Q&A: Science of the Kitchen

[eGCI Team]

Ask your questions about the Science of the Kitchen on this thread.

[jackal10]

Firstly let me thank my editors, organised and chased by Marlene, being Carolyn, Curlz and last but by no means least Andy Lynes for making it look as good as it does. The mistakes and inaccuracies are all mine.

The intention is that this will build into a book length course on Scientific Gastronomy. The current plan, which is still provisional and will no doubt change as it gets written is as follows

The course is divided into the following 12 sections:

I. INTRODUCTION

• Why cook?

• References

2. The effects of heat on muscle and protein

• The structure of muscle:

• Dry cooking: cooking a steak,

• Low temperature roasting

• Wet cooking: Dr Marigolds's Pudding

• Fish and Eggs

• Summary of Temperatures

3. The effects of heat on cabohydrates

• Introduction to a tangled web

• Simple and not so simple sugars

• Complex sugars and starches

• Hydro-colloids

- Gells

- Foams

• Natural sources

- Flours and gluten

• Digestion

4. The effects of heat on fat

• Butter

• Rendering lard

• Chocolate (and tempering)

5. Sources and transmission of heat

• Conduction of pans; frying

• Radiation: grilling

• Convection: boiling, baking, fan vs convection oven

• Microwave tricks, electric sausages

6. Browning

- Maillard reactions

• Caramel

7. Colour Magic

• Red: cabbage as indicator; tomatoes, fruits, meat, hemoglobin

• Orange: carotene

• Yellows: saffron, egg yolks,

• Green: Chlorophyll

• Blue: Blue potatoes, berries etc

• Violets: Flower colors

• Layered effects: Pousse Café

8. Basics of taste

- Salty, sweet, bitter, sour

- How little can you taste? (Successive dilutions)

- Umami

- Smell

9. Changing textures

Texture clues

- Emulsions and foams

• Ferran Adria’s way with water

• Mayo, vinaigrette, soufflé, "air"

• Bread and cakes

• Prawn crackers

10. Solids and liquids

Physics of phase change: controlling crystal growth

• Ice, water, steam:

• Sorbets, and ice creams,

• Jams and jellies: Pectin, gelatin, agar, starch gels, custards

• Making stock, tea and coffee: solution and concentration

11. Fermentation

• Bread

• Beer and Wine

• Yogurt and Cheese

12. Preservation

• Pickling and salting

• Drying

• Hygiene and cleanliness

The current article is the Introduction and most of Section 2.

When the rest will appear is variable, and depends how much time and inspiration I get to write, but it is probably a project lasting several years. Suggestions, feedback, corrections, different topics, people to help write welcome.

Edited April 9, 2004 by jackal10 (log)

[jackal10]

Here are some bits that got left out.

FISH

Fish muscle is a lot more delicate. The structure is different to meat, and has much shorter muscle strands, interspersed with thin sheets of collagen.

The secret of fish cooking is not to overcook. An internal temperature of 45C/100F will be found sufficient.

EGGS

Eggs cook by denaturing their proteins. They also benefit from long, low temperature cooking. The magic temperature for eggs is 60C/ 140F. Egg whites coagulate at about 60C/140 F while yolks are at 68C/155F.

Cooked for 12 hours at 60C/140F the egg is transformed into something magical. The yolk hardens and is no longer runny, but it is orange and wonderfully "creamy." The white coagulates but is still very soft, like a solid custard--perfect for one of the sauces in The Big Egg List.

Long cooked hard boiled eggs, coloured with onion skins or coffee, “Beid Hamine” were a traditional Sephardic food. Hamine is one of the versions of the overnight cooked Sabbath food, in which the eggs were originally cooked.

Chinese spices work well

LONG COOKED MARBLED TEA EGGS

Crack the raw eggs all over but do not break open.

Make up the following tea mixture:

1 Tbs light Soy

1 Tbs dark soy

¼ tsp salt

2 whole star anise

2 Tbs black tea

2 inch length cinnamon stick

Small piece of dried orange or tangerine peel

3 cups water.

Put in the eggs and bring to the boil. Cook at 60C/140F for 12 hours, ensuring the eggs are covered, topping up the pot with water if required. Peel to reveal the marbling.

Look good if served on fried “seaweed”

MASTER SAUCE EGGS

Similar but different origin and without the marbling.

A master sauce is made up in a casserole, and many things are cooked in it, exchanging flavours with the sauce, which gets better all the time.

