900 research outputs found
Lipid oxidation in emulsified food products
No full textMost lipids in food exist as colloidal dispersions stabilized by surface active agents that slow down the gravitational separation of oil and water. The surface active agents in emulsion create an oil-water interface that has major impacts on the distribution of the components in foods that impact lipid oxidation. This includes location and reactivity of prooxidative factors such as transition metals, lipid hydroperoxides and minor lipid components and antioxidants such as free radical scavengers and metal chelators. Understanding of how the physical properties of the lipid-oil interface in food emulsions impacts the chemistry of lipid oxidation has lead to new strategies to inhibit oxidation such as creating charged surfaces that electrostatically repel metals and thick interfaces that inhibit lipid-prooxidant interactions. As food formulations continue to move towards inclusion of more polyunsaturated fatty acids and the use of traditional antioxidants becomes more limited due to increased consumer demand for all natural foods, it is important to have a better understanding of the mechanisms of lipid oxidation in foods dispersion so that novel antioxidant technologies can be developped
Bridging the gap: use of confocal microscopy in food research
No full textLaser scanning confocal microscopy (LSCM), one of the most powerful techniques in multidimensional and chemical microscopy, has the potential applications in food research. The method not only provides an image with better resolution than conventional light microscopy or fluorescence microscopy, but also provides an opportunity to observe a 3-D image without the need to physically section and observe the sample in the z-direction. Additionally, it can distinguish the spatial location of different components by detecting fluorescence from dyes specific to different chemical species
The use of ultrasonics for characterising fats and emulsions
No full textUltrasonics has not found widespread use in the food industry, despite having considerable potential for characterising food materials. This is due to the complexity and diversity of food materials, the lack of suitable instrumentation and a poor understanding of how
ultrasound interacts with many food components. In this work it is shown how a good appreciation of the theories describing ultrasonic propagation in heterogeneous materials, coupled with careful experimental design, leads to many new applications of ultrasonics for characterising fats and emulsions. Ultrasonic measurements were made using either a pulse echo technique (1-10MHz), or a pulse echo interferometric technique (5-55MHz).
The ultrasonic velocities of a series of 0-30% w/w glyceride/oil mixtures and some commercial fats were measured with varying temperature (0-70°C) at 1MHz. Ultrasonic scattering was not important in these systems and so empirical equations or simple (SFC) theoretical formulae could be used to relate the measured velocities to the solid fat contents (SFC) of the samples. There were very significant correlations between the SFCs determined using ultrasonics and those determined using pulsed NMR (r > 0.99), and so ultrasonics should prove a useful adjunct or alternative to NMR. Velocity measurements also proved useful for characterising vegetable oils since the velocity of an oil could be related to its glyceride composition.
The ultrasonic velocity and attenuation of a series of sunflower oil and water emulsions mean were measured with varying frequency (1-55MHz) mean, droplet size (0.1-0.9μm), disperse phase mass fraction (0-0.5) and emulsion type (0/W and W/O). Scattering was significant in these emulsions and could be used to measure their disperse phase mass fractions and particle size distributions. Ultrasonics has important advantages over existing techniques for this type of measurement since it can be used in emulsions which are optically opaque, in a non-intrusive, non-invasive manner
Spray drying, freeze drying and related processes for food ingredient and nutraceutical encapsulation
No full textWide varieties of techniques are currently available for encapsulation of active components in food and nutraceutical industries. Spray drying and freeze drying technologies have been commonly applied due to their outstanding advantages in availability of the equipment facility, high product stability, low product volume and weight, reduced storage space and transportation cost, and ease of handling and reconstitution of encapsulated powders. This chapter describes the principles and processing techniques of spray drying and freeze drying for encapsulation of food ingredients and nutraceuticals. Some specific applications are also described for encapsulation of different types of core materials. The limits and challenges of these techniques in relation to research and commercial applications are also briefly introduced
Wave propagation, phase mixing and dissipation in Hall MHD
No full textIn this thesis the effect of the Hall term in the generalised Ohm’s law on Alfvén (shear) and fast wave propagation and dissipation in the ion cyclotron frequency range is investigated.
The damping of an initially Gaussian field perturbation in a uniform Hall MHD plasma is treated analytically. Subsequently a 2D Lagrangian remap code (Lare2d) is used to study the damping and phase mixing of initially Gaussian field perturbations and a harmonic series of boundary-driven perturbations in a uniform field (in the presence of a transverse equilibrium density gradient). The same code is then used to study a range of initially shear and fast-wave perturbations in the vicinity of a magnetic X-type null point.
