Ferrous bisglycinate content and release in W1/O/W2 multiple emulsions stabilized by protein–polysaccharide complexes

Ferrous bisglycinate aqueous solution was entrapped in the inner phase (W₁) of water-in-oil-in-water (W₁/O/W₂) multiple emulsions. The primary ferrous bisglycinate aqueous solution-in-mineral oil (W₁/O) emulsion contained 15% (w/w) ferrous bisglycinate, had a dispersed phase mass fraction of 0.5, and was stabilized with a mixture of Grindsted PGPR 90:Panodan SDK (6:4 ratio) with a total emulsifiers concentration of 5% (w/w). This primary emulsion was re-emulsified in order to prepare W₁/O/W₂ multiple emulsions, with a dispersed mass fraction of 0.2, and stabilized using protein (whey protein concentrate (WPC)):polysaccharide (gum arabic (GA) or mesquite gum (MG) or low methoxyl pectin (LMP)) complexes (2:1 ratio) in the W₂ aqueous phase. The W₁/O/W₂ multiple emulsion stabilized with WPC:MG (5% w/w total biopolymers concentration) provided smaller droplet sizes (2.05 μm), lower rate of droplet coalescence (7.09 × 10⁻⁷ s⁻¹), better protection against ferrous bisglycinate oxidation (29.75% Fe³⁺) and slower rate of ferrous bisglycinate release from W₁ to W₂ (K_H = 0.69 mg mL⁻¹ min^−0.5 in the first 24 h and 0.07 mg mL⁻¹ min^−0.5 for the next 19 days of storage time). Better encapsulation efficiencies, enhanced protection against oxidation and slower release rates of ferrous bisglycinate were achieved as the molecular weight of the polysaccharide making up protein:polysaccharide complex was higher. Thus, the factor that probably affected most the overall functionality of multiple emulsions was the thickness of the complex adsorbed around the multiple emulsion oil droplets. These thicknesses determined indirectly by measuring the z-average diameter of the complexes, and that of the WPC:MG (529.4 nm) was the largest.     

“Influence of physicochemical properties of enzymatically modified starch gel on the encapsulation efficiency of W/O/W emulsion containing NaCl”

We investigated the molecular characteristics of 4-α-glucanotransferase (4αGTase)-modified rice starch (MRS) and corn starch (MCS) gels and the NaCl release properties depending on their mechanical properties. Also, encapsulation efficiency (EE) and oil globule size of water-in-oil-in-water (W/O/W) emulsions containing MRS or MCS in the inner aqueous phase (W₁) with NaCl as a model core material were measured after preparation and 14 days of storage. The characteristics of MRS and MCS were examined by analyzing amylose content, molecular fine structure, microstructure, and mechanical properties to better understand their associations with emulsion stability. At 20 % concentration, the gel strength of MCS (~10⁵ pa) was greater than that of MRS (~10³ pa) as MCS had higher apparent amylose content than MRS. The rate of NaCl release from the gel was highly correlated with the gel strength that depended on the type and concentration of the enzymatically-modified starch. As the gel strength increased, EE of freshly prepared and stored W/O/W emulsions increased. Osmotic swelling of NaCl-containing W/O/W was significantly reduced with the incorporation of the modified starch gels in W₁ phase. These results indicated that physicochemical properties of 4αGTase-modified starch gels in W/O/W emulsions largely affected the encapsulation efficiency and stability of the emulsions, which could be utilized to formulate W/O/W emulsions with improved stability and the potential for broader applications.     

Stability and release properties of double-emulsions stabilised by caseinate–dextran conjugates

The subject of the present paper was to investigate the possibility of stabilising water-in-oil-in-water emulsions (W/O/W) by using sodium caseinate (SC)–dextran (Dex) conjugates in order to influence the release of vitamin B₁₂ from the inner water phase (W₁) to the outer aqueous phase (W₂).To prepare the conjugate the SC was combined with Dex (M_r 250,000 or 500,000 g/mol) and incubated at 60 °C and a humidity of 79% for 8 h.The double emulsions, with encapsulated vitamin B₁₂, were prepared using a two-step emulsification technique. Whereas different amounts of polyglycerin polyricinoleate (PGPR, E476) were the hydrophobic emulsifier, the conjugate and the SC alone were used as the hydrophilic emulsifiers. The investigations comprised the determination of the particle size distribution of the W/O/W emulsion and measurement of the amount of vitamin B₁₂ migration from W₁- to the W₂-phase during the second stage of emulsion preparation and after heating or pH changing of emulsion.The water-containing oil droplets of the W/O/W emulsions were smaller and distributed more narrowly using SC–Dex conjugate as emulsifier instead of pure protein. Under acidic conditions, the conjugate-containing emulsions were more coalescence stable than the emulsions with SC, and the vitamin B₁₂ release from the inner W₁-phase was significantly decreased.     

