Rheology of emulsion-filled alginate microgel suspensions

Emulsion filled polysaccharide gels can be used as carrier systems of lipophilic bioactives in the food, pharmaceutical and cosmetics industry. This carrier system can exist either as bulk or discrete gel systems. In this study the rheological properties of discrete emulsion filled alginate microgel suspension was examined as a function of volume fraction (ϕ) and oil content. Fine emulsion (220 nm) was encapsulated within alginate microgels (mean size 36.2–57.8 μm) by using the impinging aerosol technique. The microgels (containing 0–77% w/w oil total solids basis) produced were estimated to have particle modulus in the range of 150–212 Pa. An increase in oil content in the microgels led to more deformable microgels due to the reduction in gel density. The deformability of microgels influenced the bulk modulus and apparent viscosity of the concentrated suspension. At the same suspension volume fraction (ϕ), suspensions with more deformable microgels exhibited a lower bulk modulus. We also showed that the Carreau and Cross models were adequate in predicting the flow behaviour of the concentrated emulsion filled microgel suspension.     

Role of Melissa officinalis in cholesterol oxidation: Antioxidant effect in model systems and application in beef patties

Cholesterol oxidation products (COPs) constitute a known health risk factor. The antioxidant effect of a lyophilized aqueous Melissa officinalis extract against cholesterol degradation and COPs formation during a heating treatment was evaluated in a model system (180 °C, 0–180 min) at a ratio of 2 mg extract/100 mg cholesterol. Furthermore, the plant extract was subsequently added to beef patties alone or incorporated within an oil-in-water olive oil emulsion to assess its effectiveness during cooking. Melisa extract protected cholesterol from thermal degradation in the model system, yielding higher remaining cholesterol and lower COPs values throughout the whole heating process. Maximum total COPs were achieved after 30 and 120 min of heating for control and melisa-containing samples, respectively. In cooked beef patties, even though the olive oil emulsion was used as flavor-masking approach, melisa extract off-flavor limited the maximum dose which could be added. At these doses (65 μg/g and 150 μg/g without and with the emulsion, respectively), no additional protective effect of melisa over the use of the emulsion was found. Addition of natural extracts into functional foods should definitively take into account sensory aspects.     

High pressure pre-treatment of Moringa oleifera seed kernels prior to aqueous enzymatic oil extraction

High pressure processing (HPP) was applied as a pre-treatment on Moringa oleifera (MO) kernels, for the first time, prior to aqueous enzymatic extraction (AEE) of the MO oil, and the effect of this pre-treatment is reported in terms of the free oil recovery and the nature of the cream emulsions formed. The HPP pre-treatments (50–250 MPa, 20–60 °C, 10–60 min) generally resulted in higher free oil recoveries and thinner emulsion layers from ground-sieved kernels than the whole kernels. Optimization of the HPP parameters indicated linear increment in free oil recovery with increase in temperature and time, but not the pressure level. Without the pre-boiling step in the AEE process, the use of HPP pre-treatment at 50 MPa and 60 °C for 35 min resulted in approximately 73% (w/w) free oil recovery with thinner emulsion layer than the use of AEE alone. These findings highlighted the ability of HPP in altering the MO protein structure into a form of less emulsifying functional properties, thus further de-emulsification method may not be necessary.Industrial relevanceHigh pressure processing (HPP) applications are increasing in the food industry. High pressure application allows the use of relatively lower temperatures in processes, in order to achieve comparable outcomes of higher temperature processing. This study explores the application of HPP on Moringa oleifera (MO) kernels prior to aqueous enzymatic extraction (AEE) of oil. In general, the main disadvantage of AEE is its lower oil recovery in comparison with solvent extraction, which is attributed to the formation of a relatively stable cream emulsion after extraction. This study shows that the thickness of the creamy emulsion can be significantly reduced, and oil recoveries improved, by subjecting the kernels to HPP prior to extraction. The improvement in recoveries did not depend strongly on the level of high pressure applied, but downstream processes for free oil separation and recovery were considerably simplified.     

