The role of sodium dodecyl sulfate (SDS) micelles in inducing skin barrier perturbation in the presence of glycerol

The stratum corneum (SC) serves as the skin barrier between the body and the environment. When the skin is contacted with an aqueous solution of the surfactant sodium dodecyl sulfate (SDS), a well‐known model skin irritant, SDS penetrates into the skin and disrupts this barrier. It is well established, both in vitro and in vivo, that the SDS skin penetration is dose‐dependent, and that it increases with an increase in the total SDS concentration above the critical micelle concentration (CMC) of SDS. However, when we added the humectant glycerol at a concentration of 10 wt% to the aqueous SDS contacting solution, we observed, through in vitro quantitative skin radioactivity assays using ¹⁴C‐radiolabeled SDS, that the dose dependence in SDS skin penetration is almost completely eliminated. To rationalize this important observation, which may also be related to the well‐known beneficial effects of glycerol on skin barrier perturbation in vivo, we hypothesize that the addition of 10 wt% glycerol may hinder the ability of the SDS micelles to penetrate into the skin barrier through aqueous pores that exist in the SC. To test this hypothesis, we conducted mannitol skin permeability as well as average skin electrical resistivity measurements in vitro upon exposure of the skin to an aqueous SDS contacting solution and to an aqueous SDS + 10 wt% glycerol contacting solution in the context of a hindered‐transport aqueous porous pathway model of the SC. Our in vitro studies demonstrated that the addition of 10 wt% glycerol: (i) reduces the average aqueous pore radius resulting from exposure of the skin to the aqueous SDS contacting solution from 33 ± 5Å to 20 ± 5Å, such that a SDS micelle of radius 18.5 ± 1Å (as determined using dynamic light‐scattering measurements) experiences significant steric hindrance and cannot penetrate into the SC, and (ii) reduces the number density of aqueous pores in the SC by more than 50%, thereby further reducing the ability of the SDS micelles to penetrate into the SC and perturb the skin barrier.     

Encapsulation of functional lipophilic components in surfactant-based colloidal delivery systems: Vitamin E,vitamin D,and lemon oil

The fabrication and stability of surfactant-based colloidal delivery systems (microemulsions and emulsions) suitable for encapsulation of lipophilic active agents (vitamins and flavours) was investigated. An emulsion titration method was used to study the influence of surfactant type (Tween 20, 60 and 80) and oil type (Vitamin E, vitamin D₃ and lemon oil) on the incorporation of lipophilic components into surfactant micelles. Oil-in-water emulsions were formed and then different amounts were titrated into surfactant micelle solutions. The influence of surfactant-to-oil ratio (SOR) and oil type on the formation of colloidal dispersions was examined using dynamic light scattering and turbidity measurements. SOR, oil type, and surfactant type had a pronounced influence on the nature of the colloidal dispersions formed. Microemulsions could not be formed using vitamin D or E in 1% Tween solutions, due to the relatively large size of the lipophilic molecules relative to the hydrophobic interior of the surfactant micelles. On the other hand, microemulsions could be formed from lemon oil at relatively high SORs. There was not a major impact of non-ionic surfactant type (Tween 20, 60 or 80) on the formation and properties of the colloidal dispersions. However, Tween 20 micelles did appear to be able to solubilise less lemon oil than Tween 60 or 80 micelles, presumably due to their smaller dimensions. This study provides useful information for the rational design of food grade colloidal delivery systems for encapsulating flavour oils, oil-soluble vitamins, and other functional lipids for application in foods and beverages.     

