• Microbiology and Biotechnology Letters
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• v.37 no.3
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• pp.266-272
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• 2009

The annual productions of yam and its aerial bulbils are estimated to 5,000 and 2,500 ton, respectively. But the majority of bulbils had been discarded without specific use. In this study, methanol extract and its organic solvent fractions were prepared from bulbils of Dioscorea batatas Decne, and their antimicrobial, antithrombin, and antioxidant activities were evaluated, respectively. The methanol extract contained 58.98% of water-soluble materials as like yam's extract. But the bulbils's extract contained 12-folds of total polyphenol and 3.4-folds of total flavonoids compared than yam's extract, respectively. For antimicrobial activity the hexane and ethyl acetate fraction showed strong antibacterial activity at $500{\mu}g/disc$ concentration against gram-negative and gram-positive bacteria. Antifungal activity was not observed in any fractions. Strong antithrombin activity was found in the hexane fractions. At 4.8 mg/mL concentration thrombin time (TT) was over 300 sec, which is 4-folds extended than the TT of yam. In a while, the ethyl acetate fraction showed strong DPPH scavenging activity ($IC_{50}$ of $38.1{\mu}g/mL$), SOD-like activity and reducing power, which are comparable to vitamin C or BHT. Our results suggest that the bulbils of yam as yam tuber have useful bio-activities, such as antibacterial, antithrombosis, and antioxidant activity.

• Journal of Life Science
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• v.20 no.9
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• pp.1365-1372
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• 2010

We investigated the inhibitory effects of solvent extracts from dried yam on $H_2O_2$-induced oxidative stress and growth of cancer cell lines (HT1080 human fibrosarcoma and HT-29 human colon cancer cells). Yam (Dioscoreacea) has been recognized as a healthy food due to its various biological activities, such as anti-obesity, anti-constipation, anti-proliferation, and anti-mutagenic activities, as well as its ability to decrease blood glucose and cholesterol levels. In order to determine the protective effect on $H_2O_2$-induced oxidative stress, DCFH-DA (dichlorodihydrofluorescin diacetate) assay was conducted. Acetone with methylene chloride (A+M) extract of dried yam appeared to reduce the levels of intracellular reactive oxygen species (ROS) with dose responses. Among the fractions, 85% aq. methanol fraction showed the highest protective effect on production of lipid peroxides. Inhibitory effects of A+M and methanol (MeOH) extracts on the growth of HT1080 and HT-29 cancer cells increased in a dose dependent manner. The treatments of n-hexane, 85% aq. methanol and n-butanol fractions (${\geqq}0.5$ mg/ml concentrations) significantly inhibited the growth of both cancer cells (p<0.05). From these results, 85% aq. methanol fraction showed inhibitory effects on cellular oxidation and growth of human cancer cells, suggesting that this fraction may contain active compounds of dried yam.

• Culinary science and hospitality research
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• v.20 no.6
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• pp.56-68
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• 2014

Yam Yackwa (YP) was made by addition of yam power (15%) into flour. Depending on extension of storage time, lightness and redness of YP were increased. Yellowness of YP was decreasing until 3 days and increased from 9 days of storage. However, the yellowness of Yackwa without Yam powder (Non-YP) was increasing until 3 days and decreased from 6 days of storage. Hardness, gumminess, and chewiness of YP were improved compared to Non-YP. It means that the addition of yam power makes Yackwa soft. Oil absorption of Non-YP was low. Acid value and peroxide value of YP were 1.57 and 19.04, respectively. Moisture contents, crude ash, crude fat, crude protein, and carbohydrate of YP were $2.55{\pm}0.08%$, $0.71{\pm}0.01%$, $6.11{\pm}0.06%$, $15.97{\pm}1.40%$, and $64.66{\pm}0.09%$, respectively.

