Combined effects of ε-polylysine and ε-polylysine nanoparticles with plant extracts on the shelf life and quality characteristics of nitrite-free frankfurter-type sausages

Polycaprolactone (PCL)-based films integrated with hairy cellulose nanocrystals and silver nanoparticles for active Tilapia packaging applications

The migration of metal ions to the food matrix has been always a challenge in the production of active food packaging films. In this study, it was tried to evaluate the idea of using hairy cellulose nanocrystals (HCNs) in controlling the migration of Silver Nanoparticles (AgNPs) from polycaprolactone (PCL)-based films to the Tilapia fish. HCNs and the final films (integrated with various amounts of HCNs and AgNPs) were evaluated physicochemically and mechanically. Tilapia fish were packed using the films and after specific periods, the fish samples were assessed microbiologically and physiochemically. According to the results, incorporating NPs into PCL films enhanced tensile strength, elasticity, and toughness making the films more resistant to breakage and deformation under stress. The introduction of HCNs reduced the surface roughness level, decreasing AgNPs migration, but also accelerated the degradation rate. Films with [1% AgNPs +2% HCNs] and [1% AgNPs] had the lowest and highest water vapor transmission rate. The use of AgNPs (1%) + HCNs (2%) incorporated into PCL films resulted in a lower pH value, TVB-N, TBARs, and PV. It also decreased microbial activities in samples in comparison to the control. Therefore, the idea of using HCNs along with antibacterial metal-based nanoparticles can control the rate of ion migration.

Effect of cinnamaldehyde-nanoemulsion and nanostructured lipid carriers on physicochemical attributes of reduced-nitrite sausages

This study aimed to produce cinnamaldehyde (CA)-loaded nanostructured lipid carriers (NLC) and nanoemulsion (NE) to replace nitrite in sausage. The NLC and NE droplet sizes were 132 and 116 nm with encapsulation efficiency of 98 and 96 %, respectively. In in vitro antimicrobial assessment, the free CA and NE showed higher microbial activity against S. aureus and E. coli than NLC. Meanwhile, NE showed a faster release profile for CA than NLC. Among the samples, NE and NE + nitrite indicated the lowest peroxide value (3.7 ± 0.1), TVBN amount (8.6 ± 0.2), acidity (0.3 ± 0.02), microbial quality (against E. coli, C. perfringens, lactic acid bacteria, psychrophilic bacteria, total mold and yeast, and total viable counts), and sensory attribute, while the NE + nitrite sample exhibited better color properties and higher oxymyoglobin content (5-10 % higher). Therefore, NE + nitrite can be the best choice due to supporting the different quality parameters of sausage.

Chitosan Coating with Rosemary Extract Increases Shelf Life and Reduces Water Losses from Beef

This study aimed to evaluate the influence of films based on chitosan and rosemary extract on the physicochemical, microbiological, and oxidative characteristics of beef. Refrigerated steaks of Longissimus dorsi were distributed in a factorial arrangement (4 × 4) into four treatments consisting of four edible films (control; chitosan; chitosan + 4% rosemary extract; and chitosan + 8% rosemary extract) and four days of aging (0, 2, 4, and 8 days). Incorporating 4% or 8% rosemary extract into the chitosan film improved the characteristics of the films in terms of moisture absorption and elasticity. The edible coatings with chitosan and rosemary extract and the different days of aging increased the tenderness and decreased the lipid oxidation of beef. In addition, the chitosan films containing rosemary extract increased the water-holding capacity and decreased the cooking losses of beef. The films containing 4% and 8% rosemary extract decreased the development of mesophilic and psychrotrophic bacteria and Staphylococcus ssp. in beef. We recommend incorporating 4% rosemary extract into chitosan-based coatings to preserve the quality of refrigerated beef.

Research progress on natural preservatives of meat and meat products: classifications, mechanisms and applications

Meat and meat products are highly susceptible to contamination by microorganisms and foodborne pathogens, which cause serious economic losses and health hazards. The large consumption and waste of meat and meat products means that there is a need for safe and effective preservation methods. Furthermore, toxicological aspects of chemical preservation techniques related to major health problems have sparked controversies and have prompted consumers and producers to turn to natural preservatives. Consequently, natural preservatives are being increasingly used to ensure the safety and quality of meat products as a result of customer preferences and biological efficacy. However, information on the current status of these preservatives is scattered and a comprehensive review is lacking. Here, we review current knowledge on the classification, mechanisms of natural preservatives and their applications in the preservation of meat and meat products, and also discuss the potential of natural preservatives to improve the safety of meat and meat products. The current status and the current research gaps in the extraction, application and controlled-release of natural antibacterial agents for meat preservation are also discussed in detail. This review may be useful to the development of efficient food preservation techniques in the meat industry. © 2024 Society of Chemical Industry.

A Comprehensive Review of Cured Meat Products in the Irish Market: Opportunities for Reformulation and Processing

Cured meat products constitute one of the meat categories commonly consumed in Ireland and has been part of the Irish cuisine and diet for many years. Ham, gammon, and bacon are some of the products that involve curing as part of the traditional processing methods. Common among these products are high levels of salt and the addition of nitrites. These products undergo processing treatments to create variety, preserve shelf-life, and develop their unique quality and safety characteristics. However, consumers are becoming more conscious of the level of processing involved in these products, and the effects of some components and ingredients might be perceived as unhealthy. Meat product developers have been exploring ways to reduce the amount of ingredients such as salt, saturated fat, and chemical preservatives (e.g., nitrites), which are linked to health concerns. This is a challenging task as these ingredients play an important techno-functional role in the products' quality, safety, and identity. While innovative processing techniques are being introduced and progress has been made in reformulation and packaging technologies, much is still unknown, especially regarding the applicability of many of the proposed interventions to a wide range of meat products and their sustainability at the industrial scale.

