Comparing different commercial fenugreek galactomannans for the production of emulsions with high intensity sonication. Effect on physical stability and rheological properties.

Galactomannans are considered very effective thickening agents and stabilizers for the food industry. Moreover, guar, locust bean and fenugreek gum present emulsification activity that depends on molecular weight and the mannose/galactose ratio (M/G). In addition, fenugreek gum is known to form a relatively thick layer on the oil interface and is able to produce emulsions with a much smaller droplet size in comparison to various other gums. This ability is often related to the presence of residual protein, depending the removal method enzymatic or chemical. From a dietary point of view, the viscous property has been proved to reduce in vitro the absorption of glucose and the plasma levels of triglycerides and cholesterol in vivo

Influence of Ultrasonication Parameters on Physical Characteristics of Olive Oil Model Emulsions Containing Xanthan

Ultrasonic emulsification of 20-wt.% o/w emulsions (pH 3.8) containing a food-grade emulsifier (whey protein isolate, WPI, 2.7 wt.%) and xanthan gum (XG, 0.25 wt.%) was performed. Time and amplitude of ultrasonic treatment changed in order to evaluate their influence on emulsion droplet size, viscosity, and stability (by multiple light scattering (MLS) profiles) during cold storage (10 days at 5 °C). Ultrasonic treatment duration changed from 1 to 4 min at constant amplitude of 70 %. Considering the amplitude, intervals of 40, 60, 80, and 100 % were chosen, for a constant time of 1 min. Similarly, time and amplitude conditions were used to treat solutions of XG of 1 wt.% and evaluate their influence on viscosity and how that was related to the stability of the emulsion. Increase in sonication time from 1 to 4 min led to a significant oil droplet size decrease from 1.14 to 0.89 μm (median droplet diameter). The viscosity of emulsions and XG solutions was highly influenced and considerably decreased with sonication time applied. At those conditions, an increase of backscattering was observed from 58.9 to 72.7 % after 10 days of storage, meaning that more stable emulsions, thinner and of smaller oil droplet size were produced. A similar trend was observed when the amplitude was increased, but droplet size and creaming were always greater than those noticed by changing the sonication time. However, the rate of viscosity, droplet size, and stability change was greater by increasing the amplitude rather than by changing the sonication time. © 2014 Springer Science+Business Media New York

The effect of olive oil and fenugreek gum content on the stability and oxidation of o/w macro-and submicron-nanoemulsions

Within the last few years numerous polysaccharide extracts have been proposed as emulsion stabilizing agents. This increased interest arises from the fact that commonly used food polysaccharides like guar gum are used in non-food applications, mainly in petroleum refining and pharmaceuticals(Vaughnaetal). Along with the lower global production this has resulted in price fluctuations, consequently severe price increase and supply shortage(Bahamdanetal, Baratietal, Anonetal). From a dietary point of view, the viscous property of fenugreek gum (Trigonella foenum graecum L.)has been proved to reduce in vitro the absorption of glucose and the plasma levels of triglycerides and cholesterol in vivo and could be used when designing low - at emulsified products. Ultrasonic emulsification is a cost effective technique and the interest for scale- up is increasing,as it is considered a “Green Processing” technology for the manufacture of nanoemulsions

Ultrasonic energy input influence on the production of sub-micron o/w emulsions containing whey protein and common stabilizers

Ultrasonication may be a cost-effective emulsion formation technique, but its impact on emulsion final structure and droplet size needs to be further investigated. Olive oil emulsions (20 wt%) were formulated (pH 7) using whey protein (3 wt%), three kinds of hydrocolloids (0.1–0.5 wt%) and two different emulsification energy inputs (single- and two-stage, methods A and B, respectively). Formula and energy input effects on emulsion performance are discussed. Emulsions stability was evaluated over a 10-day storage period at 5 C recording the turbidity profiles of the emulsions. Optical micrographs, droplet size and viscosity values were also obtained. A differential scanning calorimetric (DSC) multiple cool–heat cyclic method (40 to 40 C) was performed to examine stability via crystallization phenomena of the dispersed phase. Ultrasonication energy input duplication from 11 kJ to 25 kJ (method B) resulted in stable emulsions production (reduction of back scattering values, dBS 1% after 10 days of storage) at 0.5 wt% concentration of any of the stabilizers used. At lower gum amount samples became unstable due to depletion flocculation phenomena, regardless of emulsification energy input used. High energy input during ultrasonic emulsification also resulted in sub-micron oil-droplets emulsions (D50 = 0.615 lm compared to D50 = 1.3 lm using method A) with narrower particle size distribution and in viscosity reduction. DSC experiments revealed no presence of bulk oil formation, suggesting stability for XG 0.5 wt% emulsions prepared by both methods. Reduced enthalpy values found when method B was applied suggesting structural modifications produced by extensive ultrasonication. Change of ultrasonication conditions results in significant changes of oil droplet size and stability of the produced emulsions

