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Treatment of sorghum grains with calcium hydroxide for calcium enrichment

Pushpa Bharati and M. P. Vaidehi

Sorghum, the third largest cereal crop in India, is mostly used for human consumption and is an important staple food for a large proportion of the Indian population. It has been found to be low in both the essential amino acid Iysine and in calcium. Studies have shown that the Iysine content of sorghum can be improved by infusion [1], but little effort has been made to improve its calcium content. The present study was undertaken to determine the best method for increasing the calcium content of sorghum grain.

Naturally occurring polyphenols are known to lower the nutritional value and digestibility of sorghum, and soaking the grains in calcium hydroxide (lime) solution helps to remove the tannins [2] to enhance the utilization of nutrients and digestibility [3]. Samples were not analysed for polyphenol content in this study because the storage period lasted for only three or four days and greying was not a problem.

Materials and methods

Four varieties of sorghum grain (SB-1079, DSH-1, CSH-5. and SB-905) were obtained from the Regional Research Station in Dharwad. The grain was cleaned before further processing. All the varieties were treated with 0.2% calcium hydroxide solution in a ratio of 1:3 w/v of grain to solution. Two methods were applied: (1) dipping or soaking in calcium hydroxide solution and air-drying for 24 hours, and (2) dipping or soaking in calcium hydroxide solution, washing with distilled water, and air-drying for 24 hours. These two treatments were carried out on both germinated and ungerminated grain. Untreated sorghum grain served as the control.

There were five soaking periods: dipping only, and soaking for 4, 8, 16, and 32 hours. After drying, the samples were powdered in a dry grinder and stored in a refrigerator for further analysis. The calcium content of the processed sorghum was analysed by precipitating it as calcium oxalate in dilute H2SO4 against the standard KMnO4 [4]. Although soaking adds significant quantities of water, the water is easily and inexpensively removed by sun-drying.

Results and discussion

The calcium content of the four sorghum varieties was analysed before and after processing, and the results are presented below.

Varietal variation

Among the four untreated varieties, CSH-5 showed the maximum calcium content (63.0 mg per 100 g), followed by DSH-1 and SB-905 (table 1). SB-1079 showed the lowest calcium content (32.0 mg per 100 g).

Deosthale and Belvady [5] studied varietal differences in the calcium content of sorghum grains. Their values ranged from 23.2 mg per 100 g for CSV-1 to 43.2 mg per 100 g for CSV-3, which were much below the range observed in the present study. Perhaps these lower values reflected varietal, seasonal, and locational differences in the crops of sorghum harvested.

In our study, germinated grain of all varieties except SB-1079 showed greater increases in calcium content when soaked in lime and dried than ungerminated grain. A maximum calcium content of 253.6 mg per 100 g was obtained in the germinated DSH-1 variety after soaking in lime and drying. Increasing the soaking time from dipping only to four hours resulted in an increased calcium content in SB-1079 and CSH-5, whereas in the DSH-1 and SB-905 varieties the calcium content was increased for up to eight hours of soaking. Regardless of the soaking method or length of soaking, SB-905 showed significantly lower calcium content than the other varieties (table 2). The calcium contents of the SB-1079, DSH-1, and CSH-5 grains were comparable.

TABLE 1. Calcium content of four varieties of sorghum (milligrams per 100 g of grain) after different treatments with 0.2% calcium hydroxide solution






1 2 3 4 Mean 1 2 3 4 Mean



Dipped 78 32 197 79 96.5 76 55 209 107 111.7
4 hrs 277 229 287 194 246.7 215 214 321 173 231.0
8 hrs 266 242 209 187 226.0 298 216 303 197 253.5
16 hrs 214 180 257 238 222.3 235 224 273 171 225.7
32 hrs 313 175 193 170 212.7 227 190 162 149 182.0
Mean 229.6 171.6 228.6 173.6   210.2 179.8 253.6 159.6  






Soaked 73 63 118 82 84.5 76 55 136 69 84.0
4 hrs 210 166 339 244 239.7 193 182 251 204 207.5
8 hrs 220 211 282 198 227.7 211 183 259 214 216.7
16 hrs 236 207 218 187 212.0 226 205 262 160 213.3
32 hrs 309 164 271 224 242.0 234 164 215 184 199.3
Mean 210.0 162.2 245.6 187.0   188.0 157.8 224.6 166.2  

Treatments: 1. Ungcrminated grain dipped or soaked and dried
2. Ungerminated grain dipped or soaked. washed. and dried.
3. Germinated grain dipped or soaked and dried.
4. Germinated grain dipped or soaked. washed. and dried.

