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About caffeinegeek

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    Brewing Nicely
  1. UK mains voltage has been 230 Volt for a while now and older 240 volt appliances with heaters will be running lower on power output even lower if you are on a long supply line in the sticks? My old bread toaster now struggles to toast bread and the elements hardly glow producing infra red. It's the same problem with older electric oven grills unless they are the 230V red quartz type. I roast with a modified toaster oven fitted with additional heaters normally running from a PID controller with a max output of 1.2kW, but I could go to 2.2kw. I've had to program my own profiles because the profiles for small roasters generally available do not take account of the thermal lag associated with my oven and drum. Temperatures measured inside the oven (air) are higher than larger pro roasters whilst drum and bean temperatures always lag. Changing the bean load from small to 500gm affects the profile, particularly once the roast starts to become exothermic. I have had a roast sitting at the start of first crack for longer than I expected when I started using oven temperatures of <200C. The PV and SV temperatures were both in track but the bean and drum temperature was still catching up. Eventually I had to increase the temperature to around 210-220C for the final roast stage which I prefer to judge by bean color. If you are able to confirm the roaster can reach and maintain this higher temperature, there should be sufficient element power unless the roast starts to become exothermic and then it's time for fans on. I suspect most small capacity DIY roasters have to be learned with a consistent bean load and experimentation to get the best from them.
  2. Hi, I thought I would start this discussion after doing some home roasting. Doing my own roasting I've discovered the roasted weight can drop by about 20% and ocassionally I've had a disaster with an over roast when going for darker. I started thinking: I've tried some of the ready roasted brands in 1Kg bags including those from Costco (Kirkland brand) and been pleased with the good taste, crema produced and consistent grind. If I want to continue with home roasting I can only justify doing it if I can buy bulk green beans 5-10kg and take advantage of the longer storage time for a green been, compared to a ready roasted bean. But when I start to cost what suppliers are charging nothing makes sense? I can buy a reasonable ready roasted bean from cash & carrys for around £8.50 a kg which is a full ready to grind kg with no water weight loss or risk of a bad roast. When I look at the cost of most bulk buy green beans they seem to pitch at over £10 per kg. If I could buy green beens for around £6 per kilo i think home roasting would be worthwhile after allowing for water weight loss and the ocasional bad roast. At the risk of being flamed, what's the point of home roasting, buying the kit, time and electricity cost and how can it make sense economically? My suspicion is green beans in bulk should be really cheap, but suppliers are cashing in on coffee fashion and DIY enthusiasm to hike up prices, whereas a ready bagged and roasted product has more competition on the shelves?
  3. https://coffeeforums.co.uk/topic/48292-when-a-diy-roast-goes-wrong/ I think you could be creating a B*omb! I can never understand why people want to set fire to decent whisky,brandy or bourbon. IMHO If I wanted the flavor I would pour it into the shot? Think of alcoholic spirit drinks as gasolene, would you want it inside a roasting oven? If you wanted to dunk roasted beans in an alcoholic drink after they had cooled from the roaster, that might be different, but I think the outer roast on a bean would make it too hard for alcohol to get through and there's always a secondary risk of explosion in the grinder. As I have already found, there is enough oil in a green been to get a fire without adding to the problem.
  4. Thanks for the tips on crack. I'm looking at what mods I can do to the roaster. At the moment I'm more confident looking visually at the roast and listening for cracks than just relying on PID automation. I'd built in manual overide for heating and fan cooling (which failed on this event) and using manual intervention to control near the crack point has so far given the best results. The issue I've not seen much discussion on is most PID controllers including those with ramp programming are only single channel. Some make misleadingly claims they are more than this by using relay alarm outputs, but this isn't the same as proportional control of temperature for both heating and cooling. The only true dual channel PID controller I've found is Arduino based, using an addon board from the States which isn't easy to get here at an affordable price. With small roasters inluding the popcorn poppers, you rely on air temperature measurements which we know are not the same as measuring bean temperature, but I've not yet worked out how to measure bean temperature with my small drum roaster. My next issue is the drum itself. Peanut roasting drums are a wire drum with lots of open hole area and very little mass. The drum itself isn't going to retain much heat so I'm making a larger drum using thicker perforated stainless sheet. That will allow the drum to be pre-heated and retain more heat before the beans go in. I can easily measure drum surface temperature which I think will be closer to outside surface bean temperature than oven air. But if there's an easy way I'd like to measure bean temperature? PS: Do you think a 500gm bean load is too risky in a small roaster? Clearly the larger the bean mass, the more heat they will store up to be cooled and this increases the risk of a thermal runaway? .
