Postharvest Cooling is a method that slows down this decaying process and maintains the quality of the produce. Postharvest cooling is important as it ensures that products get to the consumers in the freshest condition possible. We deal with the best quality Hydrocoolers and Vacuum coolers so that you can always spell success with high-quality produce. We at Quik-Cool ensure that the quality of vegetables and fruits are maintained until they reach consumers.
The Quik-Cool engineering and design team work with customers to design postharvest cooling solutions for all types of local produce. As soon as vegetables, crops and fruits are harvested, their tissues begin to die.
Hydro cooling is the process of showering fresh produce with ice-cold water to rapidly cool fresh produce and assist in increasing shelf life.
To deliver the highest quality product to consumers, Hydrocooling is one of the prime postharvest cooling methods used by harvesters. The purpose of hydro cooling is to decline the decaying process and elongates harvests’ shelf-life.
In Hydrocooling, fruits and vegetables are rapidly cooled immediately after they are harvested by drenching in running cold water or dipping in a tank of cold water. When it comes to the conduction of heat, water offers greater effectiveness than air. In most hydro cooling systems, pan with holes is used for drenching, so that the water gets equally distributed with less required energy than sparing through nozzles.
Temperature, humidity and natural respiration start affecting the quality of fruits and vegetables immediately after harvesting. Even if the produce is harvested at night, it reacts to oxygen to form water, CO2 and heat that has a detrimental effect on the cells of the product, further decreasing its shelf life. Hydro cooling is one of the postharvest cooling methods that eliminate tissue damage by water treatment. To make the process effective, hydro coolers offer sufficient capacity to pull out the absorbed heat from the produce. Hydro cooling treatments are generally time-consuming as they cool the product thoroughly from the core.
Although Hydrocooling lowers the temperature of products quickly, it solely cannot be used to store fruits and vegetable for long. So, to avoid the spreading of plant and human pathogens or propagation of fungal and bacterial growth, sanitiser is used while recirculating water. Recirculation of water cools the “internal warm air fleshy products” or products with internal space (pumpkins, bell peppers, etc.) and prolongs their shelf life. Hydro cooling keeps the moisture of the harvested products intact and thus, retains freshness for a longer span.
Fruits and vegetables that respond well to the hydro cooling method-
- Green beans
- Brussels sprouts
- Watermelon, etc.
The efficiency of a system depends upon the type and model of the hydro cooler. When properly operated, well-designed hydro coolers can cool a large number of vegetables and fruits in a short span of time.
Vacuum cooling is yet another postharvest cooling methods that involve a reduction of pressure inside a sealed metal chamber which leads to the evaporation of water and causes a cooling effect. This system works best for vegetables and fruits that lose water easily. Known as one of the most energy-efficient procedures for removing heat from products, vacuum cooling is fast and helps to avoid moisture loss.
In this postharvest cooling method, harvested products are placed in a sealed container from which the excess air or heat is pumped out. This system creates a virtual pressure where the air pressure is less than 1 KPa. Under this condition, water is boiled at less than 7°C and the moisture inside vegetables turn into a vapour that causes fast cooling. The vapour produced inside the container is then removed by refrigeration coils that again condense the vapour again into the water.
Vacuum cooling is best suitable for vegetables like lettuces, baby leaf crops, etc., as they allow easy moisture loss and cool products quickly. However, vegetables like carrots, zucchini or potato either have waxy skin or low surface area compared to their volume, thus cannot be cooled effectively following this postharvest cooling method.
Traditionally, it is believed that vacuum cooling reduces 1% of the weight for every 5°C reductions in temperature. However, with the advancement of technology, there are vacuum coolers that spray water over vegetables during the process and hence, do not cause significant moisture loss.
Fruits and vegetables that respond well to the vacuum cooling method-
- Brussel sprouts
Vacuum cleaning is one of the fastest postharvest cooling methods that can reduce the temperature of vegetables from 30°C to 4°C in just 20-40 minutes. It is also an energy-efficient option as no electricity is wasted in the process. As the operation takes place in a sealed environment, no infiltration takes place during the cooling process.
Postharvest Cooling for Australian Conditions
The team at Quik-Cool are continually looking for innovative systems and products to improve their performance of commercial and industrial refrigeration systems and postharvest cooling solutions.
Quik-Cool’s team works with refrigeration service and installation businesses helping them with the design and engineering.