MA, CA and MC

MA, CA and MC

1. all about reducing respiration and controlling water loss

   • CA - equipment adjusts gases
   • MA - product adjusts gases
     • if permeability is too low will cause anaerobic conditions
       • tend to 0% O2

2. reduce O2 to 10%

   • too low leads to anaerobic conditions
     • can cause botulinum

3. Increase CO2 by 1-3%

   • apples damaged at >3%
   • high CO2 can kill off pests

4. CO2 and water causes carbolic acid

5. can cause physiological disorders

   • browning
   • internal disorders
   • off flavours
   • increased rots
   • irregular ripening

6. one O2/CO2 mix doesn't fit all, crop dependant

   • root veg tolerates lower O2 than citrus
   • strawberrys tolerate more CO2 than tomatoes

7. CA container technology

8. film permeability matches resp rate

   • equilibrium
   • slowing of resp
   • freshness preserved
   • extension of shelf life

9. O2 reduces and CO2 increases

   • Nobile et al 2006

10. films are temperature dependant

    • OTR rate at a certain temp
      • Oxygen transmission rate

11. Gas flushing

    • speed up time to equilibrium
      • with N - reduces O2%
        • with optimum mix of CO2, O2 and N2

12. MC

    • grain wants to stay dry
    • perishables want to have high MC
      • increase RH
      • reduce air movement
        • need fans to reduce hot spots
      • >90%
    • condensation increases rotting/splitting
    • reduce temperature fluctuations
      • reduce water loss/condensation