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Storage of apples and pears

ULO cooling

ULO is the acronym for Ultra Low Oxygen. ULO-refrigeration systems operate with a low concentration of oxygen. Therefore your produce is able to be stored longer giving you control over the quality of the cooled produce. IVL is specialized in the storage of apples and pears. If your produce requires a longer storage life, cooling with ULO is an ideal solution. 

IVL Commercial Refrigeration B.V. delivers solutions for apple and pear storage including but not limited to, the following systems:

  • Direct expansion systems with low GWP (the refrigerant R-134A or R-407F among others)
  • Indirect cooling systems developed (Temper, Thermera, glycol among others)
  • Ammonia circulation systems
  • CO2 refrigeration systems, both sub- and transcritical

Storage of apples

About 25 million tonnes of apples are produced globally, principally in the earth’s temperate zones. The right moment of harvesting is extremely important for what can still be done with the apples after the harvest. To store apples for a long time, they must be harvested before the ripening process has begun. Harvesting too early affects the quality. The fruits will be small, hard green, have little red blush and they will be sensitive to storage defects such as scald and pits. When apples are harvested too late, they can become mealy. The fruits in that case will be soft and very sensitive, so the storage options are limited. Optimum storage conditions of apples depend on variety, harvest time, region, orchard location, etc.

CA storage of apples

Apples generally respond very well to lowering O2 and increasing CO2 (CA storage). Depending on the variety, the condition remains good at temperatures between 0° and 5° C. To limit loss of moisture as much as possible, we recommend storing apples at high air humidity, between 90 and 95%.

ULO storage of apples

Refrigerated apples usually produce little ethylene as long as they do not ripen. However, they are very sensitive to ethylene at that time, which initiates ripening. Ethylene production is kept low by storing at a very low oxygen percentage (ULO storage). It is important that the sensitivity of apples to ethylene is zero in ULO conditions.

Storage of pears

About 16 million tonnes of pears are produced worldwide, which is 4.2% of total global fruit production. Pears are chiefly produced in the earth’s mild climates. Pear trees do not do well on cold nights during the flowering period. The moment of harvesting is extremely important for what can still be done with the pears after the harvest. To store pears for a long time, they must be harvested before the ripening process has begun. Harvesting pears too early goes at the expense of the weight since the fruits are still growing in diameter, particularly in the last phase. Harvesting too early also affects quality, as there is a chance the pears can no longer ripen. Another risk for pears is that they become worthless when they lose too much moisture. The pears then become soft around the stem especially (soft necks). Pears must not ripen on the trees either, as they become grainy and mealy.

CA/ULO storage of pears

Pears can be stored in CA and ULO refrigerators. Depending on the variety, their condition remains good at temperatures between -1° and 0° C. To limit loss of moisture as much as possible, we recommend storing pears at high air humidity, between 90 and 95%.

CA storage of pears

Pears generally respond very well to lowering O2, but much less to increasing CO2. Increasing CO2 in combination with a late harvest can be a significant factor in causing defects in the fruit. This is why we recommend keeping the CO2 below 0.7% for most pear varieties.

ULO storage of pears

Pears usually produce very little ethylene as long as they do not ripen. However, they are very sensitive to ethylene in the period before ripening, as this can initiate ripening. In ULO storage conditions, the ethylene production is reduced drastically, thus preventing premature ripening.