Modelling of drying and rehydration of carrots using Peleg’s model

The drying and rehydration process of conventionally and organically cultivated carrots was studied and the resulting data were fitted to the Pelegs model. Carrots were fluid-bed and halogen dried and after that soaked in water at room temperature. The Pelegs model gave a good prediction of water removal and water uptake in all experiments (R>0,994). During the drying process the Pelegs rate constant (K₁) was affected by temperature. K₁ values decreased with the increase of the drying temperature. This relation was linear for fluid-bed drying and exponential for halogen drying, which implied a higher impact of the drying temperature on the dehydration kinetics during halogen drying. The lower K₁ values for fluid-bed drying suggested higher initial drying rates in comparison with halogen drying at all drying temperatures. The temperature dependence of 1/K₁ followed an Arrhenius-type relationship. Both Pelegs rehydration constants (K₁ and K₂) increased with the increase of the drying temperature. This implied regular decrease of initial rehydration rate and water uptake with the increase of the drying temperature.     

Nanoemulsions of β-carotene using a high-energy emulsification-evaporation technique

Nanoemulsions of β-carotene were prepared using a high-energy emulsification-evaporation technique based on a 2³ level factorial design. Results show that it is possible to obtain dispersions at a nanoscale range. Process parameters such as time and shear rate of homogenization affected significantly particle size distribution in terms of volume-weighted mean diameter and surface-weighted mean diameter. The obtained nanoemulsions presented a volume-surface diameter ranging from 9 to 280 nm immediately after the production of particles, displaying in all cases a monomodal size distribution. Those nanoemulsions showed a good physical stability during 21 days storage. The stability was evaluated by the maintenance of size distribution. However, β-carotene retention inside the micelles and color were affected by storage. Processing conditions also influenced storage stability.     

Stabilization of emulsions and foams using barley β-glucan

Barley β-glucan (BBG) is receiving increasing attention as a food hydrocolloid. Stability of foams and emulsions was assessed using whey protein concentrate (WPC) as an emulsifier and foaming agent, and BBG gum extracted at pilot plant or laboratory scale as a stabilizer. WPC had a significant lowering effect (P⩽0.05) on surface tension of water and water–oil interfacial tension, while the effect of β-glucan was time dependent. Differential scanning calorimetry (DSC) showed that BBG formed a gelled network, responsible for stabilizing, that melts at 58–62°C. Reversible gels of BBG melt around 63°C. Emulsion (50% o/w) droplet size decreased several fold when prepared with BBG gum and phase separation was substantially decreased. Foam volume and 50% drainage were significantly (P⩽0.05) improved upon addition of β-glucan. Sugar significantly enhanced foam stability only when used together with β-glucan. BBG shows potential as a stabilizer in foam- and emulsion-type food products.     

Optimization of β-casein stabilized nanoemulsions using experimental mixture design

The objective of this study was to determine the effect of changing viscosity and glass transition temperature in the continuous phase of nanoemulsion systems on subsequent stability. Formulations comprising of β-casein (2.5%, 5%, 7.5%, and 10% w/w), lactose (0% to 20% w/w), and trehalose (0% to 20% w/w) were generated from Design of Experiments (DOE) software and tested for glass transition temperature and onset of ice-melting temperature in maximally freeze-concentrated state (T(g) ' & T(m) '), and viscosity (μ). Increasing β-casein content resulted in significant (P < 0.0001) increases in viscosity and T(m) ' (P= 0.0003), and significant (P < 0.0001) decreases in T(g) '. A mixture design was used to predict the optimum levels of lactose and trehalose required to attain the minimum and maximum T(g) ' and viscosity in solution at fixed protein contents. These mixtures were used to form the continuous phase of β-casein stabilized nanoemulsions (10% w/w sunflower oil) prepared by microfluidization at 70 MPa. Nanoemulsions were analyzed for T(g) ' & T(m) ', as well as viscosity, mean particle size, and stability. Increasing levels of β-casein (2.5% to 10% w/w) resulted in a significant (P < 0.0001) increase in viscosity (5 to 156 mPa.s), significant increase in particle size (P= 0.0115) from 186 to 199 nm, and significant decrease (P= 0.0001) in T(g) ' (-45 to -50 °C). Increasing the protein content resulted in a significant (P < 0.0001) increase in nanoemulsion stability. A mixture DOE was successfully used to predict glass transition and rheological properties for development of a continuous phase for use in nanoemulsions.     

