JFS
S: Sensory and Nutritive Qualities of Food
Soluble Albumin and Biological Value of
Protein in Cocoa (Theobroma cacao L.)
Beans as a Function of Roasting Time
L UIS ABECIA-SORIA, NELSON H. PEZ
OA -GAR
CÍA, AND JAIME AMA
YA-FARF
AN
EZO
ARCÍA
MAY
ARFAN
ABSTRA
CT
een the extent of rroasting
oasting and the amount of extr
actable
ABSTRACT
CT:: An association has been identified betw
between
extractable
om fer
otein fr
om the cocoa bean, its nutr
itiv
e vvalue
alue
ial quality of the liquor
ocoa nibs fr
protein
from
nutritiv
itive
alue,, and the sensor
sensorial
liquor.. C
Cocoa
from
fer-pr
mented seeds ((Theobr
Theobr
oma cacao L.) w
er
e pr
ecision-r
oasted at 150 °C for 0, 30, 34, 38, 42, and 46 min and the
Theobroma
wer
ere
precision-r
ecision-roasted
protein fraction extracted. From the beginning of roasting, until minute 38, about 87% of the proteins were
extractable, but the extractability substantially decreased to 72.7% at 42 min and to 65.3% at 46 min. Both total
soluble protein determination and albumin concentration of the roasted nibs diminished slightly until minute
acter
istics w
er
e obtained for the liquor
oth total nitr
ogen and capillar
y38, when acceptable sensor
y char
wer
ere
liquor.. B
Both
nitrogen
capillary
sensory
character
acteristics
electrophoretic separation and quantification of the albumin showed that the amounts of extractable protein in
this fr
action consistently follo
w ed a cy
clic patter
n until minute 42, irr
ev
ersibly decr
easing ther
eafter
iological
fraction
follow
cyclic
pattern
irrev
eversibly
decreasing
thereafter
eafter.. B
Biological
evaluation of the protein from the cocoa nibs roasted for the various times showed that at the point that the
sensor
y rrating
ating appr
oached that of a commer
cial liquor
e vvalue
alue w
er
e still high.
sensory
approached
commercial
liquor,, the albumin content and nutr
nutritiv
itive
wer
ere
itiv
oasting it may not be necessar
y to sacr
ifice the pr
otein
The findings suggest that with moder
ate
m rroasting
moderate
ate,, unifor
uniform
necessary
sacrifice
protein
otein’’s
biological value for the sensorial attributes of chocolate in a standard commercial roast.
Keywor
ds: chocolate
otein, nutr
itiv
e vvalue
alue
oasting quality
y electr
ophor
esis
eywords:
chocolate,, soluble pr
protein,
nutritiv
itive
alue,, rroasting
quality,, capillar
capillary
electrophor
ophoresis
Introduction
B
S: Sensory & Nutritive Qualities of Food
oth technological functions and nutritional properties of chocolate may depend on the composition of the soluble protein
fraction of the roasted cocoa (Theobroma cacao L.) beans. During
ripening, fermentation, and processing, the amount of soluble protein is known to undergo alterations. Zak and Keeney (1976) have
reported that during thermal treatment, some components of the
soluble protein fraction proportionally increase in solubility while
others decrease. It has been observed that the solubility of the predominant albumin fraction increases with fermentation, while
those of the globulin, prolamin, and glutelin fractions decrease.
Roasting and conching may alter the composition of the extractable
protein, while the total amount of protein extracted decreases.
Conching for 24 h, for instance, has been reported to diminish total protein extractability to the extent that the soluble extracts contain almost exclusively albumin (Zak and Keeney 1976). Concomitantly, it has been observed that the solubility of the nonalbumin
fractions rapidly decreases to nearly zero.
During conching, Maillard reaction products are known to add
up to those from oxidation and complexation, resulting in the desired, characteristic sensory attributes such as the methylpyrazines,
along with the undesirable decrease of nutritive value of proteins
produced by the addition reactions of reducing sugars to the unsubstituted amino groups. Although the nitrogenous content of
chocolate and chocolate products is included in the total protein
content of formulated foods for labeling purposes, these products
MS 20040336 Submitted 5/21/04, Revised 8/2/04, Accepted 2/18/05. Authors
Abecia-Soria and Pezoa-García are with Dept. of Food Technology –School
of Food Engineering -State Univ. of Campinas, Campinas, Brazil. Author
Amaya-Farfan is with Dept. of Food and Nutrition, F.E.A., UNICAMP, CP
6121, CEP 13083-862, Campinas, SP, Brazil. Direct inquiries to author
Amaya-Farfan (E-mail: [email protected]).
