Thursday, 30 January 2014

Building a wood fired bread and pizza oven - Pizza Time

Exciting day today in the storey of building our wood fired bread and pizza oven.  The first hurdle was to make a safe exit for the exhaust gases from the bakery.  This required a double walled insulated stove pipe with a flashing to stop the rain and snow coming in.  None of this was available so we fabricated our own.  

Using two different diameters of stove pipe made from 2 mm mild steel, 160mm and 200mm diameters, the inner pipe is wrapped in high temperature, foil faced mineral wool.  We bound the mineral tight to the inner pipe by wrapping it in thin mettle wire and with a bit of teasing the 200 mm pipe squeezed over.  The outer pipe has the flashing welded to it at the correct angle for the ridge of the bakery roof.  The flashing we cut out of 2 mm steel sheet.  The whole thing was then cleaned up with a wire brush attachment on the angle grinder and painted, first with rust resistant primer and then a black finish coat.

Today we also took delivery of the Perlite that we will be using as a loose fill insulation around the oven.  As the delivery charge was initially more than the cost of the perlite, I decided to get a whole pallet, about 1500 L, about a hundred pounds.  More than we need, but maybe I will start growing plants in this stuff in the spring.

A little perlite insulation

With the flashing painted we could then complete the remainder of the work on the chimney.  The path the chimney takes was done so that the minimum distance between any hot surface and and flammable material is 450 mm.

Finished chimney

With the chimney completed and my parents arriving today ready for our daughters 1st birthday party on Sunday, I could not resist the temptation of have a practice run.  As mentioned in a earlier blog post, a couple of weeks ago, I promised that that oven would be ready in time to cook pizza for the party guests. At times I thought we would not get everything ready, but by getting help from Damian, we are just about ready. Last minute fabrication of a peel, handle of rough cut wood, smoothed to remove and splinters with an orbital sander.

making a peel

2 mm steel paddle cut out with an angle grinder.  Stainless would have been better, but I don't have any laying around.  Cleaned up with the wire attachment and then treated with vegetable oil and heat.

cutting out the blade of the peel

This is my first time making pizza, but I know the basics.  Really hot oven with the embers still sitting around the edge of the oven.  I made a simple dough similar to my focaccia recipe here, but not as wet and as I had not time to mess around, instant yeast was used instead of sourdough.  

After firing the oven for a couple of hours the embers were pushed to the sides and the hearth, mopped with a wet cloth wrapped around a garden rake.  The temperature of the hearth at this point was around 500 °C.

Mopping the hearth to remove some soot

measuring temperature of the hearth

A tomato sauce I have used is half good quality tinned tomato half passata.  Lots of garlic black pepper and a glug of balsamic vinegar, simmered for a while to intensify the sauce.  The first pizza was topped with home made air cured pork belly, onion and spinach.
Spinach and air cured pork belly

The second pizza was topped with home made chorizo, onion and black pepper.

Home made air cured chorizo

Had lots of fun finally using the oven that has taken so much planning and time to build.  Next step is to bake bread on Saturday followed by a very large number of pizzas on Sunday.

Tuesday, 28 January 2014

Building a wood fired bread and pizza oven - Chimney transition and more fire

Last few days have mainly been concerned with making the chimney transition, this part will act to smoothly transfer the exhaust gases to the round chimney pipe and will also contain a flap that can be moved to adjust the flow rate.  Fully closed the chimney damper will enable to oven to be sealed during baking of bread.

The transition section has been made from 2mm sheet steel, cut using an angle grinder and then welded using a cheap stick welder. The shapes were worked out by first drawing it in Sketchup and then transferring the measurements to the sheet steel.

Chimney transition in place
With the chimney transition in place, the curing fires are a lot easier to light, keep it burning and a cleaner burn with less smoke.

The oven dome has also been covered with some temporary insulation, the insulation is a foil faced mineral wool that is rated to 530°C.  I have covered the dome in this as it enables a more even heating of the dome during the curing process.

