Contents - Previous - Next
This is the old United Nations University website. Visit the new site at http://unu.edu
A comparative acceptability and tolerance study of two blended foods in Haiti
R. E. Hayes
Department of Food Science and Nutrition, Olivet Nazarene College, Kankakee, Illinois. USA
Carolyn P. Hannay
Grace Children's Hospital, International Child Care, Port-au-Prince, Haiti
J. I. Wadsworth
Department of Food and Feed Engineering, Southern Regional Research Center, US Department of Agriculture, New Orleans, Louisiana, USA
J. J. Spadaro
Food Products Research Engineering and Development Laboratory, Southern Regional Center, US Department of Agriculture, New Orleans, Louisiana, USA
Corn-based foods now used in US food aid programmes include combinations of processed corn with varying amounts of soy flour, non-fat dry milk, soybean oil, vitamins, and minerals (1). The feasibility of also using cottonseed flour as an ingredient in US Government food blends has been of interest in recent years.
In a previous study, a corn-glandless blend (CC in unsweetened form) emerged as the most promising of a series of nine experimental corn-based food blends 12), each computer-formulated to obtain a maximum chemical score (3, 4), and compared with the two standard PL 480(US Food-for-Peace Program) blends, corn-soy (5) and corn-soy-milk (CSM) (6). All of the blends contained corn meal, oilseed flour(s), and fortifying mixtures of vitamins and minerals. The oilseed flours used were peanut (types from two processes), soy, glandless cottonseed, and a mixture of soy and glandless cottonseed. Some of the blends contained a dairy product, either nonfat dry milk or whey protein concentrate. Some contained lysine monohydrochloride. The 11 blends were evaluated for in vitro and in vivo protein quality, particle size, consistency as a gruel, and storage behaviour. Storage behaviour of the blends, with and without anti-oxidants, was evaluated with respect to colour, flavour, microbial levels, and chemical stability indices (2). CC (unsweetened) showed the highest PER value of the 11 blends. The overall flavour quality and off-flavour scores were very comparable to those of CSM, even under the most severe storage conditions. CC (unsweetened) exhibited better colour stability with increasing temperatures and storage interval than did CSM, with its more labile milk component. CC (unsweetened) showed higher free fatty acid values at room temperature storage. However, flavour scores were not affected.
Glandless cottonseed flour from a succession of glandless varieties has been tested on human subjects, for example, at Texas Women's University (7-9), and in rehabilitation of malnourished children in Peru (10, 11). Glandless cottonseed is being used to produce a high-protein wheat bread currently being marketed in Texas, USA ( 12).
This present study describes a comparative acceptability and tolerance test (13) of two corn-based formulated foods. It was conducted in Haiti, mainly among preschool age children. Modified corn-soy-milk (MCSM), a sweetened version of the leading US Food-for-Peace Program blended food, was matched against a sweetened experimental blend, corn-glandless cottonseed fortified with lysine monohydrochloride (CC).
Haiti was chosen as the site for the present comparative field test of the corn-based blends because corn is a major grain staple in that country (14) and because of the availability of nutrition centres that serve mothers with young children. These centres provide locations for nutritional instruction, immunizations, and monitoring of nutritional status, using a weight-for-age chart (15). Supplementary foods, such as those distributed under PL 480, are also often distributed at the centres.
Bland Formulation, Preparation and Packaging
Formulation. Nutritional criteria used to prescribe blend compositions and test quantities were derived from several sources. PAG guideline number 7 (13) specifies that 50 per cent of the FAO/WHO recommended safe level of protein should be included in the supplement. For a four to six-year-old child, this amounts to 13 grams of protein with the relatively high chemical score of 80 (16). PAG guideline number 8, on protein-rich mixtures for use as weaning foods (17), requires that 100 grams (dry weight) of supplement be provided per day, having, on a dry weight basis, a protein content of at least 20 per cent. With respect to protein quality, the protein efficiency ratio (PER) is required to be not less than 2.1 and preferably greater than 2.3. Some of the other recommendations of PAG guideline 8 are (dry weight basis): for fat, as much as feasible (to increase caloric density) up to 10 per cent; for crude fiber, not more than 5 per cent; for moisture, preferably 5 to 10 per cent; for total ash, not more than 5 per cent; and fortification with vitamins and minerals.
