不同温度烘烤坛紫菜的体外模拟消化研究

为探究不同温度烘烤下坛紫菜的消化情况,本试验通过构建体外消化模型,对不同消化过程中坛紫菜的细胞形态进行观察并测定其营养物质含量和抗氧化活性,分析不同温度烘烤后坛紫菜在消化过程中的变化规律。结果表明,不同温度烘烤的坛紫菜经口胃肠连续消化后,细胞裂解有差异,其中180℃和200℃处理组的坛紫菜细胞裂解程度大。体外消化结果表明,坛紫菜的游离氨基酸含量释放主要集中在胃肠道中,可溶性糖及还原糖主要集中在胃消化过程中,抗氧化活性在胃消化过程中表现最强,其中180℃烘烤坛紫菜的营养物质释放量和抗氧化活性最佳,200℃处理组次之。本研究结果为提高坛紫菜的生物利用率以及评价其不同加工模式提供了一定的理论依据。     

Effect of in vitro enzymatic digestion on antioxidant activity of coffee melanoidins and fractions

Traditionally antioxidant activity of melanoidins has only been evaluated in food for implication in shelf life but gastrointestinal digestion is necessary to study their potential bioactivity. In addition, the biological fate of melanoidins has been stressed during the past decade since they did not behave as inert substances. In the present paper a soluble coffee melanoidin isolated from brewed coffee after ultrafiltration with a 10 kDa cutoff membrane was treated ionically and enzymatically collecting the respective high and low molecular weight fractions. Antioxidant activity of these fractions was evaluated with five well-described assays (DPPH, ABTS, ORAC, HOSC, and FRAP) that were previously setup in a plate reader based automatized analysis. Low molecular weight compounds released from melanoidin after gastrointestinal digestion exerted the highest antioxidant activity, even higher than compounds bound ionically to melanoidins. Gastrointestinal digestion is able to modify coffee melanoidins to some extent, as hypothesized from their absolute antioxidant activities. Two options are plausible: by modifying/releasing the ionically bound compounds and/or by genesis of new more active structures from the melanoidin skeleton after enzymatic treatment.     

Electron spin resonance and luminescence spectroscopic observation and kinetic study of chemical and physical singlet oxygen quenching by resveratrol in methanol

Electron spin resonance (ESR) spectroscopy and near-infrared (NIR) fluorescence spectroscopy were performed to observe singlet oxygen quenching by resveratrol. Resveratrol greatly decreased the 2,2,6,6-Tetramethyl-4-piperidone-N-oxyl radical signal as determined by ESR spectroscopy. Resveratrol also efficiently decreased luminescence emission at 1268 nm as studied with a NIR spectrofluorometer, showing positive evidence of singlet oxygen quenching by resveratrol. The total singlet oxygen quenching rate constant (kr+kq) of resveratrol in methanol was determined to be 2.55×10(7) M(-1) s(-1). The singlet oxygen chemical quenching rate constant (kr) of resveratrol was calculated by measuring its reaction rate with singlet oxygen relative to that of α-terpinene in the same solution under light illumination. The kr value of resveratrol was 1.15×10(6) M(-1) s(-1). The percent partition of chemical quenching over total singlet oxygen quenching (kr×100)/(kr+kq) for resveratrol was 5.11%. The results showed that resveratrol quenches singlet oxygen almost exclusively through the mechanism of physical quenching. Resveratrol showed a protective activity similar to that of BHA on the methylene blue sensitized photooxidation of α-terpinene. This unambiguously explains the mechanism of how resveratrol protects tissues and cells in biological systems or important nutrients in food systems against their photosensitized oxidations.     

Cellular antioxidant activity of feijoada whole meal coupled with an in vitro digestion

Consumption of plant food rich meals, such as feijoada, a traditional meal in Brazil, is associated with the reduction of chronic disease. The objectives of this study were to determine phytochemical content and antioxidant activity by chemical and cellular antioxidant assays (CAA) of feijoada with or without in vitro digestion. Feijoada showed no difference in phenolics and flavonoids after digestion. Bound and residue contributions to total phenolics were 20.9% and 32.2%, respectively, suggesting that phenolics reach the colon after intake. Flavonoids in residue and bound fractions represented 50% of total flavonoids. Antioxidant activity of feijoada without digestion was higher than that with digestion; however, it showed lower antiproliferative activity and CAA. Feijoada with in vitro digestion also yielded phenolics with higher CAA. Analyses of whole meals should be used to evaluate phytochemicals present in food mixtures consumed, especially with digestion models coupled with CAA resulting in information similar to those in physiological conditions.     

