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Sorghum malt-based weaning food formulations

Sorghum malt-based weaning food formulations: Preparation, functional

properties, and nutritive value

Karuna D. Kulkarni, D. N. Kulkarni, and U. M. Ingle

Abstract

The high-volume/high-viscosity character of many commercially available weaning

foods is a major constraint in providing children with enough calorie density. An

attempt was made to formulate low-cost, nutritive but bulk-reduced weaning foodsusing sorghum malt, green gram malt, and sesame flour. The formulations thus

prepared were evaluated for functional properties such as particle size, waterabsorption, dispersibility, hot-paste and cold-paste viscosities, colour, and nutritive

value with respect to calories, vitamin C, minerals, and available lysine. The

ingredients showed variation in particle size: green gram malt was finer thansorghum malt, and sesame flour was much coarser. The laboratory formulations had

finer particle size than a commercial sample. Green gram malt had a higher water-

absorption capacity and a lower percentage of dispersibility in water than sorghummalt. The experimental formulations had lower water-absorption capacities and

higher percentages of dispersibility than the commercial sample. The viscosities of10% and 15% gruel concentrations of the experimental formulations were muchlower than those of the commercial sample. CSH-I sorghum malt was darker than the

other ingredients. Sensory evaluation found the experimental preparations to have

good acceptability. A weaning food containing 60% sorghum malt, 30% green grammalt, and 10% sesame flour was found to have satisfactory functional characteristics

and nutritive value and is recommended.

Editorial note

The combination of a cereal with an appropriate proportion of an oilseed meal or one

or more legumes to make a weaning food of acceptable organoleptic and nutritionalproperties has ample precedent. Every developing country should ensure the

availability of weaning food of this type, as it can be much less expensive than either

milk or commercial products, which are usually beyond the purchasing power of the


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poor. Incaparina is the prototype mixture of this type (see Food and Nutrition Bulletin

1980;2(2):1-2, 3-8). Recently there has been great interest in the application ofmalting to improve the acceptability and nutritional value of such mixtures, as

exemplified by the preceding article and others referred to in it.

It is hoped that the following article, which provides a detailed description of theprepation and evaluation of a food made up of 60% sorghum malt, 30% green gram(Phaseolus aureus Roxb.) malt, and 10% sesame flour, will focus renewed attention

on the desirability of locally based weaning foods in every developing country.

Introduction

Even though commercial weaning foods are available, most of them are priced

beyond the reach of the majority of the population in less-developed countries. Thesefoods are mostly manufactured using high technology and are sold in sophisticated

packaging.

There is a need for low-cost weaning foods which can be prepared easily in home andcommunity kitchens from locally available raw material such as sorghum, usingsimple technology that is within the reach of the general public in developingcountries and does not require sophisticated equipment, and which can be servedquickly and conveniently. Such foods can be more nutritious than commercial brands.

A significant problem with both commercial weaning foods and gruels made fromlocal materials is their dietary bulk, or high-volume/high-viscosity character: Whenthey are made with a high enough solid concentration to provide adequate caloriedensity, they tend to be thick and viscous, making them difficult for a young child toeat-especially if the child is sick and prefers a liquid gruel. Adding water to lower theconcentration of solid matter makes the gruel thinner and easier to eat but at the sametime reduces the calories per unit volume, so that it becomes difficult for the child toconsume enough volume to get the energy it needs, and feeding becomes time-consuming. It has been shown that germination or malting reduces dietary bulk andimproves the digestibility of grains [1]. Several studies on reducing the viscosity of

rice gruel [2], wheat gruels [3, 4], and germinated barley-based gruel [5, 6], and theacceptance of bulk-reduced weaning food [7] have indicated the usefulness of suchfoods.

We undertook to prepare weaning foods with sorghum, green gram, and sesame. Thesorghum and green gram were malted, and the sesame seed was used afterdecortication. The investigation had two major objectives: to test the functional


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characteristics of the experimental formulations in comparison with commercialproducts, and to evaluate their nutritive value.

