Comparative evaluation of retort pouch packaging and pulsed light technology for the preservation of coconut - Neera

Abstract

Coconut-neera is the sweet, honey-coloured vascular sap extracted from the inflorescence of the coconut palm. This phloem sap “Neera” is low in glycemic index and rich in bioactive components and sugar. The main problem associated with this nutritional drink is its rapid fermentation within a few hours of extraction. Hence the commercialisation of coconut-neera is not possible without processing. The present study envisages the comparative evaluation of retort pouch packaging and pulsed light technology for the preservation of this wholesome drink coconut-neera. Retort processing is the innovative and widely accepted method of thermal processing which is used for the preservation of various processed food products nowadays. Pulsed UV light processing is one of the very innovative and advanced non-thermal processing technologies which is effective for surface decontamination of solid foods and decontamination of transparent liquid foods. In this study, an attempt was made to optimise the process parameters and evaluate the safety and quality of the optimally processed sample. Retort processing of neera was performed at temperature (70 to 90°C) and time (15 to 25 min) and pulsed light processing of the samples at the number of pulses (50 to 150), depth of the sample (5 to 15 mm) and sample source distance (4 to 10 cm). The optimization of process variables involved in retort processing and PL processing was done using Central Composite Design (CCD) and Box-Behnken Design (BBD) of response surface methodology respectively. The best results were obtained at 82°C for 19 min in retort processing and at 150 number of pulses, 5 mm depth of the sample, and 7 cm sample-source distance in PL processing. Samples processed under optimum conditions were evaluated for sensory quality and the retort processed samples maintained better sensory quality compared to PL processed samples. The rheological characteristics of fresh, retort and pulsed light processed neera showed non-Newtonian shear thickening behavior. The shelf life study of the samples 173 processed at optimised conditions revealed that the retort process and PL process could provide a shelf life of 25 and 20 days, respectively under refrigerated conditions retaining their physico-chemical characteristics and microbial level at a safe limit.