Availability of lactoferrin as a natural solubilizer of iron for food products

Lactoferrin (LF) was investigated as a natural solubilizer of iron. Under neutral conditions, 1 mole of LF solubilized 200 moles of iron. In a single dose oral toxicity study, 2.5 g iron solubilized by lactoferrin (FeLF) per kg body weight had no side effects on the rat gastric mucosa, while ferrous sulphate and ferrous citrate (at the same level with respect to iron) caused some serious injuries. FeLF was orally administered to rats for 28 days to investigate its potential toxicity. Haemoglobin content and its regeneration efficiency in rats fed with FeLF were superior to those observed with ferrous sulphate, which is the most frequently used iron supplement. The availability of FeLF in a rat model of iron-deficiency anaemia was demonstrated. LF is useful as a natural iron solubilizer for food products and neutraceuticals from the viewpoints of safety, bioavailability, and productivity.     

Physical characteristics of submicron emulsions upon partial displacement of whey protein by a small molecular weight surfactant and pectin addition

O/W emulsions (6 wt.% olive oil) were prepared at pH 3.3 using different WPI:Tween 20 weight ratios (1:0, 3:1, 1:1, 1:3, 0:1) at 1 wt.% total concentration. The emulsion droplet size was found to decrease with an increase in Tween 20. A minimum droplet size of d_3,2 300 nm was found for Tween systems alone, similar to that found (360 nm) for a 1:1 WPI:Tween 20 combination (p < 0.05). This specific composition showed a value for the interfacial tension close to that of Tween 20 alone. However, the emulsions presented low stability regardless of the WPI:Tween 20 ratio. To increase their stability, pectin was added, in various concentrations (0.2, 0.4 and 0.6 wt.%), using the Layer by Layer technique. In the presence of pectin, the ζ-potential of the oil droplets became negative; indicating that negatively charged pectin was absorbed onto the positively-charged droplet surface forming a secondary layer. The additional layer resulted in a wide range of emulsion stability. For all pectin concentrations, the 1:1 ratio of WPI:Tween 20 showed the highest stability. In most emulsions, extensive aggregation of oil droplets was observed, and their viscosity increased. Insufficient amounts of pectin to form the secondary layers led to bridging flocculation phenomena of oppositely charged pectin and proteins, leading to aggregation of the oil droplets. The higher the concentration of pectin, the greater the stability of the emulsion due to higher viscosity. All in all, the addition of a second layer consisting of pectin can be used to increase the stability of an emulsion containing emulsion droplets in the sub-micron range.     

Stability of flocculated particles in concentrated and high hydrophilic solid layer-by-layer (LBL) emulsions formed using whey proteins and gum Arabic

The objective of the present study was to investigate flocculation in layer-by-layer (LBL) emulsion systems with high total solids content and deflocculation at various pH conditions, and the effects of whey protein isolate (WPI) concentration and total solids content on the stability of LBL emulsions. WPI (1.96% (1WPI) or 10.71% (10WPI), w/w in water) was prepared in water and high-pressure homogenized with sunflower oil (10%, w/w, of total emulsion). Gum Arabic (0.15%, w/w, in total emulsion) was added to assemble electrostatically on WPI at oil particle interfaces at pH 3.5 using aqueous citric acid (10% w/w) forming LBL emulsion. The ζ-potential measurements showed charge reversal upon addition of gum Arabic solution into single layer (SL) emulsion confirming the formation of LBL interface. Trehalose:maltodextrin mixture (1:1, w/w, total emulsion, 28.57% (28) or 57.14% (57), w/w, in water) was used in the continuous phase. The high total solids content of the system results in depletion flocculation of the particles leading to bridging flocculation without coalescence as deflocculation into individual particles occurred with increasing pH from pH 3.5 to pH 6.5 in 10WPI systems. Deflocculation was evident in 10WPI-28 and 10WPI-57 as found from a decreased ζ-average diameter and visually under microscope. Coalescence was observed in 1WPI systems. Viscosity of the systems was significantly (P < 0.05) increased with higher total solids content. Accelerated destabilization test showed that systems at higher WPI and total solids contents exhibited the highest stability against creaming. Deflocculation in LBL systems can be controlled by pH while high solids in the aqueous phase provide stability against creaming.     

