 Hello, my name is Angelo Staltzidis. I'm an assistant professor in post-harvest physiology working for the Department of Horticulture of the University of Georgia. I'm very happy to be part of these years at fruit school webinars and I'll be talking to you today about blueberry harvest and post-harvest handling. Let's start with the characteristics of blueberries. Blueberries have to be harvested when they're fully ripe for maximum flavor. As you probably all know, blueberries are highly perishable crops and their shelf life is often limited by increased rates of respiration, softening and water loss, loss of flavor that happens over time, mechanical damage that can occur during harvest, handling or shipping, and a decay that is attributed to many factors such as damage in the skin and high temperatures. Blueberries are high in antioxidants so consumers are increasingly willing to pay to get fresh blueberries. Let's talk about the respiration rates of blueberries and compare them with the respiration rates of other berries. As you can see highlighted in red, blueberries have fairly low respiration rates at both 32 and 67 degrees Fahrenheit. They are at a rate of six milliliters per kilogram hour at low temperatures but it increases more than tenfold at 67 degrees. That shows how important the temperature management is and how important it is to keep the fruit at the lowest safe temperature which is 32 Fahrenheit. If we compare it with other berries such as strawberries, blackberries, cranberries, you see there's a lot of variation. For example strawberries, raspberries and blackberries have high respiration rates and this is why they have a shorter shelf life. For the effluent production rates, on the very right you see the effluent production rates vary. They're very low but they range between 0.1 to 1 BPM. Let's talk about harvesting. You want to train your berry pickets very well and you want to make sure that they follow a number of guidelines in order for the fruit in the end to have the best quality possible. You want your berry pickers to keep their hands clean and to pick all the right berries from one bush before moving to the next one. They need to be trained to harvest only well ripened fruit and they have to leave the mature fruit on the plant for the next harvest. It's not advisable to pick berries that have a reddish tinge, reddish color and mix them with well ripened berries because this way you get a non-homogeneous harvest and then consumers will complain about the unripe berries that they will buy. They need to be placing their hand under the cluster to avoid dropping the berries to the ground. They need to avoid overfilling their hands and they shouldn't be squeezing or rolling the fruit. In general, they have to be very careful not to put any trash or any cold berries into the container. These have to be discarded in the field. You don't want to allow harvested fruit to remain in the sun. They should be moving them as quickly as possible to a shaded or cold location. Toads that are used for harvesting should be kept clean and sanitized daily. Some guidelines about the blueberry harvest and storage. You don't want to harvest when the plants are wet because of a morning dew or rain. However, it's advisable to harvest early in the morning or late in the day to take advantage of the lower temperatures. The harvesting should be done by gently teasing the berries of the bushes to reduce the splitting and bruising. You shouldn't be overfilling the containers or bins in order to reduce compression. Bruising is a big problem and it can occur in many points from the field all the way to the consumer's hands. You want to avoid mishandling the fruit. What is very important to mention, actually the most important thing is that cooling is the number one method of reducing respiration. By talking about respiration, we mean we reduce respiration. We reduce all the metabolic processes. We extend the shelf life of the product. So we're trying to start removing the field heat as quickly as possible if possible in the field when the berries come off the plant. Here are some pictures of how blueberry ripening progresses from pale green to reddish purple to dark purple all the way to dark blue. Obviously the more you move to the right, the better flavor and taste the berries will have. Some more harvest and storage guidelines. You want to pre-cool berries before packing only if these are being packed in a room that is of the same temperature or colder than the berries. We do that because we want to avoid temperature fluctuation at all costs. By fluctuating the temperature and increasing it after pre-cooling, what you get is condensation on the berries. This is not advisable at all because condensation on the berries will cause infections and then it will cause issues in the final quality. So it's advisable if you don't have the infrastructure to keep berries at a constant temperature all the way from the field to the consumer, not to pre-cool. However, the quality will be significantly lower compared to pre-cooled blueberries. It's important to continuously remove field heat from the berries in order to reduce aspiration and therefore decay and quality decline. It's better to pull cold air across berries in order to remove the field heat rather than blowing cold air at stacks of berries from above. You need to make sure you're using containers that have openings to allow for horizontal airflow through the berries. Once the berry temperature has been decreased to the target temperature, that temperature must be maintained all