Preliminary studies on the effects of post harvest temperatures on the ripening of pepino fruit : Project submitted in partial fulfilment of the requirements of the degree of Bachelor of Horticultural Science (Honours) at Lincoln College, University of Canterbury

Abstract

Little is known about the post harvest physiology or storage requirements of Solanum muricatum Ait.

To evaluate the pepino's ripening behaviour at different storage temperatures,fruit were harvested according to three colour based maturity levels and blocked on size. The fruit were placed at 10 °C - vapour pressure deficit 0.061 kPa, 20 °C - vapour pressure deficit 0.647 kPa and 30°C - vapour pressure deficit 2.12 kPa.

During a four week storage period determinations of background colour development, weight, diameter and length loss of the fruit, flesh firmness, soluble solids and total titratable acidity were made.

The most dramatic change in fruit characteristics occurred in the 0 to 14 day storage period at 30°C. During this period a highly significant colour development and reduction in fruit acidity occurred, along with a loss in soluble solids and flesh firmness that exceeded all other stored fruit.

A similar pattern of change was recorded in fruit stored at 20°c between days 14 to 21. Fruit stored at 10°C demonstrated a linear increase in colour and decrease in soluble solids. The trends in acidity and flesh firmness of fruit stored at the lower temperatures were not apparent until 21 to 28 days after harvest.

As temperature increased the trends in ripening characteristics developed earlier in storage. Initial maturity of the fruit and vapour pressure deficit of the storage atmosphere were also determining factors. At 10°C the fruit showed slower, but more natural ripening when compared with the 30°C stored fruit which appeared to demonstrate enhanced senescence.

Flavour and textural components need to be investigated as off-flavoured fruit appeared to develop with high temperature storage.

Combined temperature treatments may be the solution in ripening pepino fruit to maturity.