Potential effects of calcium and ethanol generator pads on mulberry fruit during cold storage

Abstract

The unique flavour and high nutritional value of mulberry (Morus spp.) fruit have increased its fresh consumption in recent years. However, the fruit sensitive to postharvest pathogens, spoil quickly resulted with high level of postharvest losses because of soft and sensitive texture of this fruit with high water content. This study aimed to extend the shelf life of fresh mulberries using ethanol generator pads (EGP) and calcium chloride (CaCl₂) treatments in ‘Bursa Siyahı’ and ‘Kenmochi’ mulberry genotypes. After harvest, the fruits were treated with EGP, 1% CaCl₂ or a combination of both and stored at 0 ± 0.5 °C with 85–90% relative humidity for 21 days. Untreated fruits (control group) exhibited intense mould growth by the 9th day, losing commercial value and analyses were not conducted. In contrast, EGP treatments alone extended the shelf life to 18 days for ‘Bursa Siyahı’ and 15 days for ‘Kenmochi’, while the combination of EGP and CaCl₂ provided intermediate results. As the storage period was extended, the rate of decay and weight loss increased in both genotypes. During storage, weight loss in EGP-treated fruits was limited to 2.63%, compared to over 5% in the control group. The total anthocyanin and total phenolic content showed a significant decrease in all treatments during the storage period. However, the EGP treatment was more effective in preserving these parameters. On day 6 of the study, the total anthocyanin content in ‘Kenmochi’ and ‘Bursa Siyahı’ fruits was 764.48 and 10.98 mg/100 g in EGP treatment, while it was 610.60 and 6.83 mg/100 g in the control group, respectively. It was also found that the treatments had no effect on the color change of the mulberries. The combination of cold storage and EGP effectively extended the storage period of the fruits. These findings highlight the potential of EGP as a practical, cost-effective solution for the fresh fruit market. Furthermore, besides the treatments, storage time and temperature are the determining factors in fruit quality. However, its impact on mould growth became limited after a certain period. Our results show that, regardless of the treatments applied, storage time also has a significant effect on fruit quality.