Experimental Design Statistical Analysis

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3.3.2.2.9 Sensory Analysis

Sensory analysis was carried out on the best sample. The best sample produced at the lab and commercial dried bamboo shoots purchased in Mae Sai were tested using hedonic rating. Before testing, both samples were soaked into distilled water 25-26 ⁰C at room temperature ± 26 ⁰C for 12 hours and then boiled for an hour. After that, the samples were cut into same shape and size 50 mm x 5mm x 5 mm. Both samples were presented in pairs according to the predetermined order. They were also coded by 3 random numbers. Thirty five untrained panelists Lawless and Heymann 1998 were asked to give preference score of the attributes on a scale from 1 to 5. Criteria for each attribute tested, including color, aroma, taste, texture, and overall, was shown in Table 4. Table 4. Category scales for rating hedonic test Scale Criteria 1 Dislike extremely 2 Dislike moderately 3 Neither like or dislike 4 Like moderately 5 Like extremely

3.3.3 Experimental Design

Experimental design used in this research was completely randomized factorial design with two factors, i.e. drying temperature code: T and concentration of sodium metabisulfite used in blanching solution code: N. There were three levels of the drying temperature, i.e. 50 ⁰C T 1 , 60 ⁰C T 2 , and 70 ⁰C T 3 , while four levels of the concentration of sodium metabisulfite, i.e. 0 N , 0.5 N 1 , 1.0 N 2 , and 1.5 N 3 , thus there were 12 treatment combinations tested in this research. The treatment combinations were shown in Table 5. Each combination had three replicates, thus the plot of experiments used a total of 36 experimental units. 20 Table 5. Treatment combinations Factors N N 1 N 2 N 3 T 1 T 1 N T 1 N 1 T 1 N 2 T 1 N 3 T 2 T 2 N T 2 N 1 T 2 N 2 T 2 N 3 T 3 T 3 N T 3 N 1 T 3 N 2 T 3 N 3 General model of the experimental design as follows: Y = μ + α + β + αβ + ε where: Y ijk = response for treatment of concentration of sodium metabisulfite at level i, drying temperature of at level j, and replicate k μ = average value α i = treatment effect of concentration of sodium metabisulfite at level i β j = treatment effect of drying temperature at level j αβ ij = interaction between drying temperature at level i and concentration of sodium metabisulfite at level j ε ijk = error

3.3.4 Statistical Analysis

SPSS 16.0 was used for data analyses. Effects of drying temperature, concentration of sodium metabisulfite, and their interaction on water activity, color, rehidration ratio, firmness, and total residual sulfites of dried and rehydrated bamboo shoots were analyzed using ANOVA Generalized Linear Model at 95 confidence level and the further test multiple comparison test would also be done using Duncan test at 95 confidence level Meilgaard et al. 2007. Results of sensory evaluation for color, aroma, texture, taste, and overall preference of rehydrated bamboo shoots were analyzed using t-Test: two-sample assuming equal variances at 95 confidence level Meilgaard et al. 2007.

IV. RESULTS AND DISCUSSION