Effect of processing parameters on physicochemical characteristics of microfluidized lemongrass essential oil-alginate nanoemulsions

Emerging encapsulation strategies for vitamin A fortification in food sector: an overview

Micro- and nano-encapsulation techniques, such as microfluidization, spray drying, and centrifugal extrusion, have been widely utilized in various industries, including pharmaceuticals, food, cosmetics, and agriculture, to improve the stability, shelf life, and bioavailability of active ingredients, such as vitamin A. Emulsion-based delivery platforms offer feasible and appropriate alternatives for safeguarding, encapsulating, and transporting bioactive compounds. Therefore, there is a need to enrich our basic diet to prevent vitamin A deficiency within a population. This review focused on addressing vitamin A shortages, encapsulation techniques for improving the delivery of vital vitamins A and their food applications. Additionally, more studies are required to guarantee the security of nano-delivery strategies, as they proliferate in the food and beverage sector.

Graphical Abstract

Encapsulated Thuja plicata essential oil into biopolymer matrix as a potential pesticide against Phytophthora root pathogens

A new formulation that gradually released encapsulated Thuja plicata essential oil (TPEO) as an active component from a biopolymer matrix within a given period was obtained. Antimicrobial activity was determined in in-vitro tests where pure TPEO successfully inhibited the development of different Phytophthora species. The TPEO essential oil was encapsulated into the biopolymer matrix and an oil-in-water emulsion was formed. FTIR spectra analysis confirmed the formation of electrostatic interaction between these polymers, and hydrogen interactions between active components of TPEO and polymer chains. The stability of the emulsions was confirmed by zeta potential measurements, with a value of about 30 mV, even after 14 days of aging. UV-Vis spectra analysis revealed that >60 % of TPEO remained in the emulsion after 14 days of exposure to ambient conditions, whereas pure TPEO evaporated faster, and around 20 % remained after 6 days. Encapsulated TPEO almost completely inhibited the growth of Phytophthora species during the ten-day day's exposition being statistically significantly improved compared to fungicide treatment. It was demonstrated that the emulsion exhibited a prolonged antimicrobial effect and successfully suppressed the growth of Phytophthora species, and can be considered as a means of protection in forests and crops.

Essential oil nanoemulsion: An emerging eco-friendly strategy towards mosquito control

Mosquito borne diseases are impeding to human health due to their uncontrolled proliferation. Various commercial insecticides currently used become ineffective due to the resistance acquired by mosquitoes. It is necessary and a priority to combat mosquito population. Plant-based products are gaining interest over the past few decades due to their environment friendliness and their effectiveness in controlling mosquitoes along with their lack of toxicity. Essential oil nanoemulsions are found to be highly effective when compared to their bulk counterparts. Due to their nano size, they can effectively interact and yield 100 % mortality with the mosquito larvae and encounter with minimal concentrations. This is the main advantage of the nano-sized particles due to which they find application in various disciplines and have also received the attention of researchers globally. There are various components present in essential oils that have been analysed using GC-MS. These findings reflect the challenge to mosquitoes to gain resistance against each component and therefore it requires time. Commercially used repellants are synthesised using materials like DEET are not advisable for topical application on human skin and essential oil nanoemulsions could be an ideal non toxic candidate that can be used against mosquito adults and larvae. However, there are other synthesis, optimisation parameters, and toxicity towards non-target organisms that have to be taken into account when essential oil nanoemulsions are considered for commercial applications. Here we review the strategies used by the nanoemulsions against the mosquito population. Apart from the positive effects, their minor drawbacks also have to be scrutinised in the future.

Nanoemulsions of red quinoa and ginseng extracts with chitosan wall: Investigating the antioxidant properties and its effect on the shelf life of dairy cream

The study aimed to investigate the antioxidant properties of ginseng and red quinoa extract nanoemulsion and its effect on the shelf life of dairy cream. Nanoemulsion includes dairy cream, Tween 80, chitosan, whey protein powder, chitosan/whey protein powder, red quinoa extract, ginseng extract, and a mixture of extracts (1:1). The highest total phenol content and total flavonoid content were related to ginseng extract (24,009.55 mg of gallic acid equivalent/kg, 883.16 mg quercetin/kg) with ethanol-water solvent (80:20). Most of the phenolic and flavonoid compounds of ginseng and red quinoa extracts were related to p-coumaric acid (211.3 μg/g), catechin (29.6 μg/g), ellagic acid (73.88 μg/g), and rutin (34.12 μg/g), respectively. Considerable antioxidant power in the concentration of 800 ppm of red quinoa and ginseng extracts (ethanol-water solvent (50:50), (80:20)) in 2,2-diphenyl-1-picrylhydrazyl radical scavenging (80%, 82%, 80%, and 78%), bleaching β-carotene: linoleic acid (81%, 73%, 77%, and 86%), and ferric reducing antioxidant power assays (70%, 73%, 72%, and 76%) was observed. Nanoemulsions of red quinoa extract with chitosan wall had the smallest particle size (250.67 nm), the highest encapsulation efficiency (72.79%), and the polydispersity index (0.34). Nanoemulsions containing ginseng + quinoa (1:1) with chitosan/whey protein powder wall showed the highest viscosity (5.30 mPa/s) and the mostzeta potential (-32.6 mv). Also, nanoemulsions of red quinoa extract showed the lowest amount of peroxide value and the thiobarbituric acid value (12 milliequivalent O2/kg-0.48 μg/mL) in dairy cream oil. In general, the red quinoa extract with chitosan wall was superior to other samples due to the delay in oxidation and positive effect on the shelf life of dairy cream.

