Effect of pH, temperature and some chemicals on polyphenoloxidase and peroxidase activities in harvested Deglet Nour and Ghars dates

Amiour, Saliha Daas; Hambaba, Leila

doi:10.1016/j.postharvbio.2015.07.027

Cited by 26 publications

(17 citation statements)

References 29 publications

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“…The action of PPO and POD in browning has been reported in literature for many fruits, but very little attention has been given to dates. Therefore, there are very limited reports that talk on enzymatic oxidation of polyphenols in dates during ripening and storage [5,6,12,13].…”

Section: Introductionmentioning

confidence: 99%

Assessment of Enzymatic Browning and Evaluation of Antibrowning Methods on Dates

Al-Amrani

Al‐Alawi

Al-Marhobi

2020

International Journal of Food Science

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Dates’ color is known to play a crucial role in determining the value and quality of the fruit. The color changes from the natural accepted golden color to unfavorable dark brown color during storage. In this study, the effect of different color preservation methods (modified atmosphere packaging, cold storage (4°C), sulfur dioxide gas (SO2), and blanching) and its relation to darkening due to action of the browning enzymes and melanin production were investigated. Polyphenol oxidase was shown to be active in all treatments except the samples treated with SO2 gas and steam blanching for ten minutes. Likewise, peroxidase activity showed a similar trend in all samples, but a decrease in activity was observed in sulfated samples and total inactivation in steam blanching for ten minutes. Moreover, sulfated samples have shown improvement in color compared to all other treatments, whereas the steamed samples showed the highest color deterioration. Concurrently, melanin content increased in all samples over the period of storage except in the sulfated samples. FTIR analyses of dates’ melanin have revealed similar structural feature to the reference melanin; however, some differences were noticed in the regions 2850–2950 cm-1 and 1690–1705 cm-1 which indicated major structural difference between the two melanin samples. More work is suggested to reveal structural and functional properties of dates’ melanin.

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Section: Introductionmentioning

confidence: 99%

Assessment of Enzymatic Browning and Evaluation of Antibrowning Methods on Dates

Al-Amrani

Al‐Alawi

Al-Marhobi

2020

International Journal of Food Science

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“…The unequal partitioning of H + and OH − concentrations in the microenvironment of the immobilized enzyme, due to electrostatic interactions with the support, can induce changes in the optimum pH [57]. The reduction of the enzymatic activity observed at extreme pHs has possibly occurred by the denaturation of enzymes by ionization [58].…”

Section: Effect Of Phmentioning

confidence: 99%

Immobilization of Low-Cost Alternative Vegetable Peroxidase (Raphanus sativus L. peroxidase): Choice of Support/Technique and Characterization

et al. 2020

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In the present work the radish (Raphanus sativus L.) was used as the low-cost alternative source of peroxidase. The enzyme was immobilized in different supports: coconut fiber (CF), calcium alginate microspheres (CAMs) and silica SBA-15/albumin hybrid (HB). Physical adsorption (PA) and covalent binding (CB) as immobilization techniques were evaluated. Immobilized biocatalysts (IBs) obtained were physicochemical and morphologically characterized by SEM, FTIR and TGA. Also, optimum pH/temperature and operational stability were determined. For all supports, the immobilization by covalent binding provided the higher immobilization efficiencies—immobilization yield (IY%) of 89.99 ± 0.38% and 77.74 ± 0.42% for HB and CF, respectively. For CAMs the activity recovery (AR) was of 11.83 ± 0.68%. All IBs showed optimum pH at 6.0. Regarding optimum temperature of the biocatalysts, HB-CB and CAM-CB maintained the original optimum temperature of the free enzyme (40 °C). HB-CB showed higher operational stability, maintaining around 65% of the initial activity after four consecutive cycles. SEM, FTIR and TGA results suggest the enzyme presence on the IBs. Radish peroxidase immobilized on HB support by covalent binding is promising in future biotechnological applications.

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“…The differences between our results and those in the literature can be attributed to the geographical origin of the fruits (Al Harthi et al, 2015), the extraction method. In addition, solvent could be at the origin of the variations in the phenolic compounds of the date extract Shahdadi et al, 2015;Amiour and Hambaba, 2016;Mrabet et al, 2016).…”

Section: Flavonols and Flavonesmentioning

confidence: 99%

RP-HPLC-PDA-ESI-MS/MS screening of bioactive compounds from Degla-Beida dates: Conventional and green extraction technologies

Djaoud

Daglia

Sokeng

et al. 2020

Ann.UDJG.FoodTechnology

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Date fruits have vital therapeutic properties, in the way that they represent an inexhaustible source of bioactive compounds such as polyphenols. Therefore, the objective of this work was to evaluate the phytocomposition by High Performance Liquid Chromatography (RP-HPLC-PAD-ESI-MS/MS) of the optimized microwaveassisted extraction (MAE) phenolic extract by using the response surface methodology (RSM) compared to the ultrasound-assisted and conventional extractions (UAE and CE), and to test its antioxidant activity in vitro. The resulting regression model indicated that a quadratic polynomial model was best suited for the spectrophotometrically determined total phenolics. The maximum total phenolic content, TPC, (4.27±0.09 mg GAE/g DW) was obtained with a 50% (v/v) ethanol's concentration, a 700 W microwave power and an extraction time of 2.42 minutes. HPLC analysis revealed the presence of organic sugars and acids, nucleoside, carotenoids, proanthocyanidins, lignans, flavonols, flavones, saponin and sterol glucosides. The MAE phenolic extract showed 58.72±0.29% DPPH radical scavenging activity and a 1.88±0.09 mg AscAE/mL reducing power.

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Effect of pH, temperature and some chemicals on polyphenoloxidase and peroxidase activities in harvested Deglet Nour and Ghars dates

Cited by 26 publications

References 29 publications

Assessment of Enzymatic Browning and Evaluation of Antibrowning Methods on Dates

Assessment of Enzymatic Browning and Evaluation of Antibrowning Methods on Dates

Immobilization of Low-Cost Alternative Vegetable Peroxidase (Raphanus sativus L. peroxidase): Choice of Support/Technique and Characterization

RP-HPLC-PDA-ESI-MS/MS screening of bioactive compounds from Degla-Beida dates: Conventional and green extraction technologies

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