Influence of Preparation and Isolation Methods on the Measurement of Calcium Levels in Dried Freshwater Shrimp (Macrobrachium sp.)

In Indonesia, shrimp are an important natural resource. They are easily obtained and are assumed to contain high levels of calcium. This research aims to determine the calcium levels in Macrobrachium sp. as well as the effects of preparation and isolation methods on such measurements. Ebi shrimp were divided into two preparation groups: oven-dried and nonheated. Oven drying was performed at 80°C for 20 min. The samples in each preparation group were divided according to three isolation methods: dilution, acid digestion, and dry ashing. In the dilution method, a sample was shaken in demineralized water. The acid digestion method used microwave-assisted digestion with nitric acid and hydrogen peroxide. In the dry ashing method, a sample was heated from 26°C to 550°C to produce ash before nitric acid and hydrochloric acid were added. Measurements were performed using atomic absorption spectrometry and an ion-selective electrode. The results showed that the highest calcium levels were obtained by acid digestion isolation: 7749 ppm (oven-dried) and 8853 ppm (nonheated). There were differences in the calcium level between the preparation methods and among the isolation methods. The preparation methods were found to have a strong correlation with calcium level measurement (r² = 0.878, p < 0.05).