Harvest and post-harvest conditions influencing macauba (Acrocomia aculeata) oil quality attributes

Abstract

Macauba (Acrocomia aculeata), also known as macauba palm, is a good source of vegetable oil in tropical America. Its fruits are highly suitable for biodiesel production owing to the high quantity and quality of its oil. However, commercial exploitation of this species remains insufficient. Forms of harvesting, the storage period, and the use of chemicals for the postharvest preservation of macauba fruits and their effects on the associated microbiota were investigated. Mature fruits were collected only once from the mother tree and separated in two groups, a group of fruits not exposed to the ground surface (0 days) and a larger group of fruits that was placed in contact with the soil surface for 7, 14, and 21 days, to allow infestation of soil-borne microorganisms. Then the fruits were treated with 3 doses of fungicide fungicide (0, 0.2, and 0.4% v/v) and storage at room temperature during 0, 10, 20, 30 and 40 days. Hence the experiment was set in a randomized block design with four replications in a factorial Scheme 4 × 3 × 5 (period of ground surface contact, doses of fungicide and period of storage). The mesocarp oil content (OC), free fatty acids, and oxidative stability of the oil were evaluated, and the presence of microorganisms in the mesocarp and epicarp of the macauba fruits was quantified. Fungicide was found to be effective in maintaining low oil acidity of fruits unexposed to the soil surface for up to 20 days of storage and for maintaining oil oxidative stability. Regardless of the fungicide dose applied, an increase in the OC was noted for all harvest times during the first 10 days of storage. Therefore, for biodiesel production, it is recommended that the fruits should be harvested when in pre-absciscion stage (directly from the mother tree) or collected from the ground after no more than 7 days after abscission. In both cases, the fruits must be pre-treated with fungicide if storage is intended.