The purpose of this study is to widen the usage of Yacon powder, in which the oligo saccharide is higher than that of the starch, as a functional food material, by partly replacing potato starch, which is widely used a thickening material in chinese cooking. To check the functionality the potato starch mixed with yacon powder has been used in the sweet and sour sauce, one of the most favorite chinese food. In this study, the sweet and sour sauce, have been made by various different mixing rate of freeze dried yacon powder with potato starch, then measured its chromatography, pH, viscosity, spreadability and solid content, and also carried out the antioxidant test and sensory test to find out the most preferable mixing rate of yacon powder, so that to find out the most superior thickening material in functionally and preference, differentiated from existing one in its taste and general preference, and graft it with chinese cooking.
According to the analysing result of general components of Yacon, moisture content was 86.58%, crude protein 0.91%, crude fat 0.28%, crude ash 0.36% and carbohydrate 12.06%. The result showed some difference according to the producing area, variety, crop year and growing environment, but little difference from the study result known to public. According to the antioxidant test of DPPH free radical scavenging activity it was 69.6±0.22%, lower than that of acai berry, 77.65%, but nearly two times higher than that of blueberry, 38.65%. Total phenolic compound of yacon was 163.78㎎ CE/100g, 5 times higher than that of acaiberry, 31.69㎎ CE/100g, and nearly 8 times higher than that of blueberry, 21.08㎎ CE/100g.
According to the chromatography test result, L-value, brightness, of reference group was 39.99±0.80, the highest, and getting darker according to increasing the mixing rate of yacon, the lowest was 35.40±0.19 from sample group of yacon 20% mixing. So there was significant difference among sample groups. For a-value, redness, the highest was 4.05±0.06, from sample group of Yacon 15%, and showed a little difference according the change of yacon mixing rate, but there was no significant difference among specimens including reference group. For b-value, yellowness, the highest was 12.14±3.13 from reference group, and getting decreased according to increasing the mixing rate of Yacon, the lowest was 6.71±0.11 from sample group of Yacon 20% mixing. So there was significant difference with reference group, but no significant difference among sample groups.
For the pH of sweet and Sour sauce, the highest was 3.78±0.02 from sample group of yacon 20% mixing, showing the significant difference, and 3.62±0.04 from sample group of yacon 15% mixing, 3.53±0.02 from sample group of yacon 10% mixing, and 3.44±0.12 from reference group. This result is identical to the research result, that yacon is pure alkaline food. For the viscosity, the highest was 1238.67±172.47 cP from reference group, and the lowest was 701.87±29.95 cP from sample group of yacon 20% mixing, so viscosity was decreased according to increase the yacon mixing rate. For spreadability, the lowest was 20.47±0.26 from reference group, and 21.50±0.24, 21.93±0.42, and 23.13±0.33 each from sample group of 10%, 15% and 20% of yacon mixing. So there was significant increasing according to increasing yacon mixing. Both the test result of viscosity and spreadability have shown the coherence, and the coefficient of correlation was -0.93, negative correlation, the spreadability has been increased while the viscosity has been decreased.
From the sugar content test, the result showed significant increase as per increasing yacon mixing level, 32.5±0.46% from reference group and 33.1±0.42%, 33.3±0.55%, 33.6±0.1% each from mixing level of 10%, 15% and 20%. From antioxidant test, the result of DPPH free radical scavenging activity showed significant increase as per increasing yacon mixing level, 60.16±8.89 from reference groups, and 66.06±7.12, 69.46±3.93, 78.25±0.70 each from mixing level of 10%, 15% and 20%. Also from total phenolic compound test, it showed same tendency, like DPPH free radical scavenging activity, it has been increased as per increasing yacon mixing level, 7.19±0.11 from reference group, and 7.60±0.12, 12.16±0.18, 13.33±0.26 mg CE/100g each from mixing level 10%, 15%, and 20%, so by the result antioxidant has been increased.
From sensory test, the preference test of color, 7.21±0.77 was the highest from reference group, while 3.81±0.77 was the lowest from sample group of yacon 20% mixing. For flavor, 7.33±0.47 was the highest from reference group, and 6.72±0.80, 7.13±0.85, 7.08±0.79 each from mixing level 10%, 15%, and 20%. So there was no significant difference. For taste, 8.16±0.31 was the highest from sample group of 15% yacon mixing, but there was no significant difference with reference group, 7.55±0.51, and sample group of 10% yacon mixing, For Concentration, yacon 10% mixing group was significantly high with 7.71±0.65, but between reference group and sample group yacon 15% mixing there was no significant difference, with 5.63±0.76 and 6.28±0.85. Sample group of yacon 20% mixing was significantly low with 3.64±0.51. For softness, the highest was 7.57±0.77 from sample group of yacon 10% mixing, and followed by sample group of yacon 15% mixing with 6.17±1.51. Reference group and sample groups of yacon 20% mixing were significantly low with 3.55±0.61, 3.38±0.65. For overall acceptance, sample group of yacon 10% mixing showed significantly high with 6.93±1.29, but between reference group and sample group yacon 15% mixing there was no significant difference, with 5.49±0.76 and 6.34±1.11. Sample group of yacon 20% mixing was significantly low with 3.39±0.93. This result is similar to the test results of concentration and softness, so that it is understood that concentration and softness give the highest influence to overall acceptanc