Objective: Apples are rich in nutrients such as carbohydrates, organic acids, cellulose, vitamins, minerals, polyphenols, and flavonoids, earning them the title of "all-around healthy fruit" by scientists. However, after harvesting, apples are prone to aging and decay due to their own respiration and metabolism, water loss, and microbial contamination, leading to a decline in fruit quality and nutrient content. To investigate the relationship between storage conditions, storage time, and nutritional content, we conducted a follow-up monitoring study.
Methodology: A batch of Red Fuji apples purchased from a fruit shop was divided into two groups and stored separately in a refrigerator (4°C) and at room temperature (average 18°C). Over a 60-day period, the apples' appearance was observed, and their weight loss rate, reducing sugar, titratable acidity, vitamin C content, and nitrite content were measured to compare the differences under the two storage temperatures.
Results: Under room temperature conditions, significant changes in the nutritional content of the apples were observed between 7 and 15 days. By day 15, the peels began to shrivel and the texture became soft. By day 30, brown spots appeared on the flesh. The weight loss rate increased significantly after 7 days, and by day 15, the loss of vitamin C reached 50%, with a marked increase in nitrite content. In contrast, the refrigerated apples did not show significant changes until day 30. For instance, softening was not observed until day 30, and skin wrinkling did not appear until day 60, with a vitamin C loss of 30%.
Furthermore, over the same storage period, the refrigerated apples showed significantly lower rates of weight loss, increases in nitrite content, and decreases in vitamin C content compared to those stored at room temperature. This may be because at room temperature, the apple's respiration consumes its own water and nutrients, and the onset of decay leads to an increase in nitrite levels. In contrast, during cold storage, the apple's respiration rate slows down and ethylene release is reduced, thereby consuming less of its own nutrients and moisture and experiencing decay at a later stage compared to room temperature storage.
Recommendation: The recommended storage period for apples at room temperature is within 15 days, and for refrigerated storage, it is within 30 days. If you purchase a large quantity that cannot be consumed in the short term, it is best to store them in the refrigerator.