• Biotechnology and Bioprocess Engineering:BBE
• /
• v.11 no.4
• /
• pp.372-376
• /
• 2006

Ferulic acid is a phenolic compound that serves as a major biosynthetic precursor of vanillin in higher plants. We investigated the ability of the 3 commercial enzymes - Ultraflo L, Viscozyme L, and ${\alpha}-Amylase$ - to induce the release ferulic acid from the Ipomoea batatas L. (sweet potato) stem. The rate of release for ferulic acid was optimal when Ultraflo L (1.0%) was used compared with the other enzymes, whereas Viscozyme L was most effective for the release of vanillic acid and vanillin. Thus, these enzymes may be useful for the large-scale production of ferulic acid and other phenolic compounds from sweet potato stem.

• Korean Journal of Food Science and Technology
• /
• v.2 no.2
• /
• pp.1-7
• /
• 1970

1) A process was described for the preparation of drum-dried weaning food containing about 20% protein and based on a blend of sweet potato, full-fat soy flour, minerals, vitamins and methionine. 2) The protein efficiency ratio of this product was 2.63 as compared to 3.30 for the blend containing corn starch in place of sweet potato. This is attributed to the partial destruction of available lysine in the presence of sweet potato during the drum-drying process. 3) Overall nutritive value of the weaning food was comparable to milk food and control food based on corn starch and soy flour in terms of feed efficiency, body composition and protein retention.

• Plant Biotechnology Reports
• /
• v.2 no.4
• /
• pp.253-258
• /
• 2008

The cDNA of the touch-induced genes (TCH) of the sweet potato [Ipomoea batatas (L.) Lam.] has been cloned and analyzed. IbTCH1, which exists as at least two-copy genes in the genome of the sweet potato, encodes for 148-amino acid polypeptides, and harbors four conversed $Ca^{2+}-binding$ motif EF-hands. IbTCH1 was shown to be expressed in the flower, leaf, thick pigmented root, and particularly in the white fibrous root, but expressed only weakly in the petiole. IbTCH1 is upregulated upon exposure to environmental stresses, dehydration, and jasmonic acid. Furthermore, IbTCH1 is developmentally regulated in the leaf and root. These results strongly indicate that the gene performs functions in both plant development and in defense/stress-signaling pathways.

• Korean Journal of Food Science and Technology
• /
• v.29 no.3
• /
• pp.497-501
• /
• 1997

Kinetic parameters on heat-induced color changes of anthocyanin pigment from purple sweet potato were determined in the temperature range of $121{\sim}141^{\circ}C$. Color change determined by a browning index $(A_{532}\;nm/A_{420}\;nm)$ followed second order reaction kinetics. Activation energy values of purple sweet potato pigment solutions of pH 2.0, 3.0, 4.0 and 5.0 were 69.57, 76.68, 81.07 and 92.98 kJ/mol, respectively, indicating that temperature dependency of the reaction increased with pH. Apparent kinetic compensation effect between preex-ponential factor and activation energy value was observed.

• Preventive Nutrition and Food Science
• /
• v.13 no.3
• /
• pp.245-248
• /
• 2008

The effects of native sweet potato starch (NSPS) and sweet potato starch modified by acetylation (MSPS) on dynamic rheological properties of surimi sols were investigated by small-deformation oscillatory measurements. Dynamic frequency sweeps of surimi sols at $10^{\circ}C$ showed that the addition of NSPS and MSPS resulted in a reduction of storage modulus (G') and loss modulus (G"). The tan $\delta$ values (ratio of G"/ G') of all samples were in the range of $0.15{\sim}0.54$ over a wide range of frequency, indicating that all surimi sols are more elastic than viscous. The characteristic G' thermograms of surimi sols during heating from 10 to $90^{\circ}C$ were influenced by the addition of starch. The tan $\delta$ values of all samples were maintained nearly constant above $45^{\circ}C$, showing that the G' is proportional to the G" irrespective of starch effects.

