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Critique my roast profile (+technique)

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  • zuroy
    replied
    Thanks I have a steel elbow but it might be a bit too long (20cm each length and 40mm diameter) so I wasn’t sure if that was affecting my roast flavours. I did a roast yesterday without the steel and just let chaff fly everyone so I’ll compare.

    Nedplimpton - I used a fire blanket as insulation and that’s at Bunnings for under $10 (and you’ll have plenty to spare).

    Leave a comment:


  • Lyrebird
    replied
    Originally posted by zuroy View Post
    Thought I’d piggyback off this with some further questions.

    Any feedback on the airflow setting in the heatgun?

    Assuming most heatguns have two (low and high) settings, do you keep it on high airflow throughout the whole roast?
    Mine has three but I leave it on the highest setting at all times. I find lower flows give more "bakedness" as I found to my cost when the Makita was clogged up.

    My theory is that baked flavour is actually caused by the coffee stewing.

    Originally posted by zuroy View Post
    Also how do you handle exhaust?
    Do you leave ~25% of the lid off permanently or do you progressively widen the lid gap as the roast goes?
    I have a 40mm hole in the silicone foam pad that fits a stainless steel elbow that exhausts into a wine box with a cloth lid (a BeanBay bag) as chaff catcher. Easy for me I have spare stainless fittings etc lying around.

    I tried connecting it to a full scale workshop dust and chip extractor but this seemed to pull too much hot air away from the coffee so it was counterproductive.

    Leave a comment:


  • Lyrebird
    commented on 's reply
    Ordinary rockwool for the sides, I align the joint so the thermocouple fitting doesn't push the rockwool down. I cut a lid to fit the breadmaker from silicone foam (sold as ironing pads).

    I tried ceramic oven insulation but it is too fragile.

    The insulation value will be set by the pan spacing. Mine has about 25mm clearance between the pan and the sides of the breadmaker so that gives you about R 0.5 (common insulation is all clustered around R 20 per metre thickness)

  • flynnaus
    replied
    Originally posted by zuroy View Post
    Also how do you handle exhaust? Do you leave ~25% of the lid off permanently or do you progressively widen the lid gap as the roast goes?
    I have the Bosch 2000w variable temp heatgun that Lyrebird mentioned. It has three fan speeds. I worked out my own roast profile based on the profile Mal developed.
    I use a ceramic tile for a lid which covers almost half of the bread pan. I direct the HG to one side of the opening and use a fan to blow the chaff and exhaust away and don't need to adjust the gap during the roast.

    Leave a comment:


  • Dimal
    commented on 's reply
    I'd go for a Lid and Insulation first, little cost and significant benefit.
    You can then grab a new Bosch HG or similar at some future date from one of the big Tool Retailers that do online sales...

  • Nedplimpton
    commented on 's reply
    What type of insulation do you use?

  • Nedplimpton
    commented on 's reply
    I purchased a rockwell heat gun as it had more control than the Makita that was available nearby (tried to find bosch too, no avail).

    It has 3 temperature settings: 25°C / 350°C / 550°C

    I keep it on high flow (550*C) the whole roast. The 350*C flattens out the curve completely I find.

    Not lid, no exhaust, I just keep the lid open and direct the gun down into the pan. Looks like I might need to tinker.


    What should I try 1st? Insulate / build a lid / new heatgun?

  • WhatEverBeansNecessary
    commented on 's reply
    I have the ozito heat gun (cheapest with variable temp) and find I only use the lower fan setting. The higher speed I can't hear first crack well enough and have heard but not verified the higher speed dries the beans out too much.

  • zuroy
    replied
    Thought I’d piggyback off this with some further questions.

    Any feedback on the airflow setting in the heatgun?

    Assuming most heatguns have two (low and high) settings, do you keep it on high airflow throughout the whole roast?

    Also how do you handle exhaust?
    Do you leave ~25% of the lid off permanently or do you progressively widen the lid gap as the roast goes?

    Leave a comment:


  • Lyrebird
    replied
    Might be worth simply upgrading the heat gun. I went to the Bosch 2000W gun with the digital readout after blowing up the equivalent Makita. Available for about $150 from tool shops including big green shed, that's the equivalent of about 6 kg of coffee.

    Also, insulate the pan on the breadmaker, reducing heat loss improves consistency for basically no money if you have access to rockwool or similar. If you don't I'll give you some for the cost of shipping.

    Leave a comment:


  • Nedplimpton
    commented on 's reply
    I think unfortunately my heatgun doesn't push enough air between setting 2 and 3. At 3 it's too hot, and at 2 my curve flattens right off. Might need to raise the heatgun instead.

  • Lyrebird
    commented on 's reply
    Horses for courses. I keep air flow at maximum and reduce inlet air temperature in several steps over the course of the roast. One or two of these steps are usually after the probe temperature has passed 200 oC so that would put them after first crack (I don't bother tracking FC as I don't think it matters).

  • WhatEverBeansNecessary
    commented on 's reply
    Generally (and it depends on your batch size, heat gun, ventilation etc) I keep it about the same or just bump it up slightly.
    Keep in mind once you hit FC the beans go from endothermic to exothermic (slightly) so they produce heat rather than consume it (this is super simplified 'chemistry' of it all) - but you also need to continue to increase the temperature. So will be a balancing act between beans heating themselves and adding in extra heat.

  • flynnaus
    commented on 's reply
    Yes. If you go too quick after first crack, you risk scorching the beans. Too slow and you risk stalling the roast. Google RoR (ie rate of rise) for more info.

  • flynnaus
    commented on 's reply
    I have found that the larger batches easier to manage in the 400g+ mark. The roasts are less sensitive to changes in heat input.
    Yes, that's right. Too small and it's harder to maintain a steady temperature rise. Too big and the roast times blow out potentially resulting in loss of flavour
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