Development of effective technologies for extraction of organic calcium from arctic shrimp processing waste

Introduction. Calcium is a key macroelement that ensures bone mineral density, muscle and cardiovascular function, and is involved in enzymatic and neurotransmitter processes. Calcium deficiency is widespread and associated with the development of osteoporosis and other metabolic disorders. The administration of medicinal preparations with calcium compensates its deficiency in patients and contribute to disease prevention and treatment. In the context of sustainable development, there is growing interest in new technologies for isolating organic calcium salts from marine bioresources for medicinal use. Aim. To develop and compare technologies for extraction of organic calcium from the shells of Arctic shrimp Pandalus borealis (a waste of food industry), and to evaluate the composition and purity of the obtained products. Materials and methods. The shells of cooked-frozen Arctic shrimps Pandalus borealis were processed by two calcium extraction technologies: (1) direct demineralization with organic acids (citric, malic and lactic) and (2) preliminary defatting of the raw material with ethanol followed by demineralization. Quantitative analysis of calcium (Ca) and other elements was performed by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). A hazard quotient (HQ) was calculated for safety assessments. Results and discussion. It was found that the maximum calcium yield was achieved after demineralization with citric acid (153.0 ± 10.3 mg Ca/g). Malic and lactic acids showed less efficiency. Preliminary defatting reduced the Ca yield by an average of 2.2 %; however, the lipid fraction is of interest as a source of carotenoids and other natural lipids. Toxic elements (Pb, Cd, Ni, Cr, As) were either not detected or their concentrations were below the limit of quantification. The content of associated elements (Mg, Zn, Fe, Cu, and Mn) was below the toxic level (calculated HQ < 1). Consumption of isolated Ca products will provide enrichment of the dietary intake with certain microelements. Conclusion. The shells of Arctic shrimps are a valuable source of organic calcium for the environmentally friendly production of physiologically balanced calcium salts – calcium citrate, malate, and lactate. The resulting calcium salts are not polluted with toxic elements and can be used in the pharmaceutical and food industries.