Identification of hen egg yolk-derived phosvitin phosphopeptides and their effects on gene expression profiling against oxidative stress-induced Caco-2 cells

Oxidative stress is involved in the initiation and propagation of chronic intestinal pathologies. Bioactive peptides such as egg yolk-derived phosvitin phosphopeptides (PPP3) have been previously shown to reduce in vitro oxidative stress by up-regulating glutathione synthesis and antioxidant enzyme activities. Peptide and gene expression profile analysis of the PPP3 peptides can provide insight into structures involved in signal transduction mechanisms in the antioxidative stress response. The objectives of this research were to identify the PPP3 amino acid sequences before and after simulated gastrointestinal digestion and to assess the genes influenced by PPP3. Peptide sequences were analyzed using ESI Q-TOF-MS/MS, and the expression profile of 84 human oxidative stress and antioxidant defense genes were analyzed. Undigested PPP3 was composed of three main peptides: GTEPDAKTSSSSSSASSTATSSSSSSASSPNRKKPMDE (phosvitin-PV residues 4-41), NSKSSSSSSKSSSSSSRSRSSSKSSSSSSSSSSSSSSKSSSSR (PV residues 155-197), and EDDSSSSSSSSVLSKIWGRHEIYQ (PV residues 244-257) and their fragments. There was limited degradation of PPP3 after gastrointestinal digestion as deduced from the fragment sizes of digested PPP3, which ranged from 5 to 32 amino acids. These fragments were rich in contiguous serines and, in some cases, monoesterified with phosphate. Both undigested and digested PPP3 significantly reduced IL-8 secretion in H(2)O(2)-induced Caco-2 cells, indicating that antioxidative stress bioactivity is retained upon digestion. After PPP3 pretreatment, antioxidant genes associated with oxygen and reactive oxygen species (ROS) metabolism and cellular responses to chemical stimulus, oxidative stress, and ROS are up-regulated in the presence and absence of oxidative stress, thereby contributing to the prevention of intestinal oxidative stress and the promotion of gut health.     

Angiotensin converting enzyme inhibitory activity in commercial fermented products. Formation of peptides under simulated gastrointestinal digestion

The angiotensin converting enzyme (ACE)-inhibitory activity of several commercial fermented milks was evaluated. Most of these products showed moderate inhibitory activity, but a few exceptions were detected. The high ACE-inhibitory activity found in some cases could be related to the origin of the milk. Two of these products were subjected to an enzymatic hydrolysis process, which simulates physiological digestion, to study the influence of digestion on ACE-inhibitory activity. The activity did not significantly change or increase during simulated gastrointestinal digestion. The peptides generated from one selected product during simulated digestion were sequenced by tandem spectrometry. Most peptides found at the end of the simulated digestion were released after 30 min of incubation with the pancreatic extract. This suggests that physiological digestion promotes the formation of active peptides from the proteins present in these fermented products. The potential ACE-inhibitory activity of the identified peptides is discussed with regard to their amino acid sequences.     

Release of angiotensin I converting enzyme (ACE) inhibitory activity during in vitro gastrointestinal digestion: from batch experiment to semicontinuous model

Gastrointestinal digestion is of major importance in the bioavailability of angiotensin I converting enzyme (ACE) inhibitory peptides, bioactive peptides with possible antihypertensive effects. In this study, the conditions of in vitro gastrointestinal digestion leading to the formation and degradation of ACE inhibitory peptides were investigated for pea and whey protein. In batch experiments, the digestion simulating the physiological conditions sufficed to achieve the highest ACE inhibitory activity, with IC(50) values of 0.076 mg/mL for pea and 0.048 mg/mL for whey protein. The degree of proteolysis did not correlate with the ACE inhibitory activity and was always higher for pea than whey. In a semicontinuous model of gastrointestinal digestion, response surface methodology studied the influence of temperature and incubation time in both the stomach and small intestine phases on the ACE inhibitory activity and degree of proteolysis. For pea protein, a linear model for the degree of proteolysis and a quadratic model for the ACE inhibitory activity could be constituted. Within the model, a maximal degree of proteolysis was observed at the highest temperature and the longest incubation time in the small intestine phase, while maximal ACE inhibitory activity was obtained at the longest incubation times in the stomach and small intestine phase. These results show that ACE inhibitory activity of pea and whey hydrolysates can be controlled by the conditions of in vitro gastrointestinal digestion.     

