Colloid Mill Add-on: Hopper Enclosure, Feed Regulator and Ventilation

colloid mill add-on bottom view

colloid mill add-on top view

This contraption does three things.

1) Regulate the in-feed of cacao nibs inside mill. Just turning the motor on and filling in the hopper with nibs to capacity won’t work. It runs for few seconds, slows down, clogs and stops. It is actually a homogenizer designed for liquid materials. However, regulating the feed to some point make it usable for grinding cocoa nibs.

2) Prevents nibs from flying out of the hopper. The spiral drive just above the rotor was designed to suck liquid in. However, the material I am trying to grind is somewhat similar to corn grits. Some are sucked in successfully some are not and end jumping out. It is so frustrating to see the nibs I worked hard for are just flying off to ground.

3) Inject air inside hopper. It helps cool down the mill a bit and facilitate escape of evaporating acids. In absence, it condenses on sides of hopper and my diy contraption. It is so messy.

Still made of thin plywood, pvc pipe scrap, HDPE plastic sheet and screws. Revising as needed and plans on building a stainless steel version once finalized. It is not in the near future, I think.

Marvin is the lead chocolate maker of Ben and Lyn Chocolate Inc. Has strong background in food research and development. Occasionally conducts training and lectures. Lecturer of Cocoa Foundation of the Philippines. Do coaching and consultancy services on his free time.

Making Chocolate Bars | Colloid Mill as Grinder/Refiner

First of two articles which were left in my scratch pad. I guess it is not too late to publish them here.

First Trial

This my first real chocolate trial using the colloid mill. I tried the regurgitate feature and it worked well. The result was a silky smooth pure chocolate. I tried adding sugar while regurgitation was in process but it was not working the way I want to. The liquid was too viscous to dissolve all the without intervention.

Second Trial

About 15% sugar added to liquor before grinding with the regurgitator. It was working fine but I should not load too much on the hopper. Still experimenting how much it could carry. Perhaps additional butter will make the liquor more fluid and operation smoother. It was not available and I have no plans on getting some.

The liquid chocolate tasted just right. I can say it was awesome for my first trial. I did not left anything for molding though. It think it calls for verification trials.

Third Trial

About 50% sugar added and mixed to liquor before grinding. I removed the regurgitator tube this time. The high speed and low torque mill could not handle the load. I poured it slowly and let flow down the spout.

Too much sugar and too much heat build-up were bad things. The taste was too sweet with a strong bite of burnt taste. I should reinforce the cooling system and reduce sugar quantity. Too much sugar is not healthy so I should keep it low.

I produced a surplus of 50%/50% mixture. I moulded them all in ice tray mold. The chocolates were absorbing moisture after a while and forming droplets that never dries out.

The droplets I am referring to are still there after few days. I am guessing they are patches of syrup. I wonder what could have caused it.

Marvin is the lead chocolate maker of Ben and Lyn Chocolate Inc. Has strong background in food research and development. Occasionally conducts training and lectures. Lecturer of Cocoa Foundation of the Philippines. Do coaching and consultancy services on his free time.

From Manual Grinder to Colloid Mill

There are two factors that stopping me from boosting and improving cocoa processing. The first is the lack of budget and the second is the unavailability of cocoa processing equipment. They are available globally but not locally. Getting them outside of the country means passing thru needle hole set by Customs. Pardon me please!

The very first grinder we could afford was the Baesa hand operated corn mill which was modified to run on 0.5HP motor. I was a great relief at first. We don’t have to burden anymore the very difficult mill manual operation. Imagine grinding a kilogram would take about an hour with a very rough output.

Production have increased and we managed serving more customers. However, feedback also came in. They wanted a finer cocoa liquor texture. Our mill was motorized anyway so we did our best to pass the liquor thru grinder several times. We were doing around 2 to 4 passes depending on my mood. Often 2 because I was always out of my mind busy doing other things. Four passes was resulting to a fine liquor texture but not fine enough to suit more than 50% of critique.

