Stability of selected quality attributes of pink guava juice during storage at elevated temperatures

Headnote

Article history

Received: 15 August 2015

Received in revised form: 22 December 2015

Accepted: 6 January 2016

Keywords

Quality degradation

Pink guava juice

Kinetic

Activation energy

Q10

Abstract

Quality degradation is normally judge by monitoring independently the loss of a certain quality attribute during storage. However, the rate of degradation for each of the quality attributes present in a food product is not the same. This study focus on deterioration of vitamin C, lycopene, total phenolics and antioxidant activity of ready-to-drink pink guava juice (PGJ) during storage at elevated temperatures. Kinetic order, rate constant (k), activation energy (Ea) and temperature coefficient (Q10) of the degradation were derived by applying Arrhenius equation. The results obtained showed that freshly made PGJ contain 39.79±2.18 mg/100 mL of vitamin C, 3.17±0.27 mg/L of lycopene, 28.08±4.11 mgGAE/100 mL of total phenolic content (TPC) and 13.20±1.91 mMTE/100 mL of ferric reducing antioxidant power (FRAP). All quality attributes measured in this study showed zero-order kinetic reaction. The results also showed that FRAP has the highest Ea of 49.52 KJ/mol and Q10 of 1.80, followed by vitamin C (Ea=41.49 KJ/mol; Q10=1.64), lycopene (Ea=31.75 KJ/mol; Q10=1.46), and lastly TPC (Ea=14.11 KJ/mol; Q10=1.18). The predicted total depletion of each quality attribute at refrigerated storage (5°C) were 266 days for antioxidant activity, 158 days for vitamin C and lycopene, and 63 days for total phenolics. This study provide useful information on the degradation rate and availability of health beneficial and bioactive compounds present in fruit juice beverage during storage.

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Introduction

Guava (Psidium guajava L.) belongs to the Myrtaceae family, originated in the American tropics and is today distributed throughout the tropical and subtropical areas of the world. Guava can be classified into white and pink guava based on the colour of its flesh. The largest pink guava plantation in the world with over 500 hectares of guava fruit grown is located in Sitiawan, Perak, followed by Johor; both in Malaysia. Both white and pink flesh guava fruits are aromatic, rich in minerals and vitamins. Vitamin C content in guava fruit is known to be significantly higher than most citruses. This vitamin is an important nutrient known for its antioxidant and anticancer properties, and other health promoting...