Abstract:
The aim of this study was to optimize the rhizome size and drying temperature to produce
high quality turmeric powder. The turmeric rhizomes were collected from local farm of
Dharan. The rhizomes were cleaned and sorted into primary, secondary and tertiary
rhizomes. Secondary rhizomes were taken for the study and cross section area of 2.434 ±
0.023 cm2 was maintained. Response surface methodology (randomized, design type D optimal with quadratic model) was applied using Design Expert version 13 taking factors as
rhizome size from 1 to 4 cm and drying temperature from 40 to 70°C which generated sixteen
samples. The samples were cut and dried as per the parameters obtained from design expert
till the moisture content reached to 10%. The optimum value of rhizome size and drying
temperature was obtained by the analysis of five response factors i.e. curcumin, oleoresin,
essential oil content, total phenolic content and antioxidant activity. The optimized turmeric
powder was compared with the market sun-dried sample.
The optimum value of rhizome size and drying temperature was obtained to be 2.6 cm
and 55°C with the value of curcumin, essential oil, oleoresin, TPC and antioxidant activity
to be 5.8%, 7.04%, 20.85%, 38.12 mg GAE/ g dry matter and 49.68 %RSA respectively.
The optimized turmeric powder was found to be superior in quality than sun-dried market
sample in terms of all measured bioactive parameters and antioxidant activity. Thicker
rhizome size and lower drying temperature led to the longer drying time which caused the
oxidative degradation of bioactive components. Similarly, very high drying temperature and
thinner rhizome size led to thermal degradation of bioactive components
Description:
A dissertation submitted to the Department of Food Technology, Central Campus of
Technology, Tribhuvan University, in partial fulfillment of the requirements for the
degree of B. Tech. in Food Technology
