Influence of primary homogenization step on microfluidized emulsions formulated with thyme oil and Appyclean 6548

Effects of Microfluidization on the Physical and Storage Stability of Walnut Protein Emulsion and Beverages

Walnut meal is a by-product produced during the production of walnut oil and is often treated as a waste. However, the nutrients in walnut meal mean it has significant potential for development as a plant-based milk. This study investigated the effect of microfluidization on the stability of walnut protein emulsion (WPE) and walnut protein beverage (WPB) produced from walnut meal, compared with conventional homogenization. The particle size, zeta potential, rheological properties, and stability of WPE all significantly improved after microfluidization. The mean particle size and zeta potential of the microfluidized WPE significantly decreased (p < 0.05). The rheological properties demonstrated that the viscosity of the microfluidized WPE decreased by 80%, and that the shear force increased 4.5 times as the shear rate increased. This gave the resulting product the characteristics of non-Newtonian fluid. LUMisizer stability demonstrated that microfluidization improves stability through protein absorption on the oil-water interface. Microfluidization increased the denaturation temperature (Tm) of WPE from 135.65 to 154.87℃. Moreover, microfluidization improved the color, centrifugal precipitation rate, and viscosity in WPB compared to the control at all studied temperatures. The Arrhenius approach was used to establish a shelf-life model, which predicted that microfluidized WPB could be stored for 175 d at 4℃. This study provided a new reference for the widespread application of microfluidization in the production of food-based emulsion and beverage products.

Mechanism study on the formation of complex between Ca(II) and indigo carmine for potential food use as a colorant lake

This study elucidated the formation mechanism of calcium-indigo carmine (IC) complex. Parameters of the complex, such as Turbiscan stability index (TSI), yield and stoichiometric ratio (Ca to IC) were investigated. Isothermal titration calorimetry (ITC), UV/Visible spectrophotometry, infrared spectroscopy and Raman spectroscopy were used to explore the interaction between IC and Ca(II) during formation reaction and in the powdered lake. The TSI analysis and yield test suggested pH 7.0 as the most suitable pH to produce this complex. The conjugation between IC and Ca(II) was an exothermal reaction with increase of entropy (ΔH = -0.728 ± 0.11 kJ·mol^-1 and ΔS = 66.55 ± 1.89 kJ·mol^-1·K^-1 at 25 °C). Both ITC and stoichiometric ratio test suggested one Ca atom tended to conjugate five IC molecules at ambient temperature when an adequate amount of Ca(II) appeared. Spectrometry techniques suggested that the sulfonic acid groups in IC formed coordination bonds with the Ca to construct the complex.

Processing and Formulation Optimization of Mandarin Essential Oil-Loaded Emulsions Developed by Microfluidization

Emulsions can be used as delivery systems for bioactive ingredients for their incorporation in food products. Essential oils are natural compounds found in plants that present antioxidant and antimicrobial activity. Therefore, the main goal of this work was to develop emulsions, containing mandarin essential oil stabilized by two food-grade surfactants and guar gum, and to evaluate their physical stability. The initial droplet size of emulsions developed by microfluidization was optimized, obtaining diameters below one micron regardless of the processing conditions. However, the emulsion processed at 25,000 psi and one pass exhibited the lowest mean droplet sizes and polidispersity, and therefore, a higher stability. Different ratios of Tween 80 and Span 80 were assessed as stabilizers. Results obtained indicated that the ratio of surfactants had a significant effect on the mean droplet sizes, physical stability, and rheological properties. Thus, we found that the optimum ratio of surfactants was 75/25 (Tween80/Span80) on account of the lowest droplet mean diameters, lack of coalescence, and a low creaming rate. The rheological characterization of the stable emulsions showed a shear thinning flow behavior, and G″ (loss modulus) values higher than G′ (storage modulus) values, in all the frequency range. The rheological behavior may be governed by the guar gum, which was confirmed by field emission scanning electron microscopy (FESEM). This research can be considered as the starting point for future applications of mandarin essential oil in emulsions, which can be incorporated in products as food preservatives.

