| Summary: | 碩士 === 國立臺灣大學 === 食品科技研究所 === 87 === The effects of the protein content (8.80-14.30%), the emulsifier [sodium stearoyl-2-lactylate (SSL), sucrose stearic acid ester (SSE) and monoglyceride (MG)] ,and cooling time (0 min, 120 min, 240 min) during the process on the eating qualities and texture of Chinese vermicelli were investigated.
The results indicated that the mixing tolerance of dough increased with the increase of protein content by Farinograph. However, inverse relations were found with pasting peak viscosity on the pasting profile by Rapid Visco Analyser, and G''max from dynamic rheological measurements.
Both the firmness and tensile strength of Chinese vermicelli were raised significantly with the increment of protein content. Steam-treated samples had higher firmness and tensile strength than non-steam-treated ones. The addition of SSL increased the firmness and tensile strength; but SSE and MG, decreased. The firmness and tensile strength with added emulsifier and steam treatment was reduced. However, the different cooling period during process did not affect significantly.
The Hunter L and WI values decreased, and a and b values increased with increasing the protein content, which implied darker color was observed. The addition of 0.5% SSL increased L value; but SSE and MG decreased L value and increased a value. Both L and WI values of Chinese vermicelli raised significantly with the prolonging cooling time, but a and b values reduced.
The optimum cooking time for the Chinese vermicelli increased with the increase of protein content, but the cooking loss and cooked weight gain decreased. Similar effects were also detected with steam treatment. Adding emulsifier and steam treatment reduced optimum cooking time and raised cooking loss. But the effects on cooking weight gain were varied. The cooked weight gain was increased for the sample with SSL added and without steam treatment, and SSE or MG added and steam treatment. The cooling time during the process did not influence significantly on optimum cooking time and cooking loss. However, when the cooling time was prolonged to 120min and beyond, the cooked weight gain was increased profoundly.
Based on sensory evaluation, the degree of darkness and yellow color was in proportion to the protein content. The smoothness of steamed sample decreased significantly than that of without steam treated one. No significant effect on overall acceptability by the protein content was detected.
The denser structure with fewer fissures was observed on the SEM with the increase of protein content. The fissure on the micrograph was broadened for the low protein with steam treatment.
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