• Korean Journal of Microbiology
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• v.50 no.1
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• pp.53-59
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• 2014

This study was conducted to investigate the characteristics between non-fermented chinese yam and rice (non-FCYR) and fermented chinese yam and rice (FCYR). 1.1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, total polyphenol, flavonoid contents and reducing power were investigated to evaluate the anti-oxidation activities of FCYR. Also, productivity of monacolin K, major medicinal ingredient of FCYR, was investigated, using Aspergillus terreus KCCM 12225. In case of non-FCYR, DPPH radical scavenging activities for three kinds of yam (Dioscorea japonica, Dioscorea batatas, Dioscorea opposita) and rice were estimated about 51.8, 66.4, 42.2 and 7.5%, while in case of FCYR, those for three kinds of yam and rice were estimated to increased about 64.7, 74.7, 52.8, and 32.3%, respectively. Total polyphenol contents of non-FCYR were estimated to 196.9, 265.7, 160.1, and 91.6 mg/kg, while total polyphenol contents of FCYR were estimated to increase about 530.7, 708.3, 427.2, and 265.9 mg/kg, respectively. Total flavonoid contents of FCYR increased to 2.8-3.3 times higher than those of non-FCYR. Reducing power of non-FCYR was about 0.97, 1.28, 0.64, and 0.17 (OD at 700 nm), while, that of FCYR increased about 1.75, 2.38, 1.24, and 0.46. Remakable increase in monacolin K productivity of FCYR was observed. Monacolin K productivity of FCYR was estimated to 467.1, 514.8, 339.2, and 272.5 mg/kg, respectively. In this study, fermented chinese yam (Dioscorea batatas) was estimated to be effective biological activity material.

• Korean Journal of Food Science and Technology
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• v.33 no.6
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• pp.795-801
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• 2001

Effects of Mucilage fraction from Yam (Dioscorea batatas DECENE), which has long been used as a wild vegetable and folk medicine, on blood glucose and lipid composition in alloxan-induced diabetic mice were investigated. Diabetes mellitus was induced in male ICR mice by the injection of alloxan into the tail vein at a dose of 75 mg/kgBW. Alloxan-induced diabetic mice were administered the yam mucilage fraction1 orally ; y500F1 group (500 mg/kgBW/day fraction1) and y750F1 group (750 mg/kgBW/day fraction1); and the normal and alloxan-control group were orally administered with saline for 10 days. The body weight gain and food intake were monitored every day. The concentrations of glucose, triglyceride, total cholesterol, and LDL-cholesterol of serum and liver levels of glucose, triglyceride, and cholesterol were determined. Also weight of liver, heart, spleen and kidney were measured. The fraction 1 of yam mucilage lowered body weight gain significantly (p<0.05) and decreased serum glucose levels in alloxan-induced diatetic mice compared to that of alloxan-control group. In alloxan induced diabetic mice serum triglyceride level was lowered and liver HDL-cholesterol level increased significantly (p<0.05). In conclusion, it was assumed that yam mucilage fraction 1 has anti-hyperglycemic and anti-obesitic effects by reducing body weight gain and decreasing serum glucose and triglyceride level.

• Food Engineering Progress
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• v.23 no.2
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• pp.125-133
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• 2019

The characteristics of extracts and precipitates after extraction at different water temperature (25, 50, 75, 95℃), ethanol ratio (25, 50, 75, 100%), and extraction method (stir, soak, autoclave) of yam powder and raw yam were investigated. The total polyphenol content was the highest in the 50% ethanol extract of yam powder. The DPPH radical scavenging activity was the highest in the 75% ethanol extraction and the crude saponin content was the highest in the 95℃ water extraction. Tyrosinase inhibitory activity was the highest in 95℃ water extraction, low concentration of ethanol extraction, and autoclave extraction. The peak viscosity, trough, and final viscosity of the precipitates increased after ethanol extraction, whereas decreased after the 95℃ water extraction and the autoclave, indicating the destruction of starch granules. This was confirmed by observing the starch granules broken using the SEM. The significance of this study was to investigate the possibility of the use of yam resources as a material, processing product development, skin beauty functional food and cosmetic material.

