Ultrasonic application as a potential alternative to tempering in dark chocolate manufacturing

Sonocrystallization;tempering;chocolate

Rosales, Eliana

关键词: Sonocrystallization;    tempering;    chocolate;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/49656/Eliana_Rosales.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

In chocolate manufacturing tempering is crucial; tempering encourages the formation of the appropriate polymorphic form in cocoa butter (Form V) which influences important physical and functional characteristics such as color, texture, gloss and shelf life. Highly sophisticated machinery has been developed to optimize this key process; however conventional systems are still disadvantageous due its high demands of energy, time and space. Chocolate manufacturing industry is continuously trying to improve existing production processes or invent new methods for manufacturing high quality chocolate to improve energy and time efficiency. Ultrasonication technologies have become an efficient tool for large scale commercial applications, such as defoaming, emulsification, extrusion, extraction, waste treatment among others. It also, has been demonstrated that sonication influences crystallization in various lipid sources and could be employed to achieve specific polymorphic conformations. The hypothesis of this research was that sonocrystallization will favor formation of polymorph V, yielding similar quality characteristics to traditional tempered chocolate. The objective was to explore the effects of ultrasound application in dark chocolate formulation and its effects on crystallization using instrumental and sensorial methods. Dark chocolate was formulated, conched, and either tempered or sonicated. Ultrasonication (20 kHz) was applied (for times ranging from 3-20 seconds) after conching, followed by molding. Samples were compared to chocolate molded after conching and chocolate that was traditionally tempered and molded. Cycling experiments were conducted. Instrumental methods included texture analysis (TA-XT2), color (Minolta Chromameter), melting characteristics (DSC), polymorph characterization (XRD), and analysis and identification of fatty acid methyl esters (GC) and aroma extracts (GCO, GC-MS). Quantitative Descriptive Analysis (QDA) methodology was used to create sensory profiles. Results indicated that ultrasound application has a significant effect on crystallization properties of dark chocolate and under optimal conditions could be utilized to achieve an appropriate polymorphic conformation (Form V). Different sonication exposure times resulted in different melting profiles and different polymorphs indicating certain timing strategies were optimal (6 s and 9 s). QDA results indicated that sonication achieved a comparable sensory profile to tempered chocolate. The presence of a “metallic” attribute was reported by panelists only in over-sonication samples. There was no significant modification of fatty acid composition as a result of over-sonication (20 s). Forty four odor-active compounds were identified by GCO and GC-MS and no differentiated off-flavor was identified. Overall, ultrasound technology can be useful for minimal processing of chocolate and could result in a reduction of the total manufacturing time, higher throughput and even lower energy expenses