Effect of hydrocolloid addition on dough microstructure
Fig.2 (a)-(e) represented the comparison of dough microstructure from those of WF and RF
controls and 1.5%-hydrocolloid-added samples. Only dough microstructure of FF samples
with 1.5% hydrocolloids were shown because their hardness and toughness were closer to
WF. It was visible in all samples (Fig.2a-2d) except RF (Fig. 2e) that starch granules were
embedded in the matrix. In WF or positive control, the starch granules clearly appeared to be
wrapped by protein matrix (Fig. 2d), which corresponded to its being the highest puffiness
shown in table 1. This is because gluten, as an essential structure-building protein, contributes
to qualities of bakery products [1, 4, 8]. As for rice flour crackers (RF), starch granules were
seen but dough structure was indistinguishable (Fig. 2e) due to the fact that rice flour is
widely known as lacking gluten. Therefore, dough structural formulation is primarily due to
starch gelatinization which ultimately results in many large pores in dough [7] and final
product with brittle structure and cracks on product surface [2, 7]. This complied with the
noticeably dry surface appearance and cracks in RF control illustrated in Fig. 1 (a) although
pores in rice dough in this study were not as clearly visible as shown by [7] due to the
limitation of an instrument.