Effect of olive mill wastewater phenolic extract, whey protein isolate and xanthan gum on the behaviour of olive O/W emulsions using response surface methodology

Physical stability, microstructure and interfacial properties of solid-oil-in-water (S/O/W) emulsions stabilized by sodium caseinate/xanthan gum complexes

Calcium carbonate (CaCO₃) has poor suspension stability, which severely limits its application in food processing and products. In this study, sodium caseinate (NaCas) and sodium caseinate (NaCas)-xanthan gum (XG) mixtures were compared for the stable preparation of solid/oil/water (S/O/W) emulsions for the delivery of calcium carbonate (CaCO₃) to solve the problem of poor suspension stability. The physical stability, particle size distribution, and microstructure of S/O/W emulsions were investigated to prove the successful construction of the system. The dynamic surface pressure and surface swelling properties of 2.0 wt% NaCas with different concentrations of XG were investigated to clarify the effect of interfacial properties of NaCas-XG mixtures on the emulsion stability of S/O/W emulsions. The results showed that the addition of XG resulted in enhanced physical stability, reduced particle size distribution, and enhanced encapsulation effect of the emulsion, forming a more three-dimensional core-shell structure via dendritic links. XG had a significant effect on the dynamic properties of the NaCas adsorption membrane: NaCas interacted with XG and the diffusion (k_diff) of NaCas to the interface decreased in short adsorption time, thus limiting the protein adsorption effectiveness; the presence of XG reduced the penetration (k_P) and rearrangement (k_R) rates at the interface during long adsorption times. Meanwhile, the NaCas-XG mixture has a high swelling elasticity. The results of this study can be used to improve the quality of related emulsion products or to prepare delivery systems for bioactive compounds.

Encapsulation of calcium carbonate with a ternary mixture of sodium caseinate/gelatin/xanthan gum to enhance the dispersion stability of solid/oil/water emulsions

Calcium carbonate (CaCO3) has poor suspension stability, which severely limits its application in food processing and products. The solid/oil/water (S/O/W) emulsion stabilized by sodium caseinate (NaCas), gelatin (GEL), and xanthan gum (XG) ternary composite was to improve the dispersion stability of CaCO3 in emulsions. Particle size, Zeta potential, physical stability, and microstructure were determined to characteristic the stability of the S/O/W emulsions. Shear rheological and tribological analyses were used to characterize the rheological properties of S/O/W emulsions. X-ray diffraction (XRD), Infrared spectral analysis (FTIR), and molecular docking were used to characterize the molecular interactions, which was to explore the influence of the W phase on the system stability. It was found that when the NaCas concentration was 2 wt% and the S/O phase addition was 5%, the particle size distribution was uniform, and the physical stability was improved. CLSM and Cryo-SEM results showed that the S/O/W emulsions could embedded CaCO3 in the system, and formed a dense three-dimensional network space structure. The viscosity of the system increased and even agglomeration occurred with NaCas concentration increased, and the stability of the emulsion decreased. XRD results confirmed that the CaCO3 was partially covered due to physical embedding. Infrared spectral analysis and molecular docking results showed electrostatic, hydrophobic interaction, and hydrogen bond interaction between NaCas, GEL, and XG, which could improve the stability of S/O/W emulsions. The results showed that the S/O/W emulsions delivery system is an effective way to promote the application of CaCO3.

Macro-Batch and Continuously Operated Microfluidic Emulsification—Differences, Similarities and Optimization

In this work, the emulsification of oil-in-water two-phase systems with three emulsifiers (PEG1500, 6000 and 20000) was studied in a batch macro system and in a continuously operated microfluidic system. The effect of emulsifier concentration, oil concentration and mixing rate on zeta potential and average Feret diameter was analyzed for the macro-batch system, while the effect of emulsifier concentration, oil concentration and total flow rate on zeta potential and average Feret diameter was analyzed for the microfluidic system. The emulsions prepared in batch system were more stable, had smaller droplet diameter but higher values of polydispersity index (PDI) compared to those prepared by continuous method. In both cases, batch and continuous, the use of PEG with higher molecular weight resulted in emulsions with lower zeta potential values. In batch emulsification, all three optimization parameters (emulsifier concentration, oil concentration and mixing rate) had a significant influence on the average Feret diameter and zeta potential (depending on the PEG, used for emulsification), while the emulsifier concentration had the most significant influence on the zeta potential and average Feret diameter of emulsions prepared in the continuous microsystem process.

