CN1641300A - Ultrasonic enhanced osmotic dehydrating method and apparatus - Google Patents

Abstract

The invention relates to an ultrasonic enhanced osmotic dehydration method and device. At room temperature, solid sucrose is dissolved in water to form a sucrose solution. The concentration (weight ratio) of the sucrose solution used is 40-70%. The material is ripe, smooth-skinned fresh fruit, such as apples, pears, etc. Before osmotic dehydration, cut the material into slices of different thicknesses, put them into a container filled with sucrose solution, the ratio of solid to liquid is 0.5-2:10, and carry out ultrasonic osmotic dehydration at room temperature. After dehydration, the dehydrated material is taken out and weighed, and then put into an oven to dry until it is absolutely dry, then taken out and weighed again, and finally the result is processed by a computer. The device used to implement the above method in the present invention is mainly an ultrasonic generator, and the ultrasonic waves generated by the generator output ultrasonic waves to the material liquid through the ultrasonic transducer rod.

Description

Ultrasonic enhanced osmotic dehydration method and device

technical field

The invention relates to an ultrasonic enhanced osmotic dehydration method.

The invention also relates to a device for carrying out the above-mentioned method.

Background technique

Osmotic dehydration refers to a method in which fruits and vegetables are placed in high osmotic pressure media at a certain temperature to remove part of the water by using the different concentrations on both sides of the membrane to generate osmotic pressure. Fruits and vegetables that have undergone osmotic dehydration still have the flavor that fruits and vegetables should have. , color, texture, and nutritional quality, the sensory quality of its products is almost the same as that of fresh fruits and vegetables. Osmotic dehydration can be used as a pretreatment method for fruit and vegetable processing, combined with fruit and vegetable drying, freezing, sterilization, storage and other methods. Usually, osmotic dehydration is a very slow process, so it is necessary to adopt certain methods to accelerate the mass transfer during osmotic dehydration without affecting the quality of fruits and vegetables.

Contents of the invention

Existing research shows that ultrasonic waves have a significant strengthening effect on osmotic dehydration, and the strengthening mechanism can be roughly summarized as follows: ultrasonic waves cause macroscopic turbulence of the fluid, which plays a role in stirring the solution and maintains the timely return of high-concentration solutions; The flow can weaken the boundary layer of the solid-liquid interface and reduce the external resistance of two-way diffusion; ultrasonic waves cause local pressure fluctuations, accelerate the degassing of the material tissue, and increase the surface area of the material that actually participates in mass transfer. These will accelerate the mass transfer during osmotic dehydration. The present invention utilizes this characteristic of ultrasonic waves to provide a method for strengthening osmotic dehydration with ultrasonic waves, and a device for implementing the method.

Ultrasonic enhanced osmotic dehydration method provided by the invention is:

Dissolving solid sucrose in water to form a sucrose solution at room temperature, the concentration (weight ratio) of the sucrose solution used is: 40-70%. The material is ripe, smooth-skinned fresh fruit, such as apples, pears, etc. Before osmotic dehydration, cut the material into slices of different thicknesses, put them into a container filled with sucrose solution, the ratio of solid to liquid is 0.5-2:10, and carry out ultrasonic osmotic dehydration at room temperature. After dehydration, the dehydrated material is taken out and weighed, and then put into an oven to dry until it is absolutely dry, then taken out and weighed again, and finally the result is processed by a computer. The dehydration rate, dry matter increase rate and water content of the material are calculated using formulas (1), (2) and (3) respectively:

$\mathrm{<span\; class="notranslate">\; DW</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{\mathrm{<span\; class="notranslate">\; D.</span>}{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; ID</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; DM</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="0"\; label="DM"\; filenames="A20041000136800082.png"\; state="\{\{state\}\}">DM</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; DM</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; CW</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{{\mathrm{<span\; class="notranslate">\; DM</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In the formula: DW----the dehydration rate of the material, g _water /g _{initial dry matter} ;

W ₀ ----- initial water content of the material, g;

W _t ----- the water content of the material at the time of penetration t, g;

DM ₀ ----- initial dry matter content of the material, g;

ID ----- the increase rate of dry matter of the material, g _{dry matter increase} /g _{initial dry matter} ;

DM _t ----- the dry matter content of the material at the time of penetration t, g;

CW ----- the water content of the material at time t of penetration, g _water /g _{initial dry matter} .

The device used to implement the above method in the present invention is mainly an ultrasonic generator, and the ultrasonic waves generated by the generator output ultrasonic waves to the material liquid through the ultrasonic transducer rod.

The invention can be widely used in ultrasonic osmotic dehydration of various fruits, and compared with osmotic dehydration under the same conditions, the dehydration rate of materials can be greatly improved by adopting ultrasonic strengthening.

Description of drawings

Fig. 1 is the change curve of the moisture content and dry matter increase rate of the material of the present invention with the sound intensity.

Fig. 2 is the change curve of the water content and dry matter increase rate of the material according to the present invention with the action time period.

Fig. 3 is a schematic diagram of an ultrasonic-enhanced osmotic dehydration device of the present invention.

Detailed ways

Please refer to FIG. 1 , which is a schematic diagram of the device of the present invention. Ultrasonic generator 1 of the present invention can be but not limited to 88-1 type ultrasonic generator, ultrasonic wave is input in the material liquid through ultrasonic transducer rod 2, and its output frequency is 14-20kHz, and sound intensity is 20-50W/cm ² range, the power is adjustable from 0-250W. It should be noted that the device used in the present invention is a known device per se, but there is no report on its use for ultrasonic enhanced osmotic dehydration.

