|FOOD CHAIN No. 14 - March 1995 (ITDG, 1995, 16 p.)|
In past issues of Food Chain we have described a simple, cheap and novel way of making a light tomato puree. Essentially the method involves allowing a puree of tomato (with skin and seeds removed by sieving) to hang for two or three hours in a fine muslin bag. During this time clear 'water' runs out and the final weight is reduced to a third i.e. a three-times concentration has taken place.
A number of readers have contacted us and expressed considerable interest in the method and we understand that workers in Peru have tried this and hope to set up a small commercial processing plant in the near future.
The puree produced by this system is still low in solids when compared to commercial tomato paste (about 20 per cent solids compared to 30 to 35 per cent).
Major Gupta from India has written suggesting that the use of a de humidified air drier might be able to effect the final concentration without the need to resort to vacuum concentration. His company makes such driers, trade name Bry-Air
Dehumidifiers, and it is claimed that the smallest model in the range can remove 2lbs of water an hour.
Essentially driers of this type involve drawing air over beds of a desiccant suet as silica gel or salt. The desiccant remove, moisture from the air which leaves the unit with a very low relative humidity. If this extremely dry air is then passed over trays of the tomato concentrate, it should remove more water, giving a higher degree of concentration.
After use the desiccant needs to be redried. In a tropical climate the sun should be sufficient.
Major Gupta may be contacted at Arctic India Sales, 20 Raipur Rd. Delhi 110054 Alternatively, readers may contact IT.
We really feel that this is an area deserving investigation; a method of makeing a tomato puree with all the fresh flavour of the fruit, no heat damage and minimal energy inputs must be worth looking into. Could, as the Major suggests, a similar method be applied to fruits such as mango or papaya?