Stability of vitamin C in broccoli based on the chemical reaction kinetics, micro-region state diagram, and empirical correlations

Mohammad Shafiur Rahman*, Sithara Suresh, Nasser Al-Habsi, Mohamed Al-Khusaibi, Zahir Al-Attabi, Lyutha Al-Subhi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

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.

Original languageEnglish
Pages (from-to)1559-1573
Number of pages15
JournalInternational Journal of Food Properties
Volume24
Issue number1
DOIs
Publication statusPublished - 2021
Externally publishedYes

Keywords

  • Activation energy
  • Freeze-drying
  • Freezing
  • Glass transition
  • Hurdle technology
  • Maximal-freeze-concentration
  • Water activity

ASJC Scopus subject areas

  • Food Science

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