Stability of vitamin C in broccoli based on the chemical reaction kinetics, micro-region state diagram, and empirical correlations. Issue 1 (1st January 2021)

• Record Type: Journal Article
• Authors: Rahman, Mohammad Shafiur; Suresh, Sithara; Al-Habsi, Nasser; Al-Khusaibi, Mohamed; Al-Attabi, Zahir; Al-Subhi, Lyutha
• Is Part Of: International journal of food properties. Volume 24:Issue 1(2021)
• Page Start: 1559
• Page End: 1573
• Publication Date: 2021-01-01
• Subjects: Glass transition -- Freezing -- Freeze-drying -- Water activity -- Maximal-freeze-concentration -- Activation energy -- Hurdle technology; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664.0705
• DOI: 10.1080/10942912.2021.1977658
• Languages: English
• ISSNs: 1094-2912

Abstract

ABSTRACT: Vitamin C degradation of broccoli at different moisture and temperature was measured as a function of storage time and modeled by first-order reaction kinetics. The variation of rate constant was analyzed based on the activation energy, glass transition, BET-monolayer, micro-region state diagram, and empirical correlations. Three domains of chemical reactions were observed as a function of temperature. In the case of broccoli with freezable water (i.e. moist), the first critical temperature (i.e. Tc ) was observed at −20°C ( Tc / Tg ′′′: 0.829), which was close to the Tg ′′′ (i.e. experimental ultimate maximal-freeze-concentration glass transition) (−32.2°C); while second critical temperature (i.e. Ts ) was observed at 60.0°C (i.e. Ts / Tg ′′′: 1.383). The activation energy values were 13.6, 75.0, and 43.6 kJ/mole for the phase 1 (moist-glassy), phase 2 (moist-glassy-rubbery) and phase 3 (moist-rubbery-flow), respectively. In the case of frozen-broccoli with un-freezable water, the first critical temperature (i.e. Tc ) was observed at 5°C ( Tc / Tgi : 1.021), which was close to the Tgi (onset glass transition) (−0.8°C); while the second critical temperature (i.e. Ts ) was observed at 70.0°C (i.e. Ts / Tgi : 1.260). The second critical temperature was close to the mechanical glass transition temperature. The activation energy values were 13.1, 69.6, and 72.4 kJ/mole for phase 1, phase 2 and phase 3, respectively. Each experimental rate constant was located in the micro-regions of the state diagram. Principal component analysis showed that reaction rates can be grouped into different micro-regions, except one data point in the micro-region 12. This could be due to the wider domain of this region and further sub-micro-regions could be defined. Finally, empirical correlations were developed as dimensionless moisture, temperature, and rate constant, and explored the possibility of developing a generic universal equation.