Effect of the method of treatment

Irrespective of the variety of grain and the duration of soaking, the germinated grain showed a higher calcium content than the treated ungerminated grain (table 2). Some of the treated grain samples were washed before drying to determine how much calcium adhered to the seed coat, how much had penetrated the endosperm, and how much was lost during washing. The washing resulted in decreased calcium levels; when not washed after soaking, both germinated and ungerminated sorghum grain showed significantly higher calcium contents (238.1 mg and 209.4 mg per 100 g respectively) than the grain that was washed.

The loss of calcium during washing might be attributed to the removal of calcium adhering to the surface of the grain as well as to the osmotic gradient created by the washing process. The percentage of calcium lost was minimal when washing occurred after 4, 8, or 16 hours of soaking. The calcium loss was 60% in SB-1079 when both germinated and ungerminated grains were washed after simple dipping in lime (table 3). The percentage of calcium loss due to washing decreased in all varieties as the duration of lime soaking increased. Fluctuations in calcium loss might be attributed to differential damage to the kernel that could alter the infusion and leaching process, as reported by Cavins et al. [1].

Effect of the duration of soaking

Regardless of the variety of sorghum used or the method of treatment, increasing the soaking time from simple dipping to four or eight hours resulted in a significantly higher calcium content (table 2). The levels recorded after four and eight hours of soaking were comparable. In contrast, further increases in the

TABLE 2. Mean calcium-content values of treated sorghum for each treatment variable, and least significant differences

  Mean LSD at 1%
Variety   2.3
SB- 1079 200.8  
DSH-1 200.9  
CSH-5 201.2  
SB-905 184.2  
Treatmenta   2.3
3 209 4  
4 171.6  
2 167.8  
Soaking time   2.57
4 hours 231.2  
8 hours 231.0  
16 hours 218.3  
32 hours 209.0  
dipped 94.1  
Germination   1.6
germinated 204.1  
ungerminated 188.4  
Washing   1.6
unwashed 223.7  
washed 169.7  

Means printed in italic type within the same section of the table do not differ significantly among themselves at the 1% level of significance. a. Treatments as listed in the note to table 1. soaking time to 16 or 32 hours caused a significant reduction in calcium content. This reduction might have been caused by separation of the horny endosperm cells, resulting in calcium leaching, as reported by Martinez [6].

The results of the experiment reported here show that soaking of germinated sorghum grains in lime for four to eight hours followed by drying in the shade for 24 hours is the best method for achieving calcium enrichment.

Since unleavened flat bread (rot)) is one of the most commonly consumed sorghum products in India, as an ancillary experiment we compared the organoleptic quality of rotis prepared in the usual way and prepared from grain treated by the methods described in this study. No differences were found between the control and treated sorghum rotis with regard to appearance, colour, texture, flavour, or overall eating quality at either the laboratory or the consumer level.


Four varieties of sorghum grain (SB-1079, DSH-1, CSH-5, and SB-905) were subjected to four methods of treatment with saturated calcium hydroxide solution (soaking and drying with and without washing for germinated and ungerminated grains) for five different periods: dipping only, or 4, 8, 16, or 32 hours of soaking. Among all the varieties, treated germinated grain showed a higher calcium content than treated ungerminated grain. Irrespective of the method or duration of soaking, SB-905 showed a significantly lower calcium content than the other varieties. A maximum calcium content of 253.6 mg per 100 g of grain was obtained in the DSH-1 variety when germinated grain was soaked and dried, compared to a 55.0 mg per 100 g in the untreated sample.

Washing after soaking resulted in a decreased calcium content in both germinated and ungerminated grains. Increasing the soaking time from simple dipping to four or eight hours resulted in a significant increase in calcium content. Further increases in soaking time to 16 or 32 hours caused a significant reduction in calcium content.

TABLE 3. Percentage reduction in calcium content of treated sorfhum due to washing after soaking




SB-1079 DSH- 1 CSH-5 SB-905 SB1079 DSH-1 CSH-5 SB-905
Dipped 59.0 27.6 16.0 27.6 59.9 48.8 30.5 49.3
4 hours 17.0 0.5 21.0 0.6 32.4 45.8 28.0 18.7
8 hours 9.0 27.5 4.1 13.3 10.5 35.0 29.8 17.4
16 hours 16.0 4.7 12.3 9.3 7.4 37.4 14.2 38.9
32 hours 44.0 16.3 46.9 29.9 11.9 8.0 17.3 14.4


1. Cavins JF, Lessin CW, Inglett GE. Infusion of grain sorghum with Iysine, methionine and tryptophan. Cereal Chem 1972;49:605-08.