The general USDA guidelines for gruel-type foods (18, 19) and the commodity specifications for corn-based blends (5, 6) were also used in constructing specifications for the CC blend. Some of the salient criteria of these USDA documents are: an average protein content of 20 per cent with a PER, >2.1; fat content, >6.6 per cent; mineral premix, 2.7 per cent; and vitamin premix, 0.1 per cent.
Prior experience in field-testing blended foods had shown that addition of sugar improved acceptability; an 8 per cent level was chosen for both MCSM and CC (20-22).
Amino acid analyses were conducted on the protein-containing blend constituents. Proximate analyses were conducted to the extent needed on all the blend constituents (e.g., on the mineral premix only moisture and ash assays were performed).
Utilizing the proximate analyses and amino acid data, the blend composition of CC was optimized by computer (4) to obtain the best chemical score consistent with certain requirements, derived as described above. The blend (CC) was constrained to contain 20 per cent protein, 6.6 per cent fat, 2.7 per cent mineral premix (6); 0.1 per cent vitamin premix (6) and 8 per cent sugar. Addition of sugar required a different formulation of MCSM from the proportions stipulated by the commodity specification (6). To maintain protein level and caloric density, the blend was computer-formulated with constraints of 20 per cent protein and 6.6 per cent fat. Additional constraints maintained the level of non-fat dry milk at 15 per cent, mineral premix at 2.7 per cent, and vitamin premix at 0.1 per cent. Cornmeal, defatted soy flour, and soy oil proportions were then adjusted by the computer to meet these constraints. The vitamin premix provided the antioxidants B.H.A. and B.H.T., each at a level of 0.0022 per cent (6) in both blends.
Blend preparation end packaging. The ingredients of each blend were thoroughly mixed in a large ribbon blender. The entire food preparation and packaging operation was carried out in a sanitary manner, with workers using hats, masks covering mouth and nose, and rubber gloves. A quantity of each blend was appropriately subpackaged for the various physical, chemical, animal, and microbiological tests. Sterilized jars were used for collection of microbiological samples.
Most of the CC and MCSM was packaged in 0.8 kilogram quantities (approximately 100 grams, dry weight, of supplement per day for one week). Each 0.8 kilogram batch was weighed into a 3.8 litre (four ouart) polyethylene freezer bag, closed with a tie tape, and this bag in turn was placed within a 1.9 litre (half-gallon) rigid cylindrical polyethylene container, then closed with a lid that was sealed with plastic tape. A 53 cc plastic measuring cup, for use in preparing gruel, was included with the food. Numbers were assigned to the CC and MCSM samples on a random basis. There were four 0.8 kilogram packages prepared for each number, one for distribution to each child's mother weekly for four weeks. The plastic containers were packed for shipment in fibreboard drums and held at-18°C until food safety clearances of the US and Haitian governments were obtained on blend tests. This took approximately nine months.
The same analytical procedures described below for blends were also used on blend ingredients for: amino acids, lipids, crude fibre, nitrogen, ash, free fatty acids (vegetable oils), free and total gossypol (cottonseed flour) and levels of microorganisms. With regard to other ingredient analyses, Association of Official Analytical Chemists (AOAC) procedures (23) were used for peroxides (vegetable oils), total arsenic (cottonseed flour), and aflatoxin by minicolumn (corn meal and cottonseed flour); the American Oil Chemists' Society (AOCS) procedure (24) was used for moisture; and residual n-hexane (cottonseed flour) was measured by gas chromatography (25).