State of knowledge on chemical, biological and nutritional properties of olive mill wastewater

The Mediterranean olive oil industries are producing annually a massive quantity of olive mill wastewater (OMWW). Unfortunately, the OMWW is released arbitrarily in the nature without any pretreatment. Thus, it exhibits a high toxicity against the whole natural ecosystem including, microorganisms, plants and animals. In order to eliminate or reduce its pollution, OMWW must be properly treated prior to its release in the nature. In this regard, different treatment methods have been developed by researchers, but some of them were costly and others were inappropriate. Thus, more efforts should be made to save the nature from this pollutant. In the light of that, the current work summaries the state of knowledge regarding the OMWW from a chemical, biological, nutraceutical point of view, and the treatment methods that were used to eliminate its risk of pollution.

Preparation of Water-in-Oil Nanoemulsions Loaded with Phenolic-Rich Olive Cake Extract Using Response Surface Methodology Approach

In this study, we aimed to prepare stable water-in-oil (W/O) nanoemulsions loaded with a phenolic-rich aqueous phase from olive cake extract by applying the response surface methodology and using two methods: rotor-stator mixing and ultrasonic homogenization. The optimal nanoemulsion formulation was 7.4% (w/w) of olive cake extract as the dispersed phase, and 11.2% (w/w) of a surfactant mixture of polyglycerol polyricinoleate (97%) and Tween 80 (3%) in Miglyol oil as the continuous phase. Optimum results were obtained by ultrasonication for 15 min at 20% amplitude, yielding W/O nanoemulsion droplets of 104.9 ± 6.7 nm in diameter and with a polydispersity index (PDI) of 0.156 ± 0.085. Furthermore, an optimal nanoemulsion with a droplet size of 105.8 ± 10.3 nm and a PDI of 0.255 ± 0.045 was prepared using a rotor-stator mixer for 10.1 min at 20,000 rpm. High levels of retention of antioxidant activity (90.2%) and phenolics (83.1-87.2%) were reached after 30 days of storage at room temperature. Both W/O nanoemulsions showed good physical stability during this storage period.

Sago starch nanocrystal-stabilized Pickering emulsions: Stability and rheological behavior

This study presents the isolation of SNC from sago starch and its performance as proficient particle emulsifier. It highlights the impact of SNC on the stability and rheological properties of oil-in-water (o/w) emulsions. The percentage yield of the SNC obtained was equivalent to 25 ± 0.1% (w/w) with particle diameters ranging from 25 to 100 nm. A series of Pickering emulsion at different ratios of oil (5%-35% v/v) and SNC (1%-4% w/v) was prepared for further investigations. The mean droplet diameter of emulsions obtained was ranged from 19.12 to 35.96 μm, confirming the effects of both SNC and oil content on the droplet's diameter distribution. Formulations with 4.0 wt% of SNC exhibited the maximum stability against coalescence. Results obtained have justified that the SNC can be used as an alternative solid emulsifier in producing stable emulsion with desired properties for various applications.

Physicochemical properties, oxidative stability and antioxidant capacity of clean label meat-based sauces: effects of phenolic extracts addition and cold storage

Physicochemical properties, oxidative stability and antioxidant capacity (AC) of clean label meat-based sauces (MBSs) were investigated with reference to cold storage time (ST) and addition of phenolic extracts (PEs): green coffee bean (GCE), green tea (GTE), knotweed rhizome (KRE). All parameters determined were compared to a control sample (CS), prepared without extracts. MBSs enriched with GCE or KRE were stable during the whole ST (90 days), while the CS and samples containing GTE, showed descending trend regarding physical stability after 10 days of storage. MBSs prepared with PEs (90 days storage) demonstrated: peroxide value (PV) < 8.5 mEq O₂/kg lipids, TBARS < 5.6 mg MDA/kg lipids, carbonyl content < 4.7 nmol/mg protein, and the values were significantly (p < 0.05) smaller than those found in CS. Irrespectively of the applied measurements (ABTS, DPPH, FRAP) the values of AC (trolox equivalent, TE) decreased with ST, and regarding ABTS assay were in ranges: 0.73–0.42 mM TE (CS), 3.54–2.75 mM TE (GCE), 4.89–3.29 mM TE (GTE) and 3.86–2.25 mM TE (KRE). ANOVA revealed that rheological parameters obtained from Herschel–Bulkley′s and Bohlin′s models were predominantly (p < 0.001) affected by ST. After 90 days of storage, values of the desirability index were significantly (p < 0.05) higher for GCE-fortified MBS than for samples prepared with GTE and KRE. The results of this study can be useful to optimize composition of meat-based sauces containing bioactive ingredients and exhibiting desired by the consumer sensory features.

