藉由溫度軌跡方法與熔融結晶法來探討可可脂與巧克力的熱性質與晶體成長;Thermal Properties and Crystal Growth of Cocoa Butter and Chocolate by Temperature History Method and Melt Crystalllization

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Title:	藉由溫度軌跡方法與熔融結晶法來探討可可脂與巧克力的熱性質與晶體成長;Thermal Properties and Crystal Growth of Cocoa Butter and Chocolate by Temperature History Method and Melt Crystalllization
Authors:	柯淇鏵;Ko, Chi-Hua
Contributors:	化學工程與材料工程學系
Keywords:	溫度軌跡;熔融結晶;巧克力;可可脂;T-history;Melt crystalllization;Chocolate;Cocoa butter
Date:	2019-07-25
Issue Date:	2019-09-03 12:30:37 (UTC+8)
Publisher:	國立中央大學
Abstract:	可可脂是組成巧克力的原料之一，是控制巧克力結晶的主要成分，本篇研究目的為藉由溫度軌跡方法來探討可可脂與巧克力的熱性質以及兩種樣品以該方法所產生的結晶型態做比較，將所得的熱性質應用在熔融結晶法的結晶層厚度預測，並同樣分析兩種樣品以熔融結晶法所產生的結晶型態來做研究。在熔融結晶法中我們研究樣品厚度與時間之關係與生長曲線，使用低溫差示掃描量熱法(LT-DSC)測定熔點、平衡狀態以及樣品之吸放熱峰值，並配合X射線衍射(XRD)來測定樣品的多晶型。溫度軌跡方法顯示:可可脂熔點=287.3±0.3 K，液態熱含量=3.46±0.34 kJkg-1K-1，固態熱含量=7.35±1.47 kJkg-1K-1，潛熱=30.1±1.7 kJkg-1K-1 以及固態導熱性=0.173±0.07 Wm-1K-1，而巧克力熔點=290.9±0.3 K，液態熱含量=2.92±0.94 kJkg-1K-1，固態熱含量=6.39±0.52 kJkg-1K-1，潛熱=12.3±2.6 kJkg-1K-1以及固態導熱性=0.215±0.006 Wm-1K-1。而低溫差示掃描量熱法以及X射線衍射顯示了由溫度軌跡方法所得到的可可脂和巧克力結晶型態分別為Form IV和Form V之結晶。熔融結晶法則證明了結晶層會隨著時間的增加而成長，可可脂經由熔融結晶法產生之厚度介於0.05至0.13cm之間且會生成 Form V之結晶，該結晶型態也是生產巧克力最合適的晶型，但經由相同方法所製造出之巧克力之厚度則介於0.46至1.27cm間，在同樣時間下之結晶厚度約為可可脂厚度的十倍，且會產生Form II、Form III和Form V之結晶，我們的系統用於探討熔融結晶法應用在傳統商業巧克力生產上減少退火步驟的可能性。;Cocoa butter is one of the components of chocolate. It is the key factor of affecting the polymorph of chocolate. In this research, we used temperature history method (T-history method) to calculated the thermal properties of cocoa butter and chocolate and compared the polymorph of two samples which made by T-history method. Otherwise, we used the thermal properties which calculated by T-history method to predict the crystal layer thickness of samples of melt crystallization and also analyzed polymorph of two samples. For melt crystallization, we investigate the crystal layer growth versus time curve of samples and compared with the theoretical calculation. We use low temperature differential scanning calorimetry (LT-DSC) to determine the melting point and the equilibrium state and combine with X-ray diffraction to characterize the polymorph of cocoa butter and chocolate. By using T-history method, thermal properties of cocoa butter are: melting point (Tm) = 287.3 ± 0.3 K, heat capacity of liquid state (Cpl) = 3.46 ± 0.34 kJ kg-1 K-1, heat capacity of solid state (Cps) = 7.35 ± 1.47 kJ kg-1 K-1, liquid-solid enthalpy change (ΔHls) = 30.1 ± 1.7 kJ kg-1 K-1, and thermal conductivity (ks) = 0.173 ± 0.07 W m-1 K-1 and the thermal properties of chocolate are: Tm = 290.9 ± 0.3 K, Cpl = 2.92 ± 0.94 kJ kg-1 K-1, Cps=6.39±0.52 kJ kg-1 K-1, ΔHls = 12.3 ± 2.6 kJ kg-1 K-1 and ks = 0.215 ± 0.006 W m-1 K-1. The LT-DSC and X-ray diffraction showed that the cocoa butter and chocolate made by T-history are both form IV and form V, respectively. Melt crystallization showed the crystal layer of samples would increase as time went on. The layer thickness of cocoa butter from melt crystallization was between 0.05 cm and 0.13 cm, and would produce the Form V crystal, which was the most ideal form for chocolate manufacturing. The layer thickness of chocolate made by the same process was between 0.46 cm to 1.27 cm which was ten times larger than cocoa butter. However, it generated the Form II, Form III and Form V crystals. In this research, we investigated the possibility of the application of commercial manufacturing of chocolate without the annealing process.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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