Effect of Microfluidization on the Volatiles and Antibacterial, Antifungal, and Cytotoxic Activities of Algerian Satureja hortensis L. Oil-Loaded Nanoemulsions: In Vitro and In Silico Study

This study aimed to increase the stability and solubility of the Algerian Satureja hortensis L. (ASHO) essential oil through nanoencapsulation. Nanoemulsions of ASHO (MF-ASHEO) were developed to evaluate their antioxidant and antimicrobial potential, stability, and cytotoxicity using microfluidization at 150 MPa for five cycles. MF-ASHO showed 8 compounds (99.56%) vs ASHEO's 26 compounds (95.46%). Carvacrol increased to 94.51%, replacing γ-terpinene, which decreased to 0.43%. The MF-ASHEO nanoemulsion had a mean particle size of 41.72 nm, a monomodal size distribution pattern, a mean ζ-potential of -39.4 mV, and a polydispersity index (PDI) mean value of 0.291. Micrographs showed spherical nanoparticles with varying diameters in nm. ASHEO was more toxic than MF-ASHEO against HepG2, Vero, and WI-38, according to the MTT and WST-1 assays. ASHEO demonstrated antiradical and antibacterial activity and inhibited biofilm formation. It also had an enhanced antifungal effect and reduced mycotoxin production. The MF-ASHEO sample showed no activity except in reducing mycotoxin production, where it performed better than ASHEO. In silico and ADME results confirmed the inhibitory action of carvacrol on the key enzymes of the aflatoxin biosynthetic mechanism and the target proteins associated with bactericidal/bacteriostatic effects. The microfluidization process dramatically affects not only the oil's volatile content but also its biological activity.

Antimicrobial activity of chitosan- edible films containing a combination of carvacrol and rosemary nano-emulsion against Salmonella enterica serovar Typhimurium and Listeria monocytogenes for ground meat

This research aimed to assess the potential of active food packaging as an innovative approach to enhance the quality of fresh food products. Specifically, our focus was on developing chitosan edible films combined with rosemary nanoemulsion (Ch-RNE) and carvacrol nano-emulsion (Ch-CNE) as effective antibacterial food packaging solutions. The efficacy of these films against artificially inoculated L. monocytogenes (NCTC 13372\ ATCC® 7644) as a Gram-positive bacterium, and S. enterica serovar Typhimurium (ATCC 14028) as a Gram-negative bacterium, in ground meat was investigated. The size of the prepared nano-emulsions was characterized using zeta sizer, FTIR and HRTEM. The MIC of both nano-emulsions against both pathogens was found to be 0.78 % and 1.56 %. Filmogenic mixtures were casted using these concentrations, which were then dried and evaluated for their physical and mechanical properties.

Delivery systems designed to enhance stability and suitability of lipophilic bioactive compounds in food processing: A review

Lipophilic compounds, such as flavors, fat-soluble vitamins, and hydrophobic nutrients possess vital properties including antioxidant effects, functional attributes, and nutritional value that can improve human health. However, their susceptibility to environmental factors including heat, pH changes, and ionic strength encountered during food processing poses significant challenges. To address these issues, diverse bioactive delivery systems have been developed. This review explores delivery systems designed to optimize the stability and suitability of lipophilic bioactive compounds in food processing. Extensive literature analysis reveals that tailoring delivery systems with various biopolymers can protect bioactives through steric hindrance and formation of thick interfacial layers on the emulsion surfaces. Thus, the access of oxygen, prooxidants, and free radicals at the emulsion interface could be inhibited, resulting in enhanced processing suitability of bioactives as well as chemical stability under diverse environmental conditions. The insights presented in this review hold immense value for the food and beverage industries.

Synthesis and characterisation of Mānuka and rosemary oil-based nano-entities and their application in meat

Mānuka (MO) and rosemary oils (RO) -containing nanoemulsions and nanocapsules made of sodium alginate and whey protein, were designed and compared for their antioxidant effect. Mānuka oil-nanoemulsions and nanocapsules had smaller particle sizes (343 and 330 nm), less negative zeta potential (-12 mV and -10 mV), higher phenolic content, and antiradical characteristics than RO-nano-entities. However, nano-entities of both oils showed more thermostability and sustained release than free oils. Further, the antioxidant effect of essential oils and their nano-entities was compared against sodium nitrite (SN)-added and without antioxidants-added (controls) and Wagyu and crossbred beef pastes (14 days refrigerated storage). No significant difference among MO, RO and their nano-entities was noticed in crossbred pastes, while in Wagyu, nanoemulsions showed the lowest oxidation values than controls and SN-added pastes. Hence, nano-entities can be alternatives to chemical preservatives as natural antioxidants in meat preservation, along with improved thermal stability and release than free oils.

Development, characterization and use of rosemary essential oil loaded water-chestnut starch based nanoemulsion coatings for enhancing post-harvest quality of apples var. Golden delicious

The study aimed at evaluating the influence of water-chestnut starch-based coatings loaded with rosemary essential oil (REO) at concentrations of 0.10%, 0.25% and 0.50% (w/v) on postharvest cold storage stability of apple var. Golden delicious for 120 days. Average droplet diameter of nanoemulsions was in range of 315-450 nm and it increased with increase in the REO concentration. Minimum weight loss was observed in fruits treated with coating material containing 0.50% REO. Samples coated with starch+0.50% REO exhibited highest firmness value of 68.22 ± 1.02 N under controlled atmosphere storage (CAS). Anthocyanins, ascorbic acid, total phenolic content and antioxidant activity were retained in all samples coated with formulated emulsion. Antifungal assay against Pencillium expansum indicated that 0.50% REO had maximum antifungal activity. Increase in REO concentration from 0.10 to 0.50% in starch coating formulations resulted in reduced lesion diameter in coated samples under both the storage conditions. Lesion diameter (LD) was found highest in control (39.40 ± 0.20 mm) under ambient conditions. Coated fruit samples showed a significant (p≤0.05) reduction in LD under both the ambient and CAS conditions however, more pronounced effect was reported under CAS. Fruits coated with edible coatings enriched with different REO concentrations under CAS exhibited significantly (p≤0.05) lower chilling injury index (ST+0.50%REO < ST+0.25%REO<0.10%REO) compared to control.

