I HAVE always thought myself to be a discerning fruit buyer.

To me, all fruit belonged in one of two categories: sweet or sour.

If a fruit has good colour, is firm to the touch and smells fragrant, chances are it will be sweet to the taste and enjoyable to consume.

A recent trip to Australia to visit a few fruit growers changed all that, and gave me a fresh take on the journey of fruits.

It was grape harvest season when we visited the table grape vineyard of local grower Fruitmaster Australia in Mildura of Victoria state on March 3. Table grapes are grapes meant for consumption while they are fresh, as opposed to grapes grown for juice production, wine-making or for drying into raisins.

A grape picker was cutting bunches of grapes off the vines for harvest as pop music from a portable radio played in the background.

He was dressed in a long-sleeved shirt and long pants with a red-coloured scarf around his head for protection from the sun.

Mildura, located in the state of Victoria, had recently endured some 20 days of soaring temperatures of over 40 deg C just before the harvest season, and there was some concern among growers about how this would affect the quality of the fruit.

"When there is too much heat, the grape matures and becomes sweet before the colour has time to properly develop," explained a table grape producer who wanted to be known only as Vaughn.

Such grapes cannot be sold as top-grade grapes, which usually are exported to premium markets such as South Korea and Japan, where consumers are willing to pay top dollar for high-quality fruits.

Singapore, on the other hand, is a price-conscious market willing to pay only for "reasonably-priced" grapes which tend to belong to a secondary grade, explained Mr David Minnis, chairman of the Australian Horticultural Exporters Association and managing director of Minnis Horticultural Services.

Other places that accept secondary-grade grapes are the Philippines, the Middle East and the domestic Australian market.

Over at Mildura Fruit Company (MFC), Australia's largest citrus packer and exporter, general manager Perry Hill said the sweltering heat would most likely affect the size of the citrus fruits being grown, and slow down their growth, but "would not affect the quality of the fruit from the customer's point of view.

MFC, which is licensed to pack Sunkist oranges, exports mainly to Hong Kong, Japan, China and the United States.

When the citrus fruits are ready for harvest from April, they are processed through a facility with state-of-the art sorting technology.

At Sunwest Packing Shed owned by local grower and packer Seven Fields, high-speed cameras capture 20 photos per fruit as weight scales take the weight, to determine the weight, diameter, colour, density and degree of blemish on the fruit. This in turn determines the grade of the orange.

Seven Fields, whose flagship brand is Sunwest oranges, also has a scanner that measures the sugar level, known as brix, in each fruit. The machine sends an infrared signal into the fruit, and it measures the sugar level by the amount of light that bounces back, explained produce marketing manager Brett Jackson.

The technology, considered rare in Australia but common in the US, is used mostly for fruit meant for the premium South Korean and Japanese markets, where the sweetest fruits go, said Mr Jackson.

After the fruits are sorted and graded, they are labelled with codes and packed into boxes ready for export. And that is how they end up at your nearest supermarket.

It is a little bit of a letdown to learn that despite paying a pretty penny for my fruits here in Singapore, I am not getting the best possible fruits there are in the world.

But if getting the best means having to pay S$60 for a Japanese melon, I think I am quite satisfied with my well-coloured, firm and fragrant "reasonably-priced" fruit.