Yeast cryoinjury in frozen dough: A review on ice crystal-induced hierarchical classification of multi-pathway damage and targeted defense mechanisms.

Yeast survival rate is a key limiting factor for the quality stability of frozen dough. Ice crystal formation and growth act as the primary cause of yeast cryoinjury under freezing stress. They impair yeast cells through three interconnected pathways, including mechanical disruption, osmotic imbalance, and oxidative stress, thereby weakening cell vitality and fermentation capacity. This review proposes a novel cryoinjury hierarchy model. It clarifies that the three damage pathways do not function in parallel but exhibit dynamically dominant roles under varying freezing conditions. In low-sugar systems, mechanical disruption dominates and couples with osmotic imbalance. In high-sugar systems, the damage hierarchy is reversed. Osmotic stress serves as the primary trigger, accompanied by ice crystal mechanical damage and ethanol-mediated oxidative stress. Meanwhile, this review summarizes targeted defense systems against diverse freezing injuries. Core mechanisms involve physical protection, osmotic and protein homeostasis regulation, and oxidative stress balance. A systematic condition-damage-defense theoretical framework is established. It provides solid theoretical references for exploring yeast cryoinjury mechanisms and optimizing the quality stability of frozen dough.