A comparative study between the performance of thymol-nanoemulsion and thymol-loaded nanostructured lipid carriers on the textural, microbial, and sensory characteristics of sausage

The objective of this research was to compare the function of thymol-loaded nanostructured lipid carriers (NLC) and a thymol-nanoemulsion (NE) with nitrite (120 mg/kg) on quality parameters of sausage. The droplet size of the NLC and NE was 140 and 86.39 nm with encapsulation efficiency of 97 and 94%, respectively. The results on sausage showed that all samples containing NLC and NE exhibited the lowest increase in peroxide value, total volatile base-nitrogen, and TBA with the highest inhibitory effect on the growth of E. coli, C. perfringens, lactic acid bacteria, psychrophilic bacteria, mold and yeast, and total viable counts as well as good texture and sensory attributes with the best results in the NLC + nitrite and NE + nitrite samples. The L* and a* values were relatively higher in the samples treated with nitrite, NLC + nitrite, and NE + nitrite after 4-week storage. This increase in redness was associated with the maintenance of oxymyoglobin levels and a decrease in metmyoglobin production. The results of this study indicated that the combined use of NLC/NE (particularly NE) with 60 mg/kg nitrite significantly improved the oxidative and color stability, and delayed the spoilage and off-flavor in sausage.

Development and characterization of smart double-layer nanofiber mats based on potato starch-turnip peel anthocyanins and guar gum-cinnamaldehyde

This experiment was conducted with the objectives of developing bilayer nanofiber mats based on potato starch-turnip peel extract (PS-TPE) and guar gum-cinnamaldehyde (GG-CA) for freshness monitoring and enhancing the quality of lamb meat during cooled storage conditions. Encapsulating CA/TPE into the nanofibers resulted in reduced tensile strength, water vapor permeability, moisture content, and water solubility. Colorimetric nanofibers, including PS-GG-TPE 6%, PS-GG-TPE 6%-CA 0.5%, and PS-GG-TPE 6%-CA 1%, presented red color at pH 1-4, purplish red at pH 5-7, green at pH 8-10, and brown at pH 11-12. The color of PS-GG-TPE 6% nanofiber mats changed from white to purplish red, signaling that the lamb meats had turned from fresh to spoiled. PS-GG-CA 1%, PS-GG-TPE 6%-CA 0.5%, and PS-GG-TPE 6%-CA 1% nanofibers have the potential to be utilized to control the growth of spoilage-related microorganisms for extending the shelf-life of fresh lamb meat under cooled storage conditions up to 13 days.

Investigating the effects of chitosan/ tragacanth gum/ polyvinyl alcohol composite coating incorporated with cinnamon essential oil nanoemulsion on safety and quality features of chicken breast fillets during storage in the refrigerator

The present study investigated the effects of composite coatings made of chitosan (CS), tragacanth gum (TG), and polyvinyl alcohol (PVA) containing cinnamon essential oil (CEO) on the shelf-life of refrigerated chicken breast fillets. The samples were treated with different coating dispersions, and coded as: T1 (distilled water as control), T2 (blank composite coating), and T3 (composite coating containing CEO). Results showed that incorporating CEO into CS/TG/PVA coatings could significantly increase the quality of chicken fillets. The obtained results showed that after 21 days, the total microbial population of lactic acid bacteria (LAB), psychrotrophic and mesophilic bacteria in T3 samples was less than T1 and T2 samples. In addition, the highest antioxidant activity (48.04 %) and total phenolic content (TPC) values (2.458 mg gallic acid /g), the best sensory characteristics and the lowest pH (5.73), total volatile basic nitrogen (TVB-N) (21.89 mg N/100 g), thiobarbituric acid reactive substances (TBARS) (1.678 mg malondialdehyde equivalent/kg) and percentage of cooking loss (30 %) were related to T3. Results disclosed that this composite coating is a promising technology to improve the shelf life of chicken fillets during storage.

Development of biomaterials based on chitosan-gelatin nanofibers encapsulated with Ziziphora clinopodioides essential oil and Heracleum persicum extract for extending the shelf-life of vacuum-cooked beef sausages

The aims of the current study were to encapsulate Ziziphora clinopodioides essential oil (ZEO, 0%, 0.15%, and 0.25%) and Heracleum persicum extract (HPE, 0%, 0.25%, and 0.5%) into the chitosan-gelatin (CH-GE) nanofibers through the electrospinning process to improve the shelf-life of vacuum-cooked beef sausages through 70 days of refrigerated storage. Scanning electron microscopy indicated that all nanofibers appeared thin, well-defined, smooth, and possessed uniform thread-like fibers without any beads or nodule formations. The Fourier transform infrared spectroscopy study confirmed the molecular interaction between encapsulated compounds and CH-GE nanofibers. The X-ray diffraction analysis of nanofibers showed an increase in crystallinity after incorporating ZEO and HPE into the polymer. Treated sausages with CH-GE-ZEO 0.25%-HPE 0.25% and CH-GE-ZEO 0.25%-HPE 0.5% showed significantly lower microbial population and lipid oxidation than the control group during the experiment period (P < 0.05). Sausages formulated with designated CH-GE nanofibers had better microbial, chemical, and sensory properties compared to sausages treated with pure ZEO/HPE during refrigerated storage. The findings also showed that treated sausages with CH-GE-ZEO 0.25%-HPE 0.5% had the highest color, odor, texture, and overall acceptability after 70 days of refrigerated storage conditions. Therefore, this treatment could be applicable for the prolonged storage conditions during cooked beef sausage production.

