Enhancing tenderness and flavor of microwave-dried shrimp through ultrasonic-assisted papain pretreatment: Effects and mechanisms

Shrimp drying extends shelf life and develops unique flavors, but often causes excessive toughness, impairing palatability and digestibility. Enhancing the tenderness of low-moisture dried shrimp facilitated chewing and digestion for individuals with reduced masticatory function. However, research on effective strategies and underlying mechanisms to enhance dried shrimp tenderness remains limited, with single-method approaches demonstrating only modest improvements. This study investigated the effects of ultrasound-assisted papain pretreatment (UAP) on textural, flavor, and taste of microwave-dried shrimp. Results showed that UAP significantly improved tenderness while imparting uniform properties. During microwave heating, both papain and ultrasound promoted the conversion of glycine and serine into pyrazines and ketones. Correlation analysis indicated that UAP unfolded tertiary protein structures, increased total sulfhydryl and surface hydrophobicity, and shifted secondary protein structures towards flexible disorder. Furthermore, UAP accelerated protein degradation, manifesting macroscopically as reduced shear resistance, while expediting final flavor formation.