In vitro and in vivo antifungal activity of a water-dilutable cassia oil microemulsion against Geotrichum citri-aurantii

BACKGROUND: Recently, food‐grade microemulsions have been of increasing interest to researchers and have shown great potential in industrial applications. In this study a food‐grade water‐dilutable microemulsion system with cassia oil as oil, ethanol as cosurfactant, Tween 20 as surfactant and water was developed and its antifungal activity in vitro and in vivo against Geotrichum citri‐aurantii was assessed. RESULTS: The phase diagram results confirmed the feasibility of forming a water‐dilutable microemulsion based on cassia oil. One microemulsion formulation, cassia oil/ethanol/Tween 20 = 1:3:6 (w/w/w), was selected with the capability to undergo full dilution with water. The average particle size was 6.3 nm. The in vitro antifungal experiments showed that the microemulsion inhibited fungal growth on solid medium and prevented arthroconidium germination in liquid medium and that cassia oil had stronger activity when encapsulated in the microemulsion. The in vivo antifungal experiments indicated that the water‐dilutable microemulsion was effective in preventing postharvest diseases of citrus fruits caused by G. citri‐aurantii. CONCLUSION: The results of this study suggest a promising utilisation of water‐dilutable microemulsions based on essential oils for the control of postharvest diseases. Copyright © 2012 Society of Chemical Industry     

Growth inhibition of Escherichia coli O157:H7 and Listeria monocytogenes by carvacrol and eugenol encapsulated in surfactant micelles

Growth inhibition of four strains of Escherichia coli O157:H7 (H1730, F4546, 932, and E0019) and Listeria monocytogenes (Scott A, 101, 108, and 310) by essential oil components (carvacrol and eugenol) solubilized in nonionic surfactant micelles (Surfynol 465 and 485W) was investigated. Concentrations of encapsulated essential oil components ranged from 0.02 to 1.25% depending on compound, surfactant type, and surfactant concentration (0.5 to 5%). Eugenol encapsulated in Surfynol 485W micelles was most efficient in inhibiting growth of the pathogens; 1% Surfynol 485W and 0.15% eugenol was sufficient to inhibit growth of all strains of E. coli O157:H7 and three of four strains of L. monocytogenes (Scott A, 310, and 108). The fourth strain, L. monocytogenes 101, was inhibited by 2.5% Surfynol and 0.225% eugenol. One percent Surfynol 485W in combination with 0.025% carvacrol was effective in inhibiting three of four strains of E. coli O157:H7. Strain H1730 was the most resistant strain, requiring 0.3% carvacrol and 5% surfactant for complete inhibition. Growth inhibition of L. monocytogenes by combinations of carvacrol and Surfynol 465 ranged between 0.15 and 0.35% and 1 and 3.75%, respectively. Generally, the antimicrobial activity of Surfynol 465 in combination with eugenol was higher than that for the combination with carvacrol. The potent activity was attributed to increased solubility of essential oil components in the aqueous phase due to the presence of surfactants and improved interactions of antimicrobials with microorganisms.     

Seed decontamination as an intervention step for eliminating Escherichia coli on salad vegetables and herbs

The efficacy of seed decontamination to enhance the safety of salad vegetables and herbs was evaluated. Seeds (celery, coriander, lettuce, spinach and watercress) were inoculated (at a level of 3–5 log cfu g⁻¹) with either Escherichia coli P36 or Listeria monocytogenes NCTC 7973 and decontaminated with ozone gas, acidified sodium chlorite (ASC) or quaternary ammonium salt preparation (QAS). None of the treatments applied were initially effective at inactivating E coli on lettuce or spinach seeds as the bacterium could be recovered on the subsequent seedlings. However, as the cultivation period progressed, E coli numbers on plants derived from decontaminated seeds declined to below the level of detection. Interestingly, E coli persisted on the surface of lettuce and spinach leaves from inoculated non‐treated seeds throughout the 42‐day cultivation period. E coli also persisted on coriander derived from inoculated non‐treated seeds although it was isolated sporadically on plants derived from QAS‐decontaminated seed. E coli numbers progressively declined on celery and watercress regardless of the seed decontamination treatment being applied. No L monocytogenes was recovered from any of the seedlings, possibly because of the growth‐suppressing effect of endogenous microflora. The results suggest that effective on‐farm controls, such as seed decontamination, should be considered in order to reduce the risk of pathogens associated with salad vegetables and herbs. Copyright © 2005 Society of Chemical Industry     

