CONTROLLED ATMOSPHERE STORAGE

CONTROLLED ATMOSPHERE STORAGE : 

CONTROLLED ATMOSPHERE STORAGE BY: MUN PAL (06FT327) DIVYA SAGAR (06FT310)

CONTENTS : 

CONTENTS WHAT IS CAS? TECHNICAL ASPECTS METHODS OF CAS WHAT ARE ITS ADVANTAGES? WHAT ARE ITS DISADVANTAGES? CONCLUSION REFERENCES DISCUSSION

WHAT IS CAS? : 

WHAT IS CAS? IT IS STORAGE OF HORTICULTURAL COMMODITIES UNDER CONTROLLED O2 AND CO2 IN THE SOURROUNDING AT BEST SUITED LEVEL OF TEMPERATURE. O2 → 5% , CO2 → 1% : FOR FOOD PRESERVATION IN GENERAL O2 LEVELS ARE REDUCED AND THE CO2 LEVELS ARE INCREASED FOR THE FRUIT PRESERVATION. TEMP. DEPENDS UPON THE TYPE OF FRUIT OR VEG.

(….CONTD) : 

(….CONTD) GAS COMPOSITION DEPENDS ON AMOUNT OF PRODUCT RESPIRATION RATE RESPIRATION QUOTIENT EXCHANGE RATE BTWEEN STORAGE ROOM AND SOURROUNDING, STORAGE ROOM AND SCRUBBER.

TECHNICAL ASPECTS : 

TECHNICAL ASPECTS EXCHANGE OF GASES TAKES PLACE BY MASS FLOW BY VENTILATION OR LEAKAGE DIFFUSION PERMEABLE MEMBRANE AIR FLOW CHANNELS ATM. COMPOSITION REMAINS CONTANT FOR SEVERAL WEEKS WITHOUT ANY CHANGES AND IS INSENSITIVE TO THE CHANGES IN BAROMETRIC PRESSURE

(…CONTD) : 

(…CONTD) AND CYCLIC FLUCTUATIONS IN THE TEMPERATURE IN THE STORAGE ROOM. IN SUFFICIENT AIR TIGHT ROOMS EXCHANGE CAN BE ACHIEVED BY FIBRE-FILLED CHANNELS OF VARYING CROSS-SECTIONAL AREA & ALSO CONNECTING THE ROOM WITH A VESSEL CONTAINING CO2.

(…CONTD) : 

(…CONTD) OPERATION USING THIS PRINCIPLE HAS BEEN CARRIED OUT IN SEVERAL SEASONS IN A STORAGE ROOM OF 10 m3 CAPACITY. AIR COMING INTO THE STOREROOM OR BEING RE-CIRCULATED WITHIN THE ROOM MUST PASS THROUGH A MONITORING AND CONTROL SYSTEM.

(…CONTD) : 

(…CONTD) OXYGEN GAS CONTROL: TO DECREASE: PURGING WITH NITROGEN FROM LIQUID NITROGEN THROUGH AN EVAPORATOR FROM A MEMBRANE SYSTEM NITROGEN GENERATOR FROM A MOLECULAR SIEVE SYSTEM NITROGEN GENERATOR CARBON DIOXIDE CONTROL: TO INCREASE: DRY ICE PRESSURIZED GAS CYLINDER TO DECREASE: HYDRATED LIME (USE 0.6 KG OF HYDRATED LIME TO TREAT THE AIR USED TO VENTILATE 100 KG OF FRUIT. AIR CAN BE DIRECTED TO PASS THROUGH A BOX, LOCATED INSIDE OR OUTSIDE THE C.A. STOREROOM).

(…CONTD) : 

(…CONTD) FOR PREVENTING THE BUILDUP OF ETHYLENE, A SIMPLE “SCRUBBER” CAN BE CONSTRUCTED AND ADDED TO THE AIR SUPPLY LINE. ETHYLENE CONTROL: TO DECREASE: POTASSIUM PERMANGANATE ACTIVATED CHARCOAL CATALYTIC OXIDATION

METHODS OF CAS : 

METHODS OF CAS CONSTRUCTING PLASTIC TENTS USING 20 MIL (PVC) SHEETING SUSPENDED OVER TRADITIONAL PALLET RACKS INSIDE A REFRIGERATED COLD STORAGE WAREHOUSE. SEALING HAS BEEN DONE BY CLOSING ZIPPERS ON BOTH SIDES OF THE DOOR AND IMMERSING THE BOTTOM OF THE DOOR AND ADJACENT FLOOR PANEL IN A TROUGH OF WATER. THE TROUGH IS MADE USING A 6 INCH DIAMETER PVC PIPE, WHICH ALSO ALLOWS SUPPLY AND SAMPLING GAS LINES AND TEMPERATURE PROBE WIRING TO PASS INTO THE TENT. ALL SEAMS AND JOINTS OF THE TENTS ARE HEAT-WELDED.