The high-quality solid sucrose with a purity of 99% is dissolved in water and fully stirred to form a uniform sucrose solution. The concentration of the sucrose solution used in the present invention can be 40-70% by weight, and this example adopts 40%. Wash, peel and core the ripe, smooth-skinned apples and pears, cut them into thin slices of different thicknesses, weigh them with an electronic balance, and put them into the container 3 containing the sucrose solution. In the range of 0.5-2:10, this example is 1:10. Insert the ultrasonic transducer 2 into the container, and keep the end of the transducer 2 about 2 cm from the liquid surface. Ultrasonic osmotic dehydration was performed at room temperature. After dehydration, the dehydrated material is taken out and weighed, and then put into an oven to dry until it is absolutely dry, then taken out and weighed again, and finally the result is processed by a computer. The dehydration rate, dry matter increase rate and water content of the material are calculated using formulas (1), (2) and (3) respectively:

$\mathrm{<span\; class="notranslate">\; DW</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{{\mathrm{<span\; class="notranslate">\; DM</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; ID</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; DM</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="0"\; label="DM"\; filenames="A20041000136800082.png"\; state="\{\{state\}\}">DM</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; DM</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; CW</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{{\mathrm{<span\; class="notranslate">\; DM</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In the formula: DW----the dehydration rate of the material, g _water /g _{initial dry matter} ;

W ₀ ----- initial water content of the material, g;

W _t ----- the water content of the material at the time of penetration t, g;

DM ₀ ----- initial dry matter content of the material, g;

ID ----- the increase rate of dry matter of the material, g _{dry matter increase} /g _{initial dry matter} ;

DM _t ----- the dry matter content of the material at the time of penetration t, g;

CW ----- the water content of the material at time t of penetration, g _water /g _{initial dry matter} .

According to the above method, the results of the enhanced osmotic dehydration of the present invention are shown in Figure 1 and Figure 2 . Figure 1 shows the relationship between the moisture content of the material and the increase rate of dry matter when the sound intensity increases from 0.5A (input electric power 125W, sound intensity about 40W/cm ² ) to 0.9A (input electric power 225W, sound intensity about 72W/cm ² ). Variety. Wherein, the material thickness is 5 mm, the dehydration time is 30 min, and the solution concentration is 40%.

Figure 2 is the curve of ultrasonic enhanced osmotic dehydration for materials with a thickness of 5mm immersed in 40% sucrose solution under the action of 0.7A sound intensity. The total dehydration time is 40min, and the ultrasonic action time is 10min, but the action time is different , acting on the first 10min, the second 10min, the third 10min and the last 10min after the start of dehydration respectively. It can be seen from the figure that although the action time of ultrasonic waves is 10 minutes, the dehydration effect is significantly different due to the different action time periods. The dehydration effect in the first 10 minutes of dehydration is better than that of the latter three cases, and the earlier the action time is, the better the dehydration effect is.

Claims (5)

1, a kind of intensified by ultrasonic wave permeating and dewatering method forms sucrose solution with the solid sucrose dissolved in water, and its concentration of used sucrose solution is counted 40-70% by weight; The material of processing to be drained off is cut into sheet, puts into the container that fills sucrose solution, solid-liquid ratio is 0.5-2: 10, under room temperature, carry out ultrasonic permeating and dewatering;

After the dehydration dehydrated material taken out and weigh, put into baking oven then and dry by the fire to over dry and take out weighing again, the gained result is handled by computer;

The dehydration rate of material, dry-matter increment rate and water ratio adopt formula (1), (2) and (3) to calculate respectively:

$\mathrm{DW}=\frac{W_0-W_t}{{\mathrm{DM}}_0}---\left(1\right)$

$\mathrm{ID}=\frac{{\mathrm{DM}}_t-{\mathrm{DM}}_0}{{\mathrm{DM}}_0}---\left(2\right)$

$\mathrm{CW}=\frac{W_t}{{\mathrm{DM}}_0}---\left(3\right)$

In the formula: the dehydration rate of DW-----material, g _Water/ g _{Initial dry-matter}

W ₀The initial water content of-----material, g;

W _t-----infiltration t is the water content of material constantly, g;

DM ₀The content of the initial dry-matter of-----material, g;

The increment rate of ID-----material dry-matter, g _{The dry-matter increasing amount}/ g _{Initial dry-matter}

DM _t-----infiltration t is the content of material dry-matter constantly, g;

CW-----infiltration t is the water ratio of material constantly, g _Water/ g _{Initial dry-matter}

2, the method for claim 1 is characterized in that, described sucrose purity is 99%.

3, the method for claim 1 is characterized in that, described material is ripe, smooth-skined fresh fruit.

4, a kind of device of implementing the described method of claim 1 is a ultrasonic generator, and to the feed liquid output ultrasonic wave, its output frequency is 14-20kHz to the ultrasonic wave that this producer produces through the ultrasonic transduction rod, and the sound intensity is at 20-50W/cm ²In the scope, power is that 0-250W is adjustable.

5, device as claimed in claim 4 is characterized in that, the end-to-end distance of described transducing rod is from the about 1-3cm of liquid level.

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