Solubilization Kinetics of Triacyl Glycerol and Hydrocarbon Emulsion Droplets in a Micellar Solution

Solubilization of oil molecules in surfactant micelles can have pronounced effects on the physicochemical properties of oil-in-water emulsions, e.g., reaction rates, distribution of nonpolar ingredients, emulsion stability and controlled flavor release. Static light-scattering was used to compare the solubilization kinetics of corn oil droplets with those of n-hexadecane droplets (ø= 0.02 wt%, d₃₂= 0.3 μm) in a micellar surfactant solution (2 wt% Tween 20). The n-hexadecane droplets were completely solubilized by the micelles within 5 days, but no change was observed in the corn oil emulsíon Possible reasons for the observed differences in solubilization kinetics were related to the molecular geometry and size of the oil molecules.     

In vitro and in vivo [corrected] activity of eugenol oil (Eugenia caryophylata) against four important postharvest apple pathogens

The activity of eugenol oil was evaluated in vitro and in vivo against four apple pathogens namely Phlyctema vagabunda, Penicillium expansum, Botrytis cinerea and Monilinia fructigena. The minimum inhibitory concentration (MIC) of eugenol incorporated in malt extract agar medium was found to be 2 mg ml(-1). Mycelial growth of the four test pathogens was completely inhibited when treated with 150 microl l(-1) of volatile eugenol whether at 4 or 20 degrees C. Conidia of P. vagabunda, P. expansum, M. fructigena and B. cinerea suspended for 2 min in eugenol solution at 2 mg ml(-1) heated to 50 degrees C germinated at rates of 19, 37, 38 and 39%, respectively. Three different eugenol formulations (Tween 80, ethoxylate and lecithin) were tested for their in vivo efficacy against the tested pathogens on apples. Ethoxylate- and Tween 80-eugenol formulations applied at room temperature were ineffective in reducing disease incidence. When heated to 50 degrees C, both formulations induced phytotoxicity on apple surface and caused cuticle damages as revealed by scanning electronic microscopic observations. A mixture of eugenol at 2 mg ml(-1) and soy lecithin at 50 mg ml(-1) suppressed the phytotoxic symptoms produced by eugenol on apples and reduced the disease incidence of P. expansum, P. vagabunda, B. cinerea and M. fructigena to less than 7, 6, 4 and 2% respectively after 6 months of storage at 2 degrees C. The application of heated lecithin-formulated eugenol could become a successful alternative to the traditional fungicides used in postharvest disease management of apple fruit.     

Texture,composition and anatomy of spinach leaves in relation to nitrogen fertilization

BACKGROUND: The postharvest quality and shelf life of spinach are greatly influenced by cultural practices. Reduced spinach shelf life is a common quandary in the Salinas Valley, California, where current agronomic practices depend on high nitrogen (N) rates. This study aimed to describe the postharvest fracture properties of spinach leaves in relation to N fertilization, leaf age and spinach cultivar. RESULTS: Force–displacement curves, generated by a puncture test, showed a negative correlation between N fertilization and the toughness, stiffness and strength of spinach leaves (P > 0.05). Younger leaves (leaves 12 and 16) from all N treatments were tougher than older leaves (leaves 6 and 8) (P > 0.05). Leaves from the 50 and 75 ppm total N treatments irrespective of spinach cultivar had higher fracture properties and nutritional quality than leaves from other N treatments (P > 0.05). Total alcohol‐insoluble residues (AIR) and pectins were present at higher concentrations in low‐N grown plants. These plants also had smaller cells and intercellular spaces than high‐N grown leaves (P > 0.05). CONCLUSION: Observed changes in physicochemical and mechanical properties of spinach leaves due to excess nitrogen fertilization were significantly associated with greater postharvest leaf fragility and lower nutritional quality. Copyright © 2012 Society of Chemical Industry     

Impact of surfactant type, pH and antioxidants on the oxidation of methyl linoleate in micellar solutions