Sodium caseinate–maltodextrin conjugate stabilized double emulsions: Encapsulation and stability

The potential food applications of water-in-oil-in-water (W₁/O/W₂) double emulsions are great, including the encapsulation of flavours or active ingredients. However, the stability of these emulsions restricts their applications in food systems. Sodium caseinate (NaCN)–maltodextrin (Md40 or Md100) conjugates were investigated for their potential to improve the stability of W₁/O/W₂ double emulsions compared to NaCN. NaCN–Md40 and NaCN–Md100 conjugates were prepared by a Maillard-type reaction by dry heat treatment of mixtures of NaCN–Md40 or NaCN–Md100 at 60 °C and 79% relative humidity for 4 days. Water-in-oil-in-water (W₁/O/W₂) double emulsions with NaCN, NaCN–Md40 or NaCN–Md100 as outer aqueous phase containing emulsifier were prepared using a two-step emulsification process. General emulsion stability was characterised by determining the droplet size distribution, viscosity characteristics and by confocal microscopy of the W₁/O/W₂ double emulsions on formation and after their storage under accelerated shelf life testing conditions at 45 °C for up to 7 days. Inner phase encapsulation and stability were characterised by monitoring the level of entrapped Vitamin B₁₂ in the inner aqueous phase on formation of the double emulsions and after storage at 45 °C for up to 7 days. Conjugate stabilized emulsions were more generally stable than NaCN stabilized emulsions. In comparison to NaCN stabilized emulsions, conjugate stabilized emulsions showed improved Vitamin B₁₂ encapsulation efficiency in the inner aqueous phase on emulsion formation and improved encapsulation stability following storage of the emulsions.     

Double emulsion (W/O/W) gel stabilised by polyglycerol polyricinoleate and calcium caseinate as mangiferin carrier: insights on formulation and stability properties

Mangiferin (MGF) is a phenolic compound isolated from mango, but its poor solubility significantly limits its use. In this study, MGF was embedded into the inner aqueous phase of W₁/O/W₂ emulsions. Firstly, the dissolution method of MGF was determined. MGF remained stable in solution with pH 13 at 30 min, and its solubility reached 10 mg mL⁻¹. When the pH of MGF solutions was adjusted from pH 13 to pH 6, MGF did not immediately crystallise, providing sufficient time to construct the MGF-loaded W₁/O/W₂ emulsions. Subsequently, the MGF-loaded W₁/O/W₂ emulsions were constructed using polyglycerol polyricinoleate (PGPR) and calcium caseinate (CAS). The formation and stability of the W₁/O/W₂ emulsions were investigated. The MGF-loaded W₁/O/W₂ emulsions stabilised with 1% PGPR and 1% – 3% CAS exhibited a low viscosity, limited loading capacity, and poor stability. Conversely, the MGF-loaded W₁/O/W₂ emulsions stabilised by 3%PGPR–3%CAS exhibited optimal loading capacity (encapsulation efficiency = 95.31% and loading efficiency = 0.91%) and stability, which was attributed to the fact that high viscosity and gel state retarded the migration of inner aqueous phase. These results indicated that the W₁/O/W₂ emulsions stabilised by PGPR and CAS may be a potential alternative for encapsulating mangiferin.     