Amyloglucosidase-catalyzed synthesis of n-octyl-d-glucoside—analysis using response surface methodology

Amyloglucosidase (3.2.1.3)-catalyzed synthesis of n-octyl-d-glucoside was optimized using response surface methodology. A central composite rotatable design involving 32 experiments of five variables at five levels was employed to study the glucosylation reaction. Among the variables studied, namely, n-octanol (15–75 MEq to d-glucose), enzyme (20–100 mg ), pH (4.0–8.0), buffer volume (0.2–1.0 ml) and temperature (30–70°C), amyloglucosidase concentration, pH and temperature were found to be significant. Experimental data fitted the second-order polynomial equation well, as indicated by an R² value of 0.895. Validation experiments carried out under predicted conditions showed good correspondence between experimental and predicted yields. Various surface plots were generated to describe the relationship between operating variables and the conversion yields. The highest yield of 53.5% predicted at optimum conditions of 75 Eq n-octanol, 20 mg amyloglucosidase, 0.2 ml, pH 7.8 buffer at 50 °C showed good correspondence to the experimental yield of 53.8% under these conditions.     

Optimisation of conditions for the preparation of β-carotene nanoemulsions using response surface methodology

Response surface methodology (RSM) was used to optimise the conditions for preparing β-carotene nanoemulsions. The effects of β-carotene (0.2–1.8%, w/w) and emulsifier (6.9–13.1%, w/w) concentrations, the homogenization pressure (79.1–140.9 MPa) and temperature (34.5–65.5 °C) on the particle size and stability of the nanoemulsions were studied. Results showed that the experimental data could be adequately fitted into a second-order polynomial model with multiple regression coefficients (R²)$(R^2)$ of 0.921 and 0.981 for the particle size and stability, respectively. Homogenization pressure and β-carotene concentration and the quadrics of β-carotene concentration (P<0.05)$(P<0.05)$ had a significant effect on the particle size of the nanoemulsions. Homogenization temperature and pressure, β-carotene concentration, the quadrics of emulsifier concentration and the interactions between β-carotene and emulsifier concentrations and between homogenization temperature and emulsifier concentration (P<0.05)$(P<0.05)$ had a significant effect on the stability of the emulsions. The optimum conditions for preparing β-carotene nanoemulsions were predicted to be: homogenization pressure, 129 MPa; homogenization temperature, 47 °C; β-carotene concentration, 0.82%; emulsifier concentration, 8.2%.     

Preliminary study of the stiffness enhancement of wood–plastic composites using carbon nanofibers

Vapor-grown carbon nanofibers (CNFs) were compounded into polypropylene (PP) with southern pine wood flour (WF) by high shear melt blending to investigate the reinforcement effects of CNFs on the stiffness of conventional wood flour/plastic composites. CNF loadings of 1, 2 and 5 parts by weight per 100 parts of PP were employed with three WF levels (20, 40 and 60 parts). Maleated polypropylene (MAPP) was used as a coupling agent to improve WF to PP compatibility. The incorporation of CNFs significantly increased the modulus of elasticity of these nanocomposites with MAPP addition. The presence of 0.61 wt?% of CNF within a 36.6%WF/1.83%MAPP/61%PP composite exhibited a modulus (7590 MPa) that was 59% greater than its counterpart without CNF (36.8%WF/1.84%MAPP/61.4%PP) (4783 MPa) and 90% greater than pure PP. The origin of this enhancement is not yet understood.     

