Development of weaning foods based on malted, popped, and roller-dried barly and chickpea

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Development of weaning foods based on malted, popped, and roller-dried barley and chickpea

Asrat Wondimu and Nagappa G. Malleshi

The optimum conditions for malting barley and chickpea were standardized, and a malted weaning food (MWF) formulation was prepared by blending 48-hour germinated barley and 24-hour germinated chickpea flours. Decorticated barley was mixed with 7% additional water, tempered for four hours, and popped in hot sand medium. Popped barley was mixed with popped chickpea to formulate popped weaning food (PWF). Flours from decorticated and mild toasted barley and chickpea were mixed with water and the slurry was roller dried to prepare the roller-dried weaning food (RWF). The food formulations consisted of 60% processed barley, 30% chickpea, 5% skim milk powder, and 5% cane sugar. Popped and roller-dried weaning foods were mixed with 5% malted barley flour to prepare the low-dietary-bulk formulations of popped weaning food with malt (PWFM) and roller-driea weaning food with malt (RWFM). The protein content of the formulations ranged from 14.8% to 15.6%. The viscosity of the cooked paste of MWF, MWFM, and RWFM, was much lower than that of DWF and RWF at all comparable slurry concentrations. The energy content of the gruels of MWF, MWFM, and RWFM at spoon-feeding consistency was about 1.1 kcal/g. The protein efficiency ratio (2.6-3.1), biological value (93-97), true digestibility (85-87), and net protein utilization (79-84) of the formulations indicated good growth-promoting quality of the food proteins.

Introduction

Malnutrition among infants and young children is common in developing countries. The high price of proprietary weaning foods and of vegetable and animal proteins and the non-availability of low-priced nutritious foods, combined with faulty feeding practices and late introduction of supplementary foods, are mostly responsible for aggravating the disorder among children [1 ]. Protein-energy malnutrition generally occurs during the crucial transitional phase when children are weaned from liquid to semi-solid or fully adult foods. During this period, because of their rapid growth, children need nutritionally balanced, calorie-dense supplementary foods in addition to mother's milk [2, 3].

Most weaning foods marketed in developing countries are produced by roller drying or extrusion cooking. These are capital-intensive technologies, and the foods produced have a large dietary bulk that limits children's nutrient intake. It is therefore desirable to develop low-cost weaning foods from locally available resources adapting simple technologies, so that the foods can be produced by mothers, community workers, or government agencies and supplied at aL fordable prices.

One of the simple traditional technologies that are being adapted for weaning foods is the malting of cereals and legumes. Malting not only enhances their overall nutritional qualities but also allows preparation of low-bulk foods [4-8]. Barley possesses extremely good malting quality, and its protein and carbohydrates are easily digestible [9]. Chickpea is a protein-rich legume. A suitable blend of barley and chickpea makes nutritive foods.

We developed a weaning food based on barley and chickpea, adapting malting technology. We compared the physico-chemical and nutritional qualities of malted food with those of popped and roller-dried foods of similar composition.

Materials and methods

Barley (Hordeum vulgare) and chickpea (Cicer arietinum) purchased from a local market (Mysore, India) were cleaned and used for the studies. Both exhibited more than 95% germination. The grains were steeped in excess water and germinated on moist cloth at 25°C in a biological oxygen demand incubator for up to 5 days. Samples were withdrawn at 24-hour intervals, dried at 50°C in an air oven, and derooted by gentle brushing, and the malt samples were powdered in a plate mill to pass through a 60-mesh sieve [5]. The malt amylases were extracted in acetate buffer and their activity was assayed according to the method of Bernfeld [10]. The cooked paste viscosity of a 25% (w/v) slurry was determined in a Brookfield viscometer [4].

Malted weaning food

Barley 50 kg and chickpea 25 kg were washed in water and steeped in plastic containers for 16 hours, with the water changed once in 8 hours. Barley was germinated for 48 hours and green gram for 24 hours by spreading them about 3 inches thick on clean flour, and the bed was covered with moist jute bags. Water was sprayed at 12-hour intervals to keep the germinating grains moist. The sprouts were sun-dried to about 12% moisture.

The dry barley sprouts were derooted in a brushing machine and the green malt was kilned at about 60°C for 30 minutes by contact heat in an electrically heated cake roaster rotating at 60 rpm. The kilned malt was sprayed with 5% additional water, tempered for 10 minutes, and decorticated in an emery pearler [11].

The dried chickpea sprouts were dehusked and split into cotyledons simultaneously in a plate (burr) mill adjusted to about 4 mm clearance between the plates. The husk (seed coat) and rootlets were aspirated and the malt splits were kilned at about 80°C for 30 minutes, similar to barley.

