Application of nano-encapsulated olive leaf extract in controlling the oxidative stability of soybean oil

Freezing effect on the oleuropein content of olive leaves extracts obtained from microwave-assisted extraction

This work aimed to investigate the effect of freezing on the oleuropein content obtained from olive leaves extracts. The extracts were obtained by microwave-assisted extraction using different solvents, pH, temperatures and microwave irradiation time. Afterward, HPLC was used to identify and quantify the amount of oleuropein in the extracts. A part of the extracts was immediately analyzed, and another was frozen for a week. The experimental results highlighted that the storage condition has a significant (p < 0.05) effect on the oleuropein content. Regardless of the extraction condition, the frozen storage was responsible for a decrease in the oleuropein content, ranging from 5.38 to 70.09%. These results indicate that it is important to consider the degradation of oleuropein in frozen olive leaf extracts so that subsequent applications are suitable.

Olive Leaves (Olea europaea L) Extract Loaded Lipid Nanoparticles: Optimization of Processing Parameters by Box-Behnken Statistical Design, in-vitro Characterization, and Evaluation of Anti-oxidant and Anti-microbial Activity

The present study was aimed to prepare and evaluated solid lipid nanoparticles (SLNs) of olive leaves extract powder (OLP) which contained many anti-oxidant and antimicrobial agents like oleuropein, a natural polyphenol. The major issue concern OLP was the instability due to environmental conditions and hence compromised bioactivity. To overcome this problem, SLNs were designed by hot homogenous followed by sonication technique to protect the drug and improve its antioxidant and antimicrobial activity. Lipids like compritol 888ATO and surfactant like tween 80 were used for the development and stabilization of SLNS and optimization was done by Box-Behnken statistical design (3x3). The optimized batch (F9) showed particle size, entrapment efficiency, PDI, and zeta potential 277.46 nm, 80.48%, 0.275, and －23.18 mV respectively. Optimized formulation (F9) exhibited a sustained release pattern up to 24 h with first-order release kinetic (R² = 0.9984) and the mechanism of drug release was found to be Fickian diffusion type (n = 0.441). Upon the stability study, it could be found that SLNs formulation was stable. Anti-oxidation and anti-microbial studies were conducted on optimized formulation and findings suggested that SLNs showed an improved radical scavenging activity and anti-microbial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria. Finally, it was concluded that developed SLNs were able to protect and suitable for the delivery of OLP.

Influence of diverse natural biopolymers on the physicochemical characteristics of borage seed oil-peppermint oil loaded W/O/W nanoemulsions entrapped with lycopene

Borage seed oil (BSO), peppermint oil (PO) and lycopene (LC) have accomplished a lot of interest due to their therapeutic benefits in the food and pharmaceutical sectors. However, their employment in functional food products and dietary supplements is still precluded by their high susceptibility to oxidation. Thus, the encapsulation can be applied as a promising strategy to overcome these limits. In the present study, doubly layered water/oil/water (W/O/W) nanoemulsions were equipped using purity gum ultra (PGU), soy protein isolate (SPI), pectin (PC), whey protein isolate (WPI) and WPI-PC and SPI-PC complexes, and their physico-chemical properties were investigated. Our aim was to investigate the influence of natural biopolymers as stabilizers on the physicochemical properties of nanoemulsified BSO, PO and lycopene thru W/O/W emulsions. The droplet size of the fabricated emulsions coated with PGU, WPI, SPI, PC, WPI-PC, and SPI-PC was 156.2, 265.9, 254.7, 168.5, 559.5 and 656.1 nm, correspondingly. The encapsulation efficiency of the entrapped bioactives for powders embedded by PGU, WPI, SPI, PC, WPI-PC, and SPI-PC was 95.21%, 94.67%, 97.24%, 92.19%, 90.07% and 92.34%, respectively. In addition, peroxide and p-anisidine values were used to measure the antioxidant potential of the entrapped bioactive compounds during storage, which was compared to synthetic antioxidant and bare natural antioxidant. The collected findings revealed that oxidation occurred in oils encompassing entrapped bioactive compounds, but at a lower extent than for non-encapsulated bioactives. In summary, the findings obtained from current research prove that the nanoencapsulation of BSO surrounded by innermost aqueous stage of W/O/W improved its stability as well as allowed a controlled release of the entrapped bioactives. Thus, the obtained BSO-PO-based systems could be successfully used for further fortification of food-stuffs.

