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