The African Postharvest Losses Information System - is a network of local postharvest experts supported by a database and loss calculator that provide cumulative cereal weight loss estimates from production for Sub-Saharan Africa by province, by country and by region. APHLIS was the initiative of the European Commission's Joint Research Centre and developed by the Natural Resources Institute (UK) and German Ministry of Food. APHLIS can be found at http://www.aphlis.net. There is a plan to expand APHLIS with the support of the Bill and Melinda Gates Foundation. The new project, called APHLIS+, will increase the range of crops for which loss estimates are available and will develop risk warning for certain postharvest problems.
A loss value not from a single measurement but from multiple measurements, where at each measurement the previous loss has been taken into account. The most common example is where losses from production are estimated. With each subsequent loss in the postharvest chain the amount of original production that remains becomes smaller. Consequently even if relative (%) weight losses of two particular links in the postharvest chain are identical, say both are 10%, the absolute loss (tonnage) will be greater at the earlier of the two links since the remaining production will have been greater at the earlier link. A special case of this is farm storage losses where farmers are consuming grain during the storage season. Losses become greater with time so that each lot of grain that is consumed will have been subject to a different degree of loss. The cumulative storage loss is the weighted average of each loss measure not just the loss observed in the grain that remains at the end of the storage season. In the very early days of loss assessment it was common to omit cumulative effects from loss calculations so that loss values would appear unduely large.
Downloadable loss calculator
The same algorithm as used in to the web-based APHLIS loss calculator can be downloaded from the APHLIS website as an Excel spreadsheet. The User can work at any geographical scale, can alter the default values, and can make estimates of production if data on quantities of threshed grain are available.
A formal market is one that is subject to a specified standards and in which food commodities are traded and paid for according to one or more grades. Conversely, an informal grain market is one where commodities are not traded at specific grades and there is no specific relationship between quality and price.
A grain standard defines the quality of grain traded in a formal market. Grain standards comprise a set of one or more grades that define the maximum limits for impurities and imperfections (e.g. foreign matter, mouldy grain, discoloured grain etc.), the minimum limits of desirable qualities (e.g. test weight) and a maximum moisture content.
The process of estimating the extent of losses. The assessment may be undertaken by measurement or by a questionnaire survey where the opinions of those affected by losses are gathered. Actual measurement of loss is considered much more accurate that questionnaire survey. The measurement of losses is time consuming but is easier and quicker using visual scales.
The moisture content of grain is a way of expressing how much water is contained within the grain. This usually expresses the weight of water as a proportion of the weight of the grain containing this water (wet weight) rather than the weight of water as a proportion of the weight of grain without water (dry weight). Moisture content is measured by drying grain in an oven under carefully controlled conditions or, more conveniently, using an electrical meter.
Postharvest loss, cf. weight loss and quality loss.
This is a reduction in the quality of food so that its market value is reduced. Quality is usually assessed using an official grading system that specifies the appearance, shape and size of food commodities as well as aspects of purity, variety etc. Nutritional loss is a component of quality loss but this type of loss requires specialist techniques to measure, i.e. is not measured by official grading, and in the case of grains may include the problem of mycotoxin contamination.
Visual scale for loss assessment
A rapid loss assessment technique that can be used to estimate weight and quality losses that arise from biodeterioration. A series of food commodity classes are established against which any commodity sample can be compared and then classified. The classes usually have some meaning in terms of the end use of the commodity, i.e. suitable for a formal market, suitable only for informal market, suitable only for animal feed etc.
Loss in weight from production due to poor postharvest handling or attack by moulds, insects pest etc.. Does not include weight changes due to change in moisture content. It is a measure of loss from the human food chain. May be presented as an absolute loss, e.g. as a tonnage or as a relative loss such as a percentage from production.