Impact of sodium alginate-based film loaded with resveratrol and thymol on the shelf life of cooked sausage and the inoculated Listeria monocytogenes

In present study, sodium alginate biodegradable films containing different concentrations of resveratrol (RES: 0.002% and 0.004%) or thymol (THY: 0.5% and 1%) and their combinations were prepared, and evaluated for their effects on spoilage-related microbial profile, lipid oxidation, sensory properties, and protective effects against Listeria monocytogenes in beef mortadella sausage during 40 days storage at 4°C. The release rate of phenolic compounds was determined by the Folin-Ciocalteu test. To assess the shelf life of the product, changes in total viable count (TVC), lactic acid bacteria count (LAB), psychrotrophic bacteria count (PTC), pH levels, thiobarbituric acid reactive substances (TBARS) levels, and sensory characteristics (taste, color, odor, and overall acceptability) were evaluated. For the sensory evaluation, a panel of 70 semi-trained judges was selected according to their initial performance. Samples wrapped with sodium alginate films containing 1% THY (alone or combined with different concentrations of RES) exhibited lower bacterial counts compared to other experimental groups at the end of the storage period (6.01-6.35 vs. 6.71-8.17 log10 CFU/g for TVC, 5.37-5.83 vs. 6.07-7.11 log10 CFU/g for LAB, 5.08-5.18 vs. 5.40-7.23 log10 CFU/g for PTC, and 6.53-6.92 vs. 7.23-9.01 log10 CFU/g for inoculated L. monocytogenes). Sodium alginate films containing the combination of 0.004% RES and different concentrations of THY showed higher antioxidant effects than other experimental groups (TBARS values of 1.68-1.99 vs. 2.23-3.80 mg MDA/kg sample). The sodium alginate film containing 0.004% RES + 1% THY exhibited the highest antimicrobial and antioxidant activities and highest sensory scores among all treatments. These findings highlight the potential application of the sodium alginate film containing a combination of RES and THY as an active packaging material with natural preservatives in the meat products industry. This application can effectively extend the shelf life and enhance the microbial safety of clean-label cooked sausages during refrigerated storage.

The effects of double gelatin containing chitosan nanoparticles-calcium alginate coatings on the stability of chicken breast meat

The effects of gelatin coatings (2% and 4%) containing chitosan nanoparticles (ChNPs; 1% and 2%), in combination with calcium-alginate coatings (CA; 2%), on quality attributes and shelf life of chicken breast meat were evaluated at 4°C for 12 days. The results indicated that double-active gelatin-calcium alginate coatings had significant (p < .05) effects on moisture and protein content. Incorporation of ChNPs into double gelatin-CA coatings led to significant reduction (p < .05) in TBARS, pH, and TVB-N values at the end of storage. The counts of total viable count (TVC), coliforms, yeasts, and molds were significantly (p < .05) lower in all coated samples, particularly in treated samples by 4% gelatin containing 2% ChNPs + 2% CA coatings (6.85, 6.78, and 5.91 log CFU/g, respectively, compared with 8.35, 8.76, and 7.71 log CFU/g in control) at the end of keeping time. The results of sensory attributes showed that the coated samples had higher overall acceptability scores compared with the untreated samples. A synergistic relationship between the concentrations of gelatin and ChNPs was observed in maintaining the quality characteristics of meat samples during storage. Therefore, this study aims to evaluate the performance of double gelatin coating containing ChNPs in combination with CA coating in the storage quality improvement of chicken breast meat stored for 12 days at 4 °C to develop novel and practical coatings for meat and meat products.

Nisin and Organic Acid Salts Improved the Microbial Quality, Extended the Shelf Life, and Maintained the Sensory Attributes of Semidry Beef Luncheon Marketed at Adverse (35-40 °C) Ambient Summer Temperatures

Semidry beef luncheon may undergo deteriorative changes during storage at ambient temperatures in tropical and subtropical regions including Egypt. This study was conducted in a meat plant in Egypt with the aim of overcoming the economic losses from the returns of spoiled unsold beef luncheon displayed in grocery stores at adverse summer temperatures of 37 °C or more. Ten approaches were applied using different preservatives, comprising sodium nitrite, nisin, potassium sorbate, and organic acid salts (a combination of sodium lactate, sodium acetate, and sodium diacetate). In addition, the product was cooked at different temperatures and was stored for 21 days at 37 °C, during which time the shelf life, microbial quality, pH, and sensory attributes were investigated. By Day 21 of storage, the luncheon contained 50 mg/kg sodium nitrite, 25 mg/kg nisin, and 1000 mg/kg organic acid salts and, when cooked at a final core temperature of 92 °C, exhibited reductions in aerobic plate count, anaerobic plate count, lactic acid bacterial count, and mold and yeast counts by 4.32, 3.54, 3.47, and 1.89 log10 CFU/g, respectively, when compared with the control. The sensory attributes and pH were also maintained in the final products of such treatment, with no product return and the avoidance of economic loss. This study presents a novel approach for solving the major problem of the deteriorative changes that occur in semidry luncheon sausage and similar meat products which require rejection with a huge economic loss, especially in tropical and semitropical areas of the world that have similar problems of high climatic temperatures and a low availability of energy or technological resources.

