Impact of Harvest Maturity and Controlled Atmosphere on Strawberry Quality Under Simulated Export Conditions

Abstract

This study aimed to evaluate the effects of controlled atmosphere (CA) treatment on the postharvest quality of strawberries harvested at different 50% and 80% maturity under export shipping conditions. The strawberries were subjected to CA and refrigerated container (Reefer) environments at 10 °C, and their quality attributes were then analyzed. Metabolomic profiling revealed significant variations in primary and secondary metabolites and volatile organic compounds (VOCs). A pathway analysis revealed that CA conditions altered metabolic pathways related to sugar, amino acid, and energy metabolism during storage. CA treatment effectively delayed the accumulation of anthocyanins and enhanced the levels of specific amino acids and VOCs essential for the flavor and aroma of strawberries. Bioluminescence imaging revealed that CA treatment effectively reduced lipid peroxidation. A correlation analysis showed that certain VOCs and secondary metabolites significantly correlated with lipid peroxidation, indicating their role in enhancing antioxidant activity and reducing oxidative stress. These results suggest that CA conditions are associated with significantly reduced weight loss, the maintenance of firmness, and lower respiration rates in strawberries, particularly in those harvested at 80% maturity, extending the shelf life and improving the sensory quality of strawberries. Therefore, CA treatment is an effective method for long-term export.

Keywords: VOCs; decay; firmness; lipid peroxidation; metabolite profiling; respiration.

Figure 1

Comparison of the effect of controlled atmosphere (CA; 5% O₂ + 12% CO₂) and Reefer (air) container treatments on weight loss (a), firmness (b), respiration rate (c), and decay rate (d) of strawberries. The strawberries were harvested (0 D) at different maturity stages (50 and 80%), containerized for 7 days (7 D) at 4 °C, and subjected to cold distribution for 7 days (7 D/1 d, 7 D/3 d, and 7 D/7 d) at 10 °C. Data are expressed as means ± standard deviations. Different letters indicate statistically significant differences.

Figure 2

Comparison of the effect of controlled atmosphere (CA; 5% O₂ + 12% CO₂) and Reefer (air) container treatments on skin color index (CIE L* (a), CIE a* (b), hue angle (c), and chroma (d)) of strawberries. The strawberries were harvested (0 D) at different maturity stages (50 and 80%), containerized for 7 days (7 D) at 4 °C, and then subjected to cold distribution for 7 days (7 D/1 d, 7 D/3 d, and 7 D/7 d) at 10 °C. Data are presented as means ± standard deviations. Different letters indicate statistically significant differences.

Figure 3

(a) PLS-DA score plot of strawberry metabolites at different maturity stages under the CA and Reefer during simulated export; (b) strawberries at 50% maturity; (c) strawberries at 80% maturity; (d) strawberries under the CA condition. Symbols indicate maturity stages (circle, 50% maturity; box, 80% maturity), export methods (open symbols, Reeder; filled symbols, CA), and export periods (gray, 0 D; black, 7 D; blue, 7 D/3 d; red, 7 D/7 d).

Figure 4

Metabolomic pathways of primary metabolites of strawberry according to the effect of controlled atmosphere (CA; 5% O₂ + 12% CO₂) and Reefer (air) container treatments. The strawberries were harvested (0 D) at different maturity stages (50 and 80%), containerized for 7 days (7 D) at 4 °C, and then subjected to cold distribution for 7 days (7 D/1 d, 7 D/3 d, and 7 D/7 d) at 10 °C. The y-axis represents relative abundance, calculated as normalized chromatogram intensity over internal standard intensity, while the x-axis indicates storage duration. * Amino acids were quantitatively analyzed with authentic standards. Data are expressed as means ± standard deviations. Different letters indicate statistically significant differences.

Figure 5

Metabolomic pathways of secondary metabolites of strawberry according to the effect of controlled atmosphere (CA; 5% O₂ + 12% CO₂) and Reefer (air) container treatments. The strawberries were harvested (0 D) at different maturity stages (50 and 80%), containerized for 7 days (7 D) at 4 °C, and then subjected to cold distribution for 7 days (7 D/1 d, 7 D/3 d, and 7 D/7 d) at 10 °C. The y-axis represents relative abundance, calculated as normalized chromatogram intensity over internal standard intensity, while the x-axis indicates storage duration. Data are expressed as means ± standard deviations. Different letters indicate statistically significant differences.

Figure 6

Metabolomic pathways of volatile organic compounds (VOCs) of strawberry according to the effect of controlled atmosphere (CA; 5% O₂ + 12% CO₂) and Reefer (air) container treatments. The strawberries were harvested (0 D) at different maturity stages (50 and 80%), containerized for 7 days (7 D) at 4 °C, and subjected to cold distribution for 7 days (7 D/1 d, 7 D/3 d, and 7 D/7 d) at 10 °C. The y-axis represents relative abundance, calculated as normalized chromatogram intensity over internal standard intensity, while the x-axis indicates storage duration. * Amino acids were quantitatively analyzed with authentic standards. Data are expressed as means ± standard deviations. Different letters indicate statistically significant differences.

Figure 7

Comparison of the effect of controlled atmosphere (CA; 5% O₂ + 12% CO₂) and Reefer (air) container treatments on the intensity (a) and total flux (b) of bioluminescence emitted by strawberries. The strawberries were harvested (0 D) at different maturity stages (50 and 80%), containerized for 7 days (7 D) at 4 °C, and subjected to cold distribution for 7 days (7 D/1 d, 7 D/3 d, and 7 D/7 d) at 10 °C. Images were taken using a charge-coupled device camera-equipped In vivo Imaging System and analyzed using the Living image 4.7.2 software that associated a pseudo color scale to the emitted photon and assigned quantified (cps) values to the detected photon intensities shown on the right side of images. Data are expressed as means ± standard deviations. * p < 0.05, and ** p < 0.01 (n = 8).