Facile lipase-catalyzed synthesis of a chocolate fat mimetic

Carnauba wax and adipic acid oleogels as an innovative strategy for cocoa butter alternatives in chocolate spreads

The aim of this study was to replace cocoa butter substitute (CBS) with structured sunflower oil in chocolate spread partially. Two types of oleogel, 6% carnauba wax (CWO) and 2% carnauba wax with 4% adipic acid (AD-CWO) were substituted (at 20%, 50%, and 70%), and chocolate spread characteristics were evaluated. Various properties of chocolate spread samples were investigated as peroxide value, firmness, oil binding capacity, moisture content, molecular interactions, and molecular conformation of fat crystals. The increasement of CBS substitution by oleogel in samples significantly reduced firmness. The samples with 20% replacement formulated by CWO and AD-CWO had the highest oil binding capacity, 97.48 ± 0.21% and 97.73 ± 0.02, respectively. Moreover, oxidative stability analysis showed a positive correlation with an increasing replacement level over 90 days of storage. Based on FT-IR analysis, the new intermolecular hydrogen bond formation in the oleogel-based spreads network has been confirmed. CBS replacement with oleogels revealed the presence of stable β´ polymorphs with low intensity. In conclusion, the carnauba-based oleogels have significant potential to substitute CBS in chocolate spread partially.

The relationship between structure and rheology in a three-dimensional sheared lamellar mesophase

The evolution of a lamellar mesophase from an initially disordered state under shear is examined using simulations of a mesoscale model based on a concentration field ψ that distinguishes the hydrophilic and hydrophobic components. The Landau-Ginzburg free-energy functional is augmented by a term that is minimised for sinusoidal modulations in the concentration field with wavelength λ = (2π/k), and the dynamical equations are the model H equations. The structure and rheology are determined by the relative magnitudes of the diffusion time for coarsening, (λ²/D) and the inverse of the strain rate ^-1, and the Ericksen number, which is the ratio of the shear stress and the layer stiffness. When the diffusion time is small compared with the inverse of the strain rate, there is a local formation of misaligned layers, which are deformed by the imposed flow. There is near-perfect ordering with isolated defects at low values of the Ericksen number, but the defects result in a significant increase in viscosity due to the high layer stiffness. At high values of the Ericksen number, the concentration field is deformed by the mean shear before layers form via diffusion. Cylindrical structures aligned along the flow direction form after about 8-10 strain units, and these evolve into layers with disorder through diffusion perpendicular to the flow. The layers are not perfectly ordered, even after hundreds of strain units, due to the creation and destruction of defects via shear. The excess viscosity is low because the layer stiffness is small compared with the applied shear at a high Ericksen number. This study provides guidance on how the material parameters and imposed flow can be tailored to achieve the desired rheological behaviour.

Rational Design of Lipase ROL to Increase Its Thermostability for Production of Structured Tags

1,3-regiospecific lipases are important enzymes that are heavily utilized in the food industries to produce structured triacylglycerols (TAGs). The Rhizopus oryzae lipase (ROL) has recently gained interest because this enzyme possesses high selectivity and catalytic efficiency. However, its low thermostability limits its use towards reactions that work at lower temperature. Most importantly, the enzyme cannot be used for the production of 1,3-dioleoyl-2-palmitoylglycerol (OPO) and 1,3-stearoyl-2-oleoyl-glycerol (SOS) due to the high melting points of the substrates used for the reaction. Despite various engineering efforts used to improve the thermostability of ROL, the enzyme is unable to function at temperatures above 60 °C. Here, we describe the rational design of ROL to identify variants that can retain their activity at temperatures higher than 60 °C. After two rounds of mutagenesis and screening, we were able to identify a mutant ROL_10x that can retain most of its activity at 70 °C. We further demonstrated that this mutant is useful for the synthesis of SOS while minimal product formation was observed with ROL_WT. Our engineered enzyme provides a promising solution for the industrial synthesis of structured lipids at high temperature.

Evaluation of lipase access tunnels and analysis of substance transport in comparison with experimental data

Lipases (E.C. 3.1.1.3) have buried active sites and used access tunnels in the transport of substrates and products for biotransformation processes. Computational methods are used to predict the trajectory and energy profile of ligands through these tunnels, and they complement the experimental methodologies because they filter data, optimizing laboratory time and experimental costs. Access tunnels of Burkholderia cepacia lipase (BCL), Candida rugosa lipase (CRL), and porcine pancreas lipase (PPL) and the transport of fatty acids, alcohols and esters through the tunnels were evaluated using the online server CaverWeb V1.0, and server calculation results were compared with experimental data (productivity). BCL showed higher productivity with palmitic acid-C16:0 (4029.95 µmol/h mg); CRL obtained productivity for oleic acid-C18:1 (380.80 µmol/h mg), and PPL achieved productivity for lauric acid-C12:0 (71.27 µmol/h mg). The highest probability of transport for BCL is through the tunnels 1 and 2, for CRL through the tunnel 1, and for PPL through the tunnels 1, 2, 3 and 4. Thus, the best in silico result was the transport of the substrates palmitic acid and ethanol and product ethyl palmitate in tunnel 1 of BCL. This result corroborates with the best result for the productivity data (higher productivity for BCL with palmitic acid-4029.95 µmol/h mg). The combination of in silico evaluation and experimental data gave similar results, demonstrating that in silico approaches are a promising alternative for reducing screening tests and minimizing laboratory time in the bio-catalysis area by identifying the lipases with the greatest reaction potential, as in the case of this proposal.