The curing fires have gradually been increased in temperature, the oven has now been fired for a total of about 24 hours.  Unintentionally, the curing has now been completed, after (I thought anyway!) fire had gone out last night, I completely filled the oven with alder logs.  I had planned to leave the logs in the oven as they had been in the rain, leaving them not dry enough to fire the oven.  Unfortunately there must have been some embers left in the oven and once the logs had dried out they ignited.  When I woke up this morning there was a large hole in the roof of the bakery (fortunately, it did not set fir to the structure) and there was a very small amount of ash where the logs had been.  The fire must have been seriously hot, all the black soot that had collected inside the oven was burned off, even on the reducer dome and chimney transition.  Several hours later the temperature of the brickwork is still over 300°C and the temperature of the hearth insulation transition is at 230°C.  I had intended to spend a few more days gradually increasing the temperature, but I guess the curing process was expedited.  There has been some cracking near the centre of the oven, but nothing more than I had expected even with a proper curing process, some in the brick dome and one crack in the refractory slab that the hearth sits on.

Friday, 24 January 2014

Building a wood fired bread and pizza oven - First curing fire

In the last couple of days we have made significant progress on my our wood fired bread and pizza oven. The final bit of cast refractory needed to be finished as early as possible as it needs at least 24 hours to dry out at 20 – 30°C before it can be cured at higher temperatures. This last bit of cast refractory covers the reducer arch and brings it up to the height of the door lintel. On the centre of these two components will sit the chimney.

pointing the inside of the oven

After all the vibrating of the cast, refractory is completed. We are confident that the reducer arch temporary supports can be removed. This then allowed just enough space for me to squeeze in and do a little pointing and cleaning up any unwanted mortar.

The main bits of brickwork have been heated for a few days now with an electric heater. The temperature has been gradually increased until for the last 24 hours the brickwork was held at around 40°C. The small amount of mortar used for pointing quickly dried out and so this evening I decided it was time for the first curing fire. The first curing fire was started, very small initially and then increased in size until a reasonable amount of embers built up.

For the first hour the inner surface temperature was kept to less then 120°C, this was at the point directly above the fire, then in the following 3 hours the temperature was gradually increased until most of the inside of the top part of the dome was at around 160°C. The highest surface temperatures reached were directly above the flames and were no higher than 220°C. At the front of the oven, around the chimney transition, where the refractory was only cast 24 hours earlier, the temperature did not exceed 90°C. This is in line with the curing protocol provided by PCO the manufacturer. The final temperature reached on the outside of the dome brickwork was 80°C. This was my target temperature for the day as it is the maximum surface temperature for the extruded polystyrene that is currently cladding the outside of the oven.

Monitoring internal surface temperatures using an infra-red thermometer 

Buried in the hearth of the oven at the hearth / insulation transition is a thermocouple. The temperature reached at this point, after 4 hours of gently firing was 46°C. I expect this continued to rise for some time after I wrapped up the oven and stopped monitoring in order to come inside and write up this post. It is -10°C outside at the moment, so I am glad to be finished for the night and inside drinking a hot coco.

Thursday, 23 January 2014

Rough Puff - perfect pastry for sausage meat snacks

Rough puff pastry sausage rolls

So, in less than a couple of weeks our daughter Dorothy is one year old and we are expecting about 20 relatives over for an afternoon party.  I thought I would get ahead and do some baking of some snacks that can be frozen had re-heated on the day.  One of my favourites is the sausage roll, not the kind you buy frozen, but home made they can be really delicious.  In this post I show you how I make a really simple but lovely rough puff pastry which is perfect for both savoury and sweet pastry dishes.

Rough Puff Pastry

This process is really easy to get right, just use a good quality butter and don't overwork and it will turn out great.  I am producing a big batch, so here are the quantities  I used;

750 g of plain flour
500g of butter, cold from the fridge
two pinches of salt
400 ml of water

 Cut the cold butter into cubes and put in a heavy, cold mixing bowl with the flour.  It is best not to do this in a very warm room, but if you have to, don't hang around, work quickly.

