Rheological characterization of traditional and light mayonnaises

Unravelling the impact of fat content on the microbial dynamics and spatial distribution of foodborne bacteria in tri-phasic viscoelastic 3D models

The aim of the current study is to develop and characterise novel complex multi-phase in vitro 3D models, for advanced microbiological studies. More specifically, we enriched our previously developed bi-phasic polysaccharide (Xanthan Gum)/protein (Whey Protein) 3D model with a fat phase (Sunflower Oil) at various concentrations, i.e., 10%, 20%, 40% and 60% (v/v), for better mimicry of the structural and biochemical composition of real food products. Rheological, textural, and physicochemical analysis as well as advanced microscopy imaging (including spatial mapping of the fat droplet distribution) of the new tri-phasic 3D models revealed their similarity to industrial food products (especially cheese products). Furthermore, microbial growth experiments of foodborne bacteria, i.e., Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa and Lactococcus lactis on the surface of the 3D models revealed very interesting results, regarding the growth dynamics and distribution of cells at colony level. More specifically, the size of the colonies formed on the surface of the 3D models, increased substantially for increasing fat concentrations, especially in mid- and late-exponential growth phases. Furthermore, colonies formed in proximity to fat were substantially larger as compared to the ones that were located far from the fat phase of the models. In terms of growth location, the majority of colonies were located on the protein/polysaccharide phase of the 3D models. All those differences at microscopic level, that can directly affect the bacterial response to decontamination treatments, were not captured by the macroscopic kinetics (growth dynamics), which were unaffected from changes in fat concentration. Our findings demonstrate the importance of developing structurally and biochemically complex 3D in vitro models (for closer proximity to industrial products), as well as the necessity of conducting multi-level microbial analyses, to better understand and predict the bacterial behaviour in relation to their biochemical and structural environment. Such studies in advanced 3D environments can assist a better/more accurate design of industrial antimicrobial processes, ultimately, improving food safety.

Nanocellulose from Cocoa Shell in Pickering Emulsions of Cocoa Butter in Water: Effect of Isolation and Concentration on Its Stability and Rheological Properties

There is a growing interest in developing new strategies to completely or partially replace cocoa butter in food and cosmetic products due to its cost and health effects. One of these alternatives is to develop stable emulsions of cocoa butter in water. However, incorporating cocoa butter is challenging as it solidifies and forms crystals, destabilizing the emulsion through arrested coalescence. Prevention against this destabilization mechanism is significantly lower than against coalescence. In this research, the rheological properties of nanocellulose from cocoa shell, a by-product of the chocolate industry, were controlled through isolation treatments to produce nanocellulose with a higher degree of polymerization (DP) and a stronger three-dimensional network. This nanocellulose was used at concentrations of 0.7 and 1.0 wt %, to develop cocoa butter in-water Pickering emulsion using a high shear mixing technique. The emulsions remained stable for more than 15 days. Nanocellulose was characterized using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), hot water and organic extractives, atomic force microscopy (AFM), degree of polymerization (DP), and rheological analysis. Subsequently, the emulsions were characterized on days 1 and 15 after their preparation through photographs to assess their physical stability. Fluorescent and electronic microscopy, as well as rheological analysis, were used to understand the physical properties of emulsions.

The effect of organic acids and storage temperature on lite salad dressing rheology and Zygosaccharomyces parabailii growth

Zygosaccharomyces parabailii (Z. parabailii) causes spoilage in salad dressings due to its tolerance to osmotic pressure. The objective of this study was to determine the effect of organic acids and storage temperatures (4, 10, and 25 °C) on Z. parabailii growth and salad dressing mechanical properties. Acetic, lactic, and gluconic acids were used alone and in combination to acidify salad dressing. Z. parabailii-challenged formulations containing acetic acid alone tended to have lower counts of Z. parabailii when compared to Z. parabailii-challenged formulations containing other acid combinations. Overall, storage temperature had the most impact on Z. parabailii growth over a 45-day storage. Acidulant type and combination impacted salad dressing mechanical properties. During the 45-day storage period, all formulations showed increased viscosity, a Herschel–Bulkley viscosity profile, and elastic-dominant viscoelastic behavior. The degree of change in rheological behaviors over time was dependent on the type of acid used in the formulation.

