Unlocking the Potential of Fruit Cold Storage: A Comprehensive Guide

Once a crop is harvested, improving its quality is almost impossible—improper handling and storage results in about 10 to 40% of losses in horticultural crops. Appropriate storage conditions including temperature and humidity are required to maintain the quality and extend the shelf-life or storage life. This is where cold storage has emerged as the primary method for extending the shelf-life of fruits. 

This comprehensive guide will dive into the intricacies of fruit cold storage, shedding light on its importance, temperature guidelines, the process, and its impact on fruit quality and business.

Understanding Fruit Cold Storage 

Fruits are living tissues that breathe or respire even after they are harvested. In fact, their physiology and composition change after harvest. They continue to ripen—cellular breakdown and senescence are unavoidable. However, with the right storage conditions, the process can surely be delayed. 

Purpose of Fruit Cold Storage 

Here are some of the benefits of using cold storage for fruits and vegetables. 

• The best possible system/ technology for storing fruits in fresh from
• Delays or reduces the incidence of biotic and abiotic diseases
• Has a positive impact on the produce weakening 
• Reduces the metabolism and delays the senescence of fruits 
• Helps maintain fruit resistance against fungal infections
• Inhibits or delays the growth and enzymatic activity of pathogens 
• Prevents moisture loss from fruit tissues, thus, reducing shriveling and deterioration

Usually, fruits need low temperatures and high relative humidity to slow down respiration and metabolic transpiration rates. This helps in reducing water loss and maintaining food quality and value.  

Different Types of Cold Storage Facilities for Fruits 

There are several types of cold storage facilities used for storing fruits and each one has been designed to meet specific needs. Here are some examples.

• Refrigerated warehouses: These are large-scale facilities used for storing huge quantities of fruits. They are typically used by wholesalers, distributors, and large retail chains.
• Controlled atmosphere storage: In this type of cold storage the levels of oxygen, carbon dioxide, and nitrogen, as well as temperature and humidity are regulated. This helps slow down the ripening process of fruits. It’s often used for apples, pears, and some other fruits.
• Cold storage rooms: These are specially designed rooms to store fruits at low temperatures. They can vary in capacity and dimensions and are used in a variety of settings, from small businesses to large industrial operations. Modular cold rooms are also gaining popularity for small and medium-sized cold storage needs. 
• Refrigerated containers: These are portable cold storage units that are useful in transporting fruits over long distances while regulating the inside temperature. They maintain a constant temperature to keep the fruits fresh during transit.
• Walk-in coolers: These are small to medium-sized cold storage units used in grocery stores, restaurants, and small businesses. They offer a convenient way to store fruits at optimal temperature levels.

Temperature Guidelines for Fruit Cold Storage

Usually, it is recommended that temperate fruit crops be stored at near-freezing temperatures of 0 to 1°C. Whereas fruit crops of tropical or subtropical origin must be kept at higher storage temperatures of 7 to15°C. These conditions are required to avoid any losses due to chilling injury. 

Temperature  

There is no single recommendation for temperature for cold storage of all fruits. Usually, the climate of the area, maturity at the time of harvest, and the season of the harvest are some of the factors in determining the optimum temperature for storage. 

Also, if the storage temperature is too low, there is a risk of freezing and chilling injury. In fact,  too low temperature can be as damaging as too high. Freezing will occur below 32℉ but the occurrence of injury will depend on the commodity or fruit. Freezing injury can lead to loss of rigidity, water soaking, and softening. However, injury can be reduced if the produce is warmed up gradually to optimum storage temperature and is not handled during that thawing period.  

Image source: Tree Fruits

Relative Humidity 

Transpiration rates (water loss) from the produce are determined based on the moisture content in the air or relative humidity. At high relative humidity, the produce is able to maintain weight, flavour, appearance, texture, and quality while reducing the juiciness, wilting, and softening. 

Detailed Breakdown of Temperature Requirements for Different Types of Fruits

Image source: Storage Conditions: Fruits and Vegetables

Classification of fruits and vegetables based on susceptibility to injury below 32℉

Image source: Storage Conditions: Fruits and Vegetables

Ideally, it is advisable to maintain a temperature near 32ºF (0ºC). For fruit varieties that are chilling-sensitive, temperatures should be maintained in the range of 36 to 38ºF (2 to 3ºC). Fans should be operable to maintain air circulation and high humidity levels will reduce water loss and fruit shriveling. 

The Cold Storage Process 

Here is your step-by-step guide on the process of cold storage. 

1. Harvesting: Maintaining the quality of fruits during harvest is crucial. Any damage or dirt can shorten storage life and affect the fruit’s appearance post-storage. It’s important to avoid placing the produce on the ground to prevent dirt pickup and hence, clean baskets or mats should be used for collection. Also, harvesting should be done at the right time for each type of fruit.
2. Handling:  Proper handling helps avoid damage or dirt accumulation. Ideally, produce should be prepared for storage directly in the field and carefully placed in cold storage containers. This approach minimizes handling and potential damage. A quick transition from harvesting to storage is essential, as delays can significantly shorten the storage life of the produce.
   • Preparation: The fruits should be cleaned before storage. It is recommended to use clean water to avoid the spread of fungal spores. Some fruits may require the removal of outer leaves before storage. However, it is better to leave the leaves on to reduce moisture loss and remove them right before sale. 
   • Pre-cooling: This step involves quickly reducing the temperature of the fruits to remove field heat, which can accelerate spoilage and deterioration. Some of the common methods of pre-cooling are room cooling, forced-air cooling, hydro cooling, and vacuum cooling.
   • Cold storage: Optimum temperature and relative humidity levels should be maintained based on the type of fruit. All fruits usually have a critical temperature below which chill damage can occur due to irreversible reactions. 
   • Packing system: A suitable packing system is required for easy and safe loading and unloading of fruits. This could involve stackable crates or a more complex system with racks and trays. The crates should be manageable when full and sturdy enough to bear the weight of stacking. To ensure proper airflow, a two-foot gap should be maintained between the walls and crates, and a three-foot gap between the crates, ceiling, and refrigeration units.
3.  Transportation: Adequate care needs to be taken during transport and distribution. Handling and concomitant damage can be reduced if the produce can be transported in the same crates they were stored in. Additionally, refrigerated containers should be containers for maintaining desired temperatures during transit. 

The Impact of Cold Storage on Fruit Quality and Business

When it comes to fruit quality and business operations, cold storage can make a huge difference. Cold storage helps maintain the value and quality of the produce by preventing ripening and spoilage. This means not only do consumers receive fresh, high-quality produce but also results in reduced wastage. Farmers and businesses can, thus, improve their profitability. 

Additionally, cold storage facilities allow for effective storage and transportation of fruits for the long haul. This means businesses can expand into newer markets and offer their customers a wide variety of fruits around the year. 

Final Words 

Fruit cold storage is a vital part of the food industry and plays a key role in maintaining quality and value, reducing wastage, and improving operations and accessibility. As the consumer demand for high-quality fruits continues to grow, energy-efficient and effective cold storage will continue to dominate the cold chain infrastructure. 

Whether you are a farmer, distributor, or retailer, get in touch with Rinac to meet all your fruit cold storage needs.