Chemical, Biological, and Physical Tests on Blends
Chemical tests. Chemical evaluations on the freshly prepared blends included proximate analyses, amino acids, free fatty acids, peroxide value, available lysine, and gossypol. Of the proximate analyses, nitrogen, fat, and crude fibre were measured by AOCS methods (24), and moisture and ash by AOAC methods (23). Amino acid analyses were performed by gas-liquid chromatography (26) except for tryptophan, which was analyzed colourimetrically (27). Free fatty acids and peroxide value were determined by AOCS procedures (24). Available lysine was measured by the 1-fluoro-2,4-dinitrobenzene method of Couch (28). Blend CC was analyzed for free gossypol by the AOCS method (24) and for total gossypol by the method of Pons and Hoffpauir (29).
Biological tests. Biological tests included animal evaluation of protein quality and microbiological assessment of food safety and spoilage potential. Aflatoxin determination, although strictly chemical, is included with the microbiological group because it originates from a mold.
The AOAC animal assay for protein efficiency ratio (PER) (23) was modified in several respects. The diets were calculated on a 10 per cent protein level rather than on an isonitrogenous basis. This was done because the nitrogen factors of various blend components varied appreciably from the 6.25 nitrogen factor assumed in the AOAC procedure. A composite nitrogen factor for each blend was calculated from analytical results by dividing the total amino acid content by the nitrogen content. In this manner, the composite nitrogen factors were determined to be 6.28 for MCSM and 5.91 for CC. Another deviation from the AOAC PER procedure was that five animals rather than ten were used. The testing laboratory performing the assays has been routinely using five animals for some time for this test and has found only a small difference in the standard error between results for five versus ten animals. The conventional nitrogen factor of 6.25, as specified in the AOAC procedure, was used for computing the Animal Nutrition Research Council (ANRC) casein level.
In the net protein ratio (NPR) calculation (30), 15-day growth and protein intake data of animals on the PER diets were used. Nitrogen digestibility (per cent of nitrogen intake is absorbed) was determined on each animal on pooled data from the 8th through the 15th day of the PER test.
AOAC procedures (23) were used for microbiological assessment of total plate count, total coliforms, faecal coliforms (E. coli), thermophilic plate count, coagulase-positive staphylococci, faecal streptococci, yeasts, moulds, Salmonella and Clostridium perfringens. AOAC procedures (23) were also used for the general aflatoxin (type B1, B2, G1, G2) measurement in the two blends. The nonfat dry milk component of blend MCSM was analyzed separately for type Ml aflatoxin by the method of Stubblefield (31).
Physical and physico-chemical tests. Tests in this category include sieve analysis, reflectance colour, and consistency as a gruel.
American Society for Testing and Materials (ASTM) procedure (32) was followed for sieve analyses of the blends. Samples were split with a Jones-type sample splitter. A mechanical sieve shaker with tapper ("Ro-Tap" testing sieve shaker-W. S. Tyler Company*) was used in the analyses with US standard sieves. Optimum sample weight and shaking time were found in a previous study (2) to be 50 grams and 15 minutes, respectively. Determination of reflectance colour L, a, and b values was done on 10 grams of blend using a Hunterlab digital colour difference meter, model D252A.
The directions for measurement of the cooked gruel consistency, using the Bostwick consistometer, were a modification of those in the corn-soy-milk specification (6). The proportion of dry blend (one heaping 53 cc plastic portion cup) to water (five level portion cups) used in the modification was the same as specified in the directions for preparing the gruel during the field trial. Except for the different proportions of blend to water and omission of evaporated water replacement, the corn-soy-milk specification procedure (6) was followed. Evaporated water would not be replaced in actual gruel preparation during the field trial. Therefore, this step was not included. Because of the expected poorer precision in duplicate determinations, a range of values is reported on five replicate determinations.
Field Test Protocol
Preliminary procedures. Approval was required from both the Haitian and American Governments before conducting the field trial. Background information on test methodology, nutritional characteristics, and food safety analytical values were required by both governments before sending the blended foods to Haiti. In the Haitian Government, approval was required by the Ministry of Health and by its Bureau of Nutrition, William Fougère, M.D., Director. Approval of the US Government was given through the US Department of Agriculture's Human Studies Review Committee. The test samples of blended food were shipped into Haiti via Church World Service' which regularly ships PL 480 food to that country.
