ASCOT Library Zabali Campus

This volume stems from the joint and independent efforts of many who have contributed ideas as well as manuscripts.
Contributors and Authors
Harpers Ferry, WV, Meeting, September 8-10, 1976
Slough, England, June 13-24, 1976
Authors
Preface
When world food production is viewed as a system, loss and deterioration is seen as a major food-limiting factor. Postharvest loss reduction would benefit from reliable loss estimates and cost/benefit comparisons; improvements also must be acceptable and feasible to introduce.
I. Introduction. K. L. Harris and C. J. Lindblad --
Determination of postharvest grain losses requires a blending of, and concepts from, several sciences. --
II. Terms of Reference. K. L. Harris and C. J. Lindblad --
A. Definitions --
Postharvest, losses, food, insects, microbiological defined. --
B. Planning: An Overview for Project Administrators. K. L. Harris Project planning involves many disciplines and concepts, from national priorities to logistics and local cultural values. --
C. An Overview of the Postharvest System: The Food Grain Supply Pipeline. K. L. Harris, W. J. Hoover, C. J. Lindblad, and H. Pfost --
Determination of losses should proceed stepwise from understanding the overall grain-food pipeline to location of leaks and sites where losses are relatively important, can be assessed, and are amenable to loss-reducing interventions. --
D. Preliminary Examination of Specific Problem Points and Making On- Site Rapid Appraisals. G. G. Corbett, K. L. Harris, H. Kaufmann, and C. J. Lindblad --
Rapid on-site appraisals (30-60 days) are both workable and useful to determine feasibility for further investigations and for some inputs, and to delineate specific problem points. --
III. Social and Cultural Guidelines --
A. The Fact-Gathering Milieu. Allan L. Griff --
B. Anthropologic Signposts. C. C. Reining --
Grain loss does not exist independent of human and social influence. Loss assessment and reduction programs need to be seen from within the local setting. Cross-cultural sensitivity and understanding are essential in planning and executing such efforts. Reminders are given on who, what, and how to obtain reliable, useful information on and within the social and domestic organizations and in relation to individuals. Special attention is given to the role of women. --
IV. Representative Sampling, Interpretation of Results, Accuracy, and Reliability. B. A. Drew, with T. A. Granovsky and C. J. Lindblad --
Basic statistical requirements for surveys, sampling, probabilities, and other concepts required in the assessment of losses are presented. --
A. Introduction --
B. Probability Samples --
C. Detailed Instructions --
V. Loss Measurements as Related to Situations Where They Occur --
A. Background Information. D. A. V. Dendy, with K. L. Harris --
Losses are discussed as they occur during threshing, cleaning and winnowing, drying, parboiling, hulling and polishing, and grinding. B. Guidelines for Performing Studies of Farm Storage Losses. J. M. Adams and G. W. Harman --
Evaluation of maize losses in small farms is used to explain loss methods development. --
C. Procedures for Measuring Losses Occurring During or Caused by Processing Including Threshing, Drying, and Milling of Most Grains, but not Maize or Pulses/Groundnuts. D. A. V. Dendy, with K. L. Harris --
Guidelines for studying:
• Farm-storage losses
• Total system losses
• Operator-induced losses
• Threshing loss with the straw
• Threshing loss, grain damage
. Maize shelling loss on the cob
• Maize shelling loss, grain damage
Dryer-induced loss, laboratory method
• Dryer-induced loss, method for use in mill
• Batch dryer testing
• Continuous dryer testing
• Grinding loss as bran
Comparison of milling yields by variety Comparison of operators
Comparison of mills
Due to insect damage
• Rice milling losses
Batch process
One-stage continuous process Two-stage continuous process
• Rice hulling losses
• Rice polishing losses
VI. Standard Measurement Techniques --
A. Preamble to the Methodology. K. L. Harris and C. J. Lindblad --
General background of previous work, previously used estimating procedures and techniques, standardization of results. --
B. Losses Caused by Insects, Mites, and Microorganisms. J. M. Adams and G. G. M. Schulten --
An explanation of several techniques based either on the weight of a measured volume of grain compared with a pre-loss standardized weight or on the separation of damaged kernels and the comparative weights of damaged to undamaged calculated to the whole sample. Also a conversion factor/percent damage method. Weight/unit volume, counts and weights of damaged and undamaged kernels, percent of damage and weight loss, and conversion factor/percent damaged methods are presented. --
• Standard volume/ weight method for damage by insects and microorganisms
• Modified standard volume/weight method when a baseline cannot be determined
• Count and weigh method
• Converted percentage damage method
C. Losses in Grain Due to Respiration of Grain and Molds and Other Microorganisms. R. A. Saul, with K. L. Harris --
Weight loss due to grain respiration is unimportant until the moisture is so high that serious microbial deterioration occurs and rejection for food use becomes the dominant factor. Tables are given for calculating losses based on time, temperature, moisture, and physical damage. A formula is given for calculating losses based on weight of damaged and undamaged kernels. Rationale and techniques are presented for basing losses on locally applied rejects.
