Thermal Degradation Kinetics of Chlorophyll in Pureed Coriander Leaves

Abstract

Coriander leaves are widely used in cooking throughout the world. Thermal degradation kinetics of chlorophyll a, b, and total chlorophyll in coriander leaf puree was investigated at varying levels of pH (4.5-8.5) and processing temperature (80-145°C). Coriander puree at pH 4.5 was processed at 80°to 100°C, whereas that at pH 5.5 to 8.5 was processed at 105°to 145°C. Chlorophyll degradation followed first-order reaction kinetics. Good agreement was found between estimated and experimental chlorophyll retention in all cases (R 2 >0.80). Activation energies ranged from 6.57 to 96.00 kJ/mol. Reaction rate and activation energy data indicated that chlorophylls were more stable at alkaline pH. Transition state theory was applied to estimate the enthalpy, entropy, and Gibbs free energy of activation. Enthalpy of activation (ΔH # ) ranged from 3.46 to 91.99 kJ/mol, whereas entropy of activation (ΔS # ) ranged from −0.265 to −0.047 kJ/(mol K). The overall free energy change was 107.55 kJ/mol. Results indicated that, the compensation effect did not exist for chlorophyll degradation in coriander puree during thermal processing.

Enthalpy entropy compensation during thermal degradation of chlorophyll in mint and coriander puree

“…The coefficients k i , R 2 , and standard error (S.E.) for chlorophyll degradation in coriander and mint puree were estimated (Rudra et al, 2007) and are provided in Tables 2 and 3. The excellent agreement between experimental and calculated values demonstrated the applicability of the first-order rate kinetic equation to describe the degradation of chlorophylls of coriander and mint puree during thermal processing.…”

“…The leaves were de-stemmed, washed and drained. Coriander and mint puree were prepared by blanching and stone-grinding followed by passing through a sieve of 1.19 mm aperture size (Rudra et al, 2007;Rudra et al, in press). The inherent pH of the coriander and mint puree were 6.3 ± 0.15 and 5.65 ± 0.25 respectively.…”

Stability of chlorophyll–protein complex (photosystem II) in processed spinach: Effect of high hydrostatic pressure

“…Extraction of chlorophylls from PS II solution was done according to the method described by Rudra et al [13] Briefly, 200 μL PS II solution was mixed with 3.8 mL 80% (v/v) cold acetone solution, centrifuged at 3000g for 10 min at 4°C. The supernatant was collected and filtered through a Millipore filter (0.22 µm) before HPLC analysis.…”

ALTERATIONS IN OXIDANTS AND PHOTOSYNTHETIC PIGMENTS AS POSSIBLE DETERMINANTS OF CROSS-LOCATIONAL ADAPTABILITY POTENTIAL IN TWO LEMONGRASS (Cymbopogon citratus) POPULATIONS

“…The altered climatic conditions produce an imbalance in cellular energy, thus changing the redox state of the thylakoid lamellae. Of the Chl-a and Chl-b, a higher maintenance of Chl-a has been paid due attention while loss of Chl-b is considered as a great stress (Wahid, 2007;Rudra et al, 2008). Conversely, Koca et al (2007) reported that Chl-a is more susceptible under heat stress and can be degraded approximately 2 to 10 times faster than Chl-b.…”