A while ago a reader sent me a very interesting question regarding a gelled seafood sauce. It is made by mixing tomato ketchup with horseradish and his question was very simple: Why and how does this sauce gel? He speculated about pectin (which is present in tomatoes), but wondered why ketchup then doesn’t gel on it’s own? And he also noted that horseradish ground with water does not have any gel like properties. So how come they can form a gel when mixed together?


Grated horseradish

The first thing that came to my mind was a previous blogpost on tomato gels with the pectin that’s there. Pectin in tomatoes is highly methylated (HM), meaning that a lot of sugar would be required for it to gel and that gelling is not promoted by calcium. But if it is mixed with juice from carrots or oranges which contain the enzyme pectin methylesterase (PME), the methyl groups are cleaved off (as shown below) to yield a low methylated (LM) type of pectin which will gel more easily, especially in the presence of calcium ions. Could something similar be the case in the gelled seafood sauce?

Once horseradish is cut, enzymes start to break down sinigrin to release allyl isothiocyanate (mustard oil) which is responsible for the pungent taste and the irritating effect on the eyes and sinuses. In biochemistry, horseradish is best known for an enzyme called horseradish peroxidase. I’m not sure if this is the enzyme that is responsible for the degradation of sinigrin, but adding together the bits and pieces my best guess is that some enzyme in horseradish does more or less the same thing as pectin methylesterase, cleaving of methyl groups to make the pectin more prone to gel. I haven’t been able to find any papers on this though, so if any readers know more about his – please feel free to fill me inn! And can you think of other foods where horseradish advantageously could be used for gelling?

Using an Aeropress as a pressure filter to obtain a horseradish extract

Before writing this blog post I wanted to test the gelling, so I took a pieces of horseradish, peeled it and grated it. The gratings were quite dry so I decided to mixed them with some water and then filter the mixture to obtain a horseradish extract. The Areopress coffee maker turned out to be perfect for this (as shown in the picture above). I then mixed the extract with approximately 6-8 times the amount of ketchup and left it in the fridge to gel. A before-and-after picture of the ketchup mixed with the horseradish extract is shown below. If I would make this again however, I’d probably not bother about filtration – instead I would use a food processor with knives to break up the cells in the horseradish as much as possible to maximize the release of the intracellular enzymes.

Ketchup and horseradish extract immediately after mixing (left) and after a night in the fridge (right)

The suggested recipe I received with the question was as follows (more can be found by googling “seafood sauce” or “cocktail sauce” in combination with ketchup and horseradish):

Gelled seafood sauce
250 mL horseradish
4 L ketchup to
25 mL lemon juice

Grate/grind horseradish with a little water. Mix with ketchup. Adjust with lemonjuice (and possibly salt) to taste. Refridgerate. The gelling doesn’t happen until a day or so later.

An updated version of “Texture – A hydrocolloid recipe collection” is now available for download (version 2.3). The longer I work on this, the more I realize that it will never really “finish” – there’s always more to add. And believe me – my todo list is still quite long (and I even have some feedback which I haven’t had time to incorporate yet). But I thought that since it’s more than a year since the last update, it was about time to share with you the things that have been changed. Major changes and updates include:

Pictures: This is the biggest visual change! Some recipes are now equipped with pictures which may give you an idea of the texture AND they indicate that the recipe has indeed been tested. But I need your help to add more pictures to the recipe collection (please follow the link to read more about how you can contribute pictures)! And of course - a big thanks to those of you who have already contributed your pictures!

Recipes: Recipes have been added and the total number is about 310 now. I’m getting a little more picky now with regards to which recipes I add. Ideally each new recipe added now should illustrate something new.

I should mention that I’m very grateful for feedback from readers and users of this recipe collection. Thank you very much with helping me improve the document! If you find typos, wish to comment on something or have suggestions on how to improve the collection, please do not hesitate to write me an email at webmaster (at) khymos (.) org or just write a comment in the field below.

Please head over to the download page for the links.

