EFFECT OF ELASTIN HYDROLYSATE ON BACTERIA AND SOME SENSORY TRAITS OF CHILLED GROUND BEEF

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INTRODUCTION
Meat and its products are distinguished by their high nutritional value and constitute a major source of the essential amino acids that the human body needs, in addition to being a source of vitamin B complex and some mineral elements such as iron (3).Because of the chemical and biological nature of meat, it is subject to spoilage during the storage period as a result of oxidation, spoilage, and bacterial contamination, which are among the factors that most affect the quality of meat (12,28).The increasing demand for meat has increased competition and encouraged the innovation of new methods in the meat industry, as the meat industry is focusing around the world on developing new manufacturing, production and processing methods to meet consumer demand (4).Many recent studies are largely directed towards discovering compounds that preserve meat from damage and spoilage.These are biologically active peptides from natural sources (32), the use of which can have a significant impact on the meat industry through their use in reducing spoilage resulting from microorganisms.It acts as an antibacterial, in addition to improving the sensory qualities of meat such as tenderness, juiciness, flavor and general acceptability.Likewise, adding biologically active compounds to raw meat during meat processing and meat products has a positive effect on the meat and thus on the health of the consumer (15).Bioactive peptides can be classified into antimicrobial, anticancer, antithrombotic, antihypertensive, immuneenhancing, mineral-binding, and antioxidant (39).Many peptides produced from fermentation and enzyme-induced hydrolysis have shown physiological benefits in humans (8).Bioactive peptides can also be produced from meat proteins and then incorporated into meat products to improve the functional properties of meat products (9).Therefore, the meat industry relies heavily on methods that work to improve the quality and safety of products, such as improving taste, flavor, and texture, reducing fat and salt content, and packaging techniques (42).This study aims to prolong the shelf life of meat, reduce the number of bacteria, improve tenderness, flavor, and juiciness, and increase acceptability General.

Elastin hydrolysates are produced by the enzymes elastase (E.H.E), collagenase (E.H.C), trypsin (E.H.T), and pepsin (E.H.P).
According to the method described by (30, 41) the antibacterial activity was measured according to the method described by Hussein (26).Locally isolated bacterial strains E-coli and Staphylococcus aureus were obtained from the Department of Food Sciences/College of Agricultural Engineering Sciences/University of Baghdad with some modifications.The bacterial strains used were activated by taking cultures of the bacterial strains and injecting them into tubes containing TSB medium and incubating them at 37°C for 24 h, and the total number of bacteria was counted using the molded plate method after incubation.Bacterial growth was confirmed using TSA soy agar medium (25).Brain Heart Infusion BHI agar was prepared and poured into sterile Petri dishes and left to solidify.These bacteria were then wiped onto the media using sterile cotton swabs, and filter paper discs (0.5 cm in diameter) were placed.Soaked with 40, 30, 20, and 10 μl of elastin hydrolysate (until saturation), placed on the surface of the dish, and incubated at 37°C for 24 h (26).The diameters of the zones free of bacterial growth were measured (18).The activity of elastin hydrolysates and the size of the inhibition halo formed against E. coli and staphylococci were compared to the difference between the diameter of the zone of inhibition (clear zone) and the diameter of the disc after 24 hours.As for the number of bacteria in the addition treatments, the total number of bacteria in the meat samples was calculated using the Robert and Greenwood method (35).Total Plate Count, total psychrophilic count of bacteria was determined according to the method mentioned by Andrew (13).And E.coli bacteria using the Prince method (23).Sensory evaluation scores for flavor, tenderness, juiciness and general acceptability were also calculated for meat samples prepared for sensory evaluation by cooking them in an electric oven at a temperature of 165°C until the internal temperature of the meat reached 70°C (19).SAS statistical analysis software was used to analyze the data according to a completely randomized design (CRD), and significant differences between means were compared using Duncan's multinomial test (22).

