Food or edible material: processes – compositions – and products – Processes – Preparation of product which is dry in final form
Patent
1984-03-26
1987-04-21
Yeung, George
Food or edible material: processes, compositions, and products
Processes
Preparation of product which is dry in final form
34 86, 426640, A23B 702
Patent
active
046595791
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a dehydration process for moist vegetables, in particular alfalfa or beet pulp.
Applicant in its French patent application No. 81 14670 filed on July 28, 1981 described a drying process which is particularly advantageous with respect to saving energy; moist vegetables are introduced in a vertical drier provided with staggered plates and heated by vapor which is recompressed by a compressor unit.
The recompressed vapor arrives in particular from an evaporator of which the tube stack is fed by the mixture of air and vapor issuing from the moist material, this mixture being made to saturate through an exchange with a cold fluid.
This saturated air-vapor mixture is injected at the bottom of the drier and takes part in drying the moist material; it acts as a vehicle for the calories, by passing from a saturated state into a state where it is capable of storing calories.
Moreover, it is known to dehydrate moist vegetables by adding a large amount of dry matter in the form of a highly concentrated solution, whereby the final proportion of dry matter of the mixture is correspondingly increased.
For instance, French Pat. No. 2,401,223 describes a beet-pulp fabrication process where the beets are treated with molasses, which consists in incorporating a large amount of molasses in the form of a solution with dry-matter content exceeding 80% (80 Brix) into the pressed pulp, and then in pressing the mixture so obtained.
U.S. Pat. No. 3,551,163 describes a recovery process for citrus pulp obtained after pressing the fruit in order to be used as feed. This process includes two consecutive pressing operations and, before the second one, re-steeping the moist matter with the juices from the first and second pressing operations. The juice is concentrated to more than 70 Brix prior to the re-steeping. In this case, too, a substantial addition of dry matter is involved.
The incorporation of a solution with a very high drymatter content does not allow adequately homogenizing the mixture, and hence the subsequent pressing operation is less efficient. This appears to be due to certain essential elements reinforcing the pectic chains, for instance calcium and aluminum being incapable of penetrating the cell spaces of the pulp when the solutions with additives are too concentrated.
A first object of the present invention is to permit improved vegetable dehydration during the pressing operation.
The invention consists in applying one or several consecutive pressing operations to these moist vegetables and is characterized by the juice from the last pressing operation and concentrated within an evaporator to a concentration exceeding 1% but less than 60% by weight of dry matter being used in steady-state operation to re-steep the moist vegetables prior to this last pressing operation. The concentration of the pressing juice is assured by the vapor or hot-gas production.
The process of the invention is particularly well suited to:
(1) Drying the pulp of beets which were subjected to a double pressing operation with concentration of the juice of the second pressing operation and recycling of this juice prior to the second pressing operation. Preferably the concentrated press juice is of a concentration less than 40% and advantageously less than 20%, and better yet between 4 and 15%.
(2) Drying alfalfa subjected to a single pressing operation with prior concentration of the press juice which is recycled. Preferably, the concentrated press juice is of a concentration less than 55% but higher than 20%.
After the last pressing operations, the moist vegetables can then be introduced into a vertical drier of which the heater elements are fed by vapor recompressed by a compressor unit. Preferably this compressor unit is fed with vapor from the evaporator of which the cold fluid is juice from the last pressing operation and of which the tube stack is fed with the mixture of air and vapor from the moist vegetables while they are being dried. This procedure is particularly economical and, furthermore, uses only el
REFERENCES:
patent: 2774671 (1956-12-01), Cotton et al.
patent: 3551163 (1970-12-01), Vincent
patent: 4058634 (1977-11-01), Kunz
Beghin-Say S.A.
Breiner A. W.
Yeung George
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