Modelling of thermal conductivity of knitted fabrics made of cotton–bamboo yarns using artificial neural network

Regenerated cellulosic fibre made from bamboo is gaining popularity for apparel use due to its improved functional properties. This paper presents the modelling of thermal conductivity of knitted fabrics made from blended yarns of cotton and bamboo fibres using an artificial neural network (ANN). Five parameters, namely knitted fabric structure type, yarn linear density, bamboo fibre proportion (%), fabric thickness and fabric areal density, were used as inputs to the ANN model. The developed model was able to predict the thermal conductivity of fabrics with very good accuracy. The trend analysis of the developed model revealed the influence of various input parameters on the thermal conductivity of knitted fabrics. These findings can be judiciously used for the selection of optimum material and structural parameters of knitted cellulosic fabrics for a particular end‐use.     

Study of the mineral profile of Catalonian “brut” cava using atomic spectrometric methods

The aim of this study was to investigate the content of several metals in different commercial sparkling wines, all of them with the denomination of origin cava, in order to characterise them. Sixteen metals were determined in 18 samples of cava by inductively coupled plasma atomic-emission spectrometry (ICP-AES), hydride generation atomic-absorption spectrometry (HG-AAS) and graphite furnace atomic-absorption spectrometry (GF-AAS). Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn were analysed by ICP-AES; HG-AAS was employed for As quantification and GF-AAS for Ni, Cd and Pb analysis. The procedure involved the degasification of the cava sample by sonication, followed by H₂O₂/H₂SO₄ treatment and heating in an oven.     

Prediction of panellists’ perception of bread crumb appearance using fractal and visual textural features

Ratings of visual characteristics of bread crumb images obtained by panellists were correlated with features obtained by digital fractal and texture analysis and simple thresholding. Trained panellists were asked to rate 168 bread crumb images on fineness, homogeneity and degree of orientation, using continuous line scales. The relative orientation of the main and secondary peaks of the image power spectrum was the only parameter related to the human perception of the degree of crumb orientation. Single fractal dimension terms correlated better with the panellists’ perception of grain fineness and homogeneity than the single crumb features from thresholding. Second-order polynomial models were significantly better (P < 0.01) in most predictors than simple linear models. Grain fineness was better approached by the method of relative differential box-counting fractal dimension (R ² = 0.822) whereas grain homogeneity was highly related to the mass fractal dimension (R ² = 0.820). Multiple linear models to estimate grain fineness with higher predictive capacity included predictors such as fractal dimension, mean intercellular distance and void fraction (R ² > 0.860).     

Improved incorporation and stabilisation of β-carotene in hydrocolloids using glycerol

In this paper, a novel method for the incorporation of the antioxidant β-carotene in hydrocolloid matrices is presented, which consists on the use of glycerol as the vehicle for incorporation. This alcohol has been observed to greatly photostabilise the carotenoid molecule within the hydrocolloid matrices without greatly affecting the mechanical properties of the materials. The UV stability of β-carotene in the different hydrocolloid films developed (including starch, soy protein, whey protein concentrate, gelatin and zein) has been studied using UV/visible spectrophotometry, colorimetry and Raman spectroscopy. Raman images of the materials were also generated in order to ascertain the dispersion of the antioxidant within the hydrocolloid materials and it was observed that β-carotene was partially agglomerated in certain areas of the film, fact that could also contribute to enhance the stability of the bioactive molecule.     

