water 10-15
o
C, warm water 40-45
o
C or hot water 75-80
o
C. Chocolate filled milk powder is normally reconstituted to prepare 150
– 200 mL chocolate milk ready to drink.
6. Organoleptic properties Refer to technical instructions GI-31.107-1, September 2007, established by
Nestle with title The “InOut” test method for sensory quality control, the
organoleptic properties of chocolate filled milk powder should be as follows: typical taste of chocolate milk powder, brown to white color and typical aroma of chocolate
milk powder.
B. Cocoa
1. Cocoa Type and Manufacturing Cocoa beans are seeds found in woody plants shrubs or small tree belonging
to the genus Theobroma. Only two species of this genus, Criollo, bearing warty fruits containing white or faintly purple seeds, and Forastero, bearing smoother fruits
containing seeds of a deeper purple shade, are recognized from a commercial standpoint. Numerous hybrids containing genes of both species have recently been
developed Flament 1989 cited by Shahidi 2004 Manufacturing cocoa involves fermentation, drying, cleaning, roasting, and
milling steps. The fermentation process reduce the astringency, acidity, and bitterness of cocoa Bonvehi and Coll 1997; Luna et al. 2002 cited by Shahidi 2004. The
precursors of cocoa aroma are formed during the fermentation and dryingroasting steps. Dryingroasting contributes significantly to changes in the composition of cocoa
beans and is responsible for the development of the specific cocoa aroma due to partial degradation of cocoa components and their subsequent interactions Rohan
1969; Ziegleder and Biehl 1988; Cros et al. 1999 cited by Shahidi 2004. After fermentation cocoa beans contains about 50g of water per 100 g; therefore, drying is
also necessary to preserve beans Hor et al. 1984 cited by Shahidi 2004. Cocoa beans that contain more than 6 to 7 g of water per 100 g sample are prone to microbial
fungi and enzymatic lipoxygenase, lipase, peroxidase and polyphenol oxidase degradation Vileneuve et al. 1985 cited by Shahidi 2004. Cocoa liquor, a component
of all chocolate products, is prepared by finely grinding the nib of the cocoa bean, while cocoa powder is prepared by removing part of the cocoa butter from the liquor
Apgar and Tarka 1998; Vinson et al. 1999 cited by Shahidi 2004.
2. Cocoa Composition. Cocoa contains carbohydrate, more so as starch than sugars, but it is more common
to consider the contribution from sugars mixed with cocoa during the manufacture of chocolate. Proteins only present in small amount in cocoa. Accordingly, it is for the
sensory experience that cocoa is consumed and not for the protein contribution. Nevertheless, since cocoa is often consumed as milk chocolate, the protein
contribution will increase with milk protein, and the milk solids improve the taste of a nutritious food Knight 1999.
a. Carbohydrates Sugars
Cotyledons of fresh cocoa beans contain only 2-4 of free sugar, beside traces of others sugars and sugar alcohols, such as galactose, raffinose,
starchyose, melibiose, sorbose, mannitol, inositol, etc. The final content of these sugars varies considerably in fermented beans of various origins, most likely owing
to the type and extent of fermentation. Sucrose in well-fermented beans can decrease until near zero, whereas fructose and glucose increase correspondingly
Knight 1999. Table 2 Changes of sugar content in shell-free cocoa bean during fermentation.
Days of fermentation Sucrose
Fructose Glucose
Total Berbert 1979
2 4
6 2.48
1.22 0.07
0.01 0.09
0.16 0.54
0.54 0.07
0.04 0.49
0.12 2.74
1.49 1.20
0.80
Bracco et al. 1969 2
4 6
1.65 1.61
1.16 0.70
0.10 0.12
0.40 0.39
0.30 0.31
0.67 0.64
2.05 2.04
2.23 1.73
Totals include other minor sugars not designated Source : Knight 1999
By contrast, traditionally poorly fermented cocoa contains about 1 sucrose as shown in Table 2. Invertase was found only in the testae of unfermented beans,
but data show that sucrose is obviously hydrolysed during fermentation into glucose and fructose, but part of them might be metabolized. Reineccius et al 2
suggest that the sugars are absorbed from the pulp during fermentation. During roasting, most of the reducing sugars disappear and non-reducing decrease as
well Knight 1999. Starch
Schmieder and Keeney reported a mean value of 5.30 starch 4.5 - 7.0 for 12 lots of cocoa beans including shell representing major geographic regions of
production Table 3. Two variables, which might affect the final starch content of cocoa beans, are fruits ripeness at harvesting and fermentation process. Starch in
cocoa beans increase progressively from 4.3 to 6.8 between 4.5 and 5.0 months, but then decreased to 6.3 at 5.5 months when pods were harvested
Knight 1999. Table 3 Starch content of cocoa beans representing regions of production.
