Monitoring Tempered Dark Chocolate Using Ultrasonic Spectrometry

Abstract

Ultrasonic spectrometry was used to distinguish between properly tempered and untempered commercial dark chocolate. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to characterize the polymorphic state of tempered and untempered chocolate, results that were correlated to those of ultrasonic spectrometry. Four different kinds of dark chocolate samples with different amounts of sugar (7.5-50 %), fat (30-50 %), and cocoa mass (70-90 %) were subjected to two different tempering protocols. The tempering was achieved using cocoa butter seeds under static cooling from 50 to 14°C. The ultrasonic generator and analyzer SIA-7 (V.N. Instruments) was used to monitor the crystallization process. The instrument generated a chirp signal with a bandwidth of 0.5 to 3 MHz and was set to work in a four-pathway configuration with two transducers and a center frequency of 2.25 MHz. Spectrometric analysis was carried out with chocolate samples containing 2, 4, and 6 % solid fat content (SFC). The SFC was obtained from DSC measurements. Ultrasonic signals for attenuation, reflection, and velocity were compared between tempered and untempered chocolates. It was shown that seed-tempered chocolate with 30 % sugar and 47.5 % fat attenuated 2.5 MHz of ultrasonic waves by 0.8, 1.7, and 2.0 dB/cm at 2, 4, and 6 % SFC, respectively. On the other hand, untempered chocolate attenuated the ultrasound signal by 3.5, 3.6, and 4.3 dB/cm. Furthermore, it was found that ultrasound reflection signals were stronger and ultrasonic velocity was higher in chocolates with high sugar content.

Global Small-Angle X-ray Scattering Data Analysis of Triacylglycerols in the Molten State (Part I)

“…The first X-ray diffraction experiments on TAGs were carried out by the pioneers Clarkson and Malkin in 1934 who were among the first to analyze the polymorphism of TAGs . TAG polymorphism has since been widely studied, applying various methods − such as microscopy, − infrared and Raman spectroscopies, − nuclear magnetic resonance, − differential scanning calorimetry, ,,− ultrasound measurements, − X-ray and neutron scattering methods, ,− and computer simulations. , We note that TAGsalthough overall nonpolar moleculespossess a slight amphiphilic character, for the glycerol backbone is moderately hydrophilic because of the partial charges of both the oxygen and carbon atoms of the ester bond, whereas the acyl chains are completely hydrophobic . Therefore, they undergo aggregation into ordered structures with repeat distances in the order of few nanometers.…”

The Evaluation of Dark Chocolate-Elicited Emotions and Their Relation with Physico Chemical Attributes of Chocolate

“…In literature is reported that the main cocoa butter FA are stearic acid (34.62–35.67%), oleic acid (32.18–34.43%), and palmitic acid (25.24–28.41%) [ 46 ]. The differences of the cacao mass FAs profile in literature are mainly explained by the influence of geographical origins, but not by the chocolate processing conditions [ 15 ].…”

Evaluation of High-Pressure Thermophysical Parameters of the Diacylglycerol (DAG) Oil Using Ultrasonic Waves

“…Parameters of the ultrasonic wave, propagating in a liquid, are directly affected by the thermodynamic properties of the liquid, which in turn are functions of pressure and temperature (Winkelmeyer et al 2016). Therefore, by measuring the speed of sound in liquid and ultrasonic attenuation, we can gain valuable information about the thermodynamic properties of the liquid.…”