Walnuts: Possible Defects

Reception

Upon receiving the goods, we recommend that you carry out an inspection of the walnuts as infestation is possible at any stage.

How much to sample?1. Randomly select 2 cartons per pallet2. Upturn to check the corners and bottom for

webbing, shell fragments, etc.3. Sample 500g from each cartons

Typical Walnuts

Light to Amber in colour Soft yet crisp texture Mild sweet flavour

Typical Walnut Colour Walnuts are classified into 4 colours

1. Extra light

2. Light

3. Light/Amber

4. Amber

Darker nuts have higher oil content

Discolouration

Abnormal colouration that covers more than 1/8th of the surface of the kernel and is of a colour in pronounced contrast with the colour of the rest of the kernel [dark blemishes or areas of discolouration] (UNECE)

Can be caused by a fungus (Xanthomonas campestris) that thrives in prolonged wet weather and hull injury

Discoloured Typical Typical

Insect Damage

Visible damage caused by insects or other animal parasites the presence of dead insects or insect debris (UNECE)

Navel Orange worm presents the biggest threat Internal damage and can be difficult to spot early on (inspect a random

sample for signs of internal damage) Serious infestation causes webbing (check corners of containers for this) Look for damage (ie. holes, discolouration) to the nut ‘meat’ Refer to Reception slide for advise on inspecting goods

Mould Damage

Mould filaments that are plainly visible to the naked eye (UNECE)

Mould damage can occur when moisture levels are too high Can lead to growth of aflatoxins caused by Aspergillus Control with proper storage conditions

Dry, cool, air tight containers

Shrivelled Kernels

Kernel which is seriously shrunken, wrinkled and tough (UNECE) Can be caused by an infected tree (ie: anthracnose fungus) Shrivelled kernels are more susceptible to other damages Damage: 1/8th of kernel shrivelled, Serious Damage: 1/4th of kernel

shrivelled, Very Serious Damage: more than 50% of kernel shrivelled (USDA Standards)

Septum The septum develops between the two hemispheres of the walnut and

connects the nut to the shell. Very hard, like the shell Spiky and can easily stick in ones throat

Can be very dangerous, so proper removal is important Can make it to final product as it is of similar colour and can be missed

by laser sorters, therefore, visual inspection can help catch this

Foreign Matter

Any matter or material not usually associated with the product [ie: Adhering Shell, Hull, Dirt, dust] (UNECE)

USDA classified foreign material as serious damage USDA Standards: http://ucfoodsafety.ucdavis.edu/files/175751.pdf

UNECE Standards:

http://www.unece.org/fileadmin/DAM/trade/agr/standard/dry/Standards/DDP02_WalnutKernels_e.pdf

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