Effect of screenhouse cover optical properties on sweet pepper fruit quality

The effects of cover optical properties and screenhouse radiative environment on sweet pepper fruit quality and productivity were investigated in a Mediterranean climate (Eastern Greece) under two covering materials (i) a pearl insect-proof screen (IP-78) and (ii) a white insect proof screen (IP-59) with values of the transmittance to solar radiation measured in the field of 78 and 59%, respectively. Sweet pepper plants (Capsicum annuum) were grown under open field (control) and under the above mentioned screens and the microclimate parameters along with fruit production and quality characteristic were measured during a spring-autumn crop circle. The screenhouse microclimate parameters were similar to those measured outside but the radiative environment was significantly different between the three cases. Concerning the fruit quality characteristics, compared to open field, fruits under screens had lower fruit lightness and titratable acidity, higher chroma, fruit weight and volume, and total soluble solids. The effects of screens were most pronounced on early-season-harvested fruits. Significant interactions were obtained between shading and harvest date. The results indicate that compared to open field, screens were able to maintain pepper fruit quality throughout the harvesting period, especially on early-season, where open field climate conditions (solar radiation and fruit temperature levels) induced severe crop stress conditions. © 2017 ISHS

Physical characteristics of submicron emulsions upon partial displacement of whey protein by a small molecular weight surfactant and pectin addition

O/W emulsions (6% wt olive oil) were prepared at pH 3.3 using different WPI:Tween 20 weight ratios (1:0, 3:1, 1:1, 1:3, 0:1) at 1% wt total concentration. The emulsion droplet size was found to decrease with an increase in Tween 20. A minimum droplet size of d3,2 300 nm was found for Tween systems alone, similar to that found (360 nm) for a 1:1 WPI:Tween 20 combination (p <0.05). This specific composition showed a value for the interfacial tension close to that of Tween 20 alone. However, the emulsions presented low stability regardless of the WPI:Tween 20 ratio. To increase their stability, pectin was added, in various concentrations (0.2, 0.4 and 0.6% wt), using the Layer by Layer technique. In the presence of pectin, the ¿-potential of the oil droplets became negative; indicating that negatively charged pectin was absorbed onto the positively-charged droplet surface forming a secondary layer. The additional layer resulted in a wide range of emulsion stability. For all pectin concentrations, the 1:1 ratio of WPI:Tween 20 showed the highest stability. In most emulsions, extensive aggregation of oil droplets was observed, and their viscosity increased. Insufficient amounts of pectin to form the secondary layers led to bridging flocculation phenomena of oppositely charged pectin and proteins, leading to aggregation of the oil droplets. The higher the concentration of pectin, the greater the stability of the emulsion due to higher viscosity. All in all, the addition of a second layer consisting of pectin can be used to increase the stability of an emulsion containing emulsion droplets in the sub-micron range

Influence of ultrasonication parameters and NaCΙ on the stability of olive oil model emulsions containing xanthan

The purpose of this study was to investigate the effect of ultrasound parameters such as time and amplitude on the stability of emulsions containing a commonly used biopolymer stabilizer and provide useful information about process optimization and over-processing conditions. Finally the influence of NaCL addition (100, 200, 300, 400 mM) on emulsion stability is presented

Encapsulation of Moringa oleifera Extract in Ca-Alginate Chocolate Beads: Physical and Antioxidant Properties

The aim of the present study was to evaluate the physical and antioxidant properties of chocolate alginate beads containing Moringa oleifera leaf extract (MLE) produced with ecofriendly solvent extraction technology (Deep Eutectic Solvents). The concentration of MLE incorporated was 0, 2, 4, and 6% w/w, and hardening time for ionotropic gelation with CaCl2 solution was 2, 8, or 20 min. Freshly prepared beads were evaluated for their geometric (area, perimeter, ferret diameter, circularity, roundness), color (CIE L∗, a∗, and b∗ and chroma), and antioxidant properties (total phenolic content and percentage inhibition of DPPH• radical). Increasing the MLE concentration resulted in beads smaller in size and more spherical, whereas hardening time only affected their circularity. MLE concentration had also a profound effect on color and antioxidant properties of the beads. As the concentration of MLE increased, the beads appeared lighter and their chroma increased. The radical scavenging activity was ameliorated by the MLE concentration increase for samples hardened for 8 and 20 min, whereas it was unaffected for those at 2 min. The hardening time on the contrary did not affect the inhibition of DPPH• values, regardless of the amount of extract added. © 2021 Olga Kaltsa et al

Fortification of chocolate using Moringa oleifera extract encapsulated in microemulsions

The aim of the present study was to evaluate the physical and antioxidant properties of microemulsions containing Moringa oleifera leaf extract (MLE) produced by the means of a deep eutectic solvent. Selected microemulsions containing MLE were incorporated in chocolate products to enrich them. Their color properties including CIE L∗, a∗, b∗ parameters and whitening index (WI) along with DPPH radical scavenging activity were assessed during a period of 8 months. The antioxidant activity of microemulsions depended on the oil phase used, while it was unaffected by the concentration of MLE. Samples prepared with soybean oil as oil phase containing MLE presented the highest radical inhibition percentage (I% = 26.8-27.8%). Coconut microemulsions were finally incorporated at 2 and 4% w/w concentration into chocolate products, as coconut oil is a known cocoa butter substitute. Although the incorporation of MLE microemulsions did not affect the color properties of most of the chocolates, enriched products did not exhibit superior antioxidant activity compared to control samples. © O. Kaltsa