Pancreatin-induced coalescence of oil-in-water emulsions in an in vitro duodenal model

The behaviour of cationic lactoferrin-stabilized and anionic β-lactoglobulin (β-lg)-stabilized oil-in-water emulsions (20.0% (w/w) soy oil, 1.0% (w/w) protein) in the presence of simulated intestinal fluid (SIF) containing physiological concentrations of pancreatin (0.0–10.0 mg mL^?1) and/or bile salts (0.0–25.0 mg mL^?1) at 37 °C, pH 7.5 and inorganic salts (39 mm K₂HPO₄, 150 mm NaCl and 30 mm CaCl₂) was investigated. Both emulsions showed a significant degree of coalescence and fatty acid release on mixing with SIF. Appreciably negative ζ-potential values (≥?50 mV) for both types of emulsion droplet at the highest pancreatin/bile salts concentration could be attributed to displacement of and/or binding to the interfacial proteins by bile salts, together with interfacial proteolysis by pancreatin, which enhanced the potential for lipase to act on the hydrophobic lipid core, thus generating free fatty acids and possibly mono- and/or diglycerides at the droplet surface.     

Formulation of monodisperse oil‐in‐water emulsions loaded with ergocalciferol and cholecalciferol by microchannel emulsification: insights of production characteristics and stability

Nutritional deficiencies of ergocalciferol (VD₂) and cholecalciferol (VD₃) cause skeletal deformations. The primary aim of this study was to encapsulate VD₂ and VD₃ in food‐grade oil‐in‐water (O/W) emulsions by using microchannel emulsification (MCE). Silicon asymmetric straight‐through microchannel (MC) array consisting of 10 313 channels, each having an 11 × 104 μm microslot connected to a 10 μm circular microholes. 1% (w/w) sodium cholate or Tween 20 in water was used as the continuous phase, while 0.5% (w/w) of each VD₂ and VD₃ in different oils served as the dispersed phase. Monodisperse O/W emulsions with Sauter mean diameters of 28 to 32 μm and relative span factor widths below 0.3 were formulated via an asymmetric straight‐through MC array under appropriate operating conditions. The monodisperse O/W emulsions stabilised with Tween 20 remained stable for >30 days with encapsulation efficiencies (EEs) of VD₂ and VD₃ of above 70% at 4 and 25 °C. In contrast, those stabilised with sodium cholate had stability of >30 days with their EEs of over 70% only at 25 °C.     

The Effect of Sodium Carboxymethylcellulose on the Stability and Bioaccessibility of Anthocyanin Water-in-Oil-in-Water Emulsions

Water-in-oil-in-water (W₁/O/W₂) emulsions provide protective encapsulation to plant bioactive compounds in food matrix and under gastrointestinal conditions. However, the stability of the emulsions during the storage is crucial for their use in the food industry. Hence, the aim of this study was to enhance the stability and bioaccessibility of W₁/O/W₂ emulsions containing anthocyanins with the use of sodium carboxymethylcellulose (CMCNa). The emulsions were prepared by ultrasound technology, adding polyglycerol polyricinoleate (PGPR) in the inner aqueous phase of emulsions, and lecithin and Tween 20 in the outer aqueous phase. The systems were physicochemical characterized over the time and their behavior under simulated gastrointestinal conditions was investigated. Our results showed high encapsulation efficiencies above 90% and an increase in bioaccessibility with the use of CMCNa. Moreover, the polymer addition slowed down the free fatty acid release and increased the oil digestibility of lecithin-stabilized emulsions. These latter emulsions presented the highest bioaccessibility (31.08?±?1.73%), the more negative values of ζ-potential and no variations on the particle size and the backscattering profile over the time, thus being the most stable emulsions. These results provide useful information for the design of anthocyanin emulsion-based delivery systems to guarantee their functionality in food matrices as well as through the gastrointestinal tract.     

Fabrication and characterization of filled hydrogel particles based on sequential segregative and aggregative biopolymer phase separation

In this study, filled hydrogel particles were created based on the ability of proteins and ionic polysaccharides to phase separate through both aggregative (complexation) and segregative (incompatibility) mechanisms. At pH 7, a mixture of 3% (w/w) high-methoxy pectin and 3% (w/w) sodium caseinate phase separated through a segregative mechanism. Following centrifugation, the phase separated system consisted of an upper pectin-rich phase and a lower casein-rich phase. Casein-coated lipid droplets added to the phase separated pectin/caseinate system partitioning into the lower casein-rich phase. This was attributed to a reduction in the unfavorable osmotic stress in this phase associated with biopolymer depletion. When shear was applied this system formed an oil-in-water-in-water (O/W₁/W₂) emulsion consisting of oil droplets (O) contained within a casein-rich watery dispersed phase (W₁) suspended in a pectin-rich watery continuous phase (W₂). Acidification of the O/W₁/W₂ system from pH 7–5 promoted adsorption of pectin around the casein-rich W₁ droplets, resulting in the formation of filled hydrogel particles (d = 3–4 μm) that remained stable to aggregation or dissociation when stored for 24 h at ambient temperature. These particles may be useful as encapsulation and delivery systems for lipophilic components in the food, cosmetics and pharmaceutical industries.     