Cocoa bean source Starch in whole dry beans including shells
Ghana Bahia
Samoa Ecuador
Venezuela Jamaica
Trinidad 7.00 ; 5.80
4.78 ; 4.86 4.77
5.51 ; 5.08 4.66 ; 5.63
4.50 4.77 ; 6.02
Source : Schmieder and Keeney 1980 cited by Knight 1999
Table 4 Starch content in various commercial products Product
Starch Starch in cocoa mass non-fat
Regular cocoa Dutched cocoa
Regular chocolate liquor Dutched chocolate liquor
Dark, Sweet chocolate Milk chocolate a
Milk chocolate b 15.5
15.9 6.9
7.0 3.1
1.1 1.3
18.6 18.9
16.3 16.3
20.4 18.3
18.2
Source : Schmieder and Keeney 1980 cited by Knight 1999
Data for starch analysed in various commercial products are shown in Table 4. When starch content was expressed as starch per unit of cocoa mass, values were
quite similar. This indicates that manufacturing processes employed in making these products did not alter the amount of cocoa starch present in cocoa beans
Knight 1999. Fibre
The dietary fibre DF fraction in a foodstuff is that part regarded as indigestible or resistant to the action of human digestive enzymes. Various methods have been
developed and applied, and in the case of cocoa, very different data were
obtained. Valiente et al. found 17.8 and 16.1 DF in raw and roasted cocoa bean, respectively; using the method according to Prosky et al. Approximately 20
of DF is soluble. Cocoa bean contains also significant amount of polyphenols 5.9, expressed as tannic acid, but very little has been found in the fibre
fractions 0.2 in soluble dietary fibre and 1.6 in insoluble dietary fibre Knight 1999.
Geilinger et al. determined the dietary fibre content using the neutral detergent method 15 and found 9.1 in fermented cocoa bean, 12.0 after roasting, and
12.1-15.4 in cocoa mass. This increase of apparent fibre during roasting and processing of the beans was probably due to condensation reaction between
protein and polyphenols. These fibre contents are, however, lower than the value reported elsewhere, in part because it does not take into account the soluble fibre
fraction Knight 1999. b. Protein
Nitrogenous compounds in cocoa beans Cocoa contains two classes of nitrogenous compounds such as proteins, which
contribute up to about 80 of total nitrogen and methylxanthines. Their quantity and relative proportion vary with the bean variety as presented in Table 5 Knight
1999. Protein modifications during cocoa processing
From the fresh beans to cocoa powder, cocoa proteins are chemically modified mainly polyphenols, which affect their functional and nutritional properties. This
reaction will contribute to reduce the solubility of the cocoa proteins, which decreases from 170 to 65 mg fat-free beans during fermentation. The protein
quality is therefore expected to decrease similarly. During roasting, the maillard reaction takes place between the amino groups of the small peptides and of the
free amino acids liberated during fermentation and the free reducing sugars, some of them also being liberated during fermentation. This maillard reaction is
responsible for the development of the cocoa aroma at the expense of the amino acids involved, and to a minor extent, of the nutritional quality Knight 1999.
c. Lipid Cocoa beans contain around 55 lipid, called cocoa butter, which comprises
predominantly stearic and oleic acids, together with a smaller contribution from palmitic acid and only traces of several other fatty acids Knight 1999.
Cocoa powder which is commercially available today contains 10-12 fat, 14- 16 fat and 20-22 fat. Cocoa powder with 10-12 fat is generally used for
beverage application, including chocolate filled milk powder. Cocoa butter is generally used in chocolate confectionary to improve taste and aroma.