S294 JOURNAL OF FOOD SCIENCE—Vol. 70, Nr. 4, 2005
Published on Web 4/28/2005
are normally consumed without much concern for the potential nutritive contribution of their proteins after roasting.
Because solubility, degree of denaturation, and biological value
of proteins depend on the extent of the heat treatments, it was of
interest to examine the albumin content and nutritive value of the
protein extracts of cocoa nibs roasted with high precision for different lengths of time.
Materials and Methods
Raw material and roasting
Fifteen 250-g lots of nibs (2.38 < size < 5.66 mm; testae plus germ
<5%) from dry, fermented cocoa beans of the Forastero cultivar were
acquired from Bahia, Brazil. Quality characterization and classification of the fermented beans was done by the cut test in triplicate
(100 beans per test) (ICCO 2004), and the physical composition
(cotyledon, shell, and germ), total lipids, proteins, fiber, ash, and
moisture determined.
Roasting was conducted in an electric Probat-Werke, model PRE
1, rotary roaster (Emmerich-Rhein, Germany) fitted with a precision temperature controller, at a jacket temperature of 150 ± 1 °C for
0, 30, 34, 38, 42, and 46 min. The nibs were introduced when the
temperature of the empty cavity reached the rather steady temperature of 136 °C. After the addition, a sudden drop ensued, followed
by a gradual yet noticeable increase thereafter. The gases in the
cavity then reached 143 °C, 147 °C, 150 °C, 151 °C, and 151 °C, at 30,
34, 38, 42, and 46 min, respectively. Batches were allowed to cool to
room temperature, conditioned in polyethylene bags, and stored
at –18 °C before testing, for no longer than 3 mo.
Coded liquor samples of all the roasting times, heated to 50 °C,
were presented on 2 different days to an expert with more than 7 y
of experience in consumer chocolate product development and
© 2005 Institute of Food Technologists
Further reproduction without permission is prohibited
Cocoa protein and processing . . .
Fat and pr
otein extr
action
protein
extraction
Both raw and roasted nibs were laminated in a refrigerated-cylinder pilot mill (Pilon, São Paulo, Brazil) and later hexane defatted
using a Fanem soxhlet apparatus, model 170-l, 5-L capacity (Fanem,
São Paulo, Brazil) for 20 h.
The defatted laminated nibs were ground in the above Pilon
mill into a powder (40 ␮m) for protein extraction. Isolates were obtained by solubilizing the proteins from either the raw or roasted
powder at pH 9.5 with a 0.5% NaOH solution, followed by isoelectric precipitation with the addition of 1 N HCl (to reach pH 4.5), according to a specifically determined solubility curve (Figure 1). The
solubilization, precipitation, and centrifugation (1500 × g) steps
were repeated 3 times, after which a clear, purplish-brown solution
was obtained. The isolates were then lyophilized (Edwards Supermodulyo, Manor Royal, Crawley, West Sussex, U.K.) for the determination of albumin, total protein (AOAC 1990), and amino acids and
for a rat feeding experiment.
Soluble proteins
For analysis of the soluble protein fraction, clear (0.2-␮m pore filtered) samples were injected (50 millibars, 4 s) in a Hewlett-Packard
3D CE (Waldbronn, Germany), fitted with a fused silica capillary (72
cm, 75-␮m inner dia, 25 kV, 50 mM borate running buffer, pH 9.5)
and the electrophoerograms compared with those of a bovine serum
albumin standard (Sigma Chemical Co., St. Louis, Mo., U.S.A.).
Figure 1—Protein pH solubility profile of raw, fermented
cocoa beans.
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Amino acid analyses were carried out by standard chromatographic procedure in a Thermo-Separation Products/Pickering,
model P4000/PCX3100 (Riviera Beach, Fla., U.S.A.) after 6 N HCl
acid hydrolysis for 22 h, 110 °C.
Biological assay
Forty-eight weaning male Wistar rats (CEMIB, Campinas, Brazil)
were housed in individual stainless-steel cages and adapted to the
animal quarters (automatically climatized to 22 ± 2 °C, 12-h cycles
of light) for 2 d before the feeding experiment began. Diets were
prepared according to the American Institute of Nutrition, AIN-93
(Reeves and others 1993). The vitamin mix was a gift from BASF do
Brasil (São Paulo, Brazil). The assay was the 14-d net protein ratio/
relative net protein ratio (NPR, RNPR%) (Sarwar and others 1985).