(…CONTD) : 

(…CONTD) CONTROLLED ATMOSPHERE STORAGE OF PALLET LOADS OF PRODUCE IS ALSO POSSIBLE USING A SEMI- PERMANENT SET-UP FOR CREATING A GAS-SEAL. ANY NUMBER OF PALLETS CAN BE ACCOMMODATED INSIDE A PLASTIC TENT MADE USING 7 TO 8 MIL POLYETHYLENE SHEETING. A BETTER GAS BARRIER AT THE FLOOR CAN BE OBTAINED BY LAYING A SHEET OF 4 TO 5 MIL POLYETHYLENE ON THE FLOOR AND COVERING IT WITH WOOD PANELS. THE SEAL IS THEN MADE BY JOINING THE TENT PLASTIC WITH THE FLOOR PLASTIC (USING TAPE).

(….CONTD) : 

(….CONTD) TO REGULATE CO2 LEVELS IN A CA ROOM, ONE OF THE SIMPLEST METHODS IS THE HYDRATED LIME (CALCIUM CARBONATE) CA(OH) 2 “SCRUBBER”. THE SCRUBBER IS CONSTRUCTED USING AN INSULATED AND AIRTIGHT PLYWOOD BOX LOCATED OUTSIDE THE CA ROOM. THE BOX SHOULD CONTAIN ENOUGH LIME FOR THE ENTIRE STORAGE PERIOD, BUT NEW LIME CAN BE ADDED IF CO2 ABSORPTION DROPS.

(…CONTD) : 

(…CONTD) THE CO2 AND HYDRATED LIME REACTS IN A 1:1 RATIO TO FORM LIMESTONE AND WATER. LIME WITH A SMALLER PARTICLE SIZE (FINE MESH) IS MORE EFFICIENT AT REACTING WITH CO2 THAN LIME WITH A COARSE MESH. THE FOLLOWING WILL MAXIMIZE THE EFFECTIVENESS OF YOUR SMALL-SCALE SCRUBBER:

WHAT ARE ITS ADVANTAGES : 

WHAT ARE ITS ADVANTAGES RETARDS SENSCENE AND FURTHUR DETERIORATION OF FRUIT. QUALITY RETAINS OF FOOD MATERIALS. SHELF LIFE INCREASES. RIPENING IS DELAYED AS ETHYLENE IS SCRUBBED FROM THE STORAGE AIR. THE SHELF LIFE OF BANANAS UNDER THESE CONDITIONS IS FOUR TO SIX WEEKS AT AMBIENT TEMPERATURES.

(…CONTD) : 

(…CONTD) CONTROL OF SOME PHYSIOLOGICAL DISORDERS, PATHOGEN, AND/OR INSECTS. PRESERVED SO PROLONG STORAGE. LITTLE OR NO CHEMICAL PRESERVATIVES. ASTHETIC APPEAL

WHAT ARE THE DISAVANTAGES : 

WHAT ARE THE DISAVANTAGES IT IS QUITE EXPENSIVE. TEMP. CONTROL REQUIRED. DIFFERENT GAS COMPOSITION FOR EACH TYPE OF PRODUCT. SPECIAL EQUIPMENT AND OPERATOR TRAINING REQUIRED. ONCE PACK OPENS OR LEAKS THE BENEFITS ARE LOST.

(….CONTD) : 

(….CONTD) INCREASED PACK VOLUME HAS IMPACT ON TREANSPORT AND COST. PRODUCT SAFETY REQUIRED FOR SOME FRUIT.

CONCLUSION : 

CONCLUSION CONTROLLED OR MODIFIED ATMOSPHERE STORAGE SHOULD BE USED AS A SUPPLEMENT TO, AND NOT AS A SUBSTITUTE FOR, PROPER TEMPERATURE AND RELATIVE HUMIDITY MANAGEMENT.

REFERENCES : 

REFERENCES www.encyclopedia.com www.freepatent.com

THANK YOU. : 

THANK YOU.