Improved Emulsion Stability Research Articles

Optimization of Pectin Extraction from Sweet Potato Peels Using Citric Acid and its Emulsifying Properties.

Pectin is a natural polysaccharide that has been used widely as a stabilizer in food emulsion system. This study aimed to optimize the yield of pectin extracted from sweet potato residue and investigate its emulsifying properties. Response surface methodology (RSM) has been utilized to investigate the pectin extracted from sweet potato peels using citric acid as the extracting solvent. Investigation of the effect of different extraction conditions namely temperature (°C), time (min) and solution pH on pectin yield (%) were conducted. A Box-Benhken design with three levels of variation was used to optimize the extraction conditions. The optimal conditions determined were temperature 76°C, time 64 min and pH 1.2 with 65.2% yield of pectin. The degree of esterification (DE) of the sweet potato pectin was determined using Fourier Transform Infrared (FTIR) Spectroscopy. The pectin is high-methoxyl pectin with DE of 58.5%. Emulsifying properties of sweet potato pectin were investigated by measuring the zeta-potential, particle size and creaming index with addition of 0.4 and 1.0 wt % pectin to the emulsion. Extraction using citric acid could improve the pectin yield. Improved emulsion stability was observed with the addition of the sweet potato pectin.

Dragon fruit (Hylocereus undatus) peel as antioxidant dietary fibre on quality and lipid oxidation of chicken nuggets.

In this study, the efficacy of dragon fruit peel (DFP) powderas antioxidant dietaryfibre(ADF), at two different concentrations (T1-1.5% and T2-3.0%), on quality improvement and susceptibility to lipidoxidationof chicken nuggets during 20days of refrigerated storage was assessed. DFP, rich in dietary fibre (56.91%) with higher insoluble dietary fibre, phenolics (36-39mgGAE/100g) content and possessing good radical scavenging activity as well as reducing power, contained 10.36% protein, 4.48% fat and 2.34% ash. HPLC analysis revealed presence of high concentrations of gallic and ferulic acid, among the phenolics. Incorporation of DFP in nuggets although decreased the pH but improved emulsion stability as well as cooking yield and had higher protein, ash and lower fat content. Further, the treated nuggets had significantly (p < 0.05) higher dietary fibre and total phenolics content than control. Incorporation of DFP decreased the hardness, gumminess and chewiness and improved (p < 0.05) the products' redness values. Sensory evaluation of the products revealed significant improvement in the appearance score and non-significant (p > 0.05) increase in the scores of other attributes compared to control samples. DFP significantly decreased lipid peroxidation, odour scores and microbial load in chicken nuggets during 20days of storage period. From the study, it could be deduced that DFP rich in bioactive components had positive influence on the nutritional quality of chicken nuggets and could also be used as ADF in muscle food without affecting the quality and acceptability of products.

The influence of thermal hydrolysis process on emulsifying properties of potato protein isolate.

The article considers the influence of the thermal hydrolysis process on emulsifying properties and viscosity of potato protein isolates. During the study, there was demonstrated a significant improvement in emulsifying properties of the protein isolates as a result of denaturation. Thermal hydrolysis process includes high temperature and pressure. The improvement in emulsion stability maintained in some variants up to a week has been observed. Significant correlations were found between emulsification activity and emulsion stability after 1week (p > 0.05). The rheological measurement showed an increase in viscosity after HPP. As the proposed method of the protein isolate modification does not affect the chemical composition of the protein solution, but only its molecular structure, it enables to increase the emulsifying properties in a simple and cost-effective way.

Alpha-cyclodextrin as a new functional ingredient in low-fat chicken frankfurter

ABSTRACT 1. The current consumer preference for healthier meat products is associated with less additives in manufacturing (so-called ‘clean-label’) or the addition of non-meat ingredients with functional properties, recognised as improving specific technological properties in meat products. 2. This study evaluated the effect of the addition of alpha-cyclodextrin and wheat fibre to low-fat chicken frankfurters containing 35% mechanically deboned chicken meat on the technological and sensorial properties during refrigerated storage. 3. The results showed that the addition of dietary fibres (alpha-cyclodextrin and wheat fibre) in low-fat chicken frankfurters improved emulsion stability, hardness, chewiness and reduced cohesiveness. 4. Alpha-cyclodextrin helped the retention of fat globules in the microstructure and affected colour in the sensorial evaluation. 5. The use of alpha-cyclodextrin, in combination with wheat fibre, as a new ingredient to substitute fat in emulsified meat products containing mechanically deboned chicken, improved emulsion stability and texture. 6. Alpha-cyclodextrin and wheat fibre were effective in contributing to fat reduction without affecting the sensory properties of the product.

