As a food lover there's nothing better then learning new techniques to improve my own cooking.
Over the years I have learnt from many people and am grateful to those that have been generous enough to share their knowledge with me. Some of these people I have had the privilege to know in person and others have just been a nickname and a posting on an internet forum.

I am a regular contributor to the Egullet.org food forum posting under the nickname of Origamicrane.
I have been a member and a society donor since 2004 and you will find me posting and asking questions in the Cooking, Baking, UK , China , Japan and Asia/Pacific forums.

I love experimenting with food and new dishes and over the last three years I have been reading and learning about Sous Vide cooking and molecular gastronomy. During the course of this gastronomic adventure I have started to study the science and chemistry behind the cooking.

Below is one of my most popular posts relating to my research in perfecting Chinese crispy roast pork crackling (Siu Yuk).

The Great Food Experiment 1 - Chinese Crispy Roast Pork

PART 1.

Hi all
after reading this thread and the pork belly thread in the cooking forum I decided to do a little experiment on how to get the best crackling.
So everyone agrees the main prerequisites are dry skin, good fat layer, scored/pierced skin, salt and lots of heat.
But after reading the two pork belly threads in the forum I learnt that sometimes the reason we don’t get good crackling is because we haven’t denatured the skin enough and the tough skin prevents the blistering and crackling from forming.

So we can denature the skin by scoring, piercing, heating and using chemcials to attack it.

So here I have two pieces of pork belly and I plan to divides these into 8 pieces and prep each one slightly differently to see which gives the best cracking results.

bellies

overview

so here's the fat layer on my pork bellies.


it’s a little hairy so used a blowtorch to just singe off the bristles .


then I scraped the skin with a sharp knife a few times to removes the burnt bristle ends


then I made 5mm score lines using a clean craft knife.

For sui yuk we have a spiked hammer tool/thing to pierce the skin
but for some reason I can’t find mine anywhere so I just settled for score lines instead.

I boiled 5 litres of water

put the pork bellies on a wire rack in the sink and slowly pour the boil water on to scald the skin. The skin contracts a lot when you do this.

lots of steam


I pat dry the skin with paper towels and then sprinkle 2 teaspoons of salt over the skin of each belly and rub it in.

I cut the flesh in 1 inch sections down to the first fat layer

rubbed in my marinade of
1t salt
½ t sugar
1t five spice powder
½ t white pepper
5 clove minced garlic
1 T meen see/miso
1T hoisin sauce (but I didn’t have any in the house today)

so far this is a pretty typical siu yook preparation.

Now I divide the pork bellies into 8 pieces for my 8 tests.


The 8 tests are

Test 1. make more score lines both horizontal and vertical, this will be my control piece.

Test 2. use a blow torch and lick the surface of the skin with the flame until I see the skin dry and change colour but I don’t burn or blister the skin.

Test 3. brush lemon juice on. As it is acidic it should denature the skin.

Test 4. brush vinegar another acid to denature the skin.

Test 5. brush lye water (kan sui) or 50% potassium carbonate in solution.
An alkali used to denature the skin and is the traditional Chinese method I believe.

Test 6. brush baking powder/ bicarbonate of soda – 50% sodium bicarbonate in solution.
Probably the most common alkali in a western kitchen and you are more likely to have this then lye water.

Test 7. brush alcohol – 40% vodka – dehydrates and denatures proteins, although I read that I actually need a 70-80% solution to really do the job.

Test 8. brush kiwi juice - contains a protein digesting enzyme called Actinidain and i use this to tenderise tough cuts of beef.

so here are the 8 piece on a platter

these go back into the fridge uncovered for 24 hours to dry some more. I will cook these tomorrow

stay tuned and fingers crossed I get some success.
oh and happy new year!!

PART 2.

ok! I just cooked my pork bellies.so took the bellies out of the fridge and then lightly sprinkled some more salt on the top.
I used a salt shaker and probably used less then a teaspoonful of salt on the 8 pieces.
Cooking times and temperatures:
put in middle rack of a preheat oven start with 20 minutes at 240C
then 20 minutes at 200C
then 10 minutes at 240C
followed by 5-10 minutes under the grill whilst carefully monitoring that crackling isn't burning.

Even before I finished cooking I could already see which ones were working and which weren't.
After the initial 20 minutes at 240C you could see that the lye, torched, soda and vodka was already blistering and the kiwi one looked like it was burning.

