Pineapple behaves unexpectedly in a kitchen. Jelly will not set, dairy turns bitter, meat falls apart. A single substance lies behind all three.
What does bromelain do in pineapple?
Bromelain is a protease enzyme occurring naturally in pineapple.
A protease is an enzyme that breaks down protein.
Bromelain cuts the peptide bonds between proteins.
The plant developed it as a defence mechanism.
Its concentration runs highest in the core; the firm central region of the fruit.
It appears in the flesh too but at a lower concentration; that enzyme alone explains why pineapple follows special rules in a kitchen.
| Application | Fresh pineapple | Tinned | Freeze-dried |
|---|---|---|---|
| Is bromelain active | Yes | No | Yes |
| In jelly | Will not set | No trouble | Will not set |
| With dairy | Turns bitter | No trouble | Turns bitter slowly |
| Tenderising meat | Effective | Ineffective | Effective |
| Vitamin C (100 g) | 48 mg | 10-15 mg | 180-220 mg |
| Water | 86% | 80% | 3% |
Why will jelly not set?
Jelly gets made with gelatine.
Gelatine is a protein obtained from collagen.
Its protein chains bind to one another on cooling and form a network, and water gets trapped inside that network.
Bromelain cuts those chains.
No network can form.
The jelly stays liquid.
Jelly with fresh pineapple therefore never sets; the answer is boiling the pineapple first or using the tinned fruit.
Why does it conflict with dairy?
Yoghurt, milk and cream contain casein.
Casein is a protein too.
Bromelain breaks it down.
The peptides released during that breakdown taste bitter.
A smoothie with fresh pineapple turns bitter within minutes.
The same mixture causes no trouble drunk immediately.
Milk desserts with pineapple therefore get made with the tinned fruit; the enzyme is inactive in pineapple that has been heat treated.
How does it tenderise meat?
That is the most useful application of bromelain.
The enzyme breaks down the collagen and muscle fibres in meat.
Tough cuts turn softer.
Pineapple juice joins a marinade.
But the time stays short; meat left longer than thirty minutes takes on a mushy texture.
Two or three tablespoons of pineapple juice suffice per hundred grams of meat; that quantity is the limit tenderising without destroying the texture.
How does heat affect bromelain?
Bromelain is sensitive to heat.
Its activity begins to fall at sixty degrees.
It becomes largely inactive at seventy.
It stops entirely at eighty.
Because tinned pineapple has been pasteurised its enzyme activity is zero.
Tinned pineapple therefore works without trouble in jelly, in milk desserts and in every application.
The same logic applies to cooked dishes; the enzyme has already become ineffective in a baked dish containing pineapple.
What about freeze-dried pineapple?
No heat gets applied in freeze-drying.
That is an advantage for the nutritional values, but the enzyme survives too.
Freeze-dried pineapple contains bromelain.
But because its water sits at three percent the enzyme is immobile; enzymes need water to work.
The effect is limited when eaten dry.
Added to a milk mixture the enzyme finds water and activates; freeze-dried pineapple stirred into yoghurt therefore starts the same bitterness, only more slowly than the fresh fruit.
What nutritional profile does pineapple carry?
Pineapple is rich in vitamin C.
A hundred grams of fresh pineapple carries 48 milligrams, more than half the daily requirement.
It is strong in manganese too: 75 percent of the daily requirement.
Fibre runs two or three grams.
Those values concentrate around fourfold in the freeze-dried form through the loss of water.
A twenty-gram freeze-dried portion equals around a hundred grams of fresh pineapple and meets half the daily requirement for vitamin C on its own.
Does it really help digestion?
That is the most widespread claim and it is partly true.
Because bromelain breaks down proteins it can ease digestion after a heavy protein meal.
But stomach acid inactivates part of the enzyme.
The size of the effect varies from person to person.
Bromelain also gets studied for anti-inflammatory properties.
The bromelain used in supplement form comes at doses far above the quantity in the fruit; a large gap separates the effect of a slice of pineapple from a supplement dose.
How does pineapple get stored?
Whole fresh pineapple keeps three or four days at room temperature.
Two or three days in a fridge once cut.
Tinned pineapple keeps two years unopened; three or four days in a closed container with its own juice once opened.
Freeze-dried pineapple keeps one to two years in an airtight container.
A desiccant sachet gets used; taking up moisture the product first turns sticky and then clumps, and its crisp texture never returns.
Which pairings suit pineapple in a kitchen?
Bromelain aside, pineapple comes forward in particular pairings in terms of taste.
The contrast of salt and sweet is the most classic use; it goes out alongside grilled meat and chicken.
It pairs with coconut; both are tropical and complete one another.
It builds a three-way balance with mint and chilli.
In freeze-dried form it pairs with chocolate; the acidity of the pineapple cuts the bitterness of dark chocolate.
It gets used in cocktails and drinks too.
But pairing with dairy calls for care; combined with yoghurt, fresh or dried pineapple activates the enzyme and the mixture turns bitter within minutes, so it gets eaten the moment it is made.
How does pineapple get chosen?
A few indicators help in choosing a fresh pineapple.
The colour of the skin alone does not suffice; some varieties stay green even when ripe.
The base gets smelled; a ripe pineapple gives a sweet, intense aroma.
Fruit with no smell is unripe, while fruit smelling sour has gone past ripeness.
One of the central leaves gets pulled; where it comes away easily the fruit is ripe.
The fruit should feel heavy in the hand; a pineapple feeling light has lost water.
Soft spots on the skin mean the fruit has begun to rot, and those spots cover a far wider area inside.
