The Seven Deadly Sins That Impact Produce Quality

Produce quality may seem to lie in the eye of the beholder, but there are seven deadly sins that can cause produce to lose quality before it is purchased or received by the customer. The first deadly sin observed by produce buyers is that many growers do not harvest produce at the correct maturity stage. In many cases, the produce is harvested overripe, leading to increased spoilage and waste.

Years ago, I sold at a famers’ market and needed to augment my early-season tomato supply with a few boxes of tomatoes purchased from the local wholesale outlet. I could not make the trip to purchase the tomatoes myself, so I had my partner make the trek to the wholesaler. When he delivered the 30 lb. boxes of tomatoes, I could see tomato juice oozing through the boxes and fruit flies covering the lids. Each box was filled with overripe and soft tomatoes. At best, the tomatoes were canners, and none of them would grace my display at the farmer’s market. As a grower, ensure you are harvesting your crop at the proper stage of development for your market channel.

The second deadly sin involves the careless handling, packing, and shipping of produce. When fruit is cracked, bruised, or crushed, it has no market value and will reduce your profit margins. One operation that I worked with meticulously harvested tomatoes in their fields and transported them in their truck from their field to their broker.

The boxes were new, the fruit were harvested at the correct stage for the market channel, and the tomatoes were delivered promptly to the broker. The broker called the grower later in the week after receiving the product and informed the grower that they had received complaints from the end customer about the damaged and bruised tomato fruits. At first, the grower was defensive until he realized how badly his dirt driveway was rutted. When he transported the tomatoes from the field, he drove up a driveway that had ruts that would swallow most vehicles. He pleaded with the broker to give him another chance, and prior to his next shipment, he re-graded the farm driveway to eliminate the ruts.

When the tomatoes were delivered to the broker, the grower waited anxiously by phone for another round of complaints. When no complaints emerged, the grower reached out to the broker to check on the last order and hopefully obtain a new one. The broker told the grower that he received no complaints and doubled the tomato order for the next week. Something simple like re-grading the driveway improved his product quality and helped him to retain a valued customer.

The Food Safety Modernization Act has hopefully improved the sanitation of produce in the marketplace, but there are still instances where produce quality has been compromised by soil and organic debris. Improper sanitation is another deadly sin when it comes to marketing fresh produce. When produce is soiled by debris of any kind, it may represent a food safety hazard. When a buyer purchases a soiled product, they will need to wash and re-sanitize the produce before sale, which cuts into their profit margin. When growing and shipping produce, always consider the safety of the produce being shipped and make sure that it is free of soil and debris.

Another of the seven deadly sins for produce growers deals with delays in pre-cooling or suboptimal cooling of produce after harvest. Wholesale market channels like supermarkets and wholesale distributors desire to maximize the shelf-life and quality of the produce that they receive from growers. Sub-optimal cooling or delays in precooling robs produce of its shelf-life and hastens the deterioration and decay of produce.

Sweet corn is one of the most popular fresh market vegetables, but it will ‘lose” approximately 50% of its natural sugars through respiration in one day at room temperature. Sweet corn stored at 32°F will only convert 5% of the sugars in a day, so if the sweet corn is handled properly, a higher quality product will be delivered to the end-consumer.

Improper shipping and storage of fresh produce can significantly impact produce quality and can hasten deterioration and decay. When produce is shipped or stored above the optimal temperature for the crop, it will lose quality due to respiration. If produce is shipped or stored too cold or below the optimal temperature, it may develop cold injury symptoms that may mar its appearance while impacting shelf-life and produce quality.

One Amish tomato grower that I work with has raised high-quality tomatoes for years and sells them through wholesale channels on a regular basis. A new buyer approached him about selling breakers (tomatoes starting to turn color) for distribution through their company. The Amish grower would harvest the tomatoes, sanitize them in his packing house, and then deliver them to the buyer’s warehouse in new, clean, labeled boxes. The grower took great care in handling his tomatoes and was selling to multiple wholesalers in addition to this new buyer.

About two weeks after the first shipment to this new buyer, the grower received an angry call and was told that he was not going to be paid for any of his tomatoes because they were unsaleable. The Amish grower was upset but did not want to be taken advantage of by the new buyer, so he asked if he could pick up any of his tomatoes that had been shipped to the new buyer’s warehouse that had not been sold or distributed. The buyer reluctantly agreed, so the grower arranged to have his tomatoes brought back to his farm so he could see what the buyer was talking about.

When the truck pulled into his farm lane, the Amish grower dropped everything and began examining the boxes of tomatoes that he had shipped to the buyer. The first thing that struck him was that the buyer had returned 100% of the tomatoes that had been shipped. The second thing that he noticed was that the tomatoes had not ripened and that much of the fruit was soft and contained black lesions that were not on the fruit when they were sent to the buyer.