Table 5 Distribution of nitrogen compounds in dry cocoa beans Bean Type
Total N Protein Nitrogen
Methylxanthine Nitrogen g100g g100g of total N Theobromine
g100g Caffeine
g100g Criollo
Trinidad 2.086
1.636 78.4
0.312 0.138
Forastero Trinidad
2.282 1.852
81.1 0.367
0.063 Forastero
West African
2.280 1.720
75.4 0.530
0.030
Source : Knight 1999
3. Cocoa Polyphenol Polyphenolic compounds comprise approximately 2 of fresh unfermented
cocoa beans Theobroma cacao Porter et al.1991 cited by Shahidi 2004. Epicatechin, catechin, epigallocatechin and epicatechin-based procyanidins have
been identified as the predominant phenolics in the flesh of fresh unfermented cocoa seeds Porter et al.1991;Thompson et al.1972;Villeneuve et al. 1989 cited
by Shahidi 2004. The following have been identified as the major flavonoids in fresh cocoa beans: a Epicatechin-4ß8-catechin procyanidin B-1, b
Epicatechin-4ß8-epicatechin procyanidin B-2, c [Epicatechin-4ß8]
2
- epicatechin procyanidin C-1, d Epicatechin-2ß5,4ß6-epicatechin, e 3T-
θ- ß-D-galactopyranosyl-ent-epicatechin-
2α7,4α8-epicatechin, f 3T-θ-ß-D- arabinopyranosyl-2
α7,4α8-epicatechin Porter et al. 1991 cited by Shahidi
2004.
Polyphenolic compounds comprise 12 to 18 of the weight of whole dry bean and are implicated in the formation of the characteristic flavor and color of
fermented cocoa Bracco et al.1969 cited by Knight 1999. Approximately 35 of polyphenol content of unfermented Forastero cocoa beans is --epicatechin
Forsyth, 1955, 1963 cited by Shahidi 2004. The purple color of unfermented cocoa beans is due to the presence of
anthocyanins, which constitute about 0.5 of the weight of defatted beans. Two main components of anthocyanin fraction of cocoa beans are 3-ß-D-galactosidyl-
cyanidins and 3- α-L-arabinosyl-cyanidins Forsyth and Quesnel, 1957 cited by
Shahidi 2004. According to Bonvehi and Coll 1998, the total content of low molecular weight
phenolics in cocoa powder, such as phenol, 2-methoxyphenol, 3-methylphenol, 4- methylphenol,
2,3-dimethylphenol, 3-ethylphenol,
4-ethylphenol, 3,4-
dimethylphenol and 3,5 dimethylphenol, should not exceed 9.6mgkg. Increased levels of these phenolic indicate contamination with smoke and contribute to the
development of smoky taste in cocoa powder, Poor drying and storage conditions are responsible for the contamination of cocoa powder with smoke. A sensorially
acceptable cocoa powder should contain no more, per kilogram of sample, than 2 mg of phenol, 0.9 mg of 3-methylphenol, 0.55 mg of 2,3-dimethylphenol, 0.9 mg of
3-ethylphenol, and 0.7 mg of 4-ethylphenol Shahidi 2004. Commercially, the degree of bean fermentation is determined by cutting 100
beans and recording the color of their cotyledons. Presence of brown color indicates that beans are fully fermented. During fermentation and subsequent
drying, flavor precursor responsible for the development of the characteristic flavor of cocoa are formed Rohan 1963,1964,1967; Rohan and Connell 1964; Rohan
and Stewart 1967 cited by Shahidi 2004. These precursors include flavonoids catechin, epicatechin and gallocatechin, amino acids and sugars; however,
unfermented cocoa beans do not contain these aroma precursors Knapp 1937 cited by Shahidi 2004. Recently, Luna et al.2002 demonstrated the existence of
a positive correlation between polyphenol levels and bitterness and astringency of cocoa liquors and also showed that polyphenol are essential contributors to the
overall sensory characteristic of Ecuadorian cocoa liquors Shahidi 2004. Table 6 Phytochemical and polyphenolics of cocoa bean and cocoa products
Compound Dry Seeds
g100g After roasting
conching g100g
In Milk
chocolate mg100g
Flavanols Catechins
