Methods for Cooling and Properly Storing Lemons After Harvest

Lemons are beloved the world over for their characteristic sour kick as well as their versatility in juices and beverages, cooking, and baking. The old adage may suggest that one make lemonade when given lemons, but there are certainly countless other options available as well. For lemons to truly pack the most flavorful, nutritious punch it is important that they be properly cooled after harvest and then stored at suitable temperatures until use. Let’s take a look at some key information about lemons and their proper cooling and storage.

General Facts About Lemons

Lemons grow on small evergreen trees that were originally native to southeast Asia. Scientists believe that the lemon may first have developed as a hybrid of the sour orange and the citron. The lemon first entered Europe around the first century AD and by the 1100s they had spread throughout the Arab and Mediterranean regions. Christopher Columbus eventually introduced the lemon to the Americas when he brought lemon seeds to Hispaniola during one of his voyages. By the 1700s lemons were prized by the seafarers for their ability to fight scurvy. Lemons haven’t declined in popularity since and today they can be found all over the world with various year-round cultivars available.

Nutritionally lemons are most well-known for their high concentration of vitamin C. However they also contain other vitamins and minerals and are occasional additives in some traditional medicines, particularly in India. Due to their high acidity their juice is sometimes used as an antibacterial agent. Additionally lemons are extremely popular for their scent and are frequently used in aromatherapy and in cleaning products. Lemons even possess a curious scientific phenomenon: when they are attached to electrodes they can be converted into low-power batteries.

General Information About Cooling and Storing Lemons

There are a number of factors which affect the freshness, quality, and shelf life of lemons. One basic factor is the color of the lemon at harvest. Lemons that are harvested while still green have a longer shelf life but a lower juice content. Conversely lemons that are harvested after they have begun to turn yellow have a higher juice content but a shorter shelf life. However, even disregarding maturity at harvest there are a number of important cooling and storage factors which affect lemons.

Temperature – Lemons should be kept at a temperature of about 50°F to 54°F. Lemons will freeze at 29°F and suffer freeze damage. Meanwhile temperatures that are too warm may hasten degradation and loss of quality.

Relative Humidity – Lemons do best with a relative humidity of about 90% to 95%. If the relative humidity is too low lemons may suffer moisture loss which will result in shriveling and drying out. If the relative humidity is too high lemons may be more vulnerable to problems such as mold.

Handling – To avoid damage lemons should be handled carefully and should not be over-packed. Additionally it is important to begin cooling lemons within a few hours of harvest to slow down respiration and degradation.

Shelf Life – Lemons have a relatively long shelf life when handled correctly. Depending on the maturity of the lemon at harvest it may last up to 6 months in storage. Lemons that are more mature at the time of harvest often have a shelf life of about 4 months.

Methods of Cooling Lemons

Compared to other fruits and vegetables lemons are relatively easy to cool and store. The two most common and suitable methods are:

Room Cooling – Room cooling involves placing the lemons in a refrigerated room such as a cooler and allowing them to naturally acclimate to ambient temperatures. For room cooling to be successful lemons should be placed in the cooler with proper ventilation and space between them.

Forced-Air Cooling – Forced-air cooling is a popular alternative to room cooling because it more rapidly lowers the temperature of the lemons, thereby resulting in faster, more thorough cooling and in some cases extending the shelf life and enhancing the quality of the lemons. Forced-air cooling is accomplished by placing the lemons in a cooler around a fan and then turning the fan on such that it pulls – not pushes – air through the lemons, thereby cooling them much more quickly thanks to the forced circulation.

SEMCO/SEMCOLD LLC is an experienced provider of cooling and storage equipment for the produce industry. We have the systems and equipment necessary to provide outstanding, dependable cooling of lemons and other produce. We can also customize our systems to best fit the scale and demand requirements of the particular customer. Please contact us for more information.

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Effective Methods for Cooling Artichokes After Harvest

Once considered exotic by many Americans, artichokes are becoming a much more common mainstay thanks to their exquisite flavor and versatile culinary uses. Artichokes are frequent ingredients in a variety of dips, tasty components in many salads, popular side dishes, and sometimes even main courses. As with most other types of vegetables and produce the taste, quality, and nutritional value of artichokes is strongly influenced by cooling and storage.

General Facts About Artichokes

The artichoke is a species of thistle that has been cultivated for hundreds of years into the edible vegetable we know today. The domesticated plant is called the globe artichoke, while the wild variety is commonly called a cardoon. Artichokes are native of the Mediterranean region and as such have been cultivated and enjoyed by several prominent ancient societies including the ancient Egyptians, Greeks, and Romans. The Greeks referred to them as “kaktos” while the Romans called them “carduus,” from which their wild name, cardoon, derived.