Water soluble inner aqueous phase markers as indicators of the encapsulation properties of water-in-oil-in-water emulsions stabilized with sodium caseinate

The aim of this study was to evaluate the suitability of Methylene Blue (MB) and Vitamin B₁₂ (Vit-B₁₂) as water soluble inner aqueous phase (W₁) markers for measuring the encapsulation efficiency and stability of water-in-oil-in-water (W₁/O/W₂) double emulsions stabilized by sodium caseinate (NaCN). The encapsulation efficiency and stability were determined by centrifugation of the double emulsion to separate the cream phase (W₁/O) and the outer aqueous phase (W₂) and measuring the concentration of marker in W₂ by absorbance spectrophotometry. To validate this method the marker concentration measurable and the stability of the marker in W₂ were measured. Both markers could be accurately measured in W₂ and there was no change in the concentration of marker on storage of a W₂ solution for 7 days at 45 °C. The recovery yields of MB and Vit-B₁₂ in the recovered W₂ of an oil-in-water (O/W₂) emulsion, determined using the procedure normally used for measuring encapsulation efficiency and stability, were 78% and 99%, respectively, and 52 and 100%, respectively. Double emulsions had encapsulation efficiency of 61.9 ± 21.4% and 16.6 ± 1.1% and encapsulation stability of 62.0 ± 22.6% and 10.7 ± 0.7% for MB and Vit-B₁₂, respectively. Recovery yield and encapsulation efficiency/stability data for MB indicate that it is not a suitable marker for measuring the encapsulation properties of NaCN stabilized double emulsions while similar data for Vit-B₁₂ indicate that it is a suitable marker for studying the encapsulation properties of double emulsions stabilized with NaCN. Methods used in other studies to measure encapsulation properties of double emulsions are discussed in light of the results obtained in this study.     

Impact of amylose from maize starch on the microstructure,rheology and lipolysis of W/O emulsions during simulated semi-dynamic gastrointestinal digestion

This study aims to examine the microstructure, rheology and lipolysis of water-in-oil (W/O) emulsions (40 wt.%) prepared with or without (Control) the addition of normal (NAM) and high amylose (HAM) maize starch during simulated digestion in a semi-dynamic gastrointestinal tract (GIT) model. Microstructural examinations showed modification in initial W/O emulsion droplets to multiple W₁/O/W₂ droplets during in vitro digestion. This is in line with the rheological results, where the shear viscosity and moduli in the oral phase were remarkably reduced after entering the intestinal phase. In comparison to control and NAM emulsions, HAM emulsions showed a more compact and continuous network structure and greater viscosity and elastic modulus throughout GIT digestion. These results support lipolysis, where fewer free fatty acids were released in the HAM emulsion (70%) than in the control (86%) and NAM (78%) emulsions. This work has provided an in-depth understanding of the digestion of W/O emulsions as influenced by amylose content, which is meaningful for the development of low-fat products with reduced lipid digestibility.     

Preparation and impact of multiple (water-in-oil-in-water) emulsions in meat systems

The aim of this paper was to prepare and characterise multiple emulsions and assess their utility as pork backfat replacers in meat gel/emulsion model systems. In order to improve the fat content (in quantitative and qualitative terms) pork backfat was replaced by a water-in-oil-in-water emulsion (W₁/O/W₂) prepared with olive oil (as lipid phase), polyglycerol ester of polyricinoleic acid (PGPR) as a lipophilic emulsifier, and sodium caseinate (SC) and whey protein concentrate (WP) as hydrophilic emulsifiers. The emulsion properties (particle size and distribution, stability, microstructure) and meat model system characteristics (composition, texture, fat and water binding properties, and colour) of the W₁/O/W₂, as affected by reformulation, were evaluated. Multiple emulsions showed a well-defined monomodal distribution. Freshly prepared multiple emulsions showed good thermal stability (better using SC) with no creaming. The meat systems had good water and fat binding properties irrespective of formulation. The effect on texture by replacement of pork backfat by W₁/O/W₂ emulsions generally depends on the type of double emulsion (associated with the hydrophilic emulsifier used in its formulation) and the fat level in the meat system.     

