Pineapple - Crop Post-Harvest: Science and Technology - page 144

Table 7.1 Composition of Pineapple Fruit.

Amount per 100 g
edible portion

Amount per 100 g
edible portion Nutrient Nutrient

Water 80-86 g Ascorbic acid 10.00 mg

Energy 218 KJ Vitamin B12 0.09 mg

Protein 0.2 g Vitamin B6 50 IU

Lipid 0.2 g Vitamin A, IU 53 IU

Carbohydrate 13.5 g Vitamin A, RE 1.0

Acids 0.5-2 g α Tocopherol 0.16 mg

Total sugars 8 g Riboflavin 0.4 mg

Fibre 0.5 g Folate (Total) 11 mcg

Ash 0.3 g Thiamin 0.9 mg

Calcium 18 mg Cryptoxanthene 0 mg

Iron 0.3 mg Niacin 0.036 mg

Magnesium 12 mg Pantothenic acid 0.42 mg

Phosphorus 12 mg Potassium 98 mg

α Carotene 31 mcg Brix 10.8-17.5

Sodium 1 mg Titratable acidity 0.6-1.62

Source: Dull (1971) and Wenkam (1990).

(fruity), ethyl 2-methylbutanoate (fruity) followed by methyl
2-methylbutanoate (fruity, apple-like) and 1-(E,Z)-3,5-
undecatriene (fresh, pineapple-like) (Tokitomo et al . 2005).
The proteolytic enzyme, bromelain, obtained from the
juice or mature plant stem (Nakasone & Paull 1998) is used
for tenderizing meat and chill proofing beer, is added to
gelatine to increase its solubility for drinking and has
been used for stabilizing latex paints and in the leather
tanning process. In modern therapy, bromelain is used as a
digestive and for its anti-inflammatory action after surgery
(Nakasone & Paull 1998). Bromelain, is believed to cause
soreness and discomfort of the mouth when excessive amount
of fresh pineapple is consumed. The presence of bromelain
in pineapple juice also prevents gelatinization if the juice is
used as an ingredient for gelatin. Therefore, commercial
pineapple juice has to be pasteurized to inactivate the
enzyme. Bromelain FA2, the main proteinase component of
the juice of pineapple fruit, has been purified and
characterized, the molecular weight being 31 000 Daltons
and the isoelectric point pH 4.6 (Yamada et al . 1976).

only very small flowers. Ethylene is believed to be the
chemical which causes natural initiation of flowering.
Plants can be artificially induced to flower at any time
by applying ethylene-producing chemicals (Sinclair
1993). In pineapple, and other bromeliads, it has been
proposed that flowering is triggered by a small burst of
ethylene production in the meristem in response to
environmental cues (Trusov & Botella 2006). Flowering
dynamics studies revealed significant differences in
flowering behaviour, with transgenic plants that
exhibited the silencing ACACS2 (1-amino-cyclopropane-
1-carboxylate synthase) gene showing a marked delay
in flowering when compared with nonsilenced transgenic
plants and control nontransformed plants. It appears
that the ACACS2 gene is one of the key contributors
towards triggering 'natural flowering' in mature
pineapples under commercial field conditions (Trusov &
Botella 2006).
It takes approximately four months from the end of the
last open flower to fruit maturity and the total time required
from flower initiation to harvest is between six and seven
months (Nakasone & Paull 1998). During maturation, the
fruit size, weight, soluble solids and acidity in the flesh are
increased. During ripening, the shell of the pineapple loses
chlorophyll rapidly, starting at the fruit base, the pulp
soluble solids increase dramatically and the fruit attains the
maximum eating quality.

FRUIT DEVELOPMENT AND PHYSIOLOGY

Fruit development
Pineapples can initiate flowers only after reaching
a minimum weight (about 500 g for Smooth Cayenne).
However, plants at this minimum weight will produce