The magnetic energy associated with an initially Gaussian field perturbation in a uniform resistive plasma is shown to decay algebraically at a rate that is unaffected by the Hall term to leading order in kδ where k is wavenumber and δ is ion skin depth. A similar decay law applies to whistler perturbations in the limit kδ>>>1.
We demonstrate that in both geometries considered, the inclusion of the Hall term reduces the effectiveness of phase-mixing in plasma heating. The reduction in the damping rate in the uniform field (non-uniform density) cases, arising from dispersive effects, tends to zero in both the weak and strong phase mixing limits. In the Hall MHD X-point case, minimal reductions are seen for initially shear wave pulses, suggesting that little or no phase-mixing takes place. Nonlinear fast wave pulses which interact with the initial X-point destabilise the local field sufficiently to generate multiple null pairs; subsequent oscillatory current sheet behaviour appears unaffected by earlier differences between the MHD and Hall MHD cases
IMPACTS OF HOUSEHOLD COMPOSITION ON CONVENIENCE AND NONCONVENIENCE FOOD EXPENDITURES IN THE SOUTH
No full textConsumer/Household Economics,
Properties and applications of different probiotic delivery systems
No full textProbiotic products should contain and maintain viable cells during the product shelf life at least above therapeutic minimum level for the benefit of consumers. Due to their generally poor viability and stability in food products, especially in fermented dairy products, as well as in the host gastrointestinal tract, various microencapsulation techniques for probiotics have been developed in recent years to overcome these issues. This chapter describes the benefit of microencapsulation, various encapsulation techniques used to encapsulate probiotics and the application of encapsulated probiotics in selected food systems. The use of various supporting or encapsulating materials, such as alginate, chitosan and carrageenan is also discussed. Special treatments (such as complexation coating) of capsules for further improving the stability of the probiotics are also described
Celebrating the centenary in polymer science: drawing inspiration from nature to develop anti-fouling coatings. The development of biomimetic polymer surfaces and their effect on bacterial fouling.
No full textInvited paperJake McClements, Luciana C. Gomes, Joshua Spall, Fabien Saubade,Devine Akhidime, Marloes Peeters, Filipe J. Mergulh\ue3o and Kathryn A. Whitehead*Celebrating the centenary in polymerscience: drawing inspiration from nature todevelop anti-fouling coatings. Thedevelopment of biomimetic polymer surfacesand their effect on bacterial foulinghttps://doi.org/10.1515/pac-2021-0108Abstract:The development of self-cleaning biomimetic surfaces has the potential to be of great benefit tohuman health, in addition to reducing the economic burden on industries worldwide. Consequently, thisstudy developed a biomimetic wax surface using a moulding technique which emulated the topography ofthe self-cleaningGladiolus hybridus(Gladioli) leaf. A comparison of topographies was performed for un-modified wax surfaces (control), biomimetic wax surfaces, and Gladioli leaves using optical profilometryand scanning electron microscopy. The results demonstrated that the biomimetic wax surface and Gladiolileaf had extremely similar surface roughness parameters, but the water contact angle of the Gladioli leaf wassignificantly higher than the replicated biomimetic surface. The self-cleaning properties of the biomimeticand control surfaces were compared by measuring their propensity to repelEscherichia coliandListeriamonocytogenesattachment, adhesion, and retention in mono- and co-culture conditions. When the bacterialassays were carried out in monoculture, the biomimetic surfaces retained fewer bacteria than the controlsurfaces. However, when using co-cultures of the bacterial species, only following the retention assays werethe bacterial numbers reduced on the biomimetic surfaces. The results demonstrate that such surfaces maybe effective in reducing biofouling if used in the appropriate medical, marine, and industrial scenarios. Thisstudy provides valuable insight into the antifouling physical and chemical control mechanisms found inplants, which are particularly appealing for engineering purposes