Microfluidizing Technique Application for Algerian Cymbopogon citratus (DC.) Stapf Effects Enhanced Volatile Content, Antimicrobial, and Anti-Mycotoxigenic Properties

Medicinal plant extracts are a promising source of bioactive minor contents. The present study aimed to evaluate the distinguished volatile content of Algerian Cymbopogon citratus (DC.) Stapf before and after the microfluidization process and their related antimicrobial and anti-mycotoxigenic impacts and changes. The GC-MS apparatus was utilized for a comparative examination of Algerian lemongrass essential oil (LGEO) with its microfluidization nanoemulsion (MF-LGEO) volatile content. The MF-LGEO was characterized using Zetasizer and an electron microscope. Cytotoxicity, antibacterial, and antifungal activities were determined for the LGEO and MF-LGEO. The result reflected changes in the content of volatiles for the MF-LGEO. The microfluidizing process enhanced the presence of compounds known for their exceptional antifungal and antibacterial properties in MF-LGEO, namely, neral, geranial, and carvacrol. However, certain terpenes, such as camphor and citronellal, were absent, while decanal, not found in the raw LGEO, was detected. The droplet diameter was 20.76 ± 0.36 nm, and the polydispersity index (PDI) was 0.179 ± 0.03. In cytotoxicity studies, LGEO showed higher activity against the HepG2 cell line than MF-LGEO. Antibacterial LGEO activity against Gram-positive bacteria recorded an inhibitory zone from 41.82 ± 2.84 mm to 58.74 ± 2.64 mm, while the zone ranged from 12.71 ± 1.38 mm to 16.54 ± 1.42 mm for Gram-negative bacteria. Antibacterial activity was enhanced to be up to 71.43 ± 2.54 nm and 31.54 ± 1.01 nm for MF-LGEO impact against Gram-positive and Gram-negative pathogens. The antifungal effect was considerable, particularly against Fusarium fungi. It reached 17.56 ± 1.01 mm and 13.04 ± 1.37 mm for LGEO and MF-LGEO application of a well-diffusion assay, respectively. The MF-LGEO was more promising in reducing mycotoxin production in simulated fungal growth media due to the changes linked to essential compounds content. The reduction ratio was 54.3% and 74.57% for total aflatoxins (AFs) and ochratoxin A (OCA) contents, respectively. These results reflect the microfluidizing improvement impact regarding the LGEO antibacterial, antifungal and anti-mycotoxigenic properties.

Food matrix design can influence the antimicrobial activity in the food systems: A narrative review

Antimicrobial agents are safe preservatives having the ability to protect foods from microbial spoilage and extend their shelf life. Many factors, including antimicrobials' chemical features, storage environments, delivery methods, and diffusion in foods, can affect their antimicrobial activities. The physical-chemical characteristics of the food itself play an important role in determining the efficacy of antimicrobial agents in foods; however the mechanisms behind it have not been fully explored. This review provides new insights and comprehensive knowledge regarding the impacts of the food matrix, including the food components and food (micro)structures, on the activities of antimicrobial agents. Studies of the last 10 years regarding the influences of the food structure on the effects of antimicrobial agents against the microorganisms' growth were summarized. The mechanisms underpinning the loss of the antimicrobial agents' activity in foods are proposed. Finally, some strategies/technologies to improve the protection of antimicrobial agents in specific food categories are discussed.

Chia Oil and Mucilage Nanoemulsion: Potential Strategy to Protect a Functional Ingredient

Nanoencapsulation can increase the stability of bioactive compounds, ensuring protection against physical, chemical, or biological degradations, and allows to control of the release of these biocompounds. Chia oil is rich in polyunsaturated fatty acids-8% corresponds to omega 3 and 19% to omega 6-resulting in high susceptibility to oxidation. Encapsulation techniques allow the addition of chia oil to food to maintain its functionality. In this sense, one strategy is to use the nanoemulsion technique to protect chia oil from degradation. Therefore, this review aims to present the state-of-the-art use of nanoemulsion as a new encapsulation approach to chia oil. Furthermore, the chia mucilage-another chia seed product-is an excellent material for encapsulation due to its good emulsification properties (capacity and stability), solubility, and water and oil retention capacities. Currently, most studies of chia oil focus on microencapsulation, with few studies involving nanoencapsulation. Chia oil nanoemulsion using chia mucilage presents itself as a strategy for adding chia oil to foods, guaranteeing the functionality and oxidative stability of this oil.

