Fruit quality characterisation of papaya germplasm in uganda
Abstract
Cultivated papaya, Carica papaya L., is the most economically important fruit in the Caricaceae
Family. Both female and hermaphrodite papaya plants are commercially useful for fruit
production, while the males are solely used as a pollen source. Papaya fruit is also a potential
source of proteolytic enzymes like papain and chymopapain. Nineteen accessions of papaya
namely 16/5, 16/15, 16/16, 16/20, 16/1, 16/17 R+L (R), 16/18 R+L (L), 16/19, 16/6, 16/10, 16/3,
16/4, 18/10, 18/5, 18/25, 18/1, 18/4, 18/16 and 18/20 were evaluated. Fully mature hard papaya
fruits of the selected were harvested at the appearance of yellow stripes indicating maturity of the
fruit which were kept at the counter for a period of 7days for them to ripen and then were evaluated
for the different parameters. The plant materials were obtained from locally available papaya
varieties and landraces from all over Uganda. The collection was undertaken over the period of
2016 and 2018. The papaya germplasm collected consisted a total of 35 papaya plants, among
these, some were males and a few had died off.
Data was collected on the aforementioned accessions from the germplasm for Physical parameters
of Fruit weight, External fruit firmness, Internal fruit firmness, Pulp thickness, Presence of hard
lump pulp, Shelf life, Percentage dry matter (DM), Pulp colour, pH and Total Titratable Acidity
(TTA). Accession 16/15 was recorded to have the highest average fruit weight of 3876g. Accession
16/16 exhibited an exceptionally high external firmness value of 9.73Kgf after 7days from the
time of harvest. Accession 16/5 (2.23Kgf) showed the lowest external firmness. The highest
internal fruit firmness recorded was 1.35Kgf (16/16) and the lowest was 0.20Kgf (16/6). Shelf life
was determined by keeping the samples in the open at room temperature (at the counter) and
observations made at 2 days’ interval until they are unfit for consumption and accession 18/16 and
16/16 recorded to stay longer of than all the other accessions (i.e. 12.7 and 12.3 days respectively).
16/5 and 16/6 stayed for the least number of days (i.e. 7.7days on average each) from physiological
maturity. The highest average percentage DM value recorded was 19.2% exhibited by accession
18/16, while the lowest recorded was 14.4% exhibited by 18/25. The average pH for the different
accessions ranged from 5.80 to 4.43 with the grand average pH of 4.93. Accession 16/18 R+L (L)
had the lowest TTA of 0.030% while the highest (0.079%) was recorded in accession 18/4.
Accessions 16/20, 16/4 and 18/10 exhibited the highest severity of hard lump pulp, accessions
16/5, 16/15 and 16/10 recoded no hard lump pulp. Pulp colour names were determined using the
Royal Horticultural Society Colour Chart (RHS, 2015) (Table 2). Pulp colour ranged from yellow
to red.