The oxidation of methyl linoleate micelles has been studied, aiming at elucidating the effect of various variables, including surfactant type, pH and antioxidants. The progress of the methyl linoleate oxidation was evaluated by measurement of conjugated dienes hydroperoxides (CDHP) and malondialdehyde (MDA). It was shown that the oxidative stability of methyl linoleate micelles was influenced by surfactant type, with oxidative rate being greater in SDS micelles than in Tween 20 micelles. Besides, the methyl linoleate micelles at pH 6.8 had greater rates of lipid oxidation than their pH 3.0 counterparts. Moreover, the incorporation of VE and VC in the methyl linoleate micelles successfully slowed the formation of hydroperoxides and their subsequent decomposition product MDA. However, the antioxidant activities of VE and VC were related to their concentrations.     

Physico—chemical modifications of liposome structures through interaction with surfactantsy‡

The liposome-surfactant interaction has been studied in this paper through the disrupting effect caused by surfactant molecules on large unilamellar vesicles prepared by reverse-phase evaporation. This process leads, in the end, to the rupture of such structures and to the solubilization of the phospholipidic components, via mixed surfactant-phospholipid micelle formation. This phenomenon is described by a three-stage model and characterized by two parameters: the highest surfactant/phospholipid ratio that can exist in a vesicle (R_{e sat}) and the lowest surfactant/phospholipid ratio required to keep the lipid and surfactant in the form of mixed micelles (R_{e sat}). These parameters have been determined by spectrophotometry and ³¹P NMR spectroscopy, obtaining results in a good agreement with both techniques. The surfactants tested have been: sodium dodecyl sulfate (SDS), sodium laurylether sulfate (SLES), N-hexadecyl-trimethylammonium bromide (HTAB), octylphenol series (8–20 EO) and alkylbetaines(C-10, C-12 and C-14). Different R_{e sat} and R_{e sol} values have been obtained for each of the surfactants. This has permitted a study of the solubilizing capacity versus the phospholipidic bilayer of the different surfactants as a function of their structure.     

Reduction of Escherichia coli O157:H7 population on baby spinach leaves by liquid sanitizers

The effectiveness of various liquid sanitizers and methods of application against Escherichia coli on baby spinach was investigated. Inoculated spinach was treated with (i) Pro‐San L (commercially prepared solution containing 0.66% citric acid, 0.036% sodium dodecyl sulfate (SDS); (ii) chlorine solution (200 ppm), alone or with addition of 0.036% SDS; and (iii) aqueous solution of 0.66% levulinic acid with 0.036% SDS. Population reduction in response to these treatments ranged between 2.1 and 2.8 log CFU/g. No significant difference (p > .05) was found among tested sanitizers in microbial count reduction. Spraying, dipping, and “dry” vacuum impregnation methods of Pro‐San L application were compared. Dipping was the most effective in reducing E. coli O157:H7 population (4.4 log CFU/g reduction). Dry vacuum impregnation was less effective (3.3 log CFU/g reduction) and caused damage to the produce. The effectiveness of spray Pro‐San L application and holding for prolonged time (up to 3 days) was also evaluated. However, increasing time of exposure to organic acid sanitizer did not increase sanitizing effectiveness and led to progressive damage of spinach leaves.     

Interaction between Emulsion Droplets and Escherichia coli Cells

ABSTRACT Oil‐in‐water emulsions (20% n‐hexadecane, v/v) were stabilized by dodecyltrimethylammonium bromide (DTAB), Tween 20, or sodium dodecyl sulfate (SDS). Particle size distribution and creaming stability were measured before and after adding Escherichia coli cells to emulsions. Both E. coli strains promoted droplet flocculation, coalescence, and creaming in DTAB emulsions, although JM109 cells (surface charge = ‐35 mV) caused faster creaming than E21 cells (surface charge = ‐5 mV). Addition of bacterial cells to SDS emulsions promoted some flocculation and coalescence, but creaming stability was unaffected. Droplet aggregation and accelerated creaming were not observed in emulsions prepared with Tween 20. Surface charges of bacterial cells and emulsion droplets played a key role in emulsion stability.     

