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Open-Air Sun Drying of Kokum (Garcinia indica) Rind and Its Quality Evaluation

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Abstract

Open sun drying (OSD) is most common method of kokum drying in Western Ghats of India. Crop temperature, around the crop, solar temperature and rate of moisture evaporation are the important parameters of OSD of kokum. In this paper, an attempt has been made to study the OS drying characteristics of kokum rind, i.e., moisture content versus time, drying rate versus moisture content and moisture ratio versus drying time. The convective heat transfer coefficient operating in open sun drying conditions (natural convection) of kokum rind has also been determined based on the values of constants, C and n, which were obtained by linear regression analysis from experimental data for kokum rind. The quality parameters of kokum rind, i.e., acidity, pH, reducing sugar, non-reducing sugar, protein, carbohydrates, ash, anthocyanins, color (L, a and b value) and calorific value before OSD and after OSD of kokum rind have also be determined.

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Abbreviations

A t :

Area of tray (m2)

C :

Constant

C v :

Specific heat of humid air (J/kg °C)

g :

Acceleration due to gravity (m/s2)

G r :

Grash of number βgX3 ρ 2 v ΔT/µ 2

h c :

Convective heat transfer coefficient of crop (W/m2 °C)

I(t):

Solar intensity (W/m2)

K v :

Thermal conductivity of humid air (J/m2 °C)

m ev :

Moisture evaporated (kg)

M :

Moisture content

M 0 :

Initial moisture content (%db)

M e :

Equilibrium moisture content (%db)

n :

Constant

N u :

Nusselt number hc X/Kv

P r :

Prandtl number µ v Cv/Kv

P(T):

Partial vapor pressure at temperature T (N/m2)

Q e :

Rate of heat utilized to evaporate moisture (J/m2s)

r :

Coefficient of correlation

t :

Time (s)

T c :

Crop temperature (0C)

T e :

Temperature above crop surface (°C)

T sae :

Equivalent solar temperature on crop surface (°C)

T i :

Average of crop and humid air temperature (°C)

ΔT :

Effective temperature difference (°C)

v :

Wind velocity (m/s)

X :

Characteristic dimension (m)

β :

Coefficient of volumetric expansion (1/°C)

γ :

Relative humidity (dec.)

σ :

Stefan–Boltzmann constant 5.6696 × 10−8 (W/m2 K4)

λ :

Latent heat of vaporization (J/kg)

µ v :

Dynamic viscosity of humid air (kg/m)

ρ v :

Density of humid air (kg/m3)

ε :

Emissivity

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Authors and Affiliations

  1. Department of Agricultural Process Engineering, College of Agricultural Engineering and Technology, Dapoli, 415 712, Maharashtra State, India

    Amarja Ramesh Hande, Shrikant Baslingappa Swami & Nayansingh J. Thakor

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  1. Amarja Ramesh Hande
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  2. Shrikant Baslingappa Swami
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  3. Nayansingh J. Thakor
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Correspondence to Shrikant Baslingappa Swami.

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Hande, A.R., Swami, S.B. & Thakor, N.J. Open-Air Sun Drying of Kokum (Garcinia indica) Rind and Its Quality Evaluation. Agric Res 5, 373–383 (2016). https://doi.org/10.1007/s40003-016-0229-3

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