The fruit of the cherry tomato plant is highly perishable, and conventional precooling methods are often slow and non-uniform. This can lead to an intensification of water loss, membrane injury and flavor deterioration to the fruit. Researchers recently evaluated a stepwise precooling protocol combining hydrocooling and forced-air cooling for rapidly and uniformly removing field heat from freshly harvested cherry tomatoes prior to storage at 10 °C. Among the findings was that gas chromatography-mass spectrometry (GC-MS) profiling revealed greater retention of key aldehydes and esters associated with characteristic tomato aroma. A paper based on this study was published in Food Chemistry.
How do sudden temperature changes affect fruit quality during storage?
Most fruits and vegetables are picked while still warm from the field, which speeds up their natural processes and makes them spoil faster during storage and transport. While storing food at low temperatures helps keep it fresh and appealing for longer, cooling it too quickly can sometimes cause stress that damages the produce. Sudden temperature changes can upset the fruit's internal balance and cause harmful molecules to build up, which can damage cell membranes and lead to poorer texture, color, and flavor during storage.
Precooling is an important step after harvesting that quickly cools produce, helping it stay fresh longer and maintain its texture, nutrients, and appearance. Unfortunately, it has been found that relying solely on low-temperature forced-air precooling may accelerate quality deterioration in cold-sensitive produce.
Most studies on precooling have mainly focused on cooling produce faster and checking basic quality, without really asking whether the way the fruit is cooled affects its taste and condition. This has inspired the researchers to look at that question by testing different cooling approaches for cherry tomatoes—while keeping the final temperature and storage the same—to see how they impact freshness, texture, and aroma. The results help show whether adjusting how quickly and in what steps produce is cooled can better preserve quality and flavor.
The researchers found that, compared with single forced-air cooling, stepwise precooling accelerated cooling by 50-70%, reduced weight loss and decay, and alleviated membrane damage, as reflected by lower electrolyte leakage and malondialdehyde content. In addition, it maintained higher levels of antioxidant enzyme activity and key nutritional attributes, including ascorbic acid, total soluble solids, total phenolics, and lycopene. As mentioned earlier, the GC-MS profiling revealed greater retention of key aldehydes and esters associated with characteristic tomato aroma.
"Therefore," wrote the authors of the paper, "stepwise precooling represents an effective and practical strategy to preserve postharvest quality and flavor in cherry tomatoes, providing an optimized method for cold-chain management."
"Ultimately," conclude the authors "our study provides a foundation for mechanism-guided optimization of precooling protocols and early cold-chain handling of flavor-sensitive produce."
Source: LCGC International
