Effect of Calcium Chloride Treatment on the Accumulation of Calcium and Phenolics and the Estimation of Antioxidant Capacity in Germinated Quinoa

Background:Calcium (Ca2+) is an essential mineral element for the human body and plays an important regulatory role in plant growth. Germination is one of the biofortification methods for whole grains, enhancing the nutritional value and functional properties of cereals and significantly reducing antinutritional factors. During evolution, grains evolved to synthesize polyphenolic compounds as a defense mechanism against environmental stresses and for self-protection. However, there is a lack of research on calcium and polyphenol accumulation, as well as on antioxidant capacity, during quinoa germination in the presence of exogenous calcium chloride (CaCl2).Methods:This study systematically analyzed the accumulation of calcium and phenolics and evaluated the antioxidant capacity in germinated quinoa treated with exogenous CaCl2 at concentrations up to 60 mM.Results:The sprout lengths of quinoa in the 30–60 mM CaCl2 groups were significantly shorter (p < 0.05) than those of the control group (0 mM CaCl2). In the 40 mM treatment group, the nutrient reference value (NRV) was over 30% after 24 hours, and in the 50–60 mM treatment group, the NRV also exceeded 30%, meeting the standard of being rich in calcium. However, the total phenolic content (TPC) of calcium-rich germinated quinoa at 24 h in the 60 mM group was 7.65% lower compared with the control group. This indicates that high Ca2+ levels can reduce TPC in sprouted quinoa while enhancing calcium bioavailability. In the control group (0 mM), the phytic acid (PA) content after 24 h of germination was 2.45 ± 0.15 mg/g DW. The PA content and PA/Ca ratio in the exogenous calcium treatment groups were significantly lower compared with the control group (p < 0.05). The PA/Ca ratio in the 40 mM group (24 h) was significantly reduced by 97.33% compared with the control group, indicating that CaCl2 treatment can mitigate the inhibitory effect of PA on calcium absorption in germinated quinoa. Moreover, the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity in the exogenous CaCl2 groups was significantly increased compared with the control group (p < 0.05).Conclusions:This study provides useful data for the development of calcium-biofortified germinated quinoa with improved mineral bioavailability and antioxidant capacity.