Making gels with fruits that are high in pectin is not particularily challenging. Addition of sugar promotes pectin gel formation with low methoxyl (LM) pectin, but the drawback is that you need a lot of sugar, typically around 50%. So this is only relevant for jams and marmelades. And if you try to gel tomatoes or carrots you may find this quite challenging, even if you add sugar. The approach chosen by Thomas Duvetter, a post doctoral researcher at Laboratory of Food Technology at Katholieke Universiteit Leuven, was to use the pectin methyl esterase enzymes (PME) naturally present in tomatoes, carrots and oranges. The role of PME is to cleave of methyl groups, hence leaving the pectin more prone to calcium induced gelling. Equipped with this knowledge Jean Yves Wilmot presented a number of gels made with the pectin that’s already there.

In order to achieve this one must consider one important thing: tomatoes have another enzyme as well, a polygalacturonase (PG), which causes some trouble. If I got it right this enzyme degrades the pectin gel (and plays an important role in the ripening of tomatoes). One therefore needs to inactivate the tomato PG enzyme and this is done by heat. Regrettably this also knocks out the PME of tomato, but this is were the carrots and oranges come in – they have PME, but no PG. Hence they hold the key to unlock the gelling properties of tomato. So to sum it up, you can use enzymes present in carrot and orange juice to chemically change the pectin of tomatoes to make it more prone to gelling in the presence of calcium ions. If you’re familiar with traditional pectin, what the enzyme does is to make LM pectin out of HM pectin.

Some scientific papers co-authored by Thomas Duvetter which may be of interest:

Isabel Verlent, Ann Van Loey, Chantal Smout, Thomas Duvetter, Binh Ly Nguyen, Marc E Hendrickx “Changes in purified tomato pectinmethylesterase activity during thermal and high pressure treatment” J. Sci. Food. Agric. 2004, 84 (14), 1839.

Ruben P. Jolie, Thomas Duvetter, Ken Houben, Elke Clynen, Daniel N. Sila, Ann M. Van Loey and Marc E. Hendrickx “Carrot pectin methylesterase and its inhibitor from kiwi fruit: Study of activity, stability and inhibition” Inn. Food Sci. Em. Technol. 2009, 10 (4), 601.

Ilse Fraeye, Thomas Duvetter, Eugénie Doungla, Ann Van Loey and Marc Hendrickx “Fine-tuning the properties of pectin–calcium gels by control of pectin fine structure, gel composition and environmental conditions” Trends Food Sci. Technol. 2010, in press.

-

This is part 6 of my report from The Flemish Primitives in 2010. Apart from an overview of the event (part 1) there was quite some inspiration from Asia this year (part 2 and 3). You can also read an interview with Bernard Lahousse, the project leader of The Flemish Primitives (part 4) and I’ve also written about a number of gadgets shown (part 5).

I also visited The Flemish Primitives in 2009. You can read more about that in my four posts from last year: The Flemish Primitives: A travel report (part 1), Chocolate surprise (part 2), Heston Blumenthal (part 3) and Glowing lollipops (part 4). Final note to readers: This year my travel expenses were covered by TFP and the tourism bureau of Brugge.

A picture is worth a thousand words, and this is also true for recipes. Several of you who have downloaded “Texture – A hydrocolloid recipe collection” have asked for pictures and now it’s time to do something about that! A picture can illustrate texture well and is an excellent supplement to the descriptions. I therefore invite to you to contribute to the recipe collection by taking pictures to accompany the recipes. But before you run to grab your camera, please take a note of the following:

• Pictures should clearly show the component described in the recipe. If you take a close up picture against a neutral background it’s good if one still has a feeling of what the scale is.
• Only send a picture if you actually followed the recipe! This way the picture can also serve as an indication that the recipe as been tested. However, if you for some reason have modified a recipe for a better or different result I would also be very interested in hearing about this.
• Pictures should be in focus and well lit. But remember that Photoshop can do wonders, so please do send pictures even though the colors seem a little dull.
• Pictures will be cropped to a 1:1 aspect ratio as shown above
• Preferred minimum resolution is 450 x 450 pixels
• It’s a requirement that the picture is taken by you and that you are willing to provide it for use in “Texture – A hydrocolloid recipe collection” under a Creative Commons Attribution – Noncommercial-Share Alike 3.0 Unported License since the whole recipe collection is published under such a license
• I reserve the right to crop pictures and do color/brightness/sharpness adjustments
• I reserve the right not to use pictures received (and I only intend to include one picture for every recipe)
• Pictures will be attributed to the photographer as shown in the above illustration.

