Lactic acid demineralization of green crab (Carcinus maenas) shells: effect of reaction conditions and isolation of an unusual calcium complex

Chitin and chitosan are potentially useful and environmentally friendly biopolymers with a wide range of value-added applications. Effective and green technologies for isolation of these materials are potentially important. Here, we report the use of lactic acid for the demineralization of green crab shells. Green crab shells and lactic acid, produced during cheese making, are two waste streams that could be tapped for large-scale chitin and chitosan processing. We have studied the effect of concentration and temperature on the demineralization of green crab shells. An unusual calcium lactate/lactic acid complex was also isolated and crystallographically characterized. The results have implications not only for the use of weak acids in the isolation of chitin and chitosan but also for the use of lactic acid as a solvent in green chemistry.

甲壳素（Chitin）与壳聚糖（chitosan）是兼具应用潜力与环境友好特性的生物聚合物，拥有丰富的高附加值应用场景。针对这类材料的高效绿色提取技术具有重要的应用价值。本研究采用乳酸（lactic acid）开展青蟹壳的脱矿处理研究，奶酪生产过程中产生的青蟹壳与乳酸均为废弃物流，可用于规模化的甲壳素与壳聚糖制备流程。本研究探究了浓度与温度对青蟹壳脱矿过程的影响，并分离得到一种特殊的乳酸钙/乳酸复合物，同时对其进行了晶体学表征。本研究结果不仅为弱酸法提取甲壳素与壳聚糖提供了技术参考，同时也为绿色化学领域中以乳酸作为溶剂的应用拓展了思路。