On the selection of relevant environmental factors to predict microbial dynamics in solidified media

Several studies have shown that food structure causes slower growth rates and narrower growth boundaries of bacteria compared to laboratory media. In predictive microbiology, both a_w or corresponding solute concentration (mainly NaCl) have been used as a growth influencing factor for kinetic models or growth/no growth interface models. The majority of these models have been based on data generated in liquid broth media with NaCl as the predominant a_w influencing solute. However, in complex food systems, other a_w influencing components might be present, next to NaCl. In this study, the growth rate of Salmonella typhimurium was studied in the growth region and the growth/no growth response was tested in Tryptic Soy Broth at 20 °C at varying gelatin concentration (0, 10, 50 g L⁻¹ gelatin), pH (3.25–5.5) and water activity (a_w) (0.929–0.996). From the viewpoint of water activity, the results suggest that NaCl is the main a_w affecting compound. However, gelatin seemed to have an effect on medium a_w too. Moreover, there is also an interaction effect between NaCl and gelatin. From the microbial viewpoint, the results confirmed that the a_w decreasing effect of gelatin is less harmful to cells than the effect of Na⁺ ions. The unexpected shift of the growth/no growth interface to more severe conditions when going from a liquid medium to a medium with 10 g L⁻¹ gelatin is more pronounced when formulating the models in terms of a_w than in terms of NaCl concentrations. At 50 g L⁻¹ gelatin, the model factored with NaCl concentration shifts to milder conditions (concordant to literature results) while the model with a_w indicates a further shift to more severe conditions, which is due to the water activity lowering effect of gelatin and the interaction between gelatin and NaCl. The results suggest that solute concentration should be used instead of a_w, both for kinetic models in the growth region and for growth/no growth interface models, if the transferability of models to solid foods is to be increased.     

Structural and textural characteristics of reduced-fat cheese-like products made from W1/O/W2 emulsions and skim milk

The chemical composition, yield, structural arrangement, instrumental textural characteristics, and preference sensory evaluation of reduced-fat cheese-like products manufactured from skim milk and different water-in-oil-in-water (W₁/O/W₂) emulsions were determined. A full-fat white fresh cheese (WFC) was prepared from milk containing 27 g of milk-fat L⁻¹, and five reduced-fat white fresh cheese-like products (EC) were made from skim milk added with 25 g of multiple emulsions L⁻¹ containing canola oil and stabilized/emulsified by amidated low-methoxyl pectin (LMP), carboxymethylcellulose (CMC), gum Arabic (GA), and blends of GA-CMC or GA-LMP. The chemical composition, yield, structural arrangement and texture of the cheese-like products were affected by the biopolymers used as emulsifying/stabilizing agents of the multiple emulsions. CMC produced an EC with similar textural behaviour than the WFC cheese. GA contributed to a higher yield and fat content in the EC cheese in comparison with CMC and LMP cheese. GA and LMP contributed to increased values of hardness and chewiness of the EC cheese. The cheese made with multiple emulsions incorporating GA and LMP emulated best the textural characteristics of the WFC cheese. All of the EC cheese showed marked differences in microstructure.     

Reduced-fat white fresh cheese-like products obtained from W1/O/W2 multiple emulsions: Viscoelastic and high-resolution image analyses