After several years, the Baesa motorized mill broke. We didn’t have a back-up plan we bought a replacement grinder with very little planning. Correction, that was an impromptu buy. We bought a cheap stone type grinder for soya. Stone burrs are good in the sense that they never build heat fast. I thought I could pass the nibs and then the liquor several times. The two HP grinder could barely handle the load. The placement of nibs on hopper should be continual, about a tablespoon each time at interval of 5 to 10 seconds. Second pass was okay but the third and fourth were not. The gap between burrs should be adjusted closer to each time to get a finer texture. However, the cocoa liquid was serving as sticky glue binding the two stone together. The last thing I never like with stone grinders, they were damn hard to clean. I am hiding it from food safety inspectors and other critics to avoid flagging.

We got the colloid mill. It’s specification sheet never lied. It can really do a very fine grinding with just one loading. The result is very very far from motorized Baesa corn mill and cheapo soya grinder. It has still some drawbacks like fast heat build-up and high electricity consumption. I did some simple tricks to drive away too much heat and still testing some to control it completely.

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Marvin is the lead chocolate maker of Ben and Lyn Chocolate Inc. Has strong background in food research and development. Occasionally conducts training and lectures. Lecturer of Cocoa Foundation of the Philippines. Do coaching and consultancy services on his free time.

Colloid Mill – Regular Cleaning

Base on my last record, it can easily grind 10 kilograms cocoa nibs for 40  minutes. It is very fine and second pass is almost not needed. Then, why was the grinder seemed taking a hard time. I was exactly doing the same procedure as before. It took me twice longer to finish the same batch quantity. Something must be terribly wrong.

For cleaning, I usually let several batches of water circulate for several minutes until the water is visibly clear. I took off all the parts this time for general cleaning and perhaps see if there was something wrong with the mill. I was surprised I saw a hardened cocoa underside the rotor and between the rotor and shafting. This must be it, it was creating friction making the motor to lower its speed, and even slower to the point it stopped when nibs were added in hopper.

cleaning first passI achieved the desired milling record for the next batch. I included regular mill cleaning as part of cocoa processing chores.

parts removed and cleaned

Marvin is the lead chocolate maker of Ben and Lyn Chocolate Inc. Has strong background in food research and development. Occasionally conducts training and lectures. Lecturer of Cocoa Foundation of the Philippines. Do coaching and consultancy services on his free time.

Colloid Mill, First Use

colloid mill with rotor exposedWith the knowledge in mind, cocoa nibs when hot is a lot easier to grind. Cocoa butter which is solid at room temperature becomes liquid when heated. It readily flows out of the rotating burrs. Unlike the cold nibs, the burrs friction need to sufficiently heat the butter first before it flows out. This slows down the grinding and made the rotor harder to crank putting burden to motor (hands in case of manually operated grinder).

Gap adjustment. I made sure the mill was unplugged. I took out the hopper. Rotated the adjustment knob while manually rotating the rotor with a vice grip, until the rotor and stator surface touched it other. Then, rotated back the adjustment until I could turn the rotor freely without touching each other. Lastly, installed the hopper back.

About 400 grams nibs. Turned the machine on and slowly poured down the hot nibs. After few seconds, the liquid and finely ground cocoa liquor was pouring down nicely. It was a very nice development. The four times pass in my ordinary stone grinder and a DIY steel burr grinder were nothing compared to this.

The next problem was heat issue. The metal part becomes terribly hot to the point that it burns and boils the cocoa liquor. I should have supply the cooling feature with water from the start. This equipment has inlet and outlet for flowing water to fend off heat.

The six kilograms trial. I set up the next trial, but this time, I prepared six kilograms. I also bought a water pump to feed the cooling feature with water. The setup was, six kilograms cocoa nibs, colloid mill, water pump and a pail of water.

Resulting failures:

1. I setup the rotor / stator gap too tight. The cocoa solidify to the point that it could hardly get out. Widest possible setting of zero is enough to liquify the cocoa and get it out of the faucet. Careful fine tuning could be done while the machine is running.
2. One pail water was not enough as coolant, two were not either. I should install a large radiator with fan next time. A car radiator perhaps. Preparing a larger water reservoir should also be in my list. It is a nice precaution in case the radiator I selected has weak cooling capacity.
3. I got few scorches by monitoring the mill temperature with bare hand. A thermocouple or infrared heat sensor should be available next time.

Well, it was a nice learning experience. I am pretty sure I can master it very soon.

Marvin is the lead chocolate maker of Ben and Lyn Chocolate Inc. Has strong background in food research and development. Occasionally conducts training and lectures. Lecturer of Cocoa Foundation of the Philippines. Do coaching and consultancy services on his free time.