Title : Effect of bioactive calcium chelated soy oligopeptides compare to calcium chelated corn oligopeptides
Abstract:
Among human needs, nutrition is priority. There are many people in the world whose diet are not meeting the recommended daily level of calcium, mainly the target group (children and their mothers, pregnant and nursing women, old women). Calcium plays an important function in the body, especially for bones and teeth, but its absorption from foods remains inefficient even though many foods contain sufficient amount of calcium. However, certain proteins and amino acids can stimulate calcium absorption (Martha. 1983). Among these, oligopeptides having chain length 2-10, preferably 3-6 derived from soy proteins. Oligopeptides are taken orally and is readily absorbed by the digestive tract (Minoru. 1988). The present research was undertaken to study the chelation of calcium to the oligopeptides prepared from soy and corn protein and their absorption by the digestive tract. Commercial defatted soy flour was solubilized in an aqueous solution at pH 9.0 to prepare a soy protein for enzymatic hydrolysis. Crude corn protein powder was directly hydrolyzed. Hydrolysis was carried out using an alcalase A/S Bagaswaerd, to prepare oligopeptides from either soy and corn protein, called soy protein hydrolysate (SPH) and corn protein hydrolysate (CPH) respectively, at higher degree of hydrolysis (DH). The initial defatted soy flour and crude corn protein concentration was set at 15% and 10% respectively. The temperature was 50o C, alcalase substrate ratio 2%, pH 9.0, hydrolysis time 12 hours. Following hydrolysis, 56.04% and 47.8% of protein was extracted respectively from SPH and CPH. Free amino groups, ash and moisture contents were also determined. High-performance liquid chromatography (HPLC) measurement showed a mixture of proteins, oligopeptides, and amino acids in SPH and CPH. 88.26% represented oligopeptides from SPH and had molecular weights of 281.11, 676.99 and 1219.98 Daltons; which correspond to dipeptides, pentapeptides and decapeptides. 73.01% represented oligopeptides from CPH with molecular weights of 413.66 and 288.96 Daltons, which corresponded to dipeptides and tripeptides. Binding was carried out by using 0.1 mole/L of CaCl2 (ratio hydrolysates to CaCl2 solution 1:1) at 60o C and pH was adjusted (6.0 to 7.5). Calcium bound to the oligopeptides was obtained by alcohol precipitation and without alcohol precipitation. Alcohol precipitation yielded a higher percentage of chelated calcium to soy and corn oligopeptides, named calcium chelated soy oligopeptides (CCSO) and calcium chelated corn oligopeptides (CCCO) respectively (Aboubacar. 2024). Chelated calcium was collected in the precipitate with alcohol precipitation respectively 32.22 % and 37.57% for CCSO and CCCO.
The effect of pH on oligopeptides affinity for Ca2+ was investigated. Bitter taste has been eliminated for both CCSO and CCCO. The color of both products CCSO and CCCO was also improved. Both methods AAS and ISEPM were carried out to evaluate the amount of chelated calcium in CCSO and CCCO. The absorption and retention rate of these complexed oligopeptides of calcium, indicated a satisfactory result. The consumption of these products is a good way for self-monitoring in order to find a solution to control calcium deficiency diseases.
Keywords: Enzymatic hydrolysis, soy oligopeptides, corn oligopeptides, calcium binding, calcium chelated, Calcium deficiency diseases.