Anti-aging properties of phytoconstituents and phyto-nanoemulsions and their application in managing aging-related diseases

Aging is spontaneous and inevitable process in all living beings. It is a complex natural phenomenon that manifests as a gradual decline of physiological functions and homeostasis. Aging inevitably leads to age-associated injuries, diseases, and eventually death. The research on aging-associated diseases aimed at delaying, preventing or even reversing the aging process are of great significance for healthy aging and also for scientific progress. Numerous plant-derived compounds have anti-aging effects, but their therapeutic potential is limited due to their short shelf-life and low bioavailability. As the novel delivery system, nanoemulsion can effectively improve this defect. Nanoemulsions enhance the delivery of drugs to the target site, maintain the plasma concentration for a longer period, and minimize adverse reaction and side effects. This review describes the importance of nanoemulsions for the delivery of phyto-derived compounds and highlights the importance of nanoemulsions in the treatment of aging-related diseases. It also covers the methods of preparation, fate and safety of nanoemulsions, which will provide valuable information for the development of new strategies in treatment of aging-related diseases.

The Role of Polydimethylsiloxane in Suppressing the Evolution of Lipid Oxidation Products in Thermo-Oxidised Sunflower Oil: Influence of Stirring Processes

Suppressing the evolution of lipid oxidation products (LOPs) in commercially available culinary oils is considered to represent a valuable health-promoting incentive since these agents have cytotoxic and genotoxic properties and have been implicated in the pathogenesis of several chronic disease states. One agent used to suppress LOPs formation is polydimethylsiloxane (PDMS). In this study, proton nuclear magnetic resonance (¹H NMR) analysis was employed to evaluating the influence of increasing PDMS concentrations (6.25 × 10⁻⁷, 1.0 × 10⁻⁵, 0.025, 0.05, 0.1, 0.5, 1.0, 5.0, and 10.0 ppm) in either stirred or unstirred refined sunflower oil exposed to thermal stressing episodes continuously at 180°C for 300 min with no oil replenishment. Results acquired showed that the extent of blockage of LOPs generation was correlated with increasing concentrations of PDMS. The minimal level of added PDMS required to provide a statistically significant protective role for both stirred and unstirred culinary oils when exposed to high frying temperatures was only 6.25 × 10⁻⁷ ppm. Furthermore, stirring at 250 rpm was experimentally determined to reduce the functional role PDMS. This is vital in a real world setting since the boiling process of frying may ultimately reduce the LOPs suppression activity of PDMS.

Terpenoids and Polyphenols as Natural Antioxidant Agents in Food Preservation

Synthetic antioxidant food additives, such as BHA, BHT and TBHQ, are going through a difficult time, since these products generate a negative perception in consumers. This has generated an increased pressure on food manufacturers to search for safer natural alternatives like phytochemicals (such as polyphenols, including flavonoids, and essential oils rich in terpenoids, including carotenoids). These plant bioactive compounds have antioxidant activities widely proven in in vitro tests and in diverse food matrices (meat, fish, oil and vegetables). As tons of food are wasted every year due to aesthetic reasons (lipid oxidation) and premature damage caused by inappropriate packaging, there is an urgent need for natural antioxidants capable of replacing the synthetic ones to meet consumer demands. This review summarizes industrially interesting antioxidant bioactivities associated with terpenoids and polyphenols with respect to the prevention of lipid oxidation in high fat containing foods, such as meat (rich in saturated fat), fish (rich in polyunsaturated fat), oil and vegetable products, while avoiding the generation of rancid flavors and negative visual deterioration (such as color changes due to oxidized lipids). Terpenoids (like monoterpenes and carotenoids) and polyphenols (like quercetin and other flavonoids) are important phytochemicals with a broad range of antioxidant effects. These phytochemicals are widely distributed in fruits and vegetables, including agricultural waste, and are remarkably useful in food preservation, as they show bioactivity as plant antioxidants, able to scavenge reactive oxygen and nitrogen species, such as superoxide, hydroxyl or peroxyl radicals in meat and other products, contributing to the prevention of lipid oxidation processes in food matrices.