Quantification of Bioactive Metabolites Derived from Cell-Free Supernatant of Pediococcus acidilactici and Screening their Protective Properties in Frankfurters

The specific aims of the current study were to determine and quantify the bioactive compounds derived from the cell-free supernatant (CFS) of Pediococcus acidilactici and screen their protective effect in frankfurters by applying an edible coating. This was achieved by immersing the peeled frankfurters in the CFS (CFS: 50% and 100%) alone or in combination with chitosan (CH: 0.5% and 1%) solutions for 3 min. Untreated frankfurter samples (control) exceeded the maximum acceptable total viable count limit (7.0 log10) on the 14th day, whereas samples treated with 100% CFS + 1% chitosan reached the limit on day 28 during refrigerated storage (P < 0.05). This treatment provided a 14-day extension to the shelf life of frankfurters without causing any significant changes in color and sensory attributes (P > 0.05). Additionally, this treatment inhibited oxidation in the frankfurters, leading to no significant changes in TBA and TVB-N within this group during storage (P > 0.05). This protective effect was mainly attributed to the wide variety of bioactive compounds identified in the CFS, including a total of 5 organic acids, 20 free amino acids, 11 free fatty acids, 77 volatiles, and 10 polyphenols. Due to these bioactive compounds, CFS exhibited a strong radical scavenging capacity (DPPH: 435.08 TEAC/L, ABTS: 75.01 ± 0.14 mg TEAC/L; FRAP: 1.30 ± 0.03 mM FE/L) and antimicrobial activity against microorganisms primarily responsible for the spoilage of frankfurters. In conclusion, the results indicate that the CFS contains high levels of bioactive metabolites, and an edible chitosan coating impregnated with CFS can be utilized to extend the shelf life of frankfurters through its antimicrobial effects and oxidation stabilization.

Novel Approaches to Improve Meat Products' Healthy Characteristics: A Review on Lipids, Salts, and Nitrites

Meat products are a staple of many diets around the world, but they have been subject to criticism due to their potential negative impact on human health. In recent years, there has been a growing interest in developing novel approaches to improve the healthy characteristics of meat products, with a particular focus on reducing the levels of harmful salts, lipids, and nitrites. This review aims to provide an overview of the latest research on the various methods being developed to address these issues, including the use of alternative salts, lipid-reducing techniques, and natural nitrite alternatives. By exploring these innovative approaches, we can gain a better understanding of the potential for improving the nutritional value of meat products, while also meeting the demands of consumers who are increasingly concerned about their health and well-being.

The Combination of Corona Discharge Plasma and ε-Polylysine for the Inactivation of Serratia liquefaciens

The purpose of the study was to investigate the mechanism of inactivation of Serratia liquefaciens by different treatments, namely corona discharge plasma (CDP), ε-polylysine (ε-PL), and corona discharge plasma combined with ε-polylysine (CDP plus ε-PL). The results showed that the combined treatment of CDP and ε-PL exhibited significant antibacterial effects. The total number of colonies of S. liquefaciens dropped by 0.49 log CFU/mL following 4 min of CDP treatment, 4MIC ε-PL treatment for 6 h alone decreased the amounts of colonies by 2.11 log CFU/mL, and 6 h of treatment with 4MIC ε-PL after the bacterium was treated with CDP could decrease the number of colonies by 6.77 log CFU/mL. Scanning electron microscopy images showed that the combined treatment of CDP and ε-PL caused the most serious damage to the cell morphology. Electrical conductivity, nucleic acid, and PI staining indicated that the combined treatment dramatically enhanced the permeability of the cell membrane. In addition, the combined treatment led to a significant decrease in SOD and POD enzyme activities in S. liquefaciens, which prevented energy metabolism. Finally, the determination of free and intracellular ε-PL concentrations confirmed that the treatment of CDP could cause the bacteria to bind more ε-PL and exert more significant bacterial inhibition. Therefore, CDP and ε-PL had a synergistic effect in the inhibition of S. liquefaciens.

Effects of nitrite-rich and pigment-rich substitutes for sodium nitrite on the quality characteristics of emulsion-type pork sausages during cold storage

This study was conducted to evaluate the effects of nitrite-rich (celery powder; CP) and pigment-rich (purple sweet potato powder, PSP; red beet powder, RB) substitutes for synthetic sodium nitrite (CON) on the quality characteristics of emulsion-type pork sausages during four weeks of cold storage. Natural substitutes decreased the pH, lightness, and textural properties of pork sausages during storage (P < 0.05). Pigment-rich substitutes showed a decreased antioxidant effect after two weeks of storage when compared to the nitrite-rich groups (CON and CP; P < 0.05). Pigment-rich substitutes also accelerated the discoloration of pork sausages by increasing yellowness (RB and PSP) and decreasing redness (PSP) during storage (P < 0.05). However, these two pigment-rich substitutes showed different trends in redness (higher in PSP and lower in RB) and yellowness (higher in RB and lower in PSP) when compared to the nitrite-rich groups (CON and CP). Different types (nitrite-rich and pigment-rich) of natural substitutes for sodium nitrite had different effects on the quality characteristics of emulsion-type pork sausages throughout the four weeks of storage evaluated in this study.

Study on film forming characteristic of ε-polylysine grafted chitosan through TEMPO oxidation system and its preservation effects for pork fillet

The present study synthesized a new type of ε-polylysine (PL) modified chitosan film (TO-CH-PL) through TEMPO (2,2,6,6-Tetramethylpiperidine) oxidation system. Firstly, the physicochemical properties of the TO-CH-PL were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive spectrometer analysis. Results proved that PL was successfully grafted onto chitosan molecules. Based on the water vapor, oxygen permeability, and mechanical analysis, the TO-CH-PL film demonstrated higher physical properties than chitosan and PE films. Secondly, the TO-CH-PL film's preservation effect on pork fillets was evaluated. Due to the significant retardation of growth of the aerobic plate count (APC), total volatile basic nitrogen (TVBN), and thiobarbituric acid reactive substances (TBARS), as well as the changes of pH and color in packaged pork, TO-CH-PL film exhibited better preservation effects for the pork samples. According to the criteria of TVBN values (<15 mg/100 g), compared with CH and PE films, TO-CH-PL film can prolong the shelf life of pork for 2 to 3 days. Therefore, PL-modified chitosan films could be introduced as an alternative method to maintain the quality indices and extend the shelf life of pork during refrigerated storage.

