Method for improving the freezing speed and quality of litchi chinensis through variable-frequency ultrasonic enhancement

A frequency conversion ultrasonic, freezing speed technology, applied in