Materials and methods

Materials

Sorghum grain samples, hybrid CSH-1 and pure-bred M35-1, were obtained from theAll India Coordinated Research Project on Sorghum, in Parbhani. Green gram andsesame were obtained from the local market in bulk and were cleaned, dried, andstored safely in containers.

A popular commercial brand of weaning food was used for comparison with the

experimental formulations.

Malting and experimental formulations

Sorghum malt was prepared according to the procedure standardized in our laboratory[8]. The sorghum grain was cleaned, weighed, washed, and steeped in water (1:3sorghum: water) for 18 hours so as to attain a 45% moisture level. The water waschanged every two hours and sodium benzoate was added to prevent fungal growthduring germination. The steeped grain was drained, loaded onto perforated trays linedwith muslin cloth, and covered with moist muslin. The trays were placed in a seed

germinator at 20C and 95% relative humidity for 72 hours. The germinated grain wasdried at 55C in an air-flow drier for 24 hours to reduce its moisture content from42% to 8%. The withered rootless were gently brushed off, and the malt was groundin a hammer mill. It was preserved in air-tight glass jars kept at a low temperature.


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FIG. 1. Preparation of sorghum malt-based weaning foods

Green gram malt was prepared by the procedure standardized by Malleshi and

Desikachar [9].

The steps used in the preparation of the ingredients are shown in figure 1. The variousformulations of experimental weaning foods are indicated in table 1.

Testing and evaluation

Functional characteristics

Particle-size distribution was evaluated by passing the ingredients and formulations

through an automatic standard sieve shaker. The percentage fraction of the sampleretained on each sieve was measured by weighing.

Water-absorption capacity, measured as grams of water absorbed by 100 g of solidmatter, was determined according to the procedure of Sosulski [12].

Dispersibility was measured by placing 10 g of the sample in a 100-ml stopperedmeasuring cylinder, adding distilled water to reach a volume of 100 ml, stirringvigorously, and allowing it to settle for three hours. The volume of settled particleswas subtracted from 100 and the difference reported as percentage dispersibility.

TABLE 1. Proportions of ingredients in the experimental weaning food formulations

Sorghum varietyand formulation

code

Ingredients (%)

Sorghummalt

Green grammalt

Sesame flour

CSH-1

A 70 30 0

B 70 20 10

C 60 30 10D 50 40 10

M35-1

E 70 30 0

F 70 20 10

G 60 30 10


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H 50 40 10

Enyzme activity

The amylolytic activity of the malts was determined by the procedure described by theAOAC [10] and is reported as L. Proteolytic activity was determined using themethod described by Ayre and Anderson [11] and is expressed as mg N/100 g malt.

Viscosity

The malts and the weaning food formulations were mixed uniformly in water atconcentrations of 10% and 15% and cooked slowly, first at 50C for 10 minutes andthen at 85C for 20 minutes. The gruels thus prepared were measured for hot-pasteviscosity using a Brookfield LVT model synchroelectric viscometer at 12 rpmrotational speed; the values are reported as centipoise (cp). After cooling to ambienttemperature (302C), the samples were measured for cold-paste viscosity in the sameway.

Nutritional analysis

Moisture, crude protein, crude fat, ash, and crude fibre were determined by AOACmethods. Carbohydrate content was estimated by the difference. Ascorbic acid wasestimated using 2,6-dichlorophenol indophenol dye. Iron and calcium weredetermined by the ISI procedure. Available lysine was estimated by a correctedstraight acid procedure. The energy values of the weaning food formulations weredetermined by computation and expressed in calories.

The four best formulations in terms of nutritive value and sensory quality were furtherevaluated for the biological value of their protein.

Sensory characteristics

The colour of the ingredients and weaning food formulations was evaluated bymatching the samples with a Munsell colour chart. The values are reported in Munsellnotations for hue, value, and chrome.

The weaning food formulations were reconstituted to 15% gruel concentration with7% sugar for taste, and were cooked with slow gelatinization. Sensory evaluation wascarried out by semi-trained judges using a 10-point hedonic scale rating for colour,flavour, taste, viscosity, and overall acceptability. The range method of statisticalanalysis was applied for the test of the significance to find the preferences.


