Valorization of functional properties of extract and powder of olive leaves in raw and cooked minced beef meat

Acrylamide detection and reduction in meat products using organic acids, fruit extracts, and probiotics

Grilled foods are an important source of acrylamide, which has neurotoxic, genotoxic, and carcinogenic properties. The current study aims to evaluate the level of acrylamide in beef, chicken, and fish products, especially those requiring high cooking temperatures, using High Performance Liquid Chromatography (HPLC). Reduction of acrylamide by organic acids i.e., (citric acid, malic acid, tartaric acid, and lactic acid) and fruit extracts of lemon, apple, and grape has also been investigated. The results revealed that the highest mean acrylamide concentration was found in chicken products (grilled chicken) which recorded 8.32 μg/100 g, followed by beef products (beef grilled) with a concentration of 7.91 μg/100 g, and fish products (pan-fried fish burgers) which recorded 6.77 μg/100 g). Furthermore, the mixture of organic acid has the highest effect on reducing the level of acrylamide in a chemical model system. Moreover, the fruit extract mixture was more effective in reducing the percentage of acrylamide in the grilled chicken than organic acids mixture. Finally, the addition of fruit extract improved the sensory properties of grilled chickens. In sum, this study offers novel and promising natural strategies to decrease acrylamide in meat products toward further future application in meat industry to deliver safe food to consumers.

Pomegranate Peel and Olive Leaf Extracts to Optimize the Preservation of Fresh Meat: Natural Food Additives to Extend Shelf-Life

Quality and safety are one of the main concerns of the European Union in food preservation. Using chemical additives extends the shelf-life of fresh foods but raises consumer's concerns about the potential long-term carcinogenic effects. Using natural substances derived from agro-industrial by-products, which have significant antimicrobial and antioxidant activities, could extend the shelf-life of fresh foods such as meat. Furthermore, they can provide nutritional improvements without modifying organoleptic properties. This study analyzes the antimicrobial activity of pomegranate peel extract (PPE) and the antioxidant activity of olive leaf extract (OLE), added at concentrations of 10 mg g-1 and 0.25 mg g-1, respectively, to minced poultry and rabbit meat. PPE exhibited in vitro antimicrobial activity against foodborne pathogens starting at 10 mg/well. PPE and OLE determined a reduction in colony count over a storage period of 6 days at 4 °C. Additionally, the combination of PPE and OLE showed antioxidant effects, preserving lipid oxidation and maintaining pH levels. The obtained results demonstrate that PPE and OLE can be recommended as food additives to preserve the quality and extend the shelf-life of meat products.

Preventing Microbial Growth in Game Meat by Applying Polyphenolic Extracts from Olive Mill Vegetation Water

We studied the efficacy of different formulations of polyphenol extracts (mainly containing hydroxytyrosol and tyrosol) from olive mill vegetation water on the microflora on the surfaces of game meat cuts with high or low initial bacterial loads. Meat with a high microbial load (>5 Log cfu/g; mean value = 6.83 ± 0.45 standard deviation) was immersed for 10 or 60 sec into 25% and 10% solutions of microencapsulated freeze-dried and non-encapsulated polyphenolic extracts. Aerobic colony, Enterobacteriaceae, Pseudomonas spp., and lactic acid bacteria counts were determined on treated samples compared to controls after 7 days of storage (in vacuum-packed conditions at +3 °C). Significant differences were registered only for aerobic colony count for a 10% liquid extract treatment (0.64 log reduction). In contrast, the dipping or immersion of game meat with low initial microbial loads (<5 Log cfu/g; mean value = 3.58 ± 0.72 standard deviation) in 10% solutions of the polyphenol extracts effectuated significant reductions in all bacteria counts (p < 0.002) at 7 and 14 days of storage for different extracts, independently from the application methods. The use of the extracts to inhibit bacterial growth in game meat should only be considered if a good hygienic baseline is guaranteed.

Antioxidant Activity of Beef, Pork and Chicken Burgers before and after Cooking and after In Vitro Intestinal Digestion

The aim of the present work was to evaluate and compare in vitro the antioxidant activity of raw, cooked and cooked-digested pork, beef and chicken burgers. The cooking process influenced the antioxidant capacity of the meat by decreasing the values of ABTS, FRAP and the content of free thiols. Conversely, a positive effect was observed after in vitro gastrointestinal digestion which increased the biological activity of the meat, characterised by greater antioxidant activity. The type of meat influenced the chemical composition and biological capacity of the burgers. In fact, both before and after the cooking process, beef burgers showed higher thiol content and, consequently, a higher oxidative stability of proteins than chicken and pork burgers. In vitro gastrointestinal digestion also improved the nutraceutical quality of beef burgers, which showed higher ABTS values and thiol content than pork burgers, which showed higher FRAP values. This work aims to support the potential of meat constituents as a natural antioxidant component that is essential to counteract the oxidative stress responsible for imbalances in the human organism and several cardiovascular diseases.

