Farming, Plant Nutrition and Food Quality

Jens-Otto Andersen
Research Assistant, University of Copenhagen

Ladies and gentlemen. Agriculture must be looked upon as the primary health service. These are basic words and this morning we have heard about the re-integration of science and spirituality. I am just picking a few words from the speakers, de-vitalised food, form and organisation in nature, the importance of the study of energy to expand the quality concept, the living organism as a critical entity, vitality and so on. It is quite clear that we are at some kind of threshold and I have been invited to present two methods which in my view represent an attempt to somehow try and deal with this threshold. How do we bring about new concepts? We hear the new concepts here, how do we develop the methods which meet these concepts? How can we operationalise in a scientific manner? When we look back at all the many investigations which have been made in comparing organic and conventional products I would say of course I am biased, but I feel confident you are biased also, so I will probably get away with it.

I would say that from looking over these many investigations there is good evidence to show that there are significant recurrent differences between organic and conventional crops and food products, and that we can measure these differences. We can measure them with, we all know the dry matter, the content of nitrate, C vitamin, storage ability, enzyme activity, protein, energy and so on and so on. We could sum up these parameters and call them primary compounds, primary metabolites, primary methods. So my basic statement is that if we want to somehow struggle with words like holistic and vitality we of course need holistic methods and the question is how do we go about this. I think here we are in the same situation as the fat man who wanted to play the noble game of golf. He was a big man and he had the dilemma that when he could see the ball he could not reach it, and you know of course what I am going to say, when he could reach it he could not see it.

I think this is the situation that we are facing in science. We have this concept of the living organism as a critical entity. We speak of wholeness, wholesomeness, we speak of holism, but the critical thing is how do we develop methods to get to this wholeness. Because when we use the primary methods, we always start by pouring acid over the whole thing so that it is absolutely devoid of life, before we start measuring nitrate and C vitamin and enzyme activity and so on. So it is quite a challenge. What I have been asked to talk about is the so-called secondary metabolites and bio-crystallisation. On the subject of secondary metabolites, I will present the work of one of my colleagues Bodil Soagaard. She had the honour of, I would say, putting this important theme on the agenda of Danish organic research and it is now spreading. Can I have the next slide. OK.

This is not a chemistry lecture but we have to go through some exercises and I will try to make them a little organic. I will talk about these secondary metabolites in this sense. If you picture an ice mountain, we all know that most of the ice mountain is below the water and the point here is that the primary compounds, the primary metabolites that we measure, dry matter, vitamin content, protein carbohydrates etc, the way we normally measure quality only represents the very peak of this ice mountain. Anyone who has dealt with just a little bit of chemistry will know that the chemists have identified and classified and named literally millions of compounds and we could put them together and call them secondary compounds in nature, in the plant kingdom. The reason to distinguish primary and secondary are in most cases that the primary are those that we know something about, for example, we know something about nitrate and the relation to health.

When we come to the secondary metabolites, we have identified the compound and we know a little but we really do not know how to go further with this. It still awaits further research. What I will try to do in connection with the secondary metabolites is to take you on a small guided tour, to maybe open a little door to show you the where we are now. We are dealing here with ginger, the quality of ginger. We all know ginger is basically divided chemically into a sharp fraction and an aromatic fraction. We taste the sharp fraction, we smell the aromatic fraction. The sharp fraction can be divided into these secondary compounds and they can be isolated and determined chemically by means of gas chromatographic techniques. There are many of them and they are based on a general skeleton, a green one on the illustration, but mother nature is playing variations over a musical theme and this is the vast difficulty which is connected to dealing with secondary metabolites. We do not have isolated compounds like nitrate or C vitamin. We have a huge abundance of variations over a theme, and not only one theme, we have a whole orchestra playing together and they play their notes separately. We all know that Mozart is not made out of nitrate and protein and C vitamin, so the question is how can we make sense of this secondary symphony so to speak.

Firstly, I will briefly just present a few of these groups of secondary compounds. The phenolic compounds, from the sharp fraction of the ginger are all secondary metabolites and these phenolic compounds are extremely important in that many of them are anti-oxidants. That means that they neutralise the free radicals which otherwise would induce severe damage on our metabolism all the time, induce cancer and so on. I hope that you are familiar with them. The flavonoids are present in all fruits and vegetables and they are known to regulate hormones which regulate cell growth. They are important in cancer preventing, tannines. The bitter element in many crop plants are known for many pharmaceutical effects. The alkaloids opium and morphine are the most well known, they have in many cases a powerful effect on our nervous system. All these secondary metabolites we find in spice plants and in medical pharmaceutical plants and this is well known. Now we are talking about ginger but we also find them in all the crop plants, in smaller amounts. It is not obvious that they are all there but I would say that they are absolutely always playing in the background and we can chemically demonstrate that they are there.

