HIGH TEMPERATURE DRYING CHARACTERISTICS AND MOISTURE ADSORPTION ISOTHERMS OF BLACK PLUM (VITEX DONIANA) SYRUP AND SYRUP-STARCH

Figures & data

Figure 1. Rate of dehydration of 1 mm thick Black plum syrup-starch mixtures 60°C.

Figure 2. Rate of dehydration of 1 mm thick Black plum syrup-starch mixtures at 90°C.

Figure 3. Drying curve of Black plum syrup-starch mixtures at 60°C.

Figure 4. Drying curves of Black plum syrup-starch mixtures at 90°C.

Table 1. Percentage Moisture Lost During 2 hr Drying of Black Plum Syrup-Starch Mixtures at Different Temperatures

	% Moisture
Temp (°C)	40% Starch	30% Starch	20% Starch
90	73.39^a	78.40^b	83.17^c
80	68.53^a	71.31^b	80.83^c
70	67.97^a	70.90^b	79.87^c
60	54.97^a	65.42^b	74.16^c
S.E.	4.55	3.07	2.21
L.S.D. (0.05)	2.09	1.72	1.46

Values within a row with different superscripts are significantly (p < 0.05) different.

Figure 5. Effect of composition on moisture sorption isotherms of Black plum syrup-starch mixtures pre-dried at 60°C.

Table 2. Parameter Values of the BET and Henderson Models to Describe the Isotherm of Starch-Black Plum Syrup Mixture Previously Dried at 60 °C

Isotherm	BET1 ^x				Henderson2 ^y
	C	%Mo	aw	%E	break	% dry basis	aw	K2	n2	k1	n1	%E
Syrup (S)	9.02^c	14.38^bc	0.24^a	4.5	1.50	31.62^c	0.66^a	5.01 × 10^−5	0.614	5.01 × 10^−5	0.614	2.1
S + 20% Starch	1.05^a	23.42^d	0.58^b	7.3	Not Determined
S + 30% Starch	3.17^b	15.65^c	0.36^ab	6.9	1.40	25.12^b	0.60^a	1.26×10^−2	0.702	1.26 × 10^−2	0.702	6.6
S + 40% Starch	4.30^b	13.06^b	0.30^a	3.8	Not Determined
100% Starch	10.30^d	11.58^a	0.21^a	7.8	1.25	17.78^a	0.41^a	∞	∞	1.58 × 10^−3	1.567	6.1

^xUp to a_w 0.45.

^yUp to a_w 0.97.

C = constant related to heat of absorption.

%M_o = % monolayer moisture content on dry weight basis.

%E = % mean relative deviation.

break = log value on x-axis at the junction of two straight curves.

% dry basis = Equivalent moisture content of the ‘break’ value.

n and k = constants depending on the material.

Values with different alphabets within a column differ significantly (p < 0.05) using the LSD technique.