Application of oleaster leaves (Elaeagnus angustifolia L.) essential oil and natural nanoparticle preservatives in frankfurter-type sausages: An assessment of quality attributes and stability during refrigerated storage

The effects of oleaster leave essential oil (OLEOs: 1000 and 2000 ppm) in combination with nisin nanoparticles (200 ppm) and ε-polylysine nanoparticles (2000 ppm) on the physicochemical, microbiological and sensory properties of the emulsion-type sausages without added chemical nitrite/nitrate salts were evaluated during 45 days of storage. Nanoparticle attributes were assessed, including encapsulation efficiency (EE%), zeta potential, nanoparticles size, FTIR analysis, and thermal stability (DSC). Overall, ε-PL nanoparticles (ε-PL-NPs) were thermally more stable and showed higher EE% (91.52%) and zeta potential (37.80%) as compared to nisin nanoparticles (82.85%) and (33.60%), respectively. The use of combined ε-PL-NPs (2000 ppm) + Ni-NPs (200 ppm) with oleaster leaves essential oil (2000 ppm) resulted in a higher pH value (5.88), total phenolic content (10.45 mg/100 g) and lower TBARS (2.11 mg/kg), and also decreased total viable bacteria (1.28 Log CFU/g), Clostridium perfringens (1.43 Log CFU/g), E. coli (0.24 Log CFU/g), Staphylococcus aureus (0.63 Log CFU/g), and molds and yeasts (0.86 Log CFU/g) count in samples at day 45 in comparison to the control (120 ppm nitrite). The consumers approved sensory traits in nitrite-free formulated sausages containing ε-PL-NPs and Ni-NPs combined with OLEOs.

Nanoemulsion-based approach to preserve muscle food: A review with current knowledge

Muscle foods are regarded as nutritionally dense foods while they are prone to spoilage by action of microorganism and oxidation. Recently, the consumer's preference is mostly toward minimally processed foods as well as preserved with natural preservatives. However, natural extract directly to the food matrix has several drawbacks. Hence development and applications of nanoemulsion has gained importance for the preservation of muscle foods to meet consumer requirements with enhanced food safety. Nanoemulsion utilizes natural extracts at much lower concentration with higher preservative abilities over original components. Nanoemulsions offer protection to the active component from degradation and ensure longer bioavailability. Novel techniques used for formulation of nanoemulsion provide stability to the emulsion with desirable qualities to improve their impacts. The application of nanoemulsion is known to enhance the preservative action of nanoemulsions by improving the microbial safety and oxidative stability in nanoform. This review provides recent updates on different methods used for formulation of nanoemulsions from different sources. Besides, successful application of nanoemulsion derived using natural agents for muscle food preservation and shelf life extension are reviewed. Thus, the application of nanoemulsion to extend shelf life and maintain quality is suggested for muscle foods.

Effects of conjugates of ε-polylysine-dextran created through Maillard reaction on quality and storage stability of the chicken gel

The present study mainly focused on the effects of the conjugates of PL-dextran produced through the Maillard reaction on the quality and storage stability of chicken gel for 5 days at 4 ℃. According to the results of the texture profile, water retention capacity (WRC), low-field nuclear magnetic resonance (LF NMR), aerobic plate count (APC), and total volatile basic nitrogen (TVBN), ε-polylysine (PL) could improve chicken gel storage stability while decreasing the quality of protein gels (p < 0.05). Additionally, adding dextran with high or low molecular weight could significantly increase the quality of gel during storage (p < 0.05), whereas decreased storage stability could be obtained (p < 0.05). In general, conjugates formed by PL and dextran with high molecular weight were beneficial for quality maintenance. In comparison, the polymers produced from the low molecular weight of dextran could modify the storage stability of gels. Adding conjugates of dextran and PL benefited the structure formation of protein gel, while PL would retain part of antibacterial activity when crosslinked with dextran. Therefore, it could be concluded that the quality improvement effect of PL-dextran addition on gel quality was greater than its antibacterial effect, which would impact the formulation design of novel emulsion-type meat products.

Development and Application of Dual-Sensors Label in Combination with Active Chitosan-Based Coating Incorporating Yarrow Essential Oil for Freshness Monitoring and Shelf-Life Extension of Chicken Fillet

This study aimed for the application of active chitosan coating incorporating yarrow essential oil (YEO) together with the development of an on-package sensor label based on bromocresol purple (BCP) and methyl red (MR) for shelf-life extension and freshness monitoring of chicken breast fillet. Physiochemical and microbiological attributes of chicken meat coated with sole chitosan, YEO, and chitosan + YEO were compared with those of uncoated (control) samples. Chitosan + YEO coated chicken meat stayed fresh with no significant changes (p > 0.05) in pH (5.42−5.56), TVB-N (12.55−15.36 mg N/100 g), TBARs (0.35−0.40 mg MDA/kg) and total aerobic psycrotrophic bacteria (3.97−4.65 log CFU/g) in days 1−15. There was no response of the dual-sensors label toward the variation in chemical and microbiological indicators of chicken meat coated with chitosan + YEO. However, either uncoated, sole chitosan, or sole YEO treatments indicated a three-stage freshness status with the fresh stage belonged to a period earlier than day 7 (with no distinct color change in both sensor labels); the semi-fresh stage corresponded to storage days between 7−9, wherein a gradual color change appeared (MR from pink to orange, BCP from yellow to light purple); and the spoiled stage occurred in day 9 onward with a drastic color change (MR from orange to light yellow, BCP from light purple to deep purple). In general, the dual-sensors successfully responded to the variation of chemical and microbiological indicators and visual color of uncoated samples during storage time. Based on the obtained results, the application of chitosan + YEO coating efficiently prolonged the freshness of chicken breast meat, where on-package dual-sensors systems were able to detect the freshness stages of meat samples during storage time.