Concentrated O/W emulsions formulated by binary and ternary mixtures of sodium caseinate, xanthan and guar gums: rheological properties, microstructure, and stability

The effects of xanthan gum (XG) (0, 0.3, 0.6 wt%), guar gum (GG) (0, 0.3, 0.6 wt%) and XG:GG mixtures (0.3-0.3, 0.3-0.6, 0.6-0.3 and 0.6-0.6 wt%) on the physical stability of sodium caseinate (CN) stabilized concentrated O/W emulsions (φoil = 0.6) were examined. The emulsion stability, microstructure, droplets size distribution, and rheological properties were evaluated. The findings showed that with increasing total gum concentration up to 0.6% droplets size and emulsion instability significantly decreased (p < 0.05). The emulsion containing a ternary mixture of CN:XG:GG at total gum concentration (0.6%) with a mixing ratio of 0.3:0.3 XG:GG exhibited the best stability with the highest ESI value (98.3%). Above the critical concentration, an excessive increase in storage modulus led to a significant increase in droplet size and emulsion instability. In brief, concentrated emulsions stabilized by binary and ternary mixtures (CN/XG/GG) may be applicable in special food like heavy cream and as a template for fabricating oleogels.

Improving Stability and Accessibility of Quercetin in Olive Oil-in-Soy Protein Isolate/Pectin Stabilized O/W Emulsion

Herein we report a soy protein isolate/pectin binary complex particle to stabilize emulsion (olive oil served as dispersed phase) containing quercetin. FTIR was conducted to confirm successful preparation of emulsion before and after embedding quercetin. CLSM was used to determine the microstructure and zeta-potential, rheological behavior, storage stability and freeze-thaw stability were analyzed and were correlated with pH condition. Olive oil-soy protein isolate/pectin emulsion at pH 3.0 can remain stable after 30 days’ storage and exhibited greatest freeze-thaw stability after 3 cycles. Quercetin availability was evaluated by in vitro gastrointestinal digestion experiments and it reached 15.94% at pH 7.0.

A Polyphenolic Extract from Olive Mill Wastewaters Encapsulated in Whey Protein and Maltodextrin Exerts Antioxidant Activity in Endothelial Cells

The aim of the present study was to compare maltodextrin and whey protein as encapsulation carriers for olive mill wastewater (OMWW) phenolic extract for producing antioxidant powder, by using spray drying under 17 different conditions. In some samples, gelatin was also added in the encapsulation mixture. The antioxidant activity was assessed in vitro by using the DPPH^•, ABTS^•+, reducing power and DNA plasmid strand breakage assays. The results showed that both materials were equally effective for producing antioxidant powder, although by using different conditions. For example, inlet/outlet temperature of the spray drying did not seem to affect the maltodextrin samples’ antioxidant activity, but whey protein samples showed better antioxidant activity at lower temperatures. Gelatin use decreased antioxidant activity, especially in whey protein samples. The two most potent samples, one encapsulated in maltodextrin and the other in whey protein, were examined for their antioxidant effects in human endothelial cells by assessing glutathione (GSH) and reactive oxygen species (ROS) levels. Both samples significantly enhanced the antioxidant molecule of GSH, while maltodextrin sample also decreased ROS. The present findings suggested both materials for encapsulation of OMWW extract for producing antioxidant powder which may be used in food products, especially for the protection from ROS-induced endothelium pathologies.

Studies on eggless mayonnaise from rice bran and sesame oils

Mayonnaise was prepared by replacing refined sunflower oil with physically refined rice bran oil (RBO), filtered sesame oil (SO) and blends of both RBO:SO. Emulsions were formulated using xanthan gum as a replacer for egg. The effect of replacing xanthan gum on varying oil blends (RBO:SO) on the physicochemical properties such as texture (consistency), stability, viscosity, and bioactives (oryzanol and sesamol content) were also studied. Significant differences were observed in the fat content of the emulsions prepared. Xanthan gum based mayonnaise's had 63-65% fat, whereas control sample with egg had 78% fat. The spreadability ranged between 1.2 and 1.6 N and stability of these spreads was found to be better than that of control. Mayonnaise with the desired colour, optimum spreadability and excellent emulsion stability could be prepared using RBO, and blends of RBO:SO. Significant differences were seen in the instrumental consistency and rheological studies among the mayonnaises prepared. The present study focusses on the preparation of a healthy mayonnaise using rice bran and sesame oil and their blends which have beneficial health effects due to the presence of oryzanol and sesamol.

