As an attempt to develop a value-added food product, purple sweet potato powder was added in a model system of steamed bread as a healthy food ingredient and physicochemical properties such as moisture content, specific volume, spread ratio, color, texture as well as consumer preferences on the attributes such as uniformity, color, flavor, elasticity, chewiness, taste, and overall preference were evaluated. Moisture content ranged from 44.16 to 44.55% (wet basis) and appeared independent on the level of purple sweet potato (PSP) powder incorporation. As a result of the addition of PSP powder, the specific volume of steamed bread decreased from 3.22 to 2.55 mL/g, and value of 4.5% sample was significantly lower than other samples (p<0.05). On the other hand, spread ratio ranged from 2.01 to 2.53, and appeared to decrease as the PSP powder concentration increased (p<0.05), indicating a significant improvement. Lightness (L*) decreased significantly as the PSP powder content increased (p<0.05) for both dough and skin of the steamed bread. In addition, an increasing trend in redness (a*-value) and a decreasing trend in yellowness (b*-value) were noticed. Firmness increased significantly with the addition of PSP powder regardless of concentration (p <0.05); however, firmness was not significantly different among samples containing 1.5-4.5% PSP powder (p>0.05). Consumer acceptance test indicated that incorporation of 3% PSP powder in the formulation of steamed breads would be recommended.

Background : The hyphal growth of Poria cocos are known to grow well under medium temperature(25 - 28 ℃) and acidic(pH 4.0 - 5.0) conditions. Also, it is known that a large difference in the yield of Poria cocos depending on the cultivation method and environment. Therefore, this research was carried out to secure stable yield of Poria cocos using plastic house and bed soil. Methods and Results : The inoculation time was in mid-April 2016 and the inoculation amount was 3/4 lb each in pine trees of 60 (L) × 10 (D) ㎝. The inoculated wood was buried directly in the bed by soil composition and growth characteristics investigated after cultivating in plastic house from April to September, 2016. The composition of the bed soil was 6 treatments using peatmoss, cocopeat and perlite. The combination ratio ranges of peatmoss, cocopeat and perlite were 0 to 80 %, 0 to 60 % and 20 to 60 %, respectively. We assumed that the combination ratio of peatmoss (organic material) 60 % : perlite(inorganic material) 40% is good for the growth of the Poria cocos. In this ratio, instead of peatmoss, the amount of cocopeat was replaced by 20, 40, and 60 %, respectively. The pH and EC range of bed soil was 4.8 - 5.6, 0.7 - 2.2 dS/m, respectively. pH and EC tended to be lower in treatments with only peat moss and perlite. On the other hand pH and EC tended to raise with increasing cocopeat content. Volumetric soil water content and soil temperature were in the range of 13 - 28 % and 20 - 29℃, respectively, during the period of July to September. Soil water content tended to be higher with increasing cocopeat and peatmoss content and soil temperature tended to be lower. The degree of initial hyphal development and sclerotia formation were good in all treatments compared to the control. However, the number of sclerotia was 6 times higher in the ② treatment than in the control. The size of sclerotia was also the best at 12 (L) × 8 (W) ㎝ in the ② treatment. Conclusion : As a result of cultivating Poria cocos in plastic house, growth characteristics were different according to composition of bed soil. The first reason for this result is that the difference of soil moisture content depending on organic matter content affected the soil temperature. Actually, the average soil water content and soil temperature of ① treatment (organic material 80% ) showed 24% and 22℃ respectively during July to September, and no sclerotia was formed. However, in the ② treatment(organic material 60%), the average soil moisture and soil temperature were 14% and 26℃ during July to September, respectively and sclerotia formation was good. Another reason is that the pH of the bed soil affects the formation of sclerotia. Overall, the degree of hyphal development was good in low pH treatments, but no significant difference was found between the pH and the formation of sclerotia.