The artichoke came to the United States in the 19th century when the French introduced it to to Louisiana. Around the same time the Spanish also introduced it to California. Nowadays most of the US supply of artichokes comes from California, which has a suitable climate for crop growth. However, new cultivars such as the “Imperial Star” and the “Northern Star” have
allowed the artichoke to grow further north and in more regions.

Today the artichoke is highly regarded both for its flavor and culinary uses as well as its nutritional value. It has one of the highest antioxidant contents of all vegetables and is known to help improve cholesterol and aid in digestion. Artichokes flowers can also be used to make herbal tea and artichokes are even one of the primary ingredients in an Italian liqueur known as Cynar.

General Information About Cooling and Storing Artichokes

Artichokes are harvested primarily in spring with another peak harvest taking place in autumn. The artichoke plant grows to a height of about 4.5 to 6.5 feet and is cut such that the bulb of the plant and several inches of stem are taken. From there there are several key factors that affect cooling and storage.

Temperature – Artichokes should be pre-cooled to a temperature of at least 41°F or lower within 24 hours of harvest for maximum quality retention. They should then be cooled to a temperature of about 32°F or freezing. Though they are not overly sensitive to freeze damage, temperatures below 30°F should be avoided as there could be some damage or loss of quality.

Respiration and Degradation – Like many fruits and vegetables, artichokes respire and degrade at a faster right at higher temperature levels. Artichokes respire and release heat at about 8 times the rate at 68°F than they do at 32°F. Thus proper cooling and storage will significantly increase shelf life.

Relative Humidity – Artichokes do best at a relative humidity of about 95%. Lower humidity levels will result in moisture loss and a reduction of quality.

Storage and Shelf Life – Under ideal conditions artichokes will remain fresh and viable for about two to three weeks.

Methods of Cooling Artichokes

Because the temperature at which artichokes are initially cooled and stored is so important, and because their temperature should be lowered quickly for maximum quality preservation, basic room cooling is not ideal. That is because room cooling alone does not cool the artichokes quickly enough and depending on conditions may not ever be sufficient to lower their temperatures to proper levels. Instead the following cooling methods are recommended:

Forced-Air Cooling – Forced-air cooling involves placing the artichokes in a refrigerated room or cooler; however, with the addition of specially designed fans that pull cool air through the artichokes. This dramatically shortens the amount of time it takes to cool them.

Hydrocooling – Hydrocooling involves rapidly lowering the artichokes’ temperature by submerging them in near-freezing water.

Packing Ice – Artichokes can also benefit from the cooling effects of being placed in direct contact with packing ice.

SEMCO/SEMCOLD LLC provides high quality, industrial cooling and storage solutions for maintaining artichoke quality. Our systems can be customized to fit the commercial needs of our customers and to preserve the taste and quality of artichokes. Our goal is to help our customers bring only the best quality, healthiest, and most delicious artichokes to the end consumer.

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Effective Post-Harvest Cooling and Storage of Peppers

It’s no secret that Americans love sampling exotic dishes from other cultures and then making them a dietary staple here at home. As a result peppers, a common ingredient in a variety of Asian and Latin dishes, are finding their way onto more and more American plates. Considering their delicious, zesty, flavorful taste they are a welcome addition. However, for peppers to pack the most nutritional punch, and for them to taste their best, they need to be properly cooled, stored, and handled.

General Facts About Peppers

There are many varieties of peppers, each with its own unique flavor profile. Some common, popular ones include bell peppers, banana peppers, jalapenos, cayenne, pimiento, and chili peppers. Though each of these peppers has its own distinct properties and culinary uses, there is much overlap with regard to proper harvesting, handling, cooling, and storage methods.

General Information About Cooling and Storing Peppers

One important trait that sets peppers apart from many other types of fruits and vegetables is that they do better in mid-range temperatures than many other types of produce. However, this also means that they are very sensitive to damage if temperatures are either too high or too low. Peppers also require careful handling to avoid sustaining physical damage.

Respiration – Like other fruits and vegetables peppers continue to respire after they have been harvested. This respiration in turn releases heat and if left unchecked it will hasten the ripening, color change, and decay of the pepper.

Temperature – Peppers should be stored at temperatures of about 45°F to 50°F. Above 50°F their respiration and degradation rate is much higher and they are subject to shrinkage, softening, and even the development of disease. However, below 40°F the pepper is subject to chill damage in the form of pitting, softening, and more rapid decay. Over-cooling can be just as detrimental to peppers as under-cooling.

Relative Humidity – Peppers require a high relative humidity of about 90% to 95%. Without enough humidity they will suffer water loss and reduced quality.

Handling – Pepper are typically harvested during hot summer months. This results in harvest temperatures that are often upwards of 90°F. Thus it is imperative that peppers be cooled within at least 1-2 hour of harvest. They should also be handled carefully and never left out in the sun or they may suffer from sunscald.