Concentrated Pickering emulsions stabilised by hemp globulin-caseinate nanoparticles: tuning the rheological properties by adjusting the hemp globulin : caseinate ratio

Industrial hemp (Cannabis sativa L.) is an underutilised novel protein source. However, the utilisation of hemp seed protein is limited by its low solubility in water. Soluble nanoparticles were made by complexing hemp globulin (HG) with sodium caseinate (SC) via a pH-cycling method. Oil-in-water Pickering emulsions were made with these co-assembled protein nanoparticles. The emulsions were composed of 70% oil phase and 30% water phase (v/v), and contained 2% protein (w/v, pure SC or HG-SC nanoparticles with an HG : SC ratio of 1 : 2 or 1 : 1). All emulsions were stable during 21 days of storage, as there was no phase separation, coalescence or flocculation. At day 0, all emulsions were solid-like (G' > G'') regardless of the protein composition. The rheological properties of the emulsions during storage could be tuned by controlling the HG : SC ratio in the HG-SC nanoparticles, i.e. the emulsions became more solid-like over time when there was more HG in the nanoparticles. In contrast, emulsions stabilised by pure SC became more liquid-like during storage. The internal structure and interactions within the emulsions were evaluated by fitting frequency sweep test data according to a co-operative theory of flow. The result suggested that the solid-like emulsion resulted from stronger short-range interactions between flocs of oil droplets, which developed during storage when there was more HG in the HG-SC nanoparticles, and not from the formation of a three-dimensional network. These HG-SC nanoparticles can be used to control the rheological properties of an emulsion during its shelf life.

Evaluating high pressure-treated corn and waxy corn starches as novel fat replacers in model low-fat O/W emulsions: A physical and rheological study

High hydrostatic pressure-treated corn starch (HPCS) and waxy corn starch (HPWCS) at three concentrations (10%, 15%, and 20%) were applied as novel fat replacers in a model low O/W emulsion at three fat reduction levels (FR, 25%, 50%, and 75%) and some physical, textural and rheological characteristics and stability of the samples were examined and compared with the control. Applying higher concentrations of HPCS and HPWCS increased the zeta potential, hardness and consistency (mainly for HPWCS samples), reversely decreased the Z-average particle size and polydispersity index of the reduced-fat emulsions, but augmenting FR levels caused a reverse inclination. The rheological assay cleared that the emulsions prepared with HPWCS had greater elastic modulus (G') and more gap between G' and viscous modulus (G″) at all concentrations than the HPCS-contained samples. The critical stress (τ_c) of 25FR samples were significantly higher than the control, showing the well stability of reduced-fat samples. Also, the τ_c of the HPCS-contained emulsions reduced meaningfully when the FR level increased from 25% to 75%, but for the HPWCS samples, fat reduction didn't change the τ_c value significantly up to 50% fat reduction. Based on Tangδ_s(n-LVE), HPWCS contained samples showed more spreadability than the HPCS-contained emulsions.

Design and Application of Hydrocolloids from Butternut Squash (Cucurbita moschata) Epidermis as a Food Additive in Mayonnaise-type Sauces

