Nanodispersing thymol in whey protein isolate-maltodextrin conjugate capsules produced using the emulsion–evaporation technique

This work presents simple processes to prepare transparent aqueous dispersions of thymol, a lipophilic antimicrobial compound. The emulsion–evaporation technique involved the preparation of capsules by spray-drying oil-in-water emulsions containing thymol dissolved in hexane emulsified using conjugates of whey protein isolate and maltodextrin. Hydration of spray-dried capsules resulted in transparent and heat stable nanodispersions containing thymol at concentrations well above its solubility limit, even at pH around the isoelectric points of whey proteins. The efficiency of encapsulation and the heat-stability of nanodispersions were affected by the emulsion composition. An encapsulation efficiency of 51.4% was obtained for one sample that corresponded to dispersions, adjusted to pH 3.0–7.0, with mean diameters of <90 nm after heating at 80 °C for 15 min. The present study demonstrates a promising technology to produce nanoscale systems for delivering lipophilic components in aqueous foods such as clear beverages.     

Effect of sucrose fatty acid esters on the particle characteristics and flow properties of phytosterol nanodispersions

The effect of four different types of sucrose fatty acid esters as nonionic emulsifiers on the physicochemical properties of water-soluble phytosterol nanodispersions was investigated. In general, the mean particle sizes of the prepared phytosterol nanodispersions ranged from 2.8 to 259.9 nm. The phytosterol content in the final prepared nanodispersions ranged from 230.4 to 504.6 mg/l. All of the prepared phytosterol nanodispersions exhibited pseudoplastic flow behavior, with low yield stress ranging from 0.630 to 9.183 mPa and a low consistency coefficient of 0.608-88.710 mPas. Less than 1.5 μl of hexane residues per liter of prepared nanodispersions was found in the prepared phytosterol nanodispersions. Transmission electron microscopy (TEM) demonstrated that the prepared phytosterol nanoparticles were spherical in shape. In general, the sucrose fatty acid esters P-1570, L-1695 and S-1570 are appropriate for use in the preparation of phytosterol nanoparticles with small mean particle size at monomodal distribution with high clarity in appearance.     

Effect of processing conditions on physicochemical properties of astaxanthin nanodispersions

A top-down approach based on an emulsification–evaporation technique was used to prepare nanodispersions of astaxanthin. Response-surface methodology was employed to investigate the effect of the main processing conditions, namely, the applied pressure (20–90 MPa), number of cycles (0–4) and evaporation temperature (16–66 °C), on the average particle size, polydispersity index and astaxanthin concentration of the nanodispersions. Second-order polynomial regression models expressing the astaxanthin nanodispersion properties as functions of the main processing variables were significantly (p < 0.05) fitted, with high coefficient-of-determination values (R² > 0.90). A multiple-optimisation procedure showed that the optimum conditions of pressure, number of cycles of homogenization and evaporation temperature, were 50 MPa, two cycles and 47 °C, respectively. A statistical assessment showed insignificant (p > 0.05) differences between experimental and predicted values, thus verifying the adequacy of the final reduced models fitted for explaining the variation of emulsion properties, as a function of homogenization and evaporation conditions.     

Effect of processing conditions on physicochemical properties of sodium caseinate-stabilized astaxanthin nanodispersions

The aim of the present study was to investigate the preparation of sodium caseinate-stabilized astaxanthin nanodispersions as potential active ingredients for food formulations in order to optimize processing conditions. Nanodispersions containing astaxanthin were prepared by an emulsification-evaporation processing technique. The influence of the processing conditions, namely, the pressure of the high-pressure homogenizer (20-90 MPa), the number of passes through the homogenizer (0-4) and the evaporation temperature (16-66 °C) on the physicochemical properties of the prepared astaxanthin nanodispersions were evaluated using a three-factor central composite design. Average particle size, polydispersity index (PDI) and astaxanthin loss in the prepared nanodispersions were considered as response variables. The multiple-response optimization predicted that using three passes through the high-pressure homogenizer at 30 MPa for the preparation of the astaxanthin nanoemulsion and then removing the organic phase (solvent) from the system by evaporation at 25 °C provided astaxanthin nanodispersions with optimum physicochemical properties.     

β-Carotene nanodispersions: preparation,characterization and stability evaluation

The aim of the present study was to investigate the preparation of β-carotene nanodispersions as potential active ingredients for food formulations. Nanodispersions containing β-carotene were obtained by a process based on an emulsification–evaporation technique. The preparation method consisted of emulsifying an organic solution of β-carotene in an aqueous solution containing emulsifier using two different homogenizers (a conventional homogenizer and a microfluidizer), followed by direct solvent evaporation under reduced pressure. The influence of different homogenizing conditions (pressure and cycle) and two organic/aqueous phase ratios on particle size parameters and content of β-carotene was investigated. In addition, the stability of β-carotene nanodispersions was carried out at a storage temperature of 4 °C. The particle size distribution of β-carotene in nanodispersions was demonstrated with a laser diffraction particle size analyzer and the retention of β-carotene in the prepared nanodispersions was studied by high-pressure liquid chromatography. In general, homogenization pressure and cycle had significant (P < 0.05) effects on various particle size parameters. A volume-weighted mean diameter (D_4,3) of β-carotene nanoparticles, ranging from 60 to 140 nm, was observed in this study.     