Angiotensin I converting enzyme inhibitory peptides from in vitro pepsin-pancreatin digestion of soy protein

Angiotensin I converting enzyme (ACE) inhibitory activity was determined in the soy protein isolate (SPI) digest produced by in vitro pepsin-pancreatin sequential digestion. The inhibitory activity was highest within the first 20 min of pepsin digestion and decreased upon subsequent digestion with pancreatin. An IC(50) value of 0.28 +/- 0.04 mg/mL was determined after 180 min of digestion, while no ACE inhibitory activity was measured for the undigested SPI at 0.73 mg/mL. Chromatographic fractionation of the SPI digest resulted in IC(50) values of active fractions ranging from 0.13 +/- 0.03 to 0.93 +/- 0.08 mg/mL. Although many of the fractions showed ACE inhibition, peptides with lower molecular masses and higher hydrophobicities were most active. The findings show that many different peptides with ACE inhibitory activities were produced after in vitro pepsin-pancreatin digestion of SPI and lead to the speculation that physiological gastrointestinal digestion could also yield ACE inhibitory peptides from SPI.     

Effect of simulated gastrointestinal digestion on the antihypertensive properties of ACE-inhibitory peptides derived from ovalbumin

Food-derived bioactive peptides with ACE-inhibitory properties are receiving special attention due to their beneficial effects in the treatment of hypertension. In this work we evaluate the impact of a simulated gastrointestinal digestion on the stability and activity of two bioactive peptides that derive from ovalbumin by enzymatic hydrolysis, YAEERYPIL and RADHPFL. These peptides possess in vitro ACE-inhibitory activity and antihypertensive activity in spontaneously hypertensive rats (SHR). The results showed that YAEERYPIL and RADHPFL were susceptible to proteolytic degradation after incubation with pepsin and a pancreatic extract. In addition, their ACE-inhibitory activity in vitro decreased after the simulated digestion. The antihypertensive activity on SHR of the end products of the gastrointestinal hydrolysis, YAEER, YPI, and RADHP, was evaluated. The fragments YPI and RADHP significantly decreased blood pressure, 2 h after administration, at doses of 2 mg/kg, but they probably did not exert their antihypertensive effect through an ACE-inhibitory mechanism. It is likely that RADHP is also the active end product of the gastrointestinal digestion of the antihypertensive peptides FRADHPFL (ovokinin) and RADHPF (ovokinin 2-7).     

Chemical and biochemical transformations during the industrial process of sherry vinegar aging

The work described here concerns a study of the chemical and biochemical transformations in sherry vinegar during the different aging stages. The main factors that contribute to the nature and special characteristics of sherry vinegar are the raw sherry wine, the traditional process of acetic acid fermentation in butts (the solera system), and the physicochemical activity during the aging process in the solera system. A number of chemical and biochemical changes that occur during sherry vinegar aging are similar to those that take place in sherry wine during its biological activity process (where the wine types obtained are fino and manzanilla) or physicochemical activity process (to give oloroso wines). Significant increase in acetic acid levels was observed during the biological activity phase. In addition, the concentrations of tartaric, gluconic, succinic, and citric acids increased during the aging, as did levels of amino acids and acetoin. A color change was also produced during this stage. Glycerol was not consumed by acetic acid bacteria, and levels of higher alcohols decreased because of the synthesis of acetates. On the other hand, in the physicochemical phase the microbiological activity was lower. Concentrations of some cations increased because of evaporation of water through the wood. A color change was also produced in this stage. Concentrations of different amino acids decreased because of reaction with carbonyl compounds. A precipitation of potassium with tartaric acid was also observed.     

