Effects of xanthan and guar gums on starch digestibility and texture of rice flour blend bread

Abstract

Background and objectives The effects of adding xanthan and guar gums on starch digestibility and textural properties were examined in rice and wheat flour blend breads. Findings The addition of xanthan gum to the bread formula had a high impact on the staling of the crumb compared with guar gum. The addition of gums suppressed the recovery of the crumb after compression. The extent of starch digestion of the bread crumb was determined by an in vitro method using two types of bread crumb samples, milled samples after freeze‐drying and ground samples after moistening. Starch digestibility of the bread crumb reduced after the addition of gums. Xanthan gum resulted in a more pronounced suppressive effect, which was concentration‐dependent. The addition of xanthan gum at concentrations ≥1% to the bread formula caused a significant decrease in the extent of starch digestion in both the samples. Conclusions The bread crumb containing xanthan gum had a dense structure and formed an agglomeration after grinding, resulting in delayed enzyme penetration into the crumb structure and thus delayed the enzymatic hydrolysis of starch. Significance and novelty Addition of xanthan gum to the formula of rice and wheat flour blend breads significantly retards the starch digestibility of bread crumb.

Effect of Grass Carp Skin Protein Hydrolysates on the Retrogradation Tendency of Gelatinized Rice Starch in the Presence of Non‐Ionic and Ionic Hydrocolloids During Cold Storage

“…According to the results, at each time point from 0 to 14 d, it was observed that the gels incorporated with XT and GG as well as GCSPHs alone exhibited significantly lower values of the hardness than RS gel, indicating that XT, GG or GCSPHs can suppress the retrogradation of RS gel during storage. Our results are in good agreement with the previously reports, showing that the addition of XT, and GG can result in a reduced hardness of RS gels during storage which may be attributed to the difficulty rearrangement between amylose and amylopectin during crystallization due to the changed hydrogen bond in the presence of XT, and GG.…”

“…The presence of GCSPHs in GCSPHs‐XT gel produced a significant decrease due to the XT containing the charges and the strengthened interactions between the hydrophilic amino acid residuals of GCSPHs and water molecules in the RS gel. In addition to those aforementioned explains, the strengths of the intermolecular hydrogen bonds (between XT, amylose, and amylopectin) led to the reducing the firmness which is in agreement with the previous reports . Therefore, this study demonstrated that the GCSPHs exhibited a more pronounced effect on mitigating the retrogradation tendency of rice starch/ionic hydrocolloid (RS/XT) blends.…”

“…Correspondingly, the degree of crystallinity decreased from 16.6% to 2.8% (Table ) after storage at 4 °C 14 d, indicating that GCSPHs in the presence of non‐ionic and ionic hydrocolloids played a synergetic effect on the inhibition of starch retrogradation. In particular, the synergistic effect of combined GCSPHs with XT was the best,which may be attributed to the more interaction and association within the water in the presence of anionic hydrocolloids, like xanthan gum . These results supported the effectiveness of GCSPHs on inhibiting the recrystallization of amylose and/or amylopectin to enable the reduction of retrogradation observed in TPA and DSC.…”

“…The phenomenon of the above‐mentioned can be explained by the fact that, compared with non‐ionic GG, XT belongs to the anionic gum and there is an ionic interaction between the starch molecules. In addition, electrostatic and hydrophobic interactions existing in GCSPHs and starch molecules in the RS/XT‐GCSPHs system was stronger than hydrogen bonds between GG and starch molecules …”

“…Apart from lack of essential amino acids, due to rice starch, rice products suffer from the severe retrogradation during cold storage that seriously affects the quality and shortens their shelf life. To date, blending of rice starch with hydrocolloids that be classified into non‐ionic (guar gum) and ionic (xanthan) hydrocolloids and their combinations, offers a good way to avoid or minimize the side‐effects of starch retrogradation which have been studied extensively. However, enriching the essential amino acids deficient in rice products is not the only aim when adding GCSPHs.…”