the way to the consumer. You don't want temperature fluctuations and condensation. Machine harvesting with labor shortages has been more and more affordable. However, there are issues you need to take into account when you decide if you're going to invest in such a harvesting method. The height of the berry fall will determine the bruising and how much of it you will get and we know that bruising affects storage life. The more you bruise the fruit, the shorter the shelf life will be. The machine harvesting is used for berries that can be going to processing and it's starting to be used for berries for fresh consumption more and more. There are a lot of differences between varieties and some varieties have bigger stem scars whereas some others are smaller and they are better for machine harvesting. You need to make sure you clean the machine often and remove the debris from it to avoid quality issues. In general, blueberries are less perishable than raspberries and strawberries. They last longer. This is why you see blueberries from other continents. You see blueberries here around from Latin America and you see that pretty much is a year-round crop like bananas for example. If storage is not possible, they can be stored at 41 degrees from two up to seven weeks depending on the cultivator. However, the recommended temperature is 32 degrees Fahrenheit plus or one plus or minus one degree. Internal bruising is a problem and you get it when you see a perfectly fine fruit on the outside. However, internally the fruit has been damaged and you see how it can progress from none other way to very severe on the very right. In general, the waxy bloom that those berries have is something that consumers are looking for. So you want to make sure that you reduce handling as much as possible to avoid removing that bloom from the berries. Here are pictures from the West Coast from California that show a hand harvesting operation of blueberries. The operation is a smaller one and there are a lot of issues I wanted to point out here. First of all, you see how those crates are placed on the ground and then subsequently some of them are stacked one on top of the other. This is an issue. You could have contamination from the ground and you could bring rocks or debris and you don't want that. Also, it's very possible that those berries are sitting in the sun for too long. So you need to have a shaded area nearby to protect the berries from the heat. Here what I'm talking about, they're stacking the berries, the crates that were on the ground, one on top of the other one on top of the other potentially causing food safety issues. Moving on here is how field totes are dumped onto the packing line. It's a conveyor belt moving and then sorting can be done either by hand by workers or it can be done mechanically with optical sorters. There are sorters that can look into the softness or the firmness if I may say of the berry and they will eject the berries that are too soft for packaging. So it's very important because when you have a very soft berry it will start leaking juices and then you will have these juice possibly contaminating the healthy berries around it. Here is how clamshells are filled. They're usually volume filled and then the lids are snapped closed. This is a bigger operation and then you can see here a smaller packing operation where there is someone handling the berries coming from the conveyor belt and the machine is closing the lids of those clamshells. Clamshells are then placed in flats and palletized and then it's very important for all berries to do quality assurance. This should start from the field. You need to be monitoring quality of the fruit for firmness, ripeness, decay incidents as well as other defects. You want to train your crew to make sure that they harvest only the berries that are ready to be harvested and they have no other quality issues and you need to give them incentives for better performance. So it's good to reward the good pickers to improve the overall quality of your harvested berries. Traceability has been very important for the large operations but it's moving even to smaller operations that I can see here in Georgia for example. Here's an example of a receiving area because often we have bottleneck situations where berries are waiting outside to be unloaded. So it's important to invest in a covered receiving area to avoid berries getting really hot from the sun. Again here is quality control. It's strawberries but it happens with all berries. You get quality control at the cooling facility and you have someone measuring the average size, the average weight and the average color of berries to make sure that they meet the minimum standards of the company. And here is a slide that summarizes the recommended storage conditions for fresh market blueberries. As I mentioned before the optimum temperature is 32 degrees Fahrenheit. The optimum relative humidity to avoid water loss is 90 to 95 percent. The rates of respiration of ethylene production are pretty low 0.1 to 1 microliter per kilogram hour at 41 Fahrenheit. And in general we know that blueberries are climactic fruit and they do respond to ethylene. However their flavor does not improve after harvest. So you want to harvest them ready to be eaten. You're not going to expect this to get an improved flavor by treating with ethylene. However removing ethylene from the storage air can reduce disease development. Controlled atmosphere storage can be used. Modified atmosphere packaging for shipments with levels of 15 to 20 percent CO2 and 5 to 10 percent