The calcium carbonate (CaCO3) and calcium phosphate [Ca3(PO4)2] have been widely used as a calcium supplement in a range of processed food. Due to extremely low oral absorption of calcium-based food additives, they are typically modified into nano-s...
The calcium carbonate (CaCO3) and calcium phosphate [Ca3(PO4)2] have been widely used as a calcium supplement in a range of processed food. Due to extremely low oral absorption of calcium-based food additives, they are typically modified into nano-sized particle to increase its oral bioavailability. However, nano-sized particles have been under scrutiny, since its chemical and physical properties associated with toxicity are significantly different as compared to those of its bulk counterpart. Thus, it is important to monitor the size and physicochemical property of nano-sized calcium-based food additive to obtain critical information about the safety of these materials. However, the extraction of target materials from processed food is highly challenging due to the presence of complex food matrices, such as fats, proteins, and carbohydrates. Acid digestion is often employed to remove organic food matrices, but the harsh acid treatment in combination with heating at high temperature could alter the size and physicochemical characteristics of particles. In this study, we report a fast and highly selective separation method for the extraction of CaCO3 and Ca3(PO4)2 through starch magnetic beads (SMBs) functionalized with polystyrene sulfonate (PSS). The PSS@SMBs were shown to effectively bind to the calciumbased food additive, based on its specific affinity to calcium ion, in comparison with other type of inorganic ingredients, such as titanium dioxide (TiO2) and silicon
dioxide (SiO2). The bound particles were readily eluted from PSS@SMBs by addition of 0.1% polyethylenimine (PEI) that outcompetes calcium-based food additive for binding to the surface of PSS@SMBs. We demonstrated method affected neither the size nor crystallinity of the recovered calcium-based food additives as observed by SEM and XRD analysis, respectively. Moreover, we illustrated the feasibility of applying PSS@SMBs in specifically extracting CaCO3 and Ca3(PO4)2 from six commercial foods. The results suggest that the method developed in this study would provide an effective means of extracting calciumbased food additive from processed food to monitor and understand its physicochemical properties and safety.