  5. I'm happy to share my bad experiences as well as good to help others. I modified a toaster oven for home roasting. I uprated heater elements, fitted a barbecue spit spindle and motor and mesh peanut roasting drum. The heaters are PID controlled with programmable ramp sequences. I kept all the original front panel controls and over heat protection. Finally, I fitted a huge fan on the rear panel. The fan is the type used for domestic gas boilers and moves a LOT of air. I started off test roasting cheap Santos beans at around 150gm per load then upped the load to 250gm. The oven fan exhaust looped out of my kitchen window and i kept a CO2 fire extinguisher close by. First attempts with air oven roasting gave me an under roasted result so I started tweaking the PID ramps, duration and temperature which aren't anything like the published profiles for professional roast ovens, although the Gene roaster seems close to mine, based on results from their users? By now I hade done 5 test roasts but still needed a darker result. I adjusted the final level temperature to 235C. I found listening for cracks hard because I'm not sure if first crack means the first bean that cracks or hold the temperature and wait for several beans to crack? I was getting more confident now and loaded up the mesh drum with 500gm of Guatemala SHB. I started the routine and watched the bean colour as the oven (NOT bean) temperature was held at 235. The cracks started to occur but I left the temperature set for another minute before starting the cooling phase. I fitted a speed controller on the fan so I could adjust the cooling rate from very fast to something slower. This is fairly easy to do manually by looking at the PID controller present value. THEN DISASTER. The exhaust fan switch/speed controller had failed and the beans were getting darker very quickly. I cut power to the oven heaters but with no exhaust fan I couldn't get much convection cooling through such a small oven cavity. The oven was filling with smoke and its temperature was RISING with heaters turned off. I could see the bean load was now in its exothermic stage and thermal runaway which I wasn't prepared for and the fire extinguisher was last resort. By this time and after I opened the oven door, the house smoke alarms had gone off creating a racket and adding to the confusion. I grabbed a fan heater, switched it to cool and held it in front of the open oven. More smoke everywhere, but the bean load was cooling down at last. When the drum and beans were cool enought to remove, they were as black as black having been self consumed of all oil and were no good for anything but charcoal. And so I learned that whatever fancy PID controller you may have on the heat side, a strong working exhaust fan (and standby fire extinguisher) is an important component to control temperature around the crack point and stop beans going into thermal runaway. I also learned the bigger the bean load in a small cavity oven, the harder it can be to stop thermal runaway! All this is unsurprising when one considers the oil content held trapped inside green beans.
  6. I was surprised nobody mentioned Pannarello? I discovered this is the design of the Delonghi frother I tried with a stainless 6-10mm DIY thread adapter I made from stainless using taps, dies and tube. An expert in fluid mechanics could explain why this design is so good at producing micro foam easily from small milk volumes every time? In fact, you can create microfoam like a soufle which stays in the cup for 10 minutes +. The trick with Pannarello tips is drawing air down the outer sleeve. Not only does this introduce air without any special angles, technique or milk rolling, but the air cools the steam as it enters the milk. This means you do not get a high volume high temperature steam jet entering the milk, bouncing off the bottom of a small pitcher and heating the milk too fast before it gets enough foam. The Pannarello tip takes longer to froth - about 40 seconds. The Delonghi tip I tried has a sliding air shut off and the trick is to cut off air at about 50 deg.C when there is sufficient foam and continue steam heating to the final temperature. This answers my question to my problem - Plenty of perfect milk frothing every time using a Pannerello frothing tip, even with different milk. The best for me so far is Asda own brand full cream.
  7. Hi all, can somebody tell me what is the outside diameter size (mm) of the steam tube on a Gaggia Classic? Thanks
  8. Thanks, I can try that. I agree it may be possible to find a technique and work fast, so I'm prepared to take longer then move up to more holes if I want faster steaming? I'll try blocking up a hole, but this will change the steam distribution as both holes are offset from the tip centre. With the single hole tip resting at the popular angle on the jugs pour lip, then moved to the side I'm getting a good swirl action in the milk without the ultra rapid fast temperature rise. I've been working on the principle that if I can produce plenty of good quality micro foam, I won't have a problem producing less, whilst tip depth can still give me heated milk without foam? I don't want to hog a thread about milk when coffee aficianados concentrate on shots. But it's frustrating when you think milk should be the easy part.