Now we come to the main hypothesis. If agriculture should be the primary health service, where should this health come from. If we include the whole ice mountain I would say that health must include these secondary metabolites because they are known for their powerful pharmaceutical effects. We can talk about anti-oxidant cancer prevention, healing wounds, affecting nerve system and so on and so on. The fraction I showed you from the sharp fraction of the ginger has been demonstrated to have an enormous effect on healing ulcers, induced experimentally on rats. You simply induce some acid in the stomach of the rats and before this you have given them some fraction of this ginger, the sharp fraction, and it has an enormous effect.

This slide shows the aromatic fraction in the ginger and the only thing I want to point out here is simply to show you how this is detected chemically. In the chromatographic techniques, this is the HPLC technique, we get this mountain landscape and every peak represents a secondary metabolite, a phenolic compound, and the size of the peak represents the amount. Now the African ginger is known to be the best and this is due partly to the amount of secondary metabolites but also to the relation between them. Here we come to the question of synergy and interaction and so on. This is very complex.

Now let us try and get into something which is more related to agriculture. We all know the plant plaintain. Experimentally we can induce a fungal disease on leaves of this plantain and we can measure that the plant responds immediately by increasing the concentration of caffeic acid in the leaves (10 times or something like that has been demonstrated) and just around the zone of attack this concentration is even much higher. What actually happens is that the plant kills a part of its own tissue in order to prevent the fungus from establishing itself and it is very successful in this case. Zone 4 represents a non-attacked zone and the columns show that there is much less caffeic acid induced in this area.

Here we should, and again do not despair, this is not a chemistry lecture, but just to show you how mother nature is playing this organ, caffeic acid is also a phenolic compound which looks like this according to the chemists. Below we see another phenolic compound which we know from two plantain varieties, and we are here dealing with another fungal disease, mildew. It has been shown that out of these two varieties one is resistant to mildew and the other is not. This has been correlated very strongly to the presence of two phenolic compounds and they are distinguished by this R at the bottom. In one case we have a glucose there, in another case we have a ramnose, which is a small sugar. Can I have the next slide?

Now let us get even closer to practical farming and the connection between barley, nitrogen fertilisation and the secondary metabolites. This is a very simple experiment. You have on your left side, a print-out from these secondary metabolites, the phenolic compounds from a barley extract. This soil is state research soil from Denmark and the amount of mineral nitrogen here is approximately 100 kilos of nitrogen corresponding to 100 kilos per hectare. On your right side you have another standard soil with an amount of approximately 380 kilo nitrogen per hectare. What you should notice is the amount of phenolic compounds, the diversity and what you should especially notice is that the middle red peak which represents caffeic acid. This experiment demonstrates that when we go up 380 kilos of nitrogen, it is very high and we are talking about research, it is very high but see here that this caffeic acid which we know from plaintain to be able to prevent a fungal attack is more or less absent when we go up in the level of nitrogen. I hope this is clear .

This is a crucial finding. It has been known for some years but it is more the consequences of it. Next slide please. Now we finally come to practical agriculture. This is a classical experiment with mildew attacks observed over the summer, starting at the middle of May going to the middle of June showing the degrees of mildew attack. High values mean a high attack. We have four different levels and types of applying this nitrogen and what we of course see here is that when we have our full application it is determined here as 100%, it corresponds approximately to 180 kilo of nitrogen per hectare. This is to my knowledge way below the recommended levels in conventional agriculture. Correct me if I am wrong. What we see here is simply an illustration of mildew development in conventional and organic agriculture in general, the two upper lines represent different types of conventional agriculture, the two lower parts represent two types of organic agriculture. We see that the mildew does not develop in the two lower types not at least to a point where the quality of the crop and the yield is in any way seriously damaged. We do not have any corresponding measurements here of the phenolic compounds but I hope you can see the connection here. This ability of the crop to prevent the attack is no doubt connected to some kind of phenolic compounds.

Next slide please. I will now turn to another crop, celery. Two varieties of celery. You have on your left side Monarch, I do not know if it is used in England. We have on the right side Snow White, an older one, it goes back to the 50’s, but is still used. What this chromatographic phenolic output shows is simply another example that the quantity of phenolic compounds differ quite a lot among the varieties. These varieties are grown on the same farm in the same year with the same conditions.

Next slide please. What we see here is a brief stating for measuring the content of dry matter in five celery varieties in four organic farms in Denmark, an experiment conducted in 1996. We see right away that the modern varieties, especially King and Monarch, have a very low content of dry matter relative to this old classical variety Snow White.

Next slide please. Again in both cases from these varieties we are examining the dry matter fraction. What we see here is when we have taken out the dry matter fraction from this variety and we measure in a comparable manner the content of phenolic compounds, we see that they differ, even though we have already isolated the dry matter content.