This paper focuses on the study of the rheological and structural changes of reduced fat cheeses (EC) obtained by substituting milk-fat by multiple emulsions (W₁/O/W₂) stabilized with different hydrocolloids in comparison to a full-fat white fresh cheese (WFC). Amidated low-methoxyl pectin, carboxymethylcellulose (CMC), gum Arabic (GA), and blends of these hydrocolloids were used as emulsion stabilizing agents. Cheeses storage (G′) and loss (G″) moduli as a function of strain % were determined and the ratio of tan δ in the non-lineal viscoelastic region (tan δ_B) to that in the lineal viscoelastic region (tan δ_A) was obtained. The EC cheeses made from W₁/O/W₂ emulsions with GA (EC_GA) and CMC (EC_CMC) exhibited non-significantly different tan δ_B/tan δ_A ratio values from that of WFC cheese. Scanning electron micrographs (SEM) showed that all the cheeses exhibited different surface microstructure. Detrended fluctuation analysis (DFA) of SEM micrographs indicated that all cheeses structure displayed a hierarchical configuration, from well-ordered particles in the small scale range to randomly dispersed particles in the high scale range. The EC_GA and EC_CMC cheeses also showed similar particle distribution over the particle size range of 20–60 μm to that of the WFC cheese.     

Emulsifying characteristics of commercial canola protein–hydrocolloid systems

Emulsifying properties of commercial canola protein isolate (CPI)–hydrocolloid-stabilized emulsions were evaluated under varied conditions (CPI, salt and hydrocolloid concentrations; pH, denaturants). Emulsifying activity index (EAI) and emulsion stability (ES) were determined by turbidimetric testing. The results showed that under complexing conditions (at pH 6), the addition of 1% (w/v) κ-carrageenan (κ-CAR) increased the EAI of CPI-stabilized emulsions from 162 to 201 m²/g and ES from 68% to 95%. Under conditions promoting incompatibility (at pH 10), the use of 1% (w/v) guar gum increased the EAI of CPI-stabilized emulsions from 68 to 177 m²/g and ES from 66% to 100%. The lower EAI and ES values observed in CPI–hydrocolloid-stabilized emulsions treated with sodium salts and denaturants support the involvement of hydrophobic interactions, hydrogen bonds and disulfide linkages in the emulsification of these systems. Interfacial properties of CPI–hydrocolloid mixtures were improved by electrostatic complexing and incompatibility, making these systems suitable for stabilizing food emulsions.     

Comparison of properties of oil-in-water emulsions stabilized by coconut cream proteins with those stabilized by whey protein isolate

Coconut cream protein (CCP) fractions were isolated from coconuts using two different isolation procedures: isoelectric precipitation (CCP1-fraction) and freeze–thaw treatment (CCP2-fraction). The ability of these protein fractions to form and stabilize oil-in-water emulsions was compared with that of whey protein isolate (WPI). Protein solubility was a minimum at ∼pH 4, 4.5 and 5 for CCP1, CCP2, and WPI, respectively, and decreased with increasing salt concentration (0–200 mM NaCl) for the coconut proteins. All of the proteins studied were surface active, but WPI was more surface active than the two coconut cream proteins. The two coconut cream proteins were used to prepare 10 wt% corn oil-in-water emulsions (pH 6.2, 5 mM phosphate buffer). CCP2 emulsions had smaller mean droplet diameters (d₃₂ ≈ 2 μm) than CCP1 emulsions (d₃₂ ≈ 5 μm). Corn oil-in-water emulsions (10 wt%) stabilized by 0.2 wt% CCP2 and WPI were prepared with different pH values (3–8), salt concentrations (0–500 mM NaCl) and thermal treatments (50–90 °C for 30 min). Considerable droplet flocculation occurred in the emulsions near the isoelectric point of the proteins: CCP2 (pH ∼ 4.3); WPI (pH ∼ 4.8). Emulsions with monomodal particle size distributions, small mean droplet diameters, and good creaming stability could be produced at pH 7 for WPI, but CCP2 produced bimodal distributions at this pH. The CCP2 and WPI emulsions remained relatively stable to droplet aggregation and creaming at NaCl concentrations ⩽50 and ⩽100 mM, respectively. In the absence of salt, both CCP2 and WPI emulsions were quite stable to thermal treatments (50–90 °C for 30 min).     

