Edible air-in-oil systems, also referred to as oleofoams, constitute a novel promising material for healthier, low-calorie fat replacers in confectionary products. Oleofoams can be formed by whipping oleogels, which are dispersions of fat crystals in an oil phase. Understanding how the properties of the fat crystals (i.e. size, shape, polymorphism) contained in oleogels affect the microstructure and stability of oleofoams is essential for both the efficient design and manufacture of novel food products. In this work, cocoa butterone of the main fat phases present in confectionary productions, which is responsible for pleasant texture and mouthfeel propertieswas mixed with high oleic sunflower oil and crystallized to obtain an oleogel. This was subsequently whipped to yield a stable, highly aerated oleofoam. The effect of the crystallization conditions (oleogel composition and cooling rate) on the properties of the oleogels and related oleofoams was investigated with a multi-technique characterization approach, featuring polarized light microscopy, cryogenic scanning electron microscopy, X-Ray diffraction, differential scanning calorimetry and oscillatory rheology. Oleogel crystallization was performed in a labscale vessel, and was monitored using light turbidimetry as an in situ technique. Results showed that the concentration of cocoa butter in sunflower oil was the parameter that affected most strongly the foamability and rheology of oleofoam samples. The size and shape of cocoa butter crystals within the oleogel was found to have a less significant effect, since crystals were broken or partially melted during the aeration process. Oleofoams whipped from oleogels containing 15% w/w and 22% w/w cocoa butter displayed an overrun of 200%corresponding to a calorific density reduction to one-thirdand an increase in both the elastic and viscous moduli compared to their oleogel precursor. This was explained by a structuring effect caused by the aeration process, where cocoa butter β(V) crystal nanoplatelets (CNPs) in the oleogel rearranged to stabilize 3 the air bubbles via a Pickering mechanism. Oleofoams prepared from 30% w/w cocoa butter oleogels, on the other hand, incorporated less air (overrun between 150% and 180%) and displayed a similar viscoelastic profile to their un-whipped precursors, potentially due to air incorporation being limited by the relatively high elastic modulus of the parent oleogels. Nevertheless, the calorific density of these samples was reduced by a factor of 1.6 to 2.5 compared to their full-fat analogues.

The crystallization of shea stearin was investigated both before and after pre‐treatment with silica to remove a small amount (0.7 wt%) of diacylglycerols (DAGs) and oxidized material. NMR (for solid fat content), X‐ray diffraction (XRD), polarized light microscopy, confocal Raman microscopy, and non‐isothermal, isothermal and “stop‐and‐return” differential scanning calorimetry (DSC) techniques were used. Four major polymorphs previously found with 1,3‐distearoyl‐2‐oleoyl‐sn‐glycerol (StOSt) were detected: α, γ, β′, and β; whilst evidence for a further (δ) polymorph was found by DSC and possibly XRD but not Raman spectroscopy. Isothermal crystallization of shea stearins by DSC at 20°C produced α and δ forms within 5 min which then transformed to γ. Microscope images showed that after 1 day these had transformed into β′ with a few crystals of β, with further conversion to β after one week. Silica treated samples showed a faster initial crystallization, with faster transformation or direct crystallization into δ and then γ and β′ forms. Non‐isothermal DSC also showed a faster transformation into γ from α on the subsequent remelt. However, further transformation into β appeared to occur at reasonably similar rates for both types, suggesting that DAGs have less influence on this transformation and may be excluded from higher forms. Practical applications: This paper has two main practical applications: (i) Provides knowledge and understanding of the crystallization and polymorphic behavior of commercial shea stearin, which is a widely used fat in the confectionery, cosmetic, and pharmaceutical industries. (ii) The presence of small amounts of DAGs significantly delays the crystallization process of shea stearin, particularly of the lower polymorphs.

The formulation of reduced fat chocolate has been of interest to the confectionery industry for a considerable time. It presents a challenge, as fat reduction strategies are often accompanied by poor quality of the formulated product due to an increased viscosity of the molten chocolate. This causes difficulties during processing and poor sensory properties of the final product. The addition of limonene to chocolates leads to fat reduced chocolates that are less hard and have a lower melt viscosity. This study was undertaken to shed light on the changes produced by the addition of limonene on the crystallization and microstructure of cocoa butter. Based on evidence obtained by X-ray diffraction, differential scanning calorimetry and polarized light microscopy, it is proposed that the presence of limonene enhances the production of lower polymorphic forms on cooling but accelerates the transformation to more stable polymorphic forms. This is demonstrated in the transformation of the a and b 0 IV forms in cocoa butter to form b V at early storage times (t = 0-1 week), and the transformation to form b VI at times [2-3 weeks at 20°C. There is a complex but marked effect on crystal size, mainly at early storage times.

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