Effect of some phenolic compounds and beverages on pepsin activity during simulated gastric digestion

The effect of some polyphenols (resveratrol, catechin, epigallocatechin-3-gallate, and quercetin) and beverages (red wine and green tea) on the enzymatic activity of pepsin during the digestion of three different substrates (pork meat, insoluble azocasein, and denatured hemoglobin) has been investigated. The tested polyphenols and beverages increase the initial velocity of the reaction, and the activating effect is concentration dependent. The order of effectiveness of polyphenols in increasing the initial velocity of the reaction is resveratrol > or = quercetin > epigallocatechin-3-gallate > catechin. The kinetic data obtained with soluble denatured hemoglobin show that the K(m) for the substrate is not changed, whereas the V(max) of the reaction is increased. Pepsin activity follows a simple Michaelis-Menten kinetic suggesting that k(3) is increased by polyphenols. To the authors' knowledge, the present study is the first demonstration that some polyphenols and related beverages are able to enhance the enzymatic activity of pepsin.     

Inhibition of gastrointestinal lipolysis by green tea, coffee, and gomchui (Ligularia fischeri) tea polyphenols during simulated digestion

Green tea, coffee, and gomchui (Ligularia fischeri) tea, which are rich in polyphenols, may exhibit antiobesity effects by inhibiting pancreatic lipase. However, the bioavailability of some polyphenols is poor due to either degradation or absorption difficulties in the gastrointestinal tract, thus making their beneficial effects doubtful. This study was conducted to evaluate the inhibitory effect of three beverages on lipolysis and the contribution of their major polyphenols during simulated digestion. During simulated digestion, gomchui tea was the most potent at inhibiting gastrointestinal lipolysis, whereas green tea was the least potent. The strongest lipase inhibitor among purified major polyphenols was a green tea polyphenol, (-)-epigallocatechin gallate (EGCG, IC(50) = 1.8 ± 0.57 μM), followed by di-O-caffeoylquinic acid isomers (DCQA, IC(50) from 12.7 ± 4.5 to 40.4 ± 2.3 μM), which are gomchui tea polyphenols. However, the stability of DCQA was greater than that of EGCG when subjected to simulated digestion. Taken together, gomchui tea, which has DCQA as the major polyphenol, showed stronger lipolysis inhibitory activity during simulated digestion compared to both green tea and coffee.     

Antioxidant activity of A-type proanthocyanidins from Geranium niveum (Geraniaceae)

Geranium niveum S. Watson (Geraniaceae) is a medicinal herb widely used by the Tarahumara Indians of Mexico. This species is rich in proanthocyanidins and other phenolics. Previous in vitro assays have demonstrated that proanthocyanidins exhibited antiinflammatory, antiviral, antibacterial, enzyme-inhibiting, antioxidant, and radical-scavenging properties. In view of its medicinal use and chemical composition, the aim of the present study was to determine the in vitro antioxidant activity of the extracts and two proanthocyanidins (geranins A and D) from the roots of G. niveum by using seven different assay systems, namely, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion (O2*-), hydrogen peroxide (H2O2), hydroxyl radical (OH*), hypochlorous acid (HOCl), and singlet oxygen ((1)O2). Two known antioxidants, resveratrol and ascorbic acid, were used as positive controls. The results showed that geranins A and D and the extracts were able to scavenge ABTS, DPPH, O2*-, OH*, and HOCl. The scavenging ability of geranins A and D was similar to that of resveratrol and ascorbic acid in the following assays: ABTS, O2*-, and HOCl. The scavenging capacity of ascorbic acid for DPPH was higher than that of both geranins and resveratrol. On the other hand, the OH* scavenging action of both geranins and resveratrol was similar. The methanol-CHCl3 (1:1) extract had a higher ability to scavenge ABTS, DPPH, and O2*- radicals than the chloroform extract. In turn, the latter was more potent than the methanol-CHCl3 (1:1) extract as OH* or HOCl scavenger agent. Neither geranins A and D nor the extracts were able to scavenge H2O2 and (1)O2. In conclusion, G. niveum roots have proanthocyanidins with powerful radical scavenging in vitro activity. This property may partially explain the wide use of this plant in the Tarahumara indigenous system of medicine for the treatment of gastrointestinal illnesses (other than spasms), pain, and fevers associated with oxidative stress.     