2. Price ML, Butter LG, Rogler JC, Featherston WR. Overcoming the nutritionally harmful effects of tannin in sorghum grain by treatment with inexpensive chemicals. J Agric Food Chem 1979;27(2):441-45.

3. Muindi PJ, Thomke S, Ekmar R. Effect of Magadi soda treatment on the tannin content in in vitro nutritive value of grain sorghums. J Sci Food Agric 1981;32(1):25-31.

4. Association of Official Analytical Chemists. Official methods of analysis. Washington, DC: AOAC, 1980:224.

S. Deosthale YG, Belvady B. Mineral and trace element composition of sorghum grain: effect of variety, location and application of nitrogen fertilizers. Indian J Nutr Dietet 1978;15:302-08.

6. Martinez ML. Factors affecting textural behaviour and calcium content of corn during lime treatment process. Dissertation Abstracts International 1977;38(5):2108.

Workshop reports

Report of the technical meeting on software for nutritional surveillance

Edited by Ronald R. Fichtner, Kevin M. Sullivan, Frederick L. Trowbridge, and Beverley Carlson

The US Centers for Disease Control (CDC) and the Interagency Food and Nutrition Surveillance Programme (IFNS)* jointly convened a technical meeting in February 1989 in Atlanta, Georgia, USA, to consider the future development and dissemination of anthropometric microcomputer software for the assessment of nutritional status.

A principle objective of the meeting was to stimulate the availability of reliable and easy-to-use microcomputer software for the analysis of the nutritional status of young children through anthropometric assessment. To the extent possible, these tools for nutritional surveillance should stand on their own in the sense that the user should be able to learn and apply them through self-study and that they should provide all the computational functionality required. In order for the software to be widely accessible, it must also be available free or at minimal cost.

Furthermore, to be of continuing use, the software must be supported by recognized institutions able to disseminate and update software, respond to queries from users, and troubleshoot technical problems that may occur. The coordinated effort of the UN agencies and of the institutions that are supporting software development will make it possible to extend broadly the accessibility and use of anthropometric software. The IFNS is one avenue for this process [1].

Those attending the meeting included representatives from WHO, the Pan American Health Organization (PAHO), UNICEF, CDC, and other organizations involved in nutritional surveillance and assessment. The developers of the anthropometry software packages reviewed were also in attendance. The participants assessed the needs of software users, including data entry, calculation of anthropometric indicator values, database management, data analysis, and the transfer of files among existing software packages. The principal packages were then reviewed and compared, and a consensus was established on requirements for future software development and plans for training and broad dissemination.


The assessment of the growth status of children based on measurements of height and weight is a fundamental tool in the conduct of nutritional surveys and surveillance. The growth reference curves recommended by WHO have been adopted internationally for evaluating the nutritional status of children. Using a single reference population allows for standardized comparisons between different nutritional studies at the national and international levels. When applied to population data, the reference provides estimates of the prevalence of abnormal anthropometry, i.e. undernutrition or overnutrition. In addition, the reference is used to monitor the growth of individual children and to measure the effect of nutritional interventions.

The growth reference curves provide Z-scores, percentiles, and percentage of median values, for stature for age and weight for age for children younger than 18 years old, and weight for stature for males with stature less than 145 cm and females with stature less than 137 cm [2]. Before the proliferation of microcomputers, these standards were available only in graphical or tabular form or as subroutines executable on mainframe computers. The latter was feasible because the references were constructed as families of continuous mathematical functions. These functions can be assimilated by computer programs to yield precise values for the anthropometric indices.

Recent rapid technological changes in microcomputer hardware have enabled these anthropometric subroutines and other health-care software to run on microcomputers, making it possible to calculate growth status rapidly and easily, even in field locations [3], but there has not been an opportunity for co-ordinating efforts to develop and disseminate software, and there is a need to expand the user community.

To address these needs, the CDC and IFNS sponsored the present meeting. The attendees discussed the needs of microcomputer anthropometric software users, reviewed existing software, and defined requirements for future software development.

