CH433936A - Process for preserving multicellular products of biological origin - Google Patents

Description

  

      Method for preserving multicellular products of biological origin The present invention relates to a method for preserving multicellular products of biological origin,

   by freezing these .products at low temperature followed by dehydration of the frozen products by reheating under deep vacuum to a temperature not exceeding their freezing point.

   This process, which applies more particularly to vegetables, fruits, seeds, as well as to meats, fish and crustaceans, is characterized in that the products are frozen at a temperature between -200 C and -1500 C.



  The dehydration is preferably carried out until the humidity drops to a point varying, depending on the case, between 0.2% and 40%.



  Products which have undergone this preparation are liable to be stored for several years. When the time comes for their consumption or, in other cases, for their replanting, they are rehydrated in a suitable medium and then regain, in their almost total integrity, their intrinsic nutritional or vital qualities.



       Rehydration takes place quickly and sometimes in less than a minute with the right kind of vegetable or fruit or <B> </B> treatment, which is the case with fungi.



       The invention will be illustrated below by some examples relating to various plants. <I> Example 1 </I> Vegetables are peeled, cut into slices or cubes a few centimeters thick, washed and bleached in boiling water - or - in steam, and finally drained.



       Prepared in this way, the vegetables are frozen, by any appropriate means, at a temperature of the order of -20 ° C., but liable in certain cases to be reduced to -150 ° C.

   The vegetables are then dehydrated, under a deep vacuum by reheating, without the temperature at the end of the operation rising above the freezing point of the vegetables, eg leaving -20 C or -100 C .



       The humidity is thus reduced to around 0.2%. At the time of their consumption,

      the vegetables thus treated are rehydrated in suitably salted cooking water. The cooking time; is significantly reduced by the process according to the invention.



  The cooking time can vary from 3 to 10 minutes approximately. Depending on the nature or treatment of the product.



  A similar or analogous treatment would be applicable to any variety of vegetable or fruit. <I> Example 11 </I> Paris mushrooms, peeled, washed and cut into strips of 1 to 5 mm, are immersed in a frying of boiling oil so,

      to hang 40 to 60% of their initial humidity. Once drained, they are frozen by any suitable method, the freezing temperature not having to drop below -200 C.



  Dehydration then takes place under a deep vacuum until the water loss reaches 95 to 98%.



  At the time of consumption, the pieces of mushrooms thus treated are bathed in an appropriate broth and the rehydration takes place instantly,

      knows about 10 seconds. <I> Example 111 </I> Either seed seeds containing 6 to 15% moisture. This humidity point is reduced to around 1%.



  These seeds, put in rapid freezing at a temperature of -400 C or at a temperature lower than -1001) C, are then locked in a suitable apparatus, under deep vacuum, in order;

          to remove an important part of the humidity without destroying the genital power. This vacuum can be pushed up to. 5 thousandths of a millimeter Hg.

   The end temperature should not exceed the freezing point. The humidity point should be lowered to around 1% or 0.2%, and sometimes, depending on the variety,

          until. 2 or 3 0/0.



  <I> Example IV </I> Either onions; or bulbs, of seed of a caliber varying from 2 to 12 mm in diameter.



  These onions are frozen at a temperature below -201) C, and down to -1000 C.

    The dehydration, which is carried out by any suitable means, under deep vacuum, without the temperature rising above the freezing point, is pushed until the bulbs or onions present only humidity of the order of 1 to -2% <U> at, </U> less. After conservation: which can last;

  several years, one replant in ground, with suitable humidity,. to obtain the shoots of onions and a vegetation, normal.



  In certain cases, the plants to be treated will have to undergo a preliminary soaking for a period of half an hour to an hour in suitable solutions of the water -I- -salt -i- glycerin type at various concentrations; or else water -f- sugar -f- salt -I- glycerin;

    or finally.



       water -E- boric acid -h- glycerin. Freezing can be carried out either by liquid nitrogen or by liquid air.



  The various stages of the dehydration operations - otherwise known as lyophilization - are carried out in a manner known per se: the products to be treated are spread out on mobile trays which are placed on heating plates, inside an enclosure under deep void.

 

Claims (1)

CLAIM Process for preserving multicellular products of biological origin, by freezing these products at low temperature followed by dehydration of the frozen products by heating under deep vacuum to a temperature not exceeding their freezing point, characterized in that the products are frozen at a temperature between -200 C and -1500 C. SUB-CLAIM Process according to claim, characterized in that the dehydration is carried out until the moisture content of the products is between 0.2% and 4%.