oxygen has been shown to reduce growth of decay. It does reduce aspiration and softening rates and there are ways to cover whole pallets and create a modified atmosphere condition in those pallets. However it's important to mention once again that prompt cooling is a number one way of reducing losses after harvest and it should be done before any atmosphere modification is considered. Cooling. Now for cooling forced air cooling is the best way of cooling blueberries. You want to cool fruit at to 32 Fahrenheit as quickly as possible maintaining a relative humidity of 90 to 95 percent. This way you're going to reduce water loss, decay, perspiration rates and overall extend the post harvest shelf life. In ideal conditions and average good shelf life of blueberries could be up to four weeks. Here is an example of how a forced air cooling system works. You get the berries on a pallet and you get two stacks of pallets on both ends of this big fan. Then the tarp is rolled and the fan is sucking cold air through the berries cooling them down rapidly. It's important to refrigerate all the areas where the berries are sitting and that could be even the loading duct. So there's nothing that should be left at warm conditions because then you can have condensation on the berries because of the high humidity in the air and the temperature change. When berries are shipped across the country or in long distances it's good to provide support so they don't move around, they don't get bruised. And here are some results from work that was done a few years ago by Cecilia Nunes and you see blueberries stored at two different temperatures, 32 and 41 Fahrenheit for up to 14 days. On the y-axis you see the quality rating and the higher the number, the higher the quality rating or the higher incidence of this disorder depending on what we're looking at. So you see here how for berries that were stored at 41 degrees you had taste and aroma declining significantly faster compared to the berries stored at 32 Fahrenheit. And you know on the other hand the firmness had similar declines and so did shriveling. Shriveling increases were similar in both temperatures. Here is some data from a trial that was done a few years ago using Extent which is a product available online to extend the shelf life of blueberries by creating a modified atmosphere. You see this is not a very scientific as I may say survey. In general the higher the value you see the better the quality of the fruit they found. So they compared Extent with control and they had three different storage durations 15 days 28 days and 35 days and according to them to this study it was a small trial actually they found out that Extent was improving the overall quality of berries by reducing dehydration decay color was remaining in the better levels. Other was better in Extent actually was the same taste and salability were all higher in Extent treated fruit compared to control. But again it's a smaller trial so more work has to be done. This is a very interesting experiment that was done from North Carolina extension and it shows on the left the percent of decayed fruit in three different temperatures and you see on the X we have zero to 40 days of storage and on the Y axis we have zero to 100 percent decay fruit. So for fruit that was stored at 72 degrees about 12 days after harvest almost all of them were decaying. For 50 degrees stored fruit about 85 percent of the fruit had decay 18 days after harvest whereas for 34 Fahrenheit degrees stored fruit even after 40 days after harvest about 65 percent of this fruit had decay growing. So you can tell how big of a difference we see and how important it is to reduce the temperature to the lowest safe point. On the right you see the cooling crates for blueberries in forced air cooling versus steel air. So steel air is just sticking a box of berries in a cold room forced air cooling is performing the forced air cooling that I showed earlier. You see the temperature how it changes over time in minutes from zero to 120 so they did for up to two hours. For steel air they started at 75 and they barely went to 74 degrees after after two hours of storage in the cold room. However for forced air cooling they started from 75 and they went down to 58 degrees after about two hours of forced air cooling and you know you see how much more efficient and much more effective is forced air cooling in reducing the fruit temperature. I wanted to check what's going on with new harvesting options so I went online and I found that lately there is a new harvester developed by a professor in Oregon State University and it has a soft surface for catching the berries. The cost is pretty high it's about a quarter million dollars and according to him he's mentioning that machine harvested fruit with this soft catching system will have a similar quality as hand-picked fruit. In general they claim that about 75 percent of the harvest will make it through sorting which is very impressive for a machine harvesting. I'm going to touch upon methods for controlling decay as I said temperature management is very important so CA especially elevated CO2 can mitigate this problem biological control can be used. Irradiation has been used but not commercially ozone in air has been used but it's not being used commercially from what I know and so far the exciteification has been used for blueberry decay control. With that I'd like to thank you for your attention and I'll be happy for to answer any questions you can reach out to me via email. Thanks again for attending and have a good day. Bye.