The effect of the molecular structure of hydroxypropyl methylcellulose on the states of water, wettability, and swelling properties of cryogels prepared with and without CaO2.

Hydroxypropyl methylcellulose (HPMC) belongs to the cellulose ether family that has hydroxyl groups substituted by hydrophobic methyl groups (DS) and hydrophilic hydroxypropyl groups (MS). Herein, the interactions between water molecules and cryogels prepared with HPMC in the presence and absence of a linear nonionic surfactant, as well as CaO2 microparticles, which react with water producing O2, were systematically investigated by sorption experiments and Time-Domain Nuclear Magnetic Resonance. Regardless of the DS and MS, most water molecules presented transverse relaxation time t2 typical of intermediate water and a small population of more tightly bound water. HPMC cryogels with the highest DS of 1.9 presented the slowest swelling rate of 0.519 ± 0.053 gwater/(g.s) and the highest contact angle values 85.250o ± 0.004o, providing the best conditions for a slow reaction between CaO2 and water. The presence of surfactant favored hydrophobic interactions that allowed the polar head of the surfactant to be exposed to the medium, resulting in a higher swelling rate and lower contact angle values. The HPMC with the highest MS presented the fastest swelling rate and the lowest contact angle. These findings are relevant for the formulations and reactions, where tuning the swelling kinetics is crucial for the final application.

Understanding the Performance of Plant Protein Concentrates as Partial Meat Substitutes in Hybrid Meat Emulsions.

Hybrid meat products are an excellent strategy to incorporate plant proteins into traditional meat formulations considering recent market trends focusing on the partial reduction in red meat content. In this work, we evaluated the effects of different concentrated plant proteins (soy, pea, fava bean, rice, and sunflower) in partially replacing meat in meat emulsion model systems. Soy, pea, and sunflower proteins showed great compatibility with the meat matrix, giving excellent emulsion stability and a cohesive protein network with good fat distribution. Otherwise, adding rice and fava bean proteins resulted in poor emulsion stability. Color parameters were affected by the intrinsic color of plant proteins and due to the reduction in myoglobin content. Both viscoelastic moduli, G' and G″ decreased with the incorporation of plant proteins, especially for rice and fava bean. The temperature sweep showed that myosin denaturation was the dominant effect on the G' increase. The water mobility was affected by plant proteins and the proportion between immobilized and intermyofibrillar water was quite different among treatments, especially those with fava bean and rice proteins. In vitro protein digestibility was lower for hybrid meat emulsion elaborated with rice protein. It is concluded that soy, pea, and mainly sunflower proteins have suitable compatibility with the meat matrix in emulsified products.

Inulin gelled emulsion as a fat replacer and fiber carrier in healthier Bologna sausage.

The effects of gelled emulsions (GE) used as animal fat replacers in terms of the nutritional, technological, and sensory properties of Bologna sausages during 60 days of chilled storage have been studied. Samples with GE added exhibited a fat reduction of 31%. Sausages with GE had higher values of L* and lower values of a* compared to the control. Harder sausages were obtained by the addition of GE. Higher lipid oxidation rates were found with increasing amounts of GE in the reformulated products. In addition, the relaxation time was not affected by the reformulation. All samples were deemed acceptable by consumer tests. However, CATA (Check-all-that-apply) tests showed that Bolognas formulated with partial or total pork fat replaced with GE were described as rubbery, not very spicy and firm, appeared to be dry and opaque, and had an aftertaste. Chilled storage significantly affected the Thiobarbituric Acid Reactive Substances (TBARS) values and slightly affected the pH values, texture, color, and NMR data. An important result is that the panelists did not detect the oxidation results in relation to the TBARS values, and the addition of a GE with inulin as dietary fiber may be a good strategy to make Bologna sausage healthier.

Organogels in low-fat and high-fat margarine: A study of physical properties and shelf life.

This study aimed to investigate the effect of the addition of organogels in low-fat and high-fat margarines during storage. Margarine formulations were made using water: oil ratios of 65:35 and 40:60 (w/w), and a lipid phase composed of organogel made with soybean oil, candelilla wax, fully hydrogenated palm oil, and mononoacylglycerols. The thermal stability, particle size, consistency, peroxide index, oil exudation, and microstructure of the margarines were evaluated for six months of storage. All margarines showed thermal stability at 35 °C, with no physical destabilization during the period studied. Both low-fat and high-fat margarines presented similar particle size distribution, with d3.3 around units of 5 µm. The peroxide index of the margarines ranged from 1.27 to 5.97 meq O2/Kg after six months of storage. High-fat margarines showed greater hardness and lower spreadability. The amount of water added to the formulations affected the stability, particle size, and texture of the margarines. It was possible to produce margarines with different fat contents and greater health appeal. The margarines with 60% and 35% fat exhibited 12.00 and 8.03% SFA; 32.63 and 18.20% PUFA; and 14.37 and 8.20% MUFA, respectively.