Surface and Interfacial Interactions in Dodecane/Brine Pickering Emulsions Stabilized by the Combination of Cellulose Nanocrystals and Emulsifiers.

Interfacial properties of cellulose nanocrystals (CNC) and surfactants were studied in high ionic strength (I) brines and correlated to the stability of dodecane/brine Pickering emulsions. Bis-(2-hydroxyethyl) cocoalkylamine (CAA), dodecyltrimethylammonium bromide (DTAB), and octyl-β-d-glucopyranoside (OGP) were adsorbed onto CNC in American Petroleum Institute (API) brine (I = 1.9 M) and synthetic seawater (SSW), with I = 0.65 M. Raman spectroscopy indicated that hydroxyl groups on the CNC surface interact with all three surfactants in high ionic strength media. Ionic interactions still play a role at the very large ionic strengths studied herein. Despite all surfactants adsorbing onto CNC, only the surface tension of CAA solutions in both brines was increased by the addition of 0.5 wt % CNC. The effect was much more prominent in API than in SSW. Contact angle measurements indicated that CAA increased the wettability of CNC by both brines in dodecane; DTAB, on the other hand, decreased wettability. Emulsion stability studies revealed that ionic strength, wettability, adsorption energy, and oil content strongly affect emulsion stability, more so than surfactant adsorption. In API, CNC aggregates alone stabilized the emulsions better compared to samples with additional emulsifiers; the same was true in SSW for oil contents below 50% v/v. For oil contents above 50% v/v in SSW, CAA was either detrimental or failed to improve emulsion stability. On the other hand, DTAB increased the stability of dodecane in SSW emulsions. Emulsions stable for over 21 months were prepared with oil contents of 75% v/v. The adsorption of CAA onto CNC limits the migration of both CNC and CAA to the dodecane/brine interface, while DTAB adsorption has the opposite effect.

Physico-chemical and functional properties of dried male date palm flowers

The physico-chemical, microstructure, thermal and functional properties of Deglet Nour male date palm flowers (MDPF) of Phoenix dactylifera L. were studied. The main objective was to add value to this discarded by-product as a functional raw material and assess its suitability to be incorporated into foods. The pollen-free flowers were dried at 40 °C. Then, a milling step was used to obtain the powdered MDPF. The results showed high amounts not only of dietary fibres (68%), especially insoluble fibre (64%), but also of proteins (14.8%), which confirmed the nutritional value of the MDPF and its possible use in dietetic products. The physical properties showed that dried MDPF were safe from deterioration, had a light colour suitable for incorporation, had an amorphous structure helpful for preservation and were thermally stable suggesting that MDPF could be a natural stabilizer. Moreover, MDPF showed interesting functional properties expressed by relatively high swelling values, and water and oil holding capacities (6.3 ml/g dry sample, 4.95 g water/g dry sample and 4.42 g oil/g dry sample, respectively), which may be helpful in foods to minimize some technical problems (e.g., improving emulsion stability in fatty products and avoiding syneresis).

Fatty acid composition and quality properties of chicken sausage formulated with pre-emulsified perilla-canola oil as an animal fat replacer