• Proceedings of the Korean Society of Life Science Conference
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• 2006.09a
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• pp.81.2-81.2
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• 2006

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.4
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• pp.281-285
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• 2003

For storage periods of tubers in Chinese yam, the levels of $\textrm{GA}_{44}$ and $\textrm{GA}_{20}$ was constant, meanwhile both $\textrm{GA}_{53}$ and $\textrm{GA}_{19}$ level were always higher than that of $\textrm{GA}_{44}$ and $\textrm{GA}_{20}$ㆍ $\textrm{GA}_9$ content as precursor of $\textrm{GA}_4$ was not changed during storage. $\textrm{GA}_{24}$ content was low to below 0.2 ng for 90 days after storage, $\textrm{GA}_{36}$ content as precursor of $\textrm{GA}_4$ like $\textrm{GA}_9$ was about 6-8 fold higher than that of $\textrm{GA}_9$ during storage. GA contents of the two gibberellin biosynthetic pathways were gradually increased when storage periods were progressed. Bioactive GA$_1$ content as the GA members of an early C-13 hydroxylation was always constant, and its content was very low as below 0.1ng per dry weight, meanwhile, bioactive $\textrm{GA}_4$ content as the GA members of non C-13 hydroxylation was drastically increased, also, its content was highest at 90 days after storage, and then decreased at 120 days after storage. Consequently, we suggest that $\textrm{GA}_4$ may be involved in controlling tuber sprouting in Chinese yam.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.2
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• pp.68-72
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• 2003

The metabolism of [$^{14}\textrm{C}$] $\textrm{GA}_{12}$ in the Chinese yam (Dioscorea opposita Thunb. var. Tsukune) was examined to determine the identification of endogenous gibberellins. [$^{14}\textrm{C}$] $\textrm{GA}_{12}$ was metabolized to $\textrm{GA}_{53}$, $\textrm{GA}_{44}$, $\textrm{GA}_{19}$, $\textrm{GA}_{20}$, $\textrm{GA}_1$, $\textrm{GA}_8$, $\textrm{GA}_{15}$, $\textrm{GA}_{24}$, $\textrm{GA}_9$, $\textrm{GA}_{36}$ and $\textrm{GA}_4$. Radioactivity of GAs in non C-13 hydroxylation route was five-fold higher than that of early C-13 hydroxylation in analyzed GA-metabolites. Radioactivity of $\textrm{GA}_4$ was always four times higher than that of $\textrm{GA}_1$ at every feeding time. $\textrm{GA}_1$ radioactivity has always a lower level to below 200 DPM. The major pathway of endogenous GA metabolism in seedlings of the Chinese yam might be the non C-13 hydroxylation pathway.

• Fibers and Polymers
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• v.7 no.3
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• pp.317-322
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• 2006

Reduction of yam hairiness by nozzles in ring spinning and winding is a new approach. Simulation of the airflow pattern inside the nozzles provides useful information about actual mechanism of hairiness reduction. The swirling air current inside the nozzles is capable of wrapping the protruding hairs around the yam body, thereby reducing yam hairiness. Since production rate of winding is very high and the process itself increases yarn hairiness any method to reduce the hairiness of yarns at this stage is a novel approach. A CFD (computational fluid dynamics) model has been developed to simulate the airflow pattern inside the nozzles using Fluent 6.1 software. In this study, both S- and Z-type nozzles having an axial angle of 500 and diameter of 2.2 mm were used for simulation studies. To create a swirling effect, four air holes of 0.4 mm diameter are made tangential to the inner walls of the nozzles. S- and Z-twisted yams of 30 tex were spun with and without nozzles and were tested for hairiness, tensile and evenness properties. The total number of hairs equal to or exceeding 3 mm (i.e. the S3 values) for yam spun with nozzle is nearly 49-51 % less than that of ring yams in case of nozzle-ring spinning, and 15 % less in case of nozzle-winding, while both the yarn types show little difference in evenness and tensile properties. Upward airflow gives best results in terms of hairiness reduction for nozzle-ring and nozzle wound yams compared to ring yarns. Yarn passing through the centre of the nozzle shows maximum reduction in S3 values.