Low Temperature Roasting w/ Criollo

[Brad]

Alan;

In your hypothesis, you are not accounting for the fact that most of what you read in relation to roasting beans of any type relates to roasting done in a professional roaster which uses forced air. Consequently the temperature is as much as 20-30% lower than in a standard oven, or the times are considerably shorter.

Time is a factor in any commercial environment - especially when faced with supplying today's demanding consumer with a fresh product quickly. This is why convection is so prevalent in many commercial kitchens, and also why most commercial roasters use forced air - the business wants the same result in a fraction of the time.

I've used convection commercial convection ovens for many years. Here is an example:
Cooking thick crust pizza with 8 toppings:
Convection oven @ 450 degrees: 4 minutes and 40 seconds
Standard oven @ 450 degrees 15-20 minutes

It's all about air flow.

The same principle applies to beans.

[Alan]

brad said:

Alan;

In your hypothesis, you are not accounting for the fact that most of what you read in relation to roasting beans of any type relates to roasting done in a professional roaster which uses forced air. Consequently the temperature is as much as 20-30% lower than in a standard oven, or the times are considerably shorter.

Time is a factor in any commercial environment - especially when faced with supplying today's demanding consumer with a fresh product quickly. This is why convection is so prevalent in many commercial kitchens, and also why most commercial roasters use forced air - the business wants the same result in a fraction of the time.

I've used convection commercial convection ovens for many years. Here is an example:
Cooking thick crust pizza with 8 toppings:
Convection oven @ 450 degrees: 4 minutes and 40 seconds
Standard oven @ 450 degrees 15-20 minutes

It's all about air flow.

The same principle applies to beans.

Actually, in my thinking, I am accounting for this, or at least am trying to. What my thinking leads to may not actually work, but it is based on the idea you have brought up. I have probably not made that clear in my previous posts.

This is why I am using an extremely thin cookie sheet, spreading the beans out so that they aren't touching each other, and keeping them in one single layer. This is, in my estimation, the closest one could get in an oven to approximating the airflow of a drum roaster, though I know that it is still not equivalent. In other words, since I can't actually change the flow of the air, I change the way the beans are arranged in the oven to give the best access of the air flow that there is to each single bean.

In fact, every decision I'm making is an attempt to approximate that type of roasting system. But, ultimately, I may still be on the wrong track. Only time and taste will tell. I simply can't stop thinking of the cookie example. if the cookie is overcooked on the outside and raw in the middle, then the temperature must be turned down. That is what I continue to do with the beans. If they are over-roasted on the outside but good on the inside, then the temperature is too high. This seems especially the case with beans that need the mildest of roasting (such as criollo) with a roast just a bit stronger the requisite dehydration.

At any rate, I roasted some samples at 215 F tonight. As usual, the actual range is quite varied, from 177-239 F. I pulled beans at 10, 15, 20, 25, 30, 35, and 40 minutes.

Basically what I am looking for is a bean with the most subtle roast all the way through the bean, but yet without raw "off" notes and too much acetic acid (the vinegar smell).

If I don't hit it this time, I'll take these results and rethink things. Basically I'm going for showcasing the "true" nature of the bean by not adding anything but the minimal amount of sugar, and not depending on flavor enhancers like vanilla. I know it is still subjective, but that is how I would put into words what I'm doing. To me, that's what this is all about.

I'll post my newest bean results tomorrow. I've just had dinner and so won't be able to accurately taste for some time.

Alan

[Alan]

Alright,

As I have mentioned, I roasted some Ocumare on a thin cookie sheet in one single layer with the beans not touching (i.e., not crowded together), at 215 F.

The actual oven temp. ranged from 176-239F.

I pulled at 5 minute increments starting at 10 minutes and going up to 40 minutes.

I tasted the 15, 20, 25, and 30 minute beans.

The 15 minute beans were obviously still somewhat under-roasted (if you want to know what I mean, chew up part of a non-roasted, winnowed, bean and then spit it out) and a bit astringent.

The 30 minute bean was obviously too bitter and over-roasted.

That left me to choose from the 20 and 25 minute beans. They both had their good points. The 25 minute had only the slightest hint of acid, a very brittle shell, and a stronger nuttiness. However, the bitterness was quite noticeable, and seemed a bit strong. I compared with the 20 minute.

The 20 minute had the minimal bitterness with some more acid than the 25, and a more subtle, less-developed nuttiness than the 25.

My thinking goes like this:

I will choose the 20-minute bean for my next batch because I will be conching for 72 hours since I now have a set up that stays at around 150 F (picture to come), so some of this acetic acid is going to be driven off at a later stage. Additionally, when that happens, I expect the nuttiness will be more prominent, especially with the relative absence of bitterness. Also as oxidation and various enzymatic processes occur during the conching, the fruitiness will likely increase, and any small amount of extra acid will fit right in. Finally, the hull/husk was relatively brittle, leading me to think that enough dehydration of the bean has occurred. So, that is what ultimately led to my decision to go with the 20-minute bean. As I've said before, only making a batch will allow me to see if my thinking is correct. It will be done 72 hours from tonight, and I'll let everyone know how it tastes.

Alan

[Alan]

Good news. ;D

I believe that I'm on the right track with this roasting theory. Compared to the last Ocumare batch I made, what I just tempered tastes like gold. The bitterness is much reduced when compared to my last batch (though still too strong for my taste) and the subtleties of the bean are now noticeable. They weren't in the last batch. The acidity is very, very low. Too low for me. I think that with the next batch, using the method I mentioned above, that this will be corrected and there will be more balance.

I didn't find the time to start that new batch today, so I'll roast tomorrow and start it tomorrow. I'll keep you posted...it'll be done Wednesday. I'll take that photo of my conching setup tomorrow too. It is pretty nice, and stays at a constant 149 F.

Alan