Thermogravimetric characterization of dark and milk chocolates at different processing stages
Journal of Thermal Analysis and Calorimetry
Thermogravimetric characterization of dark and milk chocolates at different processing stages
Ewa Ostrowska-Lige˛ za 0 1 2 3
Agata G o´rska 0 1 2 3
Magdalena Wirkowska-Wojdyła 0 1 2 3
Joanna Brys´ 0 1 2 3
Karolina Dolatowska- Z_ebrowska 0 1 2 3
Maltam Shamilowa 0 1 2 3
Katarzyna Ratusz 0 1 2 3
Milk fat Chocolate TG 0 1 2 3
0 Department of Ecological Chemistry, Faculty Ecology and Soil Science, Baku State University , Zahid Khalilov St. 23, 1148 Baku , Azerbaijan
1 Department of Chemistry, Faculty of Food Sciences, Warsaw University of Life Sciences , Nowoursynowska 166, 02-776 Warsaw , Poland
2 & Ewa Ostrowska-Lige ̨za
3 Division of Fats & Oils and Food Concentrates Technology, Department of Food Technology, Faculty of Food Sciences, Warsaw University of Life Sciences , Nowoursynowska 166, 02-776 Warsaw , Poland
The effect of different processing stages of dark and milk chocolate samples on their thermal properties was investigated. The ingredients of chocolates were investigated too. Thermal behavior was evaluated by means of thermogravimetry (TG) and first-derivative thermogravimetry (DTG). The measurements were made at a temperature range of 50-700 C with a heating rate of 10 C min-1. TG and DTG are thermal techniques, which have been taken advantage of research cocoa liquor, sugar, and cocoa butter in chocolates during the different processing stages. The obtained results evidenced possibility of indicating differences between milk fat and cocoa butter contribution and content of cocoa liquor and sugar which differ for dark and milk chocolates.
In many processed foods, the product structure depends not
only on the ingredient formulation but also on the
processing history of the material. This is particularly true for
chocolate molding during which the fat component (cocoa
butter for dark chocolate and cocoa butter and milk fat for
milk chocolate) solidifies [
]. Confectionery products
consist of proteins, sugars, and fats. Since the fat accounts
for almost one-third for the weight of whole chocolate, its
nature significantly determines the properties of the final
product. Hence, fat phase is considered to be responsible,
inter alia, for heat stability, mouth feel, flavor release, and
general consumer satisfaction [
There are different types of chocolates (dark, milk, and
white), according to their composition in terms of cocoa
solids, milk fat, and cocoa butter, and hence the final
products have different compositions [
]. Dark chocolates
are suspensions of sucrose and cocoa particles, coated in
phospholipids in a continuous fat phase, generally cocoa
butter, with total solid content of 65–75%. The outcome is
production of a smooth suspension of particulate solids in
cocoa butter [
]. Dark chocolate is a complex food product
in which sugar crystals and cocoa particles are surrounded
by a continuous phase of crystalline and liquid cocoa
butter. Due to the hydrophilic nature of the sugar crystals, a
small portion of emulsifier, e.g., soy lecithin or
polyglycerol polyricinoleate, is often added to improve
compatibility with the hydrophobic cocoa butter [
3, 5, 6
chocolate manufacture, tempering—a technique of
controlled pre-crystallization, is used to induce a more
thermodynamically stable polymorphic form of cocoa butter to
effect good product snap, contraction, gloss, and shelf-life
]. Important physical and functional
characteristics (i.e., texture, snap and gloss) of chocolate
products are dictated by the crystal network formed by its
constituent lipid during crystallization [
]. Quality and
stability of final products are affected by a number of
factors, such as particle size, particle size distribution, and
interaction between them, and are strictly related to the raw
materials but also to the manufacture process [
different process steps (mixing, pre-refining, refining,
conching, and tempering) of chocolate manufacture and the
different adopted process parameters can affect chocolate
properties that, in turn, determine the behavior and the
characteristics of the final product. An effective control of
the technological parameters is required in order to achieve
a constant and desirable quality of the final product
]. During chocolate manufacturing, mixtures of
sugar, cocoa, and fat are heated, cooled, pressurized, and
]. Milk chocolate is a complex rheological
system having solid particles (cocoa, milk powder, and
sugar) dispersed in cocoa butter, which represents the fat
]. The processing of milk chocolate involves
during each single step (mixing, pre-refining, refining,
conching, and tempering), modifications in its final quality
and attributes, influencing in a strong way the
microstructure of the product (aggregation, de-aggregation,
reduction in particle size, immobilization of cocoa butter,
]. In particular, milk powder with its own
physical characteristics and inner porosity may have a
significant impact on the chocolate-processing conditions
and on the physical and organoleptic properties of the final
product . A deep knowledge of the influence of single
processing stage on structural chocolate properties could be
very useful and is a starting point if it is necessary to
improve or modify final product characteristics [
Fast and sensitive methodologies of food analysis,
especially for industrial purposes, are useful tools to
determine the quality of final commercial products.