Impacts of Nano-Gelatin Coating Containing Thymol and Nisin on Chemical Quality Indices of Rainbow Trout Fillets Stored at 4°C

Background: Seafood such as fish is an integral part of human nutrition and an excellent source of protein. However, their short shelf life is quite challenging for the food industry. Objectives: This study was carried out to investigate the effects of nano-gelatin coating embedded with thymol and nisin on the chemical quality indices of rainbow trout fillets during 16 days of storage at 4°C. Methods: The fillets were randomly divided into six groups, including control (C), gelatin (G), nano-gelatin (NG), nano-gelatin + thymol (NG-T), nano-gelatin + nisin (NG-N), and nano-gelatin + nisin and thymol (NG-T-N). The chemical quality of fish samples was assessed by performing pH, thiobarbituric acid reactive substance (TBARS), peroxide value (PV), free fatty acid (FFA), and total volatile basic nitrogen (TVB-N) analyses every four days. Results: The results revealed the stunning effect of nisin and thymol addition to the nano-gelatin coating on all chemical quality indices. Besides, PV, TBARS, and FFA analyses showed that nano-gelatin containing thymol significantly decreased lipid oxidation in fish fillet samples (P < 0.05). The lowest amounts of PV (8.33 meq oxygen/kg oil), TBARS, and FFA were recorded for NG-T-N. The best results in the TBARS test (P < 0.05) were observed in NG-T-N, followed by NG-T (1.45 and 1.69 mg of malonaldehyde/kg of tissue, respectively), and similar results were recorded for FFA analysis. On day 16, the lowest amounts of TVB-N were measured for NG-T-N, followed by NG-N and NG-T (26.13, 29.86, and 38.26 mg N/100 g, respectively). Both nisin and thymol reduced the TVB-N and increased the shelf life, and the best results were observed in groups treated with nisin and thymol simultaneously. However, the application of gelatin and nano-gelatin coating without nisin and thymol was ineffective in improving the chemical quality of samples, and they must be used with nisin and/or thymol. Conclusions: Gelatin nanogel embedded with thymol and nisin can be utilized to enhance the chemical quality and shelf life of fish fillets.

Impact of microencapsulated Ziziphora tenuior essential oil and orange fiber as natural‐functional additives on chemical and microbial qualities of cooked beef sausage

The aim of the current study was to investigate the suitability of Ziziphora tenuior essential oil (ZEO) as a preservative. For this purpose, the effect of free and microencapsulated ZEO, combined with orange fiber, was determined on the chemical and microbial qualities of cooked beef sausage. In this study, modified starch was used for encapsulation of essential oil, and subsequently, 0.5% ZEO and 1% orange fiber were used for preparing cooked beef sausages during 60 days of storage at 4°C. To assess the microbial quality of samples, total viable count (TVC), psychrophilic count (PSY), and lactic acid bacteria (LAB) were analyzed. Furthermore, peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) were tested to examine lipid oxidation. The most components of ZEO were pulegone (47.12%), isomenthone (14.57%), and 1,8‐cineole (12.84%) according to GC–MS analysis. The reducing power, DPPH radical scavenging activity, MIC, and MBC of ZEO were 16.44 (EC₅₀), 8.36 (IC₅₀), 0.625–2.5, and 1.25–5 mg/ml, respectively. Moreover, sausage containing 0.5% microencapsulated ZEO in combination with 1% orange fiber showed the best results with the following values (p ≤ .05): TVC (3.69 log CFU/g), PSY (3.51 log CFU/g), LAB (3.1 log CFU/g), PV (10.41 meq/kg lipid), and TBARS (3.1 mg MDA/kg). This is due to the antimicrobial and antioxidant properties of microencapsulated essential oil. Therefore, the results of the present study can be applied in the meat industries as a new natural preservation method.

Development and characterization of levan/pullulan/chitosan edible films enriched with ε-polylysine for active food packaging

The levan/pullulan/chitosan edible films, enriched with ε-polylysine, as an antimicrobial agent, were successfully fabricated by the casting method, and their applicability for food packaging was systematically evaluated by several analytical techniques. An increase in the levan/pullulan ratios (ranged from 0:6 to 3:3) in the films showed a decreased water solubility (from 72.21% to 26.64%) and oxygen permeability (from 48.75 × 10^-2 g·mm·m^-2·d^-1·kPa^-1 to 4.45 × 10^-2 g·mm·m^-2·d^-1·kPa^-1), and increased elongation at break (from 10.92% to 46.61%). All the films showed a strong inhibitory effect on two typical food-borne pathogens and good biodegradability in the soil. These films were employed as edible coatings on strawberries, and the storage stability was investigated by means of physical and biochemical parameters. Compared to control, the weight loss, firmness, and total soluble solids of the coated strawberries showed a downward trend. Overall, these findings suggest that the developed edible films could be a potential approach for sustainable active food packaging.

Nanotechnology as a Processing and Packaging Tool to Improve Meat Quality and Safety

Nanoparticles are gaining momentum as a smart tool towards a safer, more cost-effective and sustainable food chain. This study aimed to provide an overview of the potential uses, preparation, properties, and applications of nanoparticles to process and preserve fresh meat and processed meat products. Nanoparticles can be used to reinforce the packaging material resulting in the improvement of sensory, functional, and nutritional aspects of meat and processed meat products. Further, these particles can be used in smart packaging as biosensors to extend the shelf-life of fresh and processed meat products and also to monitor the final quality of these products during the storage period. Nanoparticles are included in product formulation as carriers of health-beneficial and/or functional ingredients. They showed great efficiency in encapsulating bioactive ingredients and preserving their properties to ensure their functionality (e.g., antioxidant and antimicrobial) in meat products. As a result, nanoparticles can efficiently contribute to ensuring product safety and quality whilst reducing wastage and costs. Nevertheless, a wider implementation of nanotechnology in meat industry is highly related to its economic value, consumers' acceptance, and the regulatory framework. Being a novel technology, concerns over the toxicity of nanoparticles are still controversial and therefore efficient analytical tools are deemed crucial for the identification and quantification of nanocomponents in meat products. Thus, migration studies about nanoparticles from the packaging into meat and meat products are still a concern as it has implications for human health associated with their toxicity. Moreover, focused economic evaluations for implementing nanoparticles in meat packaging are crucial since the current literature is still scarce and targeted studies are needed before further industrial applications.