Basic Master Sauce:

2 ½ cups water

2 cups light soy

1/3 cup rice wine or sherry

4-5 slices ginger

12 points of star anise

2 oz/50g golden sugar

Optional:

1 scallion chopped

1 tbs cinnamon bark piece

1 thumb size strip of orange or tangerine rind

Bring to the boil. Put in the food (eggs in their shell, but the same method can be applied to meats, poultry, seafood etc) and cook at 60C/140F for 12 hours.

Take out, peel and quarter the eggs to show off the colouring.

Filter the sauce, and keep for next time.

Heston Blumenthal, in this article in the Guardian, one of his excellent series there, quotes work at the University of Reading to show that 12 minutes at 60C/140F kills e.coli and most common bacteria. It is however temperature sensitive: it takes 45 minutes at 58C/135F.

This implies it as actually safer to cook for longer at lower temperature, as the centre of the meat is more likely to reach and hold at the required temperature than the normal blast in a hot oven, grill or frying pan, which, as we have seen, leaves the inside of the meat comparatively cool and potentially still contaminated.

Cooking grain proteins, like gluten, will be in a future unit, I hope.

Edited April 9, 2004 by jackal10 (log)

[rubyred]

Hi Professor Jack!

First, I'd like to thank you for starting this series. As a food science neophyte, there is a lot of information out there to read. Your succinct chapters written in plain language will provide me (and so many others) with a solid framework for further study.

I also have a question: Your chapter on meat focused primarily on beef; do the principles you discussed regarding the structure of meat apply to all types of meat, such as poultry?

[jackal10]

Yes, they apply to all meats.

In particular for poultry long slow cooking at 60c/140F allows the legs and thighs to cook, without overcooking the breast meat.

Fish, as I say above, has a lower transition temeprature, more like 45C/110F

[balex]

Great course! One comment -- you say a joule raises one cc (or 1 g) of water by one degree. This is the old definition of a calorie -- which is actually about 4.2 joules. (and a food calorie is 1000 of these calories)

What sort of thermometer do you recommend? I have a crappy digital meat themometer with misleading temperatures on the side and I am in the market for a good one. Are there any that are oven safe so you can leave them in the whole time? If the oven is at 60 degrees then this is not a problem I guess.

What about wireless ones?

[jackal10]

You are right! One watt is a joule per second.

I use an electronic thermometer with a cable that goes through the oven door. I bought it originally from http://www.meilleurduchef.com/, but I see Amazon sell them from Pyrex, CDN and other makers. The wire that goes through the door is the key thing, and the single thing that improved my cooking the most.

I prefer ones that just measure, rather than being too clever, though I can see that remote wireless displays/pager might be useful. However I guess these would be on the same band as my wireless phones, wifi etc - its getting crowded there.

[jsolomon]

Andy,

Great eGCI course! I am really impressed by how you were able to pare information on cooking meats down to a manageable level.

I have a question of high temperature vs. low temperature cooking. Your course dwells almost exclusively on the side of sear then cook slow, or cook slow then sear. However, I contend that there are many dishes (roasted cut-up chicken, for instance) that can handle something on the order of 500F ~275C for 40-50 minutes, depending on bird size.

Splitting hairs-wise, I understand that I am essentially taking advantage of 1) the size of the piece and 2) the thermal conductivity of meat, to allow me to reach a "sweet spot". This version of cooking always ends up crispy and delicious on the outside, and fork- tender on the inside.

My question is: does kinetic (high heat, shorter time) cooking have as widespread a calling as equilibrium (~target temperature for longer time) in molecular gastronomy? I realize that you have touched on it a bit with the browning you advocated, but I have run across several people's sites that seem to ignore a sear/kinetic cooking.

For cooking reference, Barbara Kafka's book titled Roasting is where I really ran across the kinetic version of roasting as opposed to equilibrium that you advocate.

Edit to fix broken link... I hope I linked through eGullet to Amazon correctly.

Edited April 11, 2004 by jsolomon (log)

[gus_tatory]

Jackal10--

brilliant as usual--thanks!

two questions:

--i'd like to try the 7-hour roast beef, but my oven settings go straight from "warm" to 200. would you advise the warm setting, or the 200 deg f setting for less time?

--where on earth did you find MRI images of meatballs?!

thanks again...

[jackal10]

Jsolomon:

Its all about eventual temperature. If the kinetic method works for you stay with it.

However the long slow roasting is easier to control, and results in a tenderer results since some of the collagen has time to soften.

Blumenthal goes further and cooks his meat sous-vide for 72 hours at 60C for a fork tender result.

[jackal10]

gus_tatory:

Buy a thermometer!

I expect you will find that the "warm" temperature is about 60C/140F, but measure it to check. Unfortunately most ovens are not designed for the very long slow cooking - yet.

It does seem strange at first - cooking the meat by just warming it, but have courage.

