RE SEARCH Maybe it would be better to call the potato a vegetable A ll speakers at the Potato Congress agreed with the conclusion: the potato is not a boring component in a meal that only supplies undesirable carbohydrates. After a first session during which all participants were able to voice their expectations for the day, Professor Jaap Seidell, Professor in Food and Health at the VU (Vrije Universiteit) in Amsterdam, immediately jolted his Audience awake. In his first talk about the potato, he stated that the carbohydrate content of the potato wasn’t really all that bad. ‘The Glycemic Index of the potato is, indeed, high, but it’s more important to look at how people eat potatoes. Nutritionists talk about food and then home in on the chemical structure of a nutrient. It’s irritating that, for the potato, they only home in on starch. When you only eat potatoes, like those people in the famous Potato Eaters painting by Vincent van Gogh, they do, indeed, cause glucose peaks in the blood. What scientists fail to consider in their studies, however, is the effect of satiation. It’s not really very easy to eat too many potatoes in their purest form, because the Satiation Index is too high. Also, we usually eat potatoes in combination with meat and vegetables, for example. In this combination, the Glycemic Index is very low. The reason why the potato is not considered a vegetable in the Netherlands has everything to do with nutritional insight’, the Professor explains. If we look at the plant family of the potato, the Solanaceae (nightshade), Seidell argues that it would be better if we placed the potato in the vegetable category. ‘The tomato, egg plant and capsicum are also part of that family. If you then also look at the composition of the potato, it has more in common with vegetables than with other sources of starch such as rice and pasta’, the Professor emphasises. Seidell is therefore surprised about the fact that the Netherlands is one of the few countries where the potato is considered the staple starch source of a meal. ‘It’s irritating that for the potato they only home in on starch.’ Potato fibre is a strong selling point The various scientists then took the potato apart down to cell level in a number of in-depth sessions. What emerged was that dietary fibre is becoming increasingly important in our daily diet. The daily recommended amount of fibre is 30 grams. The potato in its skin, with a fibre content of 4 percent, scores very high and can even be compared to wholemeal pasta. Fibre is important because it causes a sense of satiation due to their water intake. In addition, they have a positive influence on the fermentation process in the intestines and stimulate defecation. According to Henk Schols, Professor in Food Chemistry at Wageningen UR, a great deal of research is still necessary into the effect of indigestible fibre on health. ‘What has been shown is that one fibre isn’t the same as another. This allows different types of fibre in food to regulate the action of the intestines. So it’s important ‘We usually eat potatoes in combination with meat and vegetables, for example. This combination has a very low Glycemic Index’, says Professor Jaap Seidell. that fermentation takes place in the entire intestines and not only at the beginning or at the end. This makes the type of fibre in potatoes very interesting. In addition to pectin, the potato also contains resistant starch. This is an indigestible starch. It’s a fibre that ferments fast in the first part of the intestine, releasing the healthy butyric acid. This fatty acid benefits our bowel action. As a result of the fast fermentation of this resistant starch, the other fibres in the intestines remain available for fermentation in the other parts. We generally accept that this is healthy for the intestines’, Schols explains. The content of resistant starch can be influenced by the way it’s prepared, Piet Buwalda, Starch Technology Manager of Avebe and Wageningen UR, continues. ‘When potatoes are allowed to cool down after boiling, the resistant starch content increases. So, a potato salad has a higher fibre content than hot, boiled potatoes. This is the result of the chemical process that takes place after boiling and cooling down’, the researcher explains. ‘As the intestines are the largest immune organ in our body, proper bowel action is essential for good health’, says Jurriaan Mes, coordinator of the FibeBiotics project of Wageningen UR, as an afterthought. ‘In addition to the quantity of fibre, the variation in fibre is also important for good bowel action. Because there are different types of bacteria active in the intestines, different types of fibre and carbohydrates are necessary for optimally-functioning intestinal flora. In a number of interviews with young dieticians it also becomes clear that, during their training, not a great deal of attention was paid to the role of potatoes in a diet. So it’s important during congress days like those in Amsterdam to get information about the latest insight on this important food. ‘An information day like this one here in Amsterdam is certainly worth repeating’, is the reaction of many participants. ● Jaap Delleman Potato World 2016 • number 3 35 Pagina 34
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