Conclusions

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Conclusions

The computer formulation can be an effective tool for comparatively evaluating the potential of a re gion's market commodities to meet the protein-energy needs of small children at the lowest cost. The approach is illustrated by results pertinent to the Lusaka area in Zambia that list a variety of home-prepared and commercially processed weaning formulations with accompanying calculated nutritional and cost values. We believe that the methodology is applicable throughout the developing world.

TABLE 7. Texture/softness and appearance of cooked product for oilseeds, non-oilseed legumes, and other potential home-prepared blend ingredients

Commodity	Pretest treatment^a	Description of texture/softness^bappearance of cooked (2 min) product
Soya beans	10-min roast, dehulled	Gritty and very watery, uncooked appearance; yellow colour
	15-min roast, dehulled	Grits soft; watery; brown colour
	20-min roast, dehulled	Particles visible but soft; watery
	25-min roast, dehulled	Particles visible but soft; watery
Sunflower seeds	10-min roast, dehulled	Smooth with some hard particles
Sunflower seeds	15-min roast, dehulled	Smooth: very minute hard particles
Groundnuts^c	15-min roast	Particles visible but soft; light colour
Groundnuts^c	20-min roast	Sample overroasted, turned black
Red beans (Phaseolus)	15-min roast, dehulled	Thick, smooth porridge; very soft particles
Red beans (Phaseolus)	20-min roast, dehulled	Thick, very smooth porridge
Cowpeas	15-min roast, dehulled	Thick gelatinous porridge; very soft
Cowpeas	20-min roast, dehulled	Thick gelatinous porridge; very smooth
Bambara nuts	15-min roast, dehulled	Very smooth porridge; no gritty particles
Bambara nuts	20-min roast, dehulled	Very smooth porridge; no gritty particles
Caterpillars, dried	None	Quite soft, but not very cooked
Pumpkin leaves, dried	None	Quite soft, but probably not soft enough
Pumpkin leaves, dried	Presoaked for 1 min	Soft
Yeast, dried	None	Very soft

a. The roasting and dehulling processes are described in the text
b. The text describes the glass slide technique used after a two-minute cook for estimating softness.
c. Roasted groundnuts are included for comparison with other oilseeds Most frequently, unroasted ground-nuts are pounded and introduced into porridge The unroasted groundnuts with skins were selected as a potential home-prepared weaning blend ingredient.

The high tryptophan level in the human milk protein quality reference pattern [33] strongly influences the commodities selected by the computer for the home-prepared blends, and makes it necessary to add purified tryptophan to commercially processed blends to reach acceptable protein quality. Only a few of the market-available foodstuffs examined (two forms of cow's milk, two kinds of dried leaves, eggs) have especially high tryptophan content. Further search for other high-level tryptophan contributors among Zambian foodstuffs would therefore be desire able. The use of the amino acid pattern for children age two to five years, with its much lower tryptophan level, would considerably reduce this constraint.

The use of home-prepared or commercially processed blends with higher protein quality than necessary at increased cost cannot really be justified unless organoleptic acceptability is markedly enhanced. For commercially processed blends, it was not possible to meet the minimum protein requirement without adding one or more amino acids. When purified amino acids are available, their use is certainly economically indicated. For mixtures selected from all available ingredients, this addition actually results in a lower-cost blend (a decrease as great as 7.6%) than if a purified amino acid were not used.

The procedure described can be used to invest)gate quickly the effect of seemingly desirable modifications on types and proportions of ingredients, likely organoleptic acceptability, calculated nutritional values, and cost. Examples of possible beneficial change from the optimum formulation are increase or decrease in an ingredient to enhance organoleptic acceptability or reduce the possibilities of gastrointestinal problems; elimination of one of two similar commodities or substitution of one component with a similar type to accommodate what may be available in the home or in a local market; and elimination of a small quantity of an ingredient called for in a given formulation to simplify commodity handling.

