Bioconversion of duck blood cell: process optimization of hydrolytic conditions and peptide hydrolysate characterization

Abstract

BackgroundAs the protein-laden by-product, red blood cells (RBCs) from poultry blood is a potential source of protein used as food and feed ingredient. However, RBC was currently underutilized. Therefore, it is an urgent need to develop feasible and cost-effective methods for converting poultry waste into nutritional and functional products.ResultsTo take full advantage of this poultry waste, peptide hydrolysate was produced by deep controllable bioconversion of RBC, by means of synergistic combination of neutrase and flavourzyme. In this work, the functional properties and antioxidant activity of peptide hydrolysate were also characterized. The degree of hydrolysis (DH) was optimized using response surface methodology, and optimal hydrolysis conditions were found to be: temperature 51 °C, substrate concentration 14% (w/v), initial pH 7.0, and time 7.5 h. The red blood cell hydrolysate (RBCH) obtained not only possessed plentiful small peptides (< 3 kDa, 68.14%), but also was abundant in essential amino acids, accounting for over 50% of total amino acids. In addition to its excellent solubility (> 80%), emulsifying and foaming properties, RBCH also exhibited notable antioxidant activities, such as DPPH (2,2-diphenyl− 1-picrylhydrazyl) radical-scavenging activity (IC50, 4.16 mg/mL), reducing power, metal chelating ability and inhibiting lipid peroxidation.ConclusionsRBCH enriched in small peptides has the potential to be a new food additive with outstanding functional and antioxidant properties, and a process was established for converting poultry waste into peptide hydrolysate using neutrase and flavourzyme.Electronic supplementary materialThe online version of this article (10.1186/s12896-018-0475-5) contains supplementary material, which is available to authorized users.

Investigation of optimal conditions for production of antioxidant peptides from duck blood plasma: response surface methodology

“…The amino acid composition of DBPH is shown in Table 4 . Duck blood plasma hydrolysate was found to be rich in Glu, Leu, Asp, Arg, and Lys, which was consistent with the main amino acids of duck blood of Sorapukdee and Narunatsopanon (2017) and Zheng et al. (2018b) .…”

“…Duck blood plasma was rich in Glu, Asp, Leu, and Lys, which is consistent with previous reports. Researchers ( Sorapukdee and Narunatsopanon, 2017 , Zheng et al., 2018b ) showed that these were the main amino acids in duck blood and blood cells. The amino acid composition was reasonable, and the ratio of essential amino acids (38.92%) was higher than the ideal protein value recommended by the Food and Agriculture Organization of the United Nations ( WHO, 2007 ).…”

“…As we all know, when the substrate protein is enough, more antioxidant peptides can be got by the increasing with the E/S ratio. However, when the ratio of E/S is too high, the antioxidant activity of the hydrolysates will be reduced with the increasing of the ratio of E/S because it might be attributed to the recleavage of antioxidative fractions or enzyme inhibition ( Zheng et al., 2018b ). Therefore, the optimum E/S ratio was 0.3%.…”

“…Response surface methodology ( RSM ) is a common and effective method to optimize hydrolysis. Response surface methodology has been widely applied in food research for process optimization ( Paseephol et al., 2007 ; Ren et al., 2008 ; Ye et al., 2018 ; Zheng et al., 2018b ). Therefore, the objective of this study was to establish optimal conditions for the hydrolysis of DBP to produce antioxidant peptides based on the 1,1-diphenyl-2-picrylhydrazyl ( DPPH ) radical-scavenging activity.…”

Using RSM for Optimum of Optimum Production of Peptides from Edible Bird’s Nest By-Product and Characterization of Its Antioxidant’s Properties

“…Peptides were re-digested with an increased hydrolysis time, leading to a decrease in DH [ 32 ]. In addition, the hydrolysate competed with the substrate for the active site of the enzyme, inhibiting the enzymatic hydrolysis reaction [ 33 ] and reducing DH. Therefore, the optimum hydrolysis time was 10 h.…”