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Feature

Searching for the Super Spud

Finding the perfect potato is not an easy task.

Peter Meredith

Almost every day I receive enquiries about potatoes. Many of the enquiries are complaints about cooking quality and particularly about the inability to know how the spuds will behave in cooking.

There's nothing new about that and I suspect that there always has been a high level of complaints since potatoes became a staple foodstuff around 1600 AD. Quality control and quality assurance have become common phrases in trade nowadays. There is an ancient belief by consumers that if only they knew the "variety" then they would know what they are getting.

This belief in variety goes back about five generations, or about 150 years, which takes us back to the great potato famines of Europe in general, and Ireland in particular, when the great blight struck the almost monoculture subsistence farming of the peasant populations with over two million people dying in Ireland alone.

The surviving people noticed that some lots of potatoes didn't succumb to the blight; they had an inbuilt resistance to the disease organism. The organism is still around, and one of the aims of plant breeders is to introduce more and more resistance to all sorts of diseases into their new varieties. Even after the main wave of blight had passed on after two or three years, the resistant lots still grew better and yielded more tubers per plant than the others.

This was the origin of the idea of varieties such as Lumper, White Elephant and Irish Cobbler. This idea has remained in the recesses of our minds, so that we believe that variety name is a good indicator of "quality". Few of us still grow our own potatoes and the idea of quality has moved from the growing characteristics to the cooking characteristics. So now variety name is considered an indicator of cooking quality.

Look through the potato recipes in many cookbooks and you will see instructions such as "take six large floury potatoes" or "take some firm-cooking potatoes". The author knew that not all potatoes cook alike. Technical texts for professional cooks will tell you how to sort out which is which. The amateur cookbooks may suggest that certain varieties are good for this and other varieties are good for that. Some advertising leaflets make suggestions of that kind.

Vegetable growers obviously still believe that variety is a good enough descriptor, and many individual growers and packers name the variety on their packs. But many of the supermarket packs don't even do that yet.

I once asked Allison Holst how she made the decision about getting the right potatoes and she said she keeps several large bags of different purchases and has learned from trying them what each is good for. The public would like the industry to have done the trying on their behalf and sell them potatoes that are labelled (and maybe even guaranteed) as suited for particular purposes.

One of the problems is that the people who carry out trials for the industry are generally making comparisons of several varieties grown side by side in the same place at the same time. Quite understandably they believe that variety is what matters. It's not so easy to make good comparisons of one variety between several places and over several seasons or even during one season. Potatoes are living beings and change continually with time.

Growing Conditions Important

In 15 years of studying potatoes and particularly in making measurements that are definable reproducible numbers, it has become more and more apparent to me that variety is not the most important thing in deciding how spuds will cook. Where, when and how they were grown accounts for about two-thirds of the variation in cooking qualities, with variety only causing one-third of the variation.

It's another example of the "nature or nurture" effects on development, how much is due to genes (variety) and how much is due to surroundings (climate, soil and skill of the grower). And to complicate matters, of course some genes express themselves more markedly in better (for them) growing conditions; there is interaction. But I am of a firm belief that from the user's point of view the spud grower is more important than the spud variety.

Potato producers want to sell the spuds they grow; that's why they're in business. To be successful they need satisfied customers. The customers that I deal with are somewhat dissatisfied with what is delivered to them at point of sale.

There isn't a lot of advertising of potatoes in New Zealand, but advertising is necessary for two reasons: first to gain attention for the idea of potatoes and, second, to give a preconception of satisfaction. Sell the idea that they're good and convenient, with perhaps a hint that they're economic too.

Looks are everything in making a sale, as all real estate agents know. That's the reason marketers put so much emphasis on packaging. Company annual reports and share prospectuses are very expensively produced and designed to impress because the board has something it wants to sell us. Producers should be thinking similarly about their potatoes.

A display or pack of uniformly sized and shaped potatoes is more attractive to the purchaser and will sell more readily and for a higher price. The customer, above all wants convenience when buying. The potatoes must look good, however they are presented.

A window in the bag helps. The consumer still has memories of jute sacks of dirty half-rotten potatoes in large quantities, and that memory will be the most difficult marketing problem to deal with. The pack must be transportable with ease. A handle helps. The quality must be identifiable; colour coding helps.

