Mr Wang offers some evidence of that - in his four months as ambassador, he says, he has met many more officials from the Ministry of Primary Industries than from Foreign Affairs.
"It has always been the priority of my job here. The Chinese Government paid a good deal of attention to this food security issue."
Mr Wang was in China when the botulism scare happened and says it did get a lot of attention. But he does not believe it greatly tainted New Zealand's reputation among consumers.
"Hopefully not. The important thing is we learn from this. I don't think it's a bad thing. Of course some people, mothers in China, would be worried about the quality of products, that's natural. But as long as we deal with it in a responsible way, I don't think it will be a longer-term problem."
It highlighted the lessons to learn, both by the two Governments and by the private sector.
"There is no plain sailing for any bilateral relations, even in trade relations. The most important thing is how to deal with these problems.
"China and New Zealand are very different and after this incident we realised we have to understand more about each other's systems, regulation and laws."
Despite all the headlines at the time, the false alarm does not appear to have affected trade. Mr Wang believes the target of achieving $20 billion two-way trade by 2015 is likely to be reached a year early. It hit $18.2 billion last year.
"The figure for trade last year said everything about it - it was not affected. Both of us became wiser."
He said Mr Key's visit would be important to spread the food safety message and to reinforce the strength of the relationship between China and New Zealand.
China hosted about 15 New Zealand ministers last year. It will be the third time Mr Key has met China's top leaders in the past year and his fourth visit to China as Prime Minister.
"I don't think the Chinese top leadership have met any other foreign leaders so frequently. So one of the top issues will be explanations.
"But I don't think that will be the whole picture. He will send a positive message not only to China and New Zealand but to the outside world about the relationship. It's very much in good shape."
Mr Wang says the next logical step between New Zealand and China is not simply sending more and more milk powder but helping China develop its own dairy industry by exporting know-how.
"New Zealand is a very innovative and creative nation. You have very good high-tech science and technology and sometimes you keep it to yourself. You're being very humble. I think this commercialisation will be beneficial to both our nations."
Mr Wang also points to potential growth in trade in other areas, in particular a harder liquid than milk: wine.
He says that within 10 years, China will be one of the biggest consumers of wine in the world. It now imports much of its wine from the United States, Australia and Europe. But he's tasted New Zealand wine.
"It's not that expensive. It's from New World. And I think it's very suitable for Chinese consumers. Some of the wine here is very fruity. I think that tailors to the taste of consumers."
When he returns to New Zealand, he has his own sales job to do.
He points out that Chinese investment in farmland and property is small compared with that of investors from other countries such as Britain and Australia.
While most business people and figures at both the central and local government level welcomed Chinese investment, especially in infrastructure, he admits some assurance is needed among the wider public.
"That is my job. People are saying that because out of their ignorance, maybe they are not aware of what benefits this could bring to New Zealand.
So there is a need for me to promote understanding among peoples. Your land is still in New Zealand. No one can take it away."