Modulation of physicochemical properties of lipid droplets using β-lactoglobulin and/or lactoferrin interfacial coatings

There is considerable interest in the development of food-grade delivery systems to encapsulate, protect and release bioactive lipids. In this study, emulsion-based delivery systems were prepared consisting of lipid droplets covered by β-lactoglobulin (BLG) and/or lactoferrin (LF) coatings. BLG and LF are globular proteins with relatively low (pI ∼ 5) and high (pI ∼ 8) isoelectric points, respectively. Mixed systems were prepared by adding LF to BLG-stabilized corn oil-in-water emulsions (BLG/LF-coated droplets) or by adding BLG to LF-stabilized corn oil-in-water emulsions (LF/BLG-coated droplets) at pH 7, where there is an electrostatic attraction between the proteins. The influence of pH (3–7), ionic strength (0–60 mM CaCl₂ or 0–200 mM NaCl, pH 7), and thermal treatment (21–90 °C, pH 7, 20 min) on the physical stability of the resulting emulsions was examined. Emulsions with good stability to pH, salt, and thermal processing could be created using mixed interfacial coatings. In addition, we found that the lipids in these emulsions could still be digested using an in vitro digestion model to simulate small intestine conditions. This work may lead to the formation of emulsion-based delivery systems with improved physicochemical and functional performance.     

Improvement of the stability of nattokinase using γ-polyglutamic acid as a coating material for microencapsulation

In this study, nattokinase (NK) was microencapsulated in high-molecular-weight Na-γ-PGA, and the amount of NK added to the Na-γ-PGA was in the ratio of 1:1 and 2:1 w/w, which was designated as NK-100 and NK-200, respectively. The temperature and pH stability of microencapsulated NK were found to be higher than those of the free form. Free NK lost its overall initial activity after treatment at a temperature above 60 °C or at a pH less than 5.0 for 1 h. NK-100 and NK-200 retained 35% and 60% of their activities after exposure to an acidic condition of pH 4.0 and possessed 18% and 25% activity after treatment at 60 °C for 1 h, respectively. Furthermore, NK-100 and NK-200 exhibited more protective bioactivity than free NK did in storage stability tests. This simple and versatile approach can be potentially applied to the microencapsulation of various biomolecules for drug-delivery applications.     

Continuous separation of α-cyclodextrin and glucose using a simulated moving-bed adsorber

α-Cyclodextrin and glucose were continuously separated by a simulated moving-bed adsorber made up of four or 12 columns packed with the sodium ion form of a cation exchanger. In both cases, the components were successfully separated. The effect of the number of columns constituting the adsorber on the recovery of α-cyclodextrin was examined theoretically. The use of more than eight columns resulted in almost the same recovery.     

Recipe prediction of mélange yarn using modular artificial neural network

Mélange yarn is produced by mixing some pre-dyed fibers, as a part of mélange yarn manufacturing process, predicting the recipe, i.e. a list of percentages of pre-dyed fibers, is the most important and difficult step. Artificial neural network (ANN) is considered as a more effective recipe prediction method than the traditional model. In order to improve the application performances of neural network in recipe prediction of mélange yarn under the condition of larger data-set, this paper proposed a new framework to carry out recipe prediction of top dyed mélange yarn from reflectance spectra using the concept of modular artificial neural network (MANN), which decomposed the whole data-set into different units by taking a dyed fiber as a module unit. Compared with ANN, MANN showed a clear superiority in correlation coefficient, training execution time, as well as root-mean-square error of recipe. The average CMC (2:1) color difference of the predicted spectrum obtained with MANN model was 1.26, which was much lower than that obtained with ANN (~3.94), indicating that MANN model was more accurate than ANN. Even the color differences were not small enough in practice, it still could be used as a recognition method to find out the main compounds of mélange yarn, which would be very helpful for accurate color matching.     