Tea polyphenols (TP): a promising natural additive for the manufacture of multifunctional active food packaging films

As a bioactive extract from tea leaves, tea polyphenols (TP) are safe and natural. Its excellent antioxidant and antibacterial properties are increasingly regarded as a good additive for improving degradable food packaging film properties. This article comprehensively reviewed the functional properties of active films containing TP developed recently. The effects of TP addition to enhancing active food packaging films' performance, including thickness, water sensitivity, barrier properties, color, mechanical properties, antioxidant, antibacterial, and intelligent discoloration properties, were discussed. Besides, the practical applications in food preservation of active films containing TP are also discussed. This work concluded that the addition of TP could impart antioxidant and antibacterial properties to active packaging films and act as a crosslinking agent to improve other physical and chemical properties of the film, such as mechanical and barrier properties. However, the effect of TP on specific properties of the active packaging film is complex, and the appropriate TP concentration needs to be selected according to the type of film matrix and the interaction between the components. Notably, the addition of TP improved the efficiency of the active packaging film in food preservation applications, which accelerates the process of replacing the traditional plastic-based food packaging with active packaging film.

Improving the oxidative stability of virgin olive oil using microformulated vitamin-C

This study aims to improve the oxidative stability of olive oil using microformulated vitamin-C (Vit-C). The microemulsion containing 10,000 µg/ml Vit-C with a droplet size of 1,000 ± 68 nm was first prepared. Free radical scavenging of olive oil and olive oil containing blank microemulsion, different amounts of formulated Vit-C (100-500 µg/ml), and TBHQ (100 and 200 µg/ml as a standard antioxidant) was around 90% during 21 days of incubation at 60°C. The oxidative stability of the mentioned samples during incubation was investigated using the rancimat test, and their quality criteria analysis was studied by peroxide and the acid values. Results showed that the sample's acid value containing 500 µg/ml of Vit-C did not show significant differences (p < .05) with samples containing TBHQ. However, samples containing TBHQ's peroxide value were significant (p < .05) lower than samples containing 500 µg/ml of Vit-C. Furthermore, the induction time of samples containing 500 µg/ml of Vit-C was significantly (p < .05) higher than other treatments during incubation. Thus, the prepared microemulsion could be used as a natural antioxidant in the oil industry instead of harmful synthetic TBHQ.

The challenge of exploiting polyphenols from olive leaves: addition to foods to improve their shelf-life and nutritional value

Olive leaves represent a waste from the olive oil industry which can be reused as source of polyphenols. The most representative phenolic compound of olive leaves is the secoiridoid oleuropein, followed by verbascoside, apigenin-7-O-glucoside, luteolin-7-O-glucoside, and simple phenols. The attention towards these compounds derives above all from the large number of studies demonstrating their beneficial effect on health, in fact olive leaves have been widely used in folk medicine in the Mediterranean regions. Moreover, the growing demand from consumers to replace the synthetic antioxidants, led researchers to conduct studies on the addition of plant bioactives in foods to improve their shelf-life and/or to obtain functional products. The current study overviews the findings on the addition of polyphenol-rich olive leaf extract (OLE) to foods. In particular, the effect of OLE addition on the antioxidant, microbiological and nutritional properties of different foods is examined. Most studies have highlighted the antioxidant effect of OLE in different food matrices, such as oils, meat, baked goods, vegetables, and dairy products. Furthermore, the antimicrobial activity of OLE has been observed in meat and vegetable foods, highlighting the potential of OLE as a replacer of synthetic preservatives. Finally, several authors studied the effect of OLE addition with the aim of improving the nutritional properties of vegetable products, tea, milk, meat and biscuits. Advantages and drawbacks of the different use of OLE were reported and discussed. © 2020 Society of Chemical Industry.