Effect of Emulsifier Type, Maltodextrin, and β-Cyclodextrin on Physical and Oxidative Stability of Oil-In-Water Emulsions

The effect of emulsifiers, emulsion stabilizer (maltodextrin, MD), and β-cyclodextrin (BCD) on physical and oxidative properties of oil-in-water (O/W) emulsions (5%, 20%, 40% of oil, w/w) was investigated. Four different emulsifiers were selected based on their structure: two types of protein-based emulsifiers (sodium caseinate, SC; and whey protein isolate, WPI), and two types low molecular weight emulsifiers (LMEWs: lecithin, LEC; and Citrem, CITREM). Physical and oxidative stability of emulsions prepared with these emulsifiers together with MD were compared based on their creaming index (CI), viscosity, droplet size, zeta potential, peroxide and p-anisidine values. LMWE-stabilized emulsions (with LEC or CITREM) had better creaming stability with lower droplet sizes whereas protein-stabilized emulsions (with SC or WPI) had higher viscosities. Droplet size was the lowest when CITREM was used, which increased with increasing oil concentration for all emulsifiers. Formulation with the lowest CI value and droplet size was considered to be more prone to oxidation; therefore, a 1:1 (w/w) combination of CITREM with BCD was used to stabilize the emulsions to improve the oxidative as well as physical stability. Added BCD significantly increased the storage stability of emulsions by reducing CI and droplet size values with a simultaneous increase in the viscosity, both at room temperature and at storage conditions (at 4 and 55 ^o C). However, the oxidative as well as physical stability of BCD added emulsions were not improved, neither toward heat- nor light-induced lipid oxidation. PRACTICAL APPLICATION: This work investigated the effects of emulsifiers and dextrins on the stability of oil-in-water (O/W) emulsions. Both maltodextrin (MD) and β-cyclodextrin (BCD) addition resulted in enhanced physical stability, the latter being more effective. The findings can be applied to formulate emulsions with improved shelf life within the limits of allowed daily intake (ADI) level of BCD (5 mg/kg bw per day).

Effect of sucrose ester and carboxymethyl cellulose on physical properties of coconut milk

The influence of sucrose ester (SE) and carboxymethyl cellulose (CMC) on the physical properties of coconut milk was determined using response surface methodology based on central composite design. The R 2 of all response variables was more than 0.80 which indicated a high proportion of variability was explained by the model and showed that increasing the amount of SE decreased the droplet size of coconut milk. The viscosity and creaming index were dependent on the SE and CMC concentration. Increasing the SE and CMC concentration increased viscosity but creaming index was decreased. The results suggested that suitable amount of SE and CMC should be specified in order to obtain a high quality of coconut milk products.

High-Throughput Optofluidic Acquisition of Microdroplets in Microfluidic Systems

Droplet optofluidics technology aims at manipulating the tiny volume of fluids confined in micro-droplets with light, while exploiting their interaction to create "digital" micro-systems with highly significant scientific and technological interests. Manipulating droplets with light is particularly attractive since the latter provides wavelength and intensity tunability, as well as high temporal and spatial resolution. In this review study, we focus mainly on recent methods developed in order to monitor real-time analysis of droplet size and size distribution, active merging of microdroplets using light, or to use microdroplets as optical probes.

Use of phenolic compounds from olive mill wastewater as valuable ingredients for functional foods

Olive mill wastewater (OMW) is a pollutant by-product from the virgin olive oil production. Its high content in phenolic compounds makes them play an important role for their use in foods, for their high antioxidant significance. The present paper gives an overview on the techniques for OMW valuable ingredient separation, focusing on the most effective ones for their use in food products as functional ingredients. We report on effective methods to recover OMW phenolics, and give several examples on the use these extracts in foods. When added into vegetable oils, their effect on retarding lipid oxidation improves the oxidative status of the product, whilst several challenges need to be faced. OMW phenolic extracts were also used in food emulsions, milk products or other model systems, showing promising results and little or no negative impact on the sensory characteristics or other properties. Their possible use as antimicrobial agents is also another promising approach, as positive results were obtained when applied in meat products. Other examples of using natural phenolic extracts from other sources are suggested also for OMW extracts, to expand their use and thus to improve the nutritional and technological quality of foods.

Development of Phenol-Enriched Olive Oil with Phenolic Compounds Extracted from Wastewater Produced by Physical Refining

While in the last few years the use of olive cake and mill wastewater as natural sources of phenolic compounds has been widely considered and several studies have focused on the development of new extraction methods and on the production of functional foods enriched with natural antioxidants, no data has been available on the production of a phenol-enriched refined olive oil with its own phenolic compounds extracted from wastewater produced during physical refining. In this study; we aimed to: (i) verify the effectiveness of a multi-step extraction process to recover the high-added-value phenolic compounds contained in wastewater derived from the preliminary washing degumming step of the physical refining of vegetal oils; (ii) evaluate their potential application for the stabilization of olive oil obtained with refined olive oils; and (iii) evaluate their antioxidant activity in an in vitro model of endothelial cells. The results obtained demonstrate the potential of using the refining wastewater as a source of bioactive compounds to improve the nutraceutical value as well as the antioxidant capacity of commercial olive oils. In the conditions adopted, the phenolic content significantly increased in the prototypes of phenol-enriched olive oils when compared with the control oil.