Optimisation of the Enzymatic Hydrolysis of Blood Cells with a Neutral Protease

Abstract

For utilizing the blood cells (BCs) effectively, enzymatic hydrolysis was applied to produce the enzymatically hydrolyzed blood cells (EHBCs) by using a neutral protease as a catalyst. The results of the single-factor experiments showed optimal substrate concentration, enzyme to substrate ratio (E/S), pH, temperature, and incubation period were 1.00%, 0.10, 7.00, 50.00°C, and 12.00 h, respectively. The optimized hydrolysis conditions from response surface methodology (RSM) were pH 6.50, E/S 0.11, temperature 45.00°C, and incubation period 12.00 h. Under these conditions (substrate concentration 1.00%), the degree of hydrolysis (DH) was 35.06%. The free amino acids (FAAs) content of the EHBCs (35.24%) was 40.46 times higher than BCs while the total amino acids (TAAs) content was lower than BCs. The scores of lysine (human 0.87; pig 0.97), valine (human 1.42; pig 1.38), leucine (human 1.50; pig 1.90), tyrosine (human 0.84; pig 1.09), and histidine (human 2.17; pig 2.50) indicated that the EHBCs basically fulfilled the adult human and pig nutritional requirements. The calculated protein efficiency ratios (C-PERs) of the EHBCs were 3.94, 6.19, 21.73, and 2.04. In summary, the EHBCs were produced successfully with optimized conditions and could be a novel protein source for humans and pigs.

Neutral protease expression and optimized conditions for the degradation of blood cells using recombinant Pichia pastoris

“…These results indicate a high degree of correlation between the experimental and predicted values. Good correlations between the experimental results and the results predicted by RSM models of proteolytic reactions have been reported by several researchers (Chen et al, 2010;P erez-G alvez et al, 2011;Zheng et al, 2012). The very low value of the coefficient of variation (C.V.) (1.84% for pGAPZaA-NpI-GS115) clearly indicates the very high degree of precision and reliability of the experimental values.…”

“…Under the abovementioned conditions, the experimental DH of fermented blood cells with pGAPZaA-NpI-GS115 is 49.05%, which is much higher than 35.13% and 32.91% that reported by Zheng et al (2012Zheng et al ( , 2014, respectively. …”

“…However the low digestibility and metallic taste of hemoglobin (Hb) are not desirable when BCs are added to a variety of food and feed products (Toldr a et al, 2011). To solve these problems, various attempts (e.g., microbial fermentation) have been made to process BCs, especially by breaking the blood cell membrane to improve the availability of BCs (P erez-G alvez et al, 2011;Zheng et al, 2012). After being processed, complex molecules, such as macromolecular proteins, are degraded into peptides of various molecular weights and free amino acids (FAAs) (Par es i Oliva, 2001;Gaskell and Smith, 2007;Guo et al, 2007).…”

Optimization of Parameters that Affect the Activity of the Alkaline Protease from Halotolerant Bacterium, Bacillus acquimaris VITP4, by the Application of Response Surface Methodology and Evaluation of the Storage Stability of the Enzyme

“…JER02 with statistical optimization by RSM. The RSM was also employed for optimizing conditions for enzymatic hydrolysis of the blood cells wherein a 40.46 times increase in the production of the free amino acids was achieved (27). Using a two-step response surface methodology (RSM), the condition for an optimum keratinase activity was optimized (28).…”

Effect of fermented blood cells on growth performance and intestinal characteristics of weaned piglets

“…To improve the availability of blood meal, various attempts (e.g. ferment) have been made to process the blood meal (Pérez-Gálvez, Almécija, Espejo, Guadix, & Guadix, 2011;Zheng, Chen, Shan, & Zhang, 2012). After fermenting, the digestibility of the protein is improved and the product absorbs easily (Gaskell & Smith, 2007;Guo, Zhao, Wang, & Cui, 2010).…”