Investigation Rheological Behavior of Chocolate

Introduction

Chocolate was discovered in the years 250-290 after Christ in Central America.

Although it is possible that other explorers had discovered chocolate in America long before, Europeans did not learn about this delicious drink until 1521. Chocolate even became a reason for war with the arrival of the Spanish conquistadors on April 21, 1519, led by their leader Hernán Cortés that allows access to the sources of the use of cocoa powder: the Aztec king believed that he was dealing with the god Montezuma, whose return was predicted by legends for this very day and he welcomed the conquistadors by offering them to drink from a cup of gold, a bitter drink “Xocoatl” with refreshing virtues. Hernán Cortés imposed this drink on his army, noting that “one cup of this precious drink lasts the people for a whole day’s march, without the need for other food” [1-9].

The first Colombian chroniclers tell that the drink consisted of a liquid in which crushed cocoa beans, carob powder, vanilla, whole cloves, hazelnuts, almonds, pistachios, orange blossom and rose water, pepper powder, hot peppers were mixed. , cinnamon and corn puree. Everything was connected by successively pouring the drink from one container to another, then by repeated mixing, which produced a lot of foam. Later, honey, musk and amber are added to suppress the bitterness of the mixture.

Hernán Cortés decided to bring the famous seeds with him, along with other treasures, on his return to Spain. The first load of cocoa leaves with a “vento chocolatero”, the name given in Mexico to the northern breezes that favored navigation. The Italian poet Pietro Andrea Forzoni summarized its virtues: “A sweet ambrosia, source of health, spiritual support of a life full of weakness, so coveted by the immortal inhabitants of the celestial heights!”. From the tonic to the aphrodisiac, it was only one step, easily surpassed by the historian Bernard Diaz. According to him, Emperor Montezuma used to drink a cup of the precious elixir before crossing the threshold of his harem. Even Casanova and the Marquis de Sade did not forget this elixir.

Chocolate is a special group of sugary products made from cocoa beans, sugar, milk, hazelnuts, nuts. It is distinguished by a particularly fine and pleasant taste and aroma. Chocolate has a higher nutritional value (500-600 calories per 100g) than other sugary products whose value is between 300-400-500 calories per 100g. In addition to the fatty substances, carbohydrates and proteins that constitute the basis of food, chocolate also contains small amounts of theobromine, caffeine, organic acids, among which the oxalic one is in greater quantity, tanning substances, pigments, essential oils, lecithin, substances minerals [9-13].

Basic raw materials and auxiliary materials are used in the manufacture of sugary products (chocolate). So:

a) The basic raw materials are: sugar, glucose, invert sugar (a mixture of equal parts of glucose and fructose), used for the total or partial replacement of glucose, powdered milk, concentrated milk (used to obtain milk candies and caramels) , fats (cow butter, cocoa butter, margarine).

b) Auxiliary raw materials are the following: starch, fruit (in the form of jams or pastes for fillings, in the form of candied fruit, fruit in alcohol), fatty kernels of some fruits (walnut kernels, hazelnuts, apricots, peanuts), seeds oleaginous (sunflower, sesame) used to obtain halvah, lecithin (used in the manufacture of chocolate, as an emulsifier), agar-agar (gelling substance extracted from certain seaweeds, used to obtain jellies), food acids (citric, tartaric ), flavors (natural and synthetic) used for flavoring sugary products [13-20].

Material and methods

In this article we studied pure chocolate with 100% cocoa without lecithin or traces of milk in the form of chocolate chips. The chocolate was heated in a water bath with a TC-650 type thermostat and the viscosity was determined with the DV-3P rotary viscometer.

Results and discussion

Figures 1-5 represent linearization of  rheograms of chocolate samples in the range of temperatures at which they were studied.

Figure 1: Linearization of curve at temperature of 36 °C Click here to View Figure

Figure 2: Linearization curve at temperature of 38 °C Click here to View Figure

Figure 3: Linearization of  curve at temperature of 40 °C Click here to View Figure

Figure 4: Linearization of curve at temperatureof 42 °C Click here to View Figure

Figure 5: Linearization of curve at temperature of 44 °C Click here to View Figure

By linearizing the rheograms at a temperature of 36 degrees Celsius, a second-order exponential equation is obtained with the parameters A, B, C, D and the correlation coefficients r²:

η = 0 +Aexp(-log γ /-B) – Cexp(log  γ₀/-D)  (1)

The parameters of the formula by η = 0 +Aexp(-log γ /-B) – Cexp(log  γ₀/-D) are given in table 1.  