Testing criteria. Procedural criteria used in the field test are embodied in PAG guideline number 7 for human testing of supplementary food mixtures (13). Nutritional criteria for prescribing the blend compositions and quantities used have been described above in the formulation section.
PAG guideline 7 requires that human testing be preceded by compositional and nutritional studies of the mixture being considered, assessment of food safety aspects and economic feasibility evaluation. Economic feasibility was not an important factor in this case, since the investigators were interested in a future potential use of glandless cottonseed, which at present is not economically competitive with soy. Compositional, nutritional, and food safety studies were previously conducted, as described in the introduction above (2). The same types of evaluations were performed on the foods actually sent to Haiti. The Haitian field trial concerns one of the four categories of human evaluations outlined by PAG guideline number 7: acceptability and tolerance tests. Some of the features of these tests are that: at least some of the testing should take place in the country for which the protein-rich food is intended; children in both the test and control should be similar size groups; use with the age categories for which the product is intended; knowledge that the mother's acceptability response may influence the child's response; awareness that disease processes tend to influence acceptability and tolerance; use of at least 20 individuals in the test; and a food trial period of at least four weeks. Refusal of the child to eat the food is considered an indicator of poor palatability. Intolerance is judged by noting persistent gastrointestinal upsets. It is also suggested that other clinical responses, such as allergic reactions, be recorded.
Consideration of the provisions of PAG guideline number 7 determined field test procedure, described below, and composition of the questionnaire (figure 1). The questionnaire actually used was a Creole translation of the one shown On the questionnaire, item A concerns the child's acceptability response and items B and C the mother's acceptability response to the food; the factors under item D involve the mother's estimate of the child's gastrointestinal reaction; item E lists other foods eaten during the feeding trial that could have influenced the responses.
Nutrition centre activities. The blended foods were distributed to mothers at five nutrition centres in the Port-au-Prince area of Haiti. One of the co-authors, Carolyn P. Hannay, R.N., nutritionist, supervised food distribution and collection of data
Mothers had from one to four children participating in the field test. The mothers were grouped according to the number of children in the study. A randomization procedure was used to determine whether mothers with one child in the trial would receive an MCSM number or a CC number. Likewise, the randomization procedure was used for sample assignment to mothers with two children in the study, and then for mothers with three children, et cetera. For each mother designated to receive a given blend (e.g., MCSM), each child in her family in the test received different sample numbers of the same blend. Different blends were not assigned to the same mother.
Mothers were given a demonstration on how to prepare gruel from a dry blend. Written directions in Creole were made available for use by nutrition workers. These instructions indicated that one heaping measure of dry blend was to be gradually stirred into five of water and brought to a boil, The boiling mixture was to be stirred for two additional minutes, removed from the heat, cooled to an acceptable temperature for the child, and served. The feeding was to be done three times per day. Some flexibility was allowed the mother in preparation The same reconstitution directions were given to mothers with either MCSM or CC, although it was known that consistencies of the two blends differed. No clue was given that there were two different blends.
The experiment was double-blind. The auxiliary nutritionist distributing the 1.9- litre containers to the mothers did not know which blend a certain number represented. She only knew that a given mother received a sample with a particular assigned number for a certain child. Nor, of course, was the mother told that the blended food she received was of any particular type. The 0.8 kilogram quantities of dry blend, of the same sample number, were provided weekly for four weeks to each child. At the end of the four weeks, the nutrition worker at each clinic, using the Creole translation of the questionnaire in figure 1, recorded the response of each mother and that of her child to the assigned blended food sample. The auxiliary nutritionist also recorded other foods consumed during the test interval, because the blended foods were meant to supplement the regular diet.
For each of the 11 possible responses for preference or gastrointestinal effect, as shown in the questionnaire (figure 1), value numbers were assigned to the different descriptive responses. These assignments are shown in the questionnaire response table (see table 4). Also, for the purpose of statistical analysis, the nutrition centre at Christi-Roi (69 children) was designated: no. 1; at Carrefour Feuilles (34 children): no. 2; and the combined Delmas, Pernier, and Salvation Army centres (54 children): no 3.
