The effect of citric acid on the activity, thermodynamics and conformation of mushroom polyphenoloxidase

Liu, Wei; Zou, Liqiang; Liu, Junping; Zhao-qin, Zhang; Liang, Ruihong

doi:10.1016/j.foodchem.2013.02.028

Cited by 54 publications

(35 citation statements)

References 29 publications

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“…Citric acid, whose concentration in M1 (78.1 ± 10.8 mmol/L) and M2 (73.6 ± 0.4 mmol/L) were higher than that in B1 (56.5 ± 0.1 mmol/L) and B2 (62.9 ± 0.4 mmol/L), is the main acidulant widely used in the agro‐food industry. The inhibition of CA was mainly attributed to its capability of reducing the pH in the medium and consequently decreasing the enzyme activity (Liu et al ).…”

Section: Resultsmentioning

confidence: 99%

Evaluation of antibrowning and antioxidant activities in unripe grapes recovered during bunch thinning

Tinello

Lante

2016

Australian Journal of Grape and Wine Research

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Background and Aims: Research into new systems for controlling enzymatic browning in the agro-food industry has been focused on eco-friendly alternatives to conventional thermal treatments and traditional additives, which could impair the sensory, nutritional and health properties. The use of unripe grapes for reducing alcohol concentration and pH of wines has been previously reported; however, no studies have been made of the evaluation of unripe grapes as potential functional ingredients to control enzymatic browning and to enhance antioxidant properties of plant products. Methods and Results: Unripe berries were collected in two seasons during bunch thinning of Barbera and Merlot vineyards. Merlot grapes, which had the highest antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl and ferric reducing ability of plasma assays, were also the most effective in preventing enzyme browning, as confirmed by spectrophotometric assays using commercial mushroom tyrosinase, by zymographic techniques on the isoforms isolated from some plant polyphenol oxidases and by in vivo trials on fresh-cut fruits and vegetables. Conclusions: The juice of unripe grapes showed not only antibrowning but also antioxidant and whitening activities. Significance: Unripe grapes discarded during bunch thinning of vineyards represent for the agro-food industry a significant source of bioactive compounds that are easy to produce and safe for human health, thus converting these agricultural wastes into value-added products.

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Section: Resultsmentioning

confidence: 99%

Evaluation of antibrowning and antioxidant activities in unripe grapes recovered during bunch thinning

Tinello

Lante

2016

Australian Journal of Grape and Wine Research

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“…Similarly, Liu et al found a decrease of fluorescence intensity and a red shift in maximum emission wavelength, indicating that the activity of PPO in mushroom gradually decreased till an inactive state. [16] These results indicated that the tertiary structural of PPO gradually changed as the temperature increases. The red shift could indicate the variations in the three-dimensional structures (secondary, tertiary, and quaternary structures) or the conformation of the enzymes.…”

Section: Thermal Treatment Of Ppomentioning

confidence: 89%

“…Spectroscopy is an effective way to study the conformation of the protein and its microscopic characteristics. [16] In this study, PPO from Penaeus vannamei was purified and characterised in terms of optimum pH and temperature. Thermal stability of the enzyme, along with the secondary and tertiary structural characteristics induced by thermal inactivation, was determined in an effort to explore the mechanism of thermal inactivation of PPO from Penaeus vannamei.…”

Section: Introductionmentioning

confidence: 99%

Purification, characterisation, and thermal denaturation of polyphenoloxidase from prawns (Penaeus vannamei)

Cai

Yang

et al. 2017

International Journal of Food Properties

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Polyphenoloxidase (PPO) from prawns (Penaeus vannamei) was purified by ammonium sulphate precipitation, ion-exchange column, and gel filtration chromatography. The specific activity of PPO increased by 9.51 fold to 575.03 U/mg, and the molecular weight of PPO was 66 kDa. The optimal temperature and pH were around 45°C and 6.8, determined by L-β-(3,4dihydroxylphenyl) alanine (L-DOPA) as substrate. K m and V max values were found to be 2.5 mM and 0.062ΔA/min. The effect of thermal treatment on the activity, conformation, and microstructure of the PPO was investigated. Thermal stability of PPO was measured at 40°C, 50°C, 60°C, 70°C, and 80°C, and the half-life values of PPO were 105, 39.6, 13.4, 8.9, and 3.1 min, respectively. PPO activity slightly decreased at 60°C, while the relative enzyme activity remained 9.4% after 80°C for 10 min. The result of differential scanning calorimetry showed that the denatured temperature of PPO was 65°C. Thermal treatment resulted in the changes in the tertiary structure of PPO, and the λ max of fluorescence spectra was red-shifted with decreasing intensity. Curve-fitting analysis showed that α-helix and β-sheet decreased, but β-turns and random coil increased with increased temperature. Atomic force microscopy revealed that PPO molecules aggregated remarkably at 60°C. Moreover, the formation of large globular aggregates occurred as the temperature increased.

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“…BA (QI et al 2009) and CA (LIU et al 2013) have been widely used in the food industry as an important food preservative. However, they cause some adverse effects on animals (YILMAZ et al 2008;QI et al 2009).…”

Section: Discussionmentioning

confidence: 99%

<I>In Vitro</I> Effects of Quercetin on Oxidative Stress Mediated in Human Erythrocytes by Benzoic Acid and Citric Acid

Baş¹,

Kalender²,

Pandır³

2014

folia biol (krakow)

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Benzoic acid (BA) and citric acid (CA) are food additives commonly used in many food products. Food additives play an important role in food supply but they can cause various harmful effects. The in vitro adverse effects of BA and CA and the protective effect of quercetin on human erythrocytes were investigated by measuring malondialdehyde (MDA) levels and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities. Erythrocytes were incubated with BA and CA, at three doses of 50, 100 and 200 microg/ml, and quercetin, at a concentration of 10 microM. After BA and CA application, a dose-dependent increase in MDA level and decreases in SOD, CAT, GST and GPx activities were found in erythrocytes. Among the two food additives, BA exerted a more harmful influence on human erythrocytes than CA. The protective effects of quercetin against oxidative stress--induction in the human erythrocytes by CA and BA, were found when these two food additives were applied at each of three doses of 50, 100 and 200 microg/ml. However, complete protection of quercetin against CA toxicity was only observed when this agent was applied at a lower dose of 50 microg/ml. Quercetin did not completely protect erythrocytes even at the lowest concentration of BA.

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The effect of citric acid on the activity, thermodynamics and conformation of mushroom polyphenoloxidase

Cited by 54 publications

References 29 publications

Evaluation of antibrowning and antioxidant activities in unripe grapes recovered during bunch thinning

Evaluation of antibrowning and antioxidant activities in unripe grapes recovered during bunch thinning

Purification, characterisation, and thermal denaturation of polyphenoloxidase from prawns (Penaeus vannamei)

<I>In Vitro</I> Effects of Quercetin on Oxidative Stress Mediated in Human Erythrocytes by Benzoic Acid and Citric Acid

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