Hydrocolloids play a fundamental role in the design of new food products in their structure and functionality due to the interaction with the components of complex food matrices; for this reason, natural sources that are friendly to the environment must be sought for their extraction. A microstructure product such as mayonnaise is an oil-in-water-type emulsion design with the components of the complex varying from egg yolk, additives, spices, sugar, and other optional ingredients to improve its stabilities and organoleptic characteristics. The main objective of the study was to design and characterize the physicochemical, bromatological, and sensory analyses and rheological properties of the mayonnaise-type sauce formulated with hydrocolloids obtained from the epidermis of butternut squash (Cucurbita moschata) and xanthan gum. The rheological study allowed us to obtain a behavior of a non-Newtonian flow of the shear-thinning type for all the samples, and flow curves could be well described by the Carreau model (R ² ≥ 0.993). The samples exhibit a more elastic than viscous behavior, with a higher storage modulus than the loss modulus (G' > G″) in the evaluated frequency range. When performing the physicochemical analysis, pH values (4.02-4.28), titratable acidity (0.40-0.48), peroxide index (12.5-20 meq), and a stable behavior were achieved in all the formulations except for MS2, which showed instability. Regarding the sensory evaluation, the MS3 sample reflected the closest values to the control sample, with a higher level of satisfaction. On the other hand, the bromatological analysis of MS3 presented a humidity value of 55.3 ± 0.27; carbohydrates, 7.66 ± 0.42; protein, 0.87 ± 0.02; fiber, 0.94 ± 0.05; and ash, 0.54 ± 0.05. The development of this product contributes to the transformation and agro-industrial use of the butternut squash (C. moschata); likewise, it allows us to obtain a mayonnaise-type sauce with organoleptic and nutritional characteristics for human consumption.

Fabrication of Concentrated Palm Olein-Based Diacylglycerol Oil-Soybean Oil Blend Oil-In-Water Emulsion: In-Depth Study of the Rheological Properties and Storage Stability

The present study focused on investigating the storage stability of oil-in-water (O/W) emulsions with high oil volume fractions prepared with palm olein-based diacylglycerol oil (POL-DAG)/soybean oil (SBO) blends at 25 °C. The incorporation of different ratios of oil blends significantly influenced (p < 0.05) the texture, color, droplet size distribution, and rheological parameters of the emulsions. Only emulsions incorporated with 10% to 20% POL-DAG in oil phase exhibited pseudoplastic behavior that fitted the Power Law model well. Furthermore, the O/W emulsions prepared with POL-DAG/SBO blends exhibited elastic properties, with G’ higher than G”. During storage, the emulsion was found to be less solid-like with the increase in tan δ values. All emulsions produced with POL-DAG/SBO blends also showed thixotropic behavior. Optical microscopy revealed that the POL-DAG incorporation above 40% caused aggregated droplets to coalesce and flocculate and, thus, larger droplet sizes were observed. The current results demonstrated that the 20% POL-DAG substituted emulsion was more stable than the control emulsion. The valuable insights gained from this study would be able to generate a lot more possible applications using POL-DAG, which could further sustain the competitiveness of the palm oil industry.

Characteristics of low-fat mayonnaise using different modified arrowroot starches as fat replacer

Modified arrowroot starch was investigated as a fat replacer in mayonnaise. Arrowroot starch was modified by octenyl succinic anhydride (OSA), annealing (ANN), citric acid hydrolysis (CA), acetylation (ACT) and heat-moisture treatment (HMT). The different starch pastes were used to replace mayonnaise fat at levels of 30% and 50%. Color, viscoelastic properties, and emulsion stability of the fat-reduced mayonnaises and full-fat (FF) version were evaluated, according to the type of modified starch and fat replacement ratio. Physicochemical, thermal, and pasting properties of all starch types differed due to the modification method. Shear stress of mayonnaise was fitted to the Casson and Herschel-Bulkley model, respectively. As partial fat replacers, ANN-modified starch and OSA-starch at 30%, and CA-starch at 30% and 50% showed high yield stress. The elastic moduli (G') of fat-reduced mayonnaises were lower than FF, but mayonnaise with ANN, OSA, and CA showed higher G' than other modified starches. Fat-reduced mayonnaises displayed higher emulsion stability than the FF, especially those with ANN-modified starch, OSA-starch, and CA-starch. In principal component (PC) analysis, groups with high and low emulsion stability were divided by PC1. Overall, ANN-, OSA-, and CA-modified starches were identified as suitable fat replacers in mayonnaise.