Several approaches were taken to handling the data by analysis of variance (A NOVA) (33). In some cases, data from all participating children were used in the analysis. In other instances a hierarchal design was employed that used only part of the collected data.
Combining the data from all the clinics, ANOVA was used to test the 11 questionnaire responses for statistical significance among the variations of the nutrition centres (three), blend types (two), and whether a difference between blends depends upon the nutrition centre (interaction effect). The same variations were examined statistically using only the first child in each family. The rationale for this variation was that perhaps data from different children of the same family are correlated, because the same mother responds to all the questions.
Several circumstances developed during the field test that necessitated repeating the ANOVA after certain data were omitted. For a series of samples, more than one child used the same sample number. This problem is understandable in a setting with a high incidence of protein-caloric malnutrition (14). There were also a few children in the study who were above the originally set upper age limit of five years.
BLENDED FOOD QUESTIONNAIRE
Questions to be asked of each mother for each child by the nutrition clinic worker after the four week feeding trial
Child's first name___________________________
Age:_________How many children of this family are participating in this feeding study? Blended food sample number:____________
A. How did your child like the blended food as indicated by eargerness to eat the food?
B. How did you like the blended food?
Good? Fair? Poor?
Ease of preparation_____________________
D. During the four weeks the new food was eaten, did:
Increase? Decrease? Ream in the same
stool contents _____________
E. What other foods did your child consume during the four weeks the food supplement was eaten?
TABLE 1. Microbiological Analyses1 on Blend Ingredients and on Blends
|Ingredient or Blend||Total Plate count org/g||Total Coliforms MPN/g||Thermophilic Plate Count org/g||Moulds org/g||Aflatoxin (types B1+B2+G1+G2) ppb||Miscellaneous|
|Cornmeal, processed gelatinized||100||*2||250||< 10||< 5|
|Soy flour, deffated, toasted||1,000||23.0||550||<10||- 3|
|Cottonseed flour, glandless, defatted||64,000||240.0||4,000||50||< 5|
|Milk, nonfat, dry||800||*||350||<10||-5|
|Sucrose granulated||< 100||*||<100||<10||-||Listed4 below|
|Vitamin premix with antioxidant||<100||*||<100||<10||-|
|Soy oil, refined,|
|bleached, stabilized||<100||*||< 10||<10||-|
|Cottonseed oil, refined,|
|bleached, deodorized||< 100||*||< 10||< 10||-|
1. Association of Official Analytical Chemists (26) except for
the nonfat dry milk component of blend MCSM (see footnote 3,
below), for which the method of Stubblefield (31 was used.)
2. * = not found in 1110 g portion tested.
3. Dashes indicate that the analysis was not performed on the indicated commodity.
4. Uniform results were obtained on all ingredients and blends cited above for each of the following tests: Faecal coliforms (E. coli) not found in 1/10 g portion tested. Faecal streptococci: <10 org/g. Coagulase positive staphylococci: not found in 1/10 g portion tested. Clostridium perfringens: <10 org/g. Salmonella: negative. Yeasts: <10 org/g.
5. < 20 value for blend MCSM is for aflatoxin types B1+ B2+G1+G2. A separate determination on the nonfat dry milk component of this blend indicated that the aflatoxin M1 level was < 0.5 ppb.
ANOVA's were made, excluding observations on children sharing the same numbered sample, and again excluding observations on children over five years, and finally excluding both sets of observations. In making these reruns, appropriate adjustments had to be made in some retained data because of changes in child-order within family and total number of children in the family participating in the study,
RESULTS AND DISCUSSION
Quality of Blend Ingredients
With respect to oil stability, the free fatty acid content (as per cent oleic in total lipids) was 0.03 per cent for cottonseed oil and 0.04 per cent for soy oil; the peroxide value (meq/kg lipids) was 6.0 for cottonseed oil and 14.0 for soy oil. The peroxide values were somewhat high, especially for soy oil, for expectation of a long shelf-life. However, an acceptability problem did not develop with either blend.