The protein contents (Nx6.25) of the diets were adjusted to 10%
with either casein or the protein concentrate, except for the proteinfree group. Unroasted cocoa beans were heated for 7 min in a pressure cooker (110 °C) before extracting to inactivate proteinaceous
anti-nutrients for the “raw” control.
Results and Discussion
T
he cut test confirmed that damaged, moldy, flat, slaty, and germinated beans were present in levels consistent with highquality raw material, whereas the number of under-fermented
beans (purplish-brown in color) reached 25% (accepted limit, 20%
to 30%; Hancock 1994). Fermented beans exhibited a physical composition of cotyledon, 84.5%; shell, 14.6%, and germ 0.9%. Total lipids, protein, fiber, total ash, other organic components, and moisture of the nibs were, respectively (wet basis), 53.65, 13.60, 5.54,
2.82, 17.18, and 7.20 g per 100 g.
Albumin solubility
Although the process followed to extract the protein was one
typically used for obtaining isolates, the extract did not exhibit the
characteristically high concentration of protein isolates (Table 1).
The nitrogen solubility curve for raw, fermented, and defatted cocoa
bean proteins (Figure 1) showed the typical profile of other vegetable proteins such as soybeans (Circle and Smith 1972; Pezoa 1985).
Roasting the nibs at 150 °C brought a diminishing effect upon
the solubility and extractability of the total protein; visible from the
start to a minor degree, the effect became clearly evident beyond
the point identified as “relative-best roasting time” (38 min, and
remaining specific conditions of the experiment). The amount of
protein extracted from the roasted beans, therefore, exhibited 2
distinct phases: phase I, which comprised the initial times up to
min 38, and phase II, which included the 2 times beyond this point
(Table 1).
It was most striking to notice the statistically significant variations of the albumin solubility with increasing heating times (Figure 2). Zak and Keeney (1976) reported that although the amount
of soluble albumin in cocoa increased with thermal processing, the
total amount of protein extracted decreased. In this study we have
found that using a carefully controlled system, it is possible to observe oscillations in the amount of extractable protein as a function
of the heating time. Although in the study of Zak and Keeney
(1976) a common roaster and whole beans were used, we used a
precision heat delivery system and small size nibs, enabling us to
monitor minor changes in protein solubility. It is conceivable that,
as a function of heating time, proteins successively associate and
dissociate through intermolecular sulfhydryl-disulfide interchange
in a partially reversible manner. Because concurrent oxygen binding by –SH groups also takes place, the critical number of –SH necessary for –S-S– links will cease to exist, eventually preventing furVol. 70, Nr. 4, 2005—JOURNAL OF FOOD SCIENCE S295
S: Sensory & Nutritive Qualities of Food
quality assurance to identify the roasting time most suitable for a
standard commercial product. The expert was asked to identify the
liquor sample with highest commercial value. Using a high-quality
liquor representative of a widely consumed commercial product
(INDECA, São Paulo, Brazil) as reference and following the approach of a ranking test (IFT 1981), the expert applied the following
descriptors: under-roasted, over-roasted, and most intense roasted
aromas and flavors, proper color, bitterness, astringency and acidity, smoked-ham, and burlap-like aromas. The expert consistently
identified the 38-min roast as that most closely approaching their
prime commercial liquor. The complete sensorial description by a
30-member panel and the acceptable ratings of a finished product
obtained from similar raw material and roasted in identical manner
(38 min) were reported elsewhere (Fadini 1998; Brito and others
2001).
Cocoa protein and processing . . .
Table 1—Relative amount of protein extracted from the raw beans, protein content of the extracts, and albumin fraction of the different protein “isolates” of cocoa nibs roasted at 150 °Ca
Heating
time (min)
0 (raw)
30
34
38
42
46
Phase
I
I
I
I
II
II
Protein
recovery (%) b
88.40
86.52
84.65
86.12
72.65
65.32
Protein content
of extract (%) b
± 0.8a
± 0.9a
± 0.3b
± 0.5a
± 0.5c
± 0.3d
61.20
58.33
57.55
57.80
48.39
46.04
Albumin fraction
of extract (%)a,b
± 0.5a
± 0.8a
± 0.6a
± 0.5a
± 0.9b
± 0.6c
35.65
45.37
34.29
40.73
28.25
18.10
± 2.54c
± 1.43a
± 1.45c
± 0.98b
± 2.01d
± 1.5e
a Means of 4 independent trials.
b All values in the same column bearing the same letter do not differ significantly by the Tukey test.
