This document provides information on possible defects in walnuts, including guidelines for inspecting shipments for infestation and descriptions of typical and atypical qualities. Key defects discussed are discoloration, insect damage, mould damage, shrivelled kernels, septum presence, and foreign matter contamination. Proper inspection and storage are emphasized to identify defects and prevent further issues.

1. Walnuts: Possible Defects

2. 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 pallet
2. Upturn to check the corners and bottom for
webbing, shell fragments, etc.
3. Sample 500g from each cartons

3. Typical Walnuts
 Light to Amber in colour
 Soft yet crisp texture
 Mild sweet flavour

4. 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

5. 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

6. 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

7. 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

8. 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)

9. 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

10. 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

11. Be Sure to Take A Look at
Our Other Product
Overviews by Clicking on the
Product Tabs!