Peroxidase and polyphenol oxidase thermal inactivation by microwaves in green coconut water simulated solutions

Coconut water is a nutritious, natural, and refreshing drink. However, a challenge for the coconut water industry is its fast deterioration caused by naturally occurring enzymes mainly polyphenol oxidase (PPO) and peroxidase (POD). This study aimed to separate the PPO and POD using ultrafiltration and to evaluate its effect on the physicochemical properties and antioxidant attributes of tender and mature coconut water. The membrane used was polyethersulfone (PES) with two molecular weight cut-offs, namely 30 kDa (PES 30) and 50 kDa (PES 50) and conducted in a vacuum filter unit. The results showed that ultrafiltration with PES 30 completely separated the POD activity of both tender and mature coconut water. The ultrafiltration was also able to separate 86.07% PPO activity of tender coconut water and 100% separation on mature coconut water. While PES 50 could separate 49.60% PPO activity in tender coconut water. The ultrafiltration process also increased the clarity of mature coconut water and maintained the total sugar, sodium, and potassium contents in both maturities. However, ultrafiltration using these membrane types reduced total phenolic content and radical scavenging activity. In conclusion, this study revealed that ultrafiltration can remove the oxidative enzymes to extend the shelf life against oxidation deterioration. Further studies should be conducted to investigate the separation of enzymes without high significance loss of polyphenols, antioxidants, and nutritional properties

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Efficiency of coconut water immersion inhibiting browning incidence on cut-surface of fresh-cut ‘Gala’ apples during storage

MATEC Web of Conferences ◽

10.1051/matecconf/201819203004 ◽

2018 ◽

Vol 192 ◽

pp. 03004

Author(s):

Suriyan Supapvanich ◽

Dararat Anartnet ◽

Chutima Krungpree

Keyword(s):

Polyphenol Oxidase ◽

Water Immersion ◽

Coconut Water ◽

Total Phenols ◽

Colour Difference ◽

Browning Index ◽

Visual Appearance ◽

Significant Difference ◽

Fresh Cut ◽

Cut Surface

The purpose of the work was to investigate the efficiency of coconut water preventing browning incidence of fresh-cut product using ‘Gala’ apple as the fruit model. The fresh-cut apples were dipped in coconut water at the concentration of 0, 50 and 100% for 2 min and then kept at 4 ± 1 °C for 7 days. Browning-related parameters such as browning index (BI), browning score (BS), lightness (L*), whiteness index (WI), total colour difference (ΔE*), total phenols (TP), and polyphenol oxidase (PPO) activity were determined. The result showed that visual appearance of the fresh-cut apple was maintained by coconut water dip. Coconut water dip apparently lowered BI, BS and ΔE* increases and maintained L* and WI throughout the storage. The increases in TP and PPO activity of the fresh-cut apples were inhibited by coconut water dips. No significant difference in browning prevention efficiency of the both 50 and 100% coconut water dips was found. Thus 50% coconut water dip is an effectively natural alternative preventing browning incidence of fresh-cut products.

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