Moreover, the possibility to use always easier tools to
analyze the authenticity of the certificated food
composition is a daily challenge. Thermal analysis is recognized as
instrumental method of food analysis able to give unique
information regarding the nature of the sample or the
modifications induced by industrial processing. Books and
reviews report the applications of thermoanalytical
techniques to the food science [
]. Thermal analysis has
been extensively applied to characterize the thermal,
structural, and rheological properties of the chocolates
For this purpose, in the present work, the influence of
each process phase on thermal properties of dark and milk
chocolates and their ingredients were evaluated during the
overall manufacturing process.
The purpose of the study was to assess the thermal
properties of milk and dark chocolates, and ingredients
used in chocolates production by thermogravimetry (TG) at
nitrogen and oxygen flow.
Materials and method
Dark and milk chocolate samples were produced in Polish
confectionery factory. Cocoa butter, milk fat, sugar, and
cocoa liquor have been provided by the chocolate
manufacturer. The chocolates were produced in an industrial
plant provided of mixer, pre-refiner, refiner, conching, and
tempering machine. Dark and milk chocolate production
was made up by different steps: mixing, pre-refining,
refining, conching, tempering and cooling, demoulding,
and packing. The formulation employed for the recipe was
cocoa solids (64%) (cocoa liquor and fat-reduced cocoa
powder), sugar (35%), cocoa butter (32%), soy lecithin
(0.3%), sodium carbonate (0.02%), fiber (13%), and vanilla
extract (0.03%). The ingredients used in the milk chocolate
formulation were: sugar (58%), cocoa butter (30%), whole
milk powder (22%), whey milk powder (15%), sodium
carbonate (0.02%), fiber (2.5%), and cocoa solids (30%)
(cocoa liquor and fat-reduced cocoa powder). Experimental
samples were taken after following production phases:
refining, conching (before tempering), and packing.
Samples were stored in plastic bucket (0.5 kg capacity) at room
temperature until the analytical determinations.
The analyses were performed using a Discovery TGA (TA
Instruments) thermogravimetric analyzer. Measurements
were made under nitrogen and oxygen at a flow rate of
25 mL min-1. Samples were placed in platinum
containers. The mass of the sample loaded to the thermobalance
was varied in the range of 6–9 mg. The range of operation
was from 50 to 1000 C, and measurements were made at a
temperature range of 50–700 C with heating rates of 2, 5,
10, and 15 C min-1. TG curves were obtained for
temperature dependence on mass loss, and first-derivative data
(DTG) were calculated [
]. All analyses were
completed in triplicate.
The method has been validated on real samples at three
selected temperatures in triplicate. The experimental
extended uncertainty reached maximum 2%.
