Abstract:
The degree of ripeness of many climacteric fruits, such as avocado, can be
correlated with fleshfirmness and other rheological properties. However, there
remains a paucity of information on not only thepostharvest changes in texture
of avocado fruit from different origins, but also on the spatial variation in
texturewithin individual fruit. In addition, the relationship between changes in
texture and lipid profile of fruit tissueduring postharvest ripening is
unknown.The aim of the present study was to assess and discriminate between
avocado cv. Hass fruit from threedifferent origins (viz. Spain, Peru and Chile)
on the basis of temporal and spatial changes in both texture andfatty acid
profiles of fruit flesh. Texture of different horizontally-cut slices from
individual fruit within aconsignment was measured during ripening using a
previously unreported technique. Maximum load, elasticityand viscosity of fruit
tissue was measured using an Instron 5542 universal testing machine fitted with
either a500 N or 5 N load cell. The same fruit slice was immediately snap-frozen
in liquid nitrogen and freeze-driedprior to subsequent extraction,
identification and determination of fatty acid methyl esters (FAME) profiles
usinggas chromatography coupled to flame ionization detection (GC-FID). The
results were used to differentiate avocado fruit into definable groups using
partial least squares discriminant analysis. Significant differences inmaximum
load, elasticity, viscosity were found in avocado fruit flesh during ripening,
and between origins andto a lesser extent between different locations within the
fruit. Lipid profiles showed dissimilar compositionaccording to origin and
changed slightly from apex to base. The textural changes and lipid profile in
avocadofruit is therefore related to origin and the spatial variation within
individual fruit.
