Before grinding cacao nibs, I am removing the bearing part and lubricate it with my own made lubricant. The lubricant is non other than liquid cacao. It contain enough butter/oil to lubricate the moving balls. Seems funny but it is the safest way to lubricate it. Other lubricants such as mineral oil, car engine oil and singer oil are definitely not fit for the purpose. They are not specifically designed for food production purposes.
After a series of readings, I learned that there are lubricants specifically designed for food contact. I never know where to buy it locally so I found it not very useful.
update as of December 2016
Silicone type lubricants are the best for food applications. It is inert and generally safe. However, grease, either food safe or not, should be prevented from food contact. Minute amount may alter quality.
Silicone grease is a bit expensive. I shelled out almost a thousand pesos for a 20 gram pack. The Mares Silicone Grease. Hope there are cheaper alternative out there.
A friend of mine told me about the KY Jelly. It is a sex lubricant that they use for greasing bearings and drive chains. Try it if you want!
I also learned the use of ceramic bearings is more appropriate than steel balls. Speed of rotation curves out the metal slowly. The fine metal particles obviously goes into food. This reality should be corrected by using ceramic bearings.
Ceramic bearing posses the advantages over steel bearings:
1) Ceramic in ball form posses twice the Rockwell hardness of steel ball. I never thought ceramic can be twice as hard of steel ball. The ceramic I know are plates, cups and drinking glass. They are very fragile.
Rockwell scale is the measure of indentation hardness, the property to resist deformation. Most steel are pliable and can be pounded into variety of shapes.
2) It is more durable and longer lasting.
3) It can operate under extreme heat.
4) It resist heavy loads. More work could be done every batch.
5) It will not corrode or rust when exposed to acid, water and other chemical of food preparation.
6) The spherical shape of ceramic ball is more perfect than steel ball. It reduces friction making the parts rotate faster or with less energy. More efficient.
Ceramic bearing is more appropriate for food processing and food packaging operations but I never know where to buy it locally either.
image courtesy of boca bearings