Resveratrol is a potent inhibitor of the dioxygenase activity of lipoxygenase

Resveratrol is a naturally occurring phytoalexin, present in grapes and other food products, with important antioxidant properties. Although still under debate, it is generally assumed that resveratrol has protective effects against heart diseases and probably tumor development. Lipoxygenase is a dioxygenase with peroxidase activity involved in the synthesis of mediators in inflammatory, atherosclerotic, and carcinogenic processes. Lipoxygenase activity is also involved in the generation of flavors and aromas in foods from animal or vegetal sources. The results presented here show that resveratrol was a potent inhibitor of the dioxygenase activity of lipoxygenase, with an IC(50) = 13 microM. Simultaneously, resveratrol was oxidized by the peroxidase activity of lipoxygenase with a V(max) = 0.28 microM min(-1) and a k(M) = 16.6 microM. Furthermore, oxidized resveratrol was as efficient a lipoxygenase inhibitor as in its reduced form. From the data obtained it can be concluded that both resveratrol and its oxidized form can act as inhibitors of the dioxygenase activity of lipoxygenase. In contrast, the hydroperoxidase activity of lipoxygenase was not inhibited by resveratrol. These results suggest that resveratrol may be used as an antioxidant food additive and as a pharmacological agent to prevent the generation of eicosanoids involved in pathological processes.     

Phospholipid interactions protect the milk allergen alpha-lactalbumin from proteolysis during in vitro digestion

Interactions with food components may alter the resistance of food proteins to digestion, a property thought to play an important role in determining allergenic properties. The kinetics of breakdown of the bovine milk allergen alpha-lactalbumin during in vitro gastrointestinal digestion was found to be altered by interactions with physiologically relevant levels of phosphatidylcholine (PC), a surfactant that is abundant both in milk and is actively secreted by the stomach. Breakdown during gastric digestion was slowed in the presence of PC and accompanied by small alterations in the profile of resulting peptides, with little effect being observed during subsequent duodenal digestion. alpha-Lactalbumin was found to unfold at gastric (acid) pH, giving a CD spectrum similar to that obtained for the partially folded state it is known to adopt at pH values below its isoelectric point. Fluorescence polarization studies performed at low pH indicated that this partially unfolded form of the protein was able to penetrate into the PC vesicles. These interactions are probably responsible for the slowing of gastric digestion by reducing the accessibility of the protein to pepsin. These findings show that interactions with other food components, such as lipids, may alter the rate of breakdown of food proteins in the gastrointestinal tract. It underlines the importance of the food matrix in affecting patterns of food allergen digestion and hence presentation to the immune system and that in vitro digestion systems used for assessing digestibility of allergens must take account of surfactants.     

Protein-stabilized nanoemulsions and emulsions: comparison of physicochemical stability, lipid oxidation, and lipase digestibility

The properties of whey protein isolate (WPI) stabilized oil-in-water (O/W) nanoemulsions (d(43) ≈ 66 nm; 0.5% oil, 0.9% WPI) and emulsions (d(43) ≈ 325 nm; 0.5% oil, 0.045% WPI) were compared. Emulsions were prepared by high-pressure homogenization, while nanoemulsions were prepared by high-pressure homogenization and solvent (ethyl acetate) evaporation. The effects of pH, ionic strength (0-500 mM NaCl), thermal treatment (30-90 °C), and freezing/thawing on the stability and properties of the nanoemulsions and emulsions were compared. In general, nanoemulsions had better stability to droplet aggregation and creaming than emulsions. The nanoemulsions were unstable to droplet flocculation near the isoelectric point of WPI but remained stable at higher or lower pH values. In addition, the nanoemulsions were stable to salt addition, thermal treatment, and freezing/thawing (pH 7). Lipid oxidation was faster in nanoemulsions than emulsions, which was attributed to the increased surface area. Lipase digestibility of lipids was slower in nanoemulsions than emulsions, which was attributed to changes in interfacial structure and protein content. These results have important consequences for the design and utilization of food-grade nanoemulsions.     

Antioxidants, free radicals, storage proteins, puroindolines, and proteolytic activities in bread wheat (Triticum aestivum) seeds during accelerated aging

Seeds of bread wheat were incubated at 40 degrees C and 100% relative humidity for 0, 3, 4, 6, and 10 days. The effects of accelerated aging on seed germinability and some biochemical properties of flour (carotenoid, free radical, and protein contents and proteolytic activity) and gluten (free radical content and flexibility) were investigated. Seed germinability decreased during aging, resulting in seed death after 10 days. A progressive decrease of carotenoid content, in particular, lutein, was observed, prolonging the incubation, whereas the free radical content increased in both flour and gluten. A degradation of soluble and storage proteins was found, associated with a marked increase of proteolytic activity and a loss of viscoelastic properties of gluten. On the contrary, puroindolines were quite resistant to the treatment. The results are discussed in comparison with those previously obtained during accelerated aging of durum wheat seeds.     

