Abstract
Southern Africa has a wide range of edible fruits, which can be useful in alleviating
food and nutritional insecurity. However, many of these fruits are underutilized. An
example of such underutilized fruits is that of Strychnos madagascariensis. Strychnos
madagascariensis is an underutilized South African fruit bearing tree, with the pulp
being the primary consumable component, however, the seeds hold the potential as a
food source due to their high nutrient composition. The aim of this research was to
evaluate changes in the nutritional composition of S. madagascariensis seeds across
four progressive ripening stages (stage 1 to 4) to identify parameters that may be used
for maturity indexing. The fruit of S. madagascariensis were collected directly from the
tree at four stages of ripeness, starting from completely green (unripe) fruits to ripe
fruits that had begun turning brown. Parameters such as fruit and seed physical
properties, seed nutritional composition, seed flour functional properties, and seed flour
pasting properties were evaluated. Principal component analysis (PCA) was usedto
identify parameters which were capable of being distinguished amongst the four
ripeningstages. It was found that the seeds at stage 1 (unripe fruit) of ripeness held
greater nutritional compositions, prominently observed in the fiber, protein, potassium,
and manganese content (80.02%; 10.29%; 0.90; and 0.01g/ 100g, respectively).
Functionalproperties varied throughout each ripening stage. However, stage 3 (ripe
fruit) and 4 (over-ripe fruit) had better functional properties (such as foaming capacity
and stabilityand swelling power). Thus, the seed flour of fruits collected at these stages
show a greater potential for food product development in comparison to stages 1 and
2 (partially ripe fruit). Both the flour and paste colour and functional properties were
able to distinguish between all four ripening stages. Lastly, the fruit rind colour
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only created two separations, in which stages 1 and 2 were grouped together and
stages 3 and 4 were grouped together. Thus, a maturity index, targeting the seeds of
S. madagascariensis,may be developed by combining two ormore of these parameter
groupings, such as flour colour and rind colour, potassium and magnesium contents.