Performance Paramount

So the customer buys a pack. Now, performance is paramount for repeated sales, and that is what is lacking in potato vending in New Zealand today. People want potatoes for particular purposes. They want boilers to stay whole and firm; they want mashing potatoes; they want fryers or bakers. And they want guaranteed quality for these purposes. Poor performance is the commonest complaint.

A cautionary tale to show what I mean. Cantaspuds, put on the market in 1992, were claimed to stay whole when boiled and to bake well. It said so on the pack. The concept of a fitness-for-purpose claim and the packaging were quite good, but technical know-how was completely lacking. Good boiling and good baking don't exist in the same tuber -- they are mutually exclusive, which was one reason I bought samples and tested them.

The pack was underweight, a not unusual finding. On testing the specific gravity of the tubers (a routine test in factories using potatoes for manufacture) only two of the 60 tubers in the bag could have been reliably selected for stay-whole boiling. So they were also boiled individually, and only 7 of the 60 tubers did not show some degree of sloughing. Of the 60 tubers, 34 were completely unacceptable for boiling. These would have been a real liability under the Consumer Guarantees Act 1993, now in force.

Cantaspuds went off the market, but there are other similar stories, particularly of higher priced gourmet potatoes that did not live up to claims or labelling. I have examples right through from 1990 to 1998.

Spud Specific Gravity

Specific gravity of potatoes is easily measured and is a good indicator of how potatoes will cook. This relationship has been known since two French professors observed it and wrote about their findings in 1897. Almost a century has passed since then. Factories making french fries or crisps or canning salad potatoes routinely use the test.

Low specific gravity tubers contain less starch and other solids in their structure. These are the ones that stay whole and nicely firm when we boil or steam them. But if we bake or fry or roast them, they will shrink very badly and we will finish up with floppy, shrivelled french fries that are not at all attractive to eat.

High specific gravity tubers have much more starch and other solids in their cells, and so they fry, bake and roast well. Not only do they not shrink, but they don't take up so much fat or oil in the cooking, and so are better for us nutritionally.

Although growing techniques can push production towards either the high or low solids ends of the scale, New Zealand growers produce a lot of the awkward in-between potatoes, that don't fall in either of the above categories.

The French call these purie potatoes. We might call them mashing potatoes because they readily produce the New Zealand style of mash that is moist and creamy (there is also mashed potato that is dry and fluffy, made from high solids potatoes).

Now, what can I suggest? That potatoes be graded, either batchwise or individually, into one of the three grades of solids content. They can be packed in colour coded bags. The mashers might be in orange and would command a basic price because they are the most common and can be used as general purpose spuds. The high solids ones might be packed in red and can command a premium price for the effort that has gone into selecting them.

The low solids potatoes, the guaranteed stay-whole boilers, might be packed in yellow and should command a premium price because they have come from paddocks that gave an appreciably lower yield per hectare and probably needed more irrigation and general care. Above all, each of these graded packs needs a carry handle and a window so the purchaser can see the goods.

But I've left the most important to last. People don't want to buy a big range of sizes in one bag. All the same size is more attractive in appearance and much more easily used. The size range can be printed on the pack or on its label. Let people choose for themselves what sizes they want. The size grading machinery already exists. If it was used in a little better organised way the product could be given that increased appearance of quality.

The customer is paying good money; quality in appearance and quality in performance is necessary for repeat sales. It would be nice to know the variety, too, because that is a guide to the general shape, to the colour of the skin, to the colour of the flesh and often to the texture, the granularity of the cooked flesh.

How will the pack of spuds cook? And how will they look on the plate? Supermarket management could do a lot towards getting satisfaction for their customers. But the initiative must surely come from the potato growers, graders, packers and markets.

Sink or Swim Test for Potatoes

It is possible to make up your own salt solution to test potatoes.

Stir 225g common salt (table salt) with 1775 g water until dissolved, and make sure that the temperature is not too far from a comfortable 20oC. This gives an all-purpose solution with specific gravity close to 1.080.

Put your potatoes in it one at a time. If they sink they will probably cook "floury". If they float they will probably cook "firm".

Peter Meredith is a research scientist with Ilam Potato Sciences.