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Results and discussion

Functional characteristics

Particle size

Particle size is an important feature of any granular mix that requires reconstitutionwith water. The smaller the particle size, the more surface area is available for waterabsorption. A fine powder tends to form more lumps and takes more time and energyto make a good dispersion. Very large particles make the dispersion more gritty. Anoptimum distribution of particle size is essential in order to get the best acceptability.

Table 2 indicates the particle-size distribution of the weaning food ingredients andformulations. About half of the sorghum malt particles were larger than 250 and therest were smaller. The green gram malt particles were finer than the sorghum malt,

and the sesame flour particles were all larger than 250. The commercial weaningfood sample had larger particles than the experimental formulations (about 78% of the

particles were larger than 250) and produced fewer lumps when mixed in water.

Water-absorption capacity and dispersibility

Water-absorption capacity gives an indication of the amount of water available forgelatinization. Lower absorption capacity is desirable for making thinner gruels. Thesorghum malts and sesame flour had lower absorption capacities than the green grammalt (table 3).

The experimental formulations had absorption capacities in the range of 128%-140%,while that of the commercial weaning food was significantly higher (176%).Formulations B and F-containing 70% sorghum malt, 20% green gram malt, and 10%sesame flour-had the lowest absorption capacities.

The dispersibility of a mix in water indicates its re constitutability. The higher thedispersibility, the better. The percentage dispersibility of the weaning food ingredientsranged from 63 to 79. The CSH-1 sorghum malt was superior to the other ingredients.The variation among the experimental formulations was negligible, ranging between

71 and 75. The commercial weaning food had a very poor dispersibility of only 40%.

TABLE 2. Particle sizes of the weaning food ingredients and formulations

(percentages material retained on the screen)

Sieve size (m)

250 212 150 120 106 75 67


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Ingredientes

Malts

CSH-1 51.38 4.07 8.21 28.29 2.41 4.52 0.09

M35-1 40.98 20.31 2.98 28.29 2.39 5.39 0.09

Green gram 6.42 3.42 25.54 3.42 12.61 44.93 0.51

Sesame flour 100 - - - - - -

Formulations

A 30.61 15.24 9.74 20.80 5.45 17.25 0.21

B 39.97 14.89 7.18 20.48 4.19 12.75 0.16

C 36.50 13.20 9.43 17.99 5.21 16.70 0.20

D 41.05 11.52 11.70 15.50 6.23 20.66 0.24

E 37.89 3.86 27.46 2.7 6.94 13.53 0.17

F 47.24 3.52 24.90 2.36 5 68 9.04 0.12

G 42.74 3.46 12.58 17.99 5.22 16.89 0.20

H 38.25 3.40 14.31 15.50 6.24 20.23 0.24

Commercial 78.01 5.02 7.72 8 50 0.59 0.04 0.02

TABLE 3 Water-absorption capacity and dispersibility of the weaning foodingredients and formulations

Water

absorptionb

Dispersibility (%)

Ingredients

Malts

CSH-1 118 79

M35-1 122 77

Green gram 173 63

Sesame flour 94 73

Formulations

A 139 72.8B 141 73.8

C 136 72.4

D 142 71.0

E 136 74.2

F 128 75.2


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G 133 73.8

H 140 72.0

Commercial 176 40.0

a. Grams of water absorbed per 100 g of solid matter.

Enzyme activity and viscosity

As noted earlier, viscosity is an important constraining factor in weaning foods. Thehigh viscosity of a gruel prepared from cereal-grain and legume flours is due to the

presence of starch and proteins. Starch, in particular, absorbs water on cooking,forming a gelatinous mass.

The use of malted flour reduces this dietary bulk because germination, or malting,

produces and activates amylolytic and proteolytic enzymes, which rapidly break downstarch and protein respectively into more soluble products. As the starch is brokendown by the amylolytic enzymes, its water-holding capacity is reduced, releasing thewater trapped in the gel structure and producing a more liquid gruel.

The amylolytic and proteolytic activities of the malts which are the principalingredients of the experimental weaning food formulations are reported in table 4. Ofthe two sorghum cultivars tested, the malt made from CSH-1 had the higheramylolytic activity. Proteolytic activity was greatest in the green gram malt.

