Ultrasound improves the low-sodium salt curing of sea bass: Insights into the effects of ultrasound on texture, microstructure, and flavor characteristics

Abstract

The purpose of this study was to evaluate the effects of ultrasonic pretreatment on the quality of cured sea bass. Compared to static marination, ultrasonication significantly increased the rate of NaCl transfer, reduced the hardness and chewiness of fish, and improved water retention. Microstructural observations revealed that the sea bass muscle fibers were severely fragmented, with their borders becoming increasingly blurred with increasing ultrasonic intensity. In addition, ultrasound-assisted marination significantly increased the degradation of proteins, total free amino acid levels, and relative levels of volatile flavor substances such as aldehydes and esters. Therefore, the use of an appropriate ultrasound treatment for the salt curing of fish has a positive effect on the textural and flavor characteristics of sea bass, with the most optimal approach being 300.W ultrasound treatment for 60 min. Overall, the results of this study provide technical evidence for improving the quality of lightly cured low-salt content seafood.

Keywords: Flavor; Low-salt curing; Microstructure; Sea bass; Ultrasound-assisted curing.

Fig. 1

Sodium chloride content (A) and product yield (B) ^A-C Different letters indicate significant differences in ultrasound intensity (P < 0.05).^a-c Different letters indicate significant differences in time (P < 0.05).

Fig. 2

Color change after different curing treatments. Lightness (A), redness (B), and yellowness (C). ^A-C Different letters indicate significant differences in ultrasound intensity (P < 0.05).^a-c Different letters indicate significant differences in time (P < 0.05).

Fig. 3

Textural changes during the curing process. Adhesiveness (A), hardness (B), springiness (C), and chewiness (D).^A-C Different letters indicate significant differences in ultrasound intensity (P < 0.05).^a-c Different letters indicate significant differences in time (P < 0.05).

Fig. 4

Scanning electron microscopy (SEM) images of fish after different curing treatments. S-30 (A), S-60 (B), S-90 (C), UL100-30 (D), UL100-60 (E), UL100-90 (F), UL300-30 (G), UL300-60 (H), UL300-90 (I), UL500-30 (J), UL500-60 (K), and UL500-90 (L). The magnification of A-L is 100×.

Fig. 5

Radar plots of sensory properties of fish with static marination and 300 W ultrasonic treatment.

Fig. 6

(a)–(w) indicate changes in the content of 23 free amino acids (FAAs) under different treatments. Asp (A), Glu (B), Ser (C), Gln (D), Gly (E), Thr (F), Ala (G), Hyp (H), Pro (I), Arg (J), His (K), Tyr (L), Cys (M), Val (N), Met (O), Phe (P), Ile (Q), Leu (R), Lys (S), Cit (T), Nva (U), Sar (V), and Asn (W).^A-C Different letters indicate significant differences in ultrasound intensity (P < 0.05).^a-d Different letters indicate significant differences in time (P < 0.05).

Fig. 7

Heat map of 67 volatile organic compound (VOC) clustering (A), changes in VOC content in fish under different curing treatments (B), changes in VOC quantities in fish under different curing treatments (C).

Fig. 8

Partial least squares discriminant analysis (PLS-DA) of volatile organic compound (VOC) data. Plot of PLS-DA scores for 30 min curing (A), plot of PLS-DA scores for 60 min curing (B), plot of PLS-DA scores for 90 min curing (C), and the total PLS-DA score plot (D). Variable importance in projection (VIP) score plot of curing for 30 min (E), VIP score plot of curing for 60 min (F), VIP score plot of curing for 90 min (G), and the total VIP score plot (H).