If you have read the above and agree you’re ready to send your texture pictures to me at this email address: texture.pictures (at) gmail.com. Remember to include the name of the recipe photographed and your name as it should appear under the picture. Thank you very much for helping me make this collection even more useful

As I mentioned in the previous post I put the leftover rose froam from TGRWT #16 in the freezer and was surprised by the result. Inspired by this I thought I would extend this and substitute apple juice for water for TGRWT #17. As apple juice is quite sweet I started off with 20 g sugar, but once frozen it lacked sweetness and even was a litte icy, so I upped the amount to 40 g. The picture above may suggest that the foam could be served for dessert, but read the verdict before you make huge amounts of the foam.

Frozen rosy apple foam
2.1 g xanthan (0.50%)
3.6 g methyl cellulose (0.85%)
40 g sugar
6.5 g rose water
300 g apple juice
70 g lemon juice

Grind xanthan, methyl cellulose and sugar in mortar (easier dispersion of hydrocolloid in water). Mix liquids in a bowl and disperse sugar and hydrocolloids into solution with a hand held immersion blender. For better foam production change to tilted disk attachmend or use an electric whisk. Freeze.

Verdict: Aroma wise I was quite satisfied and even my wife liked it. The rose flavor was pronounced but not overwhelming and balanced nicely with the apple. I had to use quite a lot of lemon juice though to get it acidic enough for my taste. The texture was not as smooth as I had hoped for however. It was a little icy and even brittle when scooped and certainly need improvement if I’m to make this again. Another disappointment was the aftertaste – it was actually not good at all. I suspect that it’s one of the hydrocolloids. Anyone have similar experiences? As it is now I would not serve the frozen foam as a dessert because of the aftertaste. But it could work well as an element in a dish. And I was thinking if adding a little fat, for instance as cream, could help both the texture and remedy the aftertaste?

I only used my new Bamix for dispersion and whipping this time. First with the knife attachment for dispersion (top left) and then with the tilted disk for whipping (top right). Compared with the rose foam I made for TGRWT #16 using a conventional hand mixer the bubble size was more non-uniform when using the Bamix (bottom left). The foam scoops nicely when frozen, but texture leaves a little to desire (bottom right).

Just a small reminder that the deadline for the current round of TGRWT #17 is a little later than usual: May 8th. I took the picture above for last month’s TGRWT (where it was combined with chicken) and came to think that it actually qualifies for this month’s TGRWT as well. It’s rose foam on a spoon with apple, celery and almonds, and the foam is sprinkled with a little pepper.

As an experiment I tried to freeze the leftover rose foam and was quite surprised by the resulting texture. It was easy to scoop due to the incorporated air and had a nice mouth feel. There were no ice crystals and the texture was almost a little chewy. What would one call this? Ice cream? Sorbet? No – there is no cream and the texture is much lighter. Frozen sorbet? Foamed sorbet? Frozen foam? Any suggestions? I think I’ll make a variation of the frozen foam for TGRWT #17

Frozen rose foam

Frozen rose foam is easily scooped due to all the air bubbles

For this month’s “They go really well together” event (TGRWT #16) hosted by Supernova Condensate I decided to leave the chicken untouched and focus on the rose component. I had long wanted to try Chad’s Lemon whip (which I’ve included in Texture) where lemon juice is thickened with xanthan and then whipped to a thick foam after addition of methyl cellulose. I started with water, a little sugar and about 10 g of rose water. Having added xanthan and methyl cellulose I tasted it and decided to double the amount of rose water, add some more sugar and add a little lemon juice for acidity. I can imagine that rose water comes in differents strengths so it’s advisable not to add all from the start.

