| Chlorella pyrenoidosa has the advantages of high protein content,fast growth rate and heterotrophic culture.In order to develop new food ingredients and meet the demand for microalgae food.In this experiment,we used Chlorella pyrenoidosa as the experimental object,replaced non-food ingredients in the culture medium with food-grade ingredients,optimized the culture medium,obtained a protein nucleus Chlorella pyrenoidosa medium composed of food-grade ingredients,and used the culture tank to figure out the conditions for pilot production.The results of the study are as follows:(1)Determination of basic culture conditions of Chlorella pyrenoidosa.The correlation equation between cell number and absorbance of Chlorella pyrenoidosa at680 nm was established by blood cell counting and spectrophotometry,which was y=16.337x-0.0248 R~2=0.9976(x is absorbance,ranging from 0.05 to 0.98;y is the number of cells,the unit is 10~9cells/L);By comparing three media such as BG11,the results showed that BG11 medium is more suitable as a base medium for algal species.Taking the biomass of Chlorella pyrenoidosa as the evaluation standard,through the screening of single factor experiments(temperature,light intensity and p H value),the temperature of 25?,light intensity of 11000 Lx and p H value of 7.1 were determined as the basic culture factors of Chlorella pyrenoidosa.(2)Optimal ratio of edible Chlorella pyrenoidosa culture medium.By selecting food-grade raw materials instead of non-food raw materials,taking the biomass of Chlorella pyrenoidosa as the evaluation standard,the monopotassium phosphate,sodium acetate and nutritional fortifier were tested by single factor experiment,and the edible Chlorella pyrenoidosa culture medium was obtained by optimization of response surface experiment.The medium composition was 0.5 g sodium nitrate,0.044 g dipotassium hydrogen phosphate,0.075 g magnesium sulfate,0.036 g calcium chloride,0.006 g ferric ammonium citrate,0.001 g EDTA,1.673 g sodium acetate,2.23?g manganese sulfate,0.22?g zinc sulfate,0.08?g copper sulfate,1.42 m L nutrient fortification per liter of medium,flowed with 2 g L-alanine as nitrogen source and 20 g glucose as carbon source.(3)Quality analysis of Chlorella pyrenoidosa.The Chlorella pyrenoidosa obtained after optimizing the culture medium was tested.The results of protein 59.27g/100g,water 4.31 g/100g,ash 4.54 g/100g,chlorophyll 45.78 mg/g,lead<0.1 mg/kg,arsenic<0.1 mg/kg,mercury not detected,cadmium not detected,Escherichia coli and pathogenic bacteria not detected showed that the obtained Chlorella pyrenoidosa met the relevant regulations and requirements.(4)Study on the culture conditions of Chlorella pyrenoidosa in pilot scale.Through the establishment of aseptic culture mode and the main culture factors(light intensity,ventilation rate and temperature)of 50 L culture tank were optimized,and the best environmental conditions of 50 L culture tank were determined:temperature25?,light intensity 10000 Lx and ventilation rate 300 h/L.The cultivation mode of Chlorella pyrenoidosa was established as photoautotrophic-facultative mode.Using the optimized culture medium,the maximum biomass per unit volume of 50 L culture tank could reach 29.53 g/L by feeding.Scale-up test of 2 T culture tank was carried out,adding sterilized carbon source and nitrogen source.After a period of culture,the biomass of 2 T culture tank could reach 30.25 g/L at the highest,and there was no significant difference between the biomass of 50 L and 2 T culture tank(P>0.05),and the scale-up effect was good.This experiment optimized the medium based on BG11 medium and scaled up the test in 50 L,2 T culture jars,and obtained better results.The safety of the product was enhanced due to the elimination of potentially harmful medium components as well as the reduction of certain potentially harmful ingredients,while ensuring the quality,and also enhanced the friendliness with the environment,so that the safety of microalgae food was valued.This experiment can provide a theoretical basis for the food-grade production of microalgae. |
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