Fusion product studies via fast ion D-D and D-3He fusion on JET
No full textDedicated fast ion D-D and D-3He fusion experiments were performed on JET with carbon wall (2008) and ITER-like wall (2014) for testing the upgraded neutron and energetic ion diagnostics of fusion products. Energy spectrum of D-D neutrons was the focus of the studies in pure deuterium plasmas. A significant broadening of the energy spectrum of neutrons born in D-D fast fusion was observed, and dependence of the maximum D and D-D neutron energies on plasma density was established. Diagnostics of charged products of aneutronic D-3He fusion reactions, 3.7 MeV alpha-particles similar to those in D-T fusion, and 14.6 MeV protons, were the focus of the studies in D-3He plasmas. Measurements of 16.4 MeV gamma-rays born in the weak secondary branch of D(3He, γ)5Li reaction were used for assessing D-3He fusion power. For achieving high yield of D-D and D-3He reactions at relatively low levels of input heating power, an acceleration of D beam up to the MeV energy range was used employing 3rd harmonic () ICRH technique. These results were compared to the techniques of D beam injection into D-3He mixture, and 3He-minority ICRH in D plasmas
Cream replacement by hydrocolloid-stabilized emulsions to reduce fat digestion in panna cottas
No full text[EN] The effect of emulsions based on different hydrocolloids (xanthan gum, hydroxypropyl methylcellulose and methylcellulose) on the structural, textural and sensory properties and lipid digestibility of panna cottas was investigated. The hydrocolloid-based emulsions presented similar microstructures. However, the panna cottas formulated with these emulsions presented large microstructural differences, which therefore also led to different textural and sensory properties. The differences in the initial microstructure of the panna cottas, the microstructural changes that they exhibited at the beginning of lipid digestion and the mechanisms of emulsification imparted by the hydrocolloids led to different extents of digestion. The panna cotta prepared with the hydroxypropyl methylcellulose-based emulsion was well accepted by the consumers and presented lower initial rate and extent of digestion (rate: 1,52% free fatty acid (FFA)/min; extent: 49.72% FFA) than the control panna cotta (3.69% FFA/min; 61.81% FFA). These results may contribute to the manufacture of reduced lipid digestion foods which could be used in weight management.The authors are grateful to the Spanish Ministry of the Economy and Competitiveness for financial support (AGL2015-68923-C2-2-R (MINECO/FEDER)) and gratefully acknowledge the financial support of EU FEDER funds. They would also like to thank Mary Georgina Hardinge for assistance in correcting the English manuscript. There are no conflicts of interest to declare.Borreani, J.; Hernando Hernando, MI.; Quiles Chuliá, MD. (2020). Cream replacement by hydrocolloid-stabilized emulsions to reduce fat digestion in panna cottas. LWT - Food Science and Technology. 119:1-7. https://doi.org/10.1016/j.lwt.2019.108896S17119Arancibia, C., Castro, C., Jublot, L., Costell, E., & Bayarri, S. (2015). Colour, rheology, flavour release and sensory perception of dairy desserts. Influence of thickener and fat content. LWT - Food Science and Technology, 62(1), 408-416. doi:10.1016/j.lwt.2014.08.024Bellesi, F. A., Martinez, M. J., Pizones Ruiz-Henestrosa, V. M., & Pilosof, A. M. R. (2016). Comparative behavior of protein or polysaccharide stabilized emulsion under in vitro gastrointestinal conditions. Food Hydrocolloids, 52, 47-56. doi:10.1016/j.foodhyd.2015.06.007Borreani, J., Espert, M., Salvador, A., Sanz, T., Quiles, A., & Hernando, I. (2017). Oil-in-water emulsions stabilised by cellulose ethers: stability, structure and in vitro digestion. Food & Function, 8(4), 1547-1557. doi:10.1039/c7fo00159bBorreani, J., Hernando, I., Salvador, A., & Quiles, A. (2017). New hydrocolloid-based emulsions for replacing fat in panna cottas: a structural and sensory study. Journal of the Science of Food and Agriculture, 97(14), 4961-4968. doi:10.1002/jsfa.8373Borreani, J., Llorca, E., Quiles, A., & Hernando, I. (2017). Designing dairy desserts for weight management: Structure, physical properties and in vitro gastric digestion. Food Chemistry, 220, 137-144. doi:10.1016/j.foodchem.2016.09.202Espert, M., Borreani, J., Hernando, I., Quiles, A., Salvador, A., & Sanz, T. (2017). Relationship between cellulose chemical substitution, structure and fat digestion in o/w emulsions. Food Hydrocolloids, 69, 76-85. doi:10.1016/j.foodhyd.2017.01.030Espinal-Ruiz, M., Parada-Alfonso, F., Restrepo-Sánchez, L.