Assessing the needs of software users

The participants at the meeting endorsed the concept of stand-alone software for nutritional surveillance. They concluded that a single, self-contained package simplified training and standardization and provided ease of use. They agreed that a microcomputer software package should conform to the following minimum specifications:

Basic hardware requirements

-IBM PC-compatible.
-A minimum of two floppy diskette drives.
-256 KB of RAM.
-Non-graphics monochrome monitor.
-DOS 2. l or higher.

Software requirements

-A dual-mode system that offers (l) a subset of the program for new users, incorporating only basic software functions, and (2) the full package with more extensive features for advanced users.
-Calculation of standard anthropometric indices from the reference.
-Basic file-management functions, including record and field editing.
-Interpretation of dates in m/dry and dimly formats.
-Conversion of weight and height measurements to/from US and metric.
-Import/export of files in ASCII, comma-delimited, and .DBF formats.
-Production of standard anthropometric summary tables, user-definable cross-tabulations, and variable means.
-Availability of basic graphics.
-Screens available in English, Spanish, or French.
-Help screens for on-line assistance to users.

Other requirements

-User documentation available in English, Spanish, or French.
-An on-line tutorial for new users (part of the software package).
-A periodic newsletter distributed to notify users about updates and new versions of the software.

Review of existing software

The co-sponsors of the meeting identified five relevant software packages for review and comparison (table l). During the meeting, each package was demonstrated by the organization responsible for its development and support.


The Division of Nutrition, Center for Chronic Disease Prevention and Health Promotion (CCDPHP), CDC, recently developed Anthro. This software incorporates batch processing of files and an anthropometric calculator for generating anthropometric indices (without storing the database). It was written in the dBase programming language to accommodate users who collect surveillance data using dBase.


With registered users in more than 50 countries, this widely-distributed package, also developed by the Division of Nutrition, CCDPHP, CDC, is now in its third version [4]. It features three modules: Entry, for interactive data entry, editing, file creation, and anthropometric calculations; Batch, for anthropometric calculations of files in ASCII format using a batch process; and Tab, for cross-tabulations of CASP files.


The Epidemiology Program Office, CDC, developed this software, which is written in the PASCAL programming language [5]. EpiInfo was originally created to support epidemiological investigations that required flexible questionnaire development and rapid entry and analysis of data. Now in its third version, EpiInfo has retained its original features while evolving into a stand-alone, general-purpose, epidemiological software package with extensive data management and analytical capabilities and with basic graphical functions. Although the current version of EpiInfo cannot calculate anthopometric indices, a developmental version that uses a PASCAL anthropometric subroutine was successfully demonstrated at the meeting.

Version 5 of EpiInfo, scheduled for availability in the autumn of 1989, will be modified to incorporate an anthropometric calculation module. This module will replace CASP and provide users with CDC's anthropometric subroutines coupled with the more powerful data management and analytical capabilities of Epilnfo.

TABLE 1. Comparision of featurea of anthropometry software systems



Anthro CASP Epilnfo IQ/FEWS ISSA
Hardware/software requirements, programming language
minimum RAM hard disk 384K 256K 320K 320K 384K
minimum DOS version required 2.1 2.1 2.1 3.0 2.1
programming language dBase BASIC PASCAL C C
Database capabilities
customized input screens - - Y Y Y
Merge/Subset file - Y Y Y Y
Index Sort file - - Y Y Y
customized reports - - Y Y Y
Import/Export facilities Y Y Y Y Y
Analytic capabilities
frequencies Y Y Y Y Y
cross tabulations Y Y Y Y Y
means Y Y Y Y Y
more advanced statistics - - Y - -
graphics - Y Y - -
batch processing Y Y - Y Y
anthropometric calculator Y Y - - -
User support
automatic on-line help - - - - Y
tutorial - Y Y - -
prompt messages Y - Y Y Y
training - Y Y Y Y
software in languages other than English          
Y - - Y -a
documerrtation in languages other than English          
- Y Y Y -a

Y=yes;- =no.
a. Spanish version in preparation.

International Questionnaire Development System (IQ)

The Tulane School of Public Health and Tropical Medicine, which is responsible for the field health and nutritional component of the Famine Early Warning System (FEWS) project of the United States Agency for International Development (USAID), developed this software. The university provides technical assistance to many organizations in the area of nutritional surveillance. IQ emphasizes data entry and data quality control procedures, but also supports direct anthropometric calculations and limited data management and nutritional status report generation [6]. IQ is written in the programming language "C," requires DOS 3.0 or higher, and permits users to save and standardize questionnaire protocols.