Impact of Longkong Pericarp Extract on the Physicochemical Properties of Alginate-Based Edible Nanoparticle Coatings and Quality Maintenance of Shrimp (Penaeus monodon) during Refrigerated Storage

The objective of this study was to evaluate the impact of varying concentrations of longkong pericarp extract (LPE) on the physicochemical properties of alginate-based edible nanoparticle coatings (NP-ALG) on shrimp. For developing the nanoparticles, the alginate coating emulsion with different LPE concentrations (0.5, 1.0, and 1.5%) was ultrasonicated at 210 W with a frequency of 20 kHz for 10 min and a pulse duration of 1s on and 4 off. After that, the coating emulsion was separated into four treatments (T): T1: Coating solution containing basic ALG composition and without the addition of LPE or ultrasonication treatment; T2: ALG coating solution converted into nano-sized particles with ultrasonication and containing 0.5% LPE; T3: ALG coating solution converted into nano-sized particles with ultrasonication and containing 1.0% LPE; T4: ALG coating solution converted into nano-sized particles with ultrasonication and containing 1.5% LPE. A control (C) was also used, where distilled water was used instead of ALG coating. Before coating the shrimp, all the coating materials were tested for pH, viscosity, turbidity, whiteness index, particle size, and polydispersity index. The control samples had the highest pH and whiteness index and was followed by the lowest viscosity and turbidity (p < 0.05). Among the T1-T4 coating materials, T4 coating had higher turbidity, particle size, polydispersity index, but lower pH, viscosity, and whiteness index (p < 0.05). To study the quality and shelf-life of the shrimp, all coated shrimp samples were refrigerated at 4 °C for a period of 14 days. At 2-day intervals, physiochemical and microbial analyses were performed. The coated shrimp also had a lower increase in pH and weight loss over the storage period (p < 0.05). Coatings containing 1.5% LPE significantly reduced the polyphenol oxidase activity in the shrimp (p > 0.05). The addition of LPE to NP-ALG coatings demonstrated dose-dependent antioxidant activity against protein and lipid oxidation. The highest LPE concentration (1.5%) led to increased total and reactive sulfhydryl content, along with a significant decrease in carbonyl content, peroxide value, thiobarbituric acid reactive substances, p-anisidine, and totox values at the end of the storage period (p < 0.05). Additionally, NP-ALG-LPE coated shrimp samples exhibited an excellent antimicrobial property and significantly inhibited the growth of total viable count, lactic acid bacteria, Enterobacteriaceae, and psychotropic bacteria during storage. These results suggested that NP-ALG-LPE 1.5% coatings effectively maintained the quality as well as extended the shelf-life of shrimp during 14 days of refrigerated storage. Therefore, the use of nanoparticle-based LPE edible coating could be a new and effective way to maintain the quality of shrimp during prolonged storage.

Structural and Physicochemical Characterization of Extracted Proteins Fractions from Chickpea (Cicer arietinum L.) as a Potential Food Ingredient to Replace Ovalbumin in Foams and Emulsions

Chickpeas are the third most abundant legume crop worldwide, having a high protein content (14.9-24.6%) with interesting technological properties, thus representing a sustainable alternative to animal proteins. In this study, the surface and structural properties of total (TE) and sequential (ALB, GLO, and GLU) protein fractions isolated from defatted chickpea flour were evaluated and compared with an animal protein, ovalbumin (OVO). Differences in their physicochemical properties were evidenced when comparing TE with ALB, GLO, and GLU fractions. In addition, using a simple and low-cost extraction method it was obtained a high protein yield (82 ± 4%) with a significant content of essential and hydrophobic amino acids. Chickpea proteins presented improved interfacial and surface behavior compared to OVO, where GLO showed the most significant effects, correlated with its secondary structure and associated with its flexibility and higher surface hydrophobicity. Therefore, chickpea proteins have improved surface properties compared to OVO, evidencing their potential use as foam and/or emulsion stabilizers in food formulations for the replacement of animal proteins.

Inhibitory Effect of Sodium Alginate Nanoemulsion Coating Containing Myrtle Essential Oil (Myrtus communis L.) on Listeria monocytogenes in Kasar Cheese

The present study aimed to characterize the physical properties of nanoemulsion-based sodium alginate edible coatings containing myrtle (Myrtus communis L.) essential oil and to determine its inhibitory effects on Listeria monocytogenes in fresh Kasar cheese during the 24-day storage at 4 °C. The GC-MS analysis showed that the main components of myrtle essential oil were 1,8-cineol (38.64%), α-pinene (30.19%), d-limonene (7.51%), and α-ocimene (6.57%). Myrtle essential oil showed an inhibitory effect on all tested L. monocytogenes strains and this effect significantly increased after ultrasonication. Minimum inhibitory and minimum bactericidal concentrations of myrtle essential oil nanoemulsion were found to be 4.00-4.67 mg/mL and 5.00-7.33 mg/mL, respectively. The antibacterial activity of myrtle essential oil nanoemulsion against L. monocytogenes was confirmed by the membrane integrity and FESEM analyses. Nanoemulsion coatings containing myrtle essential oil showed antibacterial activity against L. monocytogenes with no adverse effects on the physicochemical properties of cheese samples. Nanoemulsion coatings containing 1.0% and 2.0% myrtle essential oil reduced the L. monocytogenes population in cheese during the storage by 0.42 and 0.88 log cfu/g, respectively. These results revealed that nanoemulsion-based alginate edible coatings containing myrtle essential oil have the potential to be used as a natural food preservative.

A New Control Strategy for High-Pressure Homogenization to Improve the Safety of Injectable Lipid Emulsions

Intravenous lipid emulsions are biocompatible formulations used as clinical nutrition products and lipid-based delivery systems for sparingly soluble drugs. However, the particle-size distribution is associated with risks of embolism. Accordingly, the mean particle diameter (MPD) and particle-distribution tailing (characterized as the pFAT5 value) are critical quality attributes that ensure patient safety. Compliance with the limits stated in the United States Pharmacopoeia is ensured by high-pressure homogenization, the final step of the manufacturing process. The US Food and Drug Administration’s Quality-by-Design approach requires a control strategy based on deep process understanding to ensure that products have a consistent and predefined quality. Here we investigated the process parameters of a jet-valve high-pressure homogenizer, specifically their effect on the MPD, pFAT5 value and droplet count (determined by microscopy) during the production of a Lipofundin MCT/LCT 20% formulation. We provide deep insight into droplet breakup and coalescence behavior when varying the process pressure, emulsion temperature and number of homogenization cycles. We found that high shear forces are not required to reduce the pFAT5 value of the particle distribution. Finally, we derived a control strategy for a rapid and cost-efficient two-cycle process that ensures patient safety over a large control space.