In vitro digestion of foods using pH-stat and the INFOGEST protocol: Impact of matrix structure on digestion kinetics of macronutrients,proteins and lipids

It is currently admitted that food structure can facilitate or delay the release of nutrients during digestion and their absorption by the human body. The aim of this study is to propose an in vitro method able to assess the behavior of lipo-proteinic matrices with different structures during digestion. Two model matrices of exactly the same compositions (10% oil, 15% whey proteins, w/w) were designed: i) A liquid emulsion (LE) made of small fat droplets (1 μm) dispersed in a liquid continuous phase containing native whey proteins, ii) a solid emulsion (SE) made of a continuous whey protein gel entrapping large oil droplets (20 μm). The two matrices were digested through an in vitro gastro-intestinal protocol based on the INFOGEST guidelines using pH-stat to monitor the enzymatic hydrolyses of both proteins and lipids. By further digesting lipid-free matrices in the same conditions, the contributions of the proteolytic and lipolytic reactions were evaluated. Significant differences were observed between matrices at both short and long digestion times. The initial rates of both proteolysis and lipolysis were slower for SE than LE because of the gel state of the continuous phase. At the end of the experiments, SE led to a smaller extent of lipolysis (DH_{lip_SE} = 51% < DH_{lip_LE} = 81%) but a greater extent of proteolysis (DH_{prot_SE} = 80% > DH_{prot_LE} = 52%) because of the higher sensitivity to digestion of denatured whey proteins. These results highlight the impact of matrix structure on enzyme accessibility, and show that the proposed method is suitable to monitor the digestion of complex food matrices.     

Improving intracellular uptake of 5-demethyltangeretin by food grade nanoemulsions

5-Demethyltangeretin (5DT) is a unique citrus flavonoid that has been shown to have anti-cancer effects, but its low water-solubility and poor oral bioavailability may limit its application as a nutraceutical. In this study, we utilized emulsion-based delivery systems to increase the bioavailability of 5DT and its uptake by intestinal cancer cells. Oil-in-water emulsions with different mean droplet radii (r = 67, 125 and 203 nm) were fabricated using high-pressure homogenization. The amount of 5DT absorbed by intestinal cancer cells was quantified by HPLC using an electrochemistry detector. The relative percentages of 5DT absorption compared to a reference emulsion (r = 67 nm) were: 5.9% (in water, crystal); 13.1% (in medium chain triglyceride (MCT), crystal); 30.6% (emulsion, r = 203 nm); and 92.9% (emulsion, r = 125 nm). A cytotoxicity assay showed that 5DT encapsulated in smaller droplets produced stronger growth inhibition than those in larger droplets, and much higher than those dispersed in bulk MCT or bulk water. 5DT encapsulated within emulsions with small droplet sizes (nanoemulsions) produced higher cellular absorption and lower cancer cell viability. Our results suggested that this type delivery system may be useful for the application of 5DT and other similar nutraceuticals in functional foods and beverages.     

Ultrasound-assisted encapsulation of annatto seed oil: Retention and release of a bioactive compound with functional activities

