Assessment of cumulative freezing frequency of supercooled fresh-cut onion: Effects of sample size, supercooling temperature, and supercooled storage time

Abstract

Recent studies have shown that the supercooled storage of fresh-cut vegetables can extend their shelf-life in the food cold chain, but the effects of cumulative freezing frequency during supercooling have not yet been investigated. Here, we used fresh-cut onions in either a small size sample (SSS) (0.5 g) or a big size sample (BSS) (10.0 g), supercooled at −4, −6, −8, or −10 °C, and investigated the cumulative freezing frequencies from time-temperature profiles using a T-type thermocouple. The results indicated that the cumulative freezing frequency of SSS and BSS from the supercooling tests increased with decreasing supercooling storage temperature and supercooled storage time. The Kaplan-Meier plot with the log-rank test showed that the cumulative freezing frequency of SSS was significantly lower than that of BSS at every supercooling storage temperature. Our research provides useful information on the appropriate supercooling of fresh-cut vegetables that is required for improving their shelf-life without the risk of freezing injury.

Keywords

• Fresh-cut onion
• Size
• Supercooling
• Cumulative freezing frequency
• Log-rank test