Characteristics and Antibacterial Effect of Chitosan Coating Nanoemulsion Containing Zataria multiflora and Bunium persicum Essential Oils Against Listeria monocytogenes

Background: Nowadays, finding natural compounds with antimicrobial properties against pathogens is very important, especially for the food and drug industries. Objectives: The antibacterial activity of chitosan coatings nanoemulsion (NE) containing Zataria multiflora and Bunium persicum essential oils (EOs) was evaluated in a food model (chicken breast fillets) during 15 days of refrigerated storage. Methods: The chicken breast fillets were divided into seven groups: control, chitosan 2%, sonicated chitosan 2%, chitosan NE coating containing Z. muitiflora EO (ZMEO, 0.5%, and 1 %) and chitosan NE coating containing B. persicum EO (BPEO, 0.5%, and 1 %). Characteristics of chitosan NE coatings containing EOs were analyzed. Moreover, the antimicrobial activity of coatings against Listeria monocytogenes was investigated. Results: The results showed good properties of the NE coatings. The analysis of EOs revealed that the major components for ZMEO were carvacrol (51.55%) and thymol (25.49%). In addition, the main components of BPEO were p-cumic aldehyde (38.39%) and p-cymene (18.36%). All treatments exhibited antimicrobial properties; however, the best result was recorded for chitosan NE coating containing 1% ZMEO, which was the lowest amount of L. monocytogenes (7.61 Log CFU/g). Moreover, L. monocytogenes analysis for chitosan NE coating containing 1% BPEO samples was 7.73 Log CFU/g. Conclusions: Therefore, based on the results of this study, chitosan NE coating containing ZMEO and BPEO as natural preservatives can be recommended for meat products, especially chicken meats.

Formulation process, physical stability and herbicidal activities of Cymbopogon nardus essential oil-based nanoemulsion

Essential oil-based bioherbicides are a promising avenue for the development of eco-friendly pesticides. This study formulated nanoemulsions containing citronella (Cymbopogon nardus) essential oil (CEO) as an herbicidal product using a high-pressure homogenization method with hydrophilic-lipophilic balance (HLB) values ranging 9–14.9 for the surfactant mixture (Tween 60 and Span 60). The CEO was high in monoterpene compounds (36.333% geraniol, 17.881% trans-citral, 15.276% cis-citral, 8.991% citronellal, and 4.991% β-citronellol). The nanoemulsion at HLB 14 was selected as optimal due to having the smallest particle size (79 nm, PI 0.286), confirmed by transmission electron microscopy. After 28 days of storage, particle size in the selected formulation changed to 58 and 140 nm under 4 °C and 25 °C, respectively. Germination and seedling growth assays with Echinochloa crus-galli showed that the nanoemulsion exerted a significant dose-dependent inhibitory effect at all tested HLBs (9–14.9) and concentrations (100–800 µL/L). The inhibitory effect was greatest at HLB 14. Treatment of E. cruss-galli seed with the HLB 14 nanoemulsion significantly reduced seed imbibition and α-amylase activity. Our findings support that CEO nanoemulsions have a phytotoxic effect and hence herbicidal properties for controlling E. cruss-galli. Accordingly, this nanoemulsion may have potential as a bioherbicide resource.

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.

Protective effect of chitosan-loaded nanoemulsion containing Zataria multiflora Boiss and Bunium persicum Boiss essential oils as coating on lipid and protein oxidation in chill stored turkey breast fillets

The present study was conducted to evaluate the lipid and protein oxidation responses of cold stored turkey meat using chitosan-contained nanoemulsions supplemented with the essential oils of two aromatic plants including Zataria multiflora Boiss and Bunium persicum Boiss. Chemical traits such as total volatile basic nitrogen (TVB-N), peroxide value (PV), thiobarbituric reactive substances (TBARs), free fatty acids (FFA), fatty acid composition and TC (total carbonyl) of samples were carried out at 4°C. Moreover, their pH and sensory properties were also determined at the same conditions. The initial value of the TVB-N (2.24 mg N/100 g) reached 20.81 mg N/100 g. TVB-N values achieved for all meat samples were lower than the highest acceptable limit (28-29 mg N/100 g). In all the treatments, PV and TBARs values were increased until day 10, and afterward a decrease was observed until day 20 of storage. TBARs values of the samples (mg MDA/kg) ranged from 1.97 ± 0.04 to 4.48 ± 0.39 in CNE + ZEO 1% to 2.72 ± 0.32 to 6.66 ± 0.21 in CON at zero time and day 5, respectively. FFA and TC were enhanced at a slower rate in the treated samples. The most efficient treatment against chemical deterioration was found to be CNE + ZEO 1%. Chitosan and sonicated chitosan treatments had the highest color score and lowest odor score at zero time. The obtained results suggested coating turkey meat fillets with ZEO and BEO as an effective strategy to delay at their chemical deterioration. PRACTICAL APPLICATION: The spoilage risk of fresh products is higher than other foods. Turkey meat spoils because of biological reactions such as the oxidation of lipids and protein, the action of endogenous enzymes, and the metabolic activities of microorganisms that end in a short shelf life. The oxidation of lipids not only reduces or retards, but also inhibits by edible coatings. Edible coatings formed from bioactive compounds would effectively provide possibility of active compounds onto surface of minimally processed foods. Therefore, application chitosan-loaded nanoemulsion coating containing Zataria multiflora Boiss and Bunium persicum Boiss essential oils is recommended in food industry especially for poultry industry to increase the chemistry and sensory quality of turkey breast fillets.