Inhibition of citral degradation in model beverage emulsions using micelles and reverse micelles

Citral is a flavour component that is widely used in the beverage, food, and fragrance industries. Citral chemically degrades over time in aqueous solutions due to acid catalysed and oxidative reactions, leading to loss of desirable flavour and the formation of off-flavours. We examined the influence of surfactant micelles (Tween 80) in the aqueous phase and reverse micelles (polyglycerol polyricinoleate, PGPR) in the oil phase on the oil–water partitioning and chemical degradation of citral in medium chain triglyceride oil-in-water emulsions. The percentage of citral in the aqueous phase of the emulsions increased with increasing Tween 80 concentration, which was attributed to its incorporation within surfactant micelles. The rate of citral degradation decreased as the Tween 80 concentration was increased from 1% to 5% w/w in both aqueous solutions and in emulsions, suggesting that citral was protected from degradation once it was incorporated into micelles. The presence of reverse micelles (5% or 10% w/w PGPR) in the oil droplets decreased the percentage of citral present within the aqueous phase of the emulsions, suggesting that citral was preferentially incorporated into the reverse micelles. In addition, the presence of reverse micelles increased the chemical stability of citral, possibly because a greater fraction remained within the oil droplets. These results show that micelle or reverse-micelle structures may be used to improve the chemical stability of citral in beverage emulsions.     

Microencapsulated antimicrobial compounds as a means to enhance electron beam irradiation treatment for inactivation of pathogens on fresh spinach leaves

Abstract: Recent outbreaks associated to the consumption of raw or minimally processed vegetable products that have resulted in several illnesses and a few deaths call for urgent actions aimed at improving the safety of those products. Electron beam irradiation can extend shelf‐life and assure safety of fresh produce. However, undesirable effects on the organoleptic quality at doses required to achieve pathogen inactivation limit irradiation. Ways to increase pathogen radiation sensitivity could reduce the dose required for a certain level of microbial kill. The objective of this study was to evaluate the effectiveness of using natural antimicrobials when irradiating fresh produce. The minimum inhibitory concentration of 5 natural compounds and extracts (trans‐cinnamaldehyde, eugenol, garlic extract, propolis extract, and lysozyme with ethylenediaminetetraacetate acid (disodium salt dihydrate) was determined against Salmonella spp. and Listeria spp. In order to mask odor and off‐flavor inherent of several compounds, and to increase their solubility, complexes of these compounds and extracts with β‐cyclodextrin were prepared by the freeze‐drying method. All compounds showed bacteriostatic effect at different levels for both bacteria. The effectiveness of the microencapsulated compounds was tested by spraying them on the surface of baby spinach inoculated with Salmonella spp. The dose (D₁₀ value) required to reduce the bacterial population by 1 log was 0.190 kGy without antimicrobial addition. The increase in radiation sensitivity (up to 40%) varied with the antimicrobial compound. These results confirm that the combination of spraying microencapsulated antimicrobials with electron beam irradiation was effective in increasing the killing effect of irradiation. Practical Application: Foodborne illness outbreaks attributed to fresh produce consumption have increased and present new challenges to food safety. Current technologies (water washing or treating with 200 ppm chlorine) cannot eliminate internalized pathogens. Ionizing radiation is a viable alternative for eliminating pathogens; however, the dose required to inactivate these pathogens is often too high to be tolerated by the fresh produce without undesirable quality changes. This study uses natural antimicrobial ingredients as radiosensitizers. These ingredients were encapsulated and applied to fresh produce that was subsequently irradiated. The process results in high level of microorganism inactivation using lower doses than the conventional irradiation treatments.     

