Ultrasonic studies of the crystallization behavior of two palm fats O/W emulsions and its modification

Applications of ultrasound techniques in tandem with non-destructive approaches for the quality evaluation of edible oils

Edible oils include triglycerides that are extracted from oil seeds or fruits such as sunflowers, palms, olives, soys, rapeseeds, cocoa and many others. They are the elementary origins of unsaturated fats and vitamins especially vitamin 'E' in people's diets. Edible oils are at risk of intentional (such as inadequate storage conditions) and unintentional adulteration, so it is necessary to pay attention to their safety, health and fraud. Generally, this evaluation can be destructive or non-destructive. There are numerous methods to evaluate quality of edible oils which include sensory analysis, chemical analysis, chromatography, ultrasound, etc. The Ultrasonic approach is a non-destructive way and also fast, accurate, inexpensive, repeatable, portable and simple. Combination of ultrasound with other techniques such as electronic nose, electronic tongue, visible spectroscopic fingerprints, chemical descriptors, Raman spectroscopy, mid-infrared and machine vision, will improve quality evaluation and detection accuracy. This review summarizes the ultrasound idea and the latest knowledge of its application with other techniques on evaluation of edible oils.

Reaction Monitoring by Ultrasounds in a Pseudohomogeneous Medium: Triglyceride Ethanolysis for Biodiesel Production

The sound propagation speed measurement us is used for monitoring triglyceride ethanolysis in a broad range of reaction conditions (mainly, temperature: 23–50 °C; ethanol/oil: from 6 to 24 mol/mol). Experimentally, us slightly increased with the reaction time in all cases as a result of the contribution of its dynamic mixture components. Nomoto’s expression for homogeneous mixtures offered suitable us estimation but with values notably higher than the experimental ones due to the resistance to sound propagation offered by the ethanol/oil interphase (non-homogeneous medium). Our strategy was based on both the comparison of the experimental us values and the theoretical ones correlated by means of triglyceride conversion and on the estimation of the sound speed of oil/ethanol that could emulate the resistance offered by the interphase. The evolution of the reactions was predicted quite well for all the experiments carried out with very different reaction rates. Nevertheless, at the beginning of the reaction, the estimated conversion (outside of industrial interests) showed important deviations. The presence of the intermediate reaction products, diglycerides, and monoglycerides could be responsible for those deviations.

Overview of Some Recent Advances in Improving Water and Energy Efficiencies in Food Processing Factories

Rapid development of food factories in both developed and developing countries, owing to continued growth in the world population, plays a critical role in the food supply chain, including environmental issues such as pollution, emissions, energy and water consumption, and thus food system sustainability. The objective of this study was to briefly review various environmental aspects of food processing operations, including aquatic, atmospheric, and solid waste generation, and also to discuss several strategies that many companies are using to reduce these negative impacts as well as to improve water and energy efficiency. To obtain higher energy efficiencies in food processing factories, two key operations can play critical roles: non-thermal processing (e.g., high pressure processing) and membrane processes. For higher water efficiency, reconditioning treatments resulting in water reuse for other purposes can be conducted through chemical and/or physical treatments. With regards to reducing volumes of processing food waste, two approaches include value-added by-product applications (e.g., animal feed) and/or utilization of food waste for energy production. Finally, we present trends for lowering operational costs in food processing.

Nanoencapsulation, Nano-guard for Pesticides: A New Window for Safe Application

The application of nanotechnology in pesticide delivery is relatively new and in the early stages of development. This technology aims to reduce the indiscriminate use of conventional pesticides and ensure their safe application. This critical review investigated the potential of nanotechnology, especially the nanoencapsulation process for pesticide delivery. In-depth investigation of various nanoencapsulation materials and techniques, efficacy of application, and current research trends are also presented. The focus of ongoing research was on the development of a nanoencapsulated pesticide formulation that has slow releasing properties with enhanced solubility, permeability, and stability. These properties are mainly achieved through either protecting the encapsulated active ingredients from premature degradation or increasing their pest control efficacy for a longer period. Nanoencapsulated pesticide formulation is able to reduce the dosage of pesticides and human exposure to them, which is environmentally friendly for crop protection. However, lack of knowledge of the mechanism of synthesis and lack of a cost-benefit analysis of nanoencapsulation materials hindered their application in pesticide delivery. Further investigation of these materials' behavior and their ultimate fate in the environment will help the establishment of a regulatory framework for their commercialization. The review provides fundamental and critical information for researchers and engineers in the field of nanotechnology and especially the use of nanoencapsulation techniques to deliver pesticides.

Fat crystallisation at oil-water interfaces

This review focuses on recent advances in the understanding of lipid crystallisation at or in the vicinity of an interface in emulsified systems and the consequences regarding stability, structure and thermal behaviour. Amphiphilic molecules such as emulsifiers are preferably adsorbed at the interface. Such molecules are known for their ability to interact with triglycerides under certain conditions. In the same manner that inorganic crystals grown on an organic matrix see their nucleation, morphology and structure controlled by the underlying matrix, recent studies report a templating effect linked to the presence of emulsifiers at the oil/water interface. Emulsifiers affect fat crystallisation and fat crystal behaviour in numerous ways, acting as impurities seeding nucleation and, in some cases, retarding or enhancing polymorphic transitions towards more stable forms. This understanding is of crucial importance for the design of stable structures within emulsions, regardless of whether the system is oil or water continuous. In this paper, crystallisation mechanisms are briefly described, as well as recent technical advances that allow the study of crystallisation and crystal forms. Indeed, the study of the interface and of its effect on lipid crystallisation in emulsions has been limited for a long time by the lack of in-situ investigative techniques. This review also highlights reported interfacial effects in food and pharmaceutical emulsion systems. These effects are strongly linked to the presence of emulsifiers at the interface and their effects on crystallisation kinetics, and crystal morphology and stability.