Storage – Peppers often require separate storage from other fruits and vegetables. This is because of both their preference for somewhat higher temperatures than many other fruits and vegetables as well as their sensitivity to ethylene. Ethylene is released naturally by many fruits and vegetables as a byproduct of ripening and it in turn further accelerates ripening. If peppers are exposed to ethylene their shelf life will be dramatically reduced.

Shelf Life – Under optimal conditions peppers can last for up to 2-3 weeks with little loss of quality.

Methods of Cooling Peppers

There are two primary cooling methods for peppers:

Forced-Air Cooling – Forced-air cooling is the preferred cooling method. It involves placing the peppers in a cooler on pallets and pushing chilled air through the pepper containers with the use of a fan. This forced circulation significantly reduces cooling time and helps chill the peppers more quickly and efficiently.

Room Cooling – The other major cooling method for pepper is room cooling. This involves placing the coolers in a chilled room such as a cooler and allowing them to gradually chill to the ambient temperature. However, room cooling is a much slower process than forced-air cooling and depending on the circumstances it may not be a sufficient method by itself.

SEMCO/SEMCOLD LLC understands how important it is to protect harvested peppers with reliable, high-quality cooling and storage methods. We design and build customized cooling systems for our customers which can be perfectly tailored to fit the needs of pepper crops. This in turn results in better prices for sold peppers and improved quality and taste for end consumers.

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The Importance of Properly Cooling Carrots Post-Harvest

Carrots make a delicious, nutritious, low calorie snack. They are also very popular in salads and are frequently found in fruit juices and health drinks. One of the main reasons carrots are so popular is due to their crunchy texture as well as their sweet, satisfying taste. However, for optimal texture, taste, and nutrition it is imperative that carrots be properly cooled and stored after harvest.

General Facts About Carrots

Carrots are closely related to traditional herbs such as parsley, dill, fennel, and cumin which are typically grown for their aromatic leaves and flavorful seeds. Like these other plants, carrots too were originally grown primarily for their leaves and seeds rather than their roots. Overtime carrots were cultivated to improve the taste, texture, and size of their roots, elongating them and giving them a less woody flavor. Nowadays of course carrots are almost exclusively grown and eaten for their roots; however, their leafy greens are still sometimes eaten as well.

Carrots are low in calories and starch and rich in vitamins such as β-carotene, α-carotene, and γ-carotene, which metabolize into vitamin A. Vitamin A is important for eye health. Carrots are also rich in antioxidants and minerals. They are believed to improve blood flow and aid in healthy digestion.

General Information About Cooling and Storing Carrots

Carrots may be stored, transported, and sold as either topped carrots, which have had the greens cut off of them, or as bunched carrots, which retain the greens intact. This distinction is important because bunched carrots have a shorter shelf life than topped carrots.

Temperature – Both topped and bunched carrots should be stored at a temperature of about 32°F. They should also be cooled as soon after harvest as possible and ideally should be harvested in cool soil. However, it is not recommended for the carrots’ temperature to drop below 0°F or freeze damage may occur.

Respiration and Degradation – The extra foliage on bunched carrots results in a dramatically higher rate of respiration and thus also accelerated degradation and loss of quality.

Relative Humidity – Carrots should be stored at a very high relative humidity, about 98% – 100%. This prevents them from losing moisture. If they lose moisture their texture and crunch will be compromised as well as their overall taste and nutritional value.

Handling – Carrots should be handled carefully to avoid bruising their shafts or damage to their tips. Damaged spots act as weak spots for decay and rapid degradation to set in.

Ethylene Exposure – Like many fruits and vegetables carrots will change in the presence of ethylene. For carrots ethylene exposure will result in a more bitter, less pleasant taste. For this reason carrots should be kept separate from other produce that release ethylene as they ripen.

Shelf Life – Topped carrots will last up to a very impressive 9 months under optimal conditions. By contrast bunched carrots will only last approximately 2 weeks under optimal conditions.

Methods of Cooling Carrots

Because it is important to cool carrots quickly and thoroughly and keep them at low temperatures, basic room cooling alone is seldom optimal. Instead the following methods are recommended:

Forced-Air Cooling – Forced-air cooling, which utilizes specially designed fans to pull cool past the carrots, results in much faster cooling times.

Hydrocooling – Hydrocooling involves submerging the carrots in near-freezing water and is very effective at rapidly cooling the carrots. Hydrocooling also helps prevent the carrots from becoming dehydrated.

Packing Ice – Packing ice directly on the carrots is another highly effective means of cooling the carrots. This approach will also help with rehydration if the carrots are somewhat dehydrated.

SEMCO/SEMCOLD LLC is proud to offer a wide range of industrial cooling systems that are ideal for use to cool carrots. Our systems can be customized to fit the capacity and cooling method needed for each client’s operations. We will work closely with you to ensure that the system is optimal for your carrots or other produce.

