Volatile release and structural stability of β-lactoglobulin primary and multilayer emulsions under simulated oral conditions

Review of Emission Characteristics and Purification Methods of Volatile Organic Compounds (VOCs) in Cooking Oil Fume

Volatile organic compounds (VOCs) in cooking oil fumes need to be efficiently removed due to the significant damage they cause to the environment and human health. This review discusses the emission characteristics, which are influenced by different cooking temperatures, cooking oils, and cuisines. Then, various cooking oil fume purification methods are mainly classified into physical capture, chemical decomposition, and combination methods. VOCs removal rate, system operability, secondary pollution, application area, and cost are compared. The catalytic combustion method was found to have the advantages of high VOC removal efficiency, environmental protection, and low cost. Therefore, the last part of this review focuses on the research progress of the catalytic combustion method and summarizes its mechanisms and catalysts. The Marse-van Krevelen (MVK), Langmuir-Hinshelwood (L-H), and Eley-Rideal (E-R) mechanisms are analyzed. Noble metal and non-noble metal catalysts are commonly used. The former showed excellent activity at low temperatures due to its strong adsorption and electron transfer abilities, but the high price limits its application. The transition metals primarily comprise the latter, including single metal and composite metal catalysts. Compared to single metal catalysts, the interaction between metals in composite metal catalysts can further enhance the catalytic performance.

Flavor release and stability comparison between nano and conventional emulsion as influenced by saliva

Flavour release and emulsion stability depend on volatile organic compounds' environmental conditions, food microstructure, and physicochemical properties. The effect of pH (3.5 vs 7.0) and saliva addition on stability and flavour release from nano and conventional emulsions was investigated using particle size, charge and Lumisizer measurments. Larger particle sizes were observed at lower pressures and in saliva-containing emulsions. At 1700 bar, nano-emulsions (below 150 nm) were created at pH 3.5 and 7.0 including saliva-containing emulsions. As was clear from the creaming velocity measurements, saliva addition decreased the emulsion stability by reducing particle charges and increased viscosity by more than 50%, especially when prepared at pH 3.5 closer to the isoelectric point of the used emulsifier β-lactoglobulin (pH 5.2). (5.2). Flavour release from emulsions was measured at equilibrium using a phase ratio variation to determine partition coefficients and dynamically using an electronic nose. Partition coefficients of the flavour compounds for most conditions were two to four times lower in emulsions prepared at pH 7.0 than at pH 3.5 and in emulsions without saliva. Emulsions prepared with higher pressures showed stronger flavor release rates, while additional salvia dropped the release rate for ethyl acetate at pH 3.5. The physicochemical properties of flavour compounds, saliva addition and pH of emulsions influenced flavour release more than homogenization pressures. The potential in using nano-emulsions in food applications an be attributed higher stability and enhanced flavor release.

The role of capsaicin stimulation on the physicochemical properties of saliva and aroma release in model aqueous and oil systems

Capsaicin increases saliva production, but the impact of this additional saliva on the food matrix is unknown. This study aimed to explain the impact of capsaicin on saliva properties and in-vivo release of 14 aroma compounds in aqueous [aqu] and oil systems [oil]. To investigate the physicochemical effect from diverse properties of aroma compounds, one healthy subject participated in all the sessions to minimise large variations between individuals. Capsaicin enhanced saliva flow rate (by 172% [aqu] and 85% [oil]) and salivary protein concentration (by 142% [aqu] and 149% [oil]). Furthermore, capsaicin-in-oil stimulated saliva formed a more stable emulsion in the mouth (17% higher zeta-potential and 15% smaller particle size). In-nose release concentrations measured by APCI-MS for certain esters were reduced by capsaicin (e.g., isoamyl acetate was reduced by 65% [aqu] and 76% [oil]), which suggests that capsaicin may induce stronger oral interactions between specific aroma compounds and salivary proteins.

Progress in Colloid Delivery Systems for Protection and Delivery of Phenolic Bioactive Compounds: Two Study Cases—Hydroxytyrosol and Curcumin

Insufficient intake of beneficial food components into the human body is a major issue for many people. Among the strategies proposed to overcome this complication, colloid systems have been proven to offer successful solutions in many cases. The scientific community agrees that the production of colloid delivery systems is a good way to adequately protect and deliver nutritional components. In this review, we present the recent advances on bioactive phenolic compounds delivery mediated by colloid systems. As we are aware that this field is constantly evolving, we have focused our attention on the progress made in recent years in this specific field. To achieve this goal, structural and dynamic aspects of different colloid delivery systems, and the various interactions with two bioactive constituents, are presented and discussed. The choice of the appropriate delivery system for a given molecule depends on whether the drug is incorporated in an aqueous or hydrophobic environment. With this in mind, the aim of this evaluation was focused on two case studies, one representative of hydrophobic phenolic compounds and the other of hydrophilic ones. In particular, hydroxytyrosol was selected as a bioactive phenol with a hydrophilic character, while curcumin was selected as typical representative hydrophobic molecules.

