INTRODUCTION
SAMAC Handlers are guided by the quality specifications proposed by the International Nut and Dried Fruit Council (INC).
SAMAC HANDLERS AGREED MINIMUM STANDARD FOR MACADAMIA KERNEL
SAMAC Handlers adhere to a minimum standard for macadamia kernel, based on a combination of specifications adapted from the INC, UNECE 22 and 23 and internal minimum standards. The following standards have been agreed to by all SAMAC Handlers:
| PARAMETERS | PROPOSED STANDARD |
| Moisture content | Maximum 1.5% with a tolerance of 0.2% |
| Peroxide value | Max 3.5% meq/kg |
| Free fatty acids | Max 0.5% |
| Aflatoxin total | Max 4 ppb |
| Aflatoxin B1 | Max 2 ppb |
| Chemical residues | As per importing country’s food standards |
| Total plate count | <30,000 cfu/g |
| Yeast and moulds | <30,000 cfu/g |
| Escherichia coli | Less than 3/g (MPN method); Not detected (triplicate tube method); Less than 3 cfu/g (ISO 16649-2) |
| Salmonella | None detected in 25g ( ISO 6579 or BAM method) |
| Coliforms | < 350 cfu/g |
| Reject Defects (Insect damage, discoloration, shrivelled/immature) | Max 1.5% |
| Insect infestation | None |
| Kernel Colour | Uniform, normal, natural cream colour |
| Kernel Appearance | Free from surface oil |
| Flavour and Odour | No off flavours or odours |
| Kernel Dust | The UNECE Standard DDP-23 specification: foreign matter, shells and dust: 0.25% by weight |
| Foreign material | None |
| Loose shell pieces | The UNECE Standard DDP-23 specification: foreign matter, shells and dust: 0.25% by weight |
| Impacted Shell | The UNECE Standard DDP-23 specification: foreign matter, shells and dust: 0.25% by weight |
| Bulk packaging | Packaging material should be food grade; Flushed with N2 / CO2 so that residual oxygen is less than 2% |
| Bulk packaging material transmission rates | At 25°C and 75% RH and 1 atm: Water vapour less than 0.1 cc/m2 ; Oxygen less than 0.1 cc/m2 |
| Retail packaging | ‘Nitrogen or food grade CO2 flushed and residual oxygen is less than 2% |
| SIZING | |
| Style 0 | Greater than 20 mm with min 95% wholes |
| Style 1 | 16-21 mm with 90% wholes |
| Style S1 | 13 – 17 mm with 95% wholes |
| Style 2 | Greater than 13 mm with min 50% wholes and maximum 50% halves and large pieces ranging in size from 13 mm upwards |
| Style 3 | Pieces greater than 13 mm with min 15% wholes |
| Style 4L | Pieces greater than 13 mm with min 80% halves |
| Style 4S | Pieces 9-15 mm with min 50% halves |
| Style 5 | 8-14mm pieces (Minimum 80%) |
| Style 6 | 5-9 mm chips and pieces (min 80%) |
| Style 7 | 3-6 mm chips and pieces (min 70%) |
| Style 8 | Pieces smaller than 3 mm (min 70%) |
| GRADES | |
| Commercial grade | Kernel containing dicolouration, onion ring and 791 spot which does not affect the taste of the kernel. To be used in food ingredients |
| Industrial grade | Kernel with defects such as insect damage which are not suited for human consumption – only to be used for oil processing and cosmetic products etc |
CRACKOUT DETERMINATION
STORAGE OF VACUUM PACKED RAW MACADAMIA KERNEL
Vacuum packed raw macadamia kernel should be stored in a cool (15°C to 25°C), dry and well ventilated area. Stored under these conditions, raw macadamia kernel which conformed to all the quality specifications at packing, will maintain this quality for 16 to 18 months without any serious quality deterioration. This length of time of quality preservation is of course only achieved if the correct vacuum pouch material, with the oxygen and water vapour transmission rate properties as described below is used:
Gas flushed (nitrogen or carbon dioxide) vacuum packed macadamias at 1.5% or less MC%, have been shown to have a storage/shelf life of 12 to 18 months, at ambient temperature (up to 38°C). PROVIDED that the materials used for vacuum pouches meet the following oxygen and water vapour transmission rates:
Oxygen:- maximum 0.1cc/m2/24 hours @ 25°C, 75% RH and 1 atmosphere pressure.