The potential use of an oil in water (o/w) emulsion made from perilla and canola oil in chicken sausage as an animal fat replacer was assessed. The (o/w) emulsion was made from 50% (wt/wt) perilla-canola oil mixture in a 30:70 ratio, 3.20% (wt/wt) polyglycerol polyricinoleate, 4.48% (wt/wt) soy protein isolate, 14% (wt/wt) inulin, and 28.32% (wt/wt) water. The sausages were manufactured with 60% (wt/wt) ground chicken breast, 20% (wt/wt) fat (beef tallow as a control), and 20% (wt/wt) ice water. Full replacement of animal fat with a perilla-canola oil (o/w) emulsion reduced the fat content and estimated calories but increased the moisture, protein, ash, and carbohydrate content. The proportion of α-linolenic acid (C18:3n3) was increased when animal fat was replaced with either a perilla-canola oil mixture or pre-emulsified perilla-canola oil, resulting in a lower n6 to n3 polyunsaturated fatty acid ratio than the control. The perilla-canola oil (o/w) emulsion improved emulsion stability and minimized cooking loss during sausage manufacturing. Higher L* value (lightness) and whiteness were observed in the sausages formulated with the perilla-canola oil mixture, followed by the pre-emulsified perilla-canola oil and the control. The perilla-canola oil (o/w) emulsion also increased the hardness but maintained an acceptable appearance, flavor, and overall impression similar to the control. The shelf life could be extended by vacuum packing and storing the cooked sausages formulated with a perilla-canola oil (o/w) emulsion for 30 D at 2 ± 1°C. Pre-emulsified perilla-canola oil could be used to replace animal fat in reduced-fat chicken sausage manufacture.

Improved emulsion stability and resveratrol encapsulation by whey protein/gum arabic interaction at oil-water interface

This work studied the effects of different concentrations of gum arabic (GA) on the interfacial adsorption kinetics of whey protein (WP) at the oil–water interface, the possibility of emulsion stabilized by WP/GA mixtures, and use of such emulsions as resveratrol delivery systems. Dynamic interface pressure measurements indicated that the change of GA concentration significantly affected the diffusion, penetration and rearrangement of WP at the oil–water interface, while measurements of hydrodynamic diameter and ζ-potential indicated electrostatic and hydrophobic interactions between WP and GA. The rheological measurements of the emulsions supported the above observations and indicated that different GA concentrations affected the viscoelastic properties of the emulsion. Adding resveratrol into oil influenced the adsorption of WP at the oil–water interface, thus affecting the emulsion stability and the encapsulation efficiency of resveratrol. The emulsions stabilized by WP and WP/GA mixtures have encapsulation efficiencies of >50% for resveratrol, while emulsions showed the best stability at a GA concentration of 0.2%. These results indicate that GA could effectively improve the emulsifying capacity of WP, while the emulsions prepared by WP/GA mixtures have the potential to serve as carriers for bioactive components.

Partial and total replacement of meat by plant-based proteins in chicken sausage: evaluation of mechanical, physico-chemical and sensory characteristics.

The processed meats are classified in the first category of carcinogenic compounds due to its numerous health issues. For this reason, there is a growing interest to utilize healthy ingredients for formulation of meat-based products. The objective of this study was to replace completely and partially meat by plant proteins in sausage formulation and compare the characteristics of these novel formulae with full meat sample. The results showed that the plant proteins minimized the cooking loss and shrinkage and improved emulsion stability by creating a strong structural network in cooked emulsion. In contrast, the full meat samples had better strength/elasticity in terms of folding score (4.67 out of 5) and gel strength (2553.68gmm) when compared to meat-reduced and meat-free samples. The sensory assessment showed that replacement of chicken meat by plant proteins was highly acceptable in terms of texture, odor, color and overall acceptance. Overall, it is concluded that plant proteins can be regarded as promising ingredients to replace 80-100% meat in sausage.

Investigation into the properties of water-in-heavy oil emulsion and its role in enhanced oil recovery during water flooding

Abstract This paper described an investigation into the properties of water-in-heavy oil emulsion and its role in enhanced oil recovery (EOR). Effect of pH and salinity on emulsion stability, droplet size and distribution as well as rheological behavior were researched. Core flooding experiments were conducted to study the role of emulsion on EOR. Results indicated that stability of emulsions decreased as salinity increased. The presence of salt leads to a rise in droplet size and a drop in uniformity of distribution. Besides, emulsion formed at pH of 7 was characterized by the least stability, largest droplet size and unevenest droplet size distribution. An increase or decrease in pH both improved emulsion stability and reduced droplet size. Equally, rheological property of emulsion was greatly affected by salinity and pH. In relatively low shear rate region (

Viscosity reduction of acidic heavy oil through emulsification: effects of salinity and pH

In this research, sodium dodecyl sulfonate (SDS) was selected as emulsifying viscosity reducer through a great number of laboratory experiments and then the effects of salinity and pH on viscosity reduction effects were evaluated. The result showed that higher salinity would result in emulsion viscosity enhancement. Compared with neutral pH conditions (pH =7), both acidic and basic conditions would promote emulsion viscosity reduction. When pH >7, generated O/W emulsions were much more stable than all other emulsions. Detailed compositional characterization of petroleum acid through a high resolution mass spectrometer (FT-ICR MS) proved that carboxylic acid and phenols inside petroleum acid would react with OH- at basic conditions and produce some natural surfactants. Theses natural surfactants could work synergistically with SDS and further improve emulsion stability.