Table 2—Mean total amino acid variation (g/100 g protein) of the protein concentrates as a function of roasting timea
Time of roasting at 150 °C (min)
Amino acid
Aspartic
Threonine
Serine
Glutamic
Proline
Glycine
Alanine
Cystine
Valine
Methionine
Isoleucine
Leucine
Tyrosine
Phenylalanine
Lysine
Ammonium ion
Histidine
Arginine
Totalsb
Raw
30
11.95a
3.91a
1.46a
24.88a
2.48a
4.81a
4.14a
2.78b
7.03a
1.11a
2.80a
6.20a
3.93a
4.98a
5.96a
1.18a
1.82a
9.44a
100.85a
10.80b
3.32b
1.47a
25.12a
2.18b
4.64ab
3.84b
2.95a
6.48b
1.11a
2.46ab
5.71a
3.91a
4.87ab
5.10b
1.18a
1.86a
8.08b
95.09b
34
9.62c
2.64c
1.27b
23.90a
2.14b
4.30b
3.82b
2.84b
4.74c
1.19a
2.26ab
5.68a
3.84a
4.73ab
4.69b
1.15a
1.76a
8.63ab
89.20c
38
9.61c
2.54c
1.22b
22.23b
1.73c
3.89c
3.50b
2.53c
4.34c
1.16a
2.08b
5.21bc
3.57b
4.54ab
3.95c
1.06a
1.74a
7.93b
82.84d
42
46
6.93d
2.23d
1.01c
15.29c
1.47c
2.92d
2.96c
2.06d
3.56d
0.84b
1.57c
4.16c
2.58c
3.42b
2.55d
0.74b
1.09b
5.64c
61.07e
7.22d
2.64c
1.18bc
15.18c
1.12d
2.89d
2.94c
2.05d
4.36c
0.72b
1.54c
4.12c
2.63c
3.45b
3.01d
0.72b
1.19b
5.78c
62.74e
a Means of 2 determinations.
2 Differences were by the Tukey test. Values were calculated using the condensed amino acid’s molecular weight.
ther reversibility. Solubility at every step of the process will then
inversely depend on the size of the protein agglomerates. The phenomenon could go unnoticed if one would roast the material for
time intervals of inappropriate length, noting the albumin concentration either at its high or low points only, but consistently missing
the solubility oscillations. Controlled experimental conditions of
quadruplicate roasting and extraction trials allowed us to see that
S: Sensory & Nutritive Qualities of Food
Figure 2—Cyclic variation with time of the albumin content of the protein isolates obtained from cocoa nibs
roasted at 150 °C.
S296
JOURNAL OF FOOD SCIENCE—Vol. 70, Nr. 4, 2005
these results were reproducible (Table 1, last 2 columns). Although
this situation contrasts with that of roasting the whole beans as
done in the previously cited work, our results and theirs do agree in
the sense that if roasting is performed for a sufficiently long time,
protein extractability will eventually diminish.
Because at or about 38 min of roasting under the described conditions the typical sensorial characteristics such as taste, aroma,
color, acidity, bitterness, and astringency of the liquor received a
high rating by a cocoa liquor expert, the existence of a relationship
between protein solubility and sensorial quality became evident.
The nature of the coextracted nonprotein material was not investigated but is suspected to be largely phenolic. The albumin extracts exhibited a purplish-brown tint, common to high-molecularweight phenolic compounds, whereas the presence of any
appreciable amounts of alkaloids would be unlikely and not expected from the reasonable agreement found between the
Kjeldahl and the amino acid data (amino acid total versus % protein, raw beans, Table 2).
Phenolic compounds are known to both react and physicochemically interact with proteins (Zak and Keeney 1976; Fishman and
Neucere 1980; Barel and others 1983; Butler and others 1984) in
such ways as to produce complex structures with desirable sensorial and health attributes. From the standpoint of the albumin subfraction, UV-spectral analysis performed simultaneously with the
electrophoresis showed a characteristic absorption peak at 265nm,
which was not exhibited by the bovine serum albumin peak, thereURLs and E-mail addresses are active links at www.ift.org
Cocoa protein and processing . . .
by confirming the presence of polyphenolic compounds as part of
this protein fraction. It was evident, however, that while such complexation was rather stable, there was no apparent effect on the
albumin’s electrophoretic mobility.
