Based on the type of vegetable, the different processes applied led to microstructures with different rheological properties. This study shows that particle size distribution, morphology and phase volume are important parameters to explain the complex relationship between rheology and microstructure for these types of systems.

High-pressure homogenization, as a way to further mechanically disrupt plant cells and cell walls compared to conventional blending, has been applied to thermally treated and comminuted carrot and tomato material in the presence of 5% olive oil. Mixes of both vegetables in a 1:1 ratio were also included. Both the effect of homogenization pressure and the effect of multiple process cycles were studied. The different microstructures generated were linked to different rheological properties analyzed by oscillatory and steady state measurements. The results showed that while carrot tissue requires a high shear input to be disrupted into cells and cell fragments, tomato cells were broken across the cell walls already at moderate shear input, and the nature of the tomato particles changed to amorphous aggregates, probably composed of cell contents and cell wall polymers. All the plant stabilized emulsions generated were stable against creaming under centrifugation. While for tomato a low-pressure multiple cycle and a high-pressure single-cycle process led to comparable microstructures and rheological properties, carrot showed different rheological properties after these treatments linked to differences in particle morphology. Mixes of carrot and tomato showed similar rheological properties after homogenizing in a single or in a split-stream process. Practical Application: Following consumers' demand, the food industry has shown a growing interest in manufacturing products free of gums and stabilizers, which are often perceived as artificial. By tailored processing, fresh plant material could be used to structure food products in a more natural way while increasing their nutritional quality.

The effects of conventional industrial processing steps on global phytochemical composition of broccoli, tomato and carrot purees were investigated by using a range of complementary targeted and untargeted metabolomics approaches including LC-PDA for vitamins, (1)H NMR for polar metabolites, accurate mass LC-QTOF MS for semi-polar metabolites, LC-MRM for oxylipins, and headspace GC-MS for volatile compounds. An initial exploratory experiment indicated that the order of blending and thermal treatments had the highest impact on the phytochemicals in the purees. This blending-heating order effect was investigated in more depth by performing alternate blending-heating sequences in triplicate on the same batches of broccoli, tomato and carrot. For each vegetable and particularly in broccoli, a large proportion of the metabolites detected in the purees was significantly influenced by the blending-heating order, amongst which were potential health-related phytochemicals and flavour compounds like vitamins C and E, carotenoids, flavonoids, glucosinolates and oxylipins. Our metabolomics data indicates that during processing the activity of a series of endogenous plant enzymes, such as lipoxygenases, peroxidases and glycosidases, including myrosinase in broccoli, is key to the final metabolite composition and related quality of the purees.

In this study, the impact of mechanical treatments on the physicochemical and emulsifying properties of hen egg yolk and its fractions plasma and granules has been assessed. Yolk, plasma, and granule dispersions at pH 4.0 and 0.75 M NaCl were subjected to rotor-stator and high-pressure pretreatments at different dynamic pressure levels: 30, 100, and 200 bar at 20 degrees C. Physicochemical characteristics (protein solubility, rheological behavior, and micro- and ultra-structures) and emulsifying properties (oil/water 60:40 emulsions: droplet size and flocculation, protein adsorption) of control dispersions and dispersions subjected to mechanical pretreatments (rotor-stator or high pressure) were compared. Homogenization at high pressures (100 and 200 bar) led to a decreased protein solubility and to an increase in apparent viscosity of yolk and plasma dispersions. These pressures certainly disrupted low-density lipoproteins (LDL) particles and generated aggregates of proteins liberated from LDL and livetins in the plasma fraction, and led to a moderated reorganization of the microstructure of granules. Despite the modifications observed in the pretreated plasma and granules dispersions, the oil droplet diameter and the bridging flocculation obtained in emulsions made with these dispersions were similar to that obtained with untreated dispersions. Results concerning interfacial protein adsorption suggested that preformed or natural aggregates at least partially persist at the oil-water interface.