Chongqing Sweet Potato Engineering and Technology Center

Chongqing, China

Chongqing Sweet Potato Engineering and Technology Center

Chongqing, China

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Lv X.,Southwest University | Ye F.,Southwest University | Li J.,Southwest University | Ming J.,Southwest University | And 2 more authors.
Carbohydrate Polymers | Year: 2016

Quercetin is grafted to carboxymethyl sweetpotato starch (CMSS) by esterification. Upon esterification, the water solubility of CMSS decreases and the CMSS-quercetin conjugates (CMSS-Q) are yellowish. FT-IR and 1H NMR indicated the covalent attachment of quercetin to CMSS. Thermogravimetry revealed the superior thermal stability of CMSS-Q over CMSS and native sweetpotato starch (NSS). The in vitro digestibility assays showed that CMSS is highly resistant to digestion while the quercetin graft with degree of substitution (DS) above 0.074 slightly increased its digestibility. The quercetin graft imparted CMSS with strong antioxidant activity and enhanced its thermal stability, which increased with quercetin DS. In vitro cyotoxicity assessment revealed that CMSS-Q is as safe as CMSS and NSS. This study showed that CMSS-Q is a novel antioxidant-resistant starch in RS4 form. © 2016 Elsevier Ltd


Li J.,Southwest University | Ye F.,Southwest University | Liu J.,Southwest University | Zhao G.,Southwest University | Zhao G.,Chongqing Sweet Potato Engineering and Technology Center
Food Hydrocolloids | Year: 2015

The high humidity sensitivity of glycerol plasticized starch films badly limited their applications for various foods. Stretchable sweet potato starch films with improved moisture-proof property were successfully obtained by using equivalently mixed octenylsuccinated/native starches (OSS/NS). FT-IR analysis evidenced the successful synthesis of OSS and its presence in OSS/NS blend films. The effects of the degree of substitution (DS) of OSS on the properties of the resulting blend films were evaluated. The incorporation and DS of OSS were of much importance in determining the properties of the blend films. In contrast with the control film, OSS/NS blend films presented significantly improved moisture-proof property as indicated by the lower values in water solubility and water vapor permeability, and the higher values in contact angle and oil permeability. The amplitudes of these improvements varied with the increasing DS of OSS. Meanwhile, the stretchability, elongation at break and transparency of OSS/NS blend films were higher than those of the control film and increased with the increasing DS of OSS. Oppositely, the results of XRD showed that OSS/NS blend films owned lower crystallinity compared with the control film. These variations were virtually ascribed to the hydrophobicity of OSS and the plasticization of octenyl groups in film formation. Frankly speaking, incorporating OSS into sweet potato starch film is a double-edged sword, providing positive effects by enhancing moisture-proof property, stretchability, elongation at break and transparency while simultaneously triggering deterioration in tensile strength and/or structural homogeneity. © 2014 Elsevier Ltd.


Li J.,Southwest University | Song H.,Southwest University | Dong N.,Southwest University | Zhao G.,Southwest University | Zhao G.,Chongqing Sweet Potato Engineering and Technology Center
Food Science and Biotechnology | Year: 2014

Storage (4°C and 25°C, 28 days) and thermal (70°C-90°C, 6 h) stabilities of purple sweet potato anthocyanins (PSPAs) with varying concentrations of ascorbic acid (AA) were investigated in a model soft drink medium. For storage stability, the model drink was sterilized at 85°C for 15 min prior to storage. Zero-order kinetics and first-order kinetics were fitted for storage degradation at 4°C and 25°C, respectively. However, all data for thermal degradation fitted first-order kinetics. The temperature dependence on degradation was modeled after the Arrhenius equation. Storage degradation of PSPAs was increased by the presence of AA (40-360 mg/L). Retarded thermal degradation was be achieved by adding 120 mg/L of AA, while accelerated thermal degradation resulted from 360 mg/L of AA. Heat treatment did not markedly change the DPPH radical-scavenging activity of PSPAs. © 2014 The Korean Society of Food Science and Technology and Springer Science+Business Media Dordrecht.


Shen X.L.,Southwest University | Shen X.L.,China Agricultural University | Wu J.M.,Southwest University | Chen Y.,China Rural Technology Development Center | And 3 more authors.
Food Hydrocolloids | Year: 2010

Antimicrobial biodegradable films have been prepared with sweet potato starch by incorporating potassium sorbate or chitosan. Films incorporated with potassium sorbate ≥ 15% or chitosan ≥ 5% were found to have an anti-Escherichia coli effect. Staphylococcus aureus could be effectively suppressed by incorporation of chitosan at ≥10%. Whereas potassium sorbate lowers the tensile strength and elongation at break, and raises the oxygen permeability, water vapor permeability and water solubility, chitosan has the opposite effect. Fourier Transform Infrared (FT-IR) spectra analysis revealed that starch crystallinity was retarded by potassium sorbate incorporation and that hydrogen bonds were formed between chitosan and starch. This explained the modification of the mechanical and physical properties of the films by the incorporation of these two antimicrobial agents. © 2009 Elsevier Ltd. All rights reserved.