  9. So now I believe this problem arises using a commercial machine which is more suited to high volume coffee turnover in a busy shop? The volume of milk being frothed or steamed with microfoam will be a lot more than the single cup volumes I'm starting with. My Fracino Contempo 1E has a large 7 litre copper boiler, therefore plenty of steam volume maintained at the optimum 1 bar pressure. With their standard 4 hole steam tip and milk volumes around 125-150ml, the superheated steam volume and capacity to heat a small amount of liquid is huge.150ml of milk at 7 deg.C can reach 70 deg.C in less than 10 seconds. Frothing requires the physical action of 'rolling' the milk. My standard steam wand has no air admittance port I could find to mix air with steam and getting the right air mix is down to tip technique. But such a high steam volume will cause rapid heating of the small milk volume first, allowing insufficient time to roll the milk and consolidate air into it before it reaches the optimum 60-65 deg.C. In the hands of an experienced Barista it may be possible to get these small milk volumes frothed o.k. But since I've started looking carefully at the quality of frothing and many online videos, I see there's a large variation in results obtained for cappucino and latte, which are not obvious just looking at the top surface of the finished cup. I can make froth but microfoam, steamed milk that pours like Guinness looking active in a glass with micro bubbles rising upwards and stable has eluded me? Advice so far has been to concentrate on milk, temperature and technique. It's true that getting good results from a small milk volume is hard but why? - It's because the steam heating is too fast to control the amount of air through the milk stage at around 50 deg.C, although I agree it's possible with the right technique if you can work VERY fast. I decided on 2 approaches to test my theory: My steam wand with a 4 hole tip pushes out steam fast and furious, so I can't see any issue with the boiler but I can easily change the steam tip. The second test would be to try a sophistocated steam tip designed to allow air to mix close to the tip. Ideally I wanted a commercial quality steam tip. I found a steam tip spare sold for the Delonghi ECAM 22.320.SB. This is mostly plastic with a 6mm angled steam tube, a single 1.2mm hole and clever nozzle and air admittance, but won't plug in directly to a 10mm OD wand. This was my first alternative test nozzle temporarily fitted to my steam tube with silicone pipe and clips. This nozzle is a concentric design. The steam jet itself is specially moulded and there's an outer tubular 'shield' through which air is admitted. I think the idea is you don't need to incline the tip, just sit it below the milk surface and the shroud draws in air above reducing the problem of large air bubbles forming and breaking at the surface. This is similar to how a gas blow lamp or bunsen burner works. In just 2 tests with no special technique I could produce gloopy long lasting Guinness like foam in 150ml of cold milk taking about 40-50 seconds. My second approach was to try a Rancilio Silvia V3 single hole tip and compare results with the Delonghi frother. What I disliked about the Delonghi frother is its multiple components that are not so easy to clean as a standard tip and it's more domestic quality parts than solid all metal commercial. The Silvia V3 single hole tip produced the lower steam volume and much slower temperature rise I was looking for and therefore easy to find the transition temperature where the milk would roll and keep rolling a lot longer. As with other standard steam tips, it relies on technique to angle and position the steam tip in the jug, but it's far more controllable. For a commercial coffee shop, the steaming time of up to 50 seconds per 150ml is probably too long, but the foamed milk quality is excellent. The Delonghi frother still had the edge as it was pretty idiot proof and very little skill is needed, apart from looking at the digital milk thermometer. I have decided to cut the standard 10mm steam pipe about 150mm up from the steam tip and fit a threaded stainless adapter. This will allow me to fit the Delonghi frother, revert back to the standard tube and different tips, or experiment with my own version frother using an outer shroud like the Delonghi. I hope this helps those using commercial machines at home struggling with milk frothing to get good results. As I get more practice with the single hole tip, I may move back to 2 or 4 holes, but at the moment I like the control I'm getting with single hole and time to froth is less important to me than the result.
