A Novel Low Molecule Peptides-calcium Chelate from Silkworm Pupae Protein Hydrolysate: Preparation, Antioxidant Activity, and Bioavailability.

BACKGROUND: The antioxidant properties of active peptides from silkworm pupae protein hydrolysate are of interest, and it serves as a novel source of calcium supplement. METHODS: Optimize the preparation parameters of silkworm pupae bioactive peptide-calcium chelate, and investigate the mechanism and bioavailability of silkworm pupae active peptide as a transport carrier to promote calcium ion absorption using simulated gastrointestinal digestion and Caco-2 monolayer cell model. RESULTS: The optimal process parameters for preparing peptide calcium chelate were the peptide calcium mass ratio of 3:1, pH of 6.7, a temperature of 35.6°C, and time of 32.8 min by Box-Behnken design, and the calciumchelating rate reached 84.67%. The DPPH radical scavenging activity of silkworm pupae protein hydrolysatecalcium chelate was 79.36 ± 4.31%, significantly higher than silkworm pupae protein hydrolysate (61.00 ± 9.56%). Fourier transform infrared spectroscopy shows that the COO-, N-H, C-H, and C-O groups participated in the formation of silkworm pupae protein hydrolysate-calcium chelate. The particle size of the silkworm pupae protein hydrolysate-calcium chelate was 970.75 ± 30.12 nm, which was significantly higher than that of silkworm pupae protein hydrolysate (253.14 ± 5.72 nm). The silkworm pupae protein hydrolysate-calcium chelate showed a calcium dissolution rate of 71.01 ± 1.91% in the simulated intestinal phase, significantly higher than that of CaCl2 (59.34 ± 1.24%). In the Caco-2 cell monolayers, the silkworm pupae protein hydrolysatecalcium chelate was more favorable for calcium transport. CONCLUSION: A novel silkworm pupa protein hydrolysate-calcium chelate with high antioxidant activity was successfully prepared to improve the bioavailability of calcium.

Viewing DVM via general behaviors of zooplankton: a way bridging the success of individual and population.

In this paper, we viewed the diel vertical migration (DVM) of copepod in the context of the animal's immediate behaviors of everyday concerns and constructed an instantaneous behavioral criterion effective for DVM and non-DVM behaviors. This criterion employed the function of 'venturous revenue' (VR), which is the product of the food intake and probability of the survival, to evaluate the gains and losses of the behaviors that the copepod could trade-off. The optimal behaviors are to find the optimal habitats to maximize VR. Two types of VRs are formulated and tested by the theoretical analysis and simulations. The sensed VR, monitoring the real-time changes of trade-offs and thereby determining the optimum habitat, is validated to be the effective objective function for the optimization of the behavior; whereas, the realized VR, quantifying the actual profit obtained by an optimal copepod in the sensed-VR-determined habitat, defines the life history of a specific age cohort. The achievement of a robust copepod overwintering stock through integrating the dynamics of the constituent age cohorts subjected to the instantaneous behavioral criterion for DVM clearly exemplified a possible way bridging the immediate pursuit of an individual and the end success of the population.