Recent advancements in encapsulation of bioactive compounds as a promising technique for meat preservation

Encapsulation is currently considered as one the most valuable methods for preserving aromatic compounds or hiding odors, enhancing their thermal and oxidative stability, and expanding their food applications. Indeed, this current article was aimed to provide an overview regarding the encapsulation of plant bioactive compounds and the spray-drying and extrusion processes with a focused discussion regarding the encountered challenges for meat and meat product preservation. Furthermore, different ranges of carbohydrates as wall materials (carriers) besides the process conditions' effects on the encapsulation effectiveness and the particle size of the encapsulated bioactive compounds have been discussed. The encapsulation of these compounds ameliorates the quality of the stored meat products by further delaying in microflora growth and lipid/protein oxidation. Therefore, the innovative technologies for plant active compounds encapsulation offer a prospective alternative for natural preservation development in the meat industry.

Gluten-Free Breadsticks Fortified with Phenolic-Rich Extracts from Olive Leaves and Olive Mill Wastewater

Nowadays, food processing by-products, which have long raised serious environmental concerns, are recognized to be a cheap source of valuable compounds. In the present study, incorporation of phenolic-rich extracts (500 and 1000 mg kg⁻¹) from olive leaves (OL) and olive mill wastewater (OMW) into conventional gluten-free formulations has been exploited as a potential strategy for developing nutritious and healthy breadsticks with extended shelf-life. To this end, moisture, water activity (a_w), visual and textural properties, the composition of biologically active compounds (soluble, insoluble, and bio-accessible polyphenols), antioxidant activity, oxidation stability, and consumer preference of the resulting breadsticks were investigated. Fortified breadsticks had higher moisture and a_w, lower hardness, and similar color in comparison to the control, especially in the case of OL extract supplementation. All enriched formulations significantly affected the phenolic composition, as evidenced by the decrease in insoluble/soluble polyphenols ratio (from 7 in the control up to 3.1 and 4.5 in OL and OMW, respectively), and a concomitant increase in polyphenol bio-accessibility (OL: 14.5–23% and OMW: 10.4–15% rise) and antioxidant activity (OL: 20–36% and OMW: 11–16% rise). Moreover, a significant shelf-life extension was observed in all fortified breadsticks (especially in case of OMW supplementation). Sensory evaluation evidenced that 61% of the assessors showed a marked, but not significant, tendency to consider the sample supplemented with high levels of OL as a more palatable choice.

The application of polyphenols in food preservation

Polyphenols are a kind of complex secondary metabolites in nature, widely exist in the flowers, bark, roots, stems, leaves, and fruits of plants. Numerous studies have shown that plant-derived polyphenols have a variety of bioactivities due to their unique chemical structure, such as antioxidant, antimicrobial, and prevention of chronic diseases, cardiovascular disease, cancer, osteoporosis, and neurodegeneration. With the gradual rise of natural product development, plant polyphenols have gradually become one of the research hotspots in the field of food science due to their wide distribution in the plants, and the diversity of physiological functions. Owing to the extraordinary antioxidant and antibacterial activity of polyphenols, plant-derived polyphenols offer an alternative to chemical additives used in the food industry, such as oil, seafood, meat, beverages, and food package materials. Based on this, this chapter provides an overview of the potential antioxidant and antibacterial mechanisms of plant polyphenols and their application in food preservation, it would be providing a reference for the future development of polyphenols in the food industry.

Novel Processes for the Extraction of Phenolic Compounds from Olive Pomace and Their Protection by Encapsulation

Olive pomace, the solid by-product derived from olive oil production consists of a high concentration of bioactive compounds with antioxidant activity, such as phenolic compounds, and their recovery by applying innovative techniques is a great opportunity and challenge for the olive oil industry. This study aimed to point out a new approach for the integrated valorization of olive pomace by extracting the phenolic compounds and protecting them by encapsulation or incorporation in nanoemulsions. Innovative assisted extraction methods were evaluated such as microwave (MAE), homogenization (HAE), ultrasound (UAE), and high hydrostatic pressure (HHPAE) using various solvent systems including ethanol, methanol, and natural deep eutectic solvents (NADESs). The best extraction efficiency of phenolic compounds was achieved by using NADES as extraction solvent and in particular the mixture choline chloride-caffeic acid (CCA) and choline chloride-lactic acid (CLA); by HAE at 60 °C/12,000 rpm and UAE at 60 °C, the total phenolic content (TPC) of extracts was 34.08 mg gallic acid (GA)/g dw and 20.14 mg GA/g dw for CCA, and by MAE at 60 °C and HHPAE at 600 MPa/10 min, the TPC was 29.57 mg GA/g dw and 25.96 mg GA/g dw for CLA. HAE proved to be the best method for the extraction of phenolic compounds from olive pomace. Microencapsulation and nanoemulsion formulations were also reviewed for the protection of the phenolic compounds extracted from olive pomace. Both encapsulation techniques exhibited satisfactory results in terms of encapsulation stability. Thus, they can be proposed as an excellent technique to incorporate phenolic compounds into food products in order to enhance both their antioxidative stability and nutritional value.