With regard to levels of toxic chemicals in the glandless cottonseed flour (a non-commercial product), the residual hexane level was 51.2 ppm; total arsenic was <0.1 ppm; the free gossypol content was 504 ppm, and the total gossypol was 960 ppm. The residual hexane level fell below a maximum of 60 and the total arsenic level was lower than the 0.2 limit proposed in the 1980 United Nations University guideline for cottonseed flours (34). The free and total gossypol contents were beneath the maximum levels of 600 ppm and 12,000 ppm, respectively, specified by PAG guideline number 4 (35), which was the most recent available at the time the blends were prepared. The glandless flour used in this study, however, exceeded the more stringent maximum of 450 ppm for free gossypol, but was within the total gossypol maximum of 3,000 ppm proposed by the 1980 cottonseed guideline (34).
The results of microbiological tests on blend ingredients are shown in table 1. There are several standards available against which the sanitary quality of at least some of the ingredients can be compared. PAG guideline 11 for the sanitary production and use of dry protein food (36) outlines acceptance criteria for certain ingredients to be used in dried blends of the type described in the study. The Protein Advisory Group guidelines sampling plan for microbiological tests was established for ascertaining microbial levels in factory shipments and involves taking multiple samples. In the present study, however, duplicate assays (AOAC procedure) of a single sample were used. The AOAC assay averages were used to determine whether there was reasonable, but not exact, conformance to the PAG criteria. The PAG "m" level represents the number of organisms below which no basis for concern exists. In all cases in which an ingredient in table 1 is covered by PAG guideline 11, the actual number of organisms meets the "m" level requirement. Thus, cornmeal, soy flour, and cottonseed flour each have a lower plate count than 100,000. Nonfat dry milk has a lower total plate count than 50,000 and has lower than detectable levels of faecal coliforms and coagulase-positive staphylococci. Soy flour, cottonseed flour, and nonfat dry milk all meet the negative Salmonella requirement for these commodities.
Comparison with the 1980 guideline for edible cottonseed flours (34) showed that the cottonseed sample of table 1 met the specifications for E. coli, staphylococci, Salmonella, and yeasts and mounds, but the guideline's negative coliform and 50,000/9 total plate count requirements were exceeded. However, faecal coliforms could not be detected in the cottonseed sample. Soy flour (table 1 ) had a lower total plate count than the maximum of 50,000 indicated by the CSM especification (6) and by the 1980 United Nations University guideline for production of edible, heat-processed soy grits and flours (37). The soy flour sample also met the requirements of the latter document with respect to E. coli, Salmonella, Clostridium perfringens, and coagulase-positive staphylococci.
Although available microbial standards differ somewhat in their requirements, it is considered that the ingredients listed in table 1 were of generally satisfactory microbiological quality with regard to these criteria.
Characteristics of Actual Field Test Blends
After preparation for shipment, the two blends (CC and MCSM) were evaluated with respect to three categories of characteristics: food safety and poilage potential; nutritional; and physical and physico-chemical.
Food safety and spoilage is reflected in the blend microbiological results of table 1 and in the chemical test results in table 3. Both blends met the full microbiological criteria of the CSM specification (6). This document includes specifications for aerobic plate count, Salmonella, E. coli, coagulase-positive staphylococci, and aflatoxin. In the section above on quality of blend ingredients, it has been explained why approximate rather than exact conformance to PAG guideline 11 (36) can be determined from the microbiological results. Th "m" level of the PAG sampling plan represents the level below which no basis for concern exists; the "M" level represents the level that, if exceeded by any especimen within a sample, is cause for rejection of the whole lot. The negative coagulase-positive staphylococci, faecal coliform, and Salmonella findings for both blends and the aerobic plate count for blend MCSM all met the respective "m" level criteria. The aerobic plate count of 31,000 for blend CC exceeded the "m" level of 10,000/9 but fell below the "M" level of 200,000/9. It is therefore considered that the microbiological quality of the blends reasonably meets the requirements of PAG guideline 11. Table 1 also lists counts for other categories of organisms sometimes used to indicate food safety or quality: total coliforms, faecal streptococci, thermophiles, yeasts, moulds, and Clostridium perfringens. Of these, neither faecal streptococci, Clostridium perfringens, yeasts nor moulds were found in the blends. Both total coliform (especially with negative E. coli findings) and thermophile levels were adequately low for products of this type (38).