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Best Practices for Post-Harvest Cooling of Peas and Beans

Peas and beans are one of the most popular types of food in the US. They are often sold fresh, frozen, or canned and they are considered a staple by millions of Americans. However, in order for peas and beans to taste their best and offer the most nutritional value possible it is important that they be properly cooled and stored prior to consumption.

General Facts About Peas and Green Beans

Peas are considered a botanical fruit; however, they are commonly prepared and eaten as a vegetable. Peas are closely related to legumes and beans. Peas form in small pods that can be cracked open to attain the tender fruit. Peas have been consumed by human beings since the beginning of recorded history and as such there are a wide variety of different cultivars. The main ones we will be discussing are southern peas which include crowder peas, cream peas, and black-eyed peas to name just a few.

Like peas, beans are also actually considered a botanical fruit, but also like peas they are commonly prepared and eaten in ways similar to that of a vegetable. The term bean is typically used in reference to members of the leguminosae family. However, the term may also be applied to the seeds or pods of unrelated plants such as castor beans, cocoa beans, coffee beans, or vanilla beans, which simply bear a resemblance to true beans. Like peas, beans have also been consumed throughout recorded history. In this article we will focus primarily on snap beans, also known as green beans, and lima beans, also known as butter beans.

General Information About Cooling and Storing Peas and Beans

Respiration and Degradation – Peas and beans, like most other types of fruits and vegetables release heat as a result of respiration which then contributes to their degradation and loss of quality. Because of this it is important to begin cooling the peas and beans within at least 1-2 hours of harvest. The peas and beans should also not be left in direct sunlight while they are awaiting cooling.

Temperature – Peas and beans do best with a storage temperature of about 37 °F to 45°F. At higher temperatures the rate of respiration is faster which in turn leads to more rapid degradation and loss of quality. However, if the storage temperature drops below 31°F the peas and beans may be subject to freeze damage.

Relative Humidity – Peas and beans thrive at a cooling and storage relative humidity of about 95%.

Handling – To prevent damage and loss of quality it is important that peas and beans be handled carefully during harvest and storage.

Shelf Life – Depending on the storage conditions and the particular peas and beans they will typically have a shelf life of about 5 to 10 days.

Methods of Cooling Peas and Beans

Hydrocooling – An effective method for quickly and thoroughly cooling peas and beans is hydrocooling. This involves submerging the peas and beans in very cold water to rapidly remove heat and prolong shelf life. The water should be as near to freezing as possible while still remaining liquid.

Forced-Air Cooling – Basic room cooling is not a sufficient method of cooling peas and beans because it takes too long and pods located near the center of the container may never cool fully. However, forced-air cooling, which involves pulling cooled air through the peas and beans is about 8 times faster than room cooling alone, depending on the fans and load size, and is a very effective cooling technique.

SEMCO/SEMCOLD LLC is a leader in industrial cooling and freezing equipment. We can custom-build cooling systems designed to customer specs that are ideally suited for cooling peas and beans. Please contact us for more information.

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Methods for Storing and Cooling Onions After Harvest

Onions are one of the most widely used food items in the US. They are an important flavoring component in countless dishes and are even eaten raw on sandwiches and salads. Onions are also rich in antioxidants and flavonoids which may bring a number of healthful benefits including anti-cholesterol, anti-inflammatory, and anti-cancer. For onions to properly serve their crucial culinary and nutrition niche, they must be stored, cooled and transported carefully in ways that take the quality and freshness needs of the onion into consideration.

General Facts About Onions

The phrase onions encompasses a wide array of different bulb vegetables in the Allium genus, including such exotic members as the Egyptian onion (A. ×proliferum), The Japanese bunching onion (A. fistulosum), and the Canada onion (A. canadense) to name just a few. However, most varieties of common onions are in the A. cepa species, including red onions, yellow onions, white onions, shallots, and potato onions, each of which has a different and distinct flavor.

Onions pose a unique challenge to growers because unlike many other fruits and vegetables which can go straight from harvest into cooling and storage, onions need to be dried first. In some regions onions are dried in the field; however, areas with high humidity and rainfall during onion harvesting season must instead dry the onions by other means such as in bins and barns, often with carefully regulated humidity and temperature.

General Information About Cooling and Storing Onions

Like other fruits and vegetables onions have specific cooling needs which include factors such as temperature, humidity, handling, and storage. As discussed above onions also require drying. Depending on the resources available some farmers have had success repurposing equipment and facilities used for drying tobacco, peanuts, and other crops into use for drying onions.

Drying – Drying is crucial to reduce the onion’s susceptibility to decay organisms, extend their shelf life, and vulnerability to bruising. Even dried onions are of course still subject to eventual decay and physical damage, but drying helps provide them with extra time and resistance. Drying times will vary from two or three days if heated air is used, to anywhere upwards of one or more weeks if only ambient air is used.