Table 1 also shows that the protein contents of the isolates did not
reach values above 61%, even in the unroasted bean, possibly due
to the characteristic complexation of proteins with polyphenols and
perhaps some polysaccharides. The total protein contents of the isolates varied insignificantly within phase I, although the differences
with those of phase II were significant. Percent protein extracted was
found to vary in a similar fashion as that of the protein content.
Even though thermal denaturation in the “dry state” (<7.5% moisture) usually proceeds more slowly than in solution, it was somewhat
surprising to verify that the loss of protein solubility did not reach a
more advanced state before minute 38. Although the actual inner
temperature of the nibs was not determined, estimates indicated that
the temperature lag was <5 °C, or sufficiently small to allow temperatures of approximately 120 °C to reach the core of the nib. These
conditions are known to cause thermal denaturation with loss of solubility of proteins for a number of seeds within a few minutes. The
fact that substantial irreversible loss of solubility was reached only
after 38 min of roasting suggests that cocoa albumins may have an
unusual initial resistance to heat denaturation. It would not be surprising if the mild complexation with phenolic compounds could
confer the protein additional stability against thermal denaturation,
as could be gathered from a recent study with gelatin (Strauss and
Gibson 2004). Because it is not known whether complexation of the
cocoa albumins with polyphenolic compounds are solely the result
of post-translational modification and protein packing in the bean or
whether it occurs partly as a result of the process of extraction, future
research could be aimed at assessing the extent to which naturally
packed polyphenols minimize the damaging effect of heat on cocoa
albumins, while in the bean.
It was noticed that the alternating low and high solubilities of the
albumin fraction (Table 1; Figure 2) did not necessarily reflect the
variations in total extractable protein, thus suggesting that this was
a phenomenon inherent to the nature of the albumin itself and not
to the other sub-fractions. Such behavior as a function of roasting
time is reminiscent of observations reported by other authors in
works with soy and peanut proteins treated at various temperatures
(Cherry and others 1975; Fukushima 1980) and may be the result
of the formation and splitting of large mass aggregates, together
with the making and breaking of disulfide bonds by means of heatcatalyzed oxidation.
Table 3—Net protein ratios (NPR) and relative net protein
ratios (RNPR) of the protein extracted from cocoa nibs
roasted (150 °C) for various times
Time of roasting (min)
Casein
Raw (0) b
30
34
38
42
46
NPRa
4.63
3.26
3.18
3.16
3.06
2.35
2.26
± 0.12a
± 0.11b
± 0.13c
± 0.10c
± 0.09c
± 0.12d
± 0.14d
RNPRa
100a
70.41b
68.68c
68.25c
66.09c
50.75d
48.81d
a Means bearing different letters within the same column different are
significantly by Tukey.
b Not roasted, but moist-heat treated at 110 °C for 7 min to inactivate growthinhibiting factors.
heated with glucose at temperatures between 100 °C and 150 °C.
These 2 are among the amino acids that showed the highest losses
after 30 min of roasting. It will be noticed that the loss in the sum
total along the time scale may have resulted from amino acid transformation into soluble Maillard products, but not into insolubles or
volatiles. The sudden decrease of the ammonium ion beyond
minute 38 was also noteworthy and could be attributed to the irreversible formation of melanoidins.
Losses of amino acids in the extractable material did not occur
necessarily according to their side-chain reactivity. The loss of lysine
and arginine was understandable because of their side-chain reactivity, yet the losses of valine, glutamic acid, threonine, or phenylalanine would only be understood if these were either free amino acids or N-terminal residues, as was the case with the fermented bean.
On the other hand, it could be seen that reactive histidine and unreactive methionine were consumed only at the final stages, when the
product developed negative sensory and nutritive characteristics.
Nutritive quality of the protein
Regardless of the amount of protein extracted at every stage of the
present study and considering clusters of roasting times (that is, 0,
30, 34, and 38-min cluster, and 42- and 46-min cluster), the dependence of the biological value of an extract from roasting time was
evident (Table 3; Figure 3). Weight gain variations clearly indicated
Table 2 shows the mean total amino acid losses from the protein
concentrates, the protein source for the biological assay. Up to
minute 38, all amino acids exhibited significant losses, with the
exception of methionine, phenylalanine, and histidine. On a percent basis, those that showed the greatest variations were valine,
threonine, lysine, and proline (between 38% and 30% of the initial
content), followed by aspartic, isoleucine, glycine, leucine, serine,
alanine, and arginine (between 25% and 11%). For the times beyond 38 min, all of the amino acids showed even greater losses,
from 25% to 50% on the average.