D. Rodents
1. General Considerations, Direct Measurement Techniques, and Biological Aspects of Survey Procedures. W. B. Jackson and M. Temme --
Each rodent ecosystem has features that tend to make it unique. Loss evaluations require preliminary investigation to establish an environmental and loss perspective as to what features require and are amenable to assessment. --
2. Loss Determinations by Population Assessment and Estimation Procedures. J. H. Greaves --
When they can be undertaken, census and food-intake procedures will give useful results. Three techniques are described:
• Survey for infestation
• Census trapping and food intake calculation
• Lincoln-Peterson method for population estimation
E. Measurement of Losses Caused by Birds --
By brief summary only. --
F. Moisture Measurement. T. A. Granovsky, G. Martin, and J. L. Multon --
The measurement of grain moisture is critical for proper assessment of weight changes during storage. (See Appendix C for methods.) A nomograph is given for calculating weight changes resulting from moisture content changes. --
VII. Operations Standardization and Control --
From field observations and sampling through analysis and reporting results, the operation requires standardized procedures and written operations directions and reporting forms. Supervision and built-in controls are required. --
A. Handling of Samples in the Laboratory. T. A. Granovsky --
B. Operations Manuals and Laboratory Records. T. A. Granovsky and K. L. Harris --
VIII. Application and Interpretation of Results --
In assessing losses, it is important to plan and follow a system that will produce the information required, be it related to traditional patterns, proposed interventions, biological parameters, or loss/benefit values. --
A. The Chronologic Approach: Losses as Reflected by Use Patterns. J. M. Adams --
There is a need to assess losses in grain as they are related to the use pattern so as not to base total loss figures on the final condition of residual grain. --
B. Losses and the Economist. M. Greeley and G. W. Harman --
To the economist, "losses" refer to changes in value, and the magnitude of the effort to reduce losses is often dependent on the magnitude of the monetary losses. Loss surveys are viewed from this perspective. --
C. Conversion Into Monetary Values. E. Reusse --
After physical and quantitative assessment, food losses need to be expressed in monetary terms. This is necessary to establish a common denominator for cost/benefit analysis in which cost (investments in potential improvement measures) and benefits (expected reduction of food losses) can be weighed against one another. --
Appendices --
A. Sampling Grain --
1. Comments on Probing Techniques and Probes --
2. Techniques for Sampling Bagged Produce. P. Golob Examining every grain in a lot is not physically possible. Thus, the quality of the whole has to be judged on the basis of a sample. The sample must be representative of the individual bag, stack, or lot from which it is drawn. Various techniques to obtain representative samples from bagged commodities are described and discussed. Emphasis is given to problems of probing for samples. --
B. Tables of Random Numbers and Their Use. B. Drew and T. Granovsky --
Sample selection by means of randomization is not an unorganized hit or miss process to assure that an intentional or unintentional bias will not be introduced during sample selection and sampling. Procedures for meeting these requirements are discussed and described. A table of random numbers is given. --
C. Moisture Meters --
A review to help the prospective buyer find which of the many meters best meets the work requirements. Data sheets are given. --
1. Guidance in the Selection of Moisture Meters for Durable Agricultural Produce. T. N. Okwelogu --
List of meters and characteristics. --
2. Table of U.S. Department of Agriculture, Federal Grain Inspection Service List of Meters Used in the United States and Their Manufacturers, April 1978 --
3. French Table of More Recent Moisture Meters with Acceptable Accuracy --
D. Assessment of Profitability of Alternative Farm-Level Storages. M. Greeley --
An approach is given to evaluating three methods of storage improvement for Andhra Pradesh, India. In each case, a cost/benefit ratio is determined and compared.

