Comparative Analysis of Texture Characteristics, Sensory Properties, and Volatile Components in Four Types of Marinated Tofu

Abstract

In this study, three different brands of commercially available marinated tofu were analyzed and compared with homemade products to explore the effect of key flavor substances on their sensory quality, sensory properties, texture characteristics, and volatile components. The texture characteristics and flavor substances of the three brands of commercially available marinated tofu were significantly different from those of homemade products. A total of 64 volatile components were identified by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), mainly including 11 hydrocarbons, 11 alcohols, 10 ketones, 15 aldehydes, 4 esters, 1 acid, and 12 other volatile substances. Among these, nine key flavor compounds (ROAV > 1, VIP > 1) were identified using the relative odor activity value (ROAV) combined with a partial least squares discriminant analysis (PLS-DA) and variable importance in projection, including α-Pinene, β-Myrcene, α-Phellandrene, 1-Penten-3-one, Butanal, 3-Methyl butanal, acetic acid ethyl ester, 1,8-Cineol, and 2-Pentyl furan. The correlation heatmap showed that sensory evaluation was positively correlated with hardness, gumminess, chewiness, and springiness while negatively correlated with 2-Pentyl furan, α-Pinene, resilience, α-Phellandrene, 1-Penten-3-one, acetic acid ethyl ester, and 1,8-Cineol. Overall, this study provides a theoretical reference for developing new instant marinated tofu snacks.

Keywords: HS-GC-IMS; PLS-DA; ROAV; key volatile flavor substance; marinated tofu.

Figure 1

Process flow chart of TF4.

Figure 2

Two-dimensional GC-IMS spectrum of the samples.

Figure 3

GC-IMS spectrum of the samples (difference diagram). Note: 1. The background of the spectrum is blue; the vertical coordinate represents the gas chromatographic retention time(s), and the horizontal coordinate represents the relative ion migration time. 2. The color represents the concentration of the substance; white means the concentration is low, and red means the concentration is high; the deeper the color, the greater the concentration.

Figure 4

Gallery plot diagram of the samples of marinated tofu from different brands. Note: Each row represents all signal peaks selected in a sample, and every column represents the difference in signal peaks of the same substance in different samples; the darker the color, the higher the substance concentration and the stronger the signal peak.

Figure 5

Species diagram of the volatile compounds of marinated tofu from different brands.

Figure 6

Relative content of the volatile compounds of marinated tofu from different brands. Different lowercase letters denote a significant difference (p < 0.05).

Figure 7

Venn diagram of volatile compounds with a ROAV ≥ 1 of marinated tofu from different brands.

Figure 8

Scattering conditions of the PLS-DA score of the volatile compounds of marinated tofu from different brands.

Figure 9

Permutation test of the volatile compounds of marinated tofu from different brands.

Figure 10

VIP value of the volatile flavor substances.

Figure 11

Pearson’s correlation heatmap displays the correlation between texture, volatile substances, and sensory evaluation of marinated tofu from different brands. Note: Each color represents the correlation coefficient, with blue and red indicating negative and positive correlations, respectively.