Molecular characterization of interacting complexes and conjugates induced by the dry-state heating of β-lactoglobulin and sugar beet pectin

To gain an understanding of the improved emulsion stability, exhibited by the Maillard-type reaction products consisted of whey protein isolate (WPI) and sugar beet pectin (SBP), we investigated the molecular properties of interacting complexes and conjugates formed between β-lactoglobulin (β-LG), the main protein of whey, and SBP. The reaction was carried out at varying mass ratios, β-LG:SBP = 1:0, 5:1, 3:1, 2:1, 1:1, and 0:1 through dry heating (60 °C, 79% RH, 72 h). The physiochemical properties of the products from the reaction were characterized by an online multi-detection (UV, dRI, MALLS, and DPV) HPSEC system. The results showed that although the molecular weight distribution and the shape of the SBP in each fraction was significantly transformed by heating alone, the overall apparent average weight-average molar mass ([Mw]av) and average intrinsic viscosity ([ηw]av) were not affected. Detailed analyses revealed about 29, 34, 44 and 56% of the total β-LG participated in the reactions and interactions with SBP for the mixture of 5:1, 3:1, 2:1, and 1:1 respectively. Furthermore, it was demonstrated that β-LG tends to interact with the group of SBP molecules with higher average weight-average molar mass [Mw] (∼800 kDa) through local electrostatic and hydrophobic interactions. Combination of complexes and conjugates was formed between β-LG and intermediate sized SBP (∼125 kDa), and the shapes of these two classes of SBP molecules were maintained, i.e., a mixture of compact spheres, random coils, and rigid rods. The conjugates were developed by the chemical reactions between β-LG and the group of SBP with the lowest [Mw] (∼100 kDa), leading to the products with altered molecular structures and increased chemical bond stiffness compared to that of SBP.

Investigation of the simultaneous chemicals influences to promote oil-in-water emulsions stability during enhanced oil recovery applications

Emulsion application in Enhanced Oil Recovery (EOR) processes is a common and practical subject in petroleum industry. Considering the chemical usage limitations, quantitative understanding of the ability of chemicals to improve other chemical performance is very important. In the present article, the coincident impacts of nanoparticles, salts and surfactants on interfacial tension reduction as well as zeta potential for determining the best emulsion stability have been examined. Resultant findings have shown that cobalt oxide nanoparticle and aluminum ions lead to an improvement in emulsion stability than each individually. Resulted emulsion stability indexes for cobalt oxide nanoparticles and aluminum ions are 0.48 and 0.49 at 25 °C and 0.54 and 0.66 at 50 °C, respectively. Nonetheless, their simultaneous presence, i.e., dispersion of cobalt oxide optimum weight percent in crude oil and dissolving of optimum aluminum ions concentration in water, change the stability indexes to 0.64 and 0.75 at temperatures of 25 °C and 50 °C, respectively. Presence of dispersed silica nanoparticles with low weight percent resulted in stability indexes of 0.49 and 0.43 at temperatures of 25 °C and 50 °C, respectively, but at high concentration because of repulsive forces against the asphaltene molecules, emulsion stability drops eventually with indexes of 0.35 and 0.26 at temperatures of 25 °C and 50 °C, respectively. While presence of cationic surfactant in the phase that silica nanoparticle is dispersed in, rises emulsion stability and viscosity. In all cases, along with emulsion stability increasing, quantities of zeta potential became more negative. But results of silica nanoparticle show that descending negative zeta potential trend of media does not lead to stability necessarily. This paper, quantitatively demonstrated that the effect of chemical co-existence by stimulating the polar molecules of crude oil caused a significant difference in emulsion stability than using the chemicals individually.