"When world food is viewed in terms of a system of production, distribution, and utilization, it becomes obvious that in our attempts to improve the system we have allocated most of our resources to the production component. Distribution and utilization have been comparatively neglected. But hunger and malnutrition can exist in spite of adequate food production. They can be the result of unequal distribution of food among nations, within nations, within communities, and even within families. Loss and deterioration of available food resources further adds to the problem. Hence, maximum utilization of available food is absolutely essential.
Of the agricultural commodities consumed as food, grains (cereals, legumes, oilseeds) contribute the bulk of the world's calories and protein. The food grains system is depicted in Fig. 1, which shows the many points at which losses of food occur. The reduction of postharvest grain losses, especially those caused by insects, microorganisms, rodents, and birds, can increase available food supplies, particularly in less developed countries where the losses may be largest and the need is greatest.
In September 1975, the growing international awareness of the need for reducing postharvest food losses culminated in a resolution of the Seventh Special Session of the United Nations General Assembly stating that "the further reduction of post-harvest food losses in developing countries should be undertaken as a matter of priority with a view to reaching at least 50% reduction by 1985." Yet, following the Seventh Special Session, an Interdepartmental Subcommittee reviewed past and current activity and concluded: "There is no agreed methodology of post-harvest loss assessment. Moreover, loss data are generally unrelated to the cost of loss reduction."
In its interpretation of available information on losses, the Subcommittee concluded that "there can be no agreed single figure for the percentage of post-harvest losses on a global scale or even on a national basis. There is clearly a need for more accurate assessment of these losses, to establish firm justification for the development and introduction of measures designed to reduce them where the cost/benefit ratios of corrective measures are favorable."
The goal of this volume is to provide postharvest grain loss assessment methods yielding standardized and reproducible results so that effective grain loss reduction efforts can be undertaken in developing countries. The assessment information from such a manual may provide essential justification and motivation for introducing measures designed to reduce grain losses.
This volume is prepared in large part for use by policymakers who need loss information both in determining national priorities and requirements and in bringing their efforts to bear on the small farmer and other small-volume grain handlers. It is also directed to the individual investigator who seeks a basic guide in his specific investigations. The manual is aimed primarily at loss assessment in developing countries.
Although a methodology for assessing postharvest grain losses will not in and of itself reduce those losses, the methodology is essential to postharvest operational programs so that priorities for loss reduction can be determined. In addition to serving as a much-needed assessment tool, the methodology and other activities proposed can serve as a means to persuade all concerned that change is necessary and that effective techniques for reducing losses are available. Even financial constraints can disappear when priorities are reordered.
As detailed later in this Preface and in Chapter II, the enormous variability of local postharvest situations dictates that no complete or definitive loss assessment methodology for all situations is now possible. Thus, this edition is not proposed as a final and absolute piece of work. For example, there exists very little experience which can be drawn from in loss assessment of cereal grains such as sorghum, millet, teff, and major oilseeds. Judgment will be required to adapt known assessment methods to those grains and to other loss situations not dealt with in sufficient depth here. Further, the editors realize that expansion and refinement of the loss assessment techniques presented in this manual are desirable and necessary as a continuing process.
Increasing food production by increasing acreage or yield per acre has been a readily applied concept while reducing losses to increase food supplies was a less obvious strategy. This occurred in spite of the availability of a considerable body of information on postharvest grain losses, and in spite of several decades of research and development on losses and their control.
Progress in reducing postharvest food losses requires the identification and elimination of the constraints to the application of existing technology. The major constraint may be a lack of finances, but it is equally possible that lack of knowledge and of trained personnel, as well as political and cultural constraints, exists. In 1975 an FAO Subcommittee position paper identified four constraints to the effective use of available technology for reducing on-farm losses: 1) lack of arrangements for producing the necessary inputs, 2) inadequate distribution channels for the necessary inputs, 3) lack of purchasing power or credit arrangements for the farmer to buy the inputs, and 4) inadequate information to the farmer on how to use the inputs.