Time-dependent competitive adsorption of milk proteins and surfactants in oil-in-water emulsions

Competitive adsorption of pure milk proteins and non-ionic surfactants has been studied in model oil-in-water emulsions (4 g kg^?1 β-lactoglobulin or β-casein, 200 g kg^?1 n-hexadecane) as a function of the age of the adsorbed protein layer at the oil-water interface. With β-lactoglobulin-stabilised emulsions containing oil-soluble surfactant C₁₂ E₂ (diethylene glycol n-dodecyl ether), there is found to be a steadily increasing amount of protein associated with the emulsion droplets over a few hours following emulsification. Addition of water-soluble surfactant Tween 20 (polyoxyethylene (20) sorbitan monolaurate) to a β-lactoglobulin-stabilised emulsion (with or without C₁₂E₂) leads to less protein displacement if the emulsion is aged prior to addition of Tween 20. Moderate additions of C₁₂E₂ or Tween 20 produce no time dependence in the competitive adsorption in β-casein-stabilised emulsions, although some time dependence is observed when C₁₂E₂ and a high concentration of Tween 20 are present together. Crystallisation of the oil phase in β-casein-stabilised emulsions at pH 7 leads to a lowering of the measured protein surface concentration, especially in the presence of C₁₂E₂ and a reduction in the surfactant to protein molar ratio required for complete protein displacement by water-soluble surfactant (Tween 20 or octaethylene glycol n-dodecyl ether). Under more acidic conditions of pH 5 or pH 3, the surface coverage and ease of displacement of β-lactoglobulin at the surface of liquid emulsion droplets is substantially different from that under neutral pH conditions.     

Characterization of interactions between Escherichia coli O157:H7 with epiphytic bacteria in vitro and on spinach leaf surfaces

This study characterized the types of interactions between Escherichia coli O157:H7 and spinach phylloepiphytic bacteria and identified those that influence persistence of E. coli O157:H7 on edible plants. A total of 1512 phylloepiphytic bacterial isolates were screened for their ability to inhibit or to enhance the growth of E. coli O157:H7 in vitro and on spinach leaf surfaces. Fifteen different genera, the majority belonging to Firmicutes and Enterobacteriaceae, reduced growth rates of E. coli O157:H7 in vitro by either nutrient competition or acid production. Reduced numbers of E. coli O157:H7 were recovered from detached spinach leaves that were co-inoculated with epiphytic isolates belonging to five genera. A 1.8 log reduction in E. coli O157:H7 was achieved when co-inoculated with Erwinina perscinia and 20% cellobiose, a carbon source used by the phylloepiphytes but not E. coli O157:H7. The reduction on leaves was significantly less than reduction measured in vitro. Phylloepiphytic bacteria belonging to eight different genera, increased numbers of E. coli O157:H7 when co-cultured in vitro on spent medium and when co-cultured on detached spinach leaves. The results, showing reduction of E. coli O157:H7 numbers by natural epiphytic bacteria, support the hypothesis that native plant microbiota can be used for bio-control of foodborne pathogens, however, other epiphytes may promote the persistence of enteric pathogens on the phyllosphere.     

Improved assay of coenzyme Q10 from liposomes by Tween 80 solubilisation and UV spectrophotometry

The encapsulated coenzyme Q₁₀ (CoQ₁₀) level is an important index in evaluating the quality of CoQ₁₀ liposomes. This study demonstrates a simple method to release encapsulated CoQ₁₀ from liposomal suspension using moderate amounts of the non‐ionic surfactant Tween 80 to form mixed micelles containing phospholipids, Tween 80 and CoQ₁₀. The encapsulated CoQ₁₀ level was detected by means of Tween 80 solubilisation and ultraviolet (UV) spectrophotometry, in which 1 mL of the reducing agent NaBH₄ (7 mg mL^?1) was added. The proposed method had a good linear correlation with ethanol solubilisation and reverse phase high‐performance liquid chromatography (RP‐HPLC) and with ethanol solubilisation and UV spectrophotometry over a CoQ₁₀ concentration range of 2.5–50 µg mL^?1 (R² > 0.999). The average recovery rate of CoQ₁₀ from blank liposomes was estimated as 99.46 ± 1.54%. The difference in results between the organic solvent extraction method and the Tween 80 solubilisation method was not statistically significant (P > 0.05). When the latter method was applied to determine the total and the encapsulated CoQ₁₀ content quantitatively, the relative standard deviation was lower than 5%. Therefore this method has proved to be convenient, sensitive, accurate and reproducible compared with conventional RP‐HPLC analysis and UV spectrophotometry with organic solvent extraction. Copyright © 2006 Society of Chemical Industry     

