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. 2023 Sep 8;8(37):33299-33309.
doi: 10.1021/acsomega.3c02265. eCollection 2023 Sep 19.

Effects of Starch Addition on KGM Sol's Pasting, Rheological Properties, and Gel Texture

Liling Deng  1   2 , Yan Li  1 , Geng Zhong  3 , Wen Lei  3 , Yongbo Peng  2 , Zhaojing Zhu  1
Affiliations

Effects of Starch Addition on KGM Sol's Pasting, Rheological Properties, and Gel Texture

Liling Deng et al. ACS Omega. .

Abstract

Konjac tofu is an irreversible gel formed by removing the acetyl group from konjac glucomannan (KGM) through alkaline heating. This type of food is low in calories, filling, and healthy, making it popular in the market. However, pure konjac tofu has a hard texture and lacks flavor when heated. To improve its taste and appearance, the effects of three varieties of native starch, including corn starch (CS), Canna edulis Ker starch (CKS), and potato starch (PS), on the formation of pasting and rheological properties of the KGM sol were investigated. Konjac tofu samples that incorporated different types and quantities of starch were prepared and analyzed in terms of structure, texture, dehydration, and flavor, with pure konjac tofu serving as a reference. The findings revealed that KGM mixed with a concentration of 4.2% CS, or 0.85% CKS, or 0.85% PS of the total mass produced a gel with the highest viscosity and a steady structure. Texture profile analysis indexes of these combinations were superior to pure KGM, and the konjac-starch tofu had a lamellar network structure. Thus, konjac tofu with the addition of starch has a higher quality texture, lower dehydration, and improved flavor compared to pure KGM gel.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Pasting curves of pure starch and pure KGM sols (a), KGM and K-CS sols (b), KGM and K-CKS sols (c), and KGM and K-PS sols (d).
Figure 2
Figure 2
Static shear curves of KGM and K-CS (a), KGM and K-CKS (b), and KGM and K-PS (c). Flow properties of KGM and its mixtures with various concentrations of starch (d).
Figure 3
Figure 3
G′, G″ (a), and tan δ (b) as functions of frequency for KGM and K-CS gels; G′, G″ (c), and tan δ (d) as functions of frequency for KGM and K-CKS gels; and G′, G″ (e), and tan δ (f) as functions of frequency for KGM and K-PS gels.
Figure 4
Figure 4
SEM images of KGM gels containing CS (K-CS), CKS (K-CKS), and PS (K-PS) (50× magnification on the left, 100× magnification on the right).
Figure 5
Figure 5
Effect of different temperatures on the hardness of gels.
Figure 6
Figure 6
Effects of different starches on syneresis of KGM gels. Note: different lowercase letters in the bar indicate significant differences (p < 0.05).
Figure 7
Figure 7
Effect of starch addition on oil absorption (a) and salt content (b) of konjac tofu. Note: different lowercase letters in the bar indicate significant differences (p < 0.05).
Scheme 1
Scheme 1. Addition of Starch Can Augment the Pasting and Rheological Characteristics of KGM Sol and Also Improve the Gel Texture of Konjac-Starch Tofu
See this image and copyright information in PMC

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