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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