Characterization of novel nanoemulsions, with improved properties, based on rosemary essential oil and biopolymers

BACKGROUND

Nowadays, it is of great interest to develop stable and sustainable formulations that act as nanocarriers of active ingredients. In this work, the droplet size distribution, rheology and physical stability of nanoemulsions with improved properties containing rosemary essential oil and biopolymers as a function of the concentration of these polysaccharides were investigated.

RESULTS

Mean diameters below 150 nm were achieved, indicating nanostructures were obtained. Regardless of gum type, a gel-like structure and a shear thinning behaviour was achieved. In addition, an increase of G', G″ and viscosity and a decrease of J₀ , J₁ , J₂ , λ₁ and λ₂ with increasing gum concentration were observed, due to the formation of a three-dimensional network in the aqueous phase. Slight differences between nanoemulsions containing welan or xanthan were found. Creaming, depletion flocculation and gel aggregation were the main destabilization processes at low, intermediate and high gum concentration, respectively. A 0.4 wt% gum nanoemulsion exhibited the best physical stability.

CONCLUSION

These stable and sustainable nanoemulsions with improved rheological properties contribute to the development of biodegradable and non-toxic food or agrochemical products. © 2020 Society of Chemical Industry.

Structure and stability of W1/O/W2 emulsions as influenced by WPC and NaCl in inner aqueous phase

Effect of WPC and NaCl in internal aqueous phase (W₁) of W₁/O/W₂ type double emulsions was studied. Pre-emulsion and final emulsion were prepared using microfluidizer and Ultra-Turrax high shear mixer, respectively. The emulsions prepared using salt exhibited uniform droplet size distribution and structural integrity. WPC at 6% and NaCl at 2 or 4% levels demonstrated better sedimentation stability (> 99%) and encapsulation stability (> 95%) during preparation and storage of double emulsions. Samples without added NaCl showed poor emulsion stability and structural integrity. Higher level of WPC i.e. 8% resulted in poor stability and encapsulation efficiency of double emulsions at all salt levels. Combined use of optimum levels of WPC and NaCl along with processing interventions resulted in stable double emulsions even after storage at room temperature for 10 days. This study highlights the fact that structural integrity of internal aqueous phase (W₁) depends upon presence of osmotic agent i.e. salt and stabilising proteins i.e. WPC.

Strategies for reducing Ostwald ripening phenomenon in nanoemulsions based on thyme essential oil

BACKGROUND

White thyme essential oil, which can be incorporated in clean-label and food emulsion-based products, is a natural antimicrobial agent. However, emulsions containing essential oils commonly undergo Ostwald ripening as the main destabilization process. The main objective of this work was to evaluate various strategies for the inhibition of Ostwald ripening so as to develop stable nanoemulsions containing white thyme essential oil as food preservative and Kolliphor EL as surfactant.

RESULTS

In a first approach, the influence of the surfactant/dispersed phase ratio and the number of cycles through a microfluidizer on droplet size distribution was evaluated. Unfortunately, these emulsions underwent Ostwald ripening, which was demonstrated by the application of the Lifshitz-Slyozov-Wagner theory. In order to reduce this destabilization mechanism, two different techniques based on the modification of the formulation (addition of rosin gum or Aerosil COK84) were analysed using laser diffraction and multiple light scattering techniques. The addition of rosin gum inhibited the Ostwald ripening mechanism, but only partially. Conversely, the incorporation of Aerosil COK84 to the continuous phase led to a gel-like rheological behaviour which seemed to practically avoid Ostwald ripening.

CONCLUSIONS

Aerosil particles cover the droplets and form a three-dimensional network suggesting a Pickering stabilization, which was confirmed using transmission electronic microscopy. The results confirmed the role of Aerosil COK84, not only as a thickener or gelling agent, but also as an Ostwald ripening inhibitor. © 2019 Society of Chemical Industry.