Results and discussion
Thermogravimetric curves were determined and the first
derivative for all samples was calculated. In Figs. 1, 2 and 3,
TG and DTG curves of dark and milk chocolates of different
processing stages in nitrogen with different heating rates 2, 5,
and 15 C min-1 are presented. Heating rate of 10 C min-1
50 100 150 200 250 300 350 400 450 500 550 600 650 700
was representative for analysis according to Materazzi et al.
]. Materazzi et al. [
] proved that heating rate of 10 min-1
is the best resolution for such experiments. The results of
cocoa butter, milk fat, cocoa liquor, and sugar presented in
Fig. 4 were obtained from TG and DTG analyses in nitrogen
and oxygen. The TG curve of cocoa butter in nitrogen is
characterized by only one step of decomposition (Fig. 4a).
The peak in DTG curve at the temperature of 414 C was
observed. On the TG curve for cocoa butter, one transition in
the range of 310–440 C was detected. It was due to thermal
degradation of cocoa butter [
]. Cocoa butter TG curve in
oxygen is characterized by different course. The TG curve
can be divided into four stages. First stage ranged from 50 to
290 C, second—from 290 to 335 C, third—from 335 to
420 C, and fourth—from 420 to 700 C. Different
polymorphic forms, which are typical for cocoa butter, have very
different physical properties but, upon melting, give
identical liquids. In 1966, a complete study of the polymorphic
states in cocoa butter was conducted, and the existence of the
following polymorphic forms in order of increasing stability:
I (sub-a or c), II (a), III, IV (b0), V (b), and VI was
determined. Form V (b) makes that cocoa butter remains stable for
a very long period of time at the proper storage temperature
]. On the DTG curve, four peaks were observed (Fig. 4a0).
The first peak in DTG curve was detected at the temperature
of 286 C. The TG and DTG curves of milk fat in nitrogen
and oxygen are presented in Fig. 4b, b0. The maximum
temperature of first-derivative peak of milk fat was 384 C in
Fig. 3 TG (a) and DTG (a0) curves of dark and milk chocolates of
different processing stages in nitrogen with heating rate 15 C min-1
nitrogen. The course of milk fat curve was very similar to TG
curve of cocoa butter. The profiles of the TG and DTG curves
in oxygen showed five stages of decomposition of milk fat,
with maximum temperature at 95, 296, 340, 414, and 511 C.
Sbihi et al. [
] obtained similar results by studying goat
milk fat under dry air atmosphere. Milk fat due to its structure
is polymorphic fat [
]. The fat in the liquid state reached by
rapid cooling proceeds in the form of a, slow heating, and
then solidifying causes the passage in the form of b0. Form b0
is more stable than form a. In an analogous manner, form b
from the mold b0 is created. Form b is the most stable form of
fat. There is also a fourth form c (sub-a); it is characterized by
a lower melting point than the form a and b02 and directly
converts in the form of b0 [
]. Milk fat may crystallize
taking on three different polymorphic forms: c, a, and b0. The
most stable form of the milk fat is a form of b0 and the least—
form c [
]. Szabo et al. [
] reported that the
temperature range corresponding to the first stage could be attributed
to the thermal decomposition of the unsaturated fatty acids.
The next stage phases represent the decompositions of trans
isomers of fatty acids and saturated fatty acids. The
thermogravimetric data TG and first-derivative data DTG of the
cocoa liquor under a nitrogen and oxygen are shown in
Fig. 4c, c0. The TG curves showed that cocoa liquor was
thermally unstable in nitrogen and in oxygen. The course of
the TG and DTG curves in nitrogen presented three stages of
decomposition for cocoa liquor. First stage ranged from 50 to
325 C, second—from 325 to 400 C, and third—from 400
to 700 C. The maximum temperatures at 289 and 390 C
were observed. Four stages of decomposition on TG and
DTG curves of cocoa liquor in oxygen at maximum
temperature: 253, 320, 447, and 491 C were shown.
