Modified atmospheric CO$_2$ levels for maintenance of fruit weight and nutritional quality upon long-term storage in blueberry (Vaccinium corymbosum L.) \u27Liberty\u27

Blueberry fruits have gained consumer attention in recent years due to their good taste and high nutritional value. However, the short shelf-life of the fruit is one of the main downsides in intensive blueberry production. Therefore, optimized storage technology with a modified atmosphere is necessary to prolong blueberry fruit quality on the market. The aim of this study was to investigate long-term storage of fruit of the highbush blueberry (Vaccinium corymbosum L.) ‘Liberty’ under the air control (0.5% CO$_2$, 19.5% O$_2$, 80% N$_2$) and controlled atmosphere conditions of: 5% CO$_2$, 5% O$_2$, 90% N$_2$15% CO$_2$, 5% O$_2$, 80% N$_2$and 25% CO$_2$, 5% O$_2$, 70% N$_2$. Fruit sampling was performed four times during storage (17, 30, 44, 62 days). Evaluation was carried out for fruit weight, total and individual sugar and organic acid contents, sugar-to-organic acid ratio, and individual phenolics contents. After 44 days of storage, weight loss was highest with 15% CO$_2$ and lowest with 5% CO$_2$, with minor variations. The greatest breakdown of total sugars was seen for the air control, and the least for 25% CO$_2$. Organic acids were significantly reduced under all of these storage conditions. Consequently, a high sugar-to-organic acid ratio was maintained in fruit stored with 25% CO$_2$. The contents of all of the identified phenolics significantly decreased with 15% and 25% CO$_2$. After 62 days of storage with 5% CO$_2$, there were small decreases in flavan-3-ols and hydroxycinnamic acids, while flavonoid and anthocyanin contents were unchanged, or for some individual phenolics, content increased. These data show that 15% CO$_2$ or higher accelerates degradation of the phenolics. We can conclude that for maintenance of weight and nutritional quality of the blueberry fruit ‘Liberty’, the optimal controlled atmosphere under long-term storage is 5% CO$_2$, 5% O$_2$, and 90% N$_2$