Impact of Nonthermal Pulsed Electric Field on Bioactive Compounds and Browning Activity in Emblica officinalis Juice

The effect of nonthermal pulsed electric field (PEF) and thermal treatment (90⁰C for 60s) was studied on quality parameters of Emblica officinalis juice for the period of 6 weeks at 4⁰C using monopolar rectangular pulse of 1µs width. The PEF treatment was given using static chamber at 24kV/cm for 500µs. The quality of Emblica officinalis juice was investigated in terms of non enzymatic browning index (NEBI), 5-hydroxymethyl-2-furfural (HMF), total polyphenol content and antioxidant capacity. ⁰Brix, pH and conductivity were evaluated as physical parameters. The aim of the work was to investigate the effect of PEF on the retention of bioactive compounds and retardation of browning activity. The results showed that conventional thermal treatment had led to a significant (p<0.05) decrease of 48.15% in polyphenol content (129.56 mg of GAE L-1), with higher NEBI and HMF formation (p < 0.05) whilst PEF suppressed NEBI and retained higher polyphenol compounds (168.59mg GAE L-1) with limiting the loss to 32.56% along maximum free radical scavenging activity (92.07%). However, pH, ⁰brix and electrical conductivity of treated juice samples remain unaffected. Therefore, PEF can be considered as an effective nonthermal treatment for retaining bioactive compounds along suppressing browning of emblica juice

Coupling of chromatographic analyses with pretreatment for the determination of bioactive compounds in Emblica officinalis juice.

A simple and new method for the simultaneous detection and quantification of vitamin C (ascorbic acid), phenolic acids (gallic acid and ellagic acid), hydroxycinnamic acid (chlorogenic acid) and flavonoids (myricetin, quercetin and kaempferol) in Emblica juice is developed. The compounds are separated in 18 minutes by an intangible curved gradient of 0.1% ortho-phosphoric acid in water (v/v) and acetonitrile, as mobile phase A and B, respectively, using Zorbax SB RP C-18 column at a wavelength of 254 nm. The assay was optimized by varying the mobile phase, gradient type, pretreatment method (thermal and non-thermal) and detection wavelength. The method was validated in terms of linearity, precision, detection limits and quantification limits. Good linear response was observed over the range specified for all the analytes, as confirmed by the correlation coefficient which ranged from 0.991 and 0.995. The limit of detection (LOD) and limit of quantification (LOQ) were found to be in the range of 0.129–0.685 μg ml−1 and 0.43–2.883 μg ml−1 respectively. Pulsed electric field (PEF) was used as the non-thermal pretreatment sample technique. HPLC-PDA showed increased levels of phenolic acids, as gallic and ellagic acid, and flavonoid, as quercetin, in PEF treated Emblica juice with respect to the untreated and thermally treated juice samples (p < 0.05). The overall precision values obtained for standards and samples were within the range 0.01–0.2 and 0.15–0.23 respectively. Further, total polyphenolic content and free radical scavenging capacity of the untreated, thermally and PEF treated Emblica juice were corroborated by HPLC

Rapid HPLC method development for determination of vitamin C, phenolic acids, hydroxycinnamic acids, and flavonoids in Emblica officinalis juice

The work proposes a simple method for simultaneous detection and quantification of vitamin C (ascorbic acid), phenolic acids (gallic acid and ellagic acid), hydroxycinnamic acid (chlorogenic acid), and flavonoids (myricetin, quercetin, and kaempferol) in seasonal samples of emblica juice. The compounds were separated by an intangible curved gradient of 0.1% orthophosphoric acid in water (v/v) and acetonitrile as mobile phase A and B using Zorbax SB RP C-18 column at a wavelength of 254 nm in 18 min. The assay was optimized by varying the mobile phase, gradient type, and detection wavelength. The method was validated in terms of linearity, precision, detection limits, and quantification limits. Good linear response was observed over the range specified for all the analytes, as confirmed by the correlation coefficient which ranged from 0.991 and 0.995. The limit of detection and limit of quantification were found to be in the range of 0.129–0.685 µg mL−1 and 0.43–2.883 µg mL−1, respectively. Complete resolution of the phenolic compounds was achieved without the need of pre-analysis processes. The overall precision values obtained for standards and samples were within the range of 0.01–0.2 and 0.15–0.23, respectively

Optimization and characterization of pulsed electric field parameters for extraction of quercetin and ellagic acid in emblica officinalis juice

A novel study has been optimized for the application of pulsed electric field (PEF) treatment (varying from 18 to 24 kV cm−1 for the duration 300–1,000 µs) on fresh emblica juice for extracting quercetin & ellagic acid which are considered as the major secondary metabolites in plant based foods. HPLC–PDA studies showed substantial increase (p < 0.05) in the PEF extracted levels of above metabolites in herb juice. It can be attributed to PEF induced vibrational disruption which increases the metabolic stress leading to emergence of these compounds. Both Raman and FTIR characterization, confirmed the presence of these in emblica juice. Electric field strength of 22 kV cm−1 was found to be optimum, where maximum cell disintegration index (0.79) was achieved during treatment time of 500 µs, which enhanced the amount of quercetin to about ninefolds and ellagic acid to about twofolds respectively, in comparison to untreated and thermally treated juice sample. However, a reverse trend was observed in thermally treated juice where degradation of the compounds (p < 0.05) was detected. Thus, PEF can be considered as a viable medium for extracting intracellular metabolites, thereby incrementing the functional potential of emblica juice

Synthesis and energy applications of metal organic frameworks

The unique and tunable properties of metal organic framework (MOF) provide a new technological opportunity to challenge various issues in energy sectors. This review critically assesses the unique features regarding the synthesis methods of MOFs and discusses their vigorous role in light emitting device and photovoltaic devices. This review article also aims to help upgrade the feasibility of MOFs for the future applications towards energy systems and to provide an outline for the future opportunities in this field

Influence of pulsed electric field and heat treatment on Emblica officinalis juice inoculated with Zygosaccharomyces bailii

The effects of pulsed electric field (PEF) applying 26 kV cm−1 with 1 μs monopolar pulses (for 500 μs) on inactivation of Zygosaccharomyces bailii and the stability for the key quality characteristics (vitamin C, phenolic content, antioxidant capacity, nonenzymatic index, 5-hydroxymethyl-2-furfural (HMF), °brix, and pH) in Emblica officinalis juice were studied. These results were then compared to those of heat treatment (90 °C for 60 s) up to 40 days on storing at 4 °C. PEF treatment reduced 5.1 log cycles of Z. bailii with decreases in HMF concentration and browning index relative to heat treated juice. Simultaneously, PEF treated juice retained 63% of vitamin C and 88.9% of antioxidant capacity (p < 0.05). However, heat treated juice lowered 4.9 log cycles of Z. bailii and exhibited significant degradation of vitamin C and antioxidant capacity (p < 0.01). After all, both treatments did not induce any major changes in pH and °brix levels of emblica juice. Electron microscopy was used as a tool to find Z. bailii damage induced. Investigation of their morphology showed a leakage of cellular debris owing to the rupture of cell membrane of PEF treated Z. bailii. Thus, PEF treatment on emblica juice may offer an enormous potential for upgrading its quality than the heat processing method