Both barley and chickpea malt were pulverized in a plate mill and sifted through a 60-mesh sieve and the throughs (flour) were collected. Barley malt flour (60%), chickpea malt flour (30%), skim milk powder (5%), and sugar (5%) were blended (see FIG. 1. Flow sheet for preparing malted weaning food) to formulate a malted weaning food (MWF).

Popped weaning food

Barley was decorticated in an emery pearler [11]. The pearled barley of 10.8% moisture content was sprayed with 7% additional water (70 ml/kg barley), mixed well, equilibrated for 4 hours in a closed container with occasional mixing, and popped in sand medium heated to about 240°C [12]. The popped barley was brushed gently and passed over a vibratory screen to free it from adhering sand particles. Popped chickpea splits were prepared according to the method of Pratape and Kurien [13].

Popped barley and chickpea were pulverized in a plate mill and sieved through 60-mesh sieve. Popped barley flour, popped chickpea flour, skim milk powder, and sugar were blended (see FIG. 2. Flow sheet for preparing popped weaning food), similar to MWF, to prepare a popped weaning food (PWF).

Roller-dried weaning food

Barley decorticated in an emery pearler was toasted in a cake roaster at about 70°C for 30 minutes. Decorticated chickpea splits prepared in a legume mill [14] were toasted in an electrical cake roaster at about 65°C for 30 minutes by contact heat. Both were pulverized in a plate mill. Barley flour, chickpea flour, skim milk powder, and sugar were blended in similar proportions to that of MWF. The blend was suspended in water (30%) and homogenized in a wet grinder (Prima mill). The resultant slurry was dried over a twin roller drier adjusted to 0.05 mm clearance, rotating at 5 rpm, and heated by steam at 4.2 psi. The roller-dried weaning food (RWF) obtained in flaky form was pulverized in a hammer mill [7].

Malt-added foods

The gruels from popped and roller-dried foods had high dietary bulk. To reduce their bulk, 95 g each of the foods were mixed with 5 g barley malt [15, 16]. These were called popped weaning food with malt (PWFM) and roller-dried weaning food with malt (RWFM).

Physico-chemical determinations

The proximate composition of the foods was determined according to American Association of Cereal Chemists methods [17] and the total energy content by standard calculations. Dietary fibre content was estimated according to the method of Asp et al. [18], and the lead, copper, zinc, cadmium, and chromium contents were estimated in an atomic adsorption spectrophotometer using air acetylene flame [17]. Bulk density (g/ml) was determined by measuring the packed volume of a known weight of the sample. Viscosity at 5% to 30% (w/v) slurry concentrations was measured using a Brookfield Viscometer (LVT model) according to the method of Brandtzaeg et al. [4].

Protein quality evaluation

To determine the protein efficiency ratio (PER), net protein ratio (NPR), biological value (BV), true digestibility (TD), and net protein utilization (NPU), the diets at 10% protein levels were prepared following the Indian Standards Institution guidelines [19].

The diets also contained 1% vitaminized oil, 1% vitaminized starch, 4% salt mixture, and 9% peanut oil. Corn starch was used to dilute the protein content of the diets. Skim milk powder served as the reference protein.

To determine PER and NPR, 21-day-old weaned male albino rats (Wistar strain) weighing about 30 g were distributed in 7 groups of 10 rats each in a randomized block design. Each rat was housed in an individual cage. The weighed diets in feeding cups were moistened with warm water before feeding. Food and water were given ad libitum. The residual food was collected daily, dried in a hot air oven, and weighed. The weekly intake and changes in body weight were recorded for the four weeks and the PER was calculated [19]. To determine NPR, a group was fed a protein-free diet for 10 days [20].

For nitrogen balance studies, 4-week-old albino rats (Wistar strain) weighing about 68 g were grouped (6 rats in each group) according to a randomized block design and housed in individual metal cages fitted with steel funnels and perforated disks to facilitate collection of faeces and urine separately. Food and water were given ad libitum. Carmine 0.2% was used as a faecal marker. Thymol crystals and toluene were added as preservatives to urine. The nitrogen con tents of faecal matter and urine were determined, and the BV, TD, and NPU were calculated according to the method of Pellett and Young [20]. The data were analysed statistically using Duncan's new multiple range test.

Results and discussion

The amylase activity increased considerably on germination of barley but only marginally on germination of chickpea. The amylase activity of barley increased from 1,510 to 4,756 maltose units (MU) on 2-day germination and to 5,360 MU on S-day germination. In chickpea the activity increased from 3.6 to 8.9 MU at 2 days and to only 12.5 MU at 5 days. This was also reflected in the substantial reduction in the cooked paste viscosity of barley and a very small decrease in the viscosity of chickpea slurry on malting (see FIG. 3. Changes in amylase activity and paste viscosity of malted barley and chickpea on progressive germination).

