Effects of Different Freezing Methods on the Freezing Characteristics and Quality of Mango Chunks
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Abstract:
The freezing characteristics and quality changes of mango chunks under liquid nitrogen spray freezing (LNF-40~-100 ℃) were investigated, and comparisons were made with those under refrigerator freezing (RF-20 ℃), and normal immersion freezing (IF-20 ℃). The results show that the temperature for the maximum freez concentration of the mango was -17.98 ℃, the exothermic enthalpy ∆H was -236.8 J/g, and the freezing rate (r) was 0.14~1.40 ℃/min. Among them, the r of LNF-100 ℃ increased by 900%~7.63% compared with other groups; the ratio of heat transfer coefficient (d) increased by 4.6 times compared with the RF-20 ℃ group; Compared with the RF-20 ℃ and IF-20 ℃ groups, the total freezing time and the time across the maximum ice crystal formation zone were shortened by 9 042 s and 4 657 s, and 5 475 s and 870 s, respectively; The color of the mango chunks was also close to that of fresh mango; The firmness retention rate was 83.12%; Water loss was 2.75%; More than 90% of the total phenolic content, antioxidant activity and Vc were retained; The content of exopolysaccharide increased by 0.44 mg/g; The total colony counts before and after freezing decreased by 0.84 lg CFU/g; Pearson's correlation analysis revealed the effects of different freezing methods on the quality of mango blocks, ∆E, water loss, total phenolic content, and Vc content can be used as the basis for effective evaluation; Cluster analysis (CA) confirmed that LNF-100 ℃ can significantly reduce the quality deterioration of mango chunks during freezing. This study provides theoretical basis and technical guidance for the development of high-quality frozen mangoes obtained by a highly efficient freezing process.