Chemical indices of toxicity and food quality stability are given in table 3. The free (92 ppm) and total (250 ppm) gossypol levels of blend CC are considerably below the levels of 450 ppm and 3,000 ppm, respectively, of the 1980 United Nations University guideline for edible protein flours and related products (34). The expected level of free gossypol in this blend, based upon the content in the cottonseed flour component, was 170 ppm rather than the actual 92 ppm. This reduction of free gossypol during blending was probably caused by combination with lysine and ferrous fumerate. The peroxide values for both blends are considered to be well within an acceptable range for products of this kind 12). The free fatty acid value for blend CC is considerably higher than that for blend MCSM. An earlier study by Hayes et al. (2) showed that blends containing cottonseed flour tended to have higher free fatty acid values, although this did not appear to result in significantly poorer off-flavour scores for such blends. Table 3 also shows that blends CC and MCSM both had similar high available lysine values. Thus, overall, the chemical stability parameter indicated good quality for both blends immediately after preparation. As related above, the blended food was kept at-18°C until shipment to Haiti in order to retard deterioration.
Nutritional comparison of blends CC and MCSM is summarized in table 2. The proximate analyses, chemical scores, PERs, NPRs, nitrogen digestibilities and caloric densities of the two blends are very similar, despite some marked differences in ingredient composition. Although there are some minor deviations, the nutritional characteristics of both blends closely approximate the USDA criteria levels previously listed.
TABLE 2. Composition, Protein Quality and Caloric Density of Field-Tested Food Blends
|Category||Factor||Blend CC||Blend MCSM|
|Cornmeal, processed, gelatinized (%)||52.5||45.4|
|Soy flour, defatted, toasted (%)||-||22.9|
|Cottonseed flour, glandless, defatted (%)||31.5||-|
|Milk, nonfat, dry (%)||-||15.0|
|Sucrose, granulated (%)||8.0||8.0|
|Soil oil (%)||-||5.9|
|Cottonseed oil (%)||5.1||-|
|Vitamin premix1 with antioxidants (%)||0.1||0.1|
|L-Lysine HCI (%)||0.1 (0 09)||-|
|Crude fibre (by)||0.9||1.0|
|Carbohydrate by difference (%)||58.6||57.6|
|Protein quality||Chemical score2||80||84|
|Limiting amino acid(s)||threonine||methionine + cystine|
|PER (adjusted)3 ± S.E.||2.124 ± 0.05||2.264 ± 0.06|
|NPR±S.E.||3.625 ± 0.07||3.725 ± 0.05|
|Nitrogen digestibility (%)||87.7||85.6|
|Caloric density||Kcal/100g (calculated)||374||372|
1. The compositions of the mineral premix and vitamin premix
with antioxidants are given in reference 3.
2. The chemical score is the amino acid score of the most limiting essential amino acid. The amino acid scores were computed according to the definition in reference 16.
3. Actual PER values were proportionally adjusted to an assigned value of 2.50 for ANRC reference protein.
4. The PER values of the two blends were not found to be significantly different
5. The NPR values of the two blends were not found to be significantly different.
Table 3 compares the two field test blends with regard to cooked gruel consistency, sieve analysis, and reflectance colour. Using the same ratio of dry blend to water for both blends, the CC blend had a notably thicker consistency. The sieve analysis patterns of the two blends were similar. Blend CC had a slight green cast (negative Hunter b value) due to its cottonseed flour component. As described below, the field study results showed that the consistency difference significantly affected comparative acceptability of the two blends but that the colour difference did not. Gruel consistency can be changed easily by modifying the ratio of dry blend to water.
Contents - Previous - Next