The loss of dry matter increased considerably as germination progressed. Data on amylase activity, viscosity, and dry matter loss on malt prepared from 1- and 5-day germinated barley indicated that germination of barley for 48 hours enhanced its amylase activity substantially, resulting in a considerable reduction of viscosity without causing a great loss of dry matter.

Sprouting chickpea for about 24 hours reduces its content of flatulence-causing oligosaccharides and improves protein and carbohydrate digestibility [21]. On the basis of these considerations, barley malted for 48 hours and chickpea malted for 24 hours were used to make malted weaning foods. In addition, kilning barley (green malt) at about 65°C and chickpea at 80"C for about 45 minutes improved the taste and gave a desirable aroma without seriously affecting amylase activity. Kilning also reduced the microbial load of the product considerably [22]. To formulate low-bulk weaning foods based on finger millet [5], sorghum [6], and wheat [23], 2-day malted cereals were blended with 1-day malted legumes.

Proximate composition

The proportions of barley, chickpea, skim milk powder, and sugar for the weaning food formulations were based on the least-cost computer programme to obtain blends of essential amino acid composition similar to that recommended by FAO/ WHO/UNU [24] for children. The popped and roller-dried foods were a little fluffy and had lower bulk density than the malted foods. The protein content of the foods ranged from 14.8% to 15.6%, which is in line with Indian standards [25] and also the Codex Alimentarius Commission standards for weaning foods [26].

The fat content varied from 1.8% to 3.8% and the ash content from 2.0% to 2.2%, and the total dietary fibre of the foods ranged from 10.6% to 12.8%. The energy value of the foods was about 340 kcal/100 g. The foods could be fortified with necessary vitamins and minerals for mass feeding programmes. The levels of heavy metals were within the permissible safe levels [27]. The composition of the foods is summarized in table 1.

Viscosity

The foods reconstituted well and formed slurries of soft consistency when stirred with cold or warm water. The viscosity of popped and roller-dried foods was considerably higher than that of malted foods at all comparable slurry concentrations (see FIG. 4. Cooked paste viscosity of weaning foods those of PWF and RWF. This clearly underscores the beneficial effect of making malted cereals either a major ingredient or an adjunct (amylase-rich food) in weaning food formulations [28]. The malted cereals could be useful for therapeutic and geriatric foods also.).

The energy content of the malted slurry at spoon-feeding consistency was 1.1 kcal/g (about 30% solids), whereas it was 0.5 kcal/g (about 10%-12% solids) for popped and roller-dried foods. Therefore, to reduce the viscosity and to increase the nutrient density of these foods, they were blended with 5% barley malt.

The cooked paste viscosity of PWFM and RWFM foods was comparable to that of malted weaning food. Thus the nutrients and the energy per unit volume of MWF, PWFM, and RWFM were much higher than

TABLE 1. Proximate composition, trace element contents, and bulk density of weaning foods (per 100 g)

Components	MWF	PWF	RWF	ISI/PFA standards
Moisture	6.3	4.9	3.5	Max 10.0 [25]
Protein (N x 6.25) (g)	15.6	14.8	15.2	Min 14 [25]
Crude fat	3.8	3.8	1.8	Max 75 [25]
Total dietary fibre (g)	11.6	12.8	10.6	-
Total ash (g)	2.2	2.0	2.0	Max 5.0 [25]
Carbohydrate (g) (by difference)	56.5	61.7	66.7	Min 45 [25]
Calcium (mg)	138	131.4	131.0	Max 1000 [25]
Phosphorus (mg)	358	275.4	283.0	-
Iron (mg)	10.2	10.7	11.3	Min 10.0 [25]
Lead (ppm)	2.0	2.1	1.4	Max 2.5 [27]
Copper (ppm)	12.5	16.8	14.6	Max 30 [27]
Zinc (ppm)	37.4	48.5	42.8	Max 50 [27]
Cadmium (ppm)	0	0	0	Max 50 [27]
Chromium (ppm)	0	0	0	-
Energy (kcal)	339	340	344	-
Bulk density (g/ml)	0.72	0.53	0.42	-

MWF = malted weaning food; PWF = popped weaning food; RWF = roller-dried weaning

TABLE 2. Net protein ratio and protein efficiency ratio of weaning food formulations