Nanoemulsion-based basil seed gum edible film containing resveratrol and clove essential oil: In vitro antioxidant properties and its effect on oxidative stability and sensory characteristic of camel meat during refrigeration storage

The initial purpose of this study was to compare the in vitro antioxidant interactions between resveratrol (RES) and clove essential oil (CEO) in conventional and nanoemulsion-based basil seed gum (BSG) films. Then, the effects of the best nanoemulsion-based BSG film obtained from in vitro evaluations were determined on oxidative stability and sensory properties of minced camel meat during 20-day storage at 4 °C. The results showed higher in vitro antioxidant activities of nanoemulsion-based BSG films compared to conventional films as well as synergistic effects between RES and CEO. Furthermore, minced camel meat wrapped with nanoemulsion-based BSG film containing RES 4 μg/mL + CEO 10 mg/mL showed better results compared with the control group with the following scores: total carbonyls (0.84 nmol/mg protein), peroxide value (4.03 meq/kg lipid), thiobarbituric acid reactive substance (1.03 mg malondialdehyde/kg), and sensory analysis (overall acceptability: 5.4). The finding of the present study can be applied as a new method in meat and meat products packaging industry.

Enhancing safety and quality of shrimp by nanoparticles of sodium alginate-based edible coating containing grapefruit seed extract

Edible coatings are safe and effective in extending the shelf life of foods. In this study, a nanoparticle-based edible coating solution was prepared, containing alginate as a coating agent and grapefruit seed extract as an antibacterial agent to improve the safety and quality of shrimp during storage. Shrimp coated with this formulation were maintained at 4°C for 8 days, and periodically analyzed for changes in sensory, chemical [total volatile basic nitrogen (TVB-N) and pH] and microbial parameters. The uncoated shrimp exceeded the microbiological limits at 7.87 log CFU/g on Day 4 of storage, whereas the nanoparticle-based coated shrimp did not exceed the limit by Day 8 of storage. In addition, uncoated shrimp tended to maintain their quality, while uncoated shrimp deteriorated due to increased TVB-N values, pH values, and off-flavors. Nanoparticles are easily dispersed in food to minimize flavor impact and enhance diffusion and bioactivity. We concluded that the nanoparticles coating extended the shelf life of shrimp by more than 5 days. Therefore, the use of nanoparticle-based coatings could be a new and effective way to maintain shrimp quality.

The effect of Thymus vulgaris and Thymbra spicata essential oils and/or extracts in pectin edible coating on the preservation of sliced bolognas

The aim of this research was to determine the effect of pectin coating made with essential oils and/or extracts of Thymus vulgaris (thyme) and Thymbra spicata (thymbra) on the preservation of aerobically packaged sliced bolognas during cold storage. The treatment made with essential oils resulted in a reduction of 1.73 log CFU/g of Salmonella typhimurium ATCC 14028. Also, pectin coating made with essential oil-treated sliced bolognas had the lowest total mesophilic bacteria (6.27 log CFU/g), and total lactic acid bacteria (1.72 CFU/g), in comparison to non-treated bolognas, with 7.65 log CFU/g for total mesophilic bacteria and 4.99 log CFU/g for lactic acid bacteria. Application of an emulsion significantly (P < 0.05) affected L*(lightness), a*(redness), and b*(yellowness) values. The essential oil treatment had the highest TBARS values at the end of the storage period. The pH was not affected by the treatment (P > 0.05), but storage had a significant (P < 0.05) effect on the pH values.

Alginate-based delivery systems for food bioactive ingredients: An overview of recent advances and future trends

Due to its advantagessuch as ionic crosslinking, pH responsiveness, excellent biocompatibility, biodegradability and low price, alginate has become one of the most important natural polysaccharides extensively used in constructing desired delivery systems for food bioactive ingredients. In this review, the fundamental knowledge of alginate as a building block for construction of nutraceutical delivery systems is introduced. Then, various types of alginate-based nutraceutical delivery systems are classified and summarized. Furthermore, the future trends of alginate-based delivery systems are highlighted. Currently, alginate-based delivery systems include hydrogel, emulsion, emulsion-filled alginate hydrogel, nanoparticle, microparticle, core-shell particle, liposome, edible film, and aerogel. Although alginate has been widely used in the fabrication of food bioactive ingredient delivery systems, further efforts and improvements are still needed. For this purpose, the future perspectives of alginate-based delivery systems are discussed. The feasible research trends of alginate-based delivery systems include the development of novel large-scale commercial preparation technology, multifunctional delivery system based on alginate, alginate oligosaccharide-based delivery system and alginate-based oleogel. Overall, the objective of this review is to provide useful guidance for rational design and application of alginate-based nutraceutical delivery systems in the future.

The effect of process variables on the physical properties and microstructure of HOPO nanoemulsion flakes obtained by refractance window

Refractance window (RW) drying is considered an emerging technique in the food field due to its scalability, energy efficiency, cost and end-product quality. It can be used for obtaining flakes from high-oleic palm oil (HOPO) nanoemulsions containing a high concentration of temperature-sensitive active compounds. This work was thus aimed at studying the effect of temperature, thickness of the film drying, nanoemulsion process conditions, and emulsion formulation on the flakes’ physical properties and microstructure. The results showed that HOPO flakes had good physical characteristics: 1.4% to 5.6% moisture content and 0.26 to 0.58 a_w. Regarding microstructure, lower fractal dimension (FDt) was obtained when RW drying temperature increased, which is related to more regular surfaces. The results indicated that flakes with optimal physical properties can be obtained by RW drying of HOPO nanoemulsions.