TABLE 8. Home-prepared formulations and calculated parameters, limiting selection to mother-favoured ingredients (fat-sugar energy blends)

Commodities and calculated parameters	Blend formulation constraints(least-cost mixtures at indicated absorbed amino acid scores^a)
	Jan		Feb		Mar-Oct		Nov-Dec
	A	B^b	A	B^b	A	B^b	A	B^b
	>=65	=	>= 65	=	>=65	=	>=65
Commodities (as is %) maize meal	35.0	33.8	35.0	16.5	52.0	27.1	35.0	35.0
rice, polished, roasted				14.2		6.1
groundnuts with skins					5.6
pumpkin leaves, dried		6.8
milk, fresh	51.6	49.6	51.6	57.1	22.1	53.9	51.6	51.6
milk, nonfat, dried	9.3	5.6	9.3	8.3	14.4	8.9	9.3	9.3
sugar	4.1	4.2	4.1	3.9	5.9	4.0	4.1	4.1
Proximate analyses (%dry basis)crude protein	1 5.7	16.0	1 5 .7	1 5.5	1 5.9	1 5 .6	1 5.7	1 5.7
fat	7.0	7.0	7.0	7.0	7.0	7.0	7.0	7.0
crude fibre	0.7	1.7	0.7	0.6	0.8	0.6	0.7	0.7
ash	3.1	4.1	3.1	2.8	2.8	3.0	3.1	3.1
moisture	95.0	89.8	95.0	108.1	35.7	100.5	95.0	95.0
CHO by difference	73.6	71.2	73.5	74.1	73.5	73.8	73.5	73.5
Nutritional indexes amino acid score in blend^c	67.3	66.8	67.3	72.4	61.4	69.4	67.3	67.3
absorbed amino acid score^a	70.3	71.0	70.3	74.8	65.0	72.2	70.3	70.3
limiting amino acid	Trp	Trp	Trp	Trp	Trp	Trp	Trp	Trp
absorbed protein content (% d.b.)^d	15.0	15.0	15.0	15.0	15.0	15.0	15.0	15.0
apparent energy content of blend (kcal/100 g d.b.)^d	420.1	411.8	420.1	421.6	420.3	420.7	420.1	420.1
absorbed energy content (kcal/100 g d.b.)^d	420.1	401.5	420.1	421.6	420.3	420.7	420.1	420.1
% total available energy from fat	15.0	15.3	15.0	14.9	15.0	15.0	15.0	15.0
% total available energy from protein	14.3	14.6	14.3	14.2	14.3	14.3	14.3	14.3
cost^e (US$/kg d.b.)^d	1.69	2.36	1.69	2.42	1.54	1.99	1.69	1.69

a. Amino acid score of the mixture of amino acids calculated to be absorbed into the blood. The basic definition of amino acid score, as given in ref. 33, is applied to this absorbed mixture.
b. The amino acid score by absorbed amino acids halfway between the highest obtainable by computer, under the particular conditional constraints, and that of the least-cost blend that still meets minimum guidelines (blend A). The absorbed amino acid score for an A blend may exceed 65 if that blend represents the least-cost mixture having a minimum score of 65 In one instance, because of restricted commodity availability, the absorbed amino acid scores for the A and B blends are identical.
c. Amino acid score of the blended food mixture as defined in ref. 33.
d. d.b. =calculation on a dry weight basis.
e. The cost of home-prepared blends is that estimated for the various blend ingredients during March to June 1989 in the form in which they are mixed together to constitute the weaning food. Some ingredients are used as purchased; others are home-processed, and appropriate modification of the original market cost must be made (table 3). The exchange rate for June 1989 was 12 Zambian kwacha (K) per United States dollar (US$).

