| As the toxicity of synthetic pigments has come to light,countries around the world decrease the use of synthetic pigments.Natural food pigments were welcomed by the consumers because of their high safety.Quantity and varieties of natural pigments in many countries have far exceeded the allowable synthetic pigments.Natural pigments with high safety,renewable resources,less environmental pollution etc meet the requirements of development trend in the world today.To keep with international standards and further protect the health of people,China also need to develop natural pigments,especially some natural pigment varieties with high safety,strong tinting strength,stability,and reasonable price.Natural pigment’s development will provide safe and reliable raw materials for the food industry in China.As the same time it adds more color and safety in Chinese food.With the development of science and technology,development and utilization of edible natural pigments is bound to have a good future.In this article,the system technology on the production of Roselle anthocyanin was studied including raw material preservation,extraction,separation and purification of anthocyanin,vacuum freeze drying etc.The main results are as follows:1.The study on anthocyanin contents in different varieties(early-mature pink,medium mature purple and Late-mature purple)and different treatments by the pH differential method showed that the anthocyanin contents were Late-mature purple>medium mature purple>early-mature pink.In fresh Roselle,anthocyanin content of final purified product were respectively 55.47mg/g、52.98mg/g and 45.89mg/g;in heat-pump dehydrated Roselle,respectively 47.94mg/g、46.16mg/g and 42.65mg/g;in sun-light dehydrated Roselle,respectively 42.38mg/g、42.78mg/g and 21.67mg/g;in frozen fresh Roselle,respectively 40.04mg/g、40.39mg/g and 40.11mg/g;in cold-stored fresh Roselle,respectively 47.92mg/g、44.15mg/g and 39.54mg/g.Then,Late-mature purple Roselle of heat-pump dehydrated was used in industrial production and the anthocyanins of Roselle was high yield and low cost.2.The single factor parallel experiment was made,including extraction solvent、extraction temperature、extraction time、solvent concentration and rate of solid to liquid.In order to optimize the craft condition,the orthogonal experiment for four levels and three factors was carried on.The optimal process condition for the extraction of Roselle anthocyanin:extraction temperature of 60℃,reaction time of 90mins,materials to liquid of 1:15,citric acid concentration 0.1M.In the experiment under these conditions,the anthocyanin content was 5.586mg/g powder.3.The study of single factors and integrated analysis on ultra-filtration and nano-filtration showed that the best membrane combination in separation and purification of Roselle pigment was UH100 ultra-filtration membrane and NS027 nano-filtration membrane,operation pressure respectively was 0.4MPa and 1.5MPa,and operation temperature respectively is 30 ℃-35 ℃ and 40 ℃,which had higher extraction rate and the anthocyanin content of product was up to 32.7mg/g.In the comparison experiment of spray drying and vacuum freeze drying,the anthocyanin content of product by vacuum freeze drying was 14.7mg/g more than that by spray drying.Vacuum freeze drying can effectively reduce 43.4%the loss of anthocyanins,and increase the purity of the product.4.The HPLC conditions for Roselle anthocyanins:Chromatographic column is Jiangsu Hanbang lichrospher5-C18 column(150mmx4.6mm,5um),flow phase A is 100%chromatographic acetonitrile,flow phase B is 0.1%phosphate water solution,flow phase B reduced from 90%linear to 87%within 15min;the volume flow is lml/min;detection wavelength 520nm;column temperature 35 ℃;sample volume:10μl.Cyanidin-3-O-glucoside chloride is standard sample.The determination results were that the anthocyanin contents in different varieties(early-mature pink,medium mature purple and Late-mature purple)of Roselle were respectively 7.41mg/g、7.82mg/g and 8.85mg/g powder. |
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