Humidity – During drying onions should be exposed to a relative humidity of about 65%. Higher humidity levels will lengthen drying times or even prevent full drying. This will also increase the onion’s risk of neck rot and other problems. Once the onions are dried and are in cold storage a slightly higher humidity of about 70% to 75% is generally acceptable.

Temperature – During drying heated air temperature should be 100°F. Higher temperatures should be avoided since anything over 110°F can damage the onion. Once the onion is dried it should be stored in a cooler or cool environment with a temperature between 32°F and 36°F. It is important to prevent the temperature from reaching 31°F or lower because his will subject the onion to freeze damage.

Storage – Temperature and humidity greatly impact how long an onion can viably be stored and at what rate the onion loses mass. Onions stored in temperatures 50°F or higher may be subject to sprouting.

Exposure to Other Produce – Onions should also be kept separate from other fruits and vegetables, both to protect the onion and the other food. That is because onions will readily leach moisture from other produce, drying out the other food and exposing the onion to too much moisture for proper storage. Onions also have a very pungent odor and many other types of produce may absorb the smell.

Cooling Method for Onions

Onions should be cooled using the room cooling method. This involves placing them in a refrigerated room or large walk-in cooler. It is important to continue monitoring temperature and humidity levels while the onions are in the cooler.

Long-Term Storage

Onions can also successfully be placed in controlled atmosphere storage for even longer-term storage. This involves carefully regulating not only temperature and humidity levels, but also the onion’s exposure to gases such as oxygen, nitrogen, and carbon dioxide. Onions in controlled atmosphere storage may last up to 8 months with minimal quality loss.

SEMCO/SEMCOLD LLC offers quality cooling equipment that can be customized and designed to fit the needs of onions. We can also tailor our systems to the particular capacity demands and other requirements of our customers. Please contact us for more information.

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Ice and Cooling Methods for Cabbage and Leafy Greens

Cabbage and leafy greens such as collard greens, mustard greens, turnip greens, and kale are an important source of vitamins and nutrients. They are often discussed together due to similarities among planting, harvesting, and nutrition. However, there are some important differences with regards to the way cabbage should be cooled and stored versus these other greens. Recognizing these differences and employing the best cooling and storage method for each vegetable is crucial for getting the best taste, quality, and market value.

Factors Influencing the Cooling and Storage of Cabbage

Cabbages come in a variety of colors such as green, purple, and white; however, the green variety is of course the most popular and well known. It is closely related to cauliflower, broccoli, and brussels sprouts. It comes in closely packed groups of leaves called heads. A head of cabbage may range from 1 lbs to 9 lbs, depending on variety. Most cabbage varieties grown in the US fall in the range of 3 lbs to 5 lbs when mature.

Temperature – As with just about every fruit and vegetable, temperature is closely tied to shelf life and quality preservation in cabbage. The optimum temperature for cabbage to be stored is 32°F.

Humidity – Cabbage should be kept at a relative humidity of 95%.

Freezing – It is important to avoid subjecting cabbage to freeze damage. Cabbage will freeze at a temperature of 30°F.

Ethylene Gas – Decomposition of cabbage is accelerated when the cabbage is exposed to ethylene gas. Ethylene gas is released by many different types of fruits and vegetables as a byproduct of their own ripening and decomposition. Some such ethylene gas-producing fruits and vegetables include apples, pears, peaches, and tomatoes. Cabbage should be stored and cooled separately from these other foods to prevent this interaction.

Cooling Methods – Cabbage may utilize one of the following cooling methods

  • Room Cooling – The most common way to cool cabbage is by placing it in a refrigerated room such as a large cooler and allowing it to gradually cool to lower ambient temperatures. It will take a typical, medium-sized head of cabbage around 18 hours to cool from 80°F to 36°F.
  • Forced-Air Cooling – Though room cooling is typically sufficient, some people make use of forced-air cooling to accelerate the cooling of cabbage. This involves arranging the containers of cabbage around a fan and using the fan to pull air through the ventilated containers, thereby forcing air circulation and increasing the rate of cooling.

Shelf Life – When properly harvested, handled, cooled, and stored cabbage has a shelf life of about 2 to 3 months.

Factors Influencing the Cooling and Storage of Leafy Greens

The term “leafy greens” is applied to various leaf vegetables such as collard greens, mustard greens, turnip greens, and kale. These greens may be harvested in leaf bunches or by the entire plant. Leafy greens are more perishable than cabbage and have a shorter shelf life.

Temperature – The optimum temperature for cooling and storing leafy greens is about 32°F.

Humidity – Leafy greens should be kept in a humid environment to prevent them from drying out. Their optimum relative humidity is about 95%.

Freezing – Leafy greens are easily damaged by freezing. As with cabbage they will freeze at about 30°F.