Next slide please. Okay, so secondary metabolites, phenolic compounds, conclusions, where are we? We find variations between use of nitrogen which is not surprising. We know that from a thousand experience, this will always happen no matter what we measure on. We have major variations between soil types which is not surprising either. We have major variations between varieties. Now we come to something which we can so to speak manipulate in practical farming. What I would like to point out is that and here comes a personal hypothesis, I have to be honest and say it is a hypothesis, I am sure you will agree. Since the second world war most of plant breeding has been conducted in order to gain high yields using high amounts of mineral nitrogen in combination with pesticides which can keep away this mildew and so on. Today we are in the organic farming, we are so to speak referred to varieties which originate in the breeding system and we see the effects on the secondary metabolites right away. In my view the two most important conclusions are that an increase in nitrogen level generally reduces the quantity and the diversity of secondary metabolites here specified and exemplified with phenolic compounds.

I would also like to present just a brief corner of my own research which is in the area of bio-crystallisation, copper-chloride crystallisation. I hope you are basically familiar with this type of pictures. You see on your left side a carrot crystallogram. On your right side you will see a barley crystallogram. Mr Peter Segger will later present in detail the method. We do not bother about the experimental background, we just conclude that the order and now we come back to some of the concepts which were introduced this morning, the organisation of the picture, I prefer to say the co-ordination, you could say of the order, the harmony is strongly affected by soil type, type and level of fertilisation especially nitrogen fertilisation. What we see is the order, the co-ordination of the picture is reduced when we go up in nitrogen as a general result. Peter Segger will also discuss this. I will stop there in order to keep the time.

Next slide please. This method, in my opinion, just like the secondary metabolites, can offer one way further in this direction towards more holistic methods. What we are facing are challenges to improve the present technical basis for crystallisation and this is what has been the main part of my project at the university. The second part of my work has been to evaluate and quantify the pictures, because when you go into this method you are immediately faced with the difficult task of how to evaluate a picture. We know that a picture says more than a thousand words but how do we make science out of this. We have a few skilled people in the world who can read tremendous things out of these pictures. I am not one of them so I have to go to computerised image analysis. What we have tried to develop is in cooperation with computer people, software which can quantify these pictures in a standardised way. I will present very briefly, the experiment using fresh carrot extract. You have a first day picture on the left side. It is a poor picture. The original one is better. This extract is put in a refrigerator at 6 degrees Celsius and over 7 days every day you make a new picture. Chemically we can observe that the macro-molecules, the proteins, the secondary metabolites are broken down in the extract over this period. What we see in this picture is that the co-ordination of the picture is gradually broken down. So here we see examples from the first, the fourth and the seventh day. Our aim was to be able to distinguish, to discriminate pictures from each of these seven days.

Next slide please. We did that on the basis of what is called texture analysis in the image analysis science. I have stated some characteristics here which I will just mention very briefly. We scan the picture with 256 grey levels, colours are out, and we use 4-5 resolutions. We use a statistical method called discriminant analysis to actually place an unknown picture into these seven groups. We use a total of 23 image parameters. When this is combined with the resolutions we have a total of 107 parameters per picture. What we have so far, is that this software is able to discriminate correctly three pictures from each of these seven days when these pictures are presented to the programme as unknown pictures. First we present the pictures to the program and tell them that these pictures belong to this group and afterwards we present them again as unknown pictures and the software will classify the picture, and we have 100% correct classification. So our aim is fulfilled.

Next slide please. This is just an illustration of the actual data that we get out from the texture image analysis parameters. This is not a physical parameter, but you will see that the energy is going down and you will also see that the entropy is going up. The entropy is in the lower right corner. Why is this interesting? It is interesting because when we make this degradation series based on the same extract over seven days we see this degradation, this dissolution of co-ordination. The sad fact is that when we examine carrot samples from practical farmers we see that these samples are actually within this range, so the question is of course what does this matter in terms of health.

What are the perspectives of these matters? In my view the perspectives are if we want to strengthen this connection between agricultural products and our food and farming we have to include secondary metabolites. Phenolic compounds are just an example and this research is just the beginning. We have to include it because potentially the plant is a walking pharmacy, the plant is a walking pharmacy. When we speak of the bio-crystallisation methods we can include other methods.

What is health? Health is basically the ability of an organism to keep together the life processes in an ordered manner. This is infinitely complex but we can break it down to these concepts: to be able to maintain and develop the life processes in an ordered manner, in a dynamic process under constant pressure from the surroundings. The bio-crystallisation method offers one aspect of this order, the increase and the decline in this order. We can also find a number of other methods which are at our disposal now; we can talk about bio-photones, physiological index etc. There are many promising methods. The aim is in my opinion to come to the point, unlike the fat golfer, where we can both see the ball and reach the ball. In my view this point will be reached when we have developed parameters like a vitality index. Vitality is a tricky thing and according to what our personal concepts are it can be interpreted in many ways but I think if we put an effort into going in this direction, finding a vitality index, combining various methods, we will have come a long way. Thank you very much.

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