Thymol nanoemulsion promoted broiler chicken's growth, gastrointestinal barrier and bacterial community and conferred protection against Salmonella Typhimurium

The present study involved in vivo evaluation of the growth promoting effects of thymol and thymol nanoemulsion and their protection against Salmonella Typhimurium infection in broilers. One-day old 2400 chicks were randomly divided into eight groups; negative and positive control groups fed basal diet without additives and thymol and thymol nanoemulsion groups (0.25, 0.5 and 1% each). At d 23, all chicks except negative control were challenged with S. Typhimurium. Over the total growing period, birds fed 1% thymol nanoemulsion showed better growth performance even after S. Typhimurium challenge, which came parallel with upregulation of digestive enzyme genes (AMY2A, PNLIP and CCK). Additionally, higher levels of thymol nanoemulsion upregulated the expression of MUC-2, FABP2, IL-10, IgA and tight junction proteins genes and downregulated IL-2 and IL-6 genes expression. Moreover, 1% thymol nanoemulsion, and to lesser extent 0.5% thymol nanoemulsion and 1% thymol, corrected the histological alterations of cecum and liver postinfection. Finally, supplementation of 1% thymol, 0.5 and 1% thymol nanoemulsion led to increased Lactobacilli counts and decreased S. Typhimurium populations and downregulated invA gene expression postinfection. This first report of supplying thymol nanoemulsion in broiler diets proved that 1% nano-thymol is a potential growth promoting and antibacterial agent.

Assessment of Fennel Oil Microfluidized Nanoemulsions Stabilization by Advanced Performance Xanthan Gum

In this work, nanoemulsion-based delivery system was developed by encapsulation of fennel essential oil. A response surface methodology was used to study the influence of the processing conditions in order to obtain monomodal nanoemulsions of fennel essential oil using the microchannel homogenization technique. Results showed that it was possible to obtain nanoemulsions with very narrow monomodal distributions that were homogeneous over the whole observation period (three months) when the appropriate mechanical energy was supplied by microfluidization at 14 MPa and 12 passes. Once the optimal processing condition was established, nanoemulsions were formulated with advanced performance xanthan gum, which was used as both viscosity modifier and emulsion stabilizer. As a result, more desirable results with enhanced physical stability and rheological properties were obtained. From the study of mechanical spectra as a function of aging time, the stability of the nanoemulsions weak gels was confirmed. The mechanical spectra as a function of hydrocolloid concentration revealed that the rheological properties are marked by the biopolymer network and could be modulated depending on the amount of added gum. Therefore, this research supports the role of advanced performance xanthan gum as a stabilizer of microfluidized fennel oil-in-water nanoemulsions. In addition, the results of this research could be useful to design and formulate functional oil-in-water nanoemulsions with potential application in the food industry for the delivery of nutraceuticals and antimicrobials.

A comparative study on the effect of homogenization conditions on the properties of the film-forming emulsions and the resultant films

Emulsions based on licorice essential oil (LEO) were prepared under different homogenization conditions (ultra-homogenization (U1) or U1 together with sonication (U2)). The obtained emulsions were incorporated into the carboxymethyl cellulose (CMC) film. The results showed that U2 caused significant changes in the size and the surface charge of the emulsions. Remarkable differences in the microstructure were observed between the U1 and the U2 emulsion-based films as revealed by SEM and AFM. Both emulsions reduced the rigidity and increased the flexibility of the films. The film made from the CMC alone had a water vapor permeability (WVP) of 2.66 × 10^-9 g m^-1 s^-1 Pa^-1, while the CMC film made from U2 emulsion had a WVP of 1.87 × 10^-9 g m^-1 s^-1 Pa^-1. Also, the film containing 0.0125% U1-LEO exhibited antibacterial activity on gram-positive bacteria only while the film containing 0.0125% U2-LEO demonstrated antibacterial activity on both gram-positive and gram-negative bacteria.

Effect of Cross-Linked Alginate/Oil Nanoemulsion Coating on Cracking and Quality Parameters of Sweet Cherries

The cracking of sweet cherries causes significant crop losses. Sweet cherries (cv. Bing) were coated by electro-spraying with an edible nanoemulsion (NE) of alginate and soybean oil with or without a CaCl2 cross-linker to reduce cracking. Coated sweet cherries were stored at 4 °C for 28 d. The barrier and fruit quality properties and nutritional values of the coated cherries were evaluated and compared with those of uncoated sweet cherries. Sweet cherries coated with NE + CaCl2 increased cracking tolerance by 53% and increased firmness. However, coated sweet cherries exhibited a 10% increase in water loss after 28 d due to decreased resistance to water vapor transfer. Coated sweet cherries showed a higher soluble solid content, titratable acidity, antioxidant capacity, and total soluble phenolic content compared with uncoated sweet cherries. Therefore, the use of the NE + CaCl2 coating on sweet cherries can help reduce cracking and maintain their postharvest quality.

An overview of nanoemulsion characterization via atomic force microscopy

Nanoemulsion-based systems are widely applied in food industries for protecting active ingredients against oxidation and degradation and controlling the release rate of active core ingredients under particular conditions. Visualizing the interface morphology and measuring the interfacial interaction forces of nanoemulsion droplets are essential to tailor and design intelligent nanoemulsion-based systems. Atomic force microscopy (AFM) is being established as an important technique for interface characterization, due to its unique advantages over traditional imaging and surface force-determining approaches. However, there is a gap in knowledge about the applicability of AFM in characterizing the droplet interface properties of nanoemulsions. This review aims to describe the fundamentals of the AFM technique and nanoemulsions, mainly focusing on the recent use of AFM to investigate nanoemulsion properties. In addition, by reviewing interfacial studies on emulsions in general, perspectives for the further development of AFM to study nanoemulsions are also discussed.