Diet	Net protein ratio (NPR)				Protein efficiency ratio (PER)					PER
Diet	Average initial weight (g)	Average gain in weight (g)	Food intake (g)	Average protein intake (g)	NPR	Average initial weight (g)	Average gain in weight (g)	Food intake (g)	Average protein intake (g)	PER
MWF	38.8	32.3	108	11	3.40^a	38.8	76.8	277	39	2.59^a
PWF	38.4	42.3	112	12	4.20^b	38.4	104.4	322	34	3.05
RWF	38.5	33.9	108	11	3.57^a	38.5	91.1	309	33	2.78^a,b
PWFM	38.6	36.7	1 10	12	3.67^a	38.6	90.7	296	31	3.13^c
RWFM	38.8	34.3	110	12	3.53^a	38.8	90.7	294	31	2.96^b,c
SKMP	38.6	43.2	104	11	4.74^b	38.6	105.3	274	28	3.76^a
SEM (54 df)						+ 0.09				+ 0.08

PWFM = popped weaning food containing 5% barley malt; RWFM = roller-dried weaning food containing 5% barley malt; SKMP = skimmed milk powder.

Means of the same column followed by different letters differ significantly according to Duncan's new multiple range test (p < .05).

TABLE 3. Biological value (BV), true digestibility (TD), and net protein utilization (NPU) values of the weaning food

Diet	N intake (mg/day/rat)	N excreteda (mg/day/rat)	N balance (mg)	N retention (%)	BV	TD	NPU
MWF	215.67	34.67	181.00	83.91^a	96.57^a	87 30^a	84.59^a
PWF	223.33	39.33	184.00	82.28^a	95.38^a	86.25^a	82.28^a,b
PWFM	224.00	38.50	185.50	82.88^a,b	96.65^a	86.63	82.89^b
RWF	225.67	46.17	179.50	79.49^b	93.10^a	85.36^a	79.49^b
RWFM	221.00	40.83	180.17	81.58^a	94.15^a	86.70^a	81.60^a,b
SKMP	176.33	20.50	155.83	88.45^c	95.87^a	92.27^b	88.45^c
SEM (30 df)				0.96	+0.67	+0.81	+0.963

a. Corrected for endogenous nitrogen.

Means of the same column followed by different letters differ significantly according to Duncan's new multiple test (p < .05).

Protein quality

The PER values for the foods (2.59-3.13) were considerably higher than the minimum values (2.1) recommended for such foods by Protein Advisory Group. The PER values of PWF and PWFM were significantly higher than those of the other foods (sable 2). The NPR of PWF was also higher than those of the other foods. The BV, TD, and NPU values of food proteins were greater than 93, 85, and 79, respectively, and these values for the malted foods were slightly higher than those for the popped and roller-dried foods (sable 3). Data from nitrogen balance studies reveal the good growth-promoting quality of the formulations regardless of the treatments given to the ingredients. According to Codex Alimentarius standards, the nutritional composition of the foods indicates their suitability for young children. Similar observations on the growth-promoting qualities of weaning food mixes prepared from finger millet-green gram [5], sorghum-cowpea [6], and wheat-chickpea [23] have been reported.

Even though the nutritional advantages of barley are known, the difficulty of preparing decorticated, low-fibre barley limits its use in feeding children. The moist conditioning and milling technique followed for cereals [11] was successfully adapted for decorticating barley in the present study. Moist conditioning renders the husk leathery and also loosens it slightly. This facilitates removal of the seed coat in flaky form and helps to obtain pearled barley.

Popped barley was crispy and possessed a pleasant aroma. Since popping is a dry heat method, it is an energy-saving way to prepare ready-to-eat barley food. The high dietary bulk of popped food could be reduced by using a small quantity of cereal malts [16]. Decorticated chickpea splits and popped chickpea are readily available in local markets of Ethiopia and India. Therefore, it is important to promote popped barley along with popped chickpea or another suitable protein source for preparing nutritious food at the household or community level.

Means of the same column followed by different letters differ significantly according to Duncan's new multiple test (p < .05).

Our results suggest that the weaning foods based on barley and chickpea are nutritionally balanced and possess good growth-promoting quality. The traditional technologies, such as malting and popping of cereals and legumes, could be easily adapted to prepare weaning and supplementary foods from barley and chickpea. The high-protein barley, which is not favoured by the brewing industry, could be diverted for weaning foods. Popped barley has a high potential for developing low-cost weaning and supplementary foods.

Acknowledgements

We thank the United Nations University for the fellowship to A.W. under which this research work was carried out. We thank Mr. B. S. Ramesh for assistance in statistical analysis of the data and Dr. Zewdie WoldeGebriel, director of the Ethiopian Nutrition Institute, for his valuable advice and constructive suggestions during the preparation of the manuscript.

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