Initially perplexed, the grower decided to contact me (his local Penn State Extension Educator) to visit his operation to look at the tomatoes that had been returned to him. When I looked at the fruit, I told him that it looked like a chilling injury on the fruit, and since he had not received any complaints from his other buyers, I suspected that the problem was probably the result of his buyer storing the tomatoes at suboptimal temperatures in their warehouse.

Improper cooling and handling of produce at any level can impact product quality and marketability. In this case, poor temperature management at the warehouse facility caused the Amish grower to lose revenue even though it was beyond his control. Temperature management is critical when shipping and storing all produce.

Ethylene exposure is one deadly sin that is often ignored by many growers. Ethylene exposure can hasten the ripening and deterioration of some produce. Ethylene is a natural gaseous hormone that is generated in climacteric fruit/vegetables. Climacteric fruits/vegetables are ethylene producers and will continue to ripen after harvest. Non-climacteric fruits/vegetables must be harvested when mature (fully ripe) because they will not continue to ripen after leaving the plant. Tomatoes and cantaloupe are excellent examples of climacteric fruit/vegetables that will ripen after harvest. Common non-climacteric fruits that will not ripen after they leave the plant include strawberries, blueberries, and grapes. Eggplant and cucumber are non-climacteric vegetables and must be harvested when fully ripe for the best consumer quality.

Climacteric fruits/vegetables, as ethylene producers, have the potential to ripen too quickly or deteriorate after harvest. Exposure to ethylene gas in the storage facility or warehouse can hasten the ripening, deterioration, and decay of climacteric fruits and vegetables. Growers can preserve fruit/vegetable quality by carefully managing ethylene gas levels in the produce storage areas.

Air exchange (ventilation) in the storage facility with fresh atmospheric air is the traditional method of ethylene management on the farm and in many storage facilities. Replenishing or replacing the air at regular intervals with ethylene-free air will lower the concentration of ethylene gas in the storage facility, thus delaying the ripening, deterioration, and decay of the produce being stored.

Ethylene gas can also be absorbed or adsorbed through the use of highly porous sheets or pads containing activated carbon or zeolite in the storage facility. Other techniques used to remove ethylene gas in produce storage facilities are primarily used by large facilities because of the cost of implementation and management. Some of the techniques used to manage ethylene gas in storage facilities include ozone-based oxidation, thermal catalytic oxidation, photocatalytic oxidation, biofiltration, vacuum ultraviolet radiation photolysis, plasma, and potassium permanganate. While each of these various systems has a place in the produce industry for ethylene management, most of the growers that I work with utilize ventilation-based systems to manage ethylene levels in their storage facilities to maintain high-quality produce.

The last of the dead seven deadly sins for produce growers involves relative humidity management in a storage facility or warehouse. Too much humidity coupled with poor temperature management creates the perfect environment for post-harvest diseases to inflict damage on the crop in storage. One potato grower that I worked with stored potatoes in a modified bank barn with fresh air inlets providing ventilation to the stored potatoes. This grower could not use electricity because of his religious beliefs and had to rely on natural ventilation to manage the humidity levels in his storage facility.

The grower contacted me to visit his operation because he was observing a significant level of decay in his stored potatoes. When I inspected his storage facility, I needed an umbrella because of the amount of free water in the form of condensation that was forming on the sheet metal that he had affixed to the barn floor above. It was apparent to both of us that we had to increase the air movement in the storage area.

After my visit, the grower modified his storage facility by increasing cross ventilation and by installing a fan that operated off hydraulic pressure. The increased air circulation, coupled with some strategic placement of insulation between the ceiling and the barn floor, reduced the condensation and the subsequent humidity levels in the storage facility. While the storage conditions were not perfect, the grower was able to reduce his storage rot issues dramatically.

Low relative humidity in a storage facility can be just as problematic as excess humidity. When the crop’s relative humidity is below optimum, the stored produce will lose moisture, and the skin will shrivel. Some small-scale growers try to use standard refrigerators for storing produce on their farms. These units are frequently designed to maintain a relative humidity lower than what is recommended for many crops. Refrigerator temperatures may also fluctuate wildly because of their smaller size.

One grower who was using a refrigerated unit could not understand why the produce quality stored in the refrigerated unit was relatively poor when he took it to market. The grower had no way to “audit” the refrigerated unit to evaluate the temperature and relative humidity levels, so I lent him a data logger that he could place in his refrigerated unit that would monitor temperature and relative humidity levels at 15-minute intervals for 24 hours a day for seven days. When I retrieved the datalogger, we plugged it into my laptop and reviewed the data. The temperature in the unit was inconsistent, and it frequently exceeded the recommended 32°F storage temperature that is recommended by postharvest experts for green beans.

When we looked at the relative humidity values in the refrigerated unit, we found that the unit was maintaining a relative humidity level between 65-70%, which was too low for most crops. Most vegetable crops are recommended to be stored at a relative humidity level of 95% to prevent a loss in quality. By auditing the refrigerated unit with the datalogger, this grower realized for the first time that his refrigerated unit was contributing greatly to the quality issues that he was observing in his green beans and other stored crops. — By Thomas Ford, Penn State University Extension

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