Water Vapour:- maximum 0.1 g/m2/24 hours @ 25°C, 75% RH and 1 atmosphere pressure
These maximum transmission rates can be provided for by the following composition of pouch material:
| Biaxially oriented (BO) nylon | 15 micron |
| Aluminium foil | 9 micron |
| LLD polyethylene | 96 micron |
| TOTAL | 120 micron |
Which most processors have agreed to standardise on from the 1998 season onwards
Most processors have also agreed to work towards standardising on a nett weight per carton of 25lbs (11.34kg) of kernel, since this appears to be the carton weight most commonly used in the international macadamia market. The dimensions of the standardised pouch of composition as mentioned above are:-
550 mm x 610 mm, with the pouch opening on the 610 mm dimension.
This size of pouch will adequately hold 25lb (11.34 kg) of macadamia kernel of all styles, once vacuum sealed for insertion into the carton.
On removal from the vacuum pouch, raw macadamia kernel will maintain freshness, if placed in an airtight container in a refrigerator, for at least 2 months. If, after removal from the vacuum pouch, raw macadamia kernel is left unsealed, or even kept in a thin polyethylene or other plastic bag, at ambient conditions, quality deterioration will be very fast and off odours and flavours will begin to be detected after only 3 to 4 weeks, after which rancidity sets in, making for a very bad macadamia eating experience.
Work done by Cavaletto et al (1966) showed that raw macadamia kernel stored at 1.4% moisture in vacuum packed pouches, showed excellent stability at all storage temperatures for 16 months. The storage temperatures compared in this study were 35°F (5.5°C), ambient and 100°F (37.5°C) in both light and dark conditions. Stability measures were:
Raw kernel flavour
Raw kernel total sugar content
Raw kernel reducing sugar content
Raw kernel free fatty acids
It was only at higher moisture contents of kernel vacuum packed and stored in this experiment, that quality deterioration as measured by the abovementioned parameters, was detected over time. Since all South African product is vacuum packed at kernel moisture contents <1.5%, it would appear from this work that even temperatures up to 37.5°C do not bring about quality deterioration over 16 months.
Yet another study, conducted by Bowden and Reeves (undated) in Australia, showed that as long as raw kernel was sealed (either vacuum packed or non-vacuum packed) in pouches of the correct material meeting the oxygen and water vapour transmission rates as defined in an earlier paragraph, it could be stored for up to 8 months under Brisbane ambient conditions with virtually no deterioration in quality. In this instance, the quality parameters measured were:-
Raw kernel flavour and odour (6 member panel)
Roasted kernel colour, flavour and texture (20 member panel)
Raw kernel peroxide value and free fatty acids
Raw kernel total sugar and reducing sugar contents
Despite all of this experimental evidence, quality preservation can be ensured with confidence if the recommended 15°C to 25°C storage temperatures can be maintained in a well ventilated dry storage area.
Reference:
Cavaletto, C., Dela Cruz, A., Ross E. and Yamanoto, HY. 1966 Factors Affecting Macadamia Nut Stability. Food Technology August 1966
Bowden, RP and Reeves, RK (undated). Packaging of Raw Macadamia Kernels. Food Research and Technology Branch, Queensland Dept of Primary Industries, Hamilton, Brisbane.
NUT-IN-SHELL
The South African Macadamia industry is pleased to have implemented an export standard on all inshell macadamia nuts. This means that the Perishable Products Export Control Board (PPECB) need to inspect every consignment of macadamia nuts that are due for export as inshell to ensure it conforms to the minimum standard.
