Lingyi Liu | University of Nebraska Lincoln (original) (raw)

Papers by Lingyi Liu

European Journal of Lipid Science and Technology, 2018

Natural phenolic compounds have been drawn a wide attention to replace the synthesis antioxidants... more Natural phenolic compounds have been drawn a wide attention to replace the synthesis antioxidants due to the food safety issues, while, natural phenolic compounds are usually polyhydroxy derivatives which exhibit hydrophilic capacity, limiting their applications directly in lipid systems. In this work, olive leaf phenolics (OLP) are extracted by ultrasound from five cultivars and the optimal cultivar is chosen to prepare W/O nano-emulsions of Sacha Inchi oil (SIO, containing more than 90% polyunsaturated fatty acids). The droplet size could reach 2.15 AE 0.13 nm and remains stable without phase separation during 30-day storage. Oxidative stabilities of SIO containing 0.02%, 0.05%, and 0.1% OLP (w/w) are evaluated by Rancimat test and accelerated storage test. The release of OLP by preparation of W/O nano-emulsions is capable of controlling the oxidative progress of SIO, by prolonging the induction time, preventing the production of primary and secondary oxidative products and also the deterioration of polyunsaturated fatty acids and tocopherols. Practical Applications: Sacha Inchi oil (SIO) contains approximately 90% of polyunsaturated fatty acids (PUFAs) associated with poor oxidative stability. Olive leaf phenolics (OLP) are considered as a great and cheap source of natural phenolic compounds. This study aimes to select the optimum source of OLP from five cultivars and to prepare a W/O nano-emulsion of OLP. By diluting the W/O nano-emulsion of OLP into SIO, effect of different concentrations OLP on the oxidative stability of SIO is evaluated through thermal oxidative stability and storage oxidative stability in an accelerated storage test. Results indicate that the capacity of OLP to retard the SIO oxidation depends on the incorporated concentration, which means that it is doable to adopt OLP, an abundant and cheap material, to improve the stability of edible oil with high PUFAs in the industry.

Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2018

α-amylase activity influences both flour fermentation process and the quality of the fermented pr... more α-amylase activity influences both flour fermentation process and the quality of the fermented products due to its ability of breaking starch into smaller units. The inhibition of cyclodextrins on α-amylase activity was investigated in this paper. Experiment results showed that hydrophobic cavity size was an intrinsic factor during the inhibition processing. Among three types of cyclodextrin (α-, β-and γ-), β-type exhibited the most significant inhibitory activity toward α-amylase. The optimal inhibitory parameters were indicated to be pH 5.9, concentration of β-cyclodextrins 1 mmol/L, reaction temperature 45 °C and reaction time 60 min. Results suggested that the endogenous fluorescence of α-amylase was inhibited by cyclodextrins. Circular dichroism spectrum indicated that the secondary structure of α-amylase, including α-helices, β-sheets and random coils, was changed by cyclodextrins. All the results in this paper aim to provide a further understanding for α-amylase in the industry application.

Journal of Agricultural and Food Chemistry, 2013

In this paper, aqueous extract fractions from byproducts of the processing of canned bamboo shoot... more In this paper, aqueous extract fractions from byproducts of the processing of canned bamboo shoots, including boiled water, filled liquid, and squeezed juice, were obtained by 5 kDa molecular cutoff membranes and marcoporous resin DA201-C treatment. The enriched bamboo shoot angiotensin converting enzyme (ACE) inhibitory peptide preparation fraction (called BSP for short) was extracted with ethyl acetate and n-butanol. The ethyl acetate fraction and n-butanol fraction exhibited higher antioxidant capacities than the leaving water fraction (BSML), which was attributed to the higher phenolic acid and flavonoid content of both fractions, while BSML exhibited the strongest ACE inhibitory activity. Sephadex G-15 gel filtration and semipreparative high-performance liquid chromatography were used for further purification of bamboo shoot ACE inhibitory peptide from BSML. Asp-Tyr was identified as the key active component by ultra-high-performance liquid chromatography and electrospray ionization tandem mass spectrometry. A short-term antihypertensive assay stated that both Asp-Tyr [10 mg day(-1) (kg of body weight)(-1)] and BSP [50 mg day(-1) (kg of body weight)(-1)] could significantly reduce the systolic blood pressure of spontaneously hypertensive rats (3-6 h). This study provides further examples of utilization of byproducts from the processing of canned bamboo shoots for the prevention of hypertension and attenuation of oxidative stress.