Break up the butter into ever smaller pieces.  I am using a special pastry tool, but I have also done it by holding two dinner knives.  Every time you cut the butter the cut edge gets covered in flour and so stays separated from the other bits of butter.

Stop cutting the butter when most of the butter is like breadcrumbs, but a proportion is left in pea size lumps. When we roll out the pastry, these lumps will be dispersed throughout and flattened into little leaves separating the pastry in to local layers.  This is where the puff and flakiness will come from.

About almost all of the water (cold) is added to a well in the centre of the mix.  Gently work the flour from outside with a spoon or knife, incorporating the water with as little work as possible.  The mix should be wet enough so that it binds together, without it being more than a little bit sticky.

With hands, gently press the pastry into a ball, don't start kneading like bread, we do not want to develop the gluten.

Put the pastry in a plastic bag and put in the refrigerator for 30 mins or more. 
At this point I have divided the pastry into two as my board is only big enough to roll out this much at one time.  Press the pastry into an approximate rectangle, again, without working too much.  The rectangle should be about the width that I will need to making my sausage rolls.   

Roll in one direction only until you have a long thin rectangle.  Fold like a letter into three and then rotate 90 degrees and then repeat the roll and fold process.

Put the pastry back into the refrigerator covered in plastic.  After about 30 minutes it will be ready to use.

The sausage meat 

For the filling I have chosen a piece of neck, but any part of the pig that has done a bit of work, leg, shoulder, etc. will make a very tasty filling. This is cut into cubes small enough to go through the mincer.  I have also included some extra back fat that I had in the freezer as I like my filling to be not too lean.

I have also added about 200 g of my home made air dried belly.  You could use a good quality cured bacon.  

I am lightly spicing my pork with black pepper, star anise and cinnamon.  This going to give and amazing smell and depth to the filling. 

I have also added two onions finely chopped, an unreasonably large quantity of garlic and about 100 g of bread crumbs.  The breadcrumbs are going to hold onto some of the fat that melts during cooking improving the moistness and flavour of the sausage roll.

The pastry is removed from the fridge and rolled out until about 5 mm thick.  If you don't have a board 1.3 m long you may have to do this in a few shorter pieces.  The meat is then pressed into a sausage shape on the rolled out pastry.

The pastry is sealed by brushing the seam with egg wash, I use equal parts egg and milk, and then I  pressed the folded over pastry together with the blunt edge of a pastry scraper. 

After cutting into the desired portion sizes, (the two large ones are for dinner tonight) they are baked at 180°C until a nice colour.

These are best eaten while still hot, but they also freeze and re-heat in the oven really well.  I'm not sure they are going to make it all the way to the birthday party.

Wednesday, 22 January 2014

Building a wood fired bread and pizza oven - finishing the brickwork

Now most of the brickwork is finished for the wood fired bread oven.  The main dome has been closed off by completing the end wall and the reducer arch has been finished and the large gaps between bricks backfilled.  The form-work has yet to come off the reducer arch, the oven will be covered in insulation for a couple of days with an electric heater inside to dry out the mortar first.  I have not had time to take as many pictures as I would have liked of the process I followed, but here are a couple of the end results.

reducer arch still supported
The back edge of the reducer arch has been shaped to allow better flow of exhaust gasses leaving the oven.  I will get a picture of this once the supports have come out.  The electric heater can be seen inside the oven.  It is around -6° C but with the oven well covered with extruded polystyrene sheets and the heater on, the internal temperature of the oven is about 35°C and the outside of the brickwork is feels warm when touched.

Rear wall of oven completed
After a couple of days of heating I expect the mortar to be fully dried out and then the temperature of the oven can be increased by lighting very small fires inside.  Before that can be done a small amount of cast refractory needs to be laid over the reducer arch to increase the thickness of the oven wall at the junction of the main arch and reducer arch.