Table 1: Parameters formula η = 0 +Aexp(-log γ /-B) – Cexp(log  γ₀/-D)

Temperature, °C	Parameters formula η = 0 +Aexp(-log γ /-B) – Cexp(log  γ0/-D)					r2
		A	B	C	D
36	0	8.97702	-6.90885	-7.79546	-6.77266E98	0.99998
38	0	8.01267	-6.26559	-6.86225	-8.13906E128	0.99997
40	0	7.97132	-6.25213	-6.83903	-6.01613E126	0.99996
42	0	8.10352	-6.36933	-6.98847	-7.98198E125	0.99995
44	0	8.40778	-6.61737	-7.30339	-3.64452E132	0.99992

 

By linearizing the rheograms at a temperature of 36 degrees Celsius, a polynomial formula is obtained with the parameters A, B and C and the correlation coefficients r² [13]:

log η = A + Blog γ + C log γ²                               (2)

The parameters of the formula log η = A + Blog γ + C log γ²  are given in table 2.

Table 2: Parameters formula  log η = A + Blog γ + C log γ²

Temperature, °C	Parameters formula log η = A + Blog γ + C log γ2			r2
	A	B	C
36	1.18027	1.30368	0.09853	0.99996
38	1.14892	1.28409	0.1074	0.99994
40	1.1303	1.28027	0.10845	0.99992
42	1.1132	1.27747	0.10598	0.99991
44	1.10281	1.27560	0.10138	0.99988

 

Conclusions

Chocolate has a non-Newtonian behavior in the temperature range in which it was studied.. The two equations that describe the rheological behavior of chocolate have correlation coefficients close to unity. In this article we studied chocolate with 100% cocoa without lecithin and traces of milk in the form of chips. The data obtained are in accordance with those obtained from the specialized literature.

Acknowledgement

The author would like to thank, (Insert university name and Dept. name) for their guidance and support to complete this article.

Conflict of Interest

The authors do not have any conflict of interest.

References

1. Wells M.,  2009,  Science and Technology of Enrobed and Filled Chocolate, Confectionery and Bakery Products (pp. 255-284). Woodhead Publishing.
   CrossRef
2. Bahari A., & Akoh C.C., 2018,  Lwt, 97, 349-354.
   CrossRef
3. Garti N., & Aserin A., 2012, Cocoa butter and related compounds (pp. 275-305). AOCS Press.
   CrossRef
4. Manasi I.,  2019, Structural basis for the rheology of molten chocolate: a multi-technique approach (Doctoral dissertation, University of Edinburgh)
5. Stanciu I. 2023. Some methods for determining the viscosity index of hydraulic oil, Indian Journal of Science & Technology, 16(4), 254-258
   CrossRef
6. Stanciu I. 2023, Rheological behavior of corn oil at different viscosity and shear rate, Oriental Journal of Chemistry, 39(2), 335-339
   CrossRef
7. Stanciu I. 2023, Rheological characteristics of corn oil used in biodegradable lubricant, Oriental Journal of Chemistry, 39(3), 592-595
   CrossRef
8. Stanciu I. 2023, Effect of temperature on rheology of corn (Zea mays) oil, Oriental Journal of Chemistry, 39(4), 1068-1070
   CrossRef
9. Afoakwa E. O., Paterson A., & Fowler M.,  2008, European Food Research and Technology, 226(6), 1259-1268.
   CrossRef
10. Stanciu I., 2021, Oriental Journal of Chemistry, 37(1), 247-249
    CrossRef
11. Stanciu I., 2021, Oriental Journal of Chemistry, 37(2), 440-443
    CrossRef
12. Stanciu I., 2021, Oriental Journal of Chemistry, 37(4), 864-867.
    CrossRef
13. Ziegler G. R., Mongia G., & Hollender R., 2001, International Journal of Food Properties, 4(2), 353-370.
    CrossRef
14. Maheshwari B., & Yella Reddy S.,  2005,  Journal of the Science of Food and Agriculture, 85(1), 135-140.
    CrossRef
15. Blanco E., Hodgson D. J., Hermes M., Besseling R., Hunter G. L., Chaikin P. M., … & Poon W. C., 2019,  Proceedings of the National Academy of Sciences, 116(21), 10303-10308.
    CrossRef
16. Afoakwa E. O., Paterson A., Fowler M., & Vieira J., 2009, International journal of food science & technology, 44(1), 162-167.
    CrossRef
17. Stanciu I., 2019, Journal of Science and Arts, 3(48), 703-708.
18. Stanciu I., 2019, Journal of Science and Arts, 4(49), 938-988.
    CrossRef
19. Stanciu I., 2011,  Journal of Science and Arts, 1, 55-58.
20. Stanciu I., 2018, Journal of Science and Arts, 18(2), 453-458

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