Lifen Zhang

Henan University of Technology, Henan’an, Guangdong, China

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Publications (8)13.66 Total impact

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    ABSTRACT: Effects of ultrasound and/or heating on the yield of pectin, swelling behavior of material, and kinetics of pectin extraction from grapefruit peel were investigated. Several extraction parameters significantly affected the yield of pectin and swelling index (SI) of vegetal tissue. The optimal extraction conditions for ultrasound-assisted heating extraction (UAHE) selected through single-factor experiments were as follows: ultrasound power density 0.40 W/mL, duty cycle 50%, temperature 60 °C, solid–liquid ratio 1/50 g/mL. Image studies showed that UAHE disrupted the vegetal tissue and significantly improved its swelling behavior. There existed significantly high correlations between tissue SI and pectin yield, indicating that the improvement of pectin extractability via disrupting vegetal tissue was the main mechanism for ultrasonic enhancement of extraction. A theoretical model, which could simultaneously describe the extractability, dissolution and degradation rates of pectin, and predict the maximal yield and the optimal time, was used to study the extraction kinetics when ultrasound and/or heating were applied. Yields of pectin extracted using UAHE (0.40 W/mL and 60 °C), ultrasound-assisted extraction (UAE, 0.40 W/mL and 30 °C), heating extraction (HE, 60 °C), room temperature extraction (RE, 30 °C) and conventional heating extraction (CHE, 80 °C) within 60 min were monitored and analyzed by the model respectively. The kinetics study showed that both heating and ultrasound could significantly facilitate the extractability, dissolution and degradation of pectin, and there existed a synergistic effect between them. Compared with CHE, UAHE significantly improved the extractability and extraction rate of pectin, leading to higher yield (26.74%) with shorter extraction time (51.79 min) and reduced temperature (60 °C). These results suggested that UAHE could be an efficient technique for the extraction of pectin from plant materials.
    Journal of Food Engineering 04/2014; 126:72–81. · 2.28 Impact Factor
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    ABSTRACT: Nanostructure of water-soluble pectin (WSP) and chelate-soluble pectin (CSP) of two Chinese cherry (Prunus pseudocerasus L.) cultivars (soft cultivar 'Caode' and crisp cultivar 'Bende') with two different ripening stages were characterised using atomic force microscopy. Both cultivars shared some common values of chain widths for WSP or CSP, and both pectins shared several values of chain widths including 37, 55 and 61 nm. The results indicate that different cultivars shared similar components of pectin, and cultivar textural difference might be related to the interaction between pectin and other cherry components or the dissociation of pectin. During ripening, the wide WSP and CSP gradually dissociate in width. The results demonstrated that the changes of WSP and CSP of Chinese cherry in widths were a dissociation process. (†)The manuscript is a contribution for the special issue on the 70th birthday of Prof. Dr. Atta-ur-Rahman.
    Natural product research 05/2013; 27(4-5):379-385. · 1.01 Impact Factor
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    ABSTRACT: BACKGROUND: Modified pectin has been found to have various biological activities. The preparation of modified pectin is accomplished by either chemical or enzymatic depolymerization processes. Both of the methods have many disadvantages. Ultrasound treatment is simple, and requires shorter times and lower temperatures than other conventional techniques used for processing plant materials. The application of ultrasound to modified polysaccharide has received more attention. RESULTS: The average molecular weight of citrus pectin decreased under different ultrasonic conditions. The average molecular weight decreased from 464 kDa to 296 kDa after 30 min of sonication. The degree of methylation of citrus pectin changed slightly, and its monosaccharide component remained unchanged when high-intensity ultrasound was applied. Reduced (Gal + Ara):Rha ratio after ultrasonication suggested degradation in the neutral sugar side chains of citrus pectin. The AFM results approved the degradation of citrus pectin chains by ultrasound at nanolevel. CONCLUSION: Ultrasound is therefore an effective way to pretreat or modify pectin. The degradation of citrus pectin was due to the cavitational effects of ultrasound. It may be useful in establishing environmentally-friendly extraction and modification technologies for pectin.
    Journal of the Science of Food and Agriculture 04/2013; · 1.88 Impact Factor
