Colour degradation and rheology of green chilli puree during thermal processing

Abstract

The kinetics of degradation of both green‐ and total‐colour of green chilli puree was studied at selected temperatures (50–90 °C). A fractional conversion concept was applied to determine the kinetic parameters. The degradation of green‐ and total‐colour followed first order reaction kinetics. In the case of green colour the data was based on changes in Hunter –a value while L × a × b was found to adequately represent total colour change. Dependence of the rate constant during heat treatment obeyed the Arrhenius relationship. The activation energy values for green‐ and total‐colour degradation were 23.04 and 25.02 kJ mol–1, respectively. These results indicated that total colour should be used as the quality indicator during thermal processing of green chilli puree. The pungency of green chilli puree decreased during thermal processing as the capsaicin content was reduced from 559 to 441 μg g–1 while the Scoville heat unit decreased from 8500 to 7480. The puree behaved as a shear‐thinning fluid and the flow activation energy at 100 r.p.m. equalled 19.22 kJ mol–1.

Peroxidase inactivation and colour changes during ohmic blanching of pea puree

“…Total colour includes the changes by non-enzymatic browning in addition to the degradation of green colour. Total colour may therefore be used as the quality indicator instead of green colour during thermal processing of green purees as mentioned in Ahmed, Shivhare and Debnath (2002). Garza et al (1999) applied first order reaction kinetics for non-enzymatic colour changes of peach puree during thermal treatment and found the reaction rate constant of 71 ± 4 · 10 À3 min À1 for ''L/L 0 '' colour parameter at 98°C water bath.…”

“…Colour can be used as a quality indicator to evaluate the extent of deterioration due to thermal processing (Avila & Silva, 1999). Although several kinetic studies have been made to evaluate the colour changes of food purees during hot water blanching (Ahmed, Shivhare, & Debnath, 2002;Ahmed, Shivhare, & Ramaswamy, 2002;Ahmed, Shivhare, & Singh, 2004;Avila & Silva, 1999;Barreiro, Milano, & Sandoval, 1997;Garza et al, 1999;Zanoni, Pagliarini, Giovanelli, & Lavelli, 2003), no published data has been found in the literature discussing the effects of ohmic blanching on colour kinetics of pea puree.…”

Effect of cooking on the capsaicinoids and phenolics contents of Mexican peppers

“…In general, boiling induced smaller colour changes in yellow and red peppers than in green ones. Similarly, Ismail and Revathi (2006) reported only small colour changes (L*, a*, and b*) in puree of red peppers treated in a wide range of temperatures while Ahmed, Shivhare, and Debnath (2002) reported high colour changes in puree of green peppers during heat processing. This suggest that yellow (zeaxanthin, violaxanthin, anteraxanthin, bcryptoxanthin, b-carotene, and curcubixanthin A) and red (capsanthin, capsanthin 5,6-epoxide, and capsorubin) carotenoids are more thermoresistant than chlorophylls in peppers.…”

Modelagem matemática e parâmetros qualitativos da secagem de folhas de capim-limão [Cymbopogon citratus (DC.) Stapf]

“…Tais resultados estão de acordo com estudos realizados em tratamentos térmicos com pimenta verde (Ahmed et al, 2002) e pera (Ibarz, 1999). TABELA 5.…”