Effect of heat treatment on phenolic composition and radical scavenging activity of olive leaf extract at different pH conditions: a spectroscopic and kinetic study

BACKGROUND

The present study focused on the effect of isothermal treatment (5-90 °C) and pH (2.0-6.0) of aqueous olive leaf phenolic extract solutions on the kinetics of degradation of single and total phenolic compounds and radical scavenging activity, with the objective of predicting and optimizing the thermal treatments in foods enriched with olive leaf extracts.

RESULTS

The major compound, oleuropein, showed higher degradation at low pH 2.0 and temperature-dependent reaction rates, which fitted well a first-order kinetic model, with an estimated activation energy of 98.03 ± 0.08 kJ mol^-1 . Oleuropein hydrolysis resulted in a zero-order increase in hydroxytyrosol concentration at same pH (E_a  = 71.59 ± 1.5 kJ mol^-1 ), whereas a 100-fold slower degradation rate was observed at higher pH. Verbascoside was only degraded at pH 6.0, also following first-order kinetics. These changes in oleuropein and hydroxytyrosol concentrations led to significant changes in fluorescence maximum intensities centered around 315 and 360 nm and in the 425-500 nm spectral zone for samples at pH 6.0, which could be associated with verbacoside degradation. Conversely, analysis of total phenolic content and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity showed little changes, indicating a rather constant overall reducing capacity of the resulting pool of compounds after thermal treatments.

CONCLUSION

The present study can contribute to the knowledge related to oleuropein and phenolic fraction degradation as a result of matrix (pH) and processing. The kinetic parameters obtained could be applied for predicting and optimizing the thermal treatments in foods and drinks enriched with olive leaf extracts. © 2022 Society of Chemical Industry.

Protective effects of sugarcane phenolic extract against lipid oxidative damages in raw ground pork and beef during refrigerated storage conditions

The study evaluated the bioactive components and antioxidant properties of sugarcane phenolic extracts (SCPE) against lipid oxidation in raw ground pork and beef during refrigerated storage conditions. Results showed that SCPE has a high total phenolic content of 35.9 g GAE/100 g sample majority of which are vanillic (799.77 mg/100 g), sinapic (434.38 mg/100 g), and coumaric (342.37 mg/100 g) acids. These phenolic compounds exhibited strong radical scavenging activities against DPPH (191.00 mg TE/g) and ABTS (359.80 mg TE/g) radical, ferric reducing capacity (97.80 mg TE/g), and lipid peroxidation inhibition (120.20 mg TE/g) activities which are comparable to BHT. Supplementation of SCPE at 400 mg/kg fresh weight of ground pork and ground beef improved the antioxidant activities of meat samples, leading to the delay in TBARS formation, lower reduction in heme iron content, and minimal increase in metmyoglobin content during 14-day refrigerated storage as compared to BHT-treated and control. Moreover, the redness of meat was preserved in SCPE- and BHT-treated samples as measured by a* color value. Correlation heat maps showed that TBARS, metmyoglobin, and ΔE are positively correlated with each other, and at the same time showed negatively correlated with heme iron and a*. This study revealed that antioxidant extracts from sugarcane presented a positive effect on the oxidative stability of raw ground pork and beef during refrigerated storage.

Valorization of olive processing by-products via drying technologies: a case study on the recovery of bioactive phenolic compounds from olive leaves, pomace, and wastewater

Olive by-products are rich sources of phenolic compounds and their valorization is a favorable approach in line with sustainable development goals of the United Nations (UN) organization to promote well-being and production of healthier products; also, to deal with the environmental and economic subjects resulting in more profitability in the olive oil industry. The production of value-added ingredients from these by-products is not extensively exploited on the industrial scale. Drying is a critical pretreatment before extraction that can have a direct impact on the recovery and yield of the available bioactive compounds in olive by-products. In order to produce more stable and high quality phenolic products, encapsulation using spray and freeze drying is used. In this study, the effect of the drying process before and after extraction of bioactive compounds from olive by-products as a valuable source of phenolic compounds is reviewed. In addition, fortification using these ingredients and their incorporation in food formulations is also investigated.

