Plant Foods for Human Nutrition 41:107-116, 1991. 107 �9 1991 Kluwer Academic Publishers. Printed in the Netherlands.

Development, acceptability and nutritional value of weaning mixtures

CHARU GUPTA & SALIL SEHGAL* Department of Foods and Nutrition, Haryana Agricultural University, Hisar, 125004, India (*author for correspondence)

Received 10 April 1990; accepted with minor revisions 15 October 1990

Key words: Pearl millet, barley, green gram, amaranth grain, soaking, malting, roasting, antinutrients, protein digestibility, acceptability

Abstract. Low cost weaning mixtures were prepared by mixing (i) malted pearl millet (Penicitum typhidium L), roasted amaranth (Amaranthus sp.); roasted green gram (Vigna radiata); jaggery and (ii) malted barley (Dehusked barley); roasted amaranth grain; roasted green gram; jaggery in proportion 60 : 20 : 40 : 45 wt/wt and were nutritionally evaluated. Both the blends had a nutrient composition within the range prescribed by the Indian Standard Institute (ISI) for processed weaning foods. The processing of grains resulted in lower levels of phytic acid, polyphenols and saponins and higher in vitro protein digestibility than those of the raw grains used for preparing mixtures. Both the mixtures were acceptable to trained panelists and children.

Introduction

Protein energy malnutrition accounts for the higher infant mortality rate in India (95/1000 live births) than industrialised countries [1]. Breast milk can meet the nutritional requirements of infants for up to four months after birth. Subsequently, output diminishes and supplementary feeding has to be resorted to, in order to bridge the gap of energy and protein requirements.

The solution of the problem of malnutrition in underdeveloped countries especially India fortunately does not call for expensive protein concentrates or other factory processed foods. There is no problem of malnutrition which cannot be solved through judicious use of inexpensive local foods which are available at door steps of rural women. There is a need for low-cost weaning foods that would at least combine some of the desired characteristics of high nutrient density, low bulk property, utilization of low cost and locally available cereals and pulses and traditional processing methods that have the potential of being early adopted at home and village level [2].

The weaning food needs to be developed from locally available resources

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which are economical, easily digestible and acceptable to children. Protein enriched low cost weaning foods using cereal and pulses have been developed by various workers [3, 4]. Food legumes are good source of protein and continue to contribute significantly towards the protein content of diets of people in India and other developing countries.

The utilization of cereals and pulses for human nutrition is constrained due to inherent antinutritional factors like phytate, polyphenols, saponins, proteases, amylase inhibitors and lectins [5].

Domestic processes have been known to reduce the level of stress factors like phytic acid [6-8], polyphenols [9-11], Saponins [7, 12] of legume grains.

Keeping these facts in v!ew, two weaning foods using locally available food ingredients (pearl millet, dehusked barley, amaranth grain and green gram) were developed. They were evaluated for their nutritional charac- teristics, the extent to which antinutritional factors survive the domestic processing and finally remaining in weaning mixtures which would change the digestibility of the mixtures. Acceptability and tolerance test for both mixtures were also carried out.

Materials and methods

Materials

The seeds of barley (Karan-351) and green gram (K-851) were obtained from the Department of Plant Breeding, Haryana Agricultural University, Hisar (India). Pearl millet, amaranth grain and jaggery were procured from the market in a single lot. The grains were cleaned of dust and other extraneous materials and stored at room temperature in plastic containers.

Processing procedures

Soaking. Pearl millet and barley seeds were steeped in double amount of water at ambient temperature for 12 h.

Sprouting. The soaked seeds were wrapped in damp muslin cloth and allowed to sprout at room temperature (37 ~ for 36 h. Then the sprouts were fan-dried overnight.

Malting. Sprouted cereals were roasted in oven at 70 ~ for 2 h to develop malt aroma.

Roasting. Grains of green gram and amaranth were roasted in a skillet till

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a uniformly light brown colour was produced. The malted and the roasted ingredients were ground in a cyclone mill (mesh size 0.5 mm) separately. The flour thus obtained and powdered jaggery were thoroughly blended.

Preparation of food blends

Cereal : Legume combinations which could provide 300 Kcal, 8-9 g protein, 6.0 mg iron and 0.4 g calcium per day and an amino acid make up similar to that of egg protein was adopted. The following weaning mixtures were developed.

I. Malted pearl millet (60 g): roasted amaranth grain (20 g): roasted green gram (40 g): jaggery (45 g).

II. Malted barley (60 g): roasted amaranth grain (20 g): roasted green gram (40 g): jaggery (45 g).

Analytical tests

The weaning mixtures were analysed for moisture, total nitrogen, calorie, ash, iron and calcium by employing the standard methods [13]. A factor of 6.25 was applied to convert N into crude protein.

Tolerance and acceptability tests

Both the weaning mixtures were subjected to sensory evaluation by a ten- member trained panel by using Hedonic scale rating of 9 = like extremely to 1 = dislike extremely. Samples were rated for colour, appearance, flavour, texture, taste and overall acceptability. Acceptability scores were analysed using the mean of observations.

The formulations from each cereal: legume combination was subjected to six day feeding study. Twenty-five children aged 1 to 3 years from a Labour Colony in Hisar, Haryana were selected to be subjects. Porridge was prepared using the mixture and was served as mid-morning snack to subjects every alternate day. Any signs of unfavourable reaction or gastrointestinal upsets were likewise noted.