-P., Narváez-Cuenca, C.-E., & McClements, D. J. (2014). Impact of dietary fibers [methyl cellulose, chitosan, and pectin] on digestion of lipids under simulated gastrointestinal conditions. Food Funct., 5(12), 3083-3095. doi:10.1039/c4fo00615aHe, Q., Hort, J., & Wolf, B. (2016). Predicting sensory perceptions of thickened solutions based on rheological analysis. Food Hydrocolloids, 61, 221-232. doi:10.1016/j.foodhyd.2016.05.010Hernández-Carrión, M., Vázquez-Gutiérrez, J. L., Hernando, I., & Quiles, A. (2013). Impact of High Hydrostatic Pressure and Pasteurization on the Structure and the Extractability of Bioactive Compounds of Persimmon «Rojo Brillante». Journal of Food Science, 79(1), C32-C38. doi:10.1111/1750-3841.12321Katzbauer, B. (1998). Properties and applications of xanthan gum. Polymer Degradation and Stability, 59(1-3), 81-84. doi:10.1016/s0141-3910(97)00180-8Lett, A. M., Norton, J. E., & Yeomans, M. R. (2016). Emulsion oil droplet size significantly affects satiety: A pre-ingestive approach. Appetite, 96, 18-24. doi:10.1016/j.appet.2015.08.043Lett, A. M., Yeomans, M. R., Norton, I. T., & Norton, J. E. (2016). Enhancing expected food intake behaviour, hedonics and sensory characteristics of oil-in-water emulsion systems through microstructural properties, oil droplet size and flavour. Food Quality and Preference, 47, 148-155. doi:10.1016/j.foodqual.2015.03.011Li, Y., Hu, M., & McClements, D. J. (2011). Factors affecting lipase digestibility of emulsified lipids using an in vitro digestion model: Proposal for a standardised pH-stat method. Food Chemistry, 126(2), 498-505. doi:10.1016/j.foodchem.2010.11.027Li, Y., & McClements, D. J. (2010). New Mathematical Model for Interpreting pH-Stat Digestion Profiles: Impact of Lipid Droplet Characteristics on in Vitro Digestibility. Journal of Agricultural and Food Chemistry, 58(13), 8085-8092. doi:10.1021/jf101325mLobato-Calleros, C., Reyes-Hernández, J., Beristain, C. I., Hornelas-Uribe, Y., Sánchez-García, J. E., & Vernon-Carter, E. J. (2007). Microstructure and texture of white fresh cheese made with canola oil and whey protein concentrate in partial or total replacement of milk fat. Food Research International, 40(4), 529-537. doi:10.1016/j.foodres.2006.10.011McClements, D. J., Decker, E. A., Park, Y., & Weiss, J. (2008). Designing Food Structure to Control Stability, Digestion, Release and Absorption of Lipophilic Food Components. Food Biophysics, 3(2), 219-228. doi:10.1007/s11483-008-9070-yMun, S., Decker, E. A., & McClements, D. J. (2007). Influence of emulsifier type on in vitro digestibility of lipid droplets by pancreatic lipase. Food Research International, 40(6), 770-781. doi:10.1016/j.foodres.2007.01.007Mun, S., Kim, J., McClements, D. J., Kim, Y.-R., & Choi, Y. (2017). Fluorescence imaging of spatial location of lipids and proteins during digestion of protein-stabilized oil-in-water emulsions: A simulated gastrointestinal tract study. Food Chemistry, 219, 297-303. doi:10.1016/j.foodchem.2016.09.158Qin, D., Yang, X., Gao, S., Yao, J., & McClements, D. J. (2016). Influence of Hydrocolloids (Dietary Fibers) on Lipid Digestion of Protein-Stabilized Emulsions: Comparison of Neutral, Anionic, and Cationic Polysaccharides. Journal of Food Science, 81(7), C1636-C1645. doi:10.1111/1750-3841.13361Qiu, C., Zhao, M., Decker, E. A., & McClements, D. J. (2015). Influence of anionic dietary fibers (xanthan gum and pectin) on oxidative stability and lipid digestibility of wheat protein-stabilized fish oil-in-water emulsion. Food Research International, 74, 131-139. doi:10.1016/j.foodres.2015.04.022Sanz, T., Falomir, M., & Salvador, A. (2015). Reversible thermal behaviour of vegetable oil cellulose ether emulsions as fat replacers. Influence of glycerol. Food Hydrocolloids, 46, 19-27. doi:10.1016/j.foodhyd.2014.11.030Torcello-Gómez, A., & Foster, T. J. (2016). Influence of interfacial and bulk properties of cellulose ethers on lipolysis of oil-in-water emulsions. Carbohydrate Polymers, 144, 495-503. doi:10.1016/j.carbpol.2016.03.00
- …
