TOLERANCE OF SUGAR SNAP PEAS TO MODIFIED ATMOSPHERES WITH HIGH CONCENTRATIONS OF CARBON DIOXIDE

Abstract

Current recommendations for maintaining quality of sugar snap peas in storage include low temperatures, but not modified atmospheres (MA). However, sugar snap peas may be unintentionally exposed to MA when shipped in ‘bag in box’ bulk packaging, or intentionally exposed when used as a component in fresh-cut vegetable trays. The aim of this research was to determine the tolerance of sugar peas to MA. Two experiments were conducted in which sugar snap peas (‘Super Sugar Snap’) were stored at 5°C for up to 21 days in air, 3% O2 + 7, 12 or 18% CO2, or 10% O2 + 12% CO2. Overall, storage in air resulted in the best quality based on subjective (overall visual quality, discoloration, aroma, decay) and objective measurements (sugar, ethanol, acetaldehyde, ammonia). The 3% O2 with 12 or 18% CO2 resulted in visible damage (discoloration) to the peas after 9 to 12 days. This was associated with changes in color (increased darkness, loss of greenness), and substantial increases in ammonia, ethanol and acetaldehyde; all indicative of stress. Quality changes in peas stored in 3% O2 + 7% CO2 or 10% O2 + 12% CO2 were intermediate between the stressful atmospheres and air. Further tests showed that peas (‘Sugar Snap’) maintained good quality at 5°C in air, 3% O2, 3% O2 + 6% CO2 or 10% O2 + 12% CO2 atmospheres for 18 days. Best quality was maintained in air at 0°C for over 21 days. At 5°C for 18 days, some MA combinations provided slight benefit over air storage, and importantly did not result in increased concentrations of stress indicators. If peas have to be in MAP with other fresh-cut vegetables, the 3% O2 + 6% CO2 or 10% O2 + 12% CO2 atmospheres are probably the better options.