蛋白核小球藻浓缩制品低温保藏技术研究

Evaluation of Cryopreservation Technology for ConcentratedProducts of Cholorella pyrenoidosa

中文关键词: 蛋白核小球藻  浓缩制品  低温保藏  细胞活力  营养品质

英文关键词: Chlorella pyrenoidosa  Concentrated products  Cryopreservation  Cell viability  Nutritional quality

中文摘要:

      本研究以离心和重悬工艺获得的蛋白核小球藻(Chlorella pyrenoidosa)浓缩藻膏(8× 1010 cells/mL)和浓缩藻液(1×108 cells/mL)为研究对象，系统评价了巴氏杀菌以及保藏温度[室温(25℃)和4℃]对短期避光保藏下细胞相对活性和营养保持率的影响。结果显示，巴氏杀菌处理会引起2种蛋白核小球藻浓缩制品褐变，室温保藏会加速其腐败。浓缩制品可在4℃低温下直接保藏15 d，浓缩藻膏中总叶绿素、总类胡萝卜素和蛋白质含量分别为保藏前的97.20%、100.00%和98.20%；浓缩藻液中总叶绿素、总类胡萝卜素和蛋白质含量无变化，均与保藏前的含量相同。本研究还建立了荧光探针法检测蛋白核小球藻细胞活性的最优条件：细胞浓度为2.6×105 cells/mL，二醋酸荧光素工作浓度为60 μmoL/L，染色时间为30 min。结果显示，4℃条件下直接保藏15 d后，浓缩藻膏和浓缩藻液的细胞相对活性分别为保藏前的48.26%和61.36%。本研究建立的蛋白核小球藻浓缩制品的低温保藏技术，为微藻新鲜浓缩制品的下游水产应用提供了重要技术支撑。

英文摘要:

      Chlorella pyrenoidosa is widely used in aquaculture as a living food, water adjusting agent, and functional feed additive. It is thus important to study the methods of effectively maintaining cell activity and nutritional quality, and extending shelf life in the concentrated products of C. pyrenoidosa. At present, the commonly used preservation method for microalgae is cryopreservation. In this study, we used concentrated algal paste (8×1010 cells/mL) and concentrated algal fluid (1×108 cells/mL) of C. pyrenoidosa prepared by centrifugation and resuspension as the research objects, and systematically evaluated the effects of pasteurization and temperature (25℃ and 4℃) on the relative cell activity and nutrient retention rates under short-term storage without light exposure. Our results showed that pasteurization treatment caused the browning of both C. pyrenoidosa concentrates, and storage at room temperature accelerated the decay of concentrated products. Thus, the concentrated products could be stored directly at a low temperature of 4℃ for 15 days without pasteurization treatment. The total chlorophyll, carotenoids, and protein content in the concentrated C. pyrenoidosa paste reached 97.20%, 100.00%, and 98.20% of the levels before preservation, respectively; in the concentrated C. pyrenoidosa fluid all levels were 100.00% of those before preservation. This study also established the optimal conditions of the fluorescent probe method for cell viability detection: cell density of 2.6×105 cells/mL, working concentration of 60 μmol/L of fluorescein diacetate, and staining time of 30 min. The results indicated that the relative cell viability of the concentrated C. pyrenoidosa paste and fluid directly stored at 4℃ were 48.26% and 61.36%, respectively, before preservation. The cryopreservation technology established in this study for the concentrated products of C. pyrenoidosa provides a critical technology support for the downstream aquaculture applications of fresh concentrated products of microalgae.