As sorghum is a major source of starch in the formulations and green gram a majorsource of protein, the fact that the former has higher amylolytic and the latter higherproteolytic activity is very desirable.

TABLE 4. Amylolytic and proteolytic activities of the malts

Amylolyticactivity

( L)

Proteolytic activity(mg N/100 g)

Sorghum malt

CSH-1 104 111M35-1 99 107

Green gram malt 72 213

These enzymes act on the substrate most actively during the initial stage of cooking.


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The hot-paste and cold-paste viscosities of the cooked gruels prepared from 10% and15% slurries of the malts alone and of the weaning food formulations are reported intable 5. The green gram malt gruels had higher viscosities than the sorghum malt, aswas expected since sorghum malt has higher amylolytic activity.

Slight variations were observed among the experimental formulations due todifferences in the proportions of each ingredient. The 15% gruels in all cases hadthree to four times higher viscosities. The cold-paste viscosities were also muchhigher, because the starch retrogrades on cooling and takes up much more water,making it more viscous.

The commercial weaning food had significantly higher viscosities than theexperimental ones. At 10% gruel concentration they were approximately double thoseof the experimental formulations, and at 15% they were so high that it was difficult tomake the measurements with the viscometer used.

Nutritional analysis

The proximate analysis of the two sorghum cultivars and their malt samples did notvary significantly. Dehusking sesame seed causes reduction in crude fibre and ashcontent. The malt samples had high in vitro protein digestibility and a fair amount ofavailable lysine (3.24-4.17 g/16 g N). Green gram malt contained 49 mg vitamin C.The sesame flour was rich in calcium.

In the analysis of the experimental formulations- in which the green gram malt was

blended at 20%, 30%, and 40% and the sesame flour at 0% and 10% with the twotypes of sorghum malt (table 1)-there was a proportionate increase in protein,available lysine, and vitamin C with increase in the green gram malt (table 6). Thesamples with sesame flour had higher calcium content.

The PER values of the four best formulations in terms of nutritive value and sensoryacceptability ranged from 2.78 to 2.82, compared with 3.15 for casein.

TABLE 5. Hot-paste and cold-paste viscosities (cp) of the malts and weaning

food formulations at 10% and 15% slurry concentrations

Hot paste Cold paste

10% 15% 10% 15%

Malts

CSH-1 190 225 770 890

M35-1 150 190 610 760


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Green gram 370 2,500 1,400 1,900

Formulations

A 245 910 960 3,320

B 200 660 820 2,400

C 225 885 745 3,230

D 240 1,110 945 4,050

E 215 885 850 3,230

F 180 635 710 2,330

G 200 865 790 3,150

H 210 1,065 860 3,980

Commercial 425 a 1,990 a

a. Very thick.

TABLE 6. Nutrition composition of the weaning foods (moisture-free basis)

Ash

(%)Fat

(%)Protein

(%)Crude

fibre

(%)

Carbo-

hydrate

(%)

Energy

(kcal/100

g)

Ascorbic

acid

(mg %)

Calcium

(mg %)Iron

(mg

%)

Available

lysine

(g/16 g N)