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    ABSTRACT: The effects of ultrasound on the molecular weight of apple pectin were investigated. The structure and rheological properties of the degradation products were also tentatively identified by High Performance Liquid Chromatography-Photodiode Array Detector (HPLC-PAD), Infrared spectroscopy (IR), Nuclear Magnetic Resonance spectroscopy (NMR) and Rheometer. The results indicated that the weight-average molecular weight of apple pectin decreased obviously after ultrasound treatment. The molecular weight of degradation products had a uniform and narrow distribution. Ultrasound intensity and temperature play an important role in the degradation reaction. Degradation kinetics model of apple pectin fitted to 1/M(t)-1/M(0)=kt from 5 to 45°C. The degree of methylation of apple pectin reduced according to IR analysis when ultrasound was applied. Ultrasound treatment could not alter the primary structure of apple pectin according to the results determined by HPLC, IR and NMR. Meanwhile, the viscosity of apple pectin was 10(3) times as large as that of ultrasound-treated apple pectin. The ultrasound-treated apple pectin showed predominantly viscous responses (G'<G″) over the same frequency range. The results suggested that ultrasound provided a viable alternative method for the modification of pectin.
    Ultrasonics Sonochemistry 08/2012; 20(1):222-31. · 3.52 Impact Factor
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    ABSTRACT: To investigate the fundamental of firmness changes of crisp peaches, firmness and pectin contents of two peach (Prunus persica L. Batsch) cultivars (‘Cangfangzaosheng’ and ‘Songsenzaosheng’) stored at 2°C, 8°C and 15°C were investigated. Sodium carbonate-soluble pectin (SSP) extracted showed the highest correlation (positive) with firmness among the three kinds of pectins (water-soluble pectin, chelate-soluble pectin and SSP). The qualitative and quantitative information about SSP nanostructures were determined by atomic force microscopy (AFM). The widths of the peach SSPs were very consistent. The SSP chain widths of both peach cultivars were similar and were composed of several basic units. Schematic models of the changes of the chain widths were proposed. The results indicate that the firmness of peach was closely related with the contents and nanostructural characteristics of SSP, which might be hydrolyzed by enzymes in fruit flesh.
    Lwt - Food Science and Technology. 01/2010; 43(1):26-32.
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    ABSTRACT: Atomic force microscopy (AFM) was used to describe and measure the nanostructure of hemicellulose (HC) samples extracted from two cultivars of Chinese cherry, ‘Caode’ (soft) and ‘Bende’ (crisp) at different stages of ripeness. The widths of the HC molecules and aggregates are consistent with little difference between the two cultivars: 23, 29, 34 and 41 nm for ripe soft fruit and 23, 34, 39 and 41 nm for ripe crisp fruit. The results showed that crisp fruit contained a higher percentage of thicker HC chains than soft fruit, suggesting that the thickness of the HC chains may be related to the textural differences observed in the cultivars of the Chinese cherries.
    LWT - Food Science and Technology. 01/2009; 42(1):125-130.
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    ABSTRACT: Firmness and physicochemical properties of 2 Chinese cherry (Prunus pseudocerasus L.) cultivars (soft cultivar "Caode" and crisp cultivar "Bende") at unripe and ripe stages were investigated, and the qualitative and quantitative information about sodium carbonate-soluble pectin (SSP) nanostructures was determined by atomic force microscopy (AFM). The lengths and widths of the cherry SSPs are very regular: almost all of the widths and lengths of SSP single molecules are composed of several basic units. The widths of the SSP chains are 37, 47, 55, and 61 nm, and the lengths are 123, 202, and 380 nm in both cultivars. The results show that the firmer cherry groups (crisp fruit) contain more percentages of wide and short SSP chains than soft fruit, and the unripe groups contain more percentages of wide and long SSP chains than corresponding ripe groups. They indicate that those nanostructural characteristics of SSP are closely related with firmness of the Chinese cherries in each cultivar.
    Journal of Food Science 09/2008; 73(6):N17-22. · 1.78 Impact Factor
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    ABSTRACT: The extraction of an essential oil from discarded tobacco leaves using a combination of solvent extraction and steam distillation (SE–SD) was investigated. The effect of different parameters, such as temperature, extraction time and liquid–solid ratio, on the extraction yield was investigated using the Response Surface Method (RSM) with the Box–Behnken Design (BBD) method. The temperature and liquid–solid ratio were found to have a significant effect on the yield of extract (oleoresin). A yield of 3.38 ± 0.03% of the oleoresin (final essential oil yield was 0.89%) could be extracted under the following optimized conditions: a temperature of 41 °C, a liquid–solid ratio of 6.27 mL/g and a time of 5 h. Composition and characteristics of the discarded tobacco essential oils and oleoresins obtained by SE–SD, hydrodistillation and solvent extraction were analyzed by gas chromatography/mass spectrometric detection, to allow the extraction methods to be compared. The results showed that the same compounds were largely present in the different tobacco essential oils, but their relative concentrations differed. General characteristics of the extracts obtained from the three extraction methods showed that the SE–SD essential oil was of better quality and therefore of higher value. Thus, SE–SD is the optimum process for the extraction of high quality essential oil from discarded tobacco.
    Industrial Crops and Products 39:162–169. · 3.21 Impact Factor