Food Engineering/Manufacturing/Washing sesame seeds


Dear Sir,

We are a manufacturer of organic sesame seeds in India.
Our present operation goes like this. First we fill a tank(half) with water(including a chemical that removes all the impurities) and then we soak 1 tonne sesame seeds in that tank. Keep those seeds soaked in water for 10 minutes and then open the valve which is at the bottom of the tank as the seeds comes out. Below we put small crates having perforation to collect the seeds, and water drains off through the perforation. At the same time we wash the seeds in the crate with plain water to ensure lowest ppm of chemical in the seeds. We need 10 such crates to empty the full tank. And than after all the water drains off we lift the crates, manually, carry them to the alloted open space to sundry. We have only 1 tank and our production is 10 tonnes per day. So we have to do this whole process 10 times a day.

I want to make this process fully automatic. Please sujjest the ways and machines and operations that will make this process easier for us. Sujjest something like at one end raw sesame seeds are fed and at the other end fully washed seeds are collected in the crate. I mean to say something online. Not batch wise as we do at present.

The challenge is how to transport the very small sesame seeds without losing too many.One approach might be to use a screw conveyor set at about a 45 degree angle. Washing solution could be sprayed at the top discharge and would drain down the screw body while the rotating auger would carry seeds up the incline. At the discharge, the seeds could drop to the inlet of a second similar screw conveyor with fresh water sprayed at its discharge. I am assuming that the seeds do not require a ten minute soaking in a continuous operation. The objective is to wash the surface without the seeds absorbing too much water. At the discharge of the second screw conveyor, the seeds could drop into the same crates now used. Those could be indexed on a belt conveyor and removed after being filled. One person could supervise that station. No other people are needed except to feed the seeds into the system. Others would deliver crates to sun drying, if that is acceptable. Drying might go faster with less water absorption. In India, sadly, water quality can be an issue, so wash water should be potable (drinkable). Wash solution and rinse water could be collected from the feed end of the inclined screw conveyors and reused or discarded. some fresh solution is needed to replace what is dragged out with the wet seeds. Screw conveyors do not completely discharge because there must be clearance between the auger and the semi-circular body. This is where the liquids flow and there will be a thin layer of seeds there as well, but the liquids will continuously wash seeds back into the bulk flow. Screw conveyors of stainless steel are common items. To handle about one ton per hour would take a screw of about six inches in diameter with about a one horsepower motor.  

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J. Peter Clark


How various processed foods are made; ways to improve manufacturing; how to make a new food product.


Employment history: Research Engineer, U.S.Agricultural Research Service, Associate Professor Chemical Engineering, Virginia Tech, Director of Research, Continental Baking Company, President, Epstein Process Engineering, Inc., Vice Presdent Technology, Fluor Daniel, Inc., Consultant to the Process Industries

Organizations: American Institute of Chemical Engineers (Fellow) Institute of Food Technologists, American Association of Cereal Chemists, American Association of Candy Technologists, American Society of Agricultural Engineers,

Publications: Several Encyclopedias (Kirk and Othmer, Chemical Technology; Food Science, Food Technology and Nutrition; Wiley Encyclopedia of Food Science and Technology; Encyclopedia of Life Support Systems); five books, two book chapters; numerous journals.

Education: BSChE Notre Dame PhD University of California, Berkeley

Awards: AIChE Food, Pharmaceutical and Bioengineering Division Award 1998

Clients: Major food processing and pharamaceutical companies.

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