Effect of ultrasonic pretreatment with synergistic microbial fermentation on tenderness and flavor of air-dried duck under low nitrite process

Abstract

The tenderness and flavor of meat products are critical factors influencing consumers' purchasing decisions. This study investigated the effects of ultrasonic pretreatment with synergistic microbial strain fermentation on tenderness and flavor of air-dried duck under low nitrite process. The results demonstrated that ultrasonic pretreatment combined with microbial strain fermentation improved water retention and tenderness of duck meat by disrupting the muscle microstructure, increasing muscle fiber spacing, and facilitating water migration and distribution. This primarily concerns the cavitation and mechanical effects of ultrasound and the role of lactic acid bacteria and yeasts in muscle protein hydrolysis. A total of 34 and 55 volatile flavor compounds were detected by HS-SPME-GC-MS and GC-IMS, respectively. The results indicated that acetaldehyde (stimulating, fruity, green apple), ethyl acetate (sweet, fruity, pineapple), and 3-hydroxy-2-butanone (sweet, creamy) were responsible for the improved flavor during this process, which was primarily related to the increased activity of neutral lipase (0.38 U/g protein), acidic lipase (0.48 U/g protein), and phospholipase (0.09 U/g protein). This study provides valuable insights into the synergistic effects of ultrasonic pretreatment and microbial co-fermentation, offering a theoretical basis for optimizing air-dried duck production and enhancing flavor quality.

Keywords: Air-dried duck; Flavor; Lactic acid bacteria; Tenderness; Ultrasonic pretreatment.

Graphical abstract

Fig. 1

Migration and distribution of moisture and microstructure in air-dried duck meat under different treatments. Moisture content (A); water activity (B); T2 relaxation spectra (C); relative peak area percentages for different water states (D); magnetic resonance images (E); scanning electron microscope images (magnification 200×) (F). Data are expressed as mean ± standard deviation. Different letters (a-e) indicate statistically significant differences (p < 0.05). CK: untreated; US: ultrasonication (250 W, 4 min, 30 °C, 40 kHz); L: inoculation with L. fermentum CGMCC 1.7434; D: inoculation with D. hansenii GDMCC 2.149; LD: inoculation with L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149; US-LD: inoculation with L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149 after ultrasonic pretreatment (250 W, 4 min, 30 °C, 40 kHz).

Fig. 2

Lipase activity and flavor of air-dried duck meat under different treatments. Neutral lipase (A); acidic lipase (B); phospholipase (C). Radar plots of E-nose response data (D); E-nose principal component analysis score plots (E); GC–MS principal component analysis score plots (F); volatile flavor substances heat map (G). Data are expressed as mean ± standard deviation. Different letters (a-f) indicate statistically significant differences (p < 0.05). CK: untreated; US: ultrasonication (250 W, 4 min, 30 °C, 40 kHz); L: inoculation with L. fermentum CGMCC 1.7434; D: inoculation with D. hansenii GDMCC 2.149; LD: inoculation with L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149; US-LD: inoculation with L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149 after ultrasonic pretreatment (250 W, 4 min, 30 °C, 40 kHz).

Fig. 3

GC-IMS analysis of air-dried duck meat under different treatments. Plot of principal component analysis scores (A); 3D topography (B); difference spectrum (C); fingerprinting (D). CK: untreated; US: ultrasonication (250 W, 4 min, 30 °C, 40 kHz); L: inoculation with L. fermentum CGMCC 1.7434; D: inoculation with D. hansenii GDMCC 2.149; LD: inoculation with L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149; US-LD: inoculation with L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149 after ultrasonic pretreatment (250 W, 4 min, 30 °C, 40 kHz).

Fig. 4

Combined analysis of volatile flavor substances by GC–MS and GC-IMS. Wayne diagram of volatile flavor substances (A); bar chart of volatile flavor substance types (B); PLS-DA score plot based on GC–MS (C); VIP score plot based on GC–MS (D); PLS-DA score plot based on GC-IMS (E); VIP score plot based on GC-IMS (F). CK: untreated; US: ultrasonication (250 W, 4 min, 30 °C, 40 kHz); L: inoculation with L. fermentum CGMCC 1.7434; D: inoculation with D. hansenii GDMCC 2.149; LD: inoculation with L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149; US-LD: inoculation with L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149 after ultrasonic pretreatment (250 W, 4 min, 30 °C, 40 kHz).