Tuesday, 21 January 2014

Building a wood fired bread oven - Completing the main dome

This evening the main dome of our wood fired bread oven was completed.  We have been racing against the cold weather that has been forecast and unfortunately it has come a day early.  It looks like we could have temperatures below -5°C for the next month or longer.  In these temperatures the water content of the mortar will freeze which would not be good for the brickwork. In order to be able to continue in these temperatures, the dome needs to be finished and am electric heater sealed inside, this will keep the brickwork above freezing, and hopefully warm enough for the mortar to harden. 

I have been working flat out in the evenings in attempt to finish the main dome.

Main dome completed
You can see here the completed main dome.  The larger gaps in brickwork have been filled with a mix based on the the refractory mortar with a courser aggregate added.  This makes it more suitable for filling larger gaps and will help it dry out.  

I would have liked to leave the form-work for a couple of days, but a heater is needed under the arch, so the supports had to come out.  Fortunately the form-work came out without bringing all the brickwork down leaving the first glimpse of what the inside of the oven will look like.

Inside the oven arch
A little more brickwork still needs finishing before the oven can be wrapped up in insulation, so I am still working flat out.  I will update with further progress once I can take some more pictures.

Building a wood fired oven - dome bricks started

The first few dome bricks for our wood fired bread and pizza oven have now been set.  It is more usual for this to be done using a form for a single brick width so that.  The single brick width dome technique as described by Alan Scott in the book the Bread Builders, which I discussed in a blog post here, involves moving the form work after each brick arch has been set.  I have decided to make a full length form-work so that each course of dome bricks can be offset by half a brick for improved strength and resistance to cracking, it also allows me to build the entire dome before removing the support without worrying about it collapsing.  As I am racing the cold weather that is coming in a couple of days, and due to the lot temperatures here, the mortar is going off very slowly, so I need the dome finished fast and supported until it is fully finished.  

Form-work positioned in the oven
The form-work is adjusted to the correct height using four stacks of bricks and two quick substantial pieces of wood, cut the the correct length of the form.  The form has been trimmed to be just small enough to be removed through the oven mouth.

Angled dome support bricks
The bricks at the top of the side wall have been angled to maximise contact with the first dome brick.

First 4 rows of dome bricks
When laying the first 4 rows of dome bricks, some of the bricks did not want to stay in the correct position, so small pieces of fire brick have been wedged in the tapered gap between dome bricks.  Only a small amount of refractory mortar has been used here,  where the tapered gap become wider than about 6 mm, it has been left unfilled.  This will later be backfilled with a different mix of mortar.

Dome bricks supported by form-work
Care has to be taken in order to make the corners of dome bricks meet as closely as possible.  The bricks should fit together with almost no mortar separating them.  This is not possible in reality  due to slight inconsistencies in brick shapes and sizes.  
The weather here is looking like getting very cold in a couple of days time, so I need to get this dome finished, the supports removed and a heater under the dome before I get problems of the mortar freezing and destroying all our hard work.

Saturday, 18 January 2014

Building a wood fired oven - dome form

Today I was doing the preparation work that is needed before I can start to lay the bricks of the dome of the wood fired bread oven.  I have already cut and set the angles bricks that will brace the ends of the dome.  These bricks were cut using a large angle grinder with a diamond abrasive disk.  These bricks transfer the load of the dome to the steel strapping on the outside of the oven.

Dome support bricks ready for pointing and cleaning

In order to create the dome I need a parabola shaped form that will support the bricks until the mortar goes off.  The shape was drawn on a piece of paper to use as a template and then transferred onto a sheet of plywood.  I then cut out the shape a little oversized on the band-saw and then finish on the sander.  Once I am happy with the shape it is used as a template to 3 more sheets of ply, this time screwed together so I can make 3 with one pass.