E.coli
and Staphylococcus bacteria, respectively.Also, the concentrations of the rest of the elastin hydrolysates inhibited the numbers of bacteria in a varying manner, which explains the ability of elastin hydrolysates to inhibit These two types of bacteria, as well as collagenase (E.H.C), trypsin (E.H.T), and pepsin (E.H.P) E.coli, had a clear inhibition at high concentrations on E.coli and Staphylococcus bacteria, also, the inhibition of (E.H.E) was superior to other degraders.This is consistent with Pereira, et al (33).who indicated the ability of elastin peptides to inhibit Staphylococcus aureus and E.coli bacteria.Some studies also indicated that biologically active peptides produced from animal sources are considered to have anti-E.coliand Staphylococcus activity, as studies have indicated.The decomposers produced from pepsin possess antibacterial activity, and when monitoring the antibacterial ability of these decomposers, a decrease in the growth of Escherichia coli and Staphylococcus aureus bacteria, respectively, was observed (46).These results are also consistent with the findings of Theolier (29,43).. Effect of elastin hydrolysates added to ground beef stored in cold storage on bacteria: Chart (1) shows the effect of elastin hydrolysates added to fresh, chilled minced beef on Total psychrophilic count, E.coli bacteria, and Total Plate Count, as it was observed that there was a significant increase (P<0.01) in the number of bacteria for T 1 6.67, 3.05, and 8.15 CFU/gm meat in TBC4, E.coli, and TBC37, respectively, while elastin hydrolysates reduced the number of bacteria, especially with the T 2 and T 3 treatments, as the number of bacteria in T 2 reached 4.86, 2.34, and 5.58, and T 3 reached 5.21, 2.55, and 5.83 CFU/gm.meat for TPC4, E.coli, and TPC37 bacteria, respectively.The reason for the decrease in bacterial numbers is due to the effectiveness of antioxidant elastin hydrolysates in preventing the decomposition of both protein and fat and thus reducing oxidative stress due to microorganisms.Di Bernardini, et al (11,21,40).This is consistent with Alrubeii and Alalaq (8,10), who indicated the effect of using Lactobacillus plantarum as a preservation agent in reducing the number of bacteria in basturma.Made from buffalo meat and also consistent with the results of the study of Araújo et al (14).Who indicated that the use of essential oils and niacin in meat sausages reduces the microbial load.It agrees with Uma and Ravi (43).who studied the effectiveness of some carotenoids extracted from shrimp shells, which showed antibacterial activity, especially Bacillus sp, Achromobacter sp.As for the effect of periods, chart (2) shows a significant increase (P < 0.01) in the logarithm of the total number of bacteria in the periods of 12, 9, 6 and 3 days compared to the period of one day.The number of bacteria begins to increase as the cold storage period progresses and reaches its highest level in a period of 12 days, and this is consistent with the study of Hać-Szymańczu et al (24) and Naveena et al. (31).The action of elastin hydrolysates as antibacterial substances reduces the ability of bacteria to attach to surfaces and embed themselves in mucous membranes, as peptides showed antibacterial activity in the lactoferrin peptide by binding to lipopolysaccharides, purines and outer membrane proteins, as the antimicrobial activity leads to an acceleration of membrane permeability in E. coli (49).This agrees with Quintieri, who indicated that the effect of lactoferrin peptide hydrolysates resulting from digestion with pepsin prevents the growth of bacteria contaminating mozzarella cheese during cold storage Pseudomonas fragi, Pseudomonas gessardi, Serratia proteamaculans, Aeromonas salmonicida and Rahnella aquatilis (34).These results are also consistent with ahmed Al-Zubaidi (5).who indicated that adding extracts of antioxidants to ground beef stored refrigerated for different storage periods led to a decrease in the logarithm of total plate count, total psychrophilic count bacteria, and E.coli, compared to control treatments in ground beef and refrigerated stock.Chart 2. The effect of storage periods on the numbers of bacteria.Sensory evaluation of cold-stored ground bee: Table (1,2) shows the sensory evaluation scores (Tenderness, flavor, juiciness, general acceptability) for all treatments and for cold storage periods of 1, 3 and 6 days only.Days 9 and 12 were excluded for fear of high microbial content and to preserve the health of the assessors, as Table 1 shows the effect of adding the above-mentioned elastin hydrolysates on the sensory evaluation of ground beef stored in cold storage.The coefficients indicate a significant superiority (P<0.01) in the sensory evaluation scores (Tenderness, flavor, juiciness, and general acceptability) for T2, which recorded 44.5, 4.31, 4.09, and 4.52, and T3, which recorded 4.23, 3.98, 3.93, and 4.14.For tenderness, juiciness, flavor and overall acceptability, respectively.Compared with the control T1, which scored 3.34, 3.31, 3.35, and 3.47 in tenderness, juiciness, flavor, and overall acceptability, respectively.The reason for the high tenderness in the addition treatments is due to the high moisture content, the increased solubility of the meat protein, the ability of the meat to retain water, and the decrease