| Preservation of bio-degradables is an | | | | years. Structural deterioration due to porous |
| important aspect. Traditionally Sun drying of | | | | surface left behind by ice crystals worsen |
| pulses and some vegetables constituted | | | | the things.However, these technical problems |
| preservation. Sunlight not only removed | | | | can be overcome by common table sugar which |
| maximum moisture but also its UV rays killed | | | | inhibits ice crystal growth as well as |
| micro organisms facilitating longer shelf | | | | prevents denaturation.Brine shrimps, |
| life. An advantage of Sun drying is that the | | | | nematods, seeds are lyophilized(freeze dried) |
| natural taste would return upon | | | | in presence of sugars to prevent complete |
| reconstitution.Air and water tight packing in | | | | desication. Structural decay may be taken |
| polyethylene/PVC lined aluminium foils and | | | | care off by chemical fixatives like |
| aluminium lined tetra packs provide advanced | | | | formaldehyde and glutaraldehyde and storing |
| protection from atmosphere. The sea food, | | | | in oxygen in water tight and air tight |
| meat, pulses etc. can be packed with natural | | | | containers.The post production sterilization |
| freshness. When stored in deep freezers, | | | | or autoclaving of containers of injectables |
| these would retain their natural freshness | | | | being not possible in most cases, freeze |
| for longer periods. One aspect to note with | | | | drying comes to the rescue.The rise and fall |
| such packing was that asceptic cleaning or | | | | of temperature and pressure being absent in |
| sterilization was difficult in large scale | | | | lyophilization, keeps the nature of fluids |
| production.Food grains, in large quantities | | | | intact. The freeze dried products can be |
| may be exposed to nuclear(gamma) radiation | | | | stored at room temperature.The principle of |
| which destroys micro organisms, germs and | | | | freeze drying is sublimation. Meaning that, |
| rodents. Bhaba Atomic Research Center in | | | | under low pressure(0.06 atm) or vacuum, solid |
| India has developed a technic for exposing | | | | water converts directly to gaseous form.The |
| the food to such radiations. This is now in | | | | disadvantage with cryogenic preservation is |
| effective use and is proven a boon for mass | | | | the enormous cost over long periods. But |
| scale storage and longer shelf life.However | | | | liquid nitrogen(cryogenics) has its own |
| human organs, corpses or dead pets etc. were | | | | advantage that it prevents frozen tissues |
| stored in cryogenic state(upto -180 degree | | | | from suffering from other water and oxygen |
| Celisus produced by LN2), a technique not | | | | dependant deterioration.The author Rajgopal |
| suitable for vaccines.Freeze drying removes | | | | has been writing on technical matters and in |
| water content upto 98% (depending on duration | | | | this avtar he gave up tags that confine to |
| of freeze drying) while retaining nature of | | | | particular genre of writing. Rajgopal is a |
| ingredients.The argument against freeze | | | | mechanical engineer and served the |
| drying is that it is destructive of tissue | | | | pharmaceutical industry. Oflate he has been |
| structure and leaves the dried food with a | | | | putting his efforts in to creative art and |
| woody texture formed due to ice crystal | | | | healthcare writing. Here he looks in to the |
| growth during freeze drying. The leftover | | | | nostalgic aspect of humanity. |
| moisture leads to deterioration after a few | | | | |