The latest techniques for improving the quality of fruit and vegetables in the post-harvest stage have been presented by experts from Wageningen University & Research (WUR) and Dutch association GroentenFruit House. GreenCHAINge Fruits and Vegetables is a four-year project aimed at encouraging the consumption of fruits and vegetables and boosting the sustainability of the supply chain, making them smarter and more focused on quality control. The results of the project include a model that can predict the quality of products after harvest, developing a camera that can measure and analyze the color and quality of fresh produce and a transport and storage conditioning system that cuts down on waste, according to the researchers.

As consumers are eating less meat and plant-based diets are gaining traction, the quality of fresh produce is more important than ever as the food industry demands higher volumes of premium fruit and vegetables. 

This calls for an improvement of the fruit and vegetable supply chains to deliver products of consistent quality. This means that produce should always taste good (a combination of juicy, firm, sweet, ripe and aromatic), have a long shelf life and be easy to use. It is well established that consistent high-quality products result in repeat purchases and, therefore, an increased consumption of fresh produce.

Establishing sustainable methods to cultivate and process the raw materials – in this case, fresh produce – used within the food ingredients industry is vital as companies strengthen their supply chains. This includes future proofing against the needs of the world’s rising population, the rapid onset of climate change, guarding against food waste and increasing shelf life. 

Speaking with FoodIngredientsFirst, project leader for GreenCHAINge and Senior Researcher Post-Harvest Technology at WUR, Eelke Westra, offers further insight into the results of the project.

“The models predict product quality given the conditions in the supply chain (and even before harvest) and fixed values such as ‘grower’ and ‘variety.’ The prediction gives expectations about shelf life which means industry is capable of matching this to the right market,” explains Westra. “In this way, the potential shelf life can be optimally used,minimizing waste.”

“Using the model backwards also gives insight into what conditions and fixed values offer the highest probability for good quality food. This helps sourcing managers to buy fresh produce,” Westra explains. “These types of models benefit from large data inputs, also known as big data, but they also work with soft input like expert knowledge. One of the key findings was what the level of data segmentation should be to have the best performance. For example, if you segment a year in 52 periods (weeks) the performance was better compared to segmentation of three periods (4 months). However, more data was needed in the larger segmentation.”.

The importance of color 
The color of fruit and vegetables is an important purchasing driver with color often being linked to quality. Westra and his team developed a camera system which measures and analyzes the color of fruit and vegetables. Instead of manually assessing one product, this machine works by giving “a complete picture of a whole box of products” which, not only speeds up the entire processes but also provides an objective, accurate and controllable image, notes Westra.

“We have constructed a modular approach to color measurements. The first point concerns the acquisition of a calibrated color image which is the basis for the measurement. Secondly, there is the detection of the so-called ‘Region Of Interest (ROI)’; what in the image is of interest? In our systems, we can create multiple ROI’s in one image. Thirdly, analysis of the ROI. For example, the size of the ROI, absolute or relative relations of one ROI compared to another ROI in the same image, color data of ROI, etc. Fourthly, the processing and analysis of all images.” 

Westra explains that the fresh produce system gives detailed color-related information including aspects such as spots on the skin and discoloration. He notes that this data is superior compared to subjective measurement with color charts or just measuring RGB-color (red, green, blue) values from a digital JPG image. 

“We needed the high accuracy because we want to correlate other sensor data to the found color artifacts,” Westra adds. “With better color measurement we were able to correlate near-infrared spectra to internal brown discoloration of mango fruit. So now we are able to measure internal defects in a non-invasive manner.” 

This is particularly important because it keeps the fresh produce intact. 

“Another benefit is that the system is used as a reference for the development of less detailed systems in situations wher, at the moment, no color measurements are carried out simply because there are no tools available. We have developed a color chart for mushrooms and are working on applications for smartphones.”

Transport and  storage systems
During transport and storage, conditioning systems are used to maintain the quality of fresh produce. The logistics of transporting perishable goods like fresh fruit and vegetables can be a major challenge, so work on this aspect is particularly important to reduce food waste. 

Wageningen experts introduced a floor covering system for refrigerated containers. This resulted in 30 percent fewer temperature differences during loading and less quality loss of perishable products. They also developed a dynamic packaging material that is able to maintain a protective atmosphere with variations in ambient temperature. This extends the shelf life of perishable products, even outside of cooling.

Mangos, grapes, beans, melons, papayas, soft fruit, strawberries, mushrooms, pears and stone fruit were among the fresh produce items used during the research. 

What happens next?
The next steps include getting the results of this project implemented through bilateral projects with industry. Westra also says there is some follow-up research planned in a new project called “Fresh on Demand” which uses the same technology. In addition, all GreenCHAINge Fruit and Vegetable reports have to be completed and will become available in October 2019.

“Improving quality is an ongoing concern in the supply chain from producer to consumer. Knowledge and techniques developed for this purpose, are highly appreciated by our members. They, therefore, work together in projects like GreenCHAINge and Fresh on Demand to work actively to contribute,” says Daco Sol, at GroentenFruit House responsible for Logistics, Supply Chain & Supervision.