Extension of Tosèla cheese shelf-life using non-starter lactic acid bacteria

Six strains of non-starter lactic acid bacteria (NSLAB) were used to extend the shelf-life of the fresh cheese Tosèla manufactured with pasteurised cows’ milk. The acidification kinetics of three Lactobacillus paracasei, one Lactobacillus rhamnosus and two Streptococcus macedonicus were studied in synthetic milk medium. Lb. paracasei NdP78 and NdP88 and S. macedonicus NdP1 and PB14-1 showed an interesting acidifying capacity and were further characterised for growth in UHT milk and production of antimicrobial compounds. Lb. paracasei NdP78 and S. macedonicus NdP1 grew more than 2 log cycles in 6 h. Lb. paracasei NdP78 was also found to produce a bacteriocin-like inhibitory substance (BLIS) active against Listeria monocytogenes. The four NSLAB strains (singly or in combination) were used to produce experimental pilot-scale cheeses which were compared by a panel. The cheese manufactured with the mixed culture Lb. paracasei NdP78 - S. macedonicus NdP1 was the most appreciated for its sensory properties. The cheeses produced at factory-scale showed higher concentrations of lactobacilli (7.90 log CFU/g) and streptococci (6.10 log CFU/g), but a lower development of coliforms (3.10 log CFU/g) and staphylococci (2.78 log CFU/g) than control cheese (4.86, 4.89, 4.93 and 5.00 log CFU/g of lactobacilli, streptococci, coliforms and staphylococci, respectively) processed without NSLAB addition. The food pathogens Salmonella spp. and Listeria monocytogenes were never detected. The dominance of the species inoculated was demonstrated by denaturing gradient gel electrophoresis (DGGE), whereas strain recognition was evaluated by randomly amplified polymorphic DNA (RAPD)-PCR. From the results obtained, Lb. paracasei NdP78 and S. macedonicus NdP1 were able to persist during the storage of Tosèla cheese and their combination influenced positively the sensory characteristics and shelf-life of the final product.     

Stabilizing vitamin D3 using the molten globule state of α-lactalbumin

α-Lactalbumin (α-LA) is the second most abundant bovine whey protein. It has been intensively studied because of its readiness to populate the molten globular (MG) state, a partially folded state with native levels of secondary structure but loss of tertiary structure. The MG state of α-LA exposes a significant number of hydrophobic patches that could be used to bind and stabilize small hydrophobic molecules such as vitamin D₃ (vitD). Accordingly, we tested the ability of α-LA to stabilize vitD in a pH interval from 7.4 to 2; over this pH interval, α-LA transitions from the folded state to the MG state. The MG state stabilized vitD better than the folded state and was superior to the major bovine whey protein β-lactoglobulin (β-LG), which is known to stabilize vitD. At pH 7.4, β-LG and α-LA stabilized vitD to the same extent. Tryptophan fluorescence quenching measurements indicated that α-LA has one binding site at pH 7.4 but acquires an additional binding site when the pH is lowered to pH 2 to 4. Stability measurements of the vitD in the α-LA–vitD complex at different temperatures suggest that UHT processing would lead to little loss of vitD. This study demonstrates the potential of α-LA as a component in vitD fortification, particularly for low pH applications.     

Determining the gelation temperature of β-lactoglobulin using in situ microscopic imaging

Evolution of microstructure during heat-induced gelation of β-lactoglobulin (β-LG) was investigated in situ using confocal laser scanning microscopy at various gel-preparation conditions: pH = 2, 5, and 7; protein content = 5, 10, and 15%; and salt (NaCl) content = 0, 0.1, and 0.3 M. The number and area of evolving β-LG clusters were observed as a function of time and temperature and the data were fitted to a log-normal model and sigmoid model, respectively. The gelation temperature (T_gel) of the β-LG system was determined from both the number (T_gel/N) and total area (T_gel/A) of β-LG clusters versus temperature data. The range of T_gel/N and T_gel/A values for all the cases was 68 to 87°C. The effect of pH was the most dominant on T_gel/N and T_gel/A, whereas the effects of β-LG and salt contents were also statistically significant. Therefore, the combined effect of protein concentration, pH, and salt content is critical to determine the overall gel microstructure and T_gel. The T_gel/N and T_gel/A generally agreed well with T_gel determined by dynamic rheometry (T_gel/R). The correlations between T_gel/N and T_gel/A versus T_gel/R were 0.85 and 0.72, respectively. In addition, T_gel/N and T_gel/A values compared well with T_gel/R values reported in the literature. Based on these results, T_gel/N determined via in situ microscopy appears to be a fairly good representative of the traditionally measured gelation temperature, T_gel/R.