Olive Leaf Extract (OLE) Addition as Tool to Reduce Nitrate and Nitrite in Ripened Sausages

Olive leaf extract (OLE) is known to be a source of phenolic compounds with antioxidant and antimicrobial activities. This study investigated the effects of the OLE addition to reduce nitrate/nitrite (NO) content on the physico-chemical features of ripened pork sausages. Seven formulations of pork sausages were set up: CTRL (0 mg/kg OLE; 300 mg/kg NO), Tr1 (200 mg/kg OLE; 150 mg/kg NO), Tr2 (400 mg/kg OLE; 150 mg/kg NO), Tr3 (800 mg/kg OLE; 150 mg/kg NO), Tr4 (200 mg/kg OLE; 0 mg/kg NO), Tr5 (400 mg/kg OLE; 0 mg/kg NO), and Tr6 (800 mg/kg OLE; 0 mg/kg NO). At the end of the ripening period, all the samples were within hygienic limits and the substitution of the additives with OLE allowed the reduction of NO residual contents. Both OLE and NO influenced the colour parameters. At the highest dose of OLE, both alone and in combination with reduced dose of NO, no significant differences in terms of moisture, pH, and aw were found compared to CTRL. In absence of NO, a significant reduction of weight loss was observed. Moreover, in the samples without NO a reduction of the hardness was detected. Finally, the oxidative stability test showed that the increase of the OLE amount prolonged the induction time.

Improved Oxidative Stability and Sensory Quality of Beef Hamburgers Enriched with a Phenolic Extract from Olive Vegetation Water

This study aims at evaluating the effect of a phenol-rich extract obtained from the concentration and purification of olive mill wastewaters (added at a ratio of 87.5 and 175 mg of phenols/kg meat) on the stability and sensory quality of beef hamburgers packed under modified atmosphere and stored under alternating exposure to fluorescent light at 4 ± 2 °C for 9 days. The hamburgers were sampled at different times (0, 6, and 9 days) and grilled at 200 °C. After 9 days, more than 56% of the added phenols in the raw burgers and more than 20% the grilled ones were retained. The results show that both concentrations of phenolic extract proved to effectively reduce primary and secondary lipid oxidation, as well as cholesterol oxidation products (COPs), during the shelf-life of raw hamburgers. Peroxide value, thiobarbituric acid reactive substances, and total COPs were up to 1.4-, 4.5-, and 8.8-fold lower in phenol-enriched raw hamburgers, respectively, than in the control samples; a similar trend was noted also in phenol-enriched cooked hamburgers (1.3-, 5.7-, and 4-fold lower). The sensory analysis also confirmed the effectiveness of the addition of phenolic extract, resulting in a positive effect on the red color intensity (raw product) and thus reducing browning during storage.

Determination of the Variability of Biophenols and Mineral Nutrients in Olive Leaves with Respect to Cultivar, Collection Period and Geographical Location for Their Targeted and Well-Timed Exploitation

The interactive effects of cultivar, collecting period, and geographical location on the content and composition of biophenols and macro and micronutrients in olive (Olea europaea L.) leaf were investigated. Leaves of six cultivars were collected at three periods in two locations in Croatia. The leaves of Istarska bjelica cultivar had the greatest biophenol (oleuropein) potential, especially those sampled in January and in March at the location of Pag. All the cultivars yielded leaves with the highest concentration of biophenols in March, which coincided with the pruning period. Except for high oleuropein concentration in Istarska bjelica, flavonoids were found to be most useful for differentiating olive leaves according to cultivar. Verbascoside turned out to be the most potent differentiator of collecting periods, while phosphorus and zinc turned out to be most useful for differentiating locations. Despite different agroecological conditions at the two locations, cultivar exhibited a significant effect on olive leaf nutrient composition, which was certainly causally related to that of the biophenols. The results obtained showed that it is possible to plan more well-timed and efficient exploitation of biophenols from olive leaf based on the knowledge about the interactive effects of the three studied factors.