Various authors have reported the implication of amino acid losses during thermal treatment with aroma development (Urbanski
1992). Adrian (1993) and Brito and others (2000) mentioned the
reaction between pure glutamic acid or phenylalanine and a reducing sugar generating aromas typical of chocolate. Bertini (1989), in
turn, reported that particularly threonine and valine are capable of
developing weak and strong chocolate aromas, respectively, when
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Figure 3—Mean weight gain by groups of young Wistar rats
fed the protein isolated from cocoa nibs (upper and lower
bars denote SD). Key, from top to bottom: casein (—䉬—);
raw (—䊏—); 30 min (– –䉱– –); 34 min (—䊐—); 38 min (—䊊—
); 42 min (– –䊉– –); 46 min (—䉱—); protein-free group (—
䉫—).
Vol. 70, Nr. 4, 2005—JOURNAL OF FOOD SCIENCE S297
S: Sensory & Nutritive Qualities of Food
Amino acid variations
Cocoa protein and processing . . .
that up to 38 min, the animals were gaining weight at a rate close to
4 g for every 10 g gained by the control, casein-fed group. The phase
I cluster (0, 30, 34, and 38 min) proteins showed gradually decreasing abilities to promote growth, although differences between one
another were nonsignificant. In contrast, the cluster of 42 and 46 min
barely maintained the animals out of negative metabolism.
Considering the efficiency of extraction (Table 1), it seems reasonable to think that the solubility property varied negligibly up
until minute 38 (from 88.4% to 86.1%), signifying that few physicochemical and chemical alterations occurred in the protein during
phase I of roasting, which was consistent with the minimal repercussions in nutritive value. Meanwhile, the alterations occurring
during phase II were associated with lower solubility and lower
nutritional activity. Although the nutritive value of the residual
nitrogenous fraction (that is, not extractable from the nib) was not
evaluated, the difference between the “raw” and the roasted was
believed to be largely associated with melanoidins and other insoluble products of the Maillard reaction and, therefore, to be of marginal growth-promoting value. If this assumption were correct, the
putative RNPRs for the nibs roasted for 42 and 46 min should be
the corresponding RNPRs obtained for the extracts, corrected by
the differences in extractability.
The overall results imply that in a properly controlled roasting
system the amount of soluble protein in the nib did not significantly diminish as a function of roasting time at 150 °C until minute 38,
when the sensory attributes of the liquor approached those of an
acceptable commercial standard and 66% of the biological value
was still retained. Under such conditions, however, significant losses of biological value and solubility of the protein can be observed
from minute 42 onward. The soluble albumin in the extractable
protein fraction increased and decreased in a reproducible cyclic
fashion with roasting time, until a marked drop was eventually
observed between minutes 42 and 46. This finding could be of
technological importance, particularly for industrial roasters that
normally operate with the whole bean.
Traditionally, roasted cocoa products have been considered as
foods whose consumption is substantiated principally on their flavor attributes. More recently, however, health properties have been
pointed out for chocolate, due to their phenolic compounds, but
little emphasis has been given to the nutritional quality of its proteins. By and large, the neglect of the nutritive value of proteins in
chocolate could be based on the assumption that proteins are
mostly destroyed during roasting and conching, leaving behind
only a residual contribution. Moreover, from the standpoint of
modern food science and nutrition, the trade-off between specific nutrients and sensory attributes is by no means a closed issue,
particularly because the health properties of every processed food
need to be taken into account as new variables.
Conclusions
T
he data presented here show that unexpectedly high amounts
of the cocoa bean protein can remain soluble and nutritionally
S: Sensory & Nutritive Qualities of Food
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JOURNAL OF FOOD SCIENCE—Vol. 70, Nr. 4, 2005
active after roasting to the point of developing a standard chocolate
flavor. Therefore, it does not seem necessary to sacrifice much of the
protein’s nutritive or health value to obtain full sensorial properties.
It is evident that the biological value of chocolate proteins is not
negligible and that technological refinements, such as roasting the
cocoa in the form of relatively uniform nibs, rather than the whole
bean, could control heat transfer and preserve the nutritional or
health quality of the product.
Acknowledgments
The authors thank CNPq, FAPESP, FAEP-UNICAMP for the financial support, INDECA, SP, for the sensory ranking of the liquors, and
BASF-Brazil for the gift of the vitamin mix.
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