Changes of the Aroma Composition and Other Quality Traits of Blueberry 'Garden Blue' during the Cold Storage and Subsequent Shelf Life

Abstract

The changes of volatile composition and other quality traits of blueberry during postharvest storage were investigated. Blueberries were packaged in vented clam-shell containers, and stored at 0 °C for 0, 15 and 60 days, followed by storage at room temperature (25 °C) for up to 8 days for quality evaluation. The firmness, pH, and total soluble solids increased by 8.42%, 8.92% and 42.9%, respectively, after 60 days of storage at 0 °C. Titratable acidity decreased 18.1% after 60 days of storage at 0 °C. The volatile change was monitored using headspace-solid-phase microextraction-gas chromatography-quadrupole time-of-flight-mass spectrometry (HS-SPME-TOF-MS) and off-odor was evaluated by sensory panel. Volatile compounds generally showed a downward trend during cold storage. However, the subsequent shelf life was the most remarkable period of volatile change, and was represented by the strong fluctuation of ethyl acetate and the rapid decrease of terpenoids. Extending storage from 15 to 60 days under cold condition still resulted in an acceptable odor. However, subsequent storage at higher temperature resulted in a quick deterioration in sensory acceptability. The results proved that cold storage was a reliable way to maintain the quality of blueberry, and flavor deterioration during subsequent shelf life was more fatal to the blueberry flavor.

Keywords: aroma compounds; firmness; off-odor; postharvest storage; rabbiteye blueberry.

Figure 1

Berry weight loss during 25 °C storage period after different 0 °C storage lengths. Different letters indicate statistically significant difference (Tukey’s HSD, p < 0.05) between samples.

Figure 2

Decay index during 25 °C storage periods after (a) no cold storage, (b) 15 days of 0 °C storage and (c) 60 days of 0 °C storage. Different letters indicate statistically significant difference (Tukey HSD, p < 0.05) between samples. n.s. No statistically significant difference between samples. Decay index was calculated as follows: no decay = 1; decay berries < 5% = 2; decay berries < 10% = 3; decay berries < 20% = 4; decay berries > 20% = 5.

Figure 3

The changes of key aroma compounds in blueberry during 25 °C storage period after different lengths of 0 °C storage. Volatile concentrations are presented as µg/kg fresh weight (FW). Different letters indicate statistically significant difference (Tukey HSD, p < 0.05) between samples. The dashed line indicates the odor threshold (OT, μg/L in water) of the compound. The odor thresholds (μg/L in water) were obtained from [29]. Odor descriptions for each compound can be found in Table S2 (Supplementary Materials).

Figure 4

Sensory evaluation of off-flavor. 0 + 0: the blueberries prior to storage; 0 + 4: after storage at 25 °C for 4 days; 15 + 0: after storage at 0 °C for 15 days; 15 + 4: after storage at 0 °C for 15 days and subsequent storage at 25 °C for 4 days; 60 + 0: after storage at 0 °C for 60 days; 60 + 4: after storage at 0 °C for 60 days and subsequent storage at 25 °C for 4 days. Different letters indicate statistically significant difference (Tukey’s HSD, p < 0.05) between samples.