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Agricultural chemical residue analysis in wine

Introduction

Agricultural chemicals are used widely in the wine industry to ensure that sound grapes are delivered to wineries.

The use of these chemicals is tightly controlled by government agencies.

Limits are set for the amount of residual chemical that is allowed in wine and elaborate testing is available commercially to ensure that these limits are not exceeded.

There is, however, no industry-wide monitoring for these residues in Australian wine, a situation that leaves the industry as a whole in a vulnerable position in its overseas markets.

Agricultural chemicals

Agricultural chemicals are widely used in the Australian wine industry to control a variety of pests that can affect the quality of the grapes supplied to a winery for winemaking.

According to the Agricultural and Veterinary Chemicals Code Act 1994 an agricultural chemical is a substance that is ... used as a means of directly or indirectly:

  • destroying, stupefying, repelling, inhibiting the feeding of, or preventing infestation by or attacks of, any pest in relation to a plant, a place or a thing;
  • destroying a plant; or modifying the physiology of a plant or pest so as to alter its natural development, productivity, quality or reproductive capacity
  • modifying an effect of another agricultural chemical product; or
  • attracting a pest for the purpose of destroying it

The availability of these chemicals is regulated by the Australian Government through the Australian Pesticides and Veterinary Medicines Authority (APVMA).

All chemicals must be registered by APVMA before they are able to be supplied and sold to end users, such as grapegrowers.

The APVMA also set maximum residue limits (MRLs) in accordance with good agricultural practice.

The role of APVMA is:

to independently evaluate the safety and performance of chemical products intended for sale, making sure that the health and safety of people, animals and the environment are protected. Only products that meet these high standards are allowed to be supplied.

Food Safety

Although APVMA regulate the registration of agricultural chemicals they are not the regulator when it comes to any residues of these chemicals in food products.

This is the work of Food Safety Australia New Zealand (FSANZ). FZANZ is the independent statutory agency for both Australia and New Zealand. FSANZ develops the Food Standards Code which describes the standards needed for safe food supply in both Australia and New Zealand.

In Australia FSANZ adopts the MRLs set by APVMA for agricultural chemicals that are allowed in foods and drinks.

These are the limits that all growers and manufacturers of food products must abide by; this of course includes grapes and wine. All grapes for winemaking must meet the MRLs to be fit for sale. MRLs in wine vary from country to country.

The MRLs adopted by FSANZ for food and drink products consumed in Australia may be different to those adopted in overseas countries.

So wine destined for export is subject to different MRLs, depending upon the destination country. For example, dimethoate has an MRL in Australia of 5 mg/kg and in Europe of 0.02 mg/kg, some 250 times lower.

Testing As there are many agricultural chemicals that can be used in a vineyard, the testing for chemical residues usually involves testing for many chemicals at the one time.

These groups of tests are usually known as screens and may involve up to 50 chemicals being tested in one sample at the one time.

As the chemicals all need to be separated in order to be quantified, chromatographic techniques are commonly used as these are the best techniques for separating components.

As the MRLs are also typically in the very low part per million or part per billion levels, mass spectrometry is also very commonly employed.

This of course is very specialised work and there are several labs in Australia that do nothing but test for these chemicals in a wide variety of crops and animal foods.

At Vintessential we receive many samples for this type of analysis.

Some of the equipment used for this work is shown in figures 1 and 2. Residue Surveys Many grower or producer industries do regular annual surveys of their produce to ensure that residues of agricultural chemicals in their products are below the allowable MRLs.

The Australian Government Department of Agriculture, Fisheries and Forestry (DAFF) have a section, the National Residue Survey (NRS), that co-ordinates these surveys on behalf of the industry concerned.

For example, NRS run surveys for over 50 plant and animal products. In the plant area this includes apples and pears, grains, onions, macadamia nuts etc. Animal products such as beef, pork, and seafood are included in the animal product area.

The funding for these surveys comes from the industries themselves, the role of NRS is primarily a co-coordinating one.

This role includes procuring laboratory services in a competitive tender process and also ensuring contracted laboratories meet best practice in terms of their analytical performance.

To quote from the NRS website

The primary purpose of NRS is to facilitate key export and domestic market access for participating industries by:

  • providing residue testing services that are technically sound, risk-based and structured to meet market requirements, within a specified budget
  • providing scientific and policy advice on residues and contaminants to the Australian government and industry underpinning participating industries’ quality assurance projects
  • providing support to industry and government in settling matters concerning residue-related trade incidents
  • maintaining a database of residue test results for the use of participating industries, when legally acceptable.

Wine industry surveys for chemical residues

According to Steve Guy, Compliance Manager at the Australian Wine and Brandy Corporation (AWBC), there are currently no industry-wide surveys for agricultural chemical residues in the Australian wine industry.

The AWBC has in the past had these surveys performed on an annual basis, however for the past few years there has not been sufficient funding for this to be done.

So, unlike other major food export industries, the Australian wine industry does not have any current industry-wide data on whether the chemicals used in grape and wine production are within existing MRLs.

This is not to say that the MRLs are being exceeded, but that the data is just not available. Of course individual producers can, and do, get their own residue testing done.

But this is usually confidential and only for the knowledge of the producer themselves.

According to Kevin Healy, Manager Plant Programs at NRS, “a comprehensive residue monitoring program could be used to assure overseas customers that Australian grapegrowers and winemakers use agricultural chemicals appropriately”.

“Data collected from such a program could be used to keep markets open if a residue incident arose. Similar data has been used by other industries in the past to show that the residue incident was an anomaly rather than a systemic problem.” 

Conclusion

Agricultural chemicals are widely used in the Australian wine industry.

The chemicals and the residues that may be left in wine are highly regulated by both APVMA and FSANZ.

The testing for these residues is a sophisticated and readily available commercial service in Australia. Many producers avail themselves of these services.

Although many other Australian food export industries use the services of the NRS to ensure that they meet MRLs, there is no wine industry survey on a regular basis to monitor the residue levels and thus ensure that MRLs are met.

It does appear as if the Australian wine industry is leaving itself in a vulnerable position if bad press in our overseas markets suggests that our wine is contaminated.

These stories do appear from time to time and it is up to people like Steve Guy to defend the winemaking practices and integrity of Australian wine. Without hard data in regard to chemical residues, this task is made much harder.

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