Several technical enhancements to IQ are being made to increase its power as a data-entry and analytical tool. Food and nutrition survey methods manuals are being developed to provide an entire complement of methodological tools for applied survey research. Documentation is already supported in French and is soon to be available in Spanish.

Integrated System for Survey Analysis (ISSA)

ISSA was developed by the Demographic and Health Surveys programme (funded by USAID) of the Institute for Resource Development (IRD), a subsidiary of the Westinghouse Electric Corporation. Written in "C," it supports the creation, maintenance, and analysis of data sets, including those collected via complex survey designs, and is especially suited to handle large data sets from countrywide surveys, which is its principal application. ISSA has a broad range of functions that include its own procedural language for users and full anthropometric calculation. Complete implementation of ISSA with all its modules requires 640 KB of RAM, and use of a hard disk is recommended.

Other software

The CDC's mainframe FORTRAN anthropometric subroutine, which has recently been adapted to the microcomputer environment, was demonstrated at the meeting, In addition, the CDC has available full anthropometric subroutines in the PASCAL, FORTRAN, and dBASE programming languages for users wishing to incorporate them into customized applications.

Another larger package, the Data Entry, Validation, and Analysis System (DEVA), was developed by the Food and Agriculture Organization for small, project-specific household surveys. DEVA features an anthropometric calculator and requires integration with two commercial software packages that are needed for full system functionality.

Results of the meeting

Anthropometric software offers a great many microcomputing applications, and software may have to be developed or modified to meet specific requirements. Nevertheless, co-ordinating software development to maintain comparability of analytical results and to share revisions and upgrades among all users will prove valuable. To the greatest extent practical, the development of new software and its documentation will adhere to the meeting's recommendations for minimum system standards.

Those attending agreed that the network of software users and developers that was established at the meeting would be continued and that the results of future efforts would be shared. It was agreed that CDC will take the lead to sustain this network and co-ordinate collaborations among the agencies and institutions.

Sources of information

Additional information on the principal software packages can be obtained from the respective sponsoring organizations. [The programs listed are available without cost or at only a nominal charge for developing-country institutions that have a need for them. -Editor]

Anthro and CASP Statistics Branch Division of Nutrition, CCDPHP Centers for Disease Control Atlanta, GA 30333, USA


Division of Surveillance and Epidemiology Studies Epidemiology Program Office Centers for Disease Control Atlanta, GA 30333,USA


School of Public Health and Tropical Medicine Tulane University 1501 Canal Street, Suite 713 New Orleans, LA 70112, USA ISSA/DHS IRD/Westinghouse 8850 Stanford Blvd., Suite 4000 Columbia, MD 21045, USA


Beverley Carlson, UNICEF Jonathan Gorstein, WHO Miguel Gueri, PAHO

Rafael Flores, Institute of Nutrition of Central America and Panama (INCAP)

Luis Fajardo, Universidad del Valle, Cali, Colombia Felix Lee and Nancy Mock, School of Public Health and Tropical Medicine, Tulane University, New Orleans, La., USA

Trevor Croft, IRD/Westinghouse, Columbia, Md., USA

Fred Zerfas, Logical Technical Services, Inc., Chevy Chase, Md., USA

Eddas Bennett, Kelly Bussell, Andrew Dean, Ronald Fichtner, Richard Peck, Jimmy Simmons, Norman Staehling, Kevin Sullivan, and Frederick Trowbridge, Centers for Disease Control, Atlanta, Gal, TTCA


1. IFNS: guidelines for project preparation. Interagency Food and Nutrition Surveillance Program. New York: UNICEF, 1988.

2. Dibley MJ, Goldsby J, Staehling N, Trowbridge FL. Development of normalized curves for international growth reference: historical and technical considerations. Am J Clin Nutr 1987;46:736-48.

3. Wilson RG, Echols BE, Bryant JH, Abrantes A. Management information systems and microcomputers in primary health care: a report of an international workshop. Geneva: Aga Khan Foundation, 1988.

4. Jordan MD. Anthropometric software package tutorial guide and handbook. Version 3.0. Atlanta, Ga, USA: Centers for Disease Control, 1986.

5. Dean AD, Dean AG, Burton A, Dicker R. Epilnfo computer programs for epidemiology. Version 3. Atlanta, Ga, USA: Centers for Disease Control, 1987.

6. Lee FF, Bertrand WE, Mock NB. International questionnaire development system. Version 4.2F. New Orleans, La, USA: Tulane University, 1988.

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