Waste Management in the Agri-Food Industry: The Conversion of Eggshells, Spent Coffee Grounds, and Brown Onion Skins into Carriers for Lipase Immobilization

One of the major challenges in sustainable waste management in the agri-food industry following the “zero waste” model is the application of the circular economy strategy, including the development of innovative waste utilization techniques. The conversion of agri-food waste into carriers for the immobilization of enzymes is one such technique. Replacing chemical catalysts with immobilized enzymes (i.e., immobilized/heterogeneous biocatalysts) could help reduce the energy efficiency and environmental sustainability problems of existing chemically catalysed processes. On the other hand, the economics of the process strongly depend on the price of the immobilized enzyme. The conversion of agricultural and food wastes into low-cost enzyme carriers could lead to the development of immobilized enzymes with desirable operating characteristics and subsequently lower the price of immobilized enzymes for use in biocatalytic production. In this context, this review provides insight into the possibilities of reusing food industry wastes, namely, eggshells, coffee grounds, and brown onion skins, as carriers for lipase immobilization.

Thermostable lipases and their dynamics of improved enzymatic properties

Thermal stability is one of the most desirable characteristics in the search for novel lipases. The search for thermophilic microorganisms for synthesising functional enzyme biocatalysts with the ability to withstand high temperature, and capacity to maintain their native state in extreme conditions opens up new opportunities for their biotechnological applications. Thermophilic organisms are one of the most favoured organisms, whose distinctive characteristics are extremely related to their cellular constituent particularly biologically active proteins. Modifications on the enzyme structure are critical in optimizing the stability of enzyme to thermophilic conditions. Thermostable lipases are one of the most favourable enzymes used in food industries, pharmaceutical field, and actively been studied as potential biocatalyst in biodiesel production and other biotechnology application. Particularly, there is a trade-off between the use of enzymes in high concentration of organic solvents and product generation. Enhancement of the enzyme stability needs to be achieved for them to maintain their enzymatic activity regardless the environment. Various approaches on protein modification applied since decades ago conveyed a better understanding on how to improve the enzymatic properties in thermophilic bacteria. In fact, preliminary approach using advanced computational analysis is practically conducted before any modification is being performed experimentally. Apart from that, isolation of novel extremozymes from various microorganisms are offering great frontier in explaining the crucial native interaction within the molecules which could help in protein engineering. In this review, the thermostability prospect of lipases and the utility of protein engineering insights into achieving functional industrial usefulness at their high temperature habitat are highlighted. Similarly, the underlying thermodynamic and structural basis that defines the forces that stabilize these thermostable lipase is discussed. KEY POINTS: • The dynamics of lipases contributes to their non-covalent interactions and structural stability. • Thermostability can be enhanced by well-established genetic tools for improved kinetic efficiency. • Molecular dynamics greatly provides structure-function insights on thermodynamics of lipase.

Analysis of the effect of recent reformulation strategies on the crystallization behaviour of cocoa butter and the structural properties of chocolate

Chocolate is a complex soft material characterized by solid particles (cocoa powder, milk solid particles and sugar crystals) dispersed in a crystallized fat matrix mostly composed of cocoa butter (CB). Important chocolate properties such as snap, and visual appearance are strongly dependent on the internal molecular arrangement (polymorph), size and shape, as well as the spatial distribution of CB crystals within the chocolate mix. In recent years confectionary companies have put increasing effort in developing novel chocolate recipes to improve the nutritional profile of chocolate products (e.g., by reducing the amount of high saturated fat and sugar content) and to counteract the increasing price of cocoa butter as well as sustainability issues related to some chocolate ingredients. Different reformulation strategies can dramatically affect the crystallization thermodynamic and kinetic behaviour of cocoa butter; therefore, affecting the structural and sensorial properties of chocolate. In this review we analyse how different reformulation strategies affect the crystallization behaviour of cocoa butter and, hence, the structural and sensorial properties of chocolate. In particular, this work discusses the effect of: (1) CB replacement with emulsions, hydrogels, oleogels and oleofoams; (2) CB dilution with limonene or cocoa butter equivalents; (3) replacement or reduction of the amount of sugar and milk in chocolate. We found that there is certainly potential for successful novel alternative chocolate products with controlled crystalline properties; however, further research is still needed to ensure sensory acceptance and reasonable shelf-life of these novel products.

Molecular Origins of Polymorphism in Cocoa Butter

Cocoa butter displays complex crystallization behavior and six crystal polymorphic forms. Although the crystal structure of cocoa butter has been studied extensively, the molecular interactions between cocoa butter triacylglycerols in relation to polymorphic transformations from metastable forms (forms III and IV) to stable crystal forms (forms V and VI) remain largely unknown. In this review, the triclinic polymorphism and melting profiles of the major triacylglycerols in cocoa butter-POP, POS, and SOS-are reviewed, and their binary and ternary phase behaviors in metastable (pseudoβ') and stable (β₂) crystal forms are discussed. We also attempt to clarify how the transformation of cocoa butter from form IV to V, as a critical step in the tempering of chocolate, is controlled by POS interactions with both POP and SOS. Moreover, we show how the crystal forms V and VI of cocoa butter are templated by crystal forms β₃ and β₁ of POS, respectively.