Protective Action of Jania rubens Nanoencapsulated Algal Extract in Controlling Vegetable Oils' Rancidity

The development of natural antioxidants that can mitigate oil oxidation is on the rise. Several antioxidants have been developed from natural terrestrial plants, with less emphasis on marine algae. Rancidity is a major degradative reaction limiting the shelf-life and deteriorating the quality of vegetable oils. The goal of this study was to evaluate the ability of the Jania rubens' (J. rubens) seaweed extract encapsulated by chitosan/tripolyphosphate in retarding lipids' oxidation in vegetable oils. To improve the J. rubens efficacy, the extract was nanoencapsulated using the ionic gelation method. A Box-Behnken design was applied for the optimization of the formulation variables (chitosan/tripolyphosphate amounts, homogenization time, and homogenization speed). The optimum nanoformulation was characterized by transmission electron microscopy. It had a particle size of 161 nm, zeta potential of 31.2 mV, polydispersity index of 0.211, and entrapment efficiency of 99.7%. The ability of the optimum formula to extend the shelf-life of vegetable oils was based on peroxide value and thiobarbituric acid assays. In addition, headspace solid-phase microextraction was applied to detect the oils' volatiles as secondary markers of rancidity. The results revealed that the nanoencapsulated algal extract considerably reduced the rate of oils' oxidation and that its activity was comparable to that of a widely used synthetic antioxidant.

The aplication of Pistacia khinjuk extract nanoemulsion in a biopolymeric coating to improve the shelf life extension of sunflower oil

In the present study, a hydroalcoholic extract of P. khinjuk was obtained by sonication method at 60°C for 50 min. The measurement revealed that the total phenolic content of the extract was 46.0 mg/g. The results showed that the extract has an antioxidant activity of 73.5% and 8.3 (µmol TE/g DW) in DPPH radical scavenging method and FRAP assay, respectively. Also, Balango (Lallemantia royleana) and Fenugreek (Trigonella foenum-graecum) seed gum and their composition (1:1) were used to prepare the nanoemulsion with P. khinjuk extract. The droplet mean size of nanoemulsions was ranged from 310.34 to 354.19 nm. The highest encapsulation efficiency was observed in Balango nanoemulsion. P. khinjuk extract nanoemulsion coating with Balango and TBHQ was added to sunflower oil at 200 and 100 ppm, respectively. During 24-day storage at 60°C, samples were investigated for peroxide, acid, and p-anisidine values at 4-day intervals. The results showed that oils containing nanoemulsion had the highest stability during storage. However, in all samples peroxide, acid and p-anisidine values increased but the rate of oxidation in samples containing both synthetic and natural antioxidants was slower than the control sample.

Nanoencapsulation of unsaturated omega-3 fatty acids as protection against oxidation: A systematic review and data-mining

The chemical structure of unsaturated fatty acids makes them highly prone to oxidation, which decreases their nutritional properties. Nanocarriers have the ability to protect unstable nutraceuticals and take them to their specific targets. Thus, the aim is to determine the effectiveness of nanoencapsulation of omega-3 unsaturated fatty acids as protection against oxidation, as well as to apply data-mining approach to identify nanoencapsulation profiles. Three databases were used to search for studies focused on comparing omega-3 encapsulation to the active compound in its raw form. Studies without oxidation test or no use omega 3-rich oil as active ingredient in nanoformulations were excluded. Twenty-three studies were included in the systematic review. The qualitative analysis indicated that the main evaluated parameters were encapsulation efficiency (%), physical-chemical parameters and oxidation (analyzed at different storage temperatures), oil type, and whether the formulation was added to food. With regard to quantitative analysis, studies that did not perform oxidation tests focused on comparing free oil to the encapsulated one were excluded. Data-mining indicated that encapsulation efficiency and particle size were the main characteristic defining nanocarrier's effectiveness in protecting the oil against oxidation. Nevertheless, it is important to note the main characteristics associated with oil protection in nanocarriers.

