Food Safety
Greenshell™ mussels (Perna canaliculus) are filter feeders and filter plankton (small free-floating plants and animals) from the water column. This feeding system is not unique to mussels but is used by many bivalve molluscan shellfish, including oysters and clams.
Filter feeders, however, can filter and accumulate hazardous levels of disease-causing micro-organisms, viruses, protozoa, marine biotoxins or toxic substances, if these are present in the water.
The potential food safety problem with bivalve molluscan shellfish is recognised internationally and most countries have regulations that control where and how these shellfish can be collected for sale.
New Zealand operates a mandatory shellfish quality assurance programme for all Greenshell™ mussel harvesting areas. This is recognised as one of the best in the world and is based on international best practice. The programme is managed by the New Zealand Food Safety Authority (NZFSA), in cooperation with the District Health Board Public Health Units and the shellfish industry. For full details of this programme, refer to the Animal Products (Regulated Control Scheme-Bivalve molluscan Shellfish) Regulations 2006 and the Animal Products (Specifications for Bivalve Molluscan Shellfish) Notice 2006 (both referred to as the BMSRCS).
Before any area can be used to farm commercial Greenshell™ mussels, public health officials survey the water catchment area to identify any potential pollution from humans, wild and domesticated animals or birds, or other environmental effects. This is accompanied by microbiological sampling of water and shellfish over a 12-month period, so all seasonal influences are explored. All the information is evaluated and a risk profile established for the catchment, which determines its suitability as a food production area.
Once an area is classified and listed by NZFSA for harvest, there are requirements for regular monitoring of the water and shellfish flesh to verify environmental conditions. The samples are analysed for microbiological and chemical contaminants.
New Zealand shellfish areas are affected by microbiological contamination from run-off during rainfall events. This is managed under the BMSRCS by classifying the areas as ‘Conditional’ and closing them for a number of days after rainfall to ensure that the mussels have cleansed themselves before harvest.
Marine biotoxins can be produced by some species of microalgae under certain environmental conditions. This is a natural phenomenon, but if mussels accumulate these and are later consumed some of the toxins can cause neurotoxic, diarrhetic, paralytic or amnesic health effects on the human body. To manage this potential health risk, the BMSRCS has a specific requirement that each shellfish growing area be tested on a weekly, fortnightly or monthly frequency for each of the toxin groups - in approved laboratories using approved methods. If toxins are detected above the permissible level the Greenshell™ mussel farms are closed until the levels fall below the permissible level.
The BMSRCS has strict food safety requirements regarding transport and temperature management during and after harvest to ensure that the mussels remain wholesome and fresh until they reach the processing factories. All bags must be labelled with harvesting details so that traceback to the farm and time of harvest can occur if there any consumer complaints.
New Zealand produces a wide range of food products from Greenshell™ mussels, including half-shell mussels, mussel meat, smoked and marinated mussels. GreenshellTM mussels are also used in some dietary and therapeutic supplements. All processing factories must maintain high hygiene standards with regular verification being undertaken by officers from the NZ Food Safety Authority.
As New Zealand sells Greenshell™ mussels to more than 60 countries our growing areas, factories and laboratories are regularly audited by overseas agencies, for example the US Food & Drug Administration and European Commission. The audit reports consistently confirm that we operate a comprehensive and successful programme that ensures consumers can have confidence that Greenshell™ mussels are safe and nutritious.