Liu J.,Southwest University | Ming J.,Southwest University | Li W.,University of Sichuan | Zhao G.,Southwest University | And 2 more authors.
Food Chemistry | Year: 2012

Carboxymethyl potato starch was synthesised with the aid of microwave. Optimal degree of substitution (DS) of 0.32 was obtained at 45°C in 25 min using aqueous ethanol media with water/solvent of 0.15 at 200 W. The molar ratio of sodium hydroxide and monochloroacetic acid to anhydroglucose unit for optimal DS were 2.5 and 1.0, respectively. FT-IR spectrometry revealed the carboxymethyl starch to show new bands at ν = 1614 cm -1 and ν = 1429 cm -1. Wide angle X-ray diffractometry and DSC revealed a remarkable reduction in starch crystallinity after carboxymethylation, which was consistent with destroyed surface observed in SEM. The digestibility of carboxymethyl starch (CMS) was lower than that of native starch. With similar DS, there was no difference in digestibility of carboxymethyl starch prepared with and without microwave. As DS increased from 0.05 to 0.32, the amount of resistant starch in microwave-assisted carboxymethyl starch was elevated from 14.6% to 20.0%, which was much higher than that of native starch (10.8%). © 2011 Elsevier Ltd. All rights reserved.


Liu J.,Southwest University | Chen J.,Southwest University | Dong N.,Southwest University | Ming J.,Southwest University | And 4 more authors.
Food Chemistry | Year: 2012

The degree of substitution (DS) markedly affects the properties of carboxymethyl starch (CMS). The conventional methods for the DS determination are time-consuming and not environment friendly. Fourier transform mid-infrared (FT-MIR) spectroscopy coupled with partial least squares (PLS) regression is applied to determine the DS of CMS in the present study. Calibration models with direct titration as the reference method were optimised by cross validation. A PLS regression model with a coefficient of determination (R 2) of 0.9593 and root-mean-square error of cross validation (RMSECV) of 0.0141 was obtained in the spectral range from 500 to 4000 cm -1. The prediction set gave a coefficient of determination (R 2) and root-mean-square error of prediction (RMSEP) of 0.9368 and 0.0228, respectively. The results obtained in this study indicate that FT-MIR spectroscopy can be used as an easy, rapid, and novel tool to quantitatively predict the DS of CMS. © 2011 Elsevier Ltd. All rights reserved.


Liu J.,Southwest University | Wena Y.,Southwest University | Dong N.,Southwest University | Lai C.,Southwest University | And 3 more authors.
Food Chemistry | Year: 2013

Fourier transform mid infrared (FT-MIR) spectroscopy combined with chemometrics techniques were developed for classification and quantification of cheaper starches (potato and sweet potato starch) in lotus root powder (LRP). By performing principal component analysis (PCA), it was possible to distinguish between adulterated and non-adulterated LRP. The coefficient of determination (R2) and standard deviation ratio (SDR) of calibration set were found to be 0.9587-0.9898 and 3.63-10.2, depending on the pretreatment of spectra. The external validation set gave a coefficient of determination (R2) and standard deviation ratio (SDR) of 0.9810 and 5.47, respectively. Moreover, the limit of detection (1%), the limit of quantification (3%), reasonable recovery (92.3-101.5%), satisfactory intra-assay (2.9-5.5%) and interassay (11.0-13.5%) precision illustrated the good performance of the present method. The results obtained in this study indicate that FT-MIR spectroscopy can be used as an easy, rapid and novel tool to detect the LRP adulterated with cheaper starches. © 2013 Elsevier Ltd. All rights reserved.


Guan Y.,Southwest University | Ye F.,Southwest University | Liu J.,Southwest University | Zhao G.,Southwest University | Zhao G.,Chongqing Sweet Potato Engineering and Technology Center
Journal of Agricultural and Food Chemistry | Year: 2013

The interaction between ε-polylysine (ε-PL) and anionic polysaccharides has gained considerable attention recently because of its scientific impact on the stability and appearance of liquid food systems. The purpose of this study was to characterize the interactions between ε-PL and carboxymethyl sweet potato starch (CSS) using isothermal titration calorimetry (ITC), electrical charge, and turbidity measurements. The results showed that the interaction between ε-PL and CSS was electrostatic and mainly dependent on the molar ratio of amino groups in ε-PL to carboxyl groups in CSS. Additionally, the interaction between ε-PL and CSS was also associated with pH, degree of substitution (DS) of CSS, and ionic strength of the system. For the interaction of ε-PL with high DS (>0.235) CSS, three states of the ε-PL/CSS mixture were observed as transparent, turbid, and precipitated with a successive increase in amino/carboxyl molar ratio. Distinguishingly, a transparent mixture could be obtained for CSS with low DS (0.114) at a sufficiently high amino/carboxyl molar ratio. The present study provided basic guidance in designing liquid food systems containing both ε-PL and CSS. © 2013 American Chemical Society.


Peng Z.,Southwest University | Li J.,Southwest University | Guan Y.,Southwest University | Zhao G.,Southwest University | And 2 more authors.
LWT - Food Science and Technology | Year: 2013

This work focuses on the impact of carriers on the physicochemical properties, antioxidant capacities and biological components of spray-dried purple sweet potato flours. The optimal carrier addition of maltodextrin (MD), β-cyclodextrin (β-CD) and their combination (MD/β-CD, 5/1) were 30, 10 and 24 g/100 g in terms of flour yield. Compared to the flour without carrier, flours with carriers had higher values in L*, fluidity, water solubility index, glass transition temperature, lower values in chroma, water absorption index and water holding capacity. The influence intensity of carriers on the physicochemical properties of flours followed the sequence of MD > MD/β-CD> β-CD. The flours with carriers were more dispersive and had smoother surface than flour without carrier. The addition of carrier had little effects on flours' sorption isotherm and the Halsey model presents the best goodness-of-fit to all flours. The flour with MD had higher retention rate of anthocyanins, flavonoids and total phenolics than flours without and with other carriers. The flour with MD has higher antioxidant activity (DPPH test) than flours with MD/β-CD or β-CD. © 2012 Elsevier Ltd.

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