The meatball photos's came from Prof. Hall, a fellow member of my college, and Director of the Herchel Smith Laboratory of Medicinal Chemistry, University of Cambridge. http://www.hslmc.cam.ac.uk/index_hires.htm. Scroll down for the section on Food Science. They are pioneers of MRI, have developed techniques to measure temperature and pH (acidity) and have even built ovens that can work inside a scanner and got wonderful movies of bread baking, and all sorts of other food processes. Wonderful stuff.

[jsolomon]

Andy,

Great eGCI course!

Jackal10, I have to apologize for not properly thanking you, and instead thanking Andy. I'm occasionally stupider than toast.

So, Great eGCI course, jackal10!

[Abra]

Excellent course, and I look forward to the upcoming installments! Is there any chance that you'd create a table for us, with type of meat, weight, and aooroximate time to reach temp using the 140 degree method? I'm longing to try it, and do have a thermometer, but it'd be wonderful to know in advance how long various pieces of meat might take to get up to temp.

[ExtraMSG]

Good stuff. I've been arguing your case on the juiciness issue for a long time and its nice to have solid backup. It's an article I wish I'd written.

However, I do have a couple questions. I hope they weren't covered since I'm out of town and don't have as much time to read carefully:

1) In the slow cooking method, how well does the skin on poultry crisp? I imagine it renders quite nicely, but does it crisp nicely beyond whatever you do in a pan (poultry is not the easiest thing to crisp in a pan)?

2) My method for poaching chicken has become starting the meat in cold water and bringing it to about 170, then turning it down until the meat reaches 180. I've found that I get excellent flavor penetration this way. Onion, peppercorns, vanilla, whatever I put in the poaching liquid seems to flavor the meat really well. Can you explain this? Is it just the longer period of time the meat stays in the flavored liquid?

3) Could you post some larger photos of the meat matrix?

[jackal10]

Excellent course, and I look forward to the upcoming installments!  Is there any chance that you'd create a table for us, with type of meat, weight, and aooroximate time to reach temp using the 140 degree method?  I'm longing to try it, and do have a thermometer, but it'd be wonderful to know in advance how long various pieces of meat might take to get up to temp.

Each piece of meat is different, and the temoerature in the centre depends on the thickness.

The whole point about the low temperature method is that if the oven is at the temperature of the final temperature you want the meat, it doesn't matter how long you leave it after the temperature stabilises - say 5 hours of so. Blumenthal cooks his meat (sous-vide to prevent frying) for 72 hours at 60C to melting tenderness

However you can read off typical times from the graph in the unit.

Use with cautions,as these are theoretical models, not measured in practice.

There is no substitute for a good themometer

Here is the same information in tabular format. The column on the left is the time in minutes

    Oven temperature    	
    C   F    C    F    C    
   65	150	100	212	200	400
      
0    0  32  0   32  0  32
10   5  41  8  46  15  60
20  10  49 15  59  30  86
30  14  57 21  71  43 109
40  18  64 28  82  55 131
50  22  71 33  92  66 151
60  25  77 38 101  77 170
70  28  82 43 110  86 187
80  31  88 48 118  95 203
90  34  92 52 125	103	218
100 36  97 55	132	111	231
120	40	105	62	144	124	255
130	42	108	65	149	130	266
140	44	111	68	154	135	276
150	46	114	70	158	140	285
160	47	117	72	162	145	293
170	48	119	75	166	149	301
180	50	122	77	170	153	308
190	51	124	78	173	157	314
200	52	126	80	176	160	320
210	53	127	82	179	163	326
220	54	129	83	181	166	331
230	55	131	84	184	169	336
240	56	132	86	186	171	340
250	56	133	87	188	173	344
260	57	135	88	190	175	348
270	58	136	89	192	177	351
280	58	137	90	193	179	354
290	59	138	90	195	181	357

Edited April 13, 2004 by jackal10 (log)

[jackal10]

1) In the slow cooking method, how well does the skin on poultry crisp?  I imagine it renders quite nicely, but does it crisp nicely beyond whatever you do in a pan (poultry is not the easiest thing to crisp in a pan)?

2) My method for poaching chicken has become starting the meat in cold water and bringing it to about 170, then turning it down until the meat reaches 180.  I've found that I get excellent flavor penetration this way.  Onion, peppercorns, vanilla, whatever I put in the poaching liquid seems to flavor the meat really well.  Can you explain this?  Is it just the longer period of time the meat stays in the flavored liquid?

3) Could you post some larger photos of the meat matrix?

If you flash the poultry in a very hot oven after its cooked you will get very crispy skin. - rather like air-drying Chinese duck before cooking.

