Abstract:
The natural colorants used in the production of Thai desserts, particularly green
coloring from pandan leaves, are mostly unstable. The primary green pigment in
pandan leaves is chlorophyll. During heat processing, chlorophyll transforms into
brownish-green pheophytin, which negatively impacts the appearance of food
products. Additionally, acidic conditions can cause the replacement of Mg2+ in
chlorophyll with H+, leading to the formation of brown pheophorbide. This research
aims to optimize conditions for producing Lodchong Singapore noodles mixed with
green extract from pandan leaves, focusing on minimizing color changes. Additionally,
optimal drying temperatures were studied to extend the shelf life of the product. The
study investigated the effects of varying concentrations of cassava starch gel mixed
with pandan juice extracted with lime water (30%, 35%, and 40% w/v) on the
production of Lodchong Singapore. The results showed that samples containing 30%
cassava starch were the greenest. The green color diminished as the tapioca starch
content increased, with statistical significance (p≤0.05). The study then explored the
impact of using different concentrations of sodium hydrogen carbonate (NaHCO3)
solution to extract green color from pandan leaves. Concentrations tested ranged from
0.00% to 1.00% (w/v). The samples using 0.00% NaHCO3 showed the lowest green
color, while those with 0.25% NaHCO3 had the brightest green color. Higher NaHCO3
concentrations resulted in decreased green color, along with higher tensile strength
and elasticity (p≤0.05). The optimal formula, containing 0.25% NaHCO3, was used in
the study of drying instant Lodchong Singapore at 50°C, 60°C, and 70°C. A drying
temperature of 70°C reduced drying time and yielded the most intense green color.
Lower drying temperatures (p≤0.05) led to a reduction in green color. Drying at 70°C
also resulted in the best shape recovery rate and texture, which was appreciated by
taste testers. These findings provide insights for producing food products containing
green coloring from pandan leaves or other green plant sources, offering guidelines for
future research and applications.