Chemical and physical characteristics of wheat flours and sweet potato tubers
Imported wheat flour had slightly higher moisture content (12.82%) than that of
domestic wheat flour (11.28%) (Table 1) that can be due to different packaging and storage
conditions. Meanwhile, domestic wheat flour showed much higher ash content (1.38% dw)
relative to imported flour (0.65% dw) (Table 1). High ash content, which represents total
mineral content of the flour, may give dark colour of the noodle produced [25].
Protein content of domestic wheat flour (13.83% dw) was relatively higher than that of
imported flour (11.66% dw) (Table 1), particularly due to genetic factor (cultivar). However,
this value was slightly lower than protein content presented in the description of Dewata
variety (15.66% dw at m.c. 11%) [7] that might be due to differences in planting season and
crop environment conditions. Wheat flour predominantly consists of gluten that is formed
from glutenin and gliadin proteins when mixed with water. Gluten plays an important role in
dictating noodle elasticity and texture [25]. Wheat flour with protein content of 10-13% is
suitable for noodle ingredient [31]. The whiteness level of domestic wheat flour was
considerably lower than that of imported wheat flour (Table 1). This may due to dark colour
of the seed bran (genetic factor) that could be partly involved in the flour after polishing and
milling process.
Beta 1 variety contained high beta carotene content (Table 2) that was showed by
deep orange colour of the root flesh. Simonne et al. [32] revealed that beta carotene content
of sweet potato positively correlated with orange flesh intensity (r = 0.99). The deep orange
colour of the flesh tuber can be also seen through the relatively low lightness (L*) value
(Table 2). Ameny and Wilson [33] and Ginting et al. [16] (2008) noted that L* value showed
negative correlation with beta carotene content with r = -0.74 and r = -0.91, respectively.
Erliana Ginting and Rahmi Yulifi anti / Procedia Food Science 3 ( 2015 ) 289 – 302 293
Beta 1 variety also had relatively high moisture (> 73.5%) and reducing sugar contents
(> 6.8% dw), but considerably low starch content (< 20% fw) (Table 2) according to
Antarlina’s criteria [34]. Orange-fleshed sweet potato tended to have high moisture and low
dry matter contents [15], moist and sweet taste when steamed [14, 16]