Effect of cooling rate and super-chilling temperature on ice crystal characteristic, cell structure, and physicochemical quality of super-chilled fresh-cut celery

• Published in: International journal of refrigeration Vol. 113; pp. 249 - 255
• Main Authors: Xu, Cong-Cong, Liu, De-Kun, Guo, Chun-Xiao, Wu, Yu-qing
• Format: Journal Article
• Language: English
• Published: Paris Elsevier Ltd 01.05.2020; Elsevier Science Ltd
• Subjects: Celery; Conductivity; Cooling; Cooling effects; Cooling rate; Cristaux de glace; Crystal structure; Crystals; Céleri fraichement coupé; Electrical resistivity; Extrusion; Flavonoids; Freezing; Fresh-cut celery; Ice crystal; Ice crystals; Immersion; Membrane structures; Polyphenols; Quality; Qualité; Scavenging; Studies; Submerging; Super-chilling; Superréfrigération; Vitesse de refroidissement; Vitesse de refroidissement; Ice crystal; Cooling rate; Super-chilling; Quality; Qualité; Céleri fraichement coupé; Immersion; Cristaux de glace; Superréfrigération; Fresh-cut celery
• ISSN: 0140-7007; 1879-2081
• DOI: 10.1016/j.ijrefrig.2020.01.024

The influence of cooling rates (using different immersion temperatures of –35 °C, –45 °C, and –55 °C) and super-chilling temperatures (–1.5 °C and –3.0 °C) on the ice crystal state, cell structure, and physicochemical quality of super-chilled fresh-cut celery was investigated. Results showed that the average freezing temperature of celery was –0.48 ± 0.08 °C. Tissues super-chilled to –1.5 °C at –55 °C presented numerous tiny ice crystals with a uniform distribution outside and inside cells and well-maintained structures. The retention of texture attributes, the contents of total polyphenols, total flavonoids, and soluble solid, and the scavenging ability of DPPH· were significantly (P < 0.05) increased, and drip loss and relative electrical conductivity were significantly (P < 0.05) lowered compared with other super-chilled tissues. The formation of larger and irregular ice crystals and severe deterioration of cell structures (e.g., the fracture of membrane structures and cell walls, cell deformation, collapse, and extrusion) occurring in other tissues could be the direct cause for their decreased quality. These results provided the possibility that super-chilling could be used as a promising technology for celery preservation. The combination of faster cooling rate and optimal temperature would be crucial for a desired quality of super-chilled fresh-cut celery products.