Cost of the product

Cost of production of each food formulation was computed according to the price of each ingredient in the local market and compared with the cost of commercial weaning foods available in the market.

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Chemical analysis

Phytic acid was extracted in 0.5 M nitric acid and determined colorimetri- cally [14]. The saponins were determined colorimetrically [15]. Total poly- phenols were extracted and estimated as tannic acid equivalent according to the Folin Denis Procedure [16, 17].

Protein digestibility (in vitro) was assessed by employing pepsin and pancreatin [18]. The nitrogen contents of sample and undigested residue were determined by the micro-Kjeldahl method [13]. The digested protein of sample was calculated by substracting residual protein from total protein of the sample:

Protein digestibility (%) = Digested protein

Total protein x 100.

Statistical analysis

The data were processed for the analysis of variance according to the standard methods of Statistical analysis [19].

Results and discussion

Nutritional value

The moisture, protein, energy, ash, iron and calcium content of the mixtures ranged from 5.90 to 6.03 percent, 9.84 to 9.95 g, 416.40 to 440.99 KCal, 3.77 to 4.32g, 17.75 to 19.42mg and 150.00 to 190.00mg per 100g, respectively (Table 1). All the ~r in both the weaning mixtures were within the ranges prescribed by ISI for processed weaning foods. A developed weaning food from soybean had 6.5 g moisture, 19.4 g protein, 1.1 g calcium and 14 mg/100 g iron [20]. On the contrary, higher amount of calcium (29.0 mg) and lower iron content (7.6 rag) have been found in another mixture [3].

A six times lower cost of the developed weaning mixtures (per day 85 g intake) was computed when compared against a commercial weaning food Cerelac (Food Specialities India Ltd).

Tolerance and acceptability tests

Mean scores of both the mixtures for the organoleptic characteristics showed non significant difference among themselves (Table 2). All the

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formulations were rated 'like moderately' by the panelist (average score of 7 on a 9-point scale).

The weaning mixtures were found to be acceptable to the infants as out of twenty-five children only three refused to take the supplement. None of the children developed any side effect such as diarrhoea or vomiting after consuming the preparation.

The weaning mixtures prepared from local foods (Cholam, bengal gram, groundnut and jaggery) were more acceptable to infants than corn soyamilk (CSM) because they were fresh [22].

Effect of processing methods

Phytic acid, polyphenols and saponins content of unprocessed mixtures ranged from 776.00 to 820.00, 670.83 to 675.00 and 2106.66 to 2280.00 mg/ 100 g, respectively. Processed mixtures had almost half the content of anti- nutrients as compared to raw mixtures (Table 3) ranging from 361.33 to 367.33, 321.66 to 335.00 and 1260.00 to 1356.66mg]100g, respectively.

The decrease in phytic acid content in both the weaning mixtures may have been due to soaking, germination and heat treatment employed in preparing the mixtures. The decrease in the level of phytic acid of food grains during soaking may be attributed to leaching out into soaking water under the concentration gradient [23].

Decrease in the level of phytic acid during soaking [6, 7], germination [24, 25], due to phytase activity in the germinating grains [26] and heat treat- ment of food legumes and cereals [8] has been reported earlier. Similarly, loss of polyphenols during soaking possibly by leaching through seed coat [7], germination of food legumes and cereals [11, 27] has been reported earlier. The loss of saponin during germination may be due to leaching of saponins into the soaking medium by simple diffusion. Enzymatic degrada- tion could be a possible explanation of saponin loss during germination which is far from established. Loss of saponins from moth beans [7], chickpea [12], blackgram and green gram [8] and rice bean [28] during germination has earlier been reported.

Reduced level of phytic acid, saponin and polyphenols in cereals and pulses signifies a better nutritional value of these foods. The in vitro protein digestibility of mixtures varied from 80.22 to 84.43 percent. Processing of cereals and pulses brought about 24.93 to 28.29 per cent increase in protein digestibility (in vitro) of the weaning mixtures.

Reduction in the contents of the antinutritional factors during malting and roasting may be partly responsible for increasing the protein digestibility. Heat processing may denature the native protein and increase the digestibility

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[29-31]. The increase in protein digestibility on roasting may also be due to destruction of trypsin inhibitor. An increase in protein digestibility after heat treatment to black gram, mungbean [8], moth bean [32] and rice bean [28] has been reported.

Improvement in protein digestibility on germination may be attributed to the modification and degradation of storage proteins. Germination has been reported to increase in vitro protein digestibility of soybean [33] chickpea, cowpea and horse gram [34] moth bean [35, 36, 32] and rice bean [28]. Germination causes mobilization of proteins with the help of proteases leading to the information of polypeptides, oligopeptides and free amino acids. Furthermore, during sprouting trypsin inhibitors, tannins, phytate etc. are catabolised leading to lower level of these antinutritional factors in legume sprouts. This may also be responsible for increasing the protein digestibility during germination.

Summary

Blends of germinated cereals and roasted legume could meet the nutritional needs of an infant providing 400 Kcal, 9-10 g protein, 17-20mg iron and 150 to 190 mg calcium, the cost of which was calculated to be 60 paise per 100 g. Domestic processing methods like malting and roasting significantly lowered phytic acid, saponin and polyphenols of weaning mixtures and improved the protein digestibility. The feeding of such locally developed weaning mixtures, if adopted, could be instrumental in raising the nutritional status of children in the developing nations.

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