Comparison of immersion freezing, osmo-dehydrofreezing and air freezing on freezing parameters and physicochemical properties of mango (Mangifera indica L.)

Effects of immersion freezing (IF), osmo-dehydrofreezing (ODF) and air freezing (AF) on freezing parameters and physicochemical properties of frozen mango were studied. Results showed that IF had the shortest freezing time, followed by ODF and AF. In ODF groups, dehydrofreezing in 50% glucose (G-50) showed the highest quality. Mangoes pre-treated in glucose had higher quality than those pre-treated in trehalose. The quality of osmo-dehydrofrozen mangoes was more affected by freezing rate than by difference between freezing temperature and the glass transition temperature (T-Tg '). Compared with the AF, IF in 60% ethylene glycol (EG-60) and ODF in G-50 significantly improved the quality of mangoes, including colour change and drip loss reduced by 43.7%, 28.6%, 41.4% and 19.6%, hardness increased by 540.7% and 413.6%, and contents of vitamin C and total phenol increased by 30.7%, 24.3%, 18.3% and 6.4%, respectively. Overall, IF in EG-60 was the most favourable method for frozen mangoes.