Nanoemulsions for health, food, and cosmetics: a review

Nanoemulsions are gaining importance in healthcare and cosmetics sectors as a result of the unique properties of nanosized droplets, such as high surface area. Here we review nanotechnology and nanoemulsions with focus on emulsifiers and nanoemulsifiers, and applications for drugs and vaccines delivery, cancer therapy, inflammation treatment, cosmetics, perfumes, polymers, and food. We discuss nanoemulsion safety and properties, e.g., stability, emulsification, solubility, molecular number and arrangements, ionic strength, pH and temperature.

Microbiological and Antioxidant Activity of Phenolic Compounds in Olive Leaf Extract

According to many reports, phenolic compounds isolated from olive leaves have very good biological activities, especially antimicrobial. Presently, the resistance of microorganisms to antibiotics is greater than ever. Therefore, there are numerous recent papers about alternative solutions for inhibiting their influence on human health. Olive leaf is studied as an important source of antimicrobials with low cost and used in medicine. Numerous publications on involving green technologies for isolation of active compounds from olive leaves have appeared over the past few decades. The present review reports on current knowledge of the most isolated phenolic compounds from olive leaf extract as well as methods for their isolation and characterization. This paper uses recent research findings with a wide range of study models to describe the antimicrobial potential of phenolic compounds. It also describes the vast range of information about methods for determination of antimicrobial potential focusing on effects on different microbes. Additionally, it serves to highlight the role of olive leaf extract as an antioxidants and presents methods for determination of antioxidant potential. Furthermore, it provides an overview of presence of enzymes. The significance of olive leaves as industrial and agricultural waste is emphasized by means of explaining their availability, therapeutic and nutritional effects, and research conducted on this field.

Antioxidant Properties of Soybean Oil Supplemented with Ginger and Turmeric Powders

Soybean oil has been supplemented with 10% (w/w) of ginger and turmeric powders derived from commercial products (GC—commercial ginger and TC—commercial turmeric), freeze-dried rhizomes (freeze-dried ginger (GR) and freeze-dried turmeric rhizome—TR) and peels (freeze-dried ginger peel (GP) and freeze-dried turmeric peel—TP) for developing a functional seasoning with great lipid stability for human consumption. The exhausted ginger and turmeric powders were also recovered and recycled two times to promote a more sustainable process. The antioxidant activity and oxidative stability of oil samples were evaluated respectively by spectrophotometric and Rancimat methods. Folin–Ciocalteu assay and HPLC analysis were also performed to quantify total polyphenols, ginger-derived 6-gingerol and 6-shogaol, and turmeric-derived curcumin. Their antioxidant activity as well as oxidative stability, which non-linearly decreased over cycles because of a strongly reduced phenolic extractability, linearly increased with increasing phenolic yields. Hence, ginger and turmeric can be proposed as healthy spices containing bioactive compounds to control lipid oxidation and improve oil stability. Moreover, the valorization of peels as eco-friendly source of natural antioxidants is a valid strategy for providing added-value to these agro-food wastes.

Spectroscopic, molecular docking and molecular dynamic simulation studies on the complexes of β-lactoglobulin, safranal and oleuropein

Herbal bioactive compounds have captured pronounced attention considering their health-promoting effects as well as their functional properties. In this study, the binding mechanism between milk protein bovine β-lactoglobulin (β-LG), oleuropein (OLE) and safranal (SAF) found in olive leaf extract and saffron, respectively via spectroscopic and in silico studies. Fluorescence quenching information exhibited that interactions with both ligands were spontaneous and hydrophobic interactions were dominant. Also, the CD spectroscopy results demonstrated the increase in β-sheet structure and decrease in the α-helix content for both ligands. Size of β-LG-OLE complex was higher than β-LG-SAF due to the conformation and larger molecular size. Molecular docking and simulation studies revealed that SAF and OLE bind in the central calyx of β-LG and the surface of β-LG next to hydrophobic residues. Lastly, OLE formed a more stabilized complex compared to SAF based on the molecular dynamic simulation results.