• Food Engineering Progress
• /
• v.15 no.2
• /
• pp.169-174
• /
• 2011

This study was performed to analyze the effects of ultra fine pulverization (UFP) on the physicochemical properties of sweet potato starch (SPS). The average diameter and specific surface area of the SPS was decreased from 22.94 to 10.25 $\mu$m and from 0.879 to 1.909 $m^2$ /g throughout UFP, respectively, and the damaged starch content was increased from 13.7 to 99.2%. The pulverized sweet potato starch (PSPS) had higher swelling power, solubility, and transmittance values than the SPS. X-ray diffractograms revealed that the SPS had a C-type pattern, which disappeared in PSPS. The rapid visco analysis (RVA) characteristics, peak viscosity, break down, and set back of SPS ceased to exist in PSPS. According to differential scanning calorimetry (DSC) curves, the peak temperature ($T_p$) and gelatinization enthalpy ($\Delta$E) of SPS were $71.95^{\circ}C$ and 10.40 J/g, respectively, while these remained undetected in PSPS. The enzymatic digestibilities of SPS and PSPS were 61.7 and 84.7%, respectively.

• Food Engineering Progress
• /
• v.15 no.1
• /
• pp.34-40
• /
• 2011

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.

• Journal of the Korean Society of Food Culture
• /
• v.24 no.6
• /
• pp.756-761
• /
• 2009

The objective of this study was to assess the quality characteristics of almond Dasik prepared with the addition of purple sweet potato powder (PSPP). Five different levels (0, 5, 10, 15, and 20%) of PSPP were added and the physicochemical properties of the Dasik were examined. Crude protein and crude fat contents decreased as the level of PSPP increased (p<0.05). The Hunter L-value decreased while the a-value increased as the PSPP level increased. Texture measurements showed that the addition of PSPP increased hardness, cohesiveness, and brittleness. Total polyphenol content and antioxidant activity were assessed in terms of estimating the functionality of the Dasik. The results showed that incorporating PSPP into the Dasik provided higher polyphenol content and antioxidant activity compared to the control Dasik (p<0.05). The results of a consumer acceptance test revealed that the Dasik sample made with 15% PSPP was most preferred and the 20% sample was the least preferred. Therefore, it is suggested that purple sweet potato powder can be incorporated into Dasik up to 15% without reducing its quality.

• Korean Journal of Agricultural Science
• /
• v.11 no.1
• /
• pp.114-119
• /
• 1984

In order to improve the quality of silages made of rice straw, clover and sweet potato stalk, crushed fresh sweet potatoes(CFSP) were added at various levels to each silage. When the fermentation was completed, the chemical composition, pH and main organic acid contents of each silage were analized. The results obtained were summarized. 1. The moisture content of sweet potato stalk silage was highest among all silages tested. The clover silage showed the highest value in crude protein content. On the other hand, the rice straw silages were high in NFE and crude fiber contents. When the level of CFSP increased, the NFE contents tended to increase and crude fiber decrease. 2. The content of total organic was highest in clover silage. However, the percentage of lactic acid in total acid content was highest in sweet potato silage. The percentage of lactic ac id in total acid content was increased in paralled with the levels of CFSP. 3. The sweet potato stalk silages showed the lowest pH value (4.10-4.20). The highest pH values were 4.75-5.22 in rice straw silage. The addition of CFSP tended to lower the pH. 4. It appears the quality of clover and rice straw silages can be imp roved by adding CFSP at 5 and 10% levels, respectively, on fresh weight basis. The addition of CFSP to the sweet potato stalk silage, however, was not effective in this experiment.

• Food Science and Preservation
• /
• v.13 no.4
• /
• pp.438-444
• /
• 2006

This study was carried out to obtain fundamental data such as peeling efficiency and quality of potatoes and sweet potatoes peeled by hand, machine and alkali(NaOH). The weight loss by peeling was influenced by peeling methods. Weight losses by rotational brushing-type peeler showed the lowest value, 7.9% in potato, and 7.3% in sweet potato. Any significant differences in moisture content were not found in potatoes and sweet potatoes by peeling methods. The pH of potatoes and sweet potatoes just after peeling were 5.8-6.8 and 6.23-6.63, and decreased somewhat until 3 hrs after peeling. Hardness of potatoes and sweet potatoes peeled by hand with fruit knife were better than that of others. Depending upon the peeling method used the color and color differences undergo some changes in their color and browning. Color difference value of peeled potatoes by hand with a technical tools, and by mechanical peeler such as rotational cutting-type peeler and rotational brushing-type peeler showed just slightly. In particular, changes of rotor differences value of potatoes and sweet potatoes peeled by dipping with 10% NaOH solution at $100^{\circ}C$ was the highest in the samples peeled by NaOH.