European Journal of Lipid Science and Technology, 2018

Natural phenolic compounds have been drawn a wide attention to replace the synthesis antioxidants... more Natural phenolic compounds have been drawn a wide attention to replace the synthesis antioxidants due to the food safety issues, while, natural phenolic compounds are usually polyhydroxy derivatives which exhibit hydrophilic capacity, limiting their applications directly in lipid systems. In this work, olive leaf phenolics (OLP) are extracted by ultrasound from five cultivars and the optimal cultivar is chosen to prepare W/O nano-emulsions of Sacha Inchi oil (SIO, containing more than 90% polyunsaturated fatty acids). The droplet size could reach 2.15 AE 0.13 nm and remains stable without phase separation during 30-day storage. Oxidative stabilities of SIO containing 0.02%, 0.05%, and 0.1% OLP (w/w) are evaluated by Rancimat test and accelerated storage test. The release of OLP by preparation of W/O nano-emulsions is capable of controlling the oxidative progress of SIO, by prolonging the induction time, preventing the production of primary and secondary oxidative products and also the deterioration of polyunsaturated fatty acids and tocopherols. Practical Applications: Sacha Inchi oil (SIO) contains approximately 90% of polyunsaturated fatty acids (PUFAs) associated with poor oxidative stability. Olive leaf phenolics (OLP) are considered as a great and cheap source of natural phenolic compounds. This study aimes to select the optimum source of OLP from five cultivars and to prepare a W/O nano-emulsion of OLP. By diluting the W/O nano-emulsion of OLP into SIO, effect of different concentrations OLP on the oxidative stability of SIO is evaluated through thermal oxidative stability and storage oxidative stability in an accelerated storage test. Results indicate that the capacity of OLP to retard the SIO oxidation depends on the incorporated concentration, which means that it is doable to adopt OLP, an abundant and cheap material, to improve the stability of edible oil with high PUFAs in the industry.

Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2018

α-amylase activity influences both flour fermentation process and the quality of the fermented pr... more α-amylase activity influences both flour fermentation process and the quality of the fermented products due to its ability of breaking starch into smaller units. The inhibition of cyclodextrins on α-amylase activity was investigated in this paper. Experiment results showed that hydrophobic cavity size was an intrinsic factor during the inhibition processing. Among three types of cyclodextrin (α-, β-and γ-), β-type exhibited the most significant inhibitory activity toward α-amylase. The optimal inhibitory parameters were indicated to be pH 5.9, concentration of β-cyclodextrins 1 mmol/L, reaction temperature 45 °C and reaction time 60 min. Results suggested that the endogenous fluorescence of α-amylase was inhibited by cyclodextrins. Circular dichroism spectrum indicated that the secondary structure of α-amylase, including α-helices, β-sheets and random coils, was changed by cyclodextrins. All the results in this paper aim to provide a further understanding for α-amylase in the industry application.

Journal of Agricultural and Food Chemistry, 2013

In this paper, aqueous extract fractions from byproducts of the processing of canned bamboo shoot... more In this paper, aqueous extract fractions from byproducts of the processing of canned bamboo shoots, including boiled water, filled liquid, and squeezed juice, were obtained by 5 kDa molecular cutoff membranes and marcoporous resin DA201-C treatment. The enriched bamboo shoot angiotensin converting enzyme (ACE) inhibitory peptide preparation fraction (called BSP for short) was extracted with ethyl acetate and n-butanol. The ethyl acetate fraction and n-butanol fraction exhibited higher antioxidant capacities than the leaving water fraction (BSML), which was attributed to the higher phenolic acid and flavonoid content of both fractions, while BSML exhibited the strongest ACE inhibitory activity. Sephadex G-15 gel filtration and semipreparative high-performance liquid chromatography were used for further purification of bamboo shoot ACE inhibitory peptide from BSML. Asp-Tyr was identified as the key active component by ultra-high-performance liquid chromatography and electrospray ionization tandem mass spectrometry. A short-term antihypertensive assay stated that both Asp-Tyr [10 mg day(-1) (kg of body weight)(-1)] and BSP [50 mg day(-1) (kg of body weight)(-1)] could significantly reduce the systolic blood pressure of spontaneously hypertensive rats (3-6 h). This study provides further examples of utilization of byproducts from the processing of canned bamboo shoots for the prevention of hypertension and attenuation of oxidative stress.