# Antioxidant and Antimicrobial Activity of Porcine Liver Hydrolyates Using Flavourzyme
###### Abstract  
C oxidative stress is implicated in human diseases including cancer or neurodegenerative diseases. On the other hand, lipid and microbial spoilage are the main issues of food degradation. Bioactive peptides with antioxidant and antimicrobial activity could solve both problems and create an opportunity to improve the sustainability of the meat industry. Recently, meat by-products are subject of numerous studies to produce antioxidant peptides, highlighting pork liver as a potential source of hydrolyses. To achieve this purpose, pork liver was digested with Flavourzyme at four reaction times (4, 6, 8, and 10 h) and filtered with cut-offs of 5, 10, and 30-kDa molecular weight. Monitoring hydrolysis with SDS-PAGE showed that the reaction was almost complete. Free amino acid profile exhibited that aliphatic and aromatic amino acids were released in a higher amount at longer reaction times. Heat map analysis demonstrated that a hydrolysis time beyond 6 h, displayed a differential amino acid pattern enabling us to optimize the enzymatic reaction. Antioxidant activity was assessed using ABTS, DPPH, FRAP, and ORAC tests, while antimicrobial assay was carried out against Gram-positive and Gram-negative. ABTS and DPPH values revealed that hydrolyses showed a high antioxidant capacity, as well as an inhibition of growth of _Brochotrix thermosphata_ particularly 30 kDa hydrolysates. meat by-products; Flavourzyme; antioxidant activity; antimicrobial activity; free amino acids +
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molecules accumulated in a deficient antioxidant defense system leading to oxidative stress [2]. In this context, ROS are capable of damaging DNA, lipids, and proteins causing alterations in membrane properties (permeability and stability) and negatively affecting cellular function [3; 4; 5]. They also play a pivotal role in the release of cytochrome and apoptosis induction [6]. At the physiological level, oxidative stress has been associated with several chronic diseases including asthma, atherosclerosis, cancer, rheumatoid arthritis, stroke, allergic, cardiovascular, and kidney and neurological diseases [1; 7; 8]. However, ROS in adequate physiological concentrations are essential for homeostatic regulation and the immune system which uses them to attack and destroy pathogens [9; 10]. On the other hand, lipid and protein oxidation, as well as microbial growth, are the main problems of meat quality degradation [11; 12; 13]. Lipid oxidation is a non-microbial process of sensory and nutritional deterioration reducing the shelf-life of meat products [14]. The decrease of nutritional and sensory attributes mainly affects aroma profile, flavor, color, and texture. In this context, the development of a rancid odor results in a decrease of consumer acceptance [15]. To prevent the lipid oxidation, careful measures should be taken into account from the manipulation of the raw material (animal slaughter) to manufacturing, storage, and distribution [16]. Additionally, the oxidation process can be delayed by the action of antioxidants [17; 18; 19; 20]. Antioxidants can be useful as free radical scavengers due to their capability to stabilize or deactivate the radicals, hence they should be introduced as preservatives compounds in foods [21]. Antioxidant peptides could be used as natural preservatives as well as health-promoting molecules, controlling the oxidation in the human body. Bioactive peptides can be employed as nutraceutical ingredients in foods and pharmaceuticals. Therefore, the interest of consumers in these healthy products is increasing in recent years [22]. The bioactivity of the peptides (antioxidant, antimicrobial, antithrombotic, anticancer, or antihypertensive activity) is mainly defined by amino acid sequence [23]. Bioactive peptides with antioxidant activity can be generated from protein rich meat by-products [24]. Moreover, the re-use of these low-value products can mitigate the environmental and economic problems occasioned by the meat industry.