• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.2
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• pp.79-82
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• 2000

Tuberous root of yacon (Polymnia sonchifolia Poeppig ＆ Endlicher) has not starch, and its brix degree changes during the curing. Therefore its chemical composition changes were investigated according to different curing conditions. Tuberous root contained 87.1% moisture at harvesting, that was decreased to 84.1-86.0% at 30 days after curing in different curing conditions. Brix degree was increased from 5.7 to 14.2-15.8% at 30 days after curing in comparison to at harvesting. Free sugars were detected from tuberous root in yacon by HPLC; that were fructose, glucose and sucrose. Fructose contents were increased from 0.09 to 1.04-1.79% during 30 days in five curing conditions. Glucose contents were shown to increase from 0.03 to 1.04-1.37 %. Sucrose contents were shown to increase from 0.04 to 0.13-0.43%. Tuberous root contained fructose, glucose and sucrose in order of amount that were highest in single-polyethylene film covered green house. Sucrose was little as comparison with fructose and glucose. Fructose and glucose were increased to 16.7 and 40.7 times, respectively, but sucrose was increased little about 6.8 times.

• Journal of Life Science
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• v.20 no.1
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• pp.40-48
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• 2010

This study was carried out to investigate the physicochemical and functional properties of Yacon (Polymnia Sonchifolia) powder. The proximate composition of Yacon powder as a dry matter basis was 3.53% moisture content, 1.13% crude protein, 0.40% crude fat, 0.79% crude ash, 1.63% dietary fiber and 92.52% carbohydrate. The major free sugars were identified as fructose and glucose. Analysing total amino acids, 18 kinds of components were isolated from Yacon powder. The essential amino acid contained in Yacon powder accounted for 28.40% of total amino acid, while the non-essential amino acid accounted for 73.61%. Analysing total fatty acids, only 2 kinds - palmitic acid and lauric acid - were detected. Oxalic acid was the major organic acid. The contents of vitamin A, vitamin C and vitamin E were 0.057 mg%, 0.670 mg% and 0.001 mg%, respectively. The mineral contents of Yacon powder were in the order of Zn

• Korean Journal of Medicinal Crop Science
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• v.9 no.3
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• pp.232-237
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• 2001

This study was carried out to know the effect of light intensity, temperature and $CO_2$ concentration on photosynthesis and transpiration in yacon(Polymnia sonchifolia Poepp.& Endl.). Light compensation point was ${58\;{\mu}mol\;m^{-2}\;s^{-1}}$and light saturation point was ${1708\;{\mu}mol\;m^{-2}\;s^{-1}}$. Transpiration rate was increased to about 4 mmol${m^{-2}\;s^{-1}}$ with increasing of light intensity to ${2193\;{\mu}mol\;m^{-2}\;s^{-1}}$. The optimum temperature for photosynthesis was ${24^{\circ}C}$ in air. Photosynthesis was gradually reduced as transpiration rate increased from 4 to 8 mmol ${m^{-2}\;s^{-1}}$ in different air temperature. $CO_2$ compensation point was 63 vpm and $CO_2$ saturation point was 1155 vpm and light saturation point was enhanced with increasing of $CO_2$ concentration from 350 vpm to 1300 vpm.

• Proceedings of the Korean Society of Crop Science Conference
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• 1997.10a
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• pp.82-83
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• 1997

• Proceedings of the Korean Society of Crop Science Conference
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• 1997.10a
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• pp.84-85
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• 1997

• Korean Journal of Plant Resources
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• v.9 no.3
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• pp.274-278
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• 1996

This study was conducted to examine the dry matter production and leaf photosynthesis under different fertilizer application in Yacon(Polymnia sonchifolia)plants. Under field conditions, dry matter production of stable mature application plot(S-1) was much larger than non-treated control plot(CTL), but bulb dry weight of 10kg nitrogen application plot per 10a (N-10) was not differentiated from CTL. The maximum photosynthetic rates increased in Yacon plants grown at S-1 while in the rates of CTL reduced under glasshouse in the same treated pot condition. The optimum temperature for the highly photosynthetic rates is about $34{\pm}3^{\circ}C$, and the rates did decrease by stomatal resistance below 28℃. The estimated light saturation point was $1200{\mu}mol{\cdot}m^{-2}s^1$. The results of this study indicate that soil conditions were highly related to dry matter production and leaf photosynthesis rate in Yacon plants.