The results are as follow.
Here's a picture of all of the pieces after being in the fridge for 24 hours you can see which ones have dried more by the slightly dark skin tones the white ones are the ones that are still more wet.

here's what they looked like after cooking a little bit of burning but nothing a good knife scrap won't remove.

and here is a cross section off all of them together

TEST 1 - BLOW TORCHED SKIN

torched skin after 24 hours in the fridge

out of all the pieces this was pretty much the driest skin, touching it you could tell if was very dry and hard.

torched crackling

had a pretty even bubbling and colour

torched cross section

Verdict: very even colour and even crackling, good crunch with a little resistance.

TEST 2 - LEMON JUICE

lemon skin after 24 hours in the fridge

this looked dryish but the skin still had some suppleness.

lemon crackling

good crackling again not as even but good colour

lemon cross

Verdict: a harder crunch then the blow torched and slightly chewy.

TEST 3 - VINEGAR

vinegar skin after 24 hours in the fridge

similiar to the lemon skin but seemed wetter still.

vinegar crackling

pretty similiar to the lemon in colour and blistering

vinegar cross

Verdict: this crackling was lighter and had a softer crunch compared to the lemon crackling.

TEST 4 - KIWI

kiwi skin after 24 hours in the fridge

the skin was the wettest out of all of them

kiwi crackling

err..... picture says it all, it didn't form crackling but instead turned into burnt plastic skin.

kiwi cross

Verdict: complete failure i guess a protein digestive enzyme is no good for crackling, maybe it digested so much of the skin that there was nothing to blister? I know that if I use kiwi juice to tenderise meat for more then 6 hours it turns the meat into meat paste.

TEST 5 - VODKA

vodka skin after 24 hours in the fridge

this was surprising, as the skin seemed pretty dry

vodka crackling

very even crackling and colour whilst this was cooking i could see this was the one that was forming the most uniform crackling

vodka cross

Verdict: a very good crackling, light crunch, very even blistering and colouring.

TEST 6 - BAKING POWDER

baking powder skin after 24 hours in the fridge

skin was pretty dry and seemed hard, not very supple.

baking powder crackling

This looked like it was forming good crackling at the end of the designated cooking time but the middle still hadn't blister completely so I left it under the grill for a further 3 minutes. End result was not as even colour or blistering.

baking powder cross

Verdict: reasonably crunch but was noticably more chewy then the previous ones.

TEST 7 - LYE WATER

lye skin after 24 hours in the fridge

this skin was very dry and took on a hard waxy appearance

lye crackling

hehehe a picture says a thousand words? this was easily the best crackling in colour and blistering,
the crackling actually rose and seperated from the fat layer.
In fact this was already blistering in the initial 20 minutes of cooking.

lye cross

Verdict: easily the best looking crackling and crunchiest but also had a very slight chewiness.

TEST 8 - SCORED

scored skin after 24 hours in the fridge

this still looked pretty wet in comparison to the torched and alkaline brushed pieces.

scored crackling

this one had the best golden colour and even blistering but might have been due to the fact it was the middle piece. I scored this one a lot more in both horizontal and vertical directions.

scored cross

Verdict: this crackling was tougher and chewier then the rest although having said that it would still be acceptable to most people.

This was great fun :) and the winner of the best crackling was easily won by the Lye Water.
The baking powder did surprisingly well and next time i will use pure bicarbonate of soda rather then baking powder and see if i get an even better crackling.

So it looks like the chinese restaurants were right about lye water.
Lye water did produce the best crackling but it didn't produce the best siu yook in my opinion as siu yook should have the crackling still attached to the meat.

Surprisingly the best siu yook in my opinion was my wild card vodka as it had the best colour and crunch and most even blistering and still had the crackling attached to the meat. Think i will repeat this using a 60-80% alcohol solution next time and pit it against pure baking soda and lye water.

the worst one was the kiwi as it just started burning rather then blistering.

so my order of preference

1. vodka
2. lye
3. baking powder
4. torched
5. vinegar
6. lemon
7. scored
8. kiwi - not really counted as it completely failed

BTW just to clarify apart from the kiwi all the other 7 were really sucessful.
If I had to taste all 7 cracklings in a blind taste test, the lye and vodka would have been clear winners but for the remaining 5 it would have been very hard to distinguish between them.
So basically all the different methods do work very well but the lye and vodka do have the edge on lightness and crunchiness.

I will repeat this experiment again next month with the following changes
I will just use a spiked hammer to pierce the skin rather then score it
and i will do three tests

1. lye water
2. a 60-80% alcohol solution
3. a 50% bicarbonate of soda solution

and leave them for 2 days in the fridge.

If anyone has any observation or suggestions please let me know :)