Bee pollen powder as a functional ingredient in frankfurters

The objective of this study was to determine whether the addition of different pollen powder concentrations (0.0, 0.5, 1.0 and 1.5 g/100 g) to frankfurters had an influence on antioxidant potential and oxidative changes during storage, without detrimental effect on the quality of sausages. After cold storage of frankfurters, significant (P < 0.05) reductions of psychrotrophic bacteria populations were achieved with higher amounts of pollen (1.0 and 1.5 g/100 g). Good antioxidant properties and maintained TBARS values were accomplished by incorporating pollen into the frankfurters. In terms of quality parameters, statistically significant changes were obtained regarding the color, but sensory characteristics of the products were not disturbed. Also, the incorporation of pollen did not cause changes in terms of texture profile analyses of frankfurters. It can be concluded that the natural component, bee pollen powder, can be used as an antioxidant in frankfurter formulations, but further research is needed to estimate whether it can be an adequate replacement for synthetic antioxidants.

Antimicrobial Polyamide-Alginate Casing Incorporated with Nisin and ε-Polylysine Nanoparticles Combined with Plant Extract for Inactivation of Selected Bacteria in Nitrite-Free Frankfurter-Type Sausage

The effects of combining a polyamide-alginate casing incorporated with nisin (100 ppm and 200 ppm) and ε-polylysine (500 ppm and 1000 ppm) nanoparticles and a mixed plant extract as ingredient in sausage formulation (500 ppm; composed of olive leaves (OLE), green tea (GTE) and stinging nettle extracts (SNE) in equal rates) were studied to improve the shelf life and safety of frankfurter-type sausage. The film characteristics and microbiological properties of sausage samples were evaluated. Sausage samples were packaged in polyethylene bags (vacuum condition) and analysed during 45 days of storage at 4 °C. Control sausages were also treated with 120 ppm sodium nitrite. Polyamide-alginate films containing 100 ppm nisin and 500 ε-PL nanoparticles had the highest ultimate tensile strength compared to other films. However, 100 ppm nisin and 500 ε-PL nanoparticles decreased water vapour permeability of films. The results also revealed that nisin nanoparticles had significantly (p < 0.05) low inhibitory effects against Escherichia coli, Staphylococcus aureus, molds and yeasts and total viable counts compared to control and ε-PL nanoparticles. Furthermore, 1000 ppm ε-PL nanoparticles displayed the highest antimicrobial activity. Based on the obtained results, the films containing ε-PL nanoparticle could be considered as a promising packaging for frankfurter-type sausages.

Effect of Aloysia citrodora Essential Oil on Biochemicals, Antioxidant Characteristics, and Shelf Life of Strawberry Fruit during Storage

Strawberry fruits are highly susceptible to cold burning, resulting in low storage periods at low temperatures. Plant extracts or essential oils (EOs) can potentially be used as preservatives in fruits throughout the refrigerated period. In the present study, the biochemicals, antioxidant characteristics, and shelf life of treated strawberries with Aloysia citrodora essential oil (ACEOs) were evaluated during keeping time. The treatments were produced as follows: T1, control; T2, 250 ppm ACEOs; T3, 500 ppm ACEOs; and T4, 750 ppm ACEOs. Total soluble solids (TSS), weight loss, titratable acidity (TA), antioxidant activity (DPPH assay), total phenolic (TPC), flavonoid and anthocyanin contents (TFC), and enzymes activity (peroxidase and ascorbate peroxidase) were evaluated during the refrigerated period (5 °C with relative humidity of 85–90% for 20 days). The results revealed that weight loss and TA were reduced in all treatments during storage, being that the rates were lower in samples treated with ACEOs. TPC, TFC, TSS, antioxidant, and enzymes activity were higher in treated fruits than control.

Antioxidant, Antidiabetic, and Antiobesity Properties, TC7-Cell Cytotoxicity and Uptake of Achyrocline satureioides (Marcela) Conventional and High Pressure-Assisted Extracts

The growing incidence of non-communicable diseases makes the search for natural sources of bioactive compounds a priority for such disease prevention/control. Achyrocline satureioides (‘marcela’), a plant rich in polyphenols and native to Brazil, Uruguay, Paraguay, and Argentina, could be used for this purpose. Data on its antidiabetic/antiobesity properties and cellular uptake of bioactive compounds are lacking. The potentiality of non-thermal technologies such as high-hydrostatic pressure (HP) to enhance polyphenol extraction retains attention. Thus, in the present study aqueous and ethanolic marcela extracts with/without assisted-HP processing were chemically characterized and assessed for their in vitro antioxidant capacity, antidiabetic and antiobesity activities, as well as cellular cytotoxicity and uptake on intestinal cell monolayers (TC7-cells, a clone of Caco-2 cells). Aqueous and ethanolic conventional extracts presented different polyphenolic profiles characterized mainly by phenolic acids or flavonoids, respectively, as stated by reverse phase-high-performance liquid chromatography (RP-HPLC) analyses. In general, ethanolic extracts presented the strongest bioactive properties and HP had none or a negative effect on in vitro bioactivities comparing to conventional extracts. TC7-cell viability and cellular uptake demonstrated in conventional and HP-assisted extracts, highlighted the biological effects of marcela bioactive compounds on TC7-cell monolayers. TC7-cell studies showed no HP-induced cytotoxicity. In sum, marcela extracts have great potential as functional ingredients for the prevention/treatment of chronic diseases such as diabetes.