Materazzi et al. [
] studied cocoa liquor in air flow and
obtained similar results. The cocoa liquor is a mixture of
cocoa butter, cocoa powder, cocoa solid, antioxidant flavor,
and mineral compounds. The temperature of decomposition
was corresponding with thermal degradation of ingredients
of cocoa liquor. The thermogravimetric behavior of crystal
sugar is shown in Fig. 4d, d0. In the TG curve of sugar in
nitrogen, between 220 and 700 C, continuous mass loss was
observed. In TG curve in oxygen, three stages were observed
that indicate changes in the rate of mass loss during
thermogravimetric drying. This result can be attributed to water
elimination from several sources. The type and degree of
binding are reflected by the temperature of mass loss [
According to Iqbal et al. [
], the major weight loss
(18–36%) occurred in the range of 225–325 C, which was
due to major degradation of the polysaccharide structure.
Iqbal et al. [
] studied polysaccharides with the use of
thermal analysis (TG, DTG, and DSC) in nitrogen. The DTG
curves of sugar in nitrogen and in oxygen were characterized
by two peaks at similar temperature for both gases. The first
peaks with maximum temperatures of 225 and 228 C in
nitrogen and oxygen, respectively, were followed by the
second—at 288 and 271 C (Fig. 4d0). According to
Roos et al. [
], the first event was attributed to sucrose
melting and the second event was attributed to the
elimination of volatile products (water, carbon monoxide, carbon
dioxide, and hydrogen) resulting from the degradation of
]. Due to the complex behavior of sugars
when melted, thermal decomposition reactions can occur
before or close to the melting point, and in the literature a
range of values for sucrose melting varies between 185 and
190 C, yet it never reaches 225 C [
36, 38, 40
]. The sugar’s
origin may be responsible for the wide variation of melting
points, since there are different sources (e.g., cane and beet
sugar) and manufacturing methods. These findings of
variation in sucrose melting peaks have mainly been related to
impurities or polymorphism [
36, 38, 41
]. The DTG curve in
oxygen showed peak at maximum temperature of 518 C,
which indicates the sugar sample decomposition.
The thermogravimetric data (TG) and first-derivative
data (DTG) of the three stages dark and milk chocolates
production under heating in nitrogen atmosphere are
presented in Fig. 5. Milk/dark chocolate powders are the
products after refining process, milk/dark chocolate before
tempering are the products after conching process, and
dark/milk chocolates are the final chocolate bars. The TG
curves that characterize samples of dark and milk
chocolates at different stages of production can be divided into
three steps. First stage ranged from 50 to 210 C, second—
from 210 to 350 C, and third—from 350 to 700 C.
Materazzi et al. [
] stated that, by the analysis of the
starting materials (sugar, cocoa liquor, and cocoa butter), it
is very easy to assign each TG step in the dark chocolate
curve: The first one is related to the sugar contribution, the
second step is the release of the cocoa liquor, and the final
is related to the mass loss of cocoa butter (Figs. 4 and 5). In
the second step in TG curves of all production stages, the
differences between milk and dark chocolates were
observed (Fig. 5a–c). This phenomena indicated that
amount of cocoa liquor in dark chocolate (powder, before
tempering and chocolate bar) was higher. The dark
Dark chocolate powder
Milk chocolate powder
Dark chocolate powder
Milk chocolate powder
chocolate powder TG curve showed higher rate of mass
loss at third step than others TG curves. There were no
differences in TG curves courses for different stages of
dark/milk chocolates production, except of the TG course
of dark chocolate powder. The first derivatives designated
for fats and chocolates allowed identification of chocolate
ingredients (Fig. 5a0–c0). In the case of the first peaks on
DTG curves, for all samples, a temperature ranged from
about 211–214 C. The first peak proved sugar melting.
