Food is a complex soft matter, because various components, such as proteins, lipids, and carbohydrates, are self-assembled via non-covalent, colloidal interactions and form hierarchical structures at ...multiple length scales. Soft matter scientists have shown an increasing interest in understanding the general principles governing the food structure formation. During the last several decades, an increasing number of studies have shown that the maintenance of healthy gastrointestinal tract and its microbiome is essential for human health and wellbeing. The realization of the importance of the gastrointestinal microbiome has led to the development of
probiotics
, which are defined as living bacteria that confer a health benefit on the host. Probiotic bacteria and enzymes can be delivered to the intestinal system by formulating appropriate carriers and including these into food ingested by humans. Despite this simple statement, it involves many challenges in the field of soft matter science. This review aims to highlight how the key concepts in soft matter science can be used to design, characterize, and evaluate self-assembled formulations of probiotics and enzymes based on lipids and biopolymers. The topics covered in this review includes the emulsification of oil-water mixtures, the self-assembly of lipids and polymers at interfaces, the electrostatics and viscoelasticity of interfaces, and the wetting/adhesion of colloidal particles.
The aim of the current study was to elucidate whether cows and young bulls require different combinations of heating temperature and heating time to reduce toughness of the meat. The combined effect ...of heating temperature and time on toughness of semitendinosus muscle from the two categories of beef was investigated and the relationship to properties of connective tissue was examined. Measurements of toughness, collagen solubility, cathepsin activity and protein denaturation of beef semitendinosus heated at temperatures between 53°C and 63°C for up to 19 1/2h were conducted. The results revealed that slightly higher temperatures and prolonged heating times were required to reduce toughness of semitendinosus from cows to the same level as in young bulls. Reduced toughness of semitendinosus as a result of low temperature for prolonged time is suggested to result from weakening of the connective tissue, caused partly by denaturation or conformational changes of the proteins and/or by solubilization of collagen.
► Toughness of semitendinosus from cows and young bulls was reduced by LTLT treatment. ► At 63°C semitendinosus from cows and young bulls were equally tender. ► Weakening of connective tissue is suggested to be involved in toughness reduction. ► Cathepsins B and L were active during the heat treatment.
Differential scanning calorimetry (DSC) is a method widely used to examine the melting or crystallization profile of cocoa butter and chocolate. The (perceived) ease of use makes the method very ...appealing not only in academia, but also in the chocolate industry. Our study presents a critical evaluation of the parameters that influence the generated information (i.e., the apparent melting point and specific heat of fusion) on dark chocolates of various cocoa contents and evaluates the suitability of DSC as generic or “universal” analytical method. The tested parameters included sample weight and form, temperature protocol, and heating rate. In general, the melting point of all dark chocolates increased as a function of increasing heating rate. The weight and form of the samples influenced the melting points but not the specific heat of fusion, while the starting temperatures of the thermal analysis did not seem to affect the melting profiles of the chocolates. We observe that a comparison between different studies researching chocolate behavior using DSC is not trivial due to insufficient detail on the procedure followed and conclude that DSC is maybe better suited for inner-study comparisons.
The effect of selected monoglycerides on droplet morphology and rheology of palm kernel oil emulsions was studied. Combination of lactic acid ester of monoglycerides (LACTEM) and unsaturated ...monoglycerides (GMU) yielded highly viscous emulsions caused by partial coalescence. LACTEM combined with saturated monoglycerides (GMS) or diacetyl tartaric acid ester of monoglycerides (DATEM) gave low-viscous emulsions. The rheological behavior was found not to be related to polymorphic transformations of fat in the emulsions.
A possible relationship between structural changes of emulsions and the effect of monoglyceride crystallization behavior of PKO was examined by studying the monoglycerides' influence on crystallization of bulk PKO. Polymorphic transformation, crystallization kinetics and melting/crystallization profile of bulk PKO were analyzed. The monoglycerides had minor effect on crystallization behavior of bulk PKO compared to the major impact on emulsion stability. This indicates that emulsifiers act differently in bulk and dispersed fat. For PKO the structural changes of the emulsions were independent of the effects of monoglycerides on the crystallization of bulk fat.
•GMU, GMS, DATEM and LACTEM strongly affect the rheological properties of emulsions.•LACTEM based PKO emulsions ranged from highly to low viscous.•Aggregation of emulsions were independent of fat polymorphic transformations.
Myofibers and collagen show non-linear optical properties enabling imaging using second harmonic generation (SHG) microscopy. The technique is evaluated for use as a tool for real-time studies of ...thermally induced changes in thin samples of unfixed and unstained pork. The forward and the backward scattered SHG light reveal complementary features of the structures of myofibers and collagen fibers. Upon heating the myofibers show no structural changes before reaching a temperature of 53 °C. At this temperature the SHG signal becomes extinct. The extinction of the SHG at 53 °C coincides with a low-temperature endotherm peak observable in the differential scanning calorimetry (DSC) thermograms. DSC analysis of epimysium, the connective tissue layer that enfold skeletal muscles, produces one large endotherm starting at 57 °C and peaking at 59.5 °C. SHG microscopy of collagen fibers reveals a variability of thermal stability. Some fibers show severe shrinkage at 57 °C, before the signal for most of them vanishes between 59 °C and 61 °C and thus coinciding with the endotherm of the thermograms. However, in some areas, strong SHG signals from collagen can be visualized even after prolonged heating to 67 °C and thus indicating regions of much higher thermal stability. It is seen that the benefits of the structural and temporal information available from SHG microscopy reveals complementary information to a traditional DSC measurement and enables a more complete understanding of the thermal denaturation process.
The aim of this research was to introduce a novel method to use zein protein and stabilize an ethanol-based emulsion. To study the effect of ethanol in the continuous phase of the emulsion on the ...stability and microstructure of the emulsions, ethanol content was tuned in the range of 50–90 %v/v. Also, the effect of zein concentration on the stability of ethanol-based emulsions was examined. The microstructure and mean droplet size of emulsions were measured using static light scattering (SLS), with Coherent Anti-Stokes Raman Scattering (CARS) Microscopy combined with image processing. The results showed that the effect of ethanol concentration on the interfacial tension and zein solubility plays a substantial role in the formation, stability, and microstructure of emulsions. The data indicated that 70 %v/v ethanol content resulted in the lowest interfacial tension between oil and ethanol-water mixture in the presence of 10 %w/v zein. Therefore, the minimum mean droplet size was achieved at 70 %v/v ethanol equal to around 10 μm. Furthermore, increasing zein concentration decreased oil droplet mean size and enhanced the emulsion stability against Ostwald ripening.
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•Zein protein can stabilize oil in aqueous ethanol emulsion.•Ethanol quantity can affect the stability of zein-stabilized emulsion drastically.•The surface activity of zein was an interplay between zein solubility and effect of ethanol on interfacial tension.
For a food product to be a success in the marketplace it must be stable throughout its shelf-life. Quality deterioration due to chemical changes and alterations in condition due to physical ...instability are not always recognized, yet can be just as problematic as microbial spoilage. This book provides an authoritative review of key topics in this area. Chapters in Part I focus on the chemical reactions which can negatively affect food quality, such as oxidative rancidity, and their measurement. Part I reviews quality deterioration associated with physical changes, such as moisture loss, gain and migration, crystallization and emulsion breakdown. This book outlines the likely effects on different foods and beverages, including bakery products, fruit and vegetables, ready-to-eat meals and wine.
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