Cutting out the form supports
 The 4 supports are then screwed to a sheet of plywood on their flat edge.  For the curved surface, as it will need to be quite strong, another sheet of 12mm ply will be bent over the supports.  In-order to make the ply flexible enough, cuts are made 2/3 of the way through the plywood using a circular saw.  I have made these cuts every 2 cm.  If you require a tighter curvature then the cuts will have to be closer together.

Making ply flexible for the form-work

The flexible sheet of ply-wood is then bent and screwed to the supports.  This is best done working from the centre out.  To ensure a strong form, a bead of polyurethane  wood glue is first applied to the supports. Screws will need to be more frequent the tighter the curvature required.

Finished dome form
With the form-work finished I am ready to the start the exciting bit, laying the dome bricks.

Wednesday, 15 January 2014

Stewed lamb shanks with potato gnocchi

Early afternoon, while planning what to eat for dinner last night, I had a quick look in the freezer and spotted two lamb shanks I have from the lambs that we raised this year.  How these were butchered I covered in an article here, It's time for the lambs.  Lamb shanks are not expensive and due the work the lower leg muscles do and the amount of connective tissue, when cooked right they make the most amazing stew with masses of flavour with super soft gelatinous meat.

This dish could be cooked in the oven in a heavy gauge pan, but this time I am doing this on the hob in a deep pan.

The trick to making this a really special dish is what you put in the sauce.  The flavour is going to come from the selection of vegetables. This time I finely chop onion and soften in some olive oil then add the lamb to the pot.  Next, a few handfuls of diced vegetables are added. This time I have used carrots, celeriac and parsnips. A few porcini mushrooms, a bunch of dried thyme and a tablespoon of balsamic vinegar. Then enough water just to cover the meat is also added.  Season with salt and pepper.

The stew is then put on a very low simmer.  I like to use a sheet of foil over the pan with the lid on top in order to make a very tight seal. The slower this is cooked the softer the meat will be. I then leave this simmering all afternoon until about an hour before we want to eat. The sauce is then separated from the meat and vegetables in order to thicken the sauce by boiling off much of the water.  I do not do this with the meat in as it does not require further cooking.  During the reduction process I add a little extra lamb stock to make the sauce even richer.  While the sauce is slowly reducing I prepare some potato gnocci.

Potato Gnocchi

Bake in the oven, in their skins, enough potato for the number of people you are feeding.  For two people I bake about 500g of potatoes. As the potato is being roasted the quantity shrinks due to moisture loss, but this is desirable as the lower moisture content of the cooked potato is going to make much better, more intensely flavoured gnocchi.  Once soft, remove the skins and press the potatoes through a potato ricer. Dust the riced potato in a little flour and season with salt and pepper.  As the potato has been riced the flour and seasoning can me mixed through without working the potato. I would always use a ricer for this, other methods of mashing the potato will overwork it and the gnocchi will be rubbery.  Once mixed, transfer the potato to a lightly floured surface gently press into a ball  and then roll out into a sausage shape about 2 cm diameter.  I then cut into disks and press a small indentation into once side with a finger.

The gnocchi are gently transferred into boiling water, once they start to float I give them another 30 seconds and they are done.  I strain the gnocchi and allow to stand for a couple of minutes while I melt some butter in a frying pan, then toss the gnocchi in the butter until they colour a little.

I then served the lamb on top of all the stewed veg with the gnocchi on the side and the thickened gravy poured over the top. This is a super meal that costs very little and is really simple to prepare without taking much of your time.  Its just a real shame that a lamb only has four shanks.

Saturday, 11 January 2014

New Experiment - Brioche Dough

Brioche dough is something that I have never tried baking, and I don't think I have ever eaten a proper bit of brioche.  As I did with my focaccia experiment, I will not be following a recipe from anyone else.  I like to follow a process with all my recipes and this brioche post is an outline of the process I follow.