Rose foam
15 g sugar
0.7 g xanthan (0.49%)
100 g water
20 g rose water
8 g lemon juice
1.2 g methyl cellulose (0.84%)
(I used Metil from Texturas)

Grind sugar and xanthan. Sprinkle into water, rose water and lemon juice with hand mixer on full speed. When the xanthan is dispersed add methyl cellulose a little by little with the mixer still on. Mix for another 5-10 minutes until bubbles are small and uniform and the foam is dense and stable. If desired the foam can be whipped with an iSi whipper charged with nitrous oxide. I served the rose foam with diced apples, stalk celery and chopped almonds as a side dish to roasted chicken. Mashed potatoes with basil leaves, topped with a good olive oil and ground pepper was nice with the chicken.

Verdict: The rose foam is thick and lucious. The rose aroma blends very well with apple aroma. Lemon, almonds and celery give a nice contrast. The overall combo was a pleasant surprise! My previous encounters with rose water have been somewhat overpowering (especially in food from the Middle East), but the rose foam was much milder as I had diluted it with plenty of water.

The foam is stable on the time scale of minutes to hours. When left overnight the bubbles coalescese, but the volume of the foam remains more or less the same. Foam from the previous day can easily be whipped up again with a hand mixer.

Newly whipped rose foam (left), 18 hours later the bubbles have coalescesed (right). I apologize for the somewhat weird colors.

The next TGRWT challenge has been announced: chicken and rose! Head over to astrophysics blog Supernova Condensate and read more on how to participate in round 16. And do check out the excellent summary of the dark chocolate and smoked salmon contributions from TGRWT #15 over at Mex Mix.

The TGRWT #15 challenge was to pair smoked salmon with dark chocolate. I decided to encase a piece of hot-smoked salmon in a cocoa gel and serve it with sugared slices of lime. But as you can see from the pictures quite a lot went wrong… But it tasted quite nice!

Smoked salmon encased in agar cocoa gel
Agar gel:
400 g water
10 g cocoa
35 g sugar
2.5 g beef stock powder
10 g balsamico vinegar
35 g lime juice
1.8 g agar (0.37%)

smoked salmon
lime
sugar

Combine all ingredients for the gel and bring to boil. In a suitable (shallow) tray, pour one layer and leave to gel. Place salmon on top and pour more of the hot agar solution. Leave to gel and repeat until salmon is complete covered. When gelled, invert and slice carefully. Serve with thin slices of lime sprinkled with sugar.

Verdict: Even though I didn’t have time to finish the dish presentation-wise, I did of course taste the different components together. The lime added much needed freshness to the cocoa gel and combined well with the fish. The cocoa was not overpowering. The dish will work fine for a starter or as finger-food once I get the presentation right.

Lessons learnt

• For layered agar gel preparations it’s crucial that the next layer is poured while piping hot so that it can melt a little into the layer below. Because of agar’s significant hysteresis the gelled agar must be brought up to around 80-90 °C to melt.
• The box I used was way too deep (and the best at hand at the moment), but it might have worked if I had lined it with plastic wrapper. The layers came apart as I was trying to get it all out of the box. A higher agar concentration would make for a stronger gel, but it would also trap more flavor. Possibly it would also be more difficult to get the layers stick together at higher agar concentrations. Does anyone have experience with layers agar preparations?
• The hot-smoked salmon tastes very nice, but it’s texture was a litte to tough. I tried making slices, but both the salmon and the cocoa gel fell apart. This could be solved by switching to cold-smoked salmon. But a potential problem here might be that it will become “cooked” (and change color from translucent to opaque) once the hot agar solution is added. In that case one might have to revert to gelatin which melts at lower temperature.

This month’s round of “They go really well together” (TGRWT #15) is hosted by Mexmix and foods to pair this time are dark chocolate and smoked salmon. As usual you can find instructions on how to participate in the announcement post. Don’t forget to check out Rob’s summary of the malt and soy sauce round.