Degradation of phytate by high-phytase Saccharomyces cerevisiae strains during simulated gastrointestinal digestion

Hydrolysis of extracellular phytate (InsP(6)) by high-phytase yeast strains and survival of yeast cells were studied at simulated digestive conditions using yeast peptone dextrose growth medium and wheat gruel as model meals. An in vitro digestion method was modified to better correlate with the gastric pH gradient following food intake in vivo. High-phytase yeast gave a strong reduction of InsP(6) (up to 60%) in the early gastric phase, as compared to no degradation by wild-type strains. The degree of InsP(6) degradation during digestion was influenced by the type of yeast strain, cell density, and InsP(6) concentration. Despite high InsP(6) solubility, high resistance against proteolysis by pepsin, and high cell survival, degradation in the late gastric and early intestinal phases was insignificant. Dependency on pH for phytase expression and/or activity seemed thus to be an important limiting factor. Although further studies are needed, our results show the potential of using yeast as a phytase carrier in the gastrointestinal tract.     

Effects of antioxidants on rapeseed oil oxidation in an artificial digestion model analyzed by UHPLC-ESI-MS

A normal diet contains large quantities of oxidized fatty acids, glycerolipids, cholesterol, and their cytotoxic degradation products because many foods in the diet are fried, heated, or otherwise processed and consumed often after long periods of storage. There is also evidence that the acid medium of the stomach promotes lipid peroxidation and that the gastrointestinal tract is a major site of antioxidant action, as demonstrated by various colorimetric methods. The identity and yields of specific products of lipid transformation have seldom been determined. The present study describes the molecular species profiles of all major gastrointestinal lipids formed during digestion of autoxidized rapeseed oil in an artificial digestion model in the presence of L-ascorbic acid, 6-palmitoyl-O-L-ascorbic acid, 3,5-di-tert-butyl-4-hydroxytoluene (BHT), DL-α-tocopherol, and DL-α-tocopheryl acetate. Differences in oxidized lipid profiles were detected in the samples digested in the presence of different antioxidants, but none of them could prevent the formation of oxidized lipids or promote their degradation in a gastric digestion model. The lack of effect is attributed to the inappropriate nature of the gastrointestinal medium for the antioxidant activity of these vitamins and BHT. A fast ultrahigh performance liquid chromatographic-electrospray ionization-mass spectrometric method was developed for the analysis of lipolysis products, including epoxy, hydroperoxy, and hydroxy fatty acids, and acylglycerols, utilizing lithium as ionization enhancer.     

Influence of surfactant charge on antimicrobial efficacy of surfactant-stabilized thyme oil nanoemulsions

Thyme oil-in-water nanoemulsions stabilized by a nonionic surfactant (Tween 80, T80) were prepared as potential antimicrobial delivery systems (pH 4). The nanoemulsions were highly unstable to droplet growth and phase separation, which was attributed to Ostwald ripening due to the relatively high water solubility of thyme oil. Ostwald ripening could be inhibited by incorporating ≥75% of corn oil (a hydrophobic material with a low water solubility) into the nanoemulsion droplets. The electrical characteristics of the droplets in the nanoemulsions were varied by incorporating ionic surfactants with different charges after homogenization: a cationic surfactant (lauric arginate, LAE) or an anionic surfactant (sodium dodecyl sulfate, SDS). The antifungal activity of nanoemulsions containing positive, negative, or neutral thymol droplets was then conducted against four strains of acid-resistant spoilage yeasts: Zygosaccharomyces bailli, Saccharomyces cerevisiae, Brettanomyces bruxellensis, and Brettanomyces naardenensis. The antifungal properties of the three surfactants (T80, LAE, SDS) were also tested in the absence of thymol droplets. Both ionic surfactants showed strong antifungal activity in the absence of thymol droplets, but no antimicrobial activity in their presence. This effect was attributed to partitioning of the antimicrobial surfactant molecules between the oil droplet and microbial surfaces, thereby reducing the effective concentration of active surfactants available to act as antimicrobials. This study shows oil droplets may decrease the efficacy of surfactant-based antimicrobials, which has important consequences for formulating effective antimicrobial agents for utilization in emulsion-based food and beverage products.