The Effects of Pecan Shell, Roselle Flower and Red Pepper on the Quality of Beef Patties during Chilled Storage

The antioxidant and antimicrobial effects of pecan shell (PSW), combined with roselle flower (RS) and red pepper (CA) were analyzed in beef patties by several methods during chilled storage for 13 days. Additionally, the antioxidant and antimicrobial activities of PSW, RS and CA extracts were determined. The PSW extract exhibited a higher radical scavenging activity (by the DPPH method) and more total phenolic compounds than RS and CA. RS presented the best antimicrobial capacity. Nine formulations of beef patties were prepared, including a control (CM), a synthetic preservative (CAMPA N.3 (A)) and different combinations of PSW, RS and CA. The bacterial counts of the beef patties with RS (4-5 log colony-forming units (CFU)/g meat) were significantly lower than those of the control sample (CM) (6-7 CFU/g meat) at day 6. The thiobarbituric acid-reactive substance (TBARS) values at day 7 of all treatments were similar to the values of samples containing the synthetic antioxidant and significantly lower than the CM group. The order of stability assessed by the TBARS values were in agreement with the hexanal content. Thus, these results support the hypothesis that the combination of PWS, RS and CA could represent a good natural food preservative.

Phenolic Compounds Obtained from Olea europaea By-Products and their Use to Improve the Quality and Shelf Life of Meat and Meat Products-A Review

Consumers are interested in consuming clean label foods. Replacing synthetic additives with natural alternatives (especially sources rich in polyphenols) is a valid solution to produce and also preserve foods, especially meat and meat products. Olea europaea leaves and olive pomace and wastewater contain polyphenols that can be explored in this context. In this review, we summarize the main aspects related to the phenolic composition, extraction conditions, antimicrobial potential, and antioxidant activity (in vitro and in vivo) of Olea europaea leaves, olive pomace and wastewater as well as their applications in the production of meat and meat products. This review found evidence that extracts and isolated polyphenols from the Olea europaea tree and olive processing by-products can be explored as natural antioxidant and antimicrobial additives to improve the preservation of meat and meat products. The polyphenols found in these residues (especially oleuropein, hydroxytyrosol and tyrosol) increased the redox state in the main meat-producing animals and, consequently, the oxidative stability of fresh meat obtained from these animals. Moreover, the extracts and isolated polyphenols also improved the shelf life of fresh meat and meat products (as additive and as active component in film) by delaying the growth of microorganisms and the progression of oxidative reactions during storage. The accumulated evidence supports further investigation as a natural additive to improve the preservation of reformulated muscle products and in the production of edible and sustainable films and coatings for fresh meat and meat products.

Effects of Olive Leaf Extracts as Natural Preservative on Retailed Poultry Meat Quality

Poultry meat is commonly marketed at refrigerated temperatures (2-5 °C). The major concern for retailers and consumers is the quality and safety of refrigerated poultry meat. During the chilling period, poultry meat undergoes too many undesirable changes due to microbial growth that leads to spoilage and economic loss. Therefore, this study was conducted to assess the effects of olive leaf extracts (OLE) used at three concentrations (0.25, 0.5, and 1%) on the sensory attributes, as well as the chemical and microbiological quality of raw poultry meat stored at 4 ± 1 °C for 15 days. The results revealed that the OLE addition reduced microbial growth successfully, and maintained the chemical quality and sensory attributes of poultry meat. Moreover, OLE extended the shelf-life of the poultry meat that held under proper refrigeration conditions up to 15 days compared to the control group, that was completely spoiled by the sixth day of storage. This study concludes that OLE could be used both as a natural antioxidant and an antimicrobial preservative for chilled poultry meat held at refrigerated temperature.

Physical and Sensory Properties of Mayonnaise Enriched with Encapsulated Olive Leaf Phenolic Extracts

This work aimed to study the physical, structural, and sensory properties of a traditional full-fat mayonnaise (≈ 80% oil) enriched with an olive leaf phenolic extract, added as either free extract or encapsulated in alginate/pectin microparticles. Physical characterization of the mayonnaise samples was investigated by particle size, viscosity, lubricant properties, and color; a sensory profile was also developed by a quantitative descriptive analysis. The addition of the extract improved the dispersion degree of samples, especially when the olive leaf extract-loaded alginate/pectin microparticles were used. The encapsulated extract affected, in turn, the viscosity and lubricant properties. In particular, both of the enriched samples showed a lower spreadability and a higher salty and bitter perception, leading to a reduced overall acceptability. The results of this study could contribute to understanding the effects of the enrichment of emulsified food systems with olive by-product phenolic extracts, both as free and encapsulated forms, in order to enhance real applications of research outcomes for the design and development of healthy and functional formulated foods.

