Food Testing at Hill Laboratories
Fruit testing for chemical residues is undertaken on behalf of kiwifruit exporter Zespri
Hill Laboratories is an independent and locally owned testing business started by Dr Roger Hill 31 years ago for soil testing. Dr Hill and his family and staff are the business owners and son Jonathan is the technology director for the company.
Now it has expanded significantly with agricultural testing only making up 25% of its business. A new robotic system using near infra-red technology is used for soil and plant testing.
The company has diversified widely and now water testing makes up a major part of its business.
It’s a major employer with 350 people employed across several different locations including four sites in Hamilton. It also has sites in Christchurch and Blenheim.
The water testing is for regional and district councils. A wide range of other testing work includes testing for asbestos and methamphetamines. Food testing is also a large part of the business.
Hill Laboratories is a world leader in methods to test food for chemical residues. Last year scientist Dr Bruce Morris won a gold medal for a paper he delivered at an international conference in Florida about preparing samples for residue testing.
Food testing is mainly carried out for the export market, although some local market work is also done. The real driver is where chemical residues are the barrier to export samples or products to overseas markets. There is a requirement to demonstrate that food has no residues.
Residues are a challenging area analytically because the newer chemicals which are used, break down very rapidly compared with older chemicals such as DDT which were very persistent.
Dr Hill says as we have become more environmentally aware and use softer chemicals, the testing methods have to detect minute quantities such as parts per billion levels. Sometimes instruments for measuring the chemicals have to be at 200-300degC, so compounds present break down during the process. But the speed of analytical developments has been very impressive, he says.
Up to 600 compounds can be screened for at one time for one crop. The business has two to three technologists constantly developing analytical methods for new chemicals.
Last year they made a major breakthrough in testing for residues by developing a way to prepare samples, and as a result now have a world leading reputation in this area.
The instruments they use in residue testing are valued at between $300,000 and $600,000 each.
Hill Laboratories has been working in Japan for approximately nine years and has a sales office there, where it sources a lot of residue testing work, for example in green tea. They collect food samples in Japan and send them back to NZ for testing. Now the company is moving to use a large international agency (DKSH) so it can expand its testing work throughout the Asian region.
One of Hill Laboratories’ largest food testing contracts is with Zespri to comprehensively test kiwifruit before picking. Every block of kiwifruit is tested before picking for export.
The lab deals with a huge influx of samples, and with the onset of the Psa problem and the use of antibiotic sprays to control the disease, sampling systems have become complex.
Hill Laboratories has had to design systems to process very large numbers of samples very quickly.
The lab can look for individual chemicals or it can take a blanket look across a very wide range of compounds.
They take a sample of 30 fruit, and used to freeze them overnight and then grind up the fruit before testing. Now they snap freeze the fruit to speed up the process.
The problem of glucosinolates in swedes started in 2014 with some South Island cows dying when grazing particular swedes.
DairyNZ co-ordinated the whole project, and Hill Laboratories were contracted to provide the chemical analyses of the swedes. The project presented a very similar analytical challenge to the residues, using similar analytical techniques. Dr Hill says “It wasn’t just one chemical compound, but a whole group, collectively known as glucosinolates. It took quite a while to develop a reliable method, but it was important we got it right, and we now have a method that can be used for any future monitoring.”