Brazil Nuts: Possible Defects
Brazil Nuts (Bertholletia excelsa) Age and moisture of the nut and temperature
during the process are the variables that have the most influence on the quality of the finished product.
A thermal shock will generate a nut crispy on the outside and soft in the inside, while a gradual increase in the temperature will produce a complete crispy nut.
Texture
Kernels are firm; not
brittle, pliable or
leathery
Colour Light to dark brown
skin, creamy white
meat
The following are possible defects of the Brazil Nut
Brittle The nut breaks in flakes; caused
when the nut suffers a thermal
shock and is over dried.
Dark Centre A clear brown to dark brown dot
appears in the centre of the nut.
Caused by an excessive
dehydration and/or overheating
in the centre of the nut when the
moisture level in the centre is
less than 2%. It occurs when it is
expose to high temperature for
more than 4-6hs.
Discolouration Significant and widespread change of the typical
external or internal colour, from any cause or
source, either intrinsic or extrinsic, including in
particular blackening and the appearance of very
dark colours, but excluding discolouration caused
by a more serious defect such as mould, decay or
damage by pests (UNECE).
Suppliers refer to it as a yellow dot on a side of the
interior meat of the nut. It is caused by bacteria
when the product is stored in poor conditions. A
nut is considered damaged by decolouration when
it penetrates the nut deeper than 1.5mm.
Dirt Adhering Very apparent adhering or
embedded dirt, soil, mud or dust,
producing a smudgy, smeared,
flecked or coated effect that
seriously detracts from the
appearance of the produce.
(UNECE)
It is a mix of pieces of skin and fat
of the nut. Usually it is generated in
the automatic cracking machine.
Fat Diffusion Nuts that present an oily-translucent area
bigger than the 20%.
This defect is caused mainly in the
autoclave. High pressure and temperature
produce a breakage of the cells allowing the
oil within to spread out.
If the nut enters the autoclave with a
moisture level higher than 17%, the resulted
nut will be a “crystalline” nut.
This is a characteristic inherent to chipped,
broken and flaked product so it is not
considered to be a defect in those products.
Insect Damage
Visible damage or
contamination caused by
insects, mites, rodents or
other animal pests,
including the presence of
dead insects and/or mites
and their debris or excreta.
Mould Damage When the nut is in the forest and
the moisture level is high, the
conditions for mould growth are
ideal. The mould attacks the in
shell nut entering into the shell
and then nut. If the fungus is one
of the Aspergillus, it will
produce the aflatoxins
contaminating the nut.
Reddish Colour Not considered a defect, some
nuts present a reddish colour due
to an underdevelopment of the
skin.
Other situations that could
generate a reddish nut is when
the in-shell nut stays wet in the
forest, the skin stuck to the
kernel will colour the nut giving
a different tonality.
Rancidity Kernels stale to the taste
UNECE defines it as an oxidation of lipids or free fatty acid
production giving a characteristic disagreeable flavour; an oily
appearance of the flesh does not necessarily indicate a rancid
condition.
AFI specification uses a limit for FFA and PV as Rancidity
Indicators on whole nuts.
Rotten Nut/ Decay Significant decomposition caused by the
action of micro organisms or other
biological processes.
This is normally accompanied by
changes in texture (soft or watery
appearance) and/or changes in colour
(from brownish to blackening).
Usually in shell rotten nuts can be
differentiated by the colour of the shell.
When the rotten nuts are cut for control
at intake
Adhering Shell
If in the autoclave the nut
does not expand and
shrink properly the shell
can stay adhered to the
nut. shell
Shrivelled
Nuts that present a rough texture
or is abnormally wrinkled in
more than 25 % of the kernel
This difference can be caused
by insufficient development of
the kernel or excessive
dehydration
Chía Nuts with a dark dot are considered
to be at the starting point of
rottenness. This could be generated
by micro organisms. One of which
could be the Aspergillus spp.,
responsible of aflatoxins occurrence
in the nut.
Aflatoxins will be fluorescent under
UV light in different colours
depending on the type of toxins.
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