Carbohydrates as Fat Replacers

The overconsumption of dietary fat contributes to various chronic diseases, which encourages attempts to develop and consume low-fat foods. Simple fat reduction causes quality losses that impede the acceptance of foods. Fat replacers are utilized to minimize the quality deterioration after fat reduction or removal to achieve low-calorie, low-fat claims. In this review, the forms of fats and their functions in contributing to food textural and sensory qualities are discussed in various food systems. The connections between fat reduction and quality loss are described in order to clarify the rationales of fat replacement. Carbohydrate fat replacers usually have low calorie density and provide gelling, thickening, stabilizing, and other texture-modifying properties. In this review, carbohydrates, including starches, maltodextrins, polydextrose, gums, and fibers, are discussed with regard to their interactions with other components in foods as well as their performances as fat replacers in various systems.

Effect of fish gelatin-gum arabic interactions on structural and functional properties of concentrated emulsions

Concentrated emulsions containing both proteins and polysaccharides are the basis for many commercial products; however, the effects of protein-polysaccharide interactions on the functional properties of these complex systems are often poorly understood from a fundamental standpoint. Hence, the objective of this study was to determine the effects of fish gelatin (FG)-gum arabic (GA) complexation at different aqueous phase pH (3.6, 5.0, and 9.0) on concentrated emulsion structure-function relationships. Concentrated emulsions were prepared using FG-GA mixtures and characterized by rheometry and confocal scanning laser microscopy (CSLM). CSLM images showed that all samples were O/W emulsions; emulsions with lower pH showed smaller oil droplets, greater homogeneity in size distribution, and higher stability. This was attributed to an increased number of FG-GA complexes in the emulsification. Electrostatic attractive interactions and charge neutralization created biopolymer associations with increased emulsification capacity. Samples with FG-GA mixtures at lower pH showed higher elastic moduli under small deformation and exhibited greater deviation between apparent and complex viscosities under the Cox-Merz rule, indicating increased gel network extension and greater intermolecular connectivity between adsorbed layers of adjacent oil droplets. These results can be used to incorporate protein-polysaccharide complexes as a suitable emulsifier in materials comprising concentrated emulsions.

Rheology, particle-size distribution, and stability of low-fat mayonnaise produced via double emulsions

In this study, the effects of the double emulsification method on the rheological properties, particle size, and stability of low-fat mayonnaise were studied. Different water-phase-to-oil ratios (2:8 and 4:6) of primary emulsions and different stabilizer types (sodium caseinate, xanthan gum, and lecithin-whey protein concentrate) were used to produce double-emulsified mayonnaise. As a control sample, mayonnaise was prepared conventionally. Sodium caseinate was found to be the most efficient stabilizer. In the presence of sodium caseinate, the stability and apparent viscosity of double-emulsified mayonnaise increased but their particle sizes decreased. It was found that flow behavior of double-emulsified and conventionally prepared mayonnaise could be described by the power law model. The double-emulsified mayonnaise samples were not different from the control samples in terms of stability and particle size. In addition, using the double emulsion method, it was possible to reduce the oil content of mayonnaise to 36.6%.

Enzyme-enabled responsive surfaces for anti-contamination materials

Many real-life stains have origins from biological matters including proteins, lipids, and carbohydrates that act as gluing agents binding along with other particulates or microbes to exposed surfaces of automobiles, furniture, and fabrics. Mimicking naturally occurring self-defensive processes, we demonstrate in this work that a solid surface carrying partially exposed enzyme granules protected the surface in situ from contamination by biological stains and fingerprints. Attributed to the activities of enzymes which can be made compatible with a wide range of materials, such anti-contamination and self-cleaning functionalities are highly selective and efficient toward sticky chemicals. This observation promises a new mechanism in developing smart materials with desired anti-microbial, self-reporting, self-cleaning, or self-healing functions.