In this research, a state diagram of coriander leaves was developed by measuring glass line, freezing curve, and solid melting line as a function of solid content. In addition, maximal-freeze-concentration condition was determined. Rahman-Gordon-Taylor equation was used to model the glass transition line and critical parameters were 172 °C (i.e., glass transition at dry solids) and 1.74 (i.e., solid-water plasticization), respectively. Solid melting line was modeled by Flory–Huggins equation, and solid-water interaction parameter at melting was estimated as 0.536. The freezing point decreased with the increase of solids and Chen equation derived from Clausius–Clapeyron equation was used to model freezing curve. Chen’s model parameters, i.e., molecular weight ratio of water and solids and unfreezable water, were estimated as 0.134 and 0.188 g/g dry solids, respectively. The ultimate freeze-concentration conditions, <InlineEquation ID="IEq1"> <EquationSource Format="TEX">${({T}_{\text{m}}\prime )}_{\text{u}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mo stretchy="false">(</mo> <msub> <mi>T</mi> <mtext>m</mtext> </msub> <mo>′</mo> <mo stretchy="false">)</mo> </mrow> <mtext>u</mtext> </msub> </math></EquationSource> </InlineEquation> and<InlineEquation ID="IEq2"> <EquationSource Format="TEX">${({T}_{\text{g}}\prime \prime \prime )}_{\text{u}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mo stretchy="false">(</mo> <msub> <mi>T</mi> <mtext>g</mtext> </msub> <mo>″</mo> <mo>′</mo> <mo stretchy="false">)</mo> </mrow> <mtext>u</mtext> </msub> </math></EquationSource> </InlineEquation>, were − 25.5 °C and − 30.5 °C, respectively. The conceptual maximal-freeze-concentration conditions, Tgiv and Xs′ from the state diagram were determined as 110.0 °C and 0.68 g/g solids. Finally, micro-regions 1 and 2; 4; 8 and 9; and 11, 12, and 13 were identified in the state diagram. In future studies, physicochemical changes in coriander leaves need to be investigated in different micro-regions. Graphical Abstract

State Diagram of Freeze-Dried Coriander Leaves: Measuring and Modeling of Freezing Point, Glass Transition, Solid Melting, and Maximal-Freeze-Concentration Conditions

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发表日期：

2025年12月4日

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Saleh Muhammed Raqib,
Nasser Al-Habsi,
Mohammad Shafiur Rahman

摘要

In this research, a state diagram of coriander leaves was developed by measuring glass line, freezing curve, and solid melting line as a function of solid content. In addition, maximal-freeze-concentration condition was determined. Rahman-Gordon-Taylor equation was used to model the glass transition line and critical parameters were 172 °C (i.e., glass transition at dry solids) and 1.74 (i.e., solid-water plasticization), respectively. Solid melting line was modeled by Flory–Huggins equation, and solid-water interaction parameter at melting was estimated as 0.536. The freezing point decreased with the increase of solids and Chen equation derived from Clausius–Clapeyron equation was used to model freezing curve. Chen’s model parameters, i.e., molecular weight ratio of water and solids and unfreezable water, were estimated as 0.134 and 0.188 g/g dry solids, respectively. The ultimate freeze-concentration conditions, ${({T}_{\text{m}}\prime )}_{\text{u}}$ ${(T_{m}')}_{u}$ and ${({T}_{\text{g}}\prime \prime \prime )}_{\text{u}}$ ${(T_{g} ″')}_{u}$ , were − 25.5 °C and − 30.5 °C, respectively. The conceptual maximal-freeze-concentration conditions, T_g^iv and X_s′ from the state diagram were determined as 110.0 °C and 0.68 g/g solids. Finally, micro-regions 1 and 2; 4; 8 and 9; and 11, 12, and 13 were identified in the state diagram. In future studies, physicochemical changes in coriander leaves need to be investigated in different micro-regions.

Graphical Abstract