A 2.35 2.41 15.03 2.12 80.21 361.41 23.20 100.9 11.57 3.10

B 2.33 6.67 14.56 2.02 76.44 383.06 18.29 232.1 11.37 3.18

C 2.47 6.59 16.01 2.18 76.3 381.41 21.99 237.4 11.53 3.23D 2.59 6.37 17.46 2.34 73.58 349.75 25.69 242.7 11.76 3.27

E 2.39 1.99 14.79 1.81 80.83 363.44 24.04 112.1 11.92 3.29

F 2.37 6.21 14.31 1.70 77.11 385.09 19.13 243.3 11.66 3.37

G 2.51 6.13 15.79 1.91 75.57 383.13 22.71 247.0 11.83 3.38

H 2.63 6.05 17.26 2.11 74.06 381.29 26.29 250.7 12.01 3.40

TABLE 7. Colour of the weaning food ingredients and formulations

Colour Munsellnotation

Ingredients

Malts

CSH-1 dull white 10YR 8/2


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M35-1 white 5Y 8/2

Green gram pale yellow 5Y 8/4

Sesame flour brownish yellow 10YR 6/8

Formulations

A dull white 10YR 7/2

B dull white 10YR 7/2

C dull white 10YR 7/1

D white 10YR 8/2

E white 5Y 8/3

F white 5Y 8/2

G white 5Y 8/3

H white 5Y 8/2

Commercial white 5Y 9/2

Sensory characteristics

The colour of the weaning food formulations depends on the colour of the ingredientsused (table 7). The colour of the CSH-1 sorghum malt was slightly inferior to that ofthe M35-1 because the CSH-1 grains had a slightly darker pericarp. The green grammalt was pale yellow, and the sesame flour slightly brownish yellow. As sesame flourmade up only 10% of the formulations, it affected the colour less than the otheringredients. The colour of the formulations did not vary much, except that thosecontaining CSH-1 malt were slightly darker.

The sensory evaluation gave high scores for colour, flavour, taste, and overallacceptability to the formulations containing 30% or 40% green gram malt and 10%sesame flour (C, D, G, and H). The mouth feel of the formulations with 20% greengram malt (B and F) was preferable to that of the others.

Conclusions

The use of malted sorghum and green gram in weaning food formulations yields aproduct with improved functional characteristics and high nutritive value. Aformulation containing 60% sorghum malt, 30% green gram malt, and 10% sesameflour is more nutritious and has better acceptability because of reduced viscosity.


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Acknowledgement

This research was supported by the Indian Council of Agricultural Research, NewDelhi.

References

1. Brandtzaeg B, Malleshi NG, Svanberg U. Desikachar HSR, Mellander O. Dietarybulk as a limiting factor for nutrient intake in preschool children: III. Studies ofmalted flour from ragi, sorghum and greengram. J Trop Pediatr 1981; 27: 184-89.

2. Gopaldas T, Mehta P, Patil A, Gandhi H. Studies on reduction in viscosity of thickrice gruels with small quantities of an amylase-rich cereal malt. Food Nutr Bull

1986;8(4):42-47.

3. Gopaldas T, Deshpande S, John C. Studies on a wheat-based amylase-rich food.Food Nutr Bull 1988;10(3):5559.

4. John C, Gopaldas T. Reduction in the dietary bulk of soya-fortified bulgur wheatgruels with wheat-based amylase-rich food. Food Nutr Bull 1988;10(4):50-53.

5. Hansen M, Pedersen B, Munck L, Eggum BO. Weaning foods with improvedenergy and nutrient density prepared from germinated cereals: 1. Preparation and

dietary bulk of gruels based on barley. Food Nutr Bull 1989;11(2):40-45.

6. Pedersen B, Hansen M, Munck L, Eggum BO. Weaning foods with improvedenergy and nutrient density prepared from germinated cereals: 2. Nutritionalevaluation of gruels based on barley. Food Nutr Bull 1989;11(2):4652.

7. Mosha AC, Svanberg U. The acceptance and intake of bulk-reduced weaningfoods: the Luganga village study. Food Nutr Bull 1990;12(1):69-74.

8. Kulkarni KD, Jadhav RR, Ingle UM, Kulkarni DN, Acharya HS. Induced malting

of sorghum and malt utilization: 11. Standardization of malting conditions.Proceedings of the Vth Indian Convention of Food Science and Technology. Mysore:Association of Food Scientists and Technologists, CFTR, 1984.

9. Malleshi NG, Desikachar HSR. Formulation of a weaning food with low hot pasteviscosity based on malted ragi and greengram. J Food Sci Technol 1982; 19(3):193210.


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10. Association of Official Analytical Chemists. Official methods of analysis.Washington, DC: AOAC, 1980: 421.

11. Ayre CA, Anderson JA. Estimation of proteolytic activity in cereals. Can J Res1939;17:239-42.

12. Sosulski FW. Water absorption capacities of flour samples. Cereal Chem1962;39:344-49.

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