Efficacy of stinging nettle extract in combination with ε-polylysine on the quality, safety, and shelf life of rainbow trout fillets

The effects of incorporation of stinging nettle extract (3% and 6%) and ɛ-polylysine (0.1% and 0.2%) on chemical, microbial properties, and stability of rainbow trout fish fillets wrapped in polyethylene bags (in atmosphere condition) and refrigerated for 12 days at 4°C were evaluated. No remarkable differences regarding the chemical composition of rainbow trout fish (protein, moisture, fat, and ash content) resulting from the treatments were noted. The lowest TBARS (thiobarbituric acid reactive substance) and the highest phenolic compounds were noted in samples treated with 6% SNE + 0.2% ɛ-PL on day 12, while the highest inhibitory effects against the growth of TVC, psychrotrophic bacteria, coliform, yeast, and molds corresponded to samples treated with 6% SNE (T4 and T5) at day 12. During the storage, the samples' TVB-N (total volatile base nitrogen) increased, whereas the total phenolic content of the rainbow trout samples declined. The rainbow trout samples treated with 6% SNE + 0.2% ɛ-PL had the highest amount of redness and the lowest TVB-N values. Therefore, these natural ingredients could be used to maintain rainbow trout meat quality and shelf life.

Effect of Chitosan Coating Incorporated with Artemisia fragrans Essential Oil on Fresh Chicken Meat during Refrigerated Storage

The present study was conducted to assess the impact of chitosan coating (1%) containing Artemisia fragrans essential oil (500, 1000, and 1500 ppm) as antioxidant and antimicrobial agent on the quality properties and shelf life of chicken fillets during refrigerated storage. After packaging meat samples, physicochemical, microbiological, and organoleptic attributes were evaluated at 0, 3, 6, 9, and 12 days at 4 °C. The results revealed that applied chitosan (CH) coating in combination with Artemisia fragrans essential oils (AFEOs) had no significant (p < 0.05) effects on proximate composition among treatments. The results showed that the incorporation of AFEOs into CH coating significantly reduced (p < 0.05) pH, thiobarbituric acid reactive substances (TBARS), and total volatile base nitrogen (TVB-N), especially for 1% CH coating + 1500 ppm AFEOs, with values at the end of storage of 5.58, 1.61, and 2.53, respectively. The coated samples also displayed higher phenolic compounds than those obtained by uncoated samples. Coated chicken meat had, significantly (p < 0.05), the highest inhibitory effects against microbial growth. The counts of TVC (total viable counts), coliforms, molds, and yeasts were significantly lower (p < 0.05) in 1% CH coating + 1500 ppm AFEOs fillets (5.32, 3.87, and 4.27 Log CFU/g, respectively) at day 12. Organoleptic attributes of coated samples also showed the highest overall acceptability scores than uncoated ones. Therefore, the incorporation of AFEOs into CH coating could be effectively used for improving stability and shelf life of chicken fillets during refrigerated storage.

Packaging of beef fillet with active chitosan film incorporated with ɛ-polylysine: An assessment of quality indices and shelf life

In the current study, the effect on packaged beef fillets (1 × 5 × 8 cm) of using active chitosan film (1%) was investigated. The fillets were stored at 4 °C for 12 days, and the film contained ɛ-polylysine (ɛ-PL) (0.3, 0.6, and 0.9% w/w). Chemical, microbiological, sensory properties, and quality indices of the fillets were investigated. Added to these factors was an assessment of the influence of ɛ-polylysine incorporation on the optical, structural, barrier, and mechanical specifications (elongation at break and tensile strength) of chitosan films. Based on the findings, a significant difference among the corresponding values to thickness, color, water vapor permeability (WVP), and mechanical specifications between the treated films by ɛ-PL and untreated films were noted. In addition, higher values of thickness and tensile strength were correlated with ɛ-PL added active chitosan films while compared with control samples. Additionally, no significant differences regarding the proximate composition (including protein, moisture, and fat) among beef fillet samples were observed. In this regard, due to significantly lower levels of pH, TVB-N, and TBARS ɛ-PL in enriched films, this technique demonstrated some protective effects on beef fillets. Another observation was that lower levels of the total viable count, coliform, mold, yeasts, and higher sensory properties were significantly associated with samples with added ɛ-PL (0.9%). Therefore, adding ɛ-PL into chitosan films could be introduced as an effective technique to extend the shelf life of beef fillets and maintain their quality indices during refrigerated storage.

ɛ-polylysine coating with stinging nettle extract for fresh beef preservation

Combination effects of ɛ-polylysine coating (0.5 and 1%) and stinging nettle extract (3, 6 and 9%) on quality properties and shelf life of beef meat (2 × 2 × 2 cm) was evaluated at 4 °C for 12 days. The results indicated that ɛ-polylysine (ε-PL) coating with stinging nettle extract (SNE) had no significant effects on ash, fat, protein and moisture content among packaged beef samples in polyethylene bags (in atmosphere condition). At the end of storage, beef samples coated with 1% ε-PL and 9% SNE had significantly lower TBARS and TVB-N values compared to those found in control. Furthermore, 1% ε-PL coating with SNE 9% showed the highest inhibitory effects against molds and yeast, total viable counts (TVC) and coliforms during storage. However, sensory evaluation showed that samples coated with 1% ε-PL and 6% SNE had the highest scores for overall acceptability compared to the other groups. Based on the obtained results, ε-PL coating with SNE could be effectively used for extending the beef meat shelf life without negative effects on sensory attributes.