Cooling Methods – Leafy greens require faster cooling than cabbage to maintain their best quality. One of the following cooling methods may be employed:

  • Hydrocooling – One of the most successful methods of cooling leafy greens quickly and efficiently is with hydrocooling. This involves submerging the greens in near-freezing water.
  • Packing Ice – Leafy greens may also benefit from being placed in direct contact with packing ice to quickly and efficiently get their temperature down.

SEMCO/SEMCOLD LLC understand the needs of the produce industry and we are eager to go the extra mile to serve our clients with their industrial or commercial cooling needs. We offer a wide range of cooling systems that are ideal for cabbage and leafy greens and which can be customized to fit each client’s different capacity demands and other specifications.

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Methods for Cooling Tomatoes After Harvest

Tomatoes are an extremely popular type of produce that are used in a wide variety of dishes and which may be eaten fresh and raw, turned into paste or sauce, or of course used for America’s favorite condiment: ketchup. However, for optimum taste and quality it is very important that the temperature of tomatoes be closely regulated. What follows is a discussion of general tomato information, factors that affect cooling and storage, and proper cooling methods.

General Facts About Tomatoes

One of the most popular tomato-related debates is whether tomatoes are fruits or vegetables. Botanically they are fruits of the nightshade family, specifically Solanum lycopersicum. In terms of culinary practices they are often used in ways similar to a vegetable. Tomatoes as a food originated in Mexico. However, due to their versatility, taste, and ability to grow in different regions, they quickly spread throughout most of the world following the Spanish colonization of the Americas in the 1500s.

Tomatoes are renowned for their nutritional value. They contain an important and powerful antioxidant known as lycopene. Lycopene has been shown to have a number of health benefits including possible prevention of cancer, particularly prostate cancer, and skin protect against UV rays. There is also research being conducted into whether or not tomatoes have heart-healthy benefits for people with type 2 diabetes and whether or not tomatoes can improve urinary tract function.

General Information About Cooling and Storing Tomatoes

Tomatoes are more complicated to cool and store than many other types of produce because there is a very wide variation of correct storage temperature depending on the ripeness of the tomatoes. Tomatoes also vary in shelf life depending on ripeness at the time of harvest and storage conditions.

Ripeness/Color – Tomatoes are often graded on ripeness based on the color of their skin. The colors and criteria are as follows:

  • Green – Green tomatoes have a surface that is completely green. The particular shade of green may range anywhere from light to dark. Tomatoes are called “mature green” when they have reached the stage of ripening that will allow them to fully ripen into red tomatoes. Immature greens are tomatoes that are not yet mature enough to ripen fully and should be avoided. Mature greens on the other hand will be indistinguishable from vine-ripened tomatoes by the end of the ripening process and come with the added benefit of a longer shelf life.
  • Breakers – Tomatoes are called breakers when their green skin features tannish yellow skin with pink or red spots that do not cover more than 10% of the tomato’s surface.
  • Turning – Tomatoes are said to be turning when they have tannish yellow, pink, or red skin that makes up more than 10% of their surface but less than 30%.
  • Pink – Tomatoes are said to be pink when they have more than 30% but less than 60% of their skin a pinkish red or red color.
  • Light Red – Light red tomatoes have a pinkish red or red skin that comprises more than 60% of their surface but less than 90%.
  • Red – Red tomatoes are those with more than 90% of their surface red.

Temperature – The correct storage temperature for tomatoes varies based on their ripeness/color. As a general rule the more ripe the tomato the cooler its correct storage temperature. Tomatoes stored at temperatures too cold for their ripeness stage will suffer cold damage, reduced taste and quality, and may never fully ripen. By contrast tomatoes stored at temperatures too high for their ripeness stage may be subject to premature spoilage, decay, and damage. Mature greens may be stored at 58°F to 60°F, while pink tomatoes may be stored at 48°F to 50°F. Fully ripe tomatoes may be stored at temperatures as low as 40°F.

Humidity – The correct humidity level for storing and cooling tomatoes is about 85% to 95%, with lower humidity levels running the risk of drying out or dehydrating the tomatoes and higher humidity levels making the tomatoes more susceptible to rapid decay. Some studies suggest an even more narrow range of about 85% to 90% with concerns that even humidity levels over 90% could hasten decay.

Ethylene – Like many other fruits and vegetables tomatoes produce and release ethylene as they ripen, which in turn further hastens the ripening process. Unripe tomatoes may be intentionally treated with ethylene to bring about more rapid ripening prior to being sold to consumers. By contrast unripe tomatoes not yet ready to be sold should avoid contact with ethylene.

Storage – Because tomatoes are sensitive to ethylene it is typically a good idea to keep them separate from other fruits and vegetables since these other types of produce may unintentionally hasten ripening or, likewise, ripe tomatoes may hasten the ripening of other produce. Along the same lines ripe tomatoes may also need to be kept separate from unripe tomatoes. Once a tomato fully ripens its shelf life is much lower.