  10. With the stock 4 hole tip it takes about 12-15 seconds for the milk to go from 7-70 deg.C steaming at 1 bar. I think I might be getting somewhere because I'm sure now my technique is fighting the huge amout of steam coming out and the fast temperature rise. Somewhere around 60 deg.C I start to get the large bubbles and after that large bubbles just keep coming. This morning a Breville steam tip arrived. It's the one with the plastic push up and down sleeve to select hot milk or cappucino. It's short stubby 'L' shaped steam tube is 6mm OD whereas my Fracino is 10mm OD and 8mm ID. With some temporary silicone tubing, I attached it to my steam wand, plunged it into supermarket semi skimmed milk. It took longer and the temperature rise was slower but I got nice micro foamed milk from a small starting volume of about 125ml. Now I know this frothing tip is a designed venturi and sliding the selector just covers the air hole. I dismantled it and the single tip hole was about 1.2mm. I'm not trying these things to compete with baristas, but then single cup coffees with small volumes of milk with no waste is my challenge. If I was frothing 250ml + milk each time I think it would be easier. I bought some Cravendale whole milk and tried it with the stock 4 hole tip. The cold milk swirled with more turbidity, but that might be expected anyway compared to semi skimmed. The small volume frothing result was similar but the foam seemed more stable and sat longer without collapsing, but then this milk is twice the price! So I'm back wondering about trying a single hole standard type steam tip first to give slower heating? I shall also be engineering the Breville steam tip with a more permanent connection to my standard steam wand and do it in a way that allows me to go back to the standard tip. Mods always need a revert back exit plan! I'll let you know with some photos how it's working out if I don't give up fighting the Captcha.
  11. Regular supermarket fresh semi skimmed - Waitrose, Sainsbury - they all give me the same results. But I'll give the Cravendale full fat a try if they are using better cows.
  12. Thanks for the 'tips' (pun!), I've watched several videos but they don't tell you what to do when you don't get the same result at the end? My milk volume is 100ml which added to a single shot fills my latte glasses. That small milk volume might explain why I'm generating bubbles and coarse foam at the surface? I don't see why there should be objections to using a wine cooler? Mine is compressor driven with tight control of temperature, adjustable down to 4 deg.C, has a smaller space without the door always being opened for access to food and now we drink more coffee than wine.
  13. Thanks, I've made a small step in progress: I do use a thermometer and aim for 65 deg. C & no more than 70C. I changed the steam wand tip from 4 hole to 2 hole. Most fridges of the Eco kind like ours set their fridges to 10 deg.C when the Eco button is pressed which is a trap for the unwary! I could drop the fridge temperature but the wine cooler will do 5 deg. C which is a smaller space and doesn't get the same frequent use as the kitchen fridge. The problem as I see it now is my milk volume is too small for single cups causing the milk to heat up and aerate too quickly due to the small volume. The larger air bubbles are getting through faster before I get nice micro foam. The larger bubbles tear the milk fat apart and once this stage is reached there's no more micro foam . A larger pitcher gives better results because the frothing to final temperature can be slower and I'm doing good cappucinos, but the micro bubble froth for latte is still eluding me? Once the milk starts to froth I'm getting larger froth bubbles sitting like foam on top of the milk. Just for an experiment I've ordered a Breville auto frothing tip to try on my 10mm steam wand to see if getting air into the milk through a venturi tip design gives a better froth. I'm also aware that steam tips come in different hole sizes as well as the number of holes. I think my problems arise because I'm not in a cafe business frothing 1/2 litre of milk at a time. Just to give me an idea, how long should it take for a given volume of milk in your pitcher to reach temperature? I didn't think frothing fresh milk for micro foam would be so hard. The boiler is putting out steam at 1 Bar with no water after purging the wand and the only thing left can be the tip, how air is mixed and my technique?
  14. Thanks, that ties up when I said frothing 2 cup volumes seems better. But if you want just one cup of coffee, do you froth more milk and throw milk away? I suspect the best milk froth occurs when the milk is coldest and my small milk volume heats up too quickly? I think I will try some milk in my wine cooler which is at about 7 deg C and a lower temperature than the fridge. When I do the hand hold temperature check I find my coffee seems too cool? Perhaps that is how it should be compared to boiling water over instant. I was in Italy last year during Winter and the first Latte I had seemed too cold for my taste, but I was told the Barista had been taught by his parents over many years so I wasn't going to argue! Does your milk froth pour out of the jug nicely or stick around the sides like mine?
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