Formulation and Preparation of Water-In-Oil-In-Water Emulsions Loaded with a Phenolic-Rich Inner Aqueous Phase by Application of High Energy Emulsification Methods

Currently, industry is requesting proven techniques that allow the use of encapsulated polyphenols, rather than free molecules, to improve their stability and bioavailability. Response surface methodology (RSM) was applied in this work to determine the optimal composition and operating conditions for preparation of water-in-oil-in-water (W/O/W) emulsions loaded with phenolic rich inner aqueous phase from olive mill wastewater. A rotor-stator mixer, an ultrasonic homogenizer and a microfluidizer processor were tested in this study as high-energy emulsification methods. Optimum results were obtained by means of microfluidizer with 148 MPa and seven cycles input levels yielding droplets of 105.3 ± 3.2 nm in average size and 0.233 ± 0.020 of polydispersity index. ζ-potential, chemical and physical stability of the optimal W/O/W emulsion were also evaluated after storage. No droplet size growth or changes in stability and ζ-potential were observed. Furthermore, a satisfactory level of phenolics retention (68.6%) and antioxidant activity (89.5%) after 35 days of storage at room temperature makes it suitable for application in the food industry.

Olive Tree Leaves—A Source of Valuable Active Compounds

The agricultural and processing activities of olive crops generate a substantial amount of food by-products, particularly olive leaves, which are mostly underexploited, representing a significant threat to the environment. Olive leaves are endowed with endogenous bioactive compounds. Their beneficial/health-promoting potential, together with environmental protection and circular economy, merit their exploitation to recover and reuse natural components that are potentially safer alternatives to synthetic counterparts. These biomass residues have great potential for extended industrial applications in food/dietary systems but have had limited commercial uses so far. In this regard, many researchers have endeavoured to determine a green/sustainable means to replace the conventional/inefficient methods currently used. This is not an easy task as a sustainable bio-processing approach entails careful designing to maximise the liberation of compounds with minimum use of (i) processing time, (ii) toxic solvent (iii) fossil fuel energy, and (iv) overall cost. Thus, it is necessary to device viable strategies to (i) optimise the extraction of valuable biomolecules from olive leaves and enable their conversion into high added-value products, and (ii) minimise generation of agro-industrial waste streams. This review provides an insight to the principal bioactive components naturally present in olive leaves, and an overview of the existing/proposed methods associated with their analysis, extraction, applications, and stability.

The influence of stirring time and frequency of impeller rotation on evaluation of drops dimensions and rheological properties of the multiple emulsion

The analysis of drops and rheological measurements of the emulsion produced were presented in the article. The influence of stirring time and rotation frequency on the drops size of the emulsion produced in the propeller of diameter D = 0.1 m and liquid height H = 0.5D equipped with four standard flat dividers was defined. The Smith turbine stirrer was used to stir the emulsion produced. The drop size was defined for three different propeller rotation frequencies, 500 rpm, 1000 rpm and 1500 rpm. The stirring time, after which the samples were collected, was accordingly 15 min and 45 min. To produce the emulsion, sunflower oil was used in the oil phase and distilled water in the water phase. There were 6 measurement series all together, and they were presented as the diameter size distribution. The mean arithmetic diameter da, median dm and the mean Sauter diameter d32 were determined. The rheological measurements of the produced emulsions were presented in graphics as a function τ = f(γ) and were described as Herschel–Bulkley and Bingham models presented in Table 3.

An Overview of Natural Extracts with Antioxidant Activity for the Improvement of the Oxidative Stability and Shelf Life of Edible Oils

Many plant materials, such as fruits and vegetables as well as herbs and spices, represent valuable sources of antioxidants. In recent years, wastes from agriculture and food industrial processes have been shown to be interesting sources for bioactive compound recovery, strongly contributing to the circular economy. Nowadays, because of their possible adverse effects on human health, there is a tendency to replace synthetic antioxidants with natural compounds. This review attempts to critically summarize the current evidence on plant bioactives, extracted from food or waste, added to unsaturated vegetable oils, in order to obtain high added-value products and to ameliorate their oxidative stability and shelf life. The goal of this review is to demonstrate the current status of the research on edible oils added with natural plant bioactives, highlighting new approaches in the field of health-promoting foods.

