Formulation, characterisation and antibacterial activity of lemon myrtle and anise myrtle essential oil in water nanoemulsion

This study focussed on the formulation, characterisation of lemon myrtle (LM) and anise myrtle (AM) essential oil (EO) in water nanoemulsion and their antibacterial activity. The required hydrophilic lipophilic balance (rHLB) value of LM EO and AM EO was 14 and 12, respectively. The Central Composite Rotatable Design (CCRD) model produces the smallest droplet size and polydispersity index (PDI) for LMEO (d ≈ 16.07 nm; PDI ≈ 0.209) and AMEO (d ≈ 30.23 nm; PDI ≈ 0.216) at 1% EO and 10% surfactant mixture (Smix) ratio using ultrasonication for 5 min. Whereas, increased in EO, decrease in Smix concentrations and ultrasonication time produces higher droplet size of nanoemulsions. LMEO (LM-15, LM-17) nanoemulsions was clear and transparent compared to AMEO (AM-15, AM-17). All the selected nanoemulsions showed good stability at 4, 25 and 40 °C during storage, except LM-15 at 40 °C. LMEO nanoemulsion showed enhanced antibacterial activity compared to LMEO alone (P

Inhibition of Polyphenoloxidase and Melanosis in Pacific White Shrimp (Litopenaeus vannamei) by Phenolic Compounds

Thesis (Ph.D., Food Science and Technology)--Prince of Songkla University, 201

Use of tea extracts for inhibition of polyphenoloxidase and retardation of quality loss of Pacific white shrimp during iced storage

Green tea and mulberry tea powder with and without prior chlorophyll removal were extracted with water and ethanol (800 mL L-1). Extraction yield and total phenolic content of green tea extract were higher than those of mulberry tea extract, regardless of extraction media (P 0.05). Furthermore, ethanolic green tea extract with prior chlorophyll removal had no adverse impact on sensory attributes of treated shrimp

Inhibitory effect of mimosine on polyphenoloxidase from cephalothoraxes of pacific white shrimp (Litopenaeus vannamei)

The inhibitory effect of mimosine on polyphenoloxidase (PPO) from the cephalothorax of Pacific white shrimp (Litopenaeus vannamei) was studied. Mimosine showed inhibitory activity toward PPO from white shrimp with an apparent molecular weight of 210 kDa as evidenced by the decrease in the activity staining band, as compared to the control. An inhibition kinetic study revealed that mimosine exhibited the mixed type reversible inhibition on PPO from white shrimp with a K i value of 3.7 mM. Mimosine showed copper (Cu 2+) reduction and chelating capacity in a dose dependent manner. Mimosine could react with the intermediate browning product, thereby rendering lower red-brown color formation. Therefore, mimosine could inhibit PPO by different modes of inhibition and could be used to prevent melanosis formation in Pacific white shrimp

Retardation of quality changes of Pacific white shrimp by green tea extract treatment and modified atmosphere packaging during refrigerated storage

The effect of modified atmosphere packaging (MAP) on the quality changes of Pacific white shrimp (Litopenaeus vannamei) treated with or without green tea extract (1g/L; GTE) in combination with or without ascorbic acid (0.05g/L; AA) during refrigerated storage of 10days was investigated. Shrimp without treatment stored under MAP had lowered psychrotrophic bacteria, enterobacteriaceae and H2S-producing bacteria count (P0.05), in comparison with shrimp stored in air (control). The coincidental lowered rate of increase in pH, total volatile base (TVB) content and thiobarbituric acid reactive substances (TBARS) were obtained in shrimp stored under MAP (

Melanosis and quality changes of Pacific white shrimp (Litopenaeus vannamei) treated with catechin during iced storage

Melanosis, microbiological, chemical, and physical changes of Pacific white shrimp (Litopenaeus vannamei) treated with catechin were monitored during iced storage of 10 days. Whole shrimp treated with catechin solution (0.05 or 0.1%) had retarded growth of psychrophilic bacteria and spoilage microorganisms including H2S-producing bacteria and enterobacteriaceae throughout storage in comparison with the control and those treated with 1.25% sodium metabisilfite (SMS) (P < 0.05). The lower increases in pH and total volatile base (TVB) content were obtained in the shrimp treated with catechin solution at both levels, compared with those of other samples (P < 0.05). Lipid oxidation, loss in freshness and melanosis were lowered by catechin treatment. In general, the efficacy of catechin in lowering melanosis and quality losses increased with increasing levels used. Additionally, catechin (0.01, 0.05, and 0.1% (w/v)) showed inhibitory activity toward polyphenoloxidase (PPO) of Pacific white shrimp in a dose-dependent manner. Therefore, catechin can be used as a promising melanosis inhibitor as well as an antimicrobial and an antioxidant in ice-stored shrimp

Inhibition kinetics of catechin and ferulic acid on polyphenoloxidase from cephalothorax of Pacific white shrimp (Litopenaeus vannamei)

Inhibition kinetics and mode of catechin and ferulic acid towards polyphenoloxidase (PPO) from cephalothorax of Pacific white shrimp were investigated. Catechin or ferulic acid inhibited quinone formation catalysed by PPO in a dose dependent manner. Catechin showed mixed type reversible inhibition with Ki value of 1.4 mM, whereas ferulic acid exhibited non-competitive reversible inhibition with Ki value of 37 mM. With increasing concentrations, both catechin and ferulic acid had higher copper (Cu2+) reduction and copper chelating capacity (P < 0.05). Catechin or ferulic acid could react with intermediated browning reaction products, thereby preventing dopachrome formation. Thus, catechin or ferulic acid could inhibit melanosis in Pacific white shrimp with different modes of inhibition towards PPO

Antioxidant, antibacterial, and anti-inflammatory activities of standardized brazilin-rich Caesalpinia sappan extract

Context: Brazilin is a major active principle of Caesalpinia sappan L. (Leguminosae or Fabaceae). For industry aspects, brazilin-rich extract (BRE) has been prepared and standardized to contain 39% w/w brazilin. BRE may have more advantages than brazilin in term of a lower-cost production process. Objectives: To investigate the antioxidant, antibacterial, and anti-inflammatory activities of BRE. Material and methods: BRE was prepared by a simple one-step purification of the crude ethanol extract of C. sappan heartwood (CSE) using a Diaion® HP-20 column. The antioxidant activities were determined using three methods, including DPPH radical scavenging, reducing power, and β-carotene bleaching assays, at concentration ranges of 1-10, 10-100, and 10-100μg/mL, respectively. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of BRE (15.6-1000μg/mL) against Gram-positive and Gram-negative bacteria were determined by the broth microdilution method. Anti-inflammatory activity of BRE (0.1-5μg/mL) was evaluated as anti-denaturation activity using bovine serum albumin as a substrate. Results and discussion: On the basis of β-carotene bleaching assay, BRE showed antioxidant activity with an EC50 value of 60.5μg/mL, which was almost equal to that of pure brazilin (52.1μg/mL). Gram-positive bacteria were more sensitive to all tested samples than Gram-negative bacteria. BRE possessed higher antibacterial activities than CSE, but lower than brazilin. MIC/MBC values of 62.5-125/125 and 250-500/250-500μg/mL were obtained for BRE against Gram-positive and Gram-negative bacteria, respectively. A low concentration (0.1μg/mL) of brazilin, BRE, and CSE showed anti-inflammatory activity by inhibiting protein denaturation up to 46.8, 54.1, and 61.9%, respectively