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Energy-dense weaning foods liquefied by germinated-wheat amylase: Effects on viscosity, osmolality, macronutrients, and bacterial growth

M. A. Wahed, D. Mahalanabis, Mahfuza Begum, M. Rahman, and M. S. Islam

Results

The viscosity measurements confirmed the high degree of efficacy of germinated wheat flour in liquefying thick, sticky porridges. The addition of ARF reduced viscosity by 98% in rice porridge, 97% in khichuri, and 87% in wheat porridge (table 1). The viscosity of the treated porridge was reduced sharply within 10 to 15 minutes, whereas that of the untreated porridges kept increasing over time (see Figure. 1. The viscosity of 20 g% rice porridge over time with and without ARF treatment).

TABLE 1. Effect of 2 g% of ARF on the viscosity of porridges

Values are means ± SD.

1. Approximate relationship of viscosity to the consistency of the porridges: > 10,000 cps, very thick and non-spoonable; 6,000-10,000 cps, thick hut spoonable; 3,000-6,000 cps, easily spoonable; 1,000-3,000 cps, souplike [8].
2. Porridge of 20% rice flour and 6% lentils, with oil and salt.

The osmolality and the glucose content of ARF-treated rice porridge and khichuri were significantly higher than for the untreated porridges (table 2). There was virtually no difference in the caloric and protein contents of the treated and untreated porridges.

TABLE 2. Osmolality and glucose, calorie, and protein content of rice porridge and khichuri with and without ARF

a. The khichuri contains added salt, while the rice porridge does not.

In addition, we found that ARF can be stored for a few months without any change in its capacity to reduce the viscosity of rice porridge (table 3).

TABLE 3. Effect of storage in polyethylene packets under room conditions on the capacity of ARF to reduce the viscosity of 20 g% rice porridge

Bacterial multiplication after the addition of a known inoculum of E. cold LT or S. flexneri was not different in ARF-treated and untreated rice porridges kept at room temperature (see Figure. 2. The multiplication of Shigella flexneri (A) and enterotoxigenic Escherichia cold LT (B) in 20 g% rice porridge with and without ARF treatment).

Discussion

We have added two important new dimensions to the understanding of the properties of porridges liquefied with ARF: the effects on osmolality and on the growth of enteric pathogens under experimental conditions. We also did limited studies on the storage properties of ARF powder. In addition, we have characterized a food likely to be suitable and acceptable to mothers in Bangladesh as an energy-and protein-rich weaning food.

Our aim was to develop a liquefied, energy-dense porridge suitable for use in feeding infants and young children suffering from diarrhoeal and other illnesses, for whom the osmolality of the fluids and foods given is important. The addition of ARF increased the osmolality of the food, although not to a hyper-osmolar level; furthermore, amylase breaks down complex starch into smaller molecules of varying size, and their rapid breakdown in vivo may lead to osmotic problems in the intestinal lumen and increase diarrhoea. Therefore, clinical studies are needed to ascertain the stability of such a diet in infants with diarrhoea.

The contamination of infants' food with pathogenic micro-organisms always raises concern about infectious diarrhoea in children [9, 10]. We therefore evaluated the growth of two important entero-pathogens in porridges liquefied with ARF. It was reassuring to note that these bacteria did not grow any faster than in untreated porridge of the same composition. Reducing pH may make a porridge more resistant to bacterial overgrowth. Thus, further studies of the beneficial effect of changing its pH, together with liquefaction, may be interesting and useful.

We also confirmed earlier findings [11] that the measured reduction of viscosity of rice-based weaning meals was satisfactory, and the measured energy density was, as expected, high. It has been postulated [12] that an energy density of 1 kcal per gram of food can meet the energy needs of an infant young child with three to four meals a day. However, during illnesses such as diarrhoea, the amount taken per meal may be a good deal lower, requiring more frequent feeding.

The limited data on the storage properties of ARF were encouraging. Even after three months of storage the powder looked good, was powdery, and did not cake, nor was there any alteration in its smell or texture or in its ability to liquefy a sticky porridge.

In conclusion, rice-based porridges can conveniently be liquefied by adding germinated wheat flour rich in amylase. Such flour has suitable storage characteristics, and can be produced and distributed at the village level. The osmolality characteristics of this energy-rich porridge make it suitable as a weaning food for infants and small children. On the basis of these findings, a series of clinical trials were initiated to evaluate the food's efficacy in infants and children with acute watery diarrhoea, with dysentery due to shigellosis, and with severe proteinenergy malnutrition recovering from diarrhoea.

Acknowledgements

This research was supported by the Swiss Development Corporation and the International Centre for Diarrhoeal Disease Research, Bangladesh, which is supported by countries and agencies that share its concern for the health problems of developing countries. Current donors include the aid agencies of the governments of Australia, Bangladesh, Belgium, Canada, Denmark, France, Japan, the Netherlands, Norway, Saudi Arabia, Sweden, Switzerland, the United Kingdom, and the United States; international organizations, including the United Nations Development Programme, the United Nations Population Fund, the United Nations Children's Fund, and the World Health Organization; and private foundations, including the Ford Foundation and the Sasakawa Foundation.

We acknowledge the assistance of Dr. J. Albert in the microbiology part of the experiments and the secretarial assistance of Mr. Manzurul Haque.

References

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