Feasibility Study of Methods to Study Cocoa Butter Crystallization in Chocolate Model Systems

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Title: Feasibility Study of Methods to Study Cocoa Butter Crystallization in Chocolate Model Systems
Author: Hendrik, Nathaniel James
Contributor: University of Helsinki, Faculty of Agriculture and Forestry, Department of Food and Environmental Sciences
Thesis level: master's thesis
Abstract: Cocoa butter (CB) is the predominant continuous phase in chocolate systems and has a significant impact on the macroscopic properties of the end product. Conventional methods such as differential scanning calorimetry (DSC), pulsed nuclear magnetic resonance (pNMR), X-ray diffraction (XRD) and polarized light microscopy (PLM) have been used to study CB crystallization primarily in bulk. Potential of alternative techniques to study crystallization such as Raman spectroscopy and Fourier Transform infrared spectroscopy (FTIR) has been explored. The main objective of this thesis research was to study the feasibility of both conventional and alternative techniques to study CB crystallization in different matrices and in tempered conditions. Bulk fat (CB with 1%, 5% or without lecithin), suspensions (CB with 1% lecithin (on fat basis) and sucrose or inulin) and chocolates were sampled as such (non-tempered systems) subjected to a laboratory scale tempering procedure to produce tempered systems. Both non-tempered and tempered products were subjected to DSC, NMR, XRD, PLM, Raman spectroscopy, FTIR and diffusing wave spectroscopy (DWS), in which primary crystallization was monitored or long-term storage was assessed. A toolbox was developed comprising feasibility of complementary techniques and, moreover, the toolbox was used to study the effect of lecithin and bulking materials on the CB crystallization behavior. The tempering procedure was successfully validated for every sample, as proven by the melting profile at 6 hours through DSC. The determination of the solid fat content (SFC) from the raw free induction decay signal by NMR showed to be more useful than the scripted SFC, especially for bulk fat systems. XRD showed its feasibility to study fat polymorphism for both bulk matrices and suspensions, except when sucrose is present, due to its interference in short spacings. PLM could only be used for non-tempered bulk fat systems since in other systems sample preparation cannot be standardized to measure crystallinity. FTIR and Raman spectroscopy seemed to be useful complementary techniques and capable of differentiating polymorphic forms, as is also possible using XRD. DWS showed to be comparable with DSC with an additional improved deconvolution of crystallization peaks. This study resulted in a feasibility toolbox and was used to study the effect of lecithin concentration and bulking materials, where the addition of 1% lecithin concentration in bulk fat and usage of inulin in model suspensions improves the crystallization of the CB matrix.
URI: URN:NBN:fi:hulib-201712195970
Date: 2017
Subject: Cocoa butter
fat crystallization
Discipline: Food Science
Food Science
Food Science
Full text embargoed until: 2020-11-10

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