Shelf life extension of apricot fruit by application of nanochitosan emulsion coatings containing pomegranate peel extract

The effect of nanochitosan coating containing pomegranate peel extract (PPE) at concentrations 0.5, 0.75 and 1% (w/v) on postharvest quality of apricot fruit was studied during storage at 4 °C for 30 days. Nanoemulsions showed significant increase in droplet diameter 275-400 nm, decrease in zeta potential -30-23 mV and viscosity 90-76 mPas^-1 with increase in PPE concentration. Results confirmed that apricot fruit treated with chitosan and 1% PPE showed significantly reduced decay percentage, weight loss, effectively retained DPPH radical scavenging activity, ascorbic acid, kept titratable acidity and firmness at high level than untreated fruit. Color attributes showed decrease in L*, a* values and significant increase in b* value. Nanochitosan containing 1% PPE significantly inhibited total psychrophilic bacterial count, yeast and mold count during storage. Our results suggest that chitosan coatings enriched with pomegranate peel extract has the potential to preserve the quality and extend shelf life of apricot.

Statistical optimization of photo-induced biofabrication of silver nanoparticles using the cell extract of Oscillatoria limnetica: insight on characterization and antioxidant potentiality

Silver nanoparticles were successfully fabricated through a very simple, rapid, one-step photo-induced green approach. The formation of silver nanoparticles was accomplished using the bioactive compounds in the aqueous extract of fresh Oscillatoria limnetica biomass, which acted as a reducing and capping agent at the same time. The biosynthesis of Oscillatoria-silver nanoparticles (O-AgNPs) was investigated under the influence of different light intensities 57.75, 75.90 and 1276.51 μmol m-2 s-1 (bright sunlight). UV-Vis (UV) and Fourier transform infrared (FT-IR) spectroscopy were applied to approve the synthesis of AgNPs. Further, the synthesis process under the exposure to sunlight was adjusted via utilizing one factor at a time, and 0.5 mM AgNO3 concentration, 5 mL O. limnetica solution, pH 6.7 and 30 min sunlight (1276.51 μmol m-2 s-1) were applied. Furthermore, the central composite design (CCD) was applied to boost the biosynthesis process of O-AgNPs (manufactured at light intensity 75.90 μmol m-2 s-1). The maximum production of O-AgNPs was attained with 4 detected variables: initial pH level (6.7), AgNO3 concentration (0.3 mM), O. limnetica extract concentration (3.50 mL) and incubation time (48 h). Moreover, TEM, in addition to SEM, images exposed that the biosynthesized AgNPs were quasi-spherical in shape with a small monodisperse nature, and the size range was between 6.98-23.48 nm in the case of light-induced synthesis (75.90 μmol m-2 s-1) and 11.58-22.31 nm with sunlight (1276.51 μmol m-2 s-1).

Encapsulation of Lipid-Soluble Bioactives by Nanoemulsions

Lipid-soluble bioactives are important nutrients in foods. However, their addition in food formulations, is often limited by limited solubility and high tendency for oxidation. Lipid-soluble bioactives, such as vitamins A, E, D and K, carotenoids, polyunsaturated fatty acids (PUFA) and essential oils are generally dispersed in water-based solutions by homogenization. Among the different homogenization technologies available, nanoemulsions are one of the most promising. Accordingly, this review aims to summarize the most recent advances in nanoemulsion technology for the encapsulation of lipid-soluble bioactives. Modern approaches for producing nanoemulsion systems will be discussed. In addition, the challenges on the encapsulation of common food ingredients, including the physical and chemical stability of the nanoemulsion systems, will be also critically examined.

Formulation and Application of Nanoemulsions for Nutraceuticals and Phytochemicals

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Recent trends in research and investigation on nanoemulsion based products is the result of many reasons such as food security as a global concern, increasing demand for highly efficient food and agricultural products and technological need for products with the ability of manipulation and optimization in their properties. Nanoemulsions are defined as emulsions made up of nano sized droplets dispersed in another immiscible liquid which exhibit properties distinguishing them from conventional emulsions and making them suitable for encapsulation, delivery and formulations of bioactive ingredients in different fields including drugs, food and agriculture. The objective of this paper is to present a general overview of nanoemulsions definition, their preparation methods, properties and applications in food and agricultural sectors. Due to physicochemical properties of the nanoemulsion composition, creating nanosized droplets requires high/low energy methods that can be supplied by special devices or techniques. An overview about the mechanisms of these methods is also presented in this paper which are commonly used to prepare nanoemulsions. Finally, some recent works about the application of nanoemulsions in food and agricultural sectors along with challenges and legislations restricting their applications is discussed in the last sections of the current study.

Morphology and microstructural analysis of bioactive-loaded micro/nanocarriers via microscopy techniques; CLSM/SEM/TEM/AFM

Efficient characterization of the physicochemical attributes of bioactive-loaded micro/nano-vehicles is crucial for the successful product development. The introduction of outstanding science-based strategies and techniques makes it possible to realize how the characteristics of the formulation ingredients affect the structural and (bio)functional properties of the final bioactive-loaded carriers. The important points to be solved, at a microscopic level, are investigating how the features of the formulation ingredients affect the morphology, surface, size, dispersity, as well as the particulate interactions within bioactive-comprising nano/micro-delivery systems. This review presents a detailed description concerning the application of advanced microscopy techniques, i.e., confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) in characterizing the attributes of nano/microcarriers for the efficient delivery of bioactive compounds. Furthermore, the fundamental principles of these approaches, instrumentation, specific applications, and the strategy to choose the most proper technique for different carriers has been discussed.