Sansanee Lertphatcharanon. The extraction and application of dietary fiber from by-product of fresh ground turmeric (Curcuma longa Linn). Master's Degree(Nutrition ). Mahidol University. : Mahidol University, 2007.
The extraction and application of dietary fiber from by-product of fresh ground turmeric (Curcuma longa Linn)
Abstract:
Fresh ground turmeric is a by-product of the herbal industry that is usually
discarded as waste. Utilization of fresh ground turmeric was investigated because of its
dietary fiber content. The objectives of this study were 1) to investigate the preparation
method of dietary fiber from fresh ground turmeric by a bleaching and extraction
procedure; 2) to determine the properties and food application of the extracted dietary
fiber. Fresh ground turmeric was bleached with a hydrogen peroxide solution. The
hydrogen peroxide concentration, the duration of bleaching and the temperature and pH
of slurry affected the color of the turmeric fiber obtained. The suitable condition for the
bleaching of the fiber from turmeric was achieved with the use of 14.5 M hydrogen
peroxide at 1:10 (w/v) in normal acid-alkaline condition of slurry (pH 4) at 87º-93ºC for
60-90 min. Although the color of the fiber was satisfactory compared to fresh ground
turmeric, the yield of fiber was very small and the fiber was aggregated in solid clumps.
Thus, only extraction with alcohol was used in the preparation of turmeric fiber. The
yield of turmeric fiber extraction was 19% and the resulting fiber contained 56% dietary
fiber with the major portion being insoluble fiber. Turmeric fiber had a water holding
capacity of 10.71 g/g sample, an oil holding capacity of 3.58 g/g sample and no
emulsifying activity and emulsion stability. Its water activity was 0.26, its moisture
content was 6.28% and its pH was neutral (7.37). The color of the fiber was light yellow.
Application of turmeric fiber in food products was tested in brownies and pork burgers.
Brownies were formulated by partially substituting turmeric fiber for wheat flour at 10,
12.5, 15 and 17.5% by weight to increase the total dietary fiber content. The highest
possible level of substitution was 12.5% according to quality evaluation including
volume, texture and color. The turmeric fiber-added brownies were also accepted by the
sensory test panel with the overall acceptability score between like slightly and like
moderately. The total dietary fiber content per serving of 12.5% turmeric fibersubstituted
brownies was 2.53 g: Hence, the product could be claimed as a good source
of fiber. In pork burgers, turmeric fiber was used to replace minced pork at 1, 3 and 5%
by weight to improve the yield and reduce the shrinkage of the products after frying.
With the substitution of turmeric fiber for pork, there was an increase in the technological
yield of the burgers. The shrinkage in burger thickness was not affected much while the
shrinkage in burger diameter decreased. The hardness of burgers also increased with an
increase in the amount of turmeric fiber. The optimal level of substitution was found to
be 3%. Sensory evaluation showed that the formulated burgers were acceptable by
panelists with the overall acceptability score being like slightly to like moderately. In
conclusion, turmeric fiber exhibited a good potential for application in food products as a
dietary fiber ingredient.