The structured food systems (i.e. cellular tissues) are dissipative structures whose functionality mainly concerns their properties (physico-chemical properties, chemical and biochemical reactions), external interactions with surroundings (interactions with micro-organisms, heat and mass transport pathway) and especially, their interactions with consumers (nutritional value, quality, taste and flavour, texture, appearance: size, shape, colour). Dehydration or rehydration processes concern heat and mass transport phenomena (water, solutes) coupled with micro and macrostructure changes both producing important effects on food functionality. Control of these changes is the major concern in food product development. This control must be applied not only to the changes in physico-chemical properties but also to those related with consumers' issues. Food matrixengineering is a branch of food engineering which aims to apply the knowledge of the food matrixcomposition, structure and properties to promote and control adequate changes which can improve some sensorial and/or functional properties in the food. These changes, which are caused by some basic operations, are related to the phenomena of heat and mass transfer, vaporization-condensation, internal gas or liquid release, structure deformation-relaxation and phase transitions in matrixcomponents, and are usually coupled throughout the operation's progress. The final product may be a new product with improved composition and sensorial properties and/or more stability. All these concepts are discussed in this paper using several examples related to the application of combined food dehydration techniques.

Water is a major component of drinking water, beverages, and most foodstuffs. In this study, an effort has been made to employ selected properties of water for: (1) evaluation of interactions of water with other food components; (2) discussion on the effects of water properties on food and beverage products; (3) applications of water properties in food technology; and (4) comparison of water properties with corresponding properties of similar substances. This study provides the following major conclusions: (i) unusual properties of water are mostly due to its high permanent dipole moment, partial ionic character of O–H covalent bonds, and extensive hydrogen bonds; (ii) different properties of many foodstuffs are strongly related to various properties of water; (iii) the properties of food products change depending on water availability and temperature; (iv) preparation of drinking water is a prerequisite for production of any safe drinks and foodstuffs; (v) water contributes important roles in quality, flavor, and shelf-life of foods; and (vi) water is used in food industries as a fluid for heat transfer; as a medium for temperature moderation in food processing; as a solvent for sugars, salts, water-soluble vitamins, and acids; as a dispersing agent for hydrophilic food components; as a dispersed phase for emulsified products; or as a reactant for several reactions in food processing.

In the present investigation, emulsifying potential of galactan exopolysaccharide (EPS) extracted from Weissella confusa KR780676 has been evaluated with various food grade flavours (vanilla, cardamom and pineapple). Concentration of EPS was optimized as 1% with these flavours, in addition to the effect of salinity (NaCl), monovalent ion (KCl) and temperature on emulsion activity (EA), and emulsion stability (ES) was also inspected. Filter paper wetting test exhibited water-in-oil-in-water (w/o/w) and oil-in-water (o/w) type emulsions. The extent in granule disintegration and the retrogradation process of flavour emulsions were studied with pasting properties. Electron micrography and particle size analysis revealed the morphology and the size of emulsion droplets. Thermal stability of emulsions has found 100% at various temperatures (−20 to 60 °C) for vanilla and pineapple flavour, whereas, it was varying for cardamom as per the temperature disparity. Emulsion stability of vanilla and pineapple flavour was retained as such for various concentrations of NaCl whereas decreased for cardamom in direct proportion. In case of KCl all the three flavours showed greater stability. These emulsifying properties indicate that galactan EPS can be a prospective alternative to commercial biopolymers in food and pharmaceuticals industries.

The thermal reaction between cysteine and furfural was investigated at 65 degrees C in five-component food grade oil/water (O/W) microemulsions of R-(+)-limonene/ethanol, EtOH/water/propylene glycol, PG/Tween 60 as apart of a systematic study on the generation of aroma compounds by utilizing structured W/O and O/W fluids. The furfural-cysteine reaction led to the formation of unique aroma compounds such as 2-furfurylthiol (FFT), 2-(2-furanyl)thiazolidine (main reaction product), 2-(2-furanyl)-thiazoline, and N-(2-mercaptovinyl)-2-(2-furanyl)thiazolidine. These products were determined and characterized by GC-MS. Enhancement in flavor formation is termed "microemulsion catalysis". The chemical reaction occurs preferably at the interfacial film, and therefore a pseudophase model was assumed to explain the enhanced flavor formation. The product internal composition is dictated by process conditions such as temperature, time, pH, and mainly the nature of the interface. Increasing water/PG ratio leads to a dramatic increase in the initial reaction rate (V0). V0 increased linearly as a function of the aqueous phase content, which could be due to the increase in the interfacial concentration of furfural. Microemulsions offer a new reaction medium to produce selective aroma compounds and to optimize their formation.

Engineering the interface of oil-in-water emulsion droplets with biopolymers that modify its permeability could provide a novel technique to improve flavour retention in dry powders. The objective of this study was to determine if volatile compounds were more retained in dry emulsions stabilized by pea protein isolate (PPI)/pectin complex than that stabilized by PPI alone. The retention of ethyl esters during spray-drying increased with decreasing volatility of the encapsulated compound and ranged from 28% to 40%. The addition of pectin to feed emulsions was quite effective in markedly improving the retention of the three studied flavour compounds. In our previous work (Gharsallaoui et al., 2010), we showed that pectin was able to improve physical integrity of emulsion oil droplets during spray-drying. However, the pectin positive effect on both the droplet stability and the flavour retention at the time of spray-drying can also be explained by a protein molecular structure protective effect. Indeed, the obtained FTIR results showed that pectin was able to preserve the β-sheet secondary structure of pea protein when pea globulins/pectin complexes are heated. The study of the release characteristics of a flavour compound from dried powders showed that pectin addition did not affect the release profile mainly accomplished by the diffusion mechanism.

The aim of this study was to compare the efficiency of three different food‐grade emulsifiers to form and stabilise an orange oil‐in‐water emulsion. The emulsifier type and concentration had a profound effect on the initial particle size of the oil droplets with Tween 80 being the most effective in reducing the particle size (1% w/w, 1.88 ± 0.01 μm) followed by sodium caseinate (10% w/w, 2.14 ± 0.03 μm) and gum arabic (10% w/w, 4.10 ± 0.24 μm). The long‐term stability of the concentrated beverages was monitored using Turbiscan analysis. The Turbiscan stability indices after 4 weeks of storage followed the order: Tween 80 (1.70 ± 0.08) < gum arabic (4.83 ± 0.53) < sodium caseinate (6.20 ± 1.56). The protein emulsifier was more capable to control the oxidation process, and this was attributed to the excess amount of emulsifier present in the aqueous phase. This study provides useful insights into the formulation of flavour emulsions by the beverage industry.