TABLE 9. Home-prepared formulations and calculated values, examples of alternative formulations with similar type components

Commodities and calculated parameters	Milk component alterations(April-October formulations) Selection from all available components: fat-sugar energy blends; intermediate^a absorbed amino acid score			Dried leaf component alterations (January formulations) Selections limited to mother-favoured components: high energy from fat blends; intermediate absorbed amino acid score
Commodities and calculated parameters	Fresh milk excluded	Original least-Cost mixture	Non-fat dry milk excluded	Original least-cost mixture	Pumpkin leaves excluded
Commodities (as is %)maize meal		0.4		27.6	28.2
rice, polished, roasted	20.1	5.5	16.1
sorghum, dehulled, roasted	43.3	31.0	19.3
pumpkin leaves, dried				3.0
cowpea leaves, dried			6.9		2.3
kapenta, dried			1.5
milk, fresh		51.2	52.0	68.0	67.9
milk, non-fat, dried	24.4	7.7		1.4	1.6
oil, cooking	4.8
sugar	7.4	4.2	4.2
Proximate analyses (% dry basis)crude protein	16.0	16.2	16.3	15.9	15.9
fat	7.0	7.0	7.0	11.0	11.0
crude fibre	0.6	0.7	1.9	1.3	1.3
ash	2.4	2.4	2.9	3.7	3.3
moisture	8.0	92.1	92.0	160.3	1 59.7
CHO by difference	74.0	73.7	71.9	68.1	68.5
Nutritional indexes
amino acid score in blench	67.8	67.0	65.8	66.7	66.5
absorbed amino acid scores	72.2	72.2	71.6	70.7	70.4
limiting amino acids	Trp	Met+Cy, Trp	Lys, Trp. Met + Cys	Trp	Trp
absorbed protein content (% d.b.)^d	15.0	15.0	15.0	15.0	15.0
apparent energy content (kcal/100 g d.b.)^d	423.0	422.8	415.8	434.8	436.5
absorbed energy content (kcal,/100 g d.b.)^d	423.0	422.8	405.4	423.9	425.6
% total available energy from fat	14.9	14.9	15.1	22.8	22.6
% total available energy from protein	14.2	14.2	14.4	13.8	13.8
cost^c (US$ kg d.b.)^d	2.17	1.83	3.15	2.04	1.94^f

a. The amino acid score by absorbed amino acids halfway between the highest attainable by computer, under the particular conditional constraints, and that of the least-cost blend that still meets minimum guidelines (>65).
b. Amino acid score of the blended food mixture as defined in ref. 33.
c. Amino acid score of the mixture of amino acids calculated to be absorbed into the blood. The basic definition of amino acid score, as given in ref. 33, is applied to this absorbed mixture.
d. d.b. = calculation on a dry weight basis.
e. The cost of home-prepared blends is that estimated for the various blend ingredients during March to June 1989 in the form in which they are mixed together to constitute the weaning found. Some ingredients are used as purchased; other ingredients are home-processed,and appropriate modification of the original market cost must be made (table 3). The exchange rate for June 1989 was 12 Zambian kwacha (K) per United States dollar (US$).
f. The cost of the blend that uses cowpea leaves is actually a bit lower than the original optimized mixture containing pumpkin leaves. This is because the intermediate amino acid score, as defined in footnote a, is a hit lower for the mixture containing cowpea leaves.

TABLE 10. Commercially processed formulations and calculated parameters, limiting selection to mother-favoured ingredients (home addition of let and sugar)