+-Catechin --Epicatechin
+-Gallocatechin +-Epigallocatechin
Leucocyanidins L1-L4
Polymeric Leucocyanidins Anthocyanins
3-
α-L-arabinosyl cyanidins 3-ß-D-galactosidyl cyanidins
3.0 1.60-2.75
0.25-0.45 2.7
2.1
–5.4 0.3
0.1 0.03-0.08
0.3-0.5 L1:0.08-0.17
0.01 0.02
Total Phenolics 13.5
Source: Ziegleder and Biehl 1999 cited by Knight 1999
During the fermentation process, anthocyanins are hydrolysed to anthocyanidins that polymerise along with simple catechins to form complex
tannins Forsyth 1963 cited by Shahidi 2004. Anthocyanins usually disappear rapidly during the fermentation process Forsyth 1952 cited by Shahidi. After 4
days of fermentation, the content of anthocyanins decreases by up to 7 of initial value. The enzymatic oxidation of - epicatechins and leucocyanidins results in
the formation of a brown color characteristic of chocolate caused by production of melanin and melanoprotein Griffiths 1957 cited by Shahidi 2004. Under
fermented beans are purple or slaty due to the presence of anthocyanin pigments, whereas fully fermented beans are quite brown. Thus, the content of anthocyanins
may be considered a good index for determining the degree of cocoa bean fermentation. Further reduction in anthocyanins content is brought about by the
drying process. Depending on the length of fermentation time, drying reduces the content of anthocyanins of beans by 13 to 44. However, although drying
unfermented beans results in loss of 79 of their anthocyanin, they still contain seven times more anthocyanin pigments than those of fermented products. A 97
loss of phenolic results from 4-day fermentation of beans followed by drying Pettipher 1986 cited by Shahidi 2004.
The fermentation and drying processes alter the content and composition of phenolic compounds. Fermented cocoa beans contain a lower amount of low
molecular weight phenolics and an enhanced content of condensed phenolics. The latter compounds are involved in protein-phenol interactions and may contribute to
the low digestibility and poor biological value of cocoa proteins Chatt 1953 cited by Shahidi 2004. Formation of the protein-phenol complex also reduces the
bitterness and astringency associated with the presence of polyphenolics and reduces the unpleasant flavors and odors in roasted beans Griffiths 1957 cited by
Shahidi 2004. On the other hand, the low molecular weight polyphenols still present in chocolate may be responsible for its astringent and bitter taste Shahidi
2004. 4. Anthocyanin
Anthocyanins are water-soluble pigments found in most species in the plant kingdom; they are responsible for the bright red skin of radishes, the red skin of
potatoes, and the dark skin of eggplants, blackberries, red and black raspberries, nectarines, peaches, blueberries, bilberries, cherries, currants, grapes,
pomegranates, cranberries and ripe gooseberries contain anthocyanins Shahidi
2004. In general, the anthocyanin content in most fruits and vegetables varies between 0.1 and 1 of dry matter content Swain and Bate-Smith 1962 cited by
Kidmose 2002. Anthocyanins are composed of an aglycone anthocyanidin, sugar, and
sometime phenolic andor minor organic acids Kidmose 2002. Most anthocyanins occur as monoglycosides and diglycosides of perlargonidin, cyaniding, peonidin,
delphinidin, petunidin, and malvidin. Meanwhile, anthocyanins assume different colors when subjected to pH variation in solutions. In addition, catechins and
epicatechins, found in different plants and in high amounts in green tea leaves, are similar in their structures to anthocyanidins; however, they are colorless. The visual
detection thresholds for selected anthocyanins are shown in Table 7 Shahidi 2004.
