Soybean protein isolate‐rice starch interactions during the simulated gluten‐free rice bread making process

Effects of soy protein isolate interaction with brown rice starch on the multiscale structure of brown rice bread

BACKGROUND

Gluten-free bread (GFB) has technical bottlenecks such as hard texture, rough taste and low nutrition in practical production. In order to solve these problems, this study used germinated brown rice starch as the main raw material, and investigated the effects of soybean isolate protein (SPI) on the multiscale structure of germinated brown rice starch and bread quality.

RESULTS

A gluten-free rice bread process simulation system was established, and the interaction between SPI and starch in the simulation system was characterized. The result shows that the interaction forces between SPI and germinated brown rice starch were mainly represented by hydrogen bonds, and with the addition of SPI, the crystallinity of starch showed a downward trend. At the same time, when the amount of SPI was 3%, the appearance quality was the best and the specific volume of bread was 1.08 mL g-1. When the amount of SPI was 6%, the texture quality was the best. Compared with the bread without SPI, the hardness of the bread with 6% SPI was reduced by 0.13 times, the springiness was increased by 0.03 times, the color was the most vibrant, the L* value being 1.02 times the original, and the baking loss was reduced to 0.98 times the original.

CONCLUSIONS

The interaction force between SPI and germinated brown rice starch and its effect on bread quality were clarified, and these results inform choices about providing a theoretical basis for the subsequent development of higher-quality GFB. © 2024 Society of Chemical Industry.

High freeze-thaw stability of Pickering emulsion stabilized by SPI-maltose particles and its effect on frozen dough

Pickering emulsions with good freeze-thaw stability are essential in frozen food applications. This study developed a high freeze-thaw stabilized soy protein isolate (SPI)-maltose (M) Pickering emulsion and applied it to frozen doughs to investigate and reveal its impacts on the processing properties of the frozen dough. The results showed that after the freeze-thaw cycle, with a volume ratio of 1:2 of SPI to M, the appropriate amount of M changed the structure of SPI. This resulted in the Pickering emulsion prepared by the SPI exhibiting the least droplet coalescence and the best freeze-thaw stability. The results of dough rheological properties, textural properties, and binding capacity with water demonstrated that Pickering emulsions effectively inhibited the loss of gluten protein network structure in the dough after freeze treatment and increased the binding capacity of gluten proteins with starch and water in the dough. The best results were obtained with the incorporation of 3 % SPI-M high freeze-thaw stability, where the amount of bound water following three freeze-thaw cycles was 4.27 times higher than in doughs without Pickering emulsion. Overall, this study is significant for enhancing the freeze-thaw stability of Pickering emulsions stabilized by proteins and providing a new application route for Pickering emulsions.

The impact of addition of pearl millet starch-germ complex in white bread on nutritional, textural, structural, and glycaemic response: Single blinded randomized controlled trial in healthy and pre-diabetic participants

The rise of pre-diabetes at the global level has created a significant interest in developing low glycaemic index food products. The pearl millet is a cheaper source of starch and its germ contains significant amount of protein and fat. The complexing of pearl millet starch and germ by dry heat treatment (PMSGH) resulted an increase in the resistant starch content upto 45.09 % due to formation of amylose-glutelin-linoleic acid complex. The resulting pearl millet starch germ complex was incorporated into wheat bread at 20, 25, and 30 %. The PMSGH incorporated into bread at 30 % reduced the glycaemic index to 52.31. The PMSGH incorporated bread had significantly (p < 0.05)increased in the hardness with a reduction in springiness and cohesiveness. The structural attributes of the 30 % PMSGH incorporated bread revealed a significant (p < 0.05)increase in 1040/1020 cm-1 ratio and relative crystallinity. The consumption of functional bread incorporated with pearl millet starch germ complex reduced blood glucose levels and in vivo glycaemic index in healthy and pre-diabetic participants when compared to white bread. Hence, the study showed that the incorporation of pearl millet starch-germ complex into food products could be a potential new and healthier approach for improving dietary options in pre-diabetes care.

Effect of soy protein isolate on physical properties of quinoa dough and gluten-free bread quality characteristics

BACKGROUND

Quinoa is a good gluten-free resource for food processing, especially bread making, and can improve and prevent the development of complications associated with celiac disease (CD). However, lack of gluten affects quinoa bread quality. Previous research showed that soy protein isolate (SPI) could improve gluten-free bread quality to some extent. Therefore, this study investigated the effects of SPI on the physical properties of quinoa dough and gluten-free bread quality characteristics.

RESULTS

Results showed that, with appropriate SPI substitution, the farinograph properties of quinoa flour significantly improved (P < 0.05). The sample with 8% SPI substitution showed a better development time (DT, 3.30 ± 0.20 min), stability time (ST, 8.80 ± 0.10 min) and softening degree (SD, 8.80 ± 0.10 FU), which were close to those of wheat flour, although more water absorption (WA, 76.40 ± 2.10%) was needed than for wheat flour (66.30 ± 3.10%). The extensograph properties of quinoa flour also significantly improved after 8% SPI substitution (P < 0.05). Furthermore, SPI substitution increased G' moduli of quinoa dough and decreased tan δ to some extent, providing better rheological properties closer to those of wheat dough. SPI substitution also improved the quality and texture of quinoa bread and reduced the gap with wheat bread. When SPI substitution was 8%, the specific volume, hardness and springiness of quinoa bread were 2.29 ± 0.05 mL g^-1 , 1496.47 ± 85.21 g and 0.71 ± 0.03%, respectively.

CONCLUSION

These results suggested that SPI substitution would be an effective way to develop higher-quality gluten-free bread. © 2022 Society of Chemical Industry.