Physicochemical characterization of corn–sorghum nixtamalized flours as a function of the steeping time

This work focused on the study of the physicochemical properties of nixtamalized corn and sorghum flours, as well as combined nixtamalized corn–sorghum flours with 10, 20, and 30 % of sorghum. The removal of the sorghum pericarp during nixtamalization depends on the steeping time and strongly influences the water and calcium uptake. The absence of the waxy layer in sorghum grain allows a faster water uptake in relation to corn grain. Changes in the pericarp structure during the steeping time govern the Ca absorption in sorghum grain. The partial removal of the pericarp and the most external layers of the endosperm produce the decrease in phosphorous content for corn and sorghum. The Ca/P ratio of nixtamalized corn/sorghum flours is greater than 1 for steeping time up to 3 h. Therefore, this fact could help the increase of Ca in the daily diet. Amylopectin is the predominant macromolecule in both starches. The pasting profiles showed a decrease in peak viscosity when the sorghum fraction increases; this is due to increases in fiber.     

Compositional and textural properties of milkfat–soybean oil blends following enzymatic interesterification

Milkfat–soybean oil blends were enzymatically interesterified (EIE) by Aspergillus niger lipase immobilized on SiO₂–PVA hybrid composite in a solvent free system. An experimental mixture design was used to study the effects of binary blends of milkfat–soybean oil (MF:SBO) at different proportions (0:100; 25:75; 33:67; 50:50; 67:33; 75:25; 100:0) on the compositional and textural properties of the EIE products, considering, as response variables, the interesterification yield (IY), consistency and hardness. Lipase-catalysed interesterification reactions increased the relative proportion of TAGs’ C₄₆–C₅₂ and decreased the TAGs’ C₄₀–C₄₂ and C₅₄ concentrations. The highest IY was attained (10.8%) for EIE blend of MF:SBO 67:33 resulting in a more spreadable material at refrigerator temperature in comparison with butter, milkfat or non-interesterified (NIE) blend. In this case, consistency and hardness values were at least 32% lower than values measured for butter. Thus, using A. niger lipase immobilized on SiO₂–PVA improves the textural properties of milkfat and has potential for development of a product incorporating unsaturated and essential fatty acids from soybean oil.     

Structural and physicochemical characterization of porous starch prepared by enzymatic hydrolysis,solvent-exchange,and freeze–thaw cross-linking treatments

Porous starches have been researched for applications of its characteristics, although it has been noted that different methods are used to influence the properties manifested. In this study, native starch isolated from hyacinth bean (Lablab purpureus) was used to create porous starch using three different methods, viz, solvent-exchange (SE), enzyme hydrolysis (EH), and addition of mercaptosuccinic acid known as freeze–thaw (FT). The structural characteristics (Fourier-transform infrared spectroscopy, X-Ray Diffraction) of SE and EH were very similar to those of NS. The gelatinization properties of the porous starches were higher (97.15–112.86) than those of NS (93.00–103.69). The pasting properties of SE and EH were improved, while FT did not possess any pasting abilities, this was due to its high solubility (42.92 ± 1.70) and lipophilic nature (4.63 ± 0.42). The adsorption properties of SE (4.0616.35) and EH (4.31–15.45) were similar to those of NS (3.53–15.50). The swelling power of SE (9.16 ± 0.19) and EH (9.25 ± 0.13) was similar to that of NS (9.76 ± 0.43), while the amylose contents (15.48–19.43) were lower than those of NS (20.68 ± 4.39). Only the SE (11.42 ± 3.40) from the porous starches had resistant starch present, while EH had mostly rapidly digestible (13.23 ± 0.00) and slowly digestible starch (127.16 ± 0.00). These structural and physicochemical characteristics show that these porous starches may be suitable in delivery systems, improving solubility of drugs and adsorbing dyes.     

Preparation and characterization of pullulan–chitosan and pullulan–carboxymethyl chitosan blended films

The characteristics of pullulan–chitosan and pullulan–carboxymethyl chitosan (CMCH) blended films were investigated. The viscosity of the film-forming solutions, mechanical properties, barrier properties (water and oxygen), water solubility, and color are reported. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) measurements were used to study the interactions and compatibility between the polysaccharides. The addition of the chitosan or CMCH to pullulan effectively modified the mechanical and oxygen barrier property of the film. The improvements in the film properties have been related to strong interactions between chitosan/CMCH and pullulan polymers, which were observed with FTIR spectroscopy. The ratio of pullulan and chitosan to achieve films with optimum mechanical properties, oxygen and water barrier properties was identified to be 1:1. Increased concentrations of chitosan lead to the formation of inter-molecular hydrogen bonds rather than the intra-molecular hydrogen bonds which were suggested from XRD measurements.     

Fabrication and characterization of exfoliated chitosan–gelatin–montmorillonite nanocomposite nanofibers

Polymeric nanofibers as one of the most known nanotechnology products have huge potential applications in many fields due to their high aspect ratio and porosity, being capable of formation of three-dimensional structures and having great mechanical and biological properties. Chitosan is a natural abundant polymer which has attracted huge interests in biomedical and biological industries due to its biocompatible, biodegradable, and non-toxicity properties. However, electrospinning of chitosan is found to be a great challenge, blending it with other polymers such as gelatin was explored as means to improve the morphological deficiencies of chitosan nanofibers and facilitate its electrospinnability. On the other hand, montmorillonite (MMT) has been attracted great attention due to its remarkable improvement in properties of polymeric composites nanofibers. The main objective of this work was on effect of concretion of gelatin–chitosan blends and MMT on morphology of resulted nanocomposite nanofibers. The x-ray diffraction data demonstrated the exfoliation of MMT layers. The morphology of electrospun chiosan–gelatin–MMT composite nanofibers was characterized using scanning electron microscope (SEM). The miscibility of blend was determined using SEM and Fourier transform infrared spectrometer/attenuated total reflectance.     

