Lichtgedanken 02

Editorial 37 02 | LICHT GEDANKEN Wolffia globosa, a small rootless water lens, clearly has the potential to make it big. Working with professional col- leagues in Kerala (India) and Germany, scientists from Jena have examined the potential of various water lenses for human nutrition. The results are promi- sing. They have been published in the specialist journal »Food Chemistry«. »Water lenses could certainly serve as a source of protein for human diets,« says Prof. Dr Gerhard Jahreis. It is no coincidence that water lenses are called »green machines«, the nutritionist adds. Jahreis says the water lenses are comparable in their protein content to lupins, rapeseed or peas. The protein yield is around 30 percent of its dry weight, he says. He explains that the little water plants are definitely to be ra- ted as valuable from the perspective of nutrition physiology, particularly with respect to the composition of the ami- no acids – the components from which proteins are built. »All amino acids are present at the levels recommended by the World Health Organization,« Jah- reis emphasizes. The tiny plants also contained valuable omega-3 fatty acids, he continued, such as stearic acid and alpha linolenic acid. The proportion of starch is comparati- vely low in water plants. Only four to ten percent of their dry weight consists of starch although the proportion de- pends largely on their conditions for growth, he states. That also makes the green water vegetable interesting as a food that is particularly low in calories, according to Jahreis. Fast reproduction with no additional fields »The water lenses reproduce very quick- ly but do not need any additional cul- tivation space,« says PD Dr Klaus Ap- penroth. He adds that this represents an enormous advantage compared with soya, for example, in view of the decli- ning space for cultivation. Water lenses had been on the menu for millennia in Asian countries such as Thailand, Cambodia and Laos, he continued. In particular, he points to the species Wolf- fia globosa which in Asia is served as a soup, vegetable side-dish or omelette. In the current tests conducted by the research group, Wolffia microscopica pro- ved the most promising. For the present study, the researchers examined six different species of water lenses: Spi- rodela polyrhiza from the USA, Landoltia punctata , Wolffiella hyalina and Wolffia microscopica from India, Lemna minor from Germany and Lemna gibba from Italy. First, the plants are cultivated for 14 days in an Erlenmeyer flask in a culture medium, as can be seen in the photo (p. 36). During this period, a thick, floating lawn sprouts from a few plants sown. Subsequently, the green biomass can be harvested and freeze dried for chemical analysis. First pilot plants for producing duck- weed on a grand scale »So far, the duckweed has not been cultivated for larger applications but simply ’harvested’ from bodies of wa- ter,« says Klaus Appenroth. The plant physiologist has devoted almost his en- tire career as a researcher to these tiny plants and among other things, built an extensive collection of Lemnaceae (English: duckweed). Nevertheless, he says, the first pilot plants have been set up in Israel and the Netherlands in which water lenses are produced on an industrial scale – primarily for biomass production. Another factor in favour of using the plants for human consumption in the future is that, according to the authors of the study presented, water lenses can easily absorb trace elements dissolved in the water. In this way, diet-related deficiencies could be compensated with little effort. Klaus Appenroth (r.) and Gerhard Jahreis inspect the extensive collection of water lens plants in their laboratory. Water lenses are already consumed today, primarily in Asia, and that is where the requirement is greatest, they say. The diet in India, in particular, with its high population, is heavily biased towards starch due to their consumption of rice, while proteins and trace elements are often missing in the food. The addition of water lenses rich in valuable protein and trace elements, could provide a remedy, according to the conviction of the researchers from Jena. The climatic conditions in the Indian subcontinent are also ideal for cultivating water lenses. The »snack from the pond« still has to establish itself in European cuisine. Water lens smoothies are conceivable or biscuits produced free of gluten.