on how the Maillard reaction can be speeded up. This is not about fast food, nor is it about saving time. It’s more about controlling the browning reaction by speeding it up or slowing it down in order to get a desired end result.

The Maillard reaction is, to put it simple, a reaction between an amino acid and a sugar (there’s more on the chemistry at the end of the post). To speed it up you can do one or more of the following:
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Lightstruck flavor in beer

Friday, February 16th, 2007

Some years ago, a group of researches studied the formation of lightstruck flavor in beer (Chem. Eur. J. 2001, 4554). They found that isohumulones, compounds contributing to the bitter taste of beer, decomposed when exposed to ultraviolet light. In a recent blogpost, Harold McGee elaborates on this and it turns out that the way this happens is even more complex than first anticipated. The researchers (J. Agric. Food Chem, 2006, 6123) found that riboflavin (vitamin B2) acts as a photosensitizer in beer (and in olive oil, milk and butter) which catalyzes the conversion of oxgyen to a more reactive type of oxygen (singlet oxygen). This oxygen then “destroys” isohumulone and in the process radicals are formed.

isohumulone1.jpg

As shown in the figure, the radical reacts with sulfur containing proteins, thereby forming a thiol called 3-methylbut-2-ene-1-thiol or just MBT for short. The amazing thing about this compound is that we can smell it at concentrations as low as a few parts per billion (ppb). The perhaps not-so-amazing thing is that this compound gives beer a “skunky” aroma. Obviously one would want to avoid this, and that’s why beer is sold in dark brown glass bottles that act as the beer’s own sunglasses. Canned beer of course will not go skunky (well not until it’s poured into a glass and served outside in bright sunlight – that will turn any beer skunky within minutes).

Unfortunately however, not all beer is sold in dark bottles! One well known brand is shown in the picture below…

corona.jpg

And yes – as you might have figured out, 3-methylbut-2-ene-1-thiol is present in Corona beer (and other brands sold in clear bottles, to a lesser extent MBT is also found in green bottled beer). For some references to “skunky” off flavours in beer check out these links: here, here and here. The ubiquitious slice of lime served with Corona beer is nothing but clever marketing since it helps camouflage the smelly thiol formed! (but how well does lime actually camouflage the thiol aroma?)

The take home message is: keep your olive oil, milk, butter and beer away from sunlight!

Drink your tea without milk!

Wednesday, January 10th, 2007

Experimental and clinical studies indicate that tea exerts protection against cardiovascular diseases. However, a group of German researchers (abstract, European Heart Journal 2007, ASAP contents) have found that the beneficial effects of drinking tea may be reduced if milk is added to the tea.

milk drop hits coffee
(Picture by IreneM entiteld “coffee with a “drop” of milk” from DPchallenge – OK, it’s not tea, but I just love this picture!)

By measuring the blood vessel’s ability to expand (and thereby reduce the blood pressure) the researchers found that this ability was improved by tea, but the effect was completely blunted if milk was added to the tea. It was found that the caseins were responsible for the observed inhibition, probably by formation of complexes with catechins. It is believed that catechins (polyphenolic compounds, belong to the group of flavonoids, structure of epicatechin shown below) trigger the release of other active substances that are responsible for the expansion of blood vessels (also known as vasodilation).

epicatechin

The results of this study are not limited to tea, because catechins are found in many other foods, including citrus fruits, wine and chocolate.