Inclusion Complexation between α-Cyclodextrin and Oligo(ethylene glycol) Methyl Ether Methacrylate.

The preparation of inclusion complexes based on α-cyclodextrin (α-CD) and oligo(ethylene glycol) methyl ether methacrylate (OEGMA) was investigated aiming to reveal complexation particularities and thermodynamic and kinetic aspects as a function of the oligomer architecture. Small-angle X-ray scattering and isothermal titration calorimetry measurements revealed that oligomer molecular weight controls both the kinetics and thermodynamics of inclusion. Unlike linear ethylene glycol polymers, OEGMA groups possess a methacrylate group, which seems to act as a stopper, affecting their mode of complexation. Nuclear magnetic resonance spectra and relaxation measurements support the fact that methacrylate groups lie outside the α-CD ring and that a full sequential complexation of the oligomer ethylene oxide groups is not observed. These results allied to the temperature sensitivity of these oligomers and enable possible routes for chemical modifications and design of new stimuli-responsive materials.

Reducing phosphate in emulsified meat products by adding chia (Salvia hispanica L.) mucilage in powder or gel format: A clean label technological strategy.

This study evaluated the functional properties of chia mucilage powder (MCP) and gel (MCG) as a phosphate replacers in low-fat Bologna sausages. Four treatments were produced without phosphates (F1-2% MCP; F2-2% MCG; F3-4% MCP; F4-4% MCG) and two with 0.25% phosphate (F5-2% MCG and F6-4% MCG) besides control (20%-fat-0.5% phosphate). Samples containing mucilage were less firm and less chewy on day 0, except F3. Treatments containing 2% MCG were judged acceptable and provided better emulsion stability than those with MCP. Adding 4% MCP or MCG resulted in Bolognas with lower relaxation times and more restricted mobility and lowest sensorial acceptance characterized by the terms light brown and dark pink color (F4). The microscopy images exhibited less cohesive structure in treatments with 4% of MCG, suggesting the formation of a weaker bound protein network. Chia mucilage gel at 2%, due to its functional properties, has proven to be a feasible strategy to substitute 50% phosphate in low-fat Bologna sausages.

Understanding the effect of different chloride salts on the water behavior in the salted meat matrix along 180 days of shelf life.

The objective of this study was to evaluate the effects of different chloride salts (NaCl, KCl, and CaCl2) on water behavior in salted meat during 180 days of shelf life by Low Field Nuclear Magnetic Resonance and physicochemical analysis. Four salted meat treatments were made using the following salts in the wet and dry salting steps: FC1: 100% NaCl; F1: 50% NaCl +50% KCl; F2: 50% NaCl +50% CaCl2; F3: 50% NaCl +25% KCl + 25% CaCl2. The analyses performed were: moisture, pH, aw, weight loss and Low Field Nuclear Magnetic Resonance. The use of CaCl2 as a salt substitute to NaCl during the elaboration of salted meat caused a decrease of pH and higher values of aw and weight loss when compared with the treatments containing only NaCl or NaCl + KCl. The morphology of the salted meat changed with the addition of CaCl2, possibly making the matrix structure more open and facilitating dehydration, whereas the NaCl replacement by KCl did not cause significant modifications in salted meat characteristics during 180 days of storage. In general, the results demonstrated that the addition of KCl may be a good alternative to reduce the sodium content in salted meat product, and the Low Field Nuclear Magnetic Resonance method has proved a good tool for obtaining additional information on the changes that salts can cause in the structure of salted meat products.

Controlled coagulation and redispersion of thermoresponsive poly di(ethylene oxide) methyl ether methacrylate grafted cellulose nanocrystals.