Effect of emulsifier HLB and stabilizer addition on the physical stability of thyme essential oil emulsions

ABSTRACTThe objective of this work was to formulate and to further improve the stability of emulsions based on thyme essential oil. Several nonionic surfactants of different nature and with different hydrophilic−lipophilic balance (HLB) values were investigated. The surfactant with optimal HLB found for the thyme essential oil was Appyclean 6548 (HLB: 9-9.5). Afterwards, stabilizing biopolymers were added in order to improve emulsion stability. Properties of emulsions were evaluated in terms of droplet size and physical stability. Thyme essential oil/W emulsions formulated with a new biodegradable emulsifier (alkyl polypentoside) and welan gum as stabilizer were obtained with high shelf-life.

Microencapsulation of docosahexaenoic acid (DHA) with four wall materials including pea protein-modified starch complex

Omega-3 fatty acids, specifically docosahexaenoic acid (DHA, 22 carbons and 6 double bonds) are fundamental compounds for a healthy diet. However, due to their unsaturated nature, omega fatty acid-rich oils are chemically unstable and susceptible to oxidative deterioration. The oxidation results in production of free radicals and unpleasant tastes, negatively impacting the shelf-life, sensory properties, and acceptability of food products. This study was conducted to examine the effect of wall materials on protection of DHA in canola oil against oxidation. A total of 4 wall materials including pea protein isolate (PPI), pea protein isolate - modified starch complex (PPI-MS), Tween 20, and SDS were used for microemulsion preparation with canola oil containing DHA. The freeze-dried powders were analyzed with respect to physicochemical characteristics, oxidative stability, and release properties. The results showed that the PPI-MS as a natural polymeric wall material exhibited similar or better encapsulation efficiency and acceptable level of peroxide value compared to the synthetic surfactants (Tween 20 and SDS). The utilization of protein-polysaccharide complexes enabled the incorporation of specific properties of each biopolymer to further improve emulsion stability for the production of capsules with improved oxidative stability.

Synergetic interfacial adsorption of protein and low-molecular-weight emulsifiers in aerated emulsions

Whipped creams (aerated emulsions) are a complex emulsion-foam system whose oil-stabilizing potential and aeration capacity are determined by the surface activity of proteins and small surfactants. In this study, the interaction between three low-molecular-weight (LMW) emulsifiers [sodium stearoyl lactylate (SSL), phospholipid (PL), and sucrose ester (SE)] with caseinate was investigated to elucidate the mechanism of formation and stability of whipped creams. Competitive adsorption, interfacial tension, droplet aggregation, viscosity, and morphological variations of the emulsions were examined, and aeration capacity, hardness, and microstructure of whipped creams were measured. The combination of surfactants (0.05–1.0% w/w) with caseinate (0.6% w/w) produced concerted effects on the stability of emulsions. Water-soluble surfactant (SE) adsorbed more strongly than oil-soluble surfactants (SSL and PL) onto oil droplets. The lesser protein adsorption in the SE emulsion enabled a strong foaming activity in the subsequent aeration. Protrusions of triacylglycerol crystals and aggregation of oil droplets into an interactive colloidal matrix with considerable hardness and viscosity were prominently observed in SE creams. On the other hand, shear thinning followed by thickening was observed when PL was added to form the caseinate-based emulsion while no foaming was produced, and SSL, known to form α-gel at the interface, produced no stable foam. The improved emulsion stability yet the propensity to coalesce induced by cooperative actions of casein molecules and hydrophilic surfactant played a crucial role in producing aerated emulsions.

Improved emulsion stability and modified nutrient release by structuring O/W emulsions using konjac glucomannan

Functional konjac glucomannan (KGM) was used to structure the water phase of O/W emulsions containing a lipophilic bioactive compound (β-carotene). KGM greatly increased the viscosity of the water phase and thus the viscosity of final emulsions. Results of Fourier-transform infrared spectroscopy (FT-IR) showed that there is no significant non-covalent interaction between KGM and whey proteins in the water phase. KGM significantly improved the creaming and pH stability of whey-protein-stabilized emulsions (p < 0.05), and significantly decreased the oiling-off of emulsions during freeze-thaw test. Emulsions with or without KGM all had good thermal stability at 80 °C. Microscopy observations indicated obvious aggregation of free proteins and oil droplets in gastric phase and an enzymatic-induced break-down of droplets, mainly in the intestinal phase of the simulated gastrointestinal tract (GIT) digestion. Emulsions with KGM-structured water phase showed a lower final release rate of encapsulated β-carotene than emulsion without KGM (p < 0.05), and the release rate decreased with the increasing KGM content. The findings of this study contribute to a better understanding of the influence of the water phase on the release of encapsulated compounds from emulsions, and make it possible to achieve controlled release of encapsulated compounds, and/or to deliver multiple health-beneficial nutrients at once by structuring emulsion-based carriers with functional natural biopolymers.