Commodities and calculated parameters quality)	Blend formulation constraints
	No added chemicals	Added amino acid(s) only		Added amino acid(s) + vitamin-antioxidant-ineral mixture
	No cost constraint	Least-cost mixtures at indicated absorbed amino acid scores^a
	Max. absorbed amino acid score^a (below standard protein	B^b A+1/3 A>= 65	B^b = A+1/3 (max - A)	A>= 65	Bb=A+1/3 (max - A)
Commodities (as is %)maize meal	12.58				1.96
maize whole grain	29.49	43.08	43.39	38.17	36.37
Beans (Phaseolw), dehulled 43.09	42.24	41.85	43.94	43.68
Groundnuts shelled, deskinned	6.54	6.34	6.34	6.69	6.71
L-methionine		0.04	0.10	0.05	0.11
L-tryptophan		0.02	0.05	0.02	0.04
vitamin-antioxidant-mineral mix^c				2.80	2.80
home fat	0.92	0.92	0.92	0.93	0.93
home sugar	7.38	7.36	7 35	7.40	7.40
Proximate analyses(% dry basis)
crude protein 17.6	17.6	17.6	17.6	17.6
Fat	7.0	7.0	7.0	7.0	7.0
crude fibre	1.5	1.6	1.6	1.6	1.6
ash 2.6	2.5	2.5	5.4	5.4
moisture 8.5	8.7	8.7	8.1	8.1
CHO by difference	71.3	71.3	71.3	68.4	68.4
Nutritional indexes
amino acid score in blends^d	55.3		63.3	55.2	63.2
absorbed amino acid score^a	57.2	64.9	74.2	64.9	74.2
limiting amino acids	Met + Cys, Trp	Mel + Cys, Trp	Met + Cys, Trp	Met + Cys, Trp	Met+ Cys, Trp
Absorbed protein content(% d.b.)^e	15.0	15.0	15.0	15.0	15.0
Apparent energy content of blend (kcal/100 g d.b.)^e	418.7	418.4	418.5	407.0	407.1
Absorbed energy content (kcal/100 g d.b.)^e	408.2	408.0	408.0	396.8	396.9
% total available energy from fat	15.1	15.1	15.1	15.5	15.5
% total available energy from protein	14.3	14.3	14.3	14.7	14.7
cost^f (US$/kg d.b.)^e	1.02	1.06	1.12	1.22	1.27

a. Amino acid score of the mixture of amino acids calculated to be absorbed into the blood. The basic definition of amino acid score, as given in ref. 33, is applied to this absorbed mixture.
b. The amino acid score by absorbed amino acids one-third of the way between the highest attainable by computer, under the particular conditional constraints, and that of the least-cost blend that still meets minimum guidelines (blend A).
c. The composition of this vitamin-antioxidant-mineral mixture is defined in ref. 13.
d. Amino acid score of the blended food mixture as defined in ref. 33.
e. d.b. = calculation on a dry weight basis.
f.The cost of commercially processed blends is that estimated for the various blend ingredients as they enter the cooker-extruder. Processing costs, other than those necessary for preparing certain ingredients for the cooker-extruder (table 4), are not included. Product packaging costs are not included.

In comparing both types of formulations, it is apparent that some marked differences exist in ingredients and/or ingredient proportions among the mixtures. Such differences make it imperative that prospective weaning mixtures be screened by Zambian mothers to determine which are acceptable organoleptically [32]. Further screening by children of blends that are unusual mixtures will be necessary to determine organoleptic acceptability and gastrointestinal tolerance [32].

The computer-formulation procedure is designed primarily to meet energy and protein requirements. Homeprepared formulations and commercially processed blends without added vitamin-mineral mix must be supplemented by other indigenous foods to supply these nutrients [5, 37]. The computer programme can identify particular needs by incorporating entry values and requirement levels for the limiting essential nutrients. Further extension of the technique could specify combinations of ingredients that would most closely approximate requirements for protein-energy and also for selected vitamins and minerals likely to be deficient in the diet.

Acknowledgements

The authors wish to particularly thank those individuals associated with the following institutions who have assisted in this project: National Council for Scientific Research, National Food and Nutrition Commission, and Association of University Women in Zambia; and Armour Pharmaceutical Co., RJR Nabisco, Inc., Genetic Engineering Facility of the University of Illinois, Southern Regional Research Center of the US Department of Agriculture, and Olivet Nazarene University in the United States.

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