Extending shelf-life of minimally processed carrots

The effect of mild heat pre-treatments and different atmosphere composition on quality of minimally processed carrots was evaluated. In a first trial whole carrots were subjected to different mild heat pre treatments (MHPT) by dipping in different controlled temperature water baths for different periods. A Central Composite Rotatable Design (CCRD) was used as experimental design. One day after MUPT carrots were peeled, sliced and packed. Samples were evaluated to cut surface discoloration, firmness, soluble solids content (SSC) and pH along a storage period of 15 day. To the results response surfaces were adjusted. The best conditions found (pre treatment at 40 degrees C/60 minutes) was used on a second trial conducted using three different packaging atmosphere: passive mode (20.9% O-2 - 0.03% CO2) and active mode (1% O-2 - 10% CO2; 80% O-2 - 0.1% CO2). A low-density co-polymer of polyethylene and vinyl chloride was the used film. Samples packaging in the same conditions but not subjected to mild heat pre treatment were used as control. Pretreated samples showed an increase in firmness from an initial value of 98.10 N to 137.34 N in all tested packaging atmosphere. However the atmosphere that produced an increase in extending shelf life was the one presenting low oxygen content. In those conditions dehydration was avoided and the firmness along a storage period of about 10 days was preserved.