Proteolysis of ultra-high pressure homogenised treated milk during refrigerated storage

Plasmin residual activity and its relation to proteolysis of milk subjected to ultra-high pressure homogenisation (UHPH; 200–300 MPa, inlet temperature = 30 °C and 40 °C) and to a high-pasteurisation treatment (90 °C, 15 s) were studied during refrigerated storage. Proteolysis was examined by capillary electrophoresis, HPLC peptide profiles, pH 4.6-soluble nitrogen and free amino acids. Inactivation of plasmin increased as homogenisation pressure did. Extensive proteolysis, was observed in 200 MPa 40 °C milk, due to its higher native and microbial enzyme contents, compared with the other samples. In general, hydrolysis of β-casein, hydrophobic peptide and pH 4.6-soluble nitrogen levels increased with higher residual plasmin activity, while hydrophilic peptides were not affected by the different treatments applied. β-Lactoglobulin was denatured to a greater extent by thermal treatment than by UHPH treatments. This study provides further insight into how UHPH treatments influence milk properties.     

Esterification of insoluble fibres using high-pressure homogenisation and their potential vitamin carrying and releasing abilities

The esterification of carambola (starfruit) insoluble fibre (IF) and cellulose using high-pressure homogenisation without chemical catalyst was carried out as well as the evaluation of vitamin carrying and releasing abilities of the esterified fibres. Fourier transform infrared spectroscopic analyses showed that these fibres underwent structural changes and were esterified with lactic acid via a simple and fast process of high-pressure homogenisation. In vitro studies showed that the esterified fibres were capable of carrying vitamin E (∼11.2 mg g⁻¹ composite) and releasing nutrient slowly. In vivo studies further demonstrated that feeding the esterified carambola IF-vitamin composite could help maintain plasma vitamin E at relatively higher concentrations (∼1.7- to 3.8-fold of the initial value) for better utilisation for at least 5 h. The results suggested that the esterified insoluble fibres, especially the esterified carambola IF, could be exploited as potential nutrient carriers in functional food applications and slow-release formulations.     

High-pressure-homogenised cream liqueurs: Emulsification and stabilization efficiency

Recent progress in high-pressure technology has led to new opportunities for homogenisation processes. In this study, a high-pressure homogeniser and a standard radial diffuser homogeniser (Gaulin-type) were evaluated and compared in terms of their efficiency in model cream liqueur homogenisation and stabilization. Cream liqueurs with finely-dispersed droplets were produced on single-pass homogenisation using the high-pressure homogeniser. However, an increase in the homogenisation intensity above optimal conditions increased the mean fat droplet diameter. The standard radial diffuser homogeniser required multiple homogenisation passes to produce a stable cream liqueur. High-pressure homogenisation markedly increased cream liqueur temperature, due to pressure build-up and shear effects associated with conversion of kinetic energy into heat. Cream liqueurs with small mean fat droplet diameters, homogenised using the high-pressure homogeniser, displayed a slower rate of increase in droplet diameter and in viscosity during storage at 45 °C than those produced using a low pressure homogenisation process.     

Characteristics of submicron emulsions prepared by ultra-high pressure homogenisation: Effect of chilled or frozen storage

Model O/W pre-emulsions at an initial temperature of 24 °C and pH 6.3, and containing (w/w) 4.3% whey proteins plus 15, 30 or 45% peanut oil were processed using a ∼15 L/h homogeniser with a high pressure (HP) valve immediately followed by cooling heat exchangers. The effect of ultra-high pressure homogenisation (UHPH) between 100 and 300 MPa (P₁) or of recycling (1–3 homogenisation passes) at 200 MPa was investigated on the droplet size distribution, size indices and viscosity. Fluid temperatures were measured at the inlet (T₁) and outlet (T₂) of the HP-valve, and after immediate cooling downstream of the HP-valve (T₃) as they varied throughout UHPH. Short-life heating phenomena and mechanical energy involved in droplet processing were clearly influenced by emulsion composition. Oil droplet diameters decreased when (P₁) increased from 100 to 300 MPa leading to submicron droplets at ≥200 MPa. Monomodal distributions with droplets well below 0.3 μm were obtained after recycling at 200 MPa for the three oil contents, with a peak at 138 nm (distribution in volume) or 60–70 nm (in number frequency). The emulsion behaviour varied from fluid (and quite Newtonian) to thick (and shear thinning) depending on the droplet size reduction and the oil volume fraction. Emulsions displayed an excellent stability vs. creaming and coalescence after 9 d storage at 5 °C. Freezing followed by 13 d storage at −24 °C then thawing, induced an increase in particle sizes depending both on the oil volume fraction and (P₁). After UHPH at 200–225 MPa (±recycling), the freezing/thawing process maintained most of oil droplet size below 1 μm at 15% (w/w) oil, and induced mainly oil droplet aggregation through SDS-labile interactions at higher oil contents.     

Effects of genetic variability and planting location on the phytosterol content and composition in soybean seeds

Phytosterols present in soybean seeds have specific physiological activities related to serum cholesterol reduction. Therefore, soybean seeds containing high levels of phytosterols are required for soybean products as functional foods. However, little is known about effects of genetic variability and planting location on the phytosterol content and composition in soybean seeds. In this study, we analyzed phytosterol composition of 510 germplasm accessions of cultivated soybean seeds by gas liquid chromatography (GLC) as well as oil content. Phytosterol contents were in the range of 202 and 843 μg/g seed, and they depended on varieties of soybean seeds, but there was no significant difference between the phytosterol content in Japanese and non-Japanese seeds. The phytosterol content was higher in high oil soybean seeds. β-Sitosterol was the major phytosterol (43–67%) in soybean seeds, followed by campesterol (17–34%) and stigmasterol (10–30%). The phytosterol proportions were almost the same in all soybean seeds and it was not influenced by genetic variability and planting location.