Developing Activated Carbon Veil Electrode for Sensing Salivary Uric Acid

The paper describes the development of a carbon veil-based electrode (CVE) for determining uric acid (UA) in saliva. The electrode was manufactured by lamination technology, electrochemically activated and used as a highly sensitive voltammetric sensor (CVEact). Potentiostatic polarization of the electrode at 2.0 V in H2SO4 solution resulted in a higher number of oxygen and nitrogen-containing groups on the electrode surface; lower charge transfer resistance; a 1.5 times increase in the effective surface area and a decrease in the UA oxidation potential by over 0.4 V, compared with the non-activated CVE, which was confirmed by energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, chronoamperometry and linear sweep voltammetry. The developed sensor is characterized by a low detection limit of 0.05 µM and a wide linear range (0.09-700 µM). The results suggest that the sensor has perspective applications for quick determination of UA in artificial and human saliva. RSD does not exceed 3.9%, and recovery is 96-105%. UA makes a significant contribution to the antioxidant activity (AOA) of saliva (≈60%). In addition to its high analytical characteristics, the important advantages of the proposed CVEact are the simple, scalable, and cost-effective manufacturing technology and the absence of additional complex and time-consuming modification operations.

Impact of proteins and polysaccharides on flavor release from oil-in-water emulsions during simulated cooking

Our objective was to establish the influence of biopolymer additives on the flavor release profiles of model food emulsions during simulated cooking. Allyl methyl disulfide (AMDS), a volatile hydrophobic flavor found in garlic, was used as a model aroma. This type of flavor compound is easily lost from foods during thermal processing and so there is a need to identify effective strategies to improve its retention and modulate its release profile. The impact of protein (sodium caseinate and whey protein) and polysaccharide (maltodextrin, xanthan gum, sodium alginate, corn starch, methyl cellulose, and β-cyclodextrin) addition (0.5%) on the flavor retention profile of AMDS-loaded emulsions subjected to simulated cooking was determined. Corn oil was used as the oil phase to formulate the oil-in-water emulsions. Emulsions were heated from room temperature to boiling and then held for 30 min to establish the impact of biopolymer addition on their flavor retention profiles. The impact of biopolymer concentration on flavor retention was also studied using maltodextrin (0-40%) and xanthan gum (0-0.5%). The flavor retention profiles of the emulsions containing 0.5% maltodextrin, sodium alginate, whey protein, sodium caseinate, or corn starch, were the same as those as the control (no additives). Conversely, addition of 0.5% methyl cellulose, β-cyclodextrin, or xanthan gum led to faster flavor release during cooking. The thermal stability of the emulsions appeared to be the dominant factor determining their flavor release: additives that promoted coalescence during heating led to faster flavor release. Moreover, addition of high levels of maltodextrin and xanthan gum promoted depletion flocculation, which also led to faster flavor release during heating. In contrast, there appeared to be no correlation between emulsion viscosity and the flavor release profile. These results are important for designing emulsion-based food products, such as sauces and soups, with controlled flavor release profiles during cooking.

Rheological investigation of high-acyl gellan gum hydrogel and its mixtures with simulated body fluids

Purpose

Most of the studies concerning gellan have been focused on its application as a food ingredient, however, gellan is often considered as a candidate for the development of novel pharmaceutical formulations. Taking into account that gellan is ion-sensitive, it can be assumed that its initial mechanical properties can change upon contact with body secretions. Therefore, the aim of the work was to investigate the rheological properties of pure high-acyl gellan gum hydrogel (0.4%) and its mixtures with selected simulated body fluids.

Methods

The rheological investigations were performed on rotational rheometer and included oscillatory temperature, amplitude, and frequency sweeping. The results enabled estimation of the linear viscoelastic regime, calculation of the cross-over points, and percentage of structure recovery.

Results

In the case of pure hydrogel no evidence of thermosensitivity was observed in the range of 20–40°C. In pH = 1.2 (NaCl/HCl) the hydrogel structure was almost entirely destroyed. Mixing with phosphate buffer (pH = 4.5) resulted in higher gel strength than after dilution with deionized water. The opposite effect was observed in the case of pH = 7.4. The studies performed for the mixture of GG hydrogel and mucin indicated interaction between the components. The hydrogel elasticity increased in the presence of simulated tear, but decreased in simulated saliva and vaginal fluid.

Conclusions

In this study, it was shown that the stability of a three-dimensional gellan structure may be affected by pH and the presence of mucin which most probably competed with gellan gum in divalent cations binding. The observations presented in this study may be important in terms of potential application of gellan gum as a potential carrier in drug delivery systems.

