The use of canola oil coatings to extend the storage life of Nashi pears

Abstract

Nashi cv. Nijisseiki was coated with canola oil before storage at 0°C over 3 consecutive seasons. This resulted in greater retention of green colour, even after only 8 weeks of storage. This effect continued throughout the 40-week storage period and after 1 week at 20°C. Physiological disorders were generally low. The internal atmosphere was measured during storage at 0°C. The mean carbon dioxide levels for control and treated fruit were approximately 0.5 and 1.9%, and oxygen levels were 20 and 13%, respectively. The mean ethylene levels were approximately 5 and 30 μL/L, respectively. Thus, in oiled fruit, increased carbon dioxide levels may have overcome the effects of increased levels of ethylene. When fruit was transferred to 20°C, carbon dioxide and ethylene levels rose and oxygen levels fell but no damage was evident at the lower oil concentrations. Non-oiled fruit was then stored in polyethylene bags with or without a carbon dioxide absorbent (Calcium hydroxide) and an ethylene absorbent (Purafil). Fruit stored with the former became as yellow as the control fruit in air, whilst fruit with Purafil remained greener than fruit held in bags alone. When the absorbents were used together, much of the fruits’ green colour was lost. Carbon dioxide levels therefore appear to be most important for the retention of green colour, and generally improve storage life. Ethylene removal further improves the retention of green colour in the Nijisseiki cultivar. A storage life of at least 40 weeks at 0°C was achieved with fruit from several sources in 3 seasons. Preliminary recommendations for small-scale hand applications are 1 or 2 drops per 240 g fruit. Commercial trials could involve dipping or spraying with 1–2% oil emulsified with Tween 80.