Composition and Antibacterial Activity of Aronia melanocarpa (Michx.) Elliot, Cornus mas L. and Chaenomeles superba Lindl. Leaf Extracts

The purpose of this study was to investigate the composition of leaf extracts from Aronia melanocarpa, Chaenomeles superba, and Cornus mas, and their antimicrobial activity against typical spoilage-causing and pathogenic bacteria found in meat and meat products. The highest total phenolic content (TPC) was detected in C. superba extract, followed by C. mas and A. melanocarpa extracts. The antioxidant capacity of the extracts was measured by DPPH and ABTS assays. The lowest IC₅₀ values were found for C. superba extract, followed by C. mas and A. melanocarpa extracts. LC-MS and HPLC analysis revealed that A. melanocarpa and C. superba extracts contained hydroxycinnamic acid derivatives and flavonoids (mainly flavonols). Hydroxycinnamic acid derivatives were detected in the C. mas extract, as well as flavonols, ellagitannins, and iridoids. The antibacterial activity of the plant extracts was tested against Gram-negative bacteria (Moraxella osloensis, Pseudomonas fragi, Acinetobacter baumanii, Escherichia coli, Enterobacter aerogenes, Salmonella enterica) and Gram-positive bacteria (Enterococcus faecium, Staphylococcus aureus, Brochothrix thermosphacta, Lactobacillus sakei, Listeria monocytogenes) using the microculture method. The extracts acted as bacteriostatic agents, decreasing the growth rate (µ_max) and extending the lag phase (t_lag). C. mas showed most potent antibacterial activity, as confirmed by principal component analysis (PCA).

Effect of Feed Supplemented with Selenium-Enriched Olive Leaves on Plasma Oxidative Status, Mineral Profile, and Leukocyte DNA Damage in Growing Rabbits

Simple Summary

Olive trees (Olea europaea L., Oleaceae) are among the most extensively cultivated crops in the Mediterranean countries (98% of the world’s olive production) and are used for oil extraction or table olives, whereas the residues from pruning (olive leaves and wood) and extraction process (olive pomace) are considered waste or by-products. Furthermore, many agronomic practices, such as foliar spray administration of selenium used to reduce the water stress damage of olive trees, could further improve the nutritional value of these “wastes”. The use of by-products as part of the rabbit diet can be a very effective example of recovery of healthy molecules while at the same time a way of developing a more sustainable production system. Accordingly, the idea of the present research is to administer the by-product “olive leaves” to growing rabbits to improve their health status and partially solve the problem of waste disposal of olive trees.

Abstract

This study investigated the effect of a dietary combination of selenium and olive leaves on rabbit health status in order to evaluate the potential use of these combinations as functional ingredients in feed and food. Sixty weaning rabbits were fed with three diets: control feed (C), control feed + 10% normal olive leaves (OL), or olive leaves enriched in Se (2.17 mg Se/kg d.m.; SeOL). The plasma mineral profile, antioxidant status, and leukocyte DNA damage were determined. Inorganic Se was the most abundant form in the OL diet, while the organic one was higher in SeOL than C and OL. A similar trend was found in the plasma. Protein oxidation showed higher values in both supplemented groups; in addition, dietary Se led to a significant improvement (+40%) in ferric reducing ability of plasma (FRAP). A marked reduction in DNA damage (9-fold) was observed in the SeOL group compared to C. The combination of selenium and olive leaves in the diet of growing rabbits increased plasma SeMet and FRAP and reduced leukocyte DNA damage.

Plant extracts rich in polyphenols: antibacterial agents and natural preservatives for meat and meat products

Plant extracts contain large amounts of bioactive compounds, mainly polyphenols. Polyphenols inhibit the growth of microorganisms, especially bacteria. Their mechanism of action is still not fully understood but may be related to their chemical structure. They can cause morphological changes in microorganisms, damage bacterial cell walls and influence biofilm formation. Polyphenols also influence protein biosynthesis, change metabolic processes in bacteria cells and inhibit ATP and DNA synthesis (suppressing DNA gyrase). Due to the antioxidant and antibacterial activity of phenolic compounds, plant extracts offer an alternative to chemical preservatives used in the meat industry, especially nitrates (III). They can inhibit the growth of spoilage and pathogenic microflora, suppress oxidation of meat ingredients (lipids and proteins) and prevent discoloration. In this paper, we describe the factors that influence the content of polyphenols in plants and plant extracts. We present the antimicrobial activities of plant extracts and their mechanisms of action, and discuss the effects of plant extracts on the shelf-life of meat and meat products.