This paper brings forward the encapsulation of annatto seed oil (rich in geranylgeraniol) assisted by high intensity ultrasound using gum Arabic (GA) as stabilizing agent. We studied the effects of time (min) and ultrasonication power (W) over the emulsion characteristics. After forming microparticles from the best emulsion using freeze-drying (FD) and spray-drying (SD) techniques, we evaluated particle size distribution, moisture, water activity, surface oil, entrapment efficiency, encapsulation efficiency, geranylgeraniol retention, oxidative stability and kinetic release of geranylgeraniol, a biocompound with functional activities. The combined intensification of time and ultrasonication power reduced the superficial mean diameter (D₃₂) and polydispersity (PDI) of emulsions. Drying the continuous phase of the optimized emulsion (smallest D₃₂ = 0.69 ± 0.03 μm) using FD and SD formed microparticles with different morphological characteristics, Brouckere diameter (D₄₃), particle size distribution, moisture and water activity. SD process led to microparticles with the highest oil encapsulation efficiency (85.1 ± 0.1 wt.%) as a consequence of their lowest surface oil (SO). However, GA-FD microparticles presented the highest oil entrapment efficiency (97 ± 1 wt.%). Geranylgeraniol retention (80–86 wt.%) was similar for both drying techniques. GA-FD microparticles were more stable against oxidation through accelerated test Rancimat, even though presenting higher SO. This behavior is associated with the likely phase transition on the GA-SD matrix. The difference on the kinetic release of geranylgeraniol is linked to the difference on the particles morphology and particle size distribution.     

Influence of environmental stresses on the physicochemical stability of orange oil bilayer emulsions coated by lactoferrin–soybean soluble polysaccharides and lactoferrin–beet pectin

Based on layer-by-layer electrostatic deposition, orange oil bilayer emulsions stabilized with lactoferrin (LF)–soybean soluble polysaccharides (SSPS) and lactoferrin (LF)–beet pectin (BP) were prepared. The effect of environmental stresses (ionic strength, pH, freeze–thaw and light) on the physicochemical stability of primary and secondary emulsions was investigated. In the absence of anionic polysaccharides, orange oil emulsion was highly unstable and aggregated at pH 7–9 and NaCl of 0.1–0.5 M. The droplets in LF–SSPS coated emulsion were stable against aggregation at pH range of 3–10 and NaCl concentration less than 0.3 M, while the droplets in LF–BP coated emulsion were stable against aggregation at pH 4–9 and NaCl concentrations of 0–0.5 M. All the primary and secondary emulsions showed the instability after the freeze–thaw treatment and the stability could be improved in the presence of maltodextrin. During the light exposure (0.35 W/m², 45 °C) for 8 h, the bilayer emulsions could protect key volatile compounds (decanal, octanal and geranial) from the oxidation compared with the primary emulsions. These results suggested that the layer-by-layer electrostatic deposition could improve the stability of LF-coated emulsion to environmental stresses.     

Hepatoprotection using sweet orange peel and its bioactive compound,hesperidin, for CCl4-induced liver injury in vivo

The hepatoprotective effect of water extracts of sweet orange (Citrus sinensis) peel (WESP) and its biological compound, hesperidin (HD), on oxidative stress in vivo, were investigated. HD was the major compounds among the ten compounds identified using HPLC-DAD and HPLC-MS/MS analysis. Oral administration of WESP to rats at 10 and 100 mg/kg bw for 28 consecutive days before a single dose of CCl₄ (2 ml/kg bw) demonstrates a significant protective effect by lowering the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and by improving the histological architecture of the rat liver. WESP attenuated oxidative stress by increasing the content of hepatic glutathione (GSH), and by a dramatic increase in the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx). WESP induced a significant CYP2E1 activity, which suggests that WESP may be a substrate of CYP2E1. WESP at a dose of 1.0 mg/kg bw and HD at 0.1 mg/kg bw did not sustain the protective effect against oxidative stress, in vivo. This study demonstrated that citrus peel protects rat liver from CCl₄-induced injury by attenuating hepatic oxidative stress, which suggests that WESP can be used as a therapeutic antihepatotoxic agent for the treatment of hepatic injury.     