While calling for integrated country programs to address these constraints, the Subcommittee stressed the need for creating "an awareness throughout national extension services that on-farm losses are serious and can be significantly reduced." Postharvest loss reduction intervention must be made, however, with specific techniques applied to reduce specific losses. While there may be broad sweeping national needs, not only are the techniques specific, but they must be applied at specific intervention points. Until data are avail- able to show the potential gain from the elimination of losses amenable to reduction, motivation to reduce those losses will not be strong. But aggregate data reflecting losses on a global or even on a national basis are not really useful even if it were possible to obtain them. They are singularly unpersuasive to a farmer, trader, or warehouseman who must lay out his money and time. Losses vary by crop, variety, year, pest and pest combination, length of storage, methods of threshing, drying, handling, storage, processing, transportation and distribution, rate of consumption, and according to both the climate and the culture in which the food is produced and consumed. Given such enormous variability, it is not surprising that reliable statistics regarding the type, location, causes, and magnitude of postharvest grain losses are not available. Yet reliable and objective methods for generating them are needed if priorities are to be given to the reduction of losses. This is needed in regional and national planning and in motivating those organizations which may fund loss-reduction programs, and on down to the local level.
Meanwhile, it is prohibitively expensive and unjustifiable to mount country- wide assessment studies of losses in the whole postharvest system. As detailed in Chapter II, an expert judgment is needed to identify the most serious grain loss points in a country's postharvest food supply system in order to mount in-depth assessment efforts at those high loss points.
Stated another way, changes will not be widely accepted until and unless they are practical for and clearly benefit the individual who is to make the change. Although losses and savings are far from the only elements which must be considered in loss reduction efforts, reliable figures can go a long way in convincing those dealing with grain, and certainly for motivating those
organizations which may fund the loss reduction programs.
Extent of loss is important, but not all-important. Other factors should be considered in deciding on the nature of interventions, or whether to intervene at all: The value of the grain in economic lines; the fact that there will be social change effected by intervention programs; competition or conflict, or both, with other national priorities; effect on price stability and similar economic considerations; the relationship and possible conflict of economic factors that affect the consumer, grain grower, grain trader, and national balance of payments mean that interventions need to be subjected to an integrated, multidisciplinary evaluation and actually field tested within the social and economic structure before they should be implemented on a broad scale.
Both "guesstimates" by knowledgeable people and estimates without factual basis, particularly by people with vested interests, have had a useful role in the past, will continue to be used in the future, and are especially useful when timely opinions are needed as to where the more serious losses occur. In using guesstimates to justify cost/benefit comparisons or to reshape established practices, however, one needs to recognize the possible bias of the estimator: Was it put in perspective by a thorough gleaning of the information, was the judgment based on an in-depth and long-standing knowledge of local or even country-wide conditions, was it made to reveal some situations and cover others? It is critical to understand that guesstimates are the type of estimations that requires the most expert judgment.
If large area or national survey figures are taken without sufficient regard for variations in the individual components, these figures may not be useful to locate specific intervention points.
Finally, we might ask why, in the face of a need for accurate figures that has not gone unnoticed over at least two decades, have there been so many postharvest loss estimates made with obvious biases, and why has a methodology not been forthcoming from the scientific community?
As stated above, the guesstimates have served a useful purpose. They have also been accepted by those seeking national resources and changes as well as by those allocating international resources. Although the scientific need was there, the political- and transformation-related requirements did not call for scientifically derived figures. Now, with increased sophistication and increasingly limited resources requiring benefit-related priorities, there is a need to know what the postharvest losses really are. Without such information, it is impossible to assess needs or to calculate improvements. However, there has been another factor that has stood in the way of assembling this manual. It needs to be mentioned, for its recognition is the key to the present status and ultimate fate of this volume. This factor has been the simple absence of anyone to do the job.
Within the L.I.F.E. consortium, the American Association of Cereal Chemists, under a contract from the Office of Nutrition, Technical Assistance Bureau, U.S. Agency for International Development, has broken the impasse on how and by whom the job was to be done, and it has developed and printed this volume with the hope that it is a volume to be evaluated, tested, and improved by actual use in the field. We look forward to the inevitable changes." -
Kenton L. Harris
Carl J. Lindblad
August 1978