Brioche bun with wild plum jam

First I have done a little reading about brioche, I found some interesting recipes, this one from Michel Roux is interesting and wikipedia's entry has a lot of historical context.  There seems to be a range of dough that could be considered brioche, most are bread dough fortified with eggs and butter. They range from the lightly fortified, but still more fortified than my sweet bun dough, with only a small amount of egg and butter, to heavily fortified. The Roux recipe is right at the rich end of the scale. 6 eggs and 350g of butter for 500g of flour is a lot of enrichment.  I don't really know how much fat you can put in a dough before the yeast retards so much that it will no longer ferment, but this is about as rich a dough as I have come across.

For my dough I want to put enough enrichment into it to produce a rich brioche, but I would also like to have a longer slower fermentation do develop some extra flavour.  In order to do this I will be using slightly less butter and I will be pre-fermenting a third of the flour with about 5g of instant yeast. Pre-fermenting will allow the yeast to multiply and by-products of fermentation to be produced rapidly without the presence of fat.

The pre-ferment is then thinned by adding 50ml of cold milk, the remainder of the flour added along with the eggs, well beaten first.  The dough is roughly mixed and then left to stand for 15 minutes, this will reduce the amount of kneading required.  I would make my dough as wet as possible in order to get the lightness and extended texture inside that I want.  This poses one of the problems I will face today as a really wet dough is quite easy to make with a mixer, but I do not have one, so this will need to be mixed enough to develop the gluten by hand.

After standing, 200g of softened butter is mixed into the dough, mixing for another 10 minutes brings the dough to a consistency that I am almost happy with, by this time, my arms are burning and ready to give up on the mixing.  Further development of the gluten is achieved by gently stretching and folding the dough a few times every 30 min during fermentation.  Fermentation is given 3 hours at about 20°C and then the dough is retarded in the refrigerator for 5 hours.  After laying a few bricks for my new wood fired oven the dough is taken out of the refrigerator and warmed up again for 30 mins before shaping.  I do not have any proper brioche bun tins or loaf tin, so instead I use large muffin cups and a regular loaf tin.  Each tin gets 3/4 of a portion of dough shaped into a ball in the bottom and then on top a smaller ball with the remainder of the portion.

Finally, I prove the dough for about 2 hours at room temperature until it is a little over 2x bigger than the shaped dough. Then baked at about 190 °C for 15 minutes for the buns, and about 35 mins for the loaf.

I am very happy with my first attempt.  They are light and fluffy with bags of lovely flavour, I suspect a lot of this is from the really good quality butter and the excellent eggs.  We have now tested the result served with some of my Wife's wild plum jam.

For the bakers reading, here is the crumb shot!

Sunday, 5 January 2014

Building a wood fired bread and pizza oven - Soldier bricks

The oven has kept me really busy this weekend, yesterday, fabricating the steel strapping and today laying the soldier bricks.  These are the last bricks to be laid before I can start the brick dome and they need to go off well so I really wanted to get this done before I head the Netherlands this week for work.  This will give the mortar a week to harden before I start on the dome.

The picture below shows the completed soldier bricks, as all the bricks are slightly different sizes I have had to choose which side of the brickwork I want to look good and as the outside is hidden by insulation, only the inside is visible, so the bricks has been aligned on the inside surface.
Completed soldier bricks
As these bricks will be pushed outward by the weight of the dome, they need to be braced by the mettle strapping.  The small gap (0-4 mm depending on the size of the brick) between brick and steel is filled with refractory mortar.

Starting to be able to see what the oven is going to look like, when finished.  Today was the first day that I looked at the oven and could imagine rows of bread baking in there.

It was much easier to work today as I finally installed some overhead lighting in the bakery.  This shot shows the transition between oven and chimney.  

From this angle I can really imagine the fire burning or the bread baking, maybe a pizza or two during the later stages of firing.  Just behind the door opening you can see the arch support bricks for the lower reducer arch.  Just realised I am going to have to write a blog post explaining my design and why I chose this over many other more popular and tested designs. That will be for another day.