Development of oscillation method for reducing foodborne pathogens on lettuce and spinach

In this study, the efficacy of an oscillator for reducing the numbers of foodborne pathogens on lettuce and spinach was tested. A cocktail of three strains each of Salmonella typhimurium, Escherichia coli O157:H7 and Listeria monocytogenes cells and of Bacillus cereus spores was inoculated onto lettuce and spinach leaves and followed by oscillation at 10 Hz and 20 Hz for up to 30 s. After treatment of inoculated lettuce leaf with an oscillator at 20 Hz for 30 s, 2.58, 2.82, 2.21 and 2.22 Log₁₀ CFU/g reductions were obtained with the cells of S. typhimurium, E. coli O157:H7 and L. monocytogenes and the spores of B. cereus, respectively. In the case of the oscillation treatment of spinach leaf, 2.89, 3.73, 2.46 and 2.25 Log₁₀ CFU/g reductions of those pathogens were achieved under the same condition. Statistically significant reductions were observed after oscillation treatment at 20 Hz for 5-10 s. The oscillation treatment at 10 Hz led to slightly less reductions of the pathogens tested as compared to the treatment at 20 Hz. In conclusion, the oscillation method developed shows to be highly efficacious in reducing foodborne pathogens on lettuce and spinach leaves.     

Characteristics and antioxidant activity of leaf essential oil–incorporated fish gelatin films as affected by surfactants

Characteristics of film from fish skin gelatin incorporated with four leaf essential oils (lemongrass, basil, citronella and kaffir lime), as influenced by different surfactants (Tween‐20, Tween‐80 and soy lecithin), were investigated. Films incorporated with all essential oils had lower tensile strength with higher elongation at break and thickness, compared with control film (P < 0.05). Films added with Tween‐20 showed higher TS, compared with those containing other surfactants (P < 0.05). Water vapour permeability of films incorporated with all essential oils markedly decreased in comparison with control (P < 0.05). Films generally became darker and more yellowness, when incorporated with essential oils. Film containing basil essential oil had the highest DPPH radical– and ABTS radical–scavenging activities, compared with those added with other essential oils. Higher antioxidative activity was obtained in films containing essential oils when soy lecithin was used as surfactant, probably due to the combined effect of both constituents.     

Antifungal activity of five different essential oils in vapour phase for the control of Colletotrichum gloeosporioides and Lasiodiplodia theobromae in vitro and on mango

Mango fruit has high commercial value; however, major postharvest losses are encountered throughout the supply chain due to postharvest diseases. These results lead to the search for natural fungicide for postharvest diseases control. The antifungal effects of five essential oils (thyme, clove, cinnamon, anise and vitex) were assessed by disc volatilisation method. Thyme oil vapours at 5 μL per Petriplate, and clove and cinnamon oil at 8 μL per Petriplate showed 100% growth inhibition of mango pathogens in vitro. GC/MS analysis of essential oil showed thymol (23.88), o‐cymol (23.88) and terpinolene (23.88) as the major constituents of thyme oil. Clove and cinnamon oils contain 3‐allyl‐2‐methoxyphenol (37.42%) and benzofuran 3‐methyl (17.97%), respectively. Thyme oil as a fumigant at 66.7 μL L^?1 showed a significant (P < 0.05) inhibition on postharvest pathogens of mango fruits stored at 25 °C for 6 days. Results of our study suggest the possibility of using thyme oil as an alternate natural fungicide to manage postharvest diseases in mango.