The first peaks were more distinct for samples of milk
chocolate at every production stage than for dark chocolate
samples. Milk chocolate was characterized by higher
amount of sugar in composition. In dark chocolate (for all
stages of production) at a temperature ranged from 241 to
348 C, the first derivative exhibits the presence of cocoa
liquor, so no distinct peaks are observed for milk chocolate
in this temperature region (Fig. 5a0–c0). The third peaks on
DTG curves for all samples can be observed at temperature
ranged from about 387–391 C. The intensity of those
peaks was more distinct for dark chocolates at all of
production stages, because the content of cocoa butter was
much higher than in milk chocolate. Peaks characterizing
fat in milk chocolate do not have such a clear course.
The nitrogen-purging flow gives a clear qualitative
profile, but the quantitative interpretation of the analysis is
not allowed since inert flows depress the complete
decomposition, without a final constant mass value [
changing the atmosphere to oxygen, a final decomposition
is obtained. There were differences in the TG curves and
first derivatives for the chocolate powders, chocolate
before tempering, and the finished dark and milk chocolate,
in oxygen. The results of the samples analysis in oxygen
for the three stages of dark and milk chocolates production
are presented in Fig. 6. The shapes of TG curves showed
three stages for dark and milk chocolates of different
processing stages. The first transition was observed in the
range of 50–230 C (dark and milk chocolates), the
second—230–300 C (dark chocolate) and 230–500 C (milk
chocolate), and the third one—300–700 C (dark
chocolate), 500–700 C (milk chocolate). The mass loss occurred
with high rate for dark chocolate products than for milk
chocolate products (Fig. 6a–c). The first peaks maximum
temperature range corresponds to the thermal
decomposition of sugar on all of DTG curves (Fig. 6a0–c0). The
second transition was observed only for dark chocolates
products. The peaks course indicated that the cocoa butter
was oxidized. The DTG curves in oxygen for all dark
chocolate products showed peak at maximum temperature
range from 291 to 294 C. Peaks characterizing fat in milk
chocolate were characterized by less intensity. The third
melting transition was observed on DTG curves of milk
chocolate products. The last peaks represent the
decomposition of sugar, like in Fig. 4d0. The maximum
temperatures were observed at 493 (milk chocolate
powder), 500 (milk chocolate before tempering), and 473 C
(milk chocolate). According to Glicerina et al. [
modifications in the microstructure of milk chocolate
during the different processing steps involve deep changes in
the rheological and colorimetric parameters of product.
Rheological, textural, and thermal properties of dark
chocolate are strictly related to the different steps of the
manufacturing process [
TG and DTG are thermal techniques, which have been
taken advantage of research cocoa liquor, sugar, and cocoa
butter in chocolates during the different processing stages.
The obtained results evidenced possibility of indicating
differences between milk fat and cocoa butter and content
of cocoa liquor and sugar (differences between dark and
milk chocolates). TG and DTG investigations proved to be
useful for research showing an adulteration of chocolates,
especially fats’ adulteration.
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1. Stapley A , Tewkesbury H , Fryer P. The effects of the shear and temperature history on the crystallization of chocolate . J Am Oil Chem Soc . 1999 ; 76 ( 6 ): 677 - 85 .
2. Kerti K. Investigating isothermal DSC method to distinguish between cocoa butter and cocoa butter alternatives . J Therm Anal Calorim . 2001 ; 63 : 205 - 19 .
3. Materazzi S , De Angelis Curtis S , Vecchio Ciprioti S , Risoluti R , Finamore J . Thermogravimetric characterization of dark chocolate . J Therm Anal Calorim . 2014 ; 116 : 93 - 8 .
4. Afoakwa E , Paterson A , Fowler M , Vieira J . Characterization of melting properties in dark chocolates from varying particle size distribution and composition using differential scanning calorimetry . Food Res Int . 2008 ; 41 : 751 - 7 .