Of course you can enhance this even further by laquering the skin with dilute honey or syrup. For extra browning add a little alkali, such as bicarb. However only use alkali after it is cooked (acid conditions inhibit nasties like botulism, and you need to kill them first).

I don't know but I would agree that the extra time in the flavoured liquid will increas the flavour. Have you tried of marinating instead? Also 180C seems a little high - you might get a more succulent product at 140C, held there for at least 12 mins.

Edited to add eGullet does not permit pictures bigger than 640x480.

If you need them bigger email me.

Edited April 13, 2004 by jackal10 (log)

[Abra]

I do understand about the thermometer. I hesitate to say this lest it seem like criticism (which it isn't) but outside the laboratory, menu planning dictates that one be able to predict doneness and serving time, which is why I was wondering. Not how to determine when the food is done, but how to have the rest of the meal and the diners ready when the meat it.

[jackal10]

Ahh, but that is beauty of slow cooking, that the time element is far less important.

It takes the hassle out of a busy kitchen, and is ideal for restaurants.

You can set the meat to cook in the morning for dinner, and forget about it. Whenever you want it for service, its ready. If the guests are an hour late or an hour early it doesn't matter. Doneness is enitirely dependant on the temperature you set the oven, not how long it cooked. No settling time, either. Just take it out and carve...

[Jinmyo]

Jack! Egad! This is great!

[MobyP]

Jack - this is phenomenal. I cooked the lamb, and it was the most tender lamb anyone had ever tried. You mentioned the book - are there any plans to release additional sections on eGCI, or are you vying to be the next Nigella? And just how many soft sweaters do you own?

[jackal10]

Jack - this is phenomenal. I cooked the lamb, and it was the most tender lamb anyone had ever tried. You mentioned the book - are there any plans to release additional sections on eGCI, or are you vying to be the next Nigella? And just how many soft sweaters do you own?

I'd expect to release the sections on egCI as they get written.

It would be great if other people join in the project - JAZ has a great unit on taste in the works.

No one has comissioned a book yet, although I believe FG has something for the whole of egCI planned - there is lots of good material there. I'd hope some publisher might take it up, or other publishing routes like articles or TV. However, this is for fun, rather than income,,,

I have about 20 soft sweaters, but some are fit only for gardening. Why? I don't follow the reference...I could never compete with Nigella - I don't have the figure for it.

Edited April 14, 2004 by jackal10 (log)

[gsquared]

Great material, Jack! Congratulations. I am interested in the application of slow cooking to fish, especially as it is so easy to overcook fish. Please consider covering this in a future unit.

[jackal10]

Fish was originally in this unit, but got edited out.

Fish proteins are more delicate than meat proteins, so the decomposition tenperature is lower - only about 45C/110F.

Most ovens don't go that low, so it can be a problem. Its about the temperature of hot water tap water. For short periods double wrapping the fish in foil, or putting it in a heavy casserole delays the heat transfer for hour or so, but not for very long periods

Its one of the reasons why fish cooked in batter is so moist and delicious - the thick batter coating protects the fish from the hot oil.

Sous-vide, or steaming, or warm smoke, with quite a lot of space between the fish and the heat source, such as an empty steamer basket or two below the the basket with the fish in it, works, as does very gentle poaching or frying.

More solid fish, such as tuna doesn't conduct heat that well, so the "blackened" style, where the outside is seared briefly, but the inside is still comparatively raw also work.

My favourite summer method is to put a thick layer of green herbs directly on the BBQ and the fish, such a a whole salmon on that, turning after 10 mins or so with fresh herbs. It smokes/steams. The herbs char and stick to the skin of the fish, but since you peel that off it doesn't matter.

As with meat, a good remote reading digital thermometer will take out the guesswork.

[Dan Ryan]

Jack, I take it you're familiar with Peter Barham's The Science of Cooking (great book btw). He suggests using a blowtorch to cook whole fish as it browns the outside very quickly. Really enjoying the course so far. More to come?

[jackal10]

Jack, I take it you're familiar with Peter Barham's The Science of Cooking (great book btw). He suggests using a blowtorch to cook whole fish as it browns the outside very quickly. Really enjoying the course so far. More to come?

Yes, I have the book. I do prefer McGee's book.

Depends if you are eating the skin or not.

I find cooking a fish with a blowtorch (or very hot grill) hard to control.

Even then you need to let the fish stand so the heat evens out.

Its a different dish from the long-slow cooked low temperature one

Lots more to come. I'm in the middle of writing the carbohydrate unit...a long tangled and sticky tale.

Are people put off by the science stuff? I'd like to include some chemical formulas in the next unit.

Edited April 15, 2004 by jackal10 (log)