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.

In vitro evaluation of probiotic properties of Lactobacillus acidophilus AD125 and antagonism against Escherichia coli O157:H7 adhesion to Caco-2 cell.

This study investigated the in vitro antibacterial activity of Lactobacillus acidophilus AD125 against Escherichia coli (E. coli) O157:H7 and its probiotic properties: gastrointestinal tolerance, surface hydrophobicity, autoaggregation, coaggregation, and adhesion to Caco-2 cells. In addition, the action mode of the strain's antagonism against adhesion of E. coli O157:H7 to Caco-2 cells was analyzed, and related substances were also determined. Results showed that L. acidophilus AD125 had stronger antibacterial activity (inhibition zone of 20.47 ± 0.43 for AD125 culture solution and 14.55 ± 1.12 for cell-free supernatant) against E. coli O157:H7 than other Lactobacillus spp. Also, this strain had higher gastrointestinal tolerance, autoaggregation percentage (26.51 ± 0.71%), and coaggregation percentage (23.97 ± 0.44%) with E. coli O157:H7. High surface hydrophobicity of toluene and xylene (83.59 ± 2.54% and 93.45 ± 1.24%) was also observed. Bacterial adhesion counts were 1176.54 100 per cells, indicating good adhesion to Caco-2 cells. Furthermore, the exclusion, competition, and antibacterial effect of AD125 may have driven its antagonism against E. coli O157:H7 adhesion. Finally, surface-layer proteins, extracellular polysaccharides, and thermosensitive substances all participated in the antagonism against E. coli O157:H7, with surface-layer proteins the main related substances. These results show that Lactobacillus acidophilus AD125 is promising for inhibiting E. coli O157:H7 and preventing and treating intestinal diseases induced by E. coli O157:H7.