Abstract: This study addressed the effect of polysaccharide hydrocolloids on the crust characteristics and oil penetration of fried battered and breaded fish nuggets (BBFNs). Fish pieces were battered with a mixture of wheat starch (WS) and wheat gluten (WG) at a ratio of 11:1 (m/m) added with 0.3% sodium carboxymethyl cellulose (CMC-Na), 0.2% guar gum (GG), or 0.2% xanthan gum (XG), breaded, and fried at 170 ℃ for 40 s followed by 190 ℃ for 30 s. The fluorescence intensity, surface hydrophobicity (H0), sulfydryl and disulfide bond contents, and secondary structure of WG and the crystal structure of WS in the crust were determined, and the oil penetration in the crust was evaluated. Results showed that the H0, fluorescence intensity, disulfide bond content, relative contents of β-sheet and β-turn in the crusts with the three polysaccharide hydrocolloids were greater than those in the control (without the addition of any polysaccharide hydrocolloids), while the free sulfydryl content and the relative contents of α-helix and random coil of WG, and the relative crystallinity of WS were lower than those in the control. The H0, fluorescence intensity, sulfydryl content and relative α-helix content of WG and the relative crystallinity of WS were lowest for the crust with XG, followed by CMC-Na and GG, while an opposite trend was observed for the disulfide bond content and relative β-sheet content. Furthermore, Sudan red staining area was largest for the control, and smallest for fried BBFNs with XG (present only in the crust), followed by CMC-Na and GG. These results indicated that due to their high hydrophilicity and unique structures, the three polysaccharide hydrocolloids can interact with WG to improve the stability of the crust, thereby inhibiting the oil penetration of fried BBFNs.

Key words: battered and breaded fish nuggets; deep-fat frying; polysaccharide hydrocolloids; crust characteristics; oil penetration