Addition of gelatin enhanced gelation of corn–milk yogurt

Corn–milk yogurt set by a combination of sodium caseinate plus gelatin at concentrations of 0, 0.2, 0.4 and 0.6% (w/v) were studied. The quality of the gels was determined by measurement of acidity, syneresis, texture profile analysis, viscoelasticity, structure scanning electron microscope and microbiology. Texture profile analysis (TPA) showed that increasing levels of gelatin increased hardness, adhesiveness and springiness as well as the acidity of the products. Viscoelastic behaviour displayed similar trends to the TPA characteristics, the storage modulus was less frequency dependent than the loss modulus giving a loss tangent of 0.2 in the high gelatin systems, which might indicate a true gel system. The microstructure was dense and spongy-like with small air cells, in particular, those having a high concentration of gelatin (0.6%, w/v) gave a very firm structure which might impair palatability. The addition of a commercial gelatin at 0.4% (w/v) gave good acceptability for the product (little syneresis of the gels produced). While the gelatin used for this study had a bloom value of 246 g the authors acknowledge that a different commercial gelatin may well result in a different concentration being required.     

Structural characterization of β-carotene-incorporated nanovesicles produced with non-purified phospholipids

The technical feasibility of obtaining β-carotene-incorporated phospholipid nanovesicles using non-purified soybean lecithins was studied. For this purpose, three lecithin-types were evaluated. Nanovesicles were characterized by average hydrodynamic diameter, particle size distribution, polydispersity index, ζ-potential, transmission electron microscopy, membrane microviscosity, small angle X-ray scattering and capacity of lipid peroxidation inhibition. In general, the β-carotene incorporation did not promote a significant increase on average hydrodynamic diameter, but vesicles produced from lecithins containing triglycerides showed lower polydispersity. The lecithin-type used to produce nanovesicles did not influence the β-carotene loading capacity, but significantly influenced the microviscosity of liposomal membrane and lipid peroxidation inhibition capacity. Non-enzymatically modified lecithin (containing or not triglycerides) showed similar efficiency and peroxidation inhibition capacity considering β-carotene incorporation. Therefore, low-cost non-purified lecithin can be employed for production of liposomal systems as an encapsulating and/or delivery system to be used in food products.     

Effect of virtual eating environment on consumers’ evaluations of healthy and unhealthy snacks

Immersive technologies such as virtual reality and augmented reality have been recently explored in the field of food consumption studies from different perspectives. The present study utilized virtual reality technology in a within-subject experiment with three conditions to examine whether a varying virtual eating environment can alter consumers’ emotional responses (positive, negative, neutral) to the eating situation and whether the resulting emotional responses correlate with consumers’ wanting, liking, and hedonic evaluations of healthy and unhealthy snacks. In addition, the study analyzed whether a virtual eating environment that generates a positive emotional response can raise consumers’ rating of a healthy snack to the same level as an unhealthy snack consumed in a plain, unimmersed environment. The results showed a correlation between positive emotional responses and the pre-tasting evaluations of both snacks. In terms of hedonic evaluations, positive emotional responses correlated mainly with consumers’ evaluation of the unhealthy snack. When pre-tasting wanting and liking evaluations are compared between experimental conditions, the results indicate that a healthy snack is rated higher in a virtual reality environment that induces a more positive emotional response. The healthy snack was also rated at the same level as the unhealthy snack consumed in a plain environment. No differences between conditions were observed in consumers’ hedonic evaluations of the products. EEG and heart rate measurement results indicate that this might be because tasting a healthy snack generates more cognitive processing than an unhealthy snack. This might reduce the influence of the virtual eating environment on consumers’ evaluations. To conclude, virtual reality technologies might have the potential to support consumers’ eating experiences and healthy food choices by improving their evaluations of the products.     

Quality assessment of corn snacks enriched with soybean ferritin among young healthy people and patient with Crohn’s disease: the effect of extrusion conditions

Fortified extruded snacks are convenient products to supplement malnourished patients’ diet, e.g. suffering from Crohn’s disease. The snacks were extruded with different additions of iron-biofortified sprouts under varying process conditions (temperature and humidity). The sensory profiling showed the correlation between extrusion temperature and snack stickiness (R = 0.835), crispiness (R = 0.727), hardness (R=−0.485), as well as the intensity of corn (R = 0.888), powder (R=−0.795), metallic (R=−0.606) and bitter (R=−0.901) tastes. The sprouts addition affected metallic taste (R = 0.606) and aroma (R = 0.666) intensity. The product desirability was compared between healthy people (HP) and Crohn’s patients (CP). Overall desirability positively correlated with taste desirability in both groups. In the HP group, taste desirability was associated with metallic taste (R=−0.857) and Fe(III) content (R=−0.717). Also, aroma desirability (connected with pyrazines) was more significant to HP. Higher tolerance of CP to metallic and bitter flavours was observed. This confirms that the taste and aroma preferences of CP and HP are different.     

Preparation and characterization of urea–formaldehyde adhesives modified with glyoxalated tannin

European Journal of Wood and Wood Products - Urea–formaldehyde (UF) resins are the most important type of adhesive for the preparation of wood-based panels, due to its good performance and...