Efficacy of diatomaceous earths and their low-dose combinations with spinosad or deltamethrin against three beetle pests of stored-maize

A key element in postharvest IPM is the reduction of chemical residues in food through the use of reduced dosages of less toxic grain protectants. Two laboratory experiments were conducted: Experiment I determined the efficacies of straight diatomaceous earths (DEs) – “Chemutsi” (African raw DE), MN51 (new formulation) and Protect-It^® (enhanced DE), and two new food grade DE-based formulations (A2 and A3) against adult Prostephanus truncatus (Horn), Sitophilus zeamais (Motschulsky) and Tribolium castaneum (Herbst) admixed with shelled maize. In Experiment II, Chemutsi and Protect-It^® were further tested in varying combinations with low-dose deltamethrin and spinosad. At 21 days post-exposure, MN51 800 ppm and 1000 ppm, Chemutsi 1000 ppm, Protect-It^® 600 ppm and food grade A3 150 ppm caused S. zeamais mortalities that were not significantly different from the positive control (Protect-It^® 1000 ppm). However, after the same exposure period, all the straight DEs (applied at ≤ 1000 ppm) and the DE-based food grade formulations were not effective on P. truncatus and T. castaneum. In low dose combinations, 7 day mortalities showed high S. zeamais susceptibility to both DE-spinosad and DE-deltamethrin while P. truncatus was more susceptible only to DE-spinosad and T. castaneum to Protect-It^®-deltamethrin only. At 21 days, all DE-spinosad and DE-deltamethrin treatments were effective and not significantly different from the commercial grain protectant (fenitrothion 1.0% w/w (10000 ppm) + deltamethrin 0.13% w/w (130 ppm)) on all test species. DE-spinosad and DE-deltamethrin combinations significantly suppressed (P < 0.001) F₁ progeny for the three test species whereas straight DEs and DE-based food grade formulations did not. Our results showed that at half the label rates or lower, DE-spinosad and DE-deltamethrin combinations were effective alternative grain protectants that are safer and possibly cheaper. We also give the first report on the effectiveness of Chemutsi in combination with spinosad or deltamethrin on maize grain.     

Potential of bagasse obtained using hydrothermal liquefaction pre-treatment as a natural emulsifier

Bagasse, a by-product from raw sugar factories, is conventionally burned for energy production. In this study, bagasse extracts from hydrothermal liquefaction (HTL) treatment (160 °C, 1 MPa and 30 min) with a carbohydrate content of 510.3 mg g⁻¹ and 0.5 mg g⁻¹ of total phenols were applied as emulsifiers in oil-in-water (O/W) emulsions. Bagasse extracts from HTL (0.5–4 wt%) lowered the interfacial tension between oil–water interphase from 19.8 to 14.0 mN m⁻¹, owing possibly to the surface-active hydrophilic carbohydrate-hydrophobic lignin complexes in the extracts (lignin content: 7.1% w/w). Emulsions stabilised by bagasse extracts from HTL with average droplet size, d_av of 0.79 μm were comparable with gum arabic (GA), d_av of 2.24 μm after 11 days at 25 °C. Bagasse extracts containing biopolymers have the potential for industrial applications involving emulsion systems; therefore, HTL treatment of bagasse without any solvents can be regarded as an effective tool for producing natural emulsifiers.     

Stabilization of acidic soy protein-based dispersions and emulsions by soy soluble polysaccharides

Soy soluble polysaccharides (SSPS) are shown to prevent destabilization of soy protein isolate (SPI) dispersions and SPI-based oil-in-water (O/W) emulsions under acidic conditions. Addition of SSPS above a critical concentration (0.25 wt%) increased the stability of 0.50 wt% SPI dispersions against aggregation and phase separation under conditions where SPI would normally precipitate (near its isoelectric point). Though SSPS neutralized SPI surface charge via electrostatic interaction, there was increased stability against aggregation due to steric repulsion. At acidic pH, addition of 1 wt% NaCl electrostatically screened protein–polysaccharide complexation which led to SPI precipitation and sedimentation. However, the order of salt addition had a significant impact on charge screening, with salt added before pH adjustment reducing SPI–SSPS complexation whereas it had less effect when added afterwards. Salt penetration efficacy diminished with decreasing pH. O/W emulsions (5 wt% oil) prepared with 0.50 wt% SPI destabilized at pH 4–5 due to protein aggregation, but addition of ≥0.25 wt% SSPS improved emulsion stability by inhibiting protein–protein interactions thus limiting increases in oil droplet diameter over time. Overall, both dispersion and emulsion stability greatly depended on pH, ionic strength and SSPS concentration. These results demonstrated that SSPS could effectively stabilize acidic SPI dispersions and that SPI–SSPS interactions may be used as a tool to improve the kinetic stability of SPI-based O/W emulsions.