5. Garti N , Wildak NR , editors. Cocoa butter and related compounds . Urbana: AOCS publishing; 2012 .
6. Beckett ST . The science of chocolate . Cambridge: The Royal Society of Chemistry; 2000 .
7. Afoakwa E , Paterson A , Fowler M , Vieira J . Influence of tempering and fat crystallization behaviours on microstructural and melting properties in dark chocolate systems . Food Res Int . 2009 ; 42 : 200 - 9 .
8. Afoakwa E , Paterson A , Fowler M. Factors influencing rheological and textural qualities in chocolate-a review . Trends Food Sci Technol . 2007 ; 18 : 290 - 8 .
9. Servais C , Jones R , Roberts I. The influence of particle size distribution on the processing of food . J Food Eng . 2002 ; 51 : 201 - 8 .
10. Granger C , Legerb A , Bareyb P , Langendorffb V , Cansell M. Influence of formulation on the structural networks in ice cream . Int Dairy J . 2005 ; 15 : 255 - 62 .
11. Sato A , Cunha R . Effect of particle size on rheological properties of jaboticaba pulp . J Food Eng . 2009 ; 91 : 566 - 70 .
12. Baldino N , Gabriele D , Migliori M. The influence of formulation and cooling rate on the rheological properties of chocolate . Eur Food Res Technol . 2010 ; 231 : 821 - 8 .
13. Glicerina V , Balestra F , Dalla Rosa M , Bergenhsta˚l B , Tornberg E , Romani S. The influence of different processing stages on particle size, microstructure and appearance of dark chocolate . J Food Sci . 2014 ; 79 : 1359 - 65 .
14. Muller-Fischer N , Windhab E. Influence of process parameters on microstructure of food foam whipped in a rotor-stator device within a wide static pressure range . Colloids Surf A . 2005 ; 263 : 353 - 62 .
15. Baixauli R , Sanz T , Salvadora A , Fiszmana S. Influence of the dosing process on the rheological and microstructural properties of a bakery product . Food Hydrocolloid . 2007 ; 21 : 230 - 6 .
16. Pajin B , Dokic L , Zaric D , Sˇ oronja-Simovic D , Loncarevic I , Nikolic I . Crystallization and rheological properties of soya milk chocolate produced in a ball mill . J Food Eng . 2013 ; 114 : 70 - 4 .
17. Aguilera J , Stanley D. Examining food microstructure . In: deMan JM, editor. Microstructural principles of food processing and engineering . 2nd ed. Gaithersburg: Aspen Publishers Inc.; 1999 . p. 1 - 43 .
18. Aguilera J , Stanley D , Baker K . New dimensions in microstructure of food products . Trends Food Sci Technol . 2000 ; 11 : 3 - 9 .
19. Afoakwa E , Paterson A , Fowler M , Vieira J . Microstructure and mechanical properties related to particle size distribution and composition in dark chocolate . Int J Food Sci Technol . 2009 ; 44 : 111 - 9 .
20. Glicerina V , Balestra F , Dalla Rosa M , Romani S . Effect of manufacturing process on the microstructural and rheological properties of milk chocolate . J Food Eng . 2015 ; 145 : 45 - 50 .
21. Liang B , Hartel R . Effects of milk powders in milk chocolate . J Dairy Sci . 2004 ; 87 : 20 - 31 .
22. Kemp R , editor. Handbook of thermal analysis and calorimetry: from macromolecules to man-chapter 16: thermal analysis in foods and food processes . Amsterdam: Elsevier; 1999 .
23. Gabbot P , editor. Principles and applications of thermal analysis . Oxford: Wiley; 2007 .
24. Materazzi S , Vecchio S. Recent applications of evolved gas analysis by infrared spectroscopy (IR-EGA) . Appl Spectrosc Rev . 2013 ; 48 ( 8 ): 654 - 89 .
25. Materazzi S , Vecchio S. Evolved gas analysis by mass spectrometry . Appl Spectrosc Rev . 2011 ; 46 ( 4 ): 261 - 340 .