in loss during cooking.As for the low tenderness in the control treatment, it is due to the high rate of loss during cooking, as the cooking process leads to the loss of fat and juices ,it also leads to shrinkage of the meat and thus a decrease in the tenderness of the meat (7)  While the increase in flavor levels in the addition treatments may be due to the effect of elastin hydrolysates on oxidation and microbial content compared to the control treatment, which recorded a significant decrease in sensory evaluation scores due to proteolysis, fat decomposition, and fatty acid production by increasing the duration of refrigerated storage, which causes unacceptable flavor and odors in the meat.The addition of elastin hydrolysates act as antioxidants, and antioxidants from natural sources delay rancidity and fat oxidation without any effect on sensory properties or nutritional value (47), which leads to preserving the quality of meat and prolonging its shelf life (2,9,37).The high degree of general acceptance in the addition treatments for elastin hydrolysates contributed to preserving the quality of the meat and reducing the damage caused by oxidation, proteolysis, microbial degradation, etc., as Abbas and Shakir indicated (1).It is noted that there is an increase in the degrees of general acceptance in the addition parameters, and this increase is due to the effect of elastin hydrolysates in preserving the quality of meat and reducing damage from oxidation, proteolysis, microbial degradation, etc., which leads to improving other characteristics, such as an increase in the percentage of tenderness and juiciness, and an improvement in flavor, and this is reflected in the general acceptance.Table (2) also shows the effect of the periods on the sensory evaluation scores of chilled ground beef, as it is noted that the degree of tenderness decreases in periods 1, 3, and 6, respectively .This decrease may be attributed to enzymatic hydrolysis that occurs in muscle tissue and protein degradation, and this degradation results from proteolytic enzymes such as calpains and cathepsins in addition to storage conditions and others (20,27).The effect of the cold storage period on the juiciness was significant (P<0.01), as the meat juiciness levels were highest during the 1 day period 3.85, while they gradually decreased as the storage periods progressed on days 3 and 6 (3.44 and 3.36), respectively.While the periods of cold storage showed a significant decrease in the degree of flavor in the period of 1, 3 and 6 days, respectively, the effect of the period of cold storage is evident in the significant decrease in the degrees of general acceptability, as it decreased significantly in the period of 6 days (3.50) compared to the period of one day ( 4.18 .) Adding collagen hydrolysates extracted from the skin of wild fish to minced meat stored for 10 days at a temperature of 4°C showed antioxidant activity.The improvement of the abovestudied characteristics, such as tenderness, juiciness and flavor improvement, was reflected in the general acceptance of the meat. .This is consistent with (8), who indicated the effect of using Lactobacillus plantarum as a preservative and antioxidant in improving the qualitative and sensory characteristics and prolonging the shelf life of pastarma made from buffalo meat.The use of antioxidants in the meat industry and In many applications, it has led to improving the quality and safety of products, such as improving taste, flavor, and texture, reducing the percentage of fat and salt in products, packaging techniques, and improving the pathogen detection system (6,38).The use of antioxidants in the meat industry and in many applications has led to improving the quality and safety of products, such as improving taste, flavor, and texture, reducing the percentage of fat and salt in products, packaging techniques, and improving the pathogen detection system (17,21,48).CONCLUSION From the results obtained from this study, it can be concluded that elastin hydrolysate possesses antimicrobial properties and has a high ability to inhibit bacteria, and that adding elastin hydrolysate to ground beef stored in refrigeration contributed to reducing the logarithm of the total number of bacteria in ground beef represented by Total Plate Count TPC37, Total psychrophilic count TPC4 Coldness, and spoilage E.coli bacteria.The decomposers also improved the sensory evaluation scores of chilled ground beef.

Figure 1 .
Figure 1.The effect of elastin hydrolysates on inhibiting bacteria : A-E. coli B-Staphylococcus bacteria RESULTS AND DISCUSSION Antibacterial activity of elastin hydrolysates Figure )1( shows the effect of elastin hydrolysates produced by elastase (E.H.E), collagenase (E.H.C), trypsin (E.H.T), and pepsin (E.H.P) in inhibiting E.coli and Staphylococcus bacteria.It is noted that the size of the corona resulting from the inhibition of (E.H.E) was clear at a concentration of 40 µl, as it reached 25 and 23 for each of the

Chart 1 .
The effect of adding elastin hydrolysates to ground beef stored in cold storage on the total psychrophilic count, E.coli bacteria, and the total plate count.

Table 1 . Effect of adding elastin hydrolysates to cold-stored ground beef on sensory evaluation scores ± SE
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