Introducing nano/microencapsulated bioactive ingredients for extending the shelf-life of food products

The shelf-life of foods is affected by several aspects, mainly chemical and microbial events, resulting in a considerable decline in consumer's acceptance. There is an increasing interest to substitute synthetic preservatives with the plant-based bioactive ingredients which are safe and natural. However, full implementation of this replacement is postponed by some challenges associated with bioactive ingredients, including their low chemical stability, off-flavor, low solubility, and short-term effectiveness. Encapsulation could overcome these limitations. The present review explains current trends in applying natural encapsulated ingredients for food preservation based on a classified description including essential oils, plant extracts, phenolics, carotenoids, etc. and their application for extending food shelf-life mostly dealing with antimicrobial, ant-browning and antioxidant properties. Encapsulation techniques, especially nanoencapsulation, is a promising strategy to overcome their limitations. Moreover, better results are obtained using a combination of proteins and polysaccharides as wall materials than single polymers. The encapsulation method and type of encapsulants highly influences the releasing mechanism and physicochemical properties of bioactive ingredients. These factors together with optimizing the conditions of encapsulation process leads to a cost-effective and well encapsulated ingredient which is more efficient than its free form in shelf-life improvement. It has been shown that the well-designed encapsulation systems, finally, boost the shelf-life-promoting functions of the bioactive ingredients, mostly due to enhancing their solubility, homogeneity in food matrices and contact surface with deteriorative agents, and providing their prolonged presence over food storage and processing via increasing the thermal and processing stability of bioactive compounds, as well as controlling their release on food surfaces, or/and within food packages. To this end and given the numerous wall and bioactive core substances available, further studies are needed to evaluate the efficiency of many encapsulated forms of both conventional and novel bioactive ingredients in food shelf-life extending since the interactions and anti-spoiling behaviors of the ingredients in various encapsulation systems and foodstuffs are highly variable that should be optimized and characterized before any industrial application.

Structure and stability of W1/O/W2 emulsions as influenced by WPC and NaCl in inner aqueous phase

Effect of WPC and NaCl in internal aqueous phase (W₁) of W₁/O/W₂ type double emulsions was studied. Pre-emulsion and final emulsion were prepared using microfluidizer and Ultra-Turrax high shear mixer, respectively. The emulsions prepared using salt exhibited uniform droplet size distribution and structural integrity. WPC at 6% and NaCl at 2 or 4% levels demonstrated better sedimentation stability (> 99%) and encapsulation stability (> 95%) during preparation and storage of double emulsions. Samples without added NaCl showed poor emulsion stability and structural integrity. Higher level of WPC i.e. 8% resulted in poor stability and encapsulation efficiency of double emulsions at all salt levels. Combined use of optimum levels of WPC and NaCl along with processing interventions resulted in stable double emulsions even after storage at room temperature for 10 days. This study highlights the fact that structural integrity of internal aqueous phase (W₁) depends upon presence of osmotic agent i.e. salt and stabilising proteins i.e. WPC.

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

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

Ultrasound-assisted development of stable grapefruit peel polyphenolic nano-emulsion: Optimization and application in improving oxidative stability of mustard oil

Grapefruit (Citrus paradisi) peel (GP) is rich in flavonoids and phenolics which have several proven pharmacological effects. However, their chemical instability towards oxygen, light and heat limits its applications in food industries. In the present study, we evaluated the feasibility of fabricating grapefruit-peel-phenolic (GPP) nano-emulsion in mustard oil using ultrasonication. Response surface methodology (RSM) optimization revealed that sonication time of 9.5 min at 30% amplitude and 0.52% Span-80 produced the stable GPP nano-emulsion with a droplet size of 29.73 ± 1.62 nm. Results indicate that both ultrasonication and Span-80 can assist the fabrication of a stabilized nano-emulsion. This study is one of its kind where nano-encapsulation of GPP into W/O emulsion was done to stabilize the active compound inside mustard oil and then the nano-emulsion was used to extend oxidative stability of mustard oil. Findings provide a basic guideline to formulate stable nano-emulsions for their use in active food packaging, oils, and pharmaceuticals.

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.