Shelf Life – The shelf life of tomatoes varies based on their ripeness, as well as the other factors discussed above. Generally mature green tomatoes will have a shelf life of about 21 to 28 days. Pink tomatoes have a shelf life of about 7 to 14 days. Fully ripe red tomatoes only have a shelf life of about 2 to 4 days.

Methods of Cooling Tomatoes

Tomatoes should be cooled using the room storage method, which involves placing the tomatoes in a refrigerated room or cooler set to the correct temperature for the tomato’s given ripeness level. It is important to ensure that the tomato boxes are well ventilated to allow heat to escape and for proper air circulation. Tomatoes should also be handled carefully as they are very prone to physical damage due to bruising, dropping, or general mishandling. SEMCO/SEMCOLD LLC offers industry-leading cooling equipment that can be customized to handle the unique demands and cooling sensitivity of tomatoes.

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Cooling and Storing Methods for Strawberries After Harvest

Strawberries are known the world over for their sweet, succulent flavor, juicy texture, and brilliant red color. They are the ideal dessert after a meal, a perfect afternoon snack, or a great flavoring for pies, jams, jellies, compotes, ice cream, and more. However, for strawberries to live up to their lofty potential they must be handled carefully, cooled quickly and thoroughly, and not allowed to re-warm. What follows is a discussion of strawberry-related information, general facts about cooling and storage, and ideal cooling methods.

General Facts About Strawberries

Strawberries as we know and love them today were first cultivated in the 1750s in Brittany, France by crossing two wild varieties of strawberries: the Virginian strawberry, native of the United States, and the Chilean strawberry, native of Chile and Argentina. The cross proved quite fruitful indeed and resulted in what we now refer to as the garden strawberry or simply strawberry. Despite the name, strawberries are not true berries at all; instead they are aggregate accessory fruit, meaning that the tasty flesh is not from the plant’s ovary itself but rather the adjacent tissue. Other accessory fruits include pineapples, figs, and mulberries.

Strawberries are a common ingredient in countless desserts, preserves, cereal bars, snack products, juices, and other foods and beverages. They are a great source of vitamin C and manganese, and contain small amounts of essential unsaturated fatty acids crucial to a healthy diet. It is believed that strawberries might improve heart health, fight cancer, and help with inflammation, though research on these purported benefits is on going.

General Information About Cooling and Storing

Strawberries are a highly perishable fruit which pose a number of cooling and storage challenges. That is because they are highly sensitive to heat, moisture levels, and mishandling. Even under ideal circumstances they have a fairly limited shelf life. This makes it important to eek out every bit of saleable life span they have by optimizing the way they are cooled and stored. The following are key considerations:

Respiration – Like most other fruits and vegetables, strawberries respire and give off heat as a byproduct of this respiration. Unfortunately respiration rates are directly tied to degradation and over-ripening and these effects are only accelerated at higher temperatures. For comparison a ton of strawberries releases about 3,300 Btu per day at a temperature of 32°F; however, at a temperature of 80°F the same ton of strawberries would release a whopping estimated 41,800 Btu – nearly 13 times as much heat!

Humidity – Strawberries are extremely sensitive to humidity levels. They require a relative humidity in the range of 90% to 95%. If humidity levels are too low the strawberry will shrivel up, losing its taste and quality. On the other hand, if the humidity is too high water and moisture may form on the strawberry which exposes it to decay organisms such as gray mold and rhizopus rot. These pests are extremely communicable and will readily infest an entire container of strawberries from only one small initial source.

Temperature – To reduce respiration and extend strawberry shelf life as much as possible the fruit should be cooled rapidly to about 32°F to 34°F as soon as it is picked, and it is crucial that these temperatures remain constant. If the strawberries are allowed to rewarm they are subject to spoiling. However, the strawberry will freeze at 31°F, which will also damage it.

Handling – Strawberries are delicate and very prone to bruising and physical damage. Once they are damaged the weak spot becomes a site vulnerable to decay organisms and rapid spoiling. This makes it essential that strawberries be carefully harvested and packaged and that any damaged fruit be discarded rather than be allowed to remain with the good strawberries and spoil them.

Shelf Life – Even when conditions are optimal strawberries only have a shelf life of about 5 to 7 days. This makes it very important for strawberry operations to be as efficient as possible and for strawberry farmers to arrange potential buyers before harvest.

Methods of Cooling Strawberries

Because of the various challenging elements of strawberry cooling, storage, and handling strawberries have a limited number of options in terms of what cooling methods can be employed. Basic room cooling is not suitable because it is essential for strawberries to get their temperature down quickly, within 2 hours or less, after harvest. Room cooling would cool them too gradually. Hydrocooling is not suitable either because the water and moisture would make them more susceptible to threats from decay organisms like gray mold. Slush ice and packing ice would risk physical damage. That leaves strawberries with one viable cooling method: forced-air cooling.

Forced-Air Cooling – Forced-air cooling involves arranging the strawberries around a fan and pulling, rather than blowing, air through the containers. This thus forces cool air circulation and cools the strawberries much more quickly than non-forced air methods would allow. Once again because of the strawberries’ sensitivity to humidity levels it is important to monitor air moisture and ensure that the process doesn’t dry the strawberries out or allow condensation to form on them.

SEMCO/SEMCOLD LLC understands the unique challenges associated with strawberry cooling and storage. Our forced-air cooling systems are versatile and can be custom designed to fit each client’s particular capacity and scale demands.

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Methods for Cooling Sweet Corn After Harvest

Corn, also known as “maize” in many parts of the world, is one of the most popular and widespread crops on the planet. The United States produces about 332 million metric tons every year. There are two major types of corn: field corn, which is used as a starch-rich variety used in corn products such as cornmeal, corn oil, and other corn-based foods; and sweet corn, which is a sugar-rich variety which is eaten as a vegetable and prized for its taste. For sweet corn to be flavorful and high quality it must be rapidly and continually cooled otherwise the sugars will begin converting into starches.

General Information About Cooling and Storing Corn

Sweet corn is an extremely perishable crop which requires immediate and consistent cooling until it reaches end consumers. If it is not properly cooled it will rapidly become tough and starchy, losing its tenderness and sweetness and no longer being suitable for consumption. There are several important cooling factors which affect sweet corn.

Respiration and Degradation – Like many other types of fruits and vegetables a major source of quality loss for sweet corn is due to the rise in temperature caused by natural cellular respiration. The respiration rate is heavily dependant on temperature, making it crucial to quickly and thoroughly cool sweet corn to preserve its quality. The respiration rate at 90°F is a staggering eight times higher than at 32°F. Considering that field temperatures are often upwards of 90°F when sweet corn is harvested this can lead to almost immediate degradation if left unchecked.

One remedy to limit respiration is to harvest the sweet corn in the early morning, while temperatures are lower and while the moisture content is highest. This also helps reduce cooling loads for subsequent cooling and helps save energy. Another common method is to immediately begin covering the sweet corn with cool well water as soon as it is harvested.

Moisture Retention – Moisture retention is another important factor in sweet corn quality. To best retain moisture the sweet corn should be neatly and uniformly trimmed to remove long shanks and flag leaves. Loss of moisture can result in kernel denting as well as a loss of quality and taste. Once again treating the corn with cool water can help with moisture retention.

Sugar Content – Sweet corn has a high percentage of sugar which gives it its characteristic sweet, flavorful taste. However, almost as soon as it has been harvested the sugars present begin converting into starches. This process cannot be completely stopped, but it can be significantly slowed, preserving the quality and value of the corn for longer. Temperature is an important factor with the loss of sugar being about four times as rapid at 50°F as it is at 32°F. Once the sugars are converted into starches this process cannot be undone. That makes it crucial that the corn remain properly refrigerated for its entire journey from harvest into the eventual hands of the consumer.

Relative Humidity – The relative humidity of the environment plays an important role in moisture retention and proper cooling. Sweet corn does best with a relative humidity of about 90% to 98%.

Storage – Storage times will vary but under ideal storage conditions, those with low temperature and high humidity, sweet corn can be stored for around 5 to 8 days without a major loss in quality. Some newer, supersweet varieties are able to be stored for even longer.

Methods of Cooling Corn

Basic cooling methods such as room cooling, which involves placing the sweet corn in a refrigerated room or cooler, are not adequate to cool the sweet corn rapidly and efficiently enough. Instead hydrocooling and packing ice is recommended.

Hydrocooling – Hydrocooling involves rapidly cooling the corn by submerging it in near-freezing water. This is one of the most effective ways to quickly and efficiently remove the majority of field heat and help the corn quickly approach suitable cooling and storage temperatures. However, hydrocooling is most efficient when the temperature differential between the corn and the water is high. In other words when water temperatures are low, such as with freezing water, and when corn temperatures are high, such as with freshly harvested crops. After about 20 to 30 minutes of hydrocooling the temperature of the corn will have decreased by about 20 degrees or more. As a result the next 20 degree temperature drop would take twice as long as the first 20 degree drop and would require over an hour of additional hydrocooling.

Packing Ice – Because hydrocooling becomes less efficient the lower the temperature of sweet corn gets, it is recommended that after initial hydrocooling the remaining necessary temperature drop be attained through the use of packing ice over and around the sweet corn. This will help save energy and lower cooling loads. A good rule of thumb is to use about one pound of ice for every five pounds of sweet corn.

SEMCO/SEMCOLD LLC offers high quality hydrocooling and icing systems that are ideal for use on sweet corn cooling. Our systems and product lines can be customized to suit the capacity needs and other specifications of each our clients.

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