Abstract: To improve product quality, this study used ‘Innovator’ potatoes to investigate the effects of three refrigeration treatments: refrigeration at 4 ℃ (control), delayed cooling (7 d at room temperature followed by storage at 4 ℃), variable temperature treatment (7 d at room temperature, 7 d at 4 ℃, then 7 d at room temperature followed by storage at 4 ℃) on the physicochemical properties and quality indices of fresh-cut, quick-frozen, and deep-fat fried potato sticks. The results showed that the freezing and frying processes reduced the L* value, reducing sugar content, hardness and crispness, while advancing the T21 relaxation time of potato sticks. Compared with the control group, both delayed cooling and variable temperature treatment significantly (P < 0.05) increased the L* value of fried potato sticks. After 120 d of storage, the L* value of fried potato sticks was 15.50% and 29.97% higher in the delayed cooling and variable temperature groups than in the control group, respectively. Furthermore, both delayed cooling and variable temperature treatment decreased the reducing sugar and acrylamide contents of fried potato sticks, the latter being more effective than the former. After 120 d of storage, the reducing sugar content and acrylamide content were 30.98% and 6.89% lower in the variable temperature group than in the control group, respectively. However, the effect of variable temperature treatment on the hardness and crispness of fried potato sticks was not significant, and its impacts on chewiness, springiness, and water status depended on the treatment method and storage time. Correlation analysis showed that the negative correlation of L* value with reducing sugars and total phenols, the positive correlation of a* value with reducing sugars and total phenols, the positive correlation of reducing sugars with acrylamide and total phenols, and the positive correlation between crispness and T21 were improved in the variable temperature treatment group compared with the control group. This study showed that delayed cooling and variable temperature treatment significantly improved the processing quality of potatoes, with variable temperature treatment showing a more pronounced effect. These findings provide valuable insights for optimizing storage conditions in practical potato processing.

Key words: potato sticks; storage conditions; temperature changes; reducing sugar; total phenols