Blood is one of the main meat industry by-products, with an interesting nutritional value and functional properties. Although blood is a good and sustainable source of functional proteins, according to recent reports only a small fraction is directed for human consumption, since the main products where blood and its derivatives have been used are related to the pet food industry, being followed by the fertilizers industry1. The search for more sustainable protein sources raises the importance to develop effective strategies to increase blood valorization towards human nutrition. In this study, an innovative approach based on enzymatic hydrolysis and membrane technology system was developed. Swine blood was cooked and enzymatically hydrolyzed with Cynara cardunculus L., where 200 kg of cooked swine blood were processed with 300 kg of water. After the hydrolysis process, the product was filtered with a sieve (0.5 mm) and the resultant liquid fraction was submitted to microfiltration (MF), using a 0.2 µm pore size membrane. Subsequently, MF retentate (MFR) was submitted to reverse osmosis (RO) and freeze-dried. Nanofiltration (NF) with a 3 kDa cut-off membrane was then performed with the MF filtrate (MFF), being the resultant NF retentate fraction (NFR) subjected to RO and freeze-dried. A new sequential NF step was carried out with the NF filtrate, using a 120 g mol-1 cut-off membrane. The resultant retentate fraction (NF filtrate; NFF), was also subject to RO and lyophilized. The biological potential of MFR, NFR and NFF in both food and feed nutrition were investigated. The results suggested that all fractions had a high content of protein, possessing MFR and NFR approximately 90% of total protein, while NFF about 65% on a dry basis. The protein and peptide profile indicated that all hydrolysates showed a similar profile with peaks between 1200 and 14000 Da but, NFF had a greater concentration of lower molecular size peptides (<1200 Da). Regarding the antioxidant capacity, NFF showed higher antioxidant activity by both 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and oxygen-radical absorbance-capacity (ORAC) assays, with antioxidant values of 0.85±0.11 and 0.53±0.10 µM Trolox equivalent (TE)/mg of dry matter (DM), respectively, aligning with its peptide profile. NFR fraction had also an interesting antioxidant potential with ABTS and ORAC values of 0.45±0.01 and 0.45±0.03 µM TE/mg DM, respectively. Additionally, the anti-hypertensive activity was also tested and the results suggested that NFF showed an excellent anti-hypertensive potential namely, 28 µg/mL to inhibit 50% of the angiotensin-converting enzyme activity. According to their biological potentials, the hypothesis of MFR and NFR being used in aquaculture feed, while NFF as a food functional ingredient was raised. The MFR and NFR fractions were tested in juvenile European seabass and compared with standard commercial diets typically used in aquaculture. The results of NFR dietary supplementation were very promising, promoting fish robustness and improving resistance and survival to Tenacibaculum maritimum infection. High mortality rates often occur in marine aquaculture farms due to bacterial infections, particularly due to T. maritimum outbreaks that have usually been treated by antibiotics. The dietary inclusion of NFR hydrolysates is a very promising achievement in the improvement of European seabass to T. maritimum resistance without affecting the growth rate. Regarding the NFF fraction, the biological characterization was also complemented to clarify its potential for human nutrition. Free amino acids were identified and quantified, being the most incident glutamic acid, leucine, alanine, phenylalanine and aspartic acid, with concentrations between 109.85 and 190.60 mg/100 g. Also, mineral content was monitored with phosphorus, magnesium, calcium, sodium and potassium as the most important minerals. The antimicrobial potential was also tested but, no antimicrobial effect was verified for 7 pathogenic bacteria tested. The high protein content, antioxidant and anti-hypertensive capacities as well as the interesting mineral and free amino acid contents make NFF a fraction with high potential for functional ingredient in human nutrition. Thus, the present study represents a first step towards the development of a more sustainable protein source for human consumption. Overall, this approach corresponds to a new and effective way to produce two value-added blood hydrolysates for both human and fish nutrition that increase the economic value of swine blood and minimize waste, contributing to a circular economy approach.
| Period | 5 Sept 2021 |
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| Event title | XV Encontro de Química dos Alimentos: Estratégias para a Excelência, Autenticidade, Segurança e Sustentabilidade Alimentar |
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| Event type | Conference |
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| Location | Funchal, PortugalShow on map |
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