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

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

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

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

Heat transfer in food processing - recent developments and applications

Heat transfer is one of the most important and most common engineering disciplines in food processing. There are many unit operations in the food industry where steady or unsteady state heat transfer is taking place. These operations are of primary importance and affect the design of equipment as well as safety, nutritional and sensory aspects of the product. The chapters in this book deal mainly with: heat transfer applications; methods that have considerable physical property variations with temperature; methods not yet widely spread in the food industry; or methods that are less developed in the food engineering literature. The application of numerical methods has received special attention with a separate chapter as well as emphasis in almost every chapter. A chapter on artificial neural networks (ANN) has also been included since ANN is a promising alternative tool to conventional methods for modelling, optimization, etc in cases where a clear relationship between the variables is not known, or the system is too complex to be modelled with conventional mathematical methods