26. Materazzi S , Vecchio S. Evolved gas analysis by infrared spectroscopy . Appl Spectrosc Rev . 2010 ; 45 : 241 - 73 .
27. Materazzi S , Gullifa G , Fabiano M , Frati P , Santurro A , Scopetti M , Fineschi V , Risoluti R . New frontiers in thermal analysis. A TG/Chemometrics approach for postmortem interval estimation in vitreous humor . J Therm Anal Calorim . 2017 ; 130 : 549 - 57 .
28. Mohamad SNH , Muhamad II , Khairuddin N , Mohd Jusoh YM. Stability study of a-toc/b-CD powders obtained by microwave heating and encapsulation process . J Therm Anal Calorim . 2017 ; 130 : 1473 - 80 .
29. Albis A , Ortiz E , Suare`z A , Pinˇ eres I. TG/MS study of the thermal devolatization of Copoazu´ peels (Theobroma grandiflorum) . J Therm Anal Calorim . 2014 ; 115 : 275 - 83 .
30. Wille R , Lutton E. Polymorphism of cocoa butter . J Am Oil Chem Soc . 1966 ; 43 : 491 - 6 .
31. Sbihi H , Nehdi I , Tan C , Al-Resayes S . Characteristics and fatty acid composition of milk fat from Saudi Aradi goat . Grasas Aceites . 2015 ; 66 ( 4 ): 1 - 8 .
32. Ten Grotenhuis E , Van Aken G , Van Malssen K , Schenk H . Polymorphism of milk fat studied by differential scanning calorimetry and real-time X-ray powder diffraction . J Am Oil Chem Soc . 1999 ; 76 ( 9 ): 1031 - 9 .
33. Wright A , Hartel R , Narine S , Marangoni A . The effect of minor components on milk fat crystallization . J Am Oil Chem Soc . 2000 ; 77 ( 5 ): 463 - 75 .
34. Lopez C , Riaublanc A , Lesieur P , Bourgaux C , Keller G , Ollivon M. Definition of a model fat for crystallization-in-emulsion studies . J Am Oil Chem Soc . 2001 ; 78 ( 12 ): 1233 - 44 .
35. Szabo M , Chambre D , Iditoiu C. TG/DTG/DTA for the oxidation behaviour characterization of vegetable and animal fats . J Therm Anal Calorim . 2012 ; 110 : 281 - 5 .
36. Ducat G , Felsner M , da Costa Neto P , Quina´ia S. Development and in house validation of a new thermogravimetric method for water content analysis in soft brown sugar . Food Chem . 2015 ; 177 : 158 - 64 .
37. Iqbal M , Massey S , Akbar J , Ashraf C , Masih R . Thermal analysis of some natural polysaccharide materials by isoconversional method . Food Chem . 2013 ; 140 : 178 - 82 .
38. Ross Y , Karel M , Labuza T , Levine H , Mathlouthi M , Reid D , Shalaev E , Slade L . Melting and crystallization of sugars in highsolids systems . J Agric Food Chem . 2013 ; 61 : 3167 - 78 .
39. Kumaresan R , MoorthyBabu S. Crystal growth and characterization of sucrose single crystals . Mater Chem Phys . 1997 ; 49 : 83 - 6 .
40. Lee J , Thomas L , Jerrell J , Feng H , Cadwallader K , Schmidt S . Investigation of thermal decomposition as the kinetic process that causes the loss of crystalline structure in sucrose using a chemical analysis approach (part II) . J Agric Food Chem . 2011 ; 59 : 702 - 12 .
41. Lee J , Thomas L , Schmidt S. Investigation of the heating rate dependency associated with the loss of crystalline structure in sucrose, glucose and fructose using a thermal analysis approach (part I) . J Agric Food Chem . 2011 ; 59 : 684 - 701 .
42. Glicerina V , Balestra F , Dalla Rosa M , Romani S. Rheological, textural and calorimetric modifications of dark chocolate during process . J Food Eng . 2013 ; 119 : 173 - 9 .