Effect of intramuscular fat content and serving temperature on temporal sensory perception of sliced and vacuum packaged dry-cured ham

The present study aimed to evaluate the influence of three serving temperatures (7 °C, 16 °C and 20 °C) and two different ham sections varying in the intramuscular fat (IMF) content on the sensory characteristics of sliced and vacuum-packaged Iberian dry-cured hams using the time-intensity (TI) method. Preceding the TI study, appearance and odour of dry-cured hams were evaluated using a descriptive profile. Fluidity and brightness of the external fat, brightness of lean and all odour attributes increased as serving temperature increased whereas the hardness of external fat decreased with temperature. Oral temperature would have disguised the effect of serving temperature over time as a consequence of a possible balance between both temperatures during samples' consumption. TI revealed that the effect of serving temperature on flavour and texture perception was more noticeable along the first seconds of chewing. Odour intensities increased with the IMF content and temporal perception of hardness, saltiness and rancid flavour were also significantly influenced by the IMF content.

Crystals and crystallization in oil-in-water emulsions: implications for emulsion-based delivery systems

Many bioactive components intended for oral ingestion (pharmaceuticals and nutraceuticals) are hydrophobic molecules with low water-solubilities and high melting points, which poses considerable challenges to the formulation of oral delivery systems. Oil-in-water emulsions are often suitable vehicles for the encapsulation and delivery of this type of bioactive component. The bioactive component is usually dissolved in a carrier lipid phase by either dilution and/or heating prior to homogenization, and then the carrier lipid and water phases are homogenized to form an emulsion consisting of small oil droplets dispersed in water. The successful development of this kind of emulsion-based delivery system depends on a good understanding of the influence of crystals on the formation, stability, and properties of emulsions. This review article addresses the physicochemical phenomena associated with the encapsulation, retention, crystallization, release, and absorption of hydrophobic bioactive components within emulsions. This knowledge will be useful for the rational formulation of effective emulsion-based delivery systems for oral delivery of crystalline hydrophobic bioactive components in the food, health care, and pharmaceutical industries.

Factors governing partial coalescence in oil-in-water emulsions

The consequences of the instability mechanism partial coalescence in oil-in-water food emulsions show a discrepancy. On the one hand, it needs to be avoided in order to achieve an extended shelf life in food products like sauces, creams and several milk products. On the other hand, during the manufacturing of products like ice cream, butter and whipped toppings partial coalescence is required to achieve the desired product properties. It contributes to the structure formation, the physicochemical properties (stability, firmness,...) and the sensory perception, like fattiness and creaminess of the final food products. This review critically summarises the findings of partial coalescence in oil-in-water emulsions in order to provide insight in how to enhance and retard it. Next to the pioneering work, a large set of experimental results of more recent work is discussed. First, the general mechanism of partial coalescence is considered and a distinction is made between partial and 'true' coalescence. The main differences are: the required solid particles in the dispersed oil phase, the formation of irregular clusters and the increased aggregation rate. Second, the kinetics of partial coalescence is discussed. In more detail, potential parameters affecting the rate of partial coalescence are considered by means of the encounter frequency and capture efficiency of the fat globules. The flow conditions, the fat volume fraction and the physicochemical properties of continuous aqueous phase affect both the encounter frequency and capture efficiency while the actual temperature, temperature history and the composition and formulation of the emulsion mainly affect the capture efficiency.

Ultrasonic assessment of the melting behaviour in fat from Iberian dry-cured hams

The feasibility of using ultrasounds to characterize the melting properties of fat from Iberian dry-cured hams was evaluated. Differential Scanning Calorimetry (DSC) and ultrasonic measurements were used to characterize the fat melting. The ultrasonic velocity in fat decreased with the increase in temperature, showing four different sections (0-4 degrees C, 4-10 degrees C, 10-20 degrees C and 20-24 degrees C). Ultrasonic velocity was related (R(2)=0.99) to the percentage of melted fat (%MEF) showing an increase of 5.4 ms(-1) for 1% increase of melted fat (%MEF above 60%). The thermal history did not affect the ultrasonic measurements from 10 to 25 degrees C and, consequently, this range was the most suitable for classifying Iberian dry-cured products with different genetics and feeding backgrounds. Ultrasonic measurements could be a reliable technique to estimate the %MEF and subsequently the related sensory attributes in Iberian dry-cured ham at 10-25 degrees C, which is the common temperature range for the consumption of Iberian dry-cured products.

Temperature scanning ultrasonic velocity study of complex thermal transformations in solid lipid nanoparticles

The purpose of this study was to determine whether temperature scanning ultrasonic velocity measurements could be used to monitor the complex thermal transitions that occur during the crystallization and melting of triglyceride solid lipid nanoparticles (SLNs). Ultrasonic velocity ( u) measurements were compared with differential scanning calorimetry (DSC) measurements on tripalmitin emulsions that were cooled (from 75 to 5 degrees C) and then heated (from 5 to 75 degrees C) at 0.3 degrees C min (-1). There was an excellent correspondence between the thermal transitions observed in deltaDelta u/delta T versus temperature curves determined by ultrasound and heat flow versus temperature curves determined by DSC. In particular, both techniques were sensitive to the complex melting behavior of the solidified tripalmitin, which was attributed to the dependence of the melting point of the SLNs on particle size. These studies suggest that temperature scanning ultrasonic velocity measurements may prove to be a useful alternative to conventional DSC techniques for monitoring phase transitions in colloidal systems.