An alternative method to enhance w/o emulsion stability using modified dimer acid and its application in oil based drilling fluids.

This study presents an alternative method to enhance the emulsion stability of oil based drilling fluids (OBMs). Modified dimer acid (MDA) was synthesized with a molecular structure having two hydrophilic heads and two hydrophobic tails. Theoretically, the adsorption of MDA on an oil–water interface makes it possible to increase hydrogen bonding between water droplets and form three dimensional networks which benefit emulsion stability. The influence of MDA on the stability of base emulsions was studied by visual observation. Then the stabilization mechanism of MDA was analyzed from the micro and macro points of view by morphology study using a cryo-scanning electron microscope (cryo-SEM) and rheological measurements including viscosity vs. shear rates, zero-shear viscosity (η0), and creep and recovery tests. Experimental results showed that a substantial improvement in emulsion stability was visually observed when the MDA concentration was 2 g L−1. From cryo-SEM observation, a honeycomb structure was observed in the emulsion containing 2 g L−1 MDA, which can provide a physical barrier to restrain the movement of water droplets. In comparison with the rheological behaviors of the emulsion without MDA, a remarkably larger zero-shear viscosity, a solid-like behavior and a greater elasticity were observed when 2 g L−1 MDA was present. Finally, the application in OBMs shows that MDA can largely enhance electrical stability (ES) and reduce the filtration volume. The method proposed in the paper could be used to enhance the stability of w/o emulsions in a variety of fields.

A comparison of Canthaxanthine Pickering emulsions, stabilized with cellulose nanocrystals of different origins

Cellulosic nanocrystals from different origins were made to stabilize the canthaxanthin (CTX) in pickering emulsion. Nanocrystals were obtained by hydrochloric acid hydrolysis. Dynamic light scattering (DLS) demonstrated that the length of solid particles were in the range of 112nm–4000nm. AFM indicated the needle-like shape of the cotton cellulose nanocrystals (CCNs) and bacterial cellulose nanocrystals (BCNs) and also illustrated the thickness of the particles to be 6 and 7nm respectively. The crystallinity of both BCNs and CCNs was higher than the cellulose source they were isolated (CL: 75.4%, CCNs: 86.6; BC: 79.2%, BCNs: 88.5%). Effects of different factors such as temperature, pH and ionic concentration on stability were investigated. The results revealed that an increase in both temperature and pH was accompanied by an improvement in emulsion stability in all tested samples. However, increase in ionic concentration resulted in emulsions with less stability. In all the samples, CCN emulsions had better stability than the BCN emulsions, which was associated to smaller particle size and more coverage ability. Test of stability to light showed that CCN emulsions can preserve CTX better than BCN against the light.

Formulation and optimization of emulsions based on bitter fennel essential oil and EO/BO block copolymer surfactant

The influence of EO/BO block copolymer surfactant concentration in the range (1–5% (m/m)) and emulsification time on the emulsion stability and droplet size distribution of bitter fennel essential oil-in-water emulsions has been studied.Essential oils are promising material to be used for emulsion formulation with applications in cosmetics, food industry and agrochemicals. In the latter field these emulsions may be used as matrices for pesticides, where essential oils play the role of an eco-friendly solvent.A two-factor central composite design was conducted in order to optimize the emulsion formulation and processing. Emulsion stability has been studied as function of ageing time, by multiple light scattering (Turbiscan Lab-expert, Formulaction) and laser diffraction (Mastersizer X, Malvern). The surface response methodology allowed us to obtain a formulation comprising minimum droplet size and maximum stability by using a single step rotor/stator homogenization process.Creaming turned out to be the main destabilization mechanism. In order to improve emulsion stability the influence of high pressure homogenization (M110P, Microfluidics, MA, USA) and addition of a weighting agent (rosin gum) was studied. Although lower droplet sizes were obtained in both cases (D3,2 were in the range 0.30–0.35μm), emulsions were more unstable maybe due to Ostwald ripening phenomena.