• Korean Journal of Medicinal Crop Science
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• v.15 no.1
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• pp.17-20
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• 2007

This study was conducted to investigate the effect of various composts and NPK fertilization rates on the growth of yacon (Polymnia sonchifolia POEPP). Fertilization of used soil was low. Mean temperature of July was higher than that of normal year, but those of another months were same or the lower. The yield of the no-compost plot was higher by 74% than the no-fertilization plot. Increased NPK fertilization rates of bark compost and organic fertilizer plots increased the growth and yield of yacon. The yield of bark compost 1.5 times plot was highest by 6,905 ㎏/10a. The chemical contents of leaves in the various compost and NPK fertilization rates were not normal tendency, and also that of no-compost plot was not difference to the NPK fertilization rates plot.

• Food Science and Preservation
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• v.9 no.1
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• pp.61-66
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• 2002

Chemical composition of fresh and dried leaves and stems and fresh and cured tubers of bacon (Polymnia sonchifolia) was investigated. The moisture content of fresh leaves, stems, and tubers was 83.38, 92.30 and 89.52%, and there of dried leaves and stems were 18.08 and 27.97% and that of cured tubers was 27.97%. The content of lipid, protein, soluble solid, ascorbic acids chlorophyll and tannin was higher in leaves of yacon than in stems of that. In fresh and cured yacon, the content of protein were 0.04% both of them, of lipid was 0.31 and 0.54%; of ash, 0.40 and 0.42%; of ascorbic acids 2.77 and 2.87 mg/100 g. The major minerals of leaves, stem, and tubers of bacon were P, K, and Mg. The major free sugars of leaves, stems and tubers of bacon were glucose and fructose and after curing all free sugars of tubers of bacon were increased. The most abundant free amino acid was isoleucine in the leaves, stem, and tubers of bacon. The content of beta-carotene was 9.01 $\mu\textrm{g}$/100g in fresh leaves and 107.87 $\mu\textrm{g}$/100 g in dried leaves, and 0.40 $\mu\textrm{g}$/100 g in fresh tubers of bacon and 055 $\mu\textrm{g}$/100 g in cured tubers.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.3
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• pp.374-381
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• 2013

The purpose of this study was to analyze the antioxidant effects and antimicrobial activity of extracts from yacon powder. The total polyphenol contents of yacon powder extracted with methanol was 38.5 mg/g, while extracted with water was 24.0 mg/g. Extractions with methanol were therefore more effective than with water. The total flavonoid contents of yacon powder extracted with methanol was 9.2 mg/g, while that with water was 7.8 mg/g. The electron donating ability of yacon powder extracts, natural antioxidant, and artificial antioxidant at 1.0 mg/mL arranged in order of decreasing concentration were ascorbic acid (98.7%) > BHT (44.7%) > methanol extract (12.1%) > water extract (7.8%). Nitrite-scavenging ability of yacon powder extracted with methanol at pH 1.2 was 13.1%, while that of powder extracted with water at pH 1.2 was 6.8%. And, the hydroxyl radical scavenging activities of yacon powder with methanol at 5 mg/mL was 40.2%. The antimicrobial activity of yacon powder extracted with methanol could be detected on Bacillus cereus ($10,000{\mu}g/disc$) and Staphylococcus aureus ($10,000{\mu}g/disc$).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.5
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• pp.300-304
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• 2000

Tuberous roots of yacon (Polymnia sonchifolia Poeppig ＆ Endlicher) were stored in different temperature and relative humidity conditions after curing for 30 days. Non-decadent percentage, moisture contents, brix degree and sugars were investigated. Whether temperature and relative humidity were high or not, most of the tuberous root decayed during storage, and the decayed percentage was increased as long as the storage period. In final, only 13% of tuberous roots remain intact at 4$^{\circ}C$, 85% relative humidity condition to be appeared best storage condition in this experiment and all of the tuberous root decayed in other storage conditions after 6 months. Moisture contents decreased a little in the high relative humidity. Even though tuberous roots decayed when stored at 1$0^{\circ}C$ and 2$0^{\circ}C$, most of brix degree reached about 17.0. Fructose, glucose and sucrose contents were 1.65, 1.15 and 0.35% at early storage period, and 1.6, 1.1 and 0.5% after 6 months at 4$^{\circ}C$, 85% relative humidity, respectively. In 3 temperature conditions, fructose and glucose increased for a month and then decreased successively afterwards, but sucrose increased gradually during 6 months. Also in 4 relative humidity conditions, fructose, glucose and sucrose contents were changed with similar to that of in temperature. Changes of fructose and glucose were the same except on 4$^{\circ}C$, 85% relative humidity, that was lower level than moisture of tuberous root.