Tunable volatile release from organogel-emulsions based on the self-assembly of β-sitosterol and γ-oryzanol

A current challenge in the area of food emulsion is the design of microstructure that provides controlled release of volatile compounds during storage and consumption. Here, a new strategy addressed this problem at the fundamental level by describing the design of organogel-based emulsion from the self-assembly of β-sitosterol and γ-oryzanol that are capable of tuning volatile release. The results showed that the release rate (v₀), maximum headspace concentrations (C_max) and partition coefficients (k_a/e) above structured emulsions were significantly lower than unstructured emulsions and controlled release doing undergo tunable though the self-assembled interface and core fine microstructure from internal phase under dynamic and static condition. This result provides an understanding of how emulsions can behave as delivery system to better design novel food products with enhanced sensorial and nutritional attributes.

Mammalian gastrointestinal tract parameters modulating the integrity, surface properties, and absorption of food-relevant nanomaterials

Many natural chemicals in food are in the nanometer size range, and the selective uptake of nutrients with nanoscale dimensions by the gastrointestinal (GI) tract is a normal physiological process. Novel engineered nanomaterials (NMs) can bring various benefits to food, e.g., enhancing nutrition. Assessing potential risks requires an understanding of the stability of these entities in the GI lumen, and an understanding of whether or not they can be absorbed and thus become systemically available. Data are emerging on the mammalian in vivo absorption of engineered NMs composed of chemicals with a range of properties, including metal, mineral, biochemical macromolecules, and lipid-based entities. In vitro and in silico fluid incubation data has also provided some evidence of changes in particle stability, aggregation, and surface properties following interaction with luminal factors present in the GI tract. The variables include physical forces, osmotic concentration, pH, digestive enzymes, other food, and endogenous biochemicals, and commensal microbes. Further research is required to fill remaining data gaps on the effects of these parameters on NM integrity, physicochemical properties, and GI absorption. Knowledge of the most influential luminal parameters will be essential when developing models of the GI tract to quantify the percent absorption of food-relevant engineered NMs for risk assessment.

Influence of olive oil phenolic compounds on headspace aroma release by interaction with whey proteins

The release of volatile compounds in an oil-in-water model system obtained from olive oil-whey protein (WP) pairing was investigated by considering the effect of phenolic compounds. Human saliva was used to simulate mouth conditions by retronasal aroma simulator (RAS) analysis. Twelve aroma compounds were quantified in the dynamic headspace by SPME-GC/MS. The results showed significant influences of saliva on the aroma release of virgin olive oil (VOO) volatiles also in the presence of WP. The interaction between WP and saliva leads to lower headspace release of ethyl esters and hexanal. Salivary components caused lower decrease of the release of acetates and alcohols. A lower release of volatile compounds was found in the RAS essay in comparison to that in orthonasal simulation of only refined olive oil (without addition of saliva or WP), with the exception of hexanal and 1-penten-3-one, where a significantly higher release was found. Our results suggest that the extent of retronasal odor (green, pungent) of these two volatile compounds is higher than orthonasal odor. An extra VOO was used to verify the release in model systems, indicating that WP affected aroma release more than model systems, while saliva seems to exert an opposite trend. A significant increase in aroma release was found when phenolic compounds were added to the system, probably due to the contrasting effects of binding of volatile compounds caused by WP, for the polyphenol-protein interaction phenomenon. Our study could be applied to the formulation of new functional foods to enhance flavor release and modulate the presence and concentrations of phenolics and whey proteins in food emulsions/dispersions.

Volatile release from whey protein isolate-pectin multilayer stabilized emulsions: effect of pH, salt, and artificial salivas

Whey protein isolate (WPI) and pectin can form a multilayer at the oil-water interface when they are oppositely charged. In this study, effects of pH, salt, and artificial salivas on emulsion stability and volatile release from multilayer emulsions were investigated. Results showed that emulsions (0.5 wt % WPI, 10 wt % oil) with pectin content ≤0.1 wt % had rapid phase separation at pH 4 and 5, and emulsions with higher pectin content (≥0.2 wt %) had good stability. Due to an electrostatic screening effect, multilayer emulsions collapsed when subjected to ≥150 mM NaCl solutions at pH 5. When diluted with artificial salivas containing salts, mucin, and/or α-amylase, multilayer emulsions showed rapid droplet aggregation. GC headspace analysis found that volatiles had significantly lower initial headspace concentration (C(initial)) in multilayer emulsions, and the C(initial) correlated negatively with pectin content in emulsions. Emulsions at pH 7 had more volatiles released to the headspace than emulsions at pH 5. However, changes in pectin content and pH did not show a significant effect on release rate of most volatile compounds. In salt-treated multilayer emulsions, C(initial) and release rates of volatiles increased with NaCl content. Addition of salivas triggered higher release of hydrophobic volatiles and lower release of hydrophilic volatiles, which was mostly due to dilution effect and saliva-induced emulsion instability.