Nutrition Analysis And Food Safety Evaluation Of Green Tide Algae

The large-scale outbreak of“green tide”had taken place in the Yellow Sea for four years since 2007 and aroused widespread concern from various sections of society. In this paper, the nutritional components of green tide algae and their toxic and hazardous substances heavy metals potentially contained were determined and analyzed, in order to provide theoretical basis for the comprehensive development and utilization of the green tide algae.The phenomenon chlorophyta algae proliferate in eutrophic coastal waters all over the world was not uncommon and it also frequently happened in Europe、North America、the Mediterranean and tropical waters of the eutrophic inner bay and intertidal zone. The species caused“green tide”were mainly chlorophyta Ulva genus algae and the photosynthetic capacity of these algae was very strong. Compared with other algae, their modes of reproduction were more and they could cover the algae growing areas soon. The large-scale outbreak of“green tide”could cause various environmental problems and at the same time the stench issued by the corruption of green tide algae could also cause serious social problems. Consequently, we should salvage green tide algae as soon as possible for the hazard-free treatment, while the determination of green tide algae nutrients and the evaluation of their resource utilization safety were vital to the hazard-free treatment of“green tide”disaster. The green tide algae had a lot of economic seaweeds rich in nutrients and also possessed edible and medicinal value, they could be used to process into food products and so on, for the sake of changing waste into treasure、turning harm into good.The basic nutrients、chlorophyll、mineral elements and heavy metals of green tide algae collected from Zhejiang、Jiangsu、Shandong in 2009 were determined and analyzed by routine methods in this experiment. The results indicated that the contents of crude protein and chlorophyll varied wildly, the crude protein contents varied from 26.60% to 6.34% and the chlorophyll contents from 11.027mg/g to 0.707mg/g, both contents decreased significantly with the collection dates postponed; carbohydrate was the main nutritional composition of green tide algae, accounting for 40.49%~63.08%; the fat contents were relatively low, all the samples except Zhejiang xiangshan (1.03%) were less than 1%; the contents of mineral elements Ca、Fe、Zn were abundant; but the heavy metals Pb、As、Hg and Cd were all lower than the limited requirements in national standards. The basic nutrients、chlorophyll、amino acids、mineral elements and heavy metals of green algae collected from Jiangsu and Shandong in 2010 were analyzed and the results indicated that: carbohydrates were the main nutritional components of these green tide algae, accounting for 35.82%-52.43%; the crude protein contents varied greatly, from 31.04% to 12.11%; the fat contents were low and all less than 1%; there was a significant difference on the contents of chlorophyll, the contents decreased significantly with the collection dates delayed; the amino acid contents were high and the percent of essential amino acids were up to 37.45%, the flavor amino acids aspartic acid、glutamic acid、glycine and alanine were considerably high; these algae contained abundant mineral elements, the contents of Ca、Fe、Zn were distinctly high, but the heavy metals Pb、As、Hg and Cd were all lower than the limited requirements in national standards. In a word, the experiment results showed that the quality of green tide algae declined rapidly in the course of drift, the results could provide the theoretical basis for the comprehensive development and utilization of the green tide algae.This study used HPLC-HG-AFS and DDC-Ag to respectively detect the contents of inorganic arsenic in the green tide algae, and the results showed little difference between the two methods. HPLC-HG-AFS was a new method improved from the first method HG-AFS in the national standard GB/T 5009.11-2003. Using the HG-AFS method to detect inorganic arsenic in seaweeds, the extracted liquid from algae samples contained DMA, which was the decomposing product of arsenic sugar after pretreatment by HG-AFS method. DMA would produce the same signal as that produced by inorganic arsenic when detecting by AFS. The signal would disturb the final result heavily and lead to the result severe high. HPLC-HG-AFS used SA-10 morphological analysis to determine the samples of seaweeds after the preparation, not only could measure the total inorganic arsenic but also could detect trivalent arsenic and pentavalent arsenic respectively. By comparing HPLC-HG-AFS with DDC-Ag, the measured results showed that HPLC-HG-AFS could overcome the shortage of HG-AFS and obtain more accurate quantitative analysis on inorganic arsenic of the marine algae.At present, domestic research about the green tide algae mostly focused on molecular identification、life history、tissue culture and ecological characteristics and so on. As to the nutrition analysis of green tide algae, we made preliminary progress, but they focused on one specific location or one sea area about the green tide algae components analysis. When it came to the change of components about the green tide algae from the early period to the late period of“green tide”outbreak, especially the quality of the green tide algae in the course of drift, related research had not been reported. And it was very important for the comprehensive development and utilization of the green tide algae. In this study, the basic nutrients、amino acids、mineral elements and heavy metals of green tide algae collected from the path of drift at different locations and collection time were measured, and their changing conditions were analyzed in order to provide the theoretical basis for the comprehensive development and utilization of the green tide algae.