The Effect of Natural Antioxidants on Quality and Shelf Life of Beef and Beef Products

Oxidation processes are the major cause of deterioration of meat quality and shelf life of meat products, leading to negative changes in nutritive value and in sensory and physicochemical properties of meat. Until now, the synthetic antioxidants like butylated hydroxyl anisole have been commonly used to prevent oxidation, which however may cause potential human health risks and increase toxicity of the product. However, natural antioxidants can be the alternative solution for this problem since plants and plant materials are rich in bioactive compounds (as natural antioxidants) with potential health beneficial effects. Moreover, the interest of consumers in using natural products is still increasing. There is an expectation of replacing synthetic antioxidants and preservatives by natural ones. Therefore, the aim of the present review is to provide information on the effect of natural antioxidants from vegetables and fruits like olives, pomegranate or grapes, and herbs and spices like rosemary, oregano, sage, black cumin or turmeric, rich in bioactive compounds on quality and shelf life of beef and beef products.

Characterization of bioactive compounds in commercial olive leaf extracts, and olive leaves and their infusions

A large spectrum of beneficial health properties has been attributed to olive leaves. This study was undertaken to characterize the bioactive compounds of commercial olive leaf extracts and olive leaves and their infusions. High variability of bioactive compounds was found among commercial samples. Polyphenol was detected in a range of 44-108 g kg^-1 and 7.5-250 g kg^-1 for olive leaves and olive leaf extracts, respectively. The main phenol was oleuropein, representing 74-94% of total phenols. However, only 17-26% of polyphenols were diffused to the aqueous phases when olive leaf infusions were prepared. Triterpenic acids were found in a range of 26-37 g kg^-1 in olive leaves, but not detected in the infusions. Hence, the absence of the latter substances and the low oleuropein diffusion in olive leaf infusions make new studies necessary to maximize the presence of these bioactive compounds in the final product.

Effect of Linseed Supplementation on Total Longissimus Muscle Lipid Composition and Shelf-Life of Beef From Young Maremmana Bulls

Twenty young Maremmana bulls were randomly allotted to two dietary groups during a finishing period (~90 days): C diet (without lipid supplementation), and L diet (with linseed supplementation, 20% concentrate feed). The aim was to investigate the effects of dietary linseed supplementation on the intramuscular fat composition, and the shelf-life of minced beef. The L diet did not alter the dressing rate and daily weight gain, whereas the C18:3n-3 content in the intramuscular fat significantly increased (from 0.85 to 1.78 g/100 g of total fatty acid, +109%), leading to a reduction in a n-6/n-3 ratio below four and an increase in the overall proportion of long chain n-3 fatty acids in beef lipids. These effects were principally related to differences in the distribution of fatty acids between the neutral and polar lipids. The results demonstrated that linseed supplementation modified the lipid composition of beef, without negatively impacting overall productivity, in the period from weaning the bull until its slaughter. However, the total amount of n-3 fatty acids in the beef of young bulls on the L diet, was not sufficient for the aliquot of humans' n-3 fatty acid requirements. This was mainly related to the low levels of fat in the beef. Comparing beef samples from animals on the L diet, with samples from animals on the C diet, the higher levels of n-3 polyunsaturated fatty acids led to a significant reduction of shelf-life starting after 2 days of storage at 4°C, because of fatty acid and cholesterol oxidation. The L diet group samples showed a higher level of TBARS (+80%) and COPs (+73%), two important parameters to estimate the oxidation level of beef. This suggests that enriching beef with n-3 fatty acids should be coupled with packaging techniques that consider the higher susceptibility to lipid oxidation. In conclusion, dietary linseed supplementation led to a higher proportion of n-3 fatty acids in beef lipids, however, the natural content of antioxidant substances was not able to protect intramuscular fat from oxidation during storage at 4°C.

Olive leaf extracts for shelf life extension of salmon burgers

In this work, the effect of the addition of olive leaf extracts on the quality of vacuum-packed salmon burgers stored at 4 ℃ during 16 days has been studied. Olive leaf extract and its hydrolysate were initially characterized and then incorporated to salmon burgers. A shelf life study was conducted in three different batches (control, olive leaf extract, and hydrolyzed olive leaf extract burgers). Among the chemical indices determined, total volatile base nitrogen values were lower in hydrolyzed olive leaf extract and olive leaf extract burgers than in control samples. Lipid oxidation was lower in salmon burger with olive leaf extract. Salmon mince treated with hydrolyzed olive leaf extract showed lower microbial counts during the whole study, which extended the shelf life of the fish product. Therefore, the potential of olive leaf extracts to preserve salmon burgers during cold storage has been demonstrated.