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Abstract The spoilage enzymes in tender coconut water were inactivated by atmospheric cold plasma technology. The kinetics of peroxidase (POD) and polyphenol oxidase (PPO) inactivation was studied at voltage levels varying between 18 and 28 kV dielectric barrier discharge plasma treatments (DBD) at atmospheric air. The time of treatment and applied voltage were significant factors for inactivation of the enzymes. POD was more resistant than PPO. The experimentally observed data were fitted to establish different kinetics models and model parameters were evaluated. The sigmoidal logistic was the best fitting model to explain the kinetics of browning enzymes inactivation based on high RMSE values. The time required for half maximal activity values for POD was 0.84, 1.67 and 2.53 min at 18 kV, 23 kV and 28 kV, respectively which was higher than PPO with half maximal activity values of 0.67, 1.18 and 1.35 min, respectively. This indicates that POD is more resistant to cold plasma than PPO and its inactivation in tender coconut water by cold plasma can be considered as a crucial quality parameter. DBD generated cold plasma can therefore be used to process fruits and vegetables juices wherein enzymes activity is one of the quality deterioration parameters. Highlights • DBD cold plasma used to inactivate POD and PPO in tender coconut water. • Treatment time and applied voltage showed significant inactivation. • POD was more resistant than PPO to DBD cold plasma. • Sigmoidal shaped Logistic model adequately described the enzymes inhibition. • DBD cold plasma can be used as a quality indicator for enzymatically spoiled foods. [ABSTRACT FROM AUTHOR]

Non-thermal two-stage microfiltration technique in aseptic conditions was used to preserve coconut water. Concentrations of citric acid (0.02 g/100 mL), ascorbic acid (0.18 g/100 mL) and l -cysteine (0.009 g/100 mL) were standardized according to taste and added to coconut water as natural additives. The coconut water was packed in glass and plastic bottles after flushing the headspace with nitrogen and stored under refrigeration (4 °C). The microfiltered water was studied for microbial, sensory and physicochemical properties for a period of 46 days. The quality of the water packed in glass bottles was better in all respects. The total soluble solids changed from 5.4 to 6 °Brix. The pH changed from 5.7 to 5.8. The soluble sugar concentration increased from 1.9 g/100 mL to 3.1 g/100 mL, free fatty acid content increased from 0.064 mg KOH/g to 2.8 mg KOH/g at the end of 46 days, which was much lower than the changes in control. The protein content decreased in all the samples. Two way ANOVA showed that the storage time had more impact on the sensory properties of the product than the packaging material. The glass bottled product was acceptable on sensory basis till 46 days of storage. [ABSTRACT FROM AUTHOR]

Abstract: Coconut water was processed through 2-stage microfiltration system and l-ascorbic acid (25mg/100ml) was added to it, and then stored at 4°C for 28days. Micro-filtered coconut water, added (AS) or without added (US) ascorbic acid was analyzed for physicochemical, sensorial and microbial changes. With increase in storage time perpetual decrease in nutritional values and sensory qualities of the samples occurred; nevertheless, AS was able to retain these qualities more than US. Added ascorbic acid delayed the decrease of clarity (% transmittance) (p <0.05), sensory qualities, and also slowed down the increase of reducing sugar and total fatty acids. A kinetic study of post processing quality loss was also conducted during the storage period. Adequacy of zero and first order kinetic models were dependent on the specific quality attributes that were studied. Principal Component Analysis (PCA) clearly showed that more drastic color and sensory changes occurred in US compared to AS. Industrial relevance: Recently, microfiltration of coconut water has been found to be an alternative to thermal sterilization. This study was undertaken to evaluate the effect of l-ascorbic acid addition on the quality attributes of micro-filtered coconut water during low temperature storage (4°C for 28days). The study makes a reasonable comparison of the quality attributes of micro-filtered coconut water, with or without added ascorbic acid. Concerted effect of microfiltration and l-ascorbic acid addition proved to be a better method for processing coconut water than microfiltration alone. [Copyright &y& Elsevier]

Abstract: Coconut water was processed through 2-stage microfiltration system and L-ascorbic acid (25mg/100ml) 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 21days 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 1H 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. [Copyright &y& Elsevier]