Table 7 Visual detection thresholds VDT for selected anthocyanins. Anthocyanin
VDT mgL Cyanidin 3-glucoside
Cyanidin 3-xylosyl-galactoside Cyanidin 3-xylosyl-glucosyl-galactoside
Cyanidin 3-sinapoyl-xylosyl-glucosyl-galactoside Cyanidin 3-feruoyl-xylosyl-glucosyl-galactoside
Cyanidin 3-sophoroside-5-glucoside Cyanidin 3-coumaroyl-sinapoyl-sophoroside-5-glucoside
1.3 0.9
2.4 0.9
0.4 3.6
2.0
Source : Adapted from Stintzing, F.C. et al. 2002, J. Agric. Food Chem., 50:6172-6182 cited by Shahidi 2004
The intensity of color, however depends also on the pH, presence of metal ions, self-association of anthocyanins Hoshino et al.1980; Mazza and Miniati
1993; Figuerido et al. 1996; Wrolsdat 2000 cited by Shahidi 2004, pigment mixtures and co pigments such as others colorless phenolic compounds Ohta et
al. 1980; Brouillard 1983; Dangles et al. 1993; Mazza and Miniati 1993 cited by Shahidi 2004, as well as processing and storage conditions temperature,sugar
content, presence of ascorbic acid and presence of oxygen, amongst others Markakis 1974; Debicki-Pospisil et al.1982; Francis 1989; Dao et al.1998;
Delgado-Vargas et al.,2000 cited by Shahidi 2004. Depending on the conditions, ascorbic acid may have positive or detrimental effects on anthocyanin stability
Sarma et al. 1997 cited by Shahidi 2004. Anthocyanins are very sensitive to changes in pH Ohta et al. 1980; Sweeny
and Iacobucci 1980; Dao et al. 1998; Mazza and Brouillard 1987 cited by Shahidi 2004. In solution, they exist in four different forms; neutral and iodized quinonoidal
base, flavylium cation or oxonium salt, the colorless pseudobase and chalcone. The flavylium cation is weak acid, and a neutral quinonoidal base behaves as a
weak acid and a weak base Brouillard 1983; Mazza and Miniati 1993 cited by Shahidi 2004. Due to the equilibrium between flavylium cation and colorless
carbinol structures, most intense red coloration of anthocyanins occurs in the pH range of 1 to 3 Shahidi 2004.
In slightly acidic solutions pH 4 to 6.5, anthocyanins undergo color fading. In this range of pH, anthocyanins rapidly transform to red or blue quinonoidal bases
as a result of rapid proton loss of any hydroxyl groups at C-4`,C-5`or C-7`. Following this, nucleophilic addition of water to anthocyanins at C-2` or C-4` results
in the formation of colorless carbinol structures and this equilibrates to the open, colorless chalcone forms. The reaction involves transferring the proton as well as
breaking or forming the C-O bond Bridle 1967; Brouillard 1982,1988; Mazza and Miniati 1993; Brouillard and Dangles 1994;; Dao et al. 1998; Timberlake and
Wrolsdat 2000 cited by Shahidi 2004. Anthocyanins also show a minimum coloration at their isoelectricpoint Markakis 1960 cited by Shahidi 2004. Shifting
the pH of anthocyanins to higher values may even bring about complete loss of color. Thus, alkaline conditions, in particular at high temperature, should be
avoided in the processing of anthocyanin-containing foods Brouillard 1982 cited by Shahidi 2004.
Stability of anthocyanins during processing depends on the composition of food anthocyanins, enzymatic systems, etc. as well as temperature, pH, level of sugar,
light, organic chemicals ascorbic acid, tartaric acid, etc and contaminations with metal ions Markakis 1982; Macheix et al. 1989; Francis 1989; Wong 1989;
Wrolstad et al. 1990; Gil et al. 1997; de Ancos et al. 2000; Wrolstad, 2000; Zabetakis et al. 2000 cited by Shahidi 2004.
The rate of anthocyanin degradation is also affected by storage temperature. A linear relationship was found between the logarithm of the rate of color loss of
anthocyanins in strawberry preserves and storage temperature Meschter 1953 cited by Shahidi 2004. Thus, the half-life of anthocyanin color in strawberry
preserves is 1h, 240h, 1300h and 11 months when stored at 100, 38, 20 and 0
o
C. Similarly, higher storage temperature also increased the loss of anthocyanins color
in orange and blackberry juices. On the other hand, storing apples at 2
o
C and 70- 80 humidity slows the loss of anthocyanins Lin et al. 1989 by Shahidi 2004.
Thus, the retention of anthocyanin color may be enhanced by lowering storage temperature of foods Shahidi 2004.
C. Iron as fortificant
