Research and measurements of the impact of mechanical harvesters on fresh blueberries

Research and impact measurements of mechanical harvesters on fresh blueberries

21/09/2015

Chile is the largest exporter of fresh blueberries in the world, but the USA is the world's largest producer of this fruit and devotes most of it to domestic consumption. At 2013, the US produced four hundred thousand tons of blueberries with an estimated price for the producer of US $ 1000 million. The United States, currently has fresh blueberries throughout the year for imports coming from different countries in Latin America, mainly from Chile.

The blueberry as fresh fruit is susceptible to damage in its cultivation when it comes to mechanical harvest because the fruit is beaten, so it has a very short postharvest life, softening faster in refrigerated storage, compared to harvested fruit manually or without hitting.

Generally a blueberry packing line consists of a funnel to transfer the fruit that comes in boxes from the orchard to a conveyor line that moves the fruit to an equipment that removes the trash, then to an electronic sorter, inspection line, and finally to a clamshells filler team. The blueberries fall as they are transferred from one part of the packing line to the next.

The past 13 and 14 of August was held in the Aula Magna of the Faculty of Agricultural and Forestry Sciences of the University of La Frontera, in Temuco, the "II Chilean Congress of Berries 2015". At the event, Fumiomi Takeda, fruit researcher at the Department of Agriculture in Kearneysville, and Associate Professor at the Faculty of Engineering, at the University of Georgia, USA, shared with those present his research that consisted of measuring the mechanical impacts occurred in the line of packing quantitatively with a mini-sphere with sensors called blueberry impact recording device or BIRD. BIRD I and II were used to evaluate 11 packings in Florida, Georgia, North Carolina, and Michigan in 2013 and 2014 and eight packings in Chile (Linares, Cauquenes, Parral, and Chillán).

The data revealed that the largest impacts (~ 230 g) were recorded when the sensor fell into the funnel that was above the clamshells filler in eight empty lines. The cumulative peak G data showed a strong correlation with the total fall height, indicating that reducing this total height in a packing line could reduce the damage level. When the transfer points were quilted with Poron sponge strips, significantly lower levels of impact were recorded. BIRD I and II also recorded minor impacts when they were run on lines with fruit. The severity of the damage by hit resulting from fruit that was released from different heights was related to the impact data recorded by the BIRD sensors.

In the USA, the harvest of blueberries for the fresh market is made with machines that pass over the plants even when these harvesters cause damage by hitting the fruit. The BIRD I was used to measure the quantity and magnitude of mechanical impacts generated by the three main commercial types of mechanical blueberry harvesters (rotary, punching, and rocking chairs).

The sensor was placed in cranberry plants and the plants were harvested under standard operating conditions such that the sensor was removed from the plant and experienced the impact forces typically found in a commercial operation. The data collected by the sensor revealed that the harvesters "golpeadora" and "rocking chair" not only generated more number but also greater magnitude of impacts than the "rotary". The analysis suggests that these disparities were mainly due to the different mechanisms in motion, materials in contact surfaces, and designs between the three harvesters.

Comparison of two packing lines: Height of falls (left) and impacts (right) in transition points.