Rheological, textural and calorimetric modifications of dark chocolate during process

Effect of Inulin DP on Various Properties of Sugar-Free Dark Chocolates Containing Lactobacillus paracasei and Lactobacillus acidophilus

In the present study, the effect of different polymerization degree of inulin on the quality parameters of conventional and sugar-free dark chocolate products as well as on the vitality of probiotics used in the chocolates were investigated. To produce sugar-free dark chocolates prepared with the addition of maltitol,Lactobacillus paracasei/L. acidophilusand inulin with DP higher than 23 and lower than 10 were used as probiotic and prebiotic agents, respectively. After 90 day of storage, more than 6 log cfu/25 g probiotics were observed in the chocolates produced by supplementing of 9 log cfu/25 g probiotics. Considering the probiotic level for both conventional and sugar-free dark chocolate, the highest probiotic level was observed in the samples prepared fromL. acidophilusand inulin with DP<10. In addition, inulin with DP<10 was found as more suitable in terms of rheological characteristics of the samples. Other quality parameters (texture, colour, melting profile and water activity) changed in narrow range which was allowable when compared with the control samples. Consequently, sugar-free chocolate containingL. paracaseiandL. acidophiluscould be produced which might satisfy the expectations of the consumers and appropriate to industrial production similar to conventional chocolate. The findings of the present study highlighted the importance of the selection of the most suitable prebiotic/probiotic combination for maximizing probiotic level in the chocolate products.

Influence of hydrogenated oil as cocoa butter replacers in the development of sugar-free compound chocolates: Use of inulin as stabilizing agent

The effect of the addition of inulin as a surfactant or stability agent on white compound chocolate sweetened with sucralose and Stevia was studied. Samples were stored at 7, 15 and 30°C during 100days and the influence of inulin on rheological properties, sensorial attributes, shelf-life, physical properties such as melting, crystallization and blooming were analyzed. The shelf-life of the compound chocolate with the incorporation of inulin was higher than the control sample without replacement. Compound chocolate with inulin at 10%w/w showed a dense matrix structure, reducing the size and number of fat crystals formed during storage; furthermore they presented higher values of brightness and WI. This chocolate also showed less fracturability and improved thermal properties. DSC studies revealed increased values of onset and peak temperatures and enthalpy of melting of the polymorphic form V, at higher storage temperatures, achieving greater stability against degradation processes.

The influence of different processing stages on particle size, microstructure, and appearance of dark chocolate

The effect of different process stages on microstructural and visual properties of dark chocolate was studied. Samples were obtained at each phase of the manufacture process: mixing, prerefining, refining, conching, and tempering. A laser light diffraction technique and environmental scanning electron microscopy (ESEM) were used to study the particle size distribution (PSD) and to analyze modifications in the network structure. Moreover, colorimetric analyses (L*, h°, and C*) were performed on all samples. Each stage influenced in stronger way the microstructural characteristic of products and above all the PSD. Sauter diameter (D [3.2]) decreased from 5.44 μm of mixed chocolate sample to 3.83 μm, of the refined one. ESEM analysis also revealed wide variations in the network structure of samples during the process, with an increase of the aggregation and contact point between particles from mixing to refining stage. Samples obtained from the conching and tempering were characterized by small PS, and a less dense aggregate structure. From color results, samples with the finest particles, having larger specific surface area and the smallest diameter, appeared lighter and more saturated than those with coarse particles.

PRACTICAL APPLICATION

Final quality of food dispersions is affected by network and particles characteristics. The deep knowledge of the influence of single processing stage on chocolate microstructural properties is useful in order to improve or modify final product characteristics. ESEM and laser diffraction are suitable techniques to study changes in chocolate microstructure.