Effects of L-ascorbic acid addition on micro-filtered coconut water: Preliminary quality prediction study using 1H-NMR, FTIR and GC-MS

Abstract Coconut water was processed through 2-stage microfiltration system and L-ascorbic acid (25 mg/100 ml) was added to it, and then stored at 4 °C. Micro-filtered coconut water, with (AS) or without (US) added ascorbic acid was analyzed on 0 and 21 days of storage, using 1 H-NMR, FTIR and GC-MS. The spectral analyses revealed that the addition of L-ascorbic acid to micro-filtered coconut water was able to retain methyl-α-D-rhamnopyranoside (prime glycoside detected in micro-filtered coconut water) better in AS than US, and also controlled the formation of free fatty acids and delayed rancidity in AS. Good correlation was found between these spectral results. PCA for both FTIR and 1 H-NMR data sets presented the separation of fresh and stored micro-filtered coconut water samples. While still in the early stages of investigation, this work showed the potentiality of 1 H-NMR, FTIR and GC-MS tools for monitoring the changes in micro-filtered coconut water. Industrial relevance Recently, microfiltration of coconut water has been found to be an alternative to thermal sterilization. A preliminary study was undertaken to study the effect of addition of L-ascorbic acid on the quality of micro-filtered coconut water, by using 1 H NMR, FTIR and GC-MS, mainly to detect the tentative chemical changes occurring in it during low temperature storage (4 °C for 21 days). High correlation was found between the results of these instrumental methods, the use of which can be used as key determinants for assessing the quality of such processed coconut water during routine inspection and also in further in-depth research.