HYPOTHESIS: Cellulose nanocrystals (CNCs) undergo precipitation in the presence of high concentrations of cationic surfactants in aqueous solutions. To avoid such behavior and/or to promote redispersion of CNC/surfactant mixtures, the CNC surface was grafted with poly di(ethylene oxide) methyl ether methacrylate, P(MEO2MA). EXPERIMENTS: CNC-g-P(MEO2MA) was characterized using the following techniques 13C solid-state nuclear magnetic resonance (13C SSNMR), Fourier-transform infrared spectroscopy - attenuated total reflection spectroscopy (FTIR-ATR) and thermal gravimetric analysis (TGA). Isothermal titration calorimetry (ITC), electrophoretic mobility, light scattering and high sensitivity differential scanning calorimetry (HSDSC) were used to study the interaction between CNC-g-P(MEO2MA) and ionic surfactants, dodecyltrimethylammonium bromide (C12TAB, cationic) and sodium dodecylsulfate (SDS, anionic) at temperatures below and above the LCST. FINDINGS: CNC-g-P(MEO2MA) underwent phase separation above its lower critical solution temperature (LCST ∼ 25 °C) and precipitated from solution as seen by HSDSC and transmittance experiments. When C12TAB was added to CNC-g-P(MEO2MA) it induced the precipitation that prevented the redispersion due to strong electrostatic interactions with the negative charges on the CNC surface. With increasing concentrations of SDS, the polymer phase transition temperature was increased, which can be used to redisperse the CNC complexes. By removing SDS from the mixture via dialysis, the CNC-g-P(MEO2MA) underwent subsequent phase transition.

Quantitative (13)C MultiCP solid-state NMR as a tool for evaluation of cellulose crystallinity index measured directly inside sugarcane biomass.

BACKGROUND: The crystallinity index (CI) is often associated with changes in cellulose structure after biological and physicochemical pretreatments. While some results obtained with lignocellulosic biomass demonstrate a progressive increase in the CI as a function of pretreatments, it is also shown that the CI can significantly vary depending on the choice of the measurement method. Besides, the influence of the CI on the recalcitrance of biomass has been controversial for a long time, but the most recent results tend to point out that the efficiency of pretreatments in reducing the recalcitrance is not clearly correlated with the decrease of the CI. Much of this controversy is somewhat associated with the inability to distinguish between the CI of the cellulose inside the biomass and the CI of the full biomass, which contains other amorphous components such as lignin and hemicellulose. RESULTS: Cross polarization by multiple contact periods (Multi-CP) method was used to obtain quantitative (13)C solid-state nuclear magnetic resonance (ssNMR) spectra of sugarcane bagasse biomass submitted to two-step pretreatments and/or enzymatic hydrolysis. By comparing the dipolar filtered Multi-CP (13)C NMR spectra of untreated bagasse samples with those of samples submitted to acid pretreatment, we show that a 1% H2SO4-assisted pretreatment was very effective in removing practically all the hemicellulose signals. This led us to propose a spectral editing procedure based on the subtraction of MultiCP spectra of acid-treated biomass from that of the extracted lignin, to obtain a virtually pure cellulose spectrum. Based on this idea, we were able to evaluate the CI of the native cellulose inside the sugarcane bagasse biomass. CONCLUSIONS: The results show the validity of the proposed method as a tool for evaluating the variations in the CI of the cellulose inside biomasses of similar kinds. Despite a clear increase in the CI of biomass as measured by X-ray diffraction, no significant variations were observed in the CI of the cellulose inside the biomass after a particular 1% H2SO4/0.25-4% NaOH chemical-assisted pretreatments. The CI of cellulose inside the biomass solid fraction that remained after the enzymatic hydrolysis was also evaluated. The results show a slight increase in crystallinity.

Correlation between molecular conformation, packing, and dynamics in oligofluorenes: a theoretical/experimental study.

Fluorene-based systems have shown great potential as components in organic electronics and optoelectronics (organic photovoltaics, OPVs, organic light emitting diodes, OLEDs, and organic transistors, OTFTs). These systems have drawn attention primarily because they exhibit strong blue emission associated with relatively good thermal stability. It is well-known that the electronic properties of polymers are directly related to the molecular conformations and chain packing of polymers. Here, we used three oligofluorenes (trimer, pentamer, and heptamer) as model systems to theoretically investigate the conformational properties of fluorene molecules, starting with the identification of preferred conformations. The hybrid exchange-correlation functional, OPBE, and ZINDO/S-CI showed that each oligomer exhibits a tendency to adopt a specific chain arrangement, which could be distinguished by comparing their UV/vis electronic absorption and (13)C NMR spectra. This feature was used to identify the preferred conformation of the oligomer chains in chloroform-cast films by comparing experimental and theoretical UV/vis and (13)C NMR spectra. Moreover, the oligomer chain packing and dynamics in the films were studied by DSC and several solid-state NMR techniques, which indicated that the phase behavior of the films may be influenced by the tendency that each oligomeric chain has to adopt a given conformation.