Substitution of wheat flour with highly enzyme-resisted cassava starch and its effect on starch digestibility and quality of breads

Possible interaction between pectin and gluten alters the starch digestibility and texture of wheat bread

This study incorporated citrus pectin in wheat bread, aiming to develop breads with both desirable texture and slow starch digestibility. Results showed that starch digestibility in wheat bread decreased over the addition of pectin, and the maximum starch digested amount decreased by 6.6 % after the addition of 12 % pectin (wheat flour weight basis). The addition of pectin transferred part of the rapidly digestible starch into slowly digestible starch, and reduced the binding rate constant between slowly digestible starch and digestive enzymes, resulting in overall reduced starch digestibility. Furthermore, the addition of 4 % pectin contributed to the development of wheat bread with softer texture and increased specific volume. Mechanistically, the lowered starch digestibility of wheat bread after the pectin addition was due to (1) residual outermost swollen layer of starch granules, (2) protein and pectin interactions, and (3) increased short-range ordering of starch. This study, therefore, suggests that the addition of an appropriate amount of citrus pectin has the potential to develop bread with both a low glycemic index and desirable texture.

Preparation of Resistant Starch Types III + V with Moderate Amylopullulanase and Its Effects on Bread Properties

The potential of PulY103A (a moderate amylopullulanase originating from Bacillus megaterium) for resistant starch production under moderate conditions (40 °C; a pH of 6.5) was investigated. PulY103A was much more suitable for pea resistant starch production with a high growth rate of 3.63. The pea resistant starch (PSpa) produced with PulY103A had lower levels of swelling power and solubility and a better level of thermostability than native pea starch (PSn) and autoclaved PS (PSa). The starch crystallinity pattern was B + V, which indicated that the PSpa belonged to RS types III + V. In addition, PSpa was used for breadmaking. The results showed that the bread quality was not significantly influenced compared to the control group when the content of PSpa was under 10% (p > 0.05). The bread supplemented with 10% PSpa had a significantly increased TDF content compared to that of the control (p < 0.05). Moreover, the in vitro mineral bioavailability of the bread sample was influenced gently compared to other dietary fibers, and the bread sample changed from a high-glycemic-index (GI) food to a medium-GI food corresponding to white bread at the same concentration of PSpa. These results indicated that PSpa is a good candidate for the production of dietary foods.