Estimating nutritional postharvest losses – the Nutri-P-Loss project

The amount of food lost or wasted after harvest adds up to 1.3 billion tonnes every year. These losses have a major impact on economic and food security, especially for people in the developing world. Now, a new project is helping us to understand the nutritional implications of postharvest losses for the first time.

Methodologies and tools have been developed through APHLIS (the African Postharvest Losses Information System) that enable us to estimate weight losses along postharvest value chains and, to a lesser extent, the economic value of these losses. However, no methodologies as yet exist for estimating postharvest nutritional losses.

The NUTRI-P-LOSS will examine postharvest losses in terms of their nutritional composition, including the quantity of vitamins, minerals and proteins that are lost. The project is developing a methodology to estimate nutritional postharvest losses along the value chains of food crops in low and middle income countries  – the first in the field to do this.

NUTRI-P-LOSS will focus on important food security crops: cowpea, maize and sweet potato and nutrient losses of the macronutrients (proteins, lipids, carbohydrates) and micronutrients considered to be the most important in terms of deficiencies (vitamin A, zinc, and iron). 

Using a combination of literature review, laboratory studies and field verification in Uganda and Zimbabwe, the project will generate a model for predicting nutrient losses. This tool will link to the new APHLIS+ online platform, which covers an expanded number of crops and types of data, including weight and economic loss.

NUTRI-P-LOSS will estimate nutritional losses related to:

• Quantitative nutritional losses related to dry weight loss (building on existing weight loss methodologies)
• Qualitative nutritional losses related to deterioration of a crop and its nutrients

The steps of the methodology are as follows:

• Estimate physical weight loss using academic literature, and quality losses, using both literature and data from laboratory experiments.
• Feed the data into a predictive model based on an algorithm that can be used for nutritional postharvest loss estimates. Where appropriate, laboratory nutritional analysis will be carried out on selected crop samples.
• Undertake field trials to validate the data obtained with the predictive model.
• Finally, fine tune the model and make it available to users via the APHLIS website.

Measuring nutritional losses along the value chain will deepen our quantitative and qualitative understanding of these losses, which is critical for understanding the contribution of agricultural interventions to nutrition improvement. The tool can be used to generate case studies that support policy recommendations regarding the nutritional implications of postharvest reduction.

The approach offers a cost-effective and sustainable means for the APHLIS network to disseminate the methodology to other countries and apply it to other commodities (cereals, pulses, and roots and tubers).

The two-year project (£250 000), led by the Natural Resources Institute (NRI) at the University of Greenwich, is being carried out in partnership with scientists from the University of Zimbabwe, the National Agricultural Research Laboratories in Kawanda, Uganda (NARL), the International Potato Center (CIP), Purdue University and Iowa State University in the United States, some of which are involved in the APHLIS+ project.

The project comes under the research initiative known as IMMANA or Innovative Metrics and Methods for Agriculture and Nutrition Actions, which is funded by the UK’s Department for International Development (DFID) and coordinated by the Leverhulme Centre for Integrative Research on Agriculture and Health (LCIRAH).

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