Factors affecting the rheological properties of a structured cellular solid used as a fat mimetic

The effects of water content, monoglyceride chain length and concentration, oil type, and the addition of oil-phase and water-phase additives on the elastic modulus and yield stress of a structured oil in water were evaluated. The goal was to increase the elastic modulus of the original emulsion from 8.42 × 10³ ± 11.3 Pa to 1.55 × 10⁶ ± 2.1 × 10⁵ Pa, and the yield stress from 112 ± 2.31 Pa to 835 ± 227 Pa. The addition of wax at greater than 10% (w/w), the use of palm oil or the gelation of the liquid oil phase with 5–7.5% rice bran wax, the use of C-18 saturated monoglyceride at 6%(w/w), and 4% (w/w) for C-22 saturated monoglyceride molecules were effective modifications capable of improving the mechanical behavior of the emulsion so that it can be used as a zero trans and reduced saturated fat laminating shortening substitute for puff pastry products.     

Physical stability of emulsion encapsulated in alginate microgel particles by the impinging aerosol technique

Emulsion filled alginate microgel particles can be applied as carrier systems for lipophilic actives in pharmaceutical and food formulations. In this study, the effects of oil concentration, emulsifier type and oil droplet size on the physical stability of emulsions encapsulated in calcium alginate microgel particles (20–80 μm) produced by a continuous impinging aerosol technique were studied. Oil emulsions emulsified by using either sodium caseinate (SCN) or Tween 80 were encapsulated at different oil concentrations (32.55, 66.66 and 76.68% w/w of total solids content). The emulsions were analysed before and after encapsulation for changes in emulsion size distribution during storage, and compared to unencapsulated emulsions. The size distribution of encapsulated fine emulsion (mean size ~ 0.20 μm) shifted to a larger size distribution range during encapsulation possibly due to the contraction effect of the microgel particles. Coarse emulsion droplets (mean size ~ 18 μm) underwent a size reduction during encapsulation due to the shearing effect of the atomizing nozzle. However, no further size changes in the encapsulated emulsion were detected over four weeks. The type of emulsifier used and emulsion concentration did not significantly affect the emulsion stability. The results suggest that the rigid gel matrix is an effective method for stabilising lipid emulsions and can be used as a carrier for functional ingredients.     

Antioxidant activity and effective compounds of immature calamondin peel

The antioxidant activity and the flavonoids of mature and immature calamondin (Citrus mitis Blanco) peel were investigated. The hot water extract of immature calamondin peel exhibited the highest oxygen radical absorbance capacity (ORAC), reducing power, and superoxide scavenging effect. 3′,5′-Di-C-β-glucopyranosylphloretin, naringin, hesperidin, nobiletin, and tangeretin are the five major flavonoids found in hot water extract with the levels of 6888 ± 522, 2333 ± 157, 1350 ± 94, 165 ± 13, and 8 ± 4 mg/100 g dry basis, respectively. The contents of nobiletin and tangeretin increased after ripening. The hot water extract of immature calamondin peel was fractionated using a semi-preparative HPLC. Fraction VI showed the highest ORAC value (28.02 ± 2.73 mmol Trolox equivalents (TE)/g fraction) and two compounds, naringin and hesperidin, were identified as the major active components attributed to the antioxidant activity. Fraction V contained 3′,5′-di-C-β-glucopyranosylphloretin, which revealed low ORAC value with 7.43 mmol TE/g fraction. However, it might also contribute to antioxidant activity in immature calamondin peel due to its greatest quantity.     

The increased viability of probiotic Lactobacillus salivarius NRRL B-30514 encapsulated in emulsions with multiple lipid-protein-pectin layers

Probiotics have demonstrated various health benefits but have poor stability to sustain food processing and storage conditions, as well as after ingestion. Biopolymer beads are commonly studied to encapsulate probiotic cells to improve their stability, but the millimeter-dimension of these beads may not meet the quality requirement of food products. The aim of this study was to enhance the viability of Lactobacillus salivarius NRRL B-30514 by encapsulation in emulsion droplets with multiple lipid-protein-pectin layers. Spray-dried L. salivarius was suspended in melted anhydrous milk fat that was then emulsified in a neutral aqueous phase with whey protein isolate or sodium caseinate to prepare primary solid/oil/water (S/O/W) emulsions. Subsequently, pectin was electrostatically deposited onto the droplet surface at pH 3.0 to form secondary emulsions. The encapsulation efficiency was up to 90%. After 20-day storage at 4 °C, the viable cell counts of bacteria in secondary emulsions at pH 3.0 and primary emulsions at 7.0 were 3 log higher than the respective free cell controls. After heating at 63 °C for 30 min, free L. salivarius was inactivated to be undetectable, while about 2.0 log CFU/mL was observed for primary (at pH 7.0) and secondary (at pH 3.0) emulsion treatments. Additionally, a 5 log-CFU/g-powder reduction was observed after spray drying free L. salivarius, while a 2 log CFU/g reduction was observed for emulsion treatments with capsules smaller than 20 μm. Furthermore, cross-linking the secondary emulsion with calcium enhanced the viability of L. salivarius after the simulated gastric and intestinal digestions. Therefore, the studied S/O/W emulsion systems may be used to improve the viability of probiotics during processing, storage, and gastrointestinal digestion.     

Emulsifying properties of lactose-amines in oil-in-water emulsions

Lactose-amines were synthesized with hexadecyl-amide and lactose via the Maillard reaction and their emulsion stabilization properties were investigated. Lactose-amines were synthesized using two different constant heating (4 and 8 h) and two different heating/cooling cycles (12 and 24 h). Each lactose-amine sample was used as an emulsifier in 20:80 ratio oil-in-water emulsions at four different concentrations (0.01%, 0.05%, 0.1%, and 1%). Emulsion stability was monitored by measuring the oil droplet sizes and the extent of destabilization via clarification over 5 days. At 1% concentrations, emulsions prepared with lactose-amines synthesized for 4, 12, and 24 h were as stable as the whey protein positive control emulsion. The 8 h lactose-amine sample resulted in a less stable emulsion. We assume the difference is related to the amount of heat this sample was exposed to during synthesis, with extensive heat leading to advanced Maillard products, which possessed reduced emulsification properties.     

Microencapsulation of walnut oil by spray drying: Effects of wall material and drying conditions on physicochemical properties of microcapsules

In this study, the effects of wall material formula and spray drying conditions on physicochemical properties of walnut oil microcapsules were investigated. Three different wall materials including skim milk powder (SMP), SMP + Tween 80, and SMP + maltodextrin were used for emulsion preparation. The prepared emulsions were analyzed for droplet size and stability. The emulsions were then dried in a pilot-scale spray dryer equipped with a two-fluid nozzle at different inlet drying air temperatures and feed atomization pressures in order to determine the optimal drying conditions for maximizing the microencapsulation efficiency. The microencapsulation efficiency, particle size distribution, sphericity, moisture content, bulk density, and morphology of produced microcapsules were also measured experimentally. In addition, the microcapsules with the highest microencapsulation efficiency obtained from each wall material were subjected to surface coverage of oil test using electron spectroscopy for chemical analysis (ESCA) after 60 days of storage at room temperature. The emulsion prepared using SMP and Tween 80 combination as wall material resulted in the highest microencapsulation efficiency (91.01%) at drying air temperature of 180 °C and feed atomization pressure of 3 bar. The lowest surface coverage of oil was also observed for microcapsules covered by SMP and Tween 80 combination. Scanning electron microscopy (SEM) observations showed almost no cracks or fissures on the surface of microcapsules produced using SMP and Tween 80 combination at the optimal drying condition.Industrial relevanceWalnut oil contains highly valuable constituents such as essential fatty acids, tocopherols, and phytosterols. However, a direct application of this functional oil in processed foods is problematic due to its low solubility and susceptibility to oxidation. These issues could be greatly overcome by using microencapsulation technology. Nowadays, this technology has received an increasing attention in food and pharmaceutical industries due to its unique features in protecting the functionality of ingredients. Spray drying technology is one of the most frequently used techniques for this aim. However, comprehensive studies need to be carried out in order to determine suitable operational conditions of spray drying system for improving physicochemical properties of finished powder.     

Aqueous extraction of virgin olive oil using industrial enzymes

In the present study, the effects of olive variety (Kroneiki, Iranian Native Oleaginous and Mission), enzyme type (Pectinex Ultra SP-L and Pectinase 1.6021) and concentration (zero, low and high concentration) on the yield, total polyphenols, turbidity, colour, acidity, peroxide value and iodine value of three enzyme-treated virgin olive oil were investigated. A 3 × 2 × 3 completely randomized experimental design (CRD) with replications was carried out. The enzyme concentration had a highly significant effect (p < 0.01) on the yield, colour, turbidity and total polyphenol level of oil, but there were not significant effects (p < 0.05) on acidity, peroxide value and iodine value. Colour and phenolic compounds content in the oils showed significant differences (p < 0.05) between 13.0–62.2% and 13.9–72.6%, respectively, as compared with control. Turbidity was reduced significantly (p < 0.01) 25.9–67.4%. On the basis of our results, the yield of oil was significantly (p < 0.01) increased (from 0.9% to 2.4%) by using processing aid. Pectinex Ultra SP-L was more effective than Pectinase 1.06021. In the case of applying Ultra pectinex SP-L, the additional income due to extra recovered oil will be 18.8 times as much production overhead.     

Effect of plant extracts on the oxidative stability of sunflower oil and emulsion

The antioxidative activities of six plant extracts (catnip, hyssop, lemon balm, oregano, sage and thyme) were evaluated in sunflower oil and its 20% oil-in-water emulsion in the dark at 60°C. The oxidation process was followed by measuring the formation of primary (conjugated diene hydroperoxides) and secondary (volatile compounds) oxidation products. Sage extracts (600 and 1200 ppm) effectively inhibited the formation of conjugated dienes and volatile compounds (hexanal and pentanal) in oil and emulsion and showed the highest antioxidative activity compared with 300 ppm BHT. Thyme and lemon balm extracts inhibited hexanal generation more than formation of conjugated dienes in both oil and emulsion. Oregano extract was more active in oil than in emulsion. Catnip and hyssop extracts (600 ppm) showed prooxidative action to sunflower oil at 60°C. These two extracts increased the formation of conjugated dienes compared with the control oil. In emulsions, catnip extract (600 ppm) was active and significantly inhibited the formation of conjugated dienes more than BHT (300 ppm) during additional incubation.     

Encapsulation of flaxseed oil within native and modified lentil protein-based microcapsules

The physical properties of lentil protein-based maltodextrin microcapsules with entrapped flaxseed oil was investigated using native (n-LPI) and pre-treated (heated, un-hydrolyzed (u-LPI); and heated, hydrolyzed (h-LPI)) lentil proteins and as a function of oil load (10, 20 and 30% of total solids). Specifically, the moisture, water activity, surface oil and entrapment efficiency (EE) were assessed, along with droplet size and emulsion morphology of all formulations. Moisture (< 6%) and water activity (< 0.2) of all capsules were characteristics of dried powder ingredients. Light microscopy imaging of the emulsions, revealed that the h-LPI had slightly larger oil droplets than the n-LPI and u-LPI, which both appeared similar. Findings were confirmed by light scattering, where droplet sizes were 6.7, 4.2 and 4.2 μm for the h-LPI, u-LPI and n-LPI stabilized emulsions, respectively. Overall capsules prepared from h-LPI showed significantly higher surface oil and lower EE than both the n-LPI and u-LPI materials. Furthermore, as the oil content increased, overall surface oil became higher and EE became lower. Based on testing, capsules prepared using n-LPI with 10% oil loading was found to have the lowest surface oil content (~ 3.7%) and highest EE (~ 62.8%) for all formulations, and was subjected to an oxidative storage stability test over a 30 d period vs. free oil. The encapsulation process proved to be effective at lowering the production of primary and secondary oxidative products than free oil.