Cracked it
Question: I am unable to crack a Brazil nut to extract the contents in
suitably sized edible pieces. The kernel shatters and I find that the only way
that I can retrieve the crumbs is on the tip of a wet finger.
How do the processors of Brazil nuts actually get them out of their
shells?
Answer: The industrial process for shelling Brazil nuts involves soaking them
in water for 24 hours, then immersing them in boiling water for five minutes to
soften the shell. The shells can then be removed from the nut quite easily by
hand and the nut will need to be dried. If a Brazil nut is shelled in this way
it is important to eat it soon, as the boiling 鈥渒ills鈥� it.
Advertisement
Jason Hiscock
Walton-on-Thames, Surrey
Answer: The answer to cracking a Brazil nut, or any other hard nut, is to use
a pair of Mole grips. Every engineer has a pair of these grips and they are very
handy at Christmas.
After some practice adjusting the grip jaws, only the minimum force need be
applied to split the shell without bursting it. Cracking similar sized nuts in
batches, such as a bag of Brazils or a handful of walnuts, makes the process
faster.
Because of their triangular cross-section, may need to be turned by 120掳
and have similar pressure applied.
Richard Hames
Datchet, Berkshire
Answer: The cross section of a Brazil nut is roughly an equilateral triangle,
with a slightly shorter base. But if you look inside the nut, you will find that
while the shell is usually attached across this base, it tends to be free nearer
the apex.
Most people trying crack the nut the easy way鈥攂y squeezing the crackers
across the base, which is the shortest side. This transfers all the force
directly to the nut itself鈥攈ence the shattered mess. Instead, apply the
crackers across one of the sides, holding the nut between the apex and one of
the lower edges. In most cases, the side wall will split neatly, leaving the nut
whole and unshattered. If the other side wall is broken the same way, you will
get more whole nuts than broken ones.
Doug Cross
Honiton, Devon
Answer: In Australia we grow the extremely hard macadamia nuts.
In Queensland, at an orchard where these nuts are grown, you can buy a
hand-held vice of simple design, which cracks the nuts gradually as it is
tightened.
Any reader who is interested in a more detailed description of this
nutcracker, which works equally well with Brazil nuts, can get in touch with me
by e-mail at selig@axis.jeack.com.au
Richard Seligman
Melbourne, Victoria
The whole Brazil nuts are placed into industrial pressure cookers called
autoclaves and boiled until the shell softens slightly and expands, leaving the
nut loose inside. Today most are machine cracked. They are fed between steel
rollers with a gap slightly smaller than the nut itself and set at tolerances so
just enough pressure is applied to crack the shell. The unscathed kernel then
falls free.
Smaller, older companies may crack their nuts using a vice-like implement,
but this is not as sensitive and results in more wastage鈥擡d (With thanks
to the chocolate maker Thornton鈥檚)
Wax lyrical
Question: Some fruits are coated with a waxy compound to preserve them while
they are being transported. Which fruits are so treated? Is there any reason why
some fruits cannot be treated like this? What substance is used and is it in any
way harmful to humans?
Does simply washing the fruit in warm water remove the coating, or is a
detergent necessary too?
Answer: Since the 1930s, growers have applied a shine to fresh fruits. It is
usual to wash fruits when they are harvested, to remove chemical residues and
field dirt. This may wash off the fruit鈥檚 natural wax, making it more likely to
shrivel and decay. So waxes are sprayed on during grading and packing to replace
coatings lost in processing and help maintain quality. Certain wax coatings also
give the fruit an attractive shine and protect against injuries during
storage.
A wide range of fruits is waxed: in the US there are more than 25 types of
fruit and vegetables which may be legally coated, including most citrus fruits
and many apple varieties, pears, avocados, aubergines and pineapples.
In the European Union, wax coatings are made from a variety of compounds. The
most common ingredients are shellac, carnauba, candelilla wax, beeswax and
oxidised polyethylene, all of which have various other food uses. A number of
waxes containing mineral oils were once used, but these are no longer
permitted.
Alternative coatings based on sucrose ester and cellulose ingredients are
used on certain fruits. These function not so much as glazing agents, but rather
as coatings which are designed to slow respiration, delay ripening and protect
against injury from chilling.
Simon Matthews
Great Shefford, Berkshire
Answer: To poison yourself with the waxes on fruit, you probably would have
to eat the raw waxing material by the kilogram until it absorbed a great many of
your fat-soluble vitamins or obstructed your gut. However, it is conceivable the
wax would sequester certain insecticide residues, carrying them harmlessly
through the gut.
Wax is effectively inert in the gut and if some trace does break down so that
you absorb it, you would probably metabolise it as you would any other food.
Many foods, especially plants, naturally contain a considerable range of waxy
substances, such as true waxes and sterols, most of which pass through the human
system without much effect, good or bad.
In fact, in some South African fish, oily waxes replace fats as a major
energy storage medium in animal plankton and some fish. Humans cannot assimilate
these waxes, so the oily substance lubricates the gut, with laxative effect. So
such fish, though tasty, should avoided. Watch out for names such as 鈥渂utter
fish鈥� and 鈥渒asterolie snoek鈥� (literally 鈥渃astor oil barracuda鈥�).
Jon Richfield
Dennesig, South Africa
Answer: This practice is a nuisance for vegans as sometimes the glazes, such
as beeswax or shellac, come from animals. I don鈥檛 know if their use harms humans
but it exploits animals.
Lesley Dove
Harrow, Middlesex
This week鈥檚 question
Red hot: What causes the colours that form on a clean iron or steel surface
after it has been heated and cooled for tempering? The colours range from yellow
when the metal was heated to about 200 掳C, through gold, brown, purple, blue
and finally black when heated to about 600 掳C. And because the oxidised blue
or purple finishes on steel mechanisms have often survived unmarked in clocks
from the last century, what is the physical nature of this transparent and very
durable coloured layer?
John Rowland
Allestree, Derby