Frozen food: New thawing methods will improve safety and quality

Frozen meals help maintain kitchen efficiency by keeping food safe for extended periods. However, the thawing process can change the quality of food in subtle ways.

A new study took a close look at emerging solutions that can keep frozen meals safe and appetizing. The study was led by Dr. Gülşah Çalışkan Koç from Tekirdağ Namık Kemal University, who studied a range of thawing methods for frozen foods.

Understanding the impact of freezing

Freezing adds shelf life by slowing chemical activity and restricting the growth of microorganisms (organisms too small to be seen by the human eye). This means that frozen items stay edible for longer.

However, large crystals often form when food is frozen slowly. These can puncture cell structures and cause issues like flavor changes or a mushy texture.

In contrast, smaller ice crystals typically form when food freezes rapidly, and this tends to reduce the internal damage to the food.

Faster thawing to maintain freshness

Cold air thawing in the refrigerator is simple and works well when safety is a top concern. Yet this method can take over a day for bigger cuts to defrost, which can be frustrating in busy kitchens.

Still-water thawing tends to be a little faster. However, nutrients can leak out into the water, and in some cases the outer surface warms long before the interior.

There is an ongoing need for methods to speed up the thawing process while maintaining freshness. Reduced thawing times help minimize the risk of microbial growth.

Researchers are exploring ways to improve methods for evenly distributing heat into foods, preserving their flavors and textures. This includes innovative techniques such as high-pressure treatments, radio waves, and pulsed electric field systems, which apply high-voltage pulses between two electrodes.

Thawing methods for frozen foods

High-pressure thawing keeps the temperature low while altering ice’s melting point. This cuts time and may limit nutrient losses, though it demands specialized machinery.

Radio frequency thawing uses electromagnetic fields. It heats food from inside out, which can shorten thaw times for large blocks.

Microwave thawing is convenient, but it sometimes creates hot spots on the edges or surfaces. Manufacturers recommend rotating and adjusting power to even out the heat when defrosting items using microwaves.

Ohmic thawing pushes alternating current through the item to generate heat, and that can be more uniform than microwaves. Maintaining consistent contact between electrodes and the product helps reduce the chance that certain spots remain partially frozen.

Ultrasound and electrostatic field

Ultrasound-based thawing relies on acoustic waves to disrupt the boundary between frozen and thawed layers. Work with certain fruit and meat items shows faster thawing with this method, and produces lower drip loss than standard water immersion.

High-voltage electrostatic field thawing moves ions through the air and around the product to enhance convective heat exchange. The main advantage of this method is speed and reduced water loss.

Balancing costs, safety, and food quality

Equipment costs vary widely. Microwave ovens are common, but they may not suit large-scale thawing unless properly set up.

Systems like radio frequency or high-voltage setups often cost more to acquire and maintain. Even so, food producers report fewer losses, shorter thaw times, and improved final quality.

Food processors can now choose from a menu of standard and modern thawing methods. Certain high-volume firms may prefer multi-step processes that use a quick method first, then finish with a more gentle method.

Balancing cost, speed, safety, and product appeal is a constant challenge. Each approach has pros and cons, and the choice usually hinges on budget, equipment space, and the type of food.

Rapid thawing maintains safer conditions because the food spends less time in the temperature danger zone. Less moisture loss means the product holds onto nutrients and flavor compounds.

Some technologies still need fine-tuning to tackle the problem of uneven heat distribution. But these innovations are shaping a more effective approach to thawing in both household and commercial settings.

Fast meals that taste good

Researchers point to combination approaches as a promising way forward. Hybridizing sound waves, pressure, or electric fields may ease common snags, like burned surfaces or soggy textures.

Emerging methods are appearing in labs and pilot plants with encouraging results. Researchers remain focused on ways to keep foods fresh while shaving hours off production timelines.

Consumers want meals that cook fast but taste good. Novel thawing is helping meet that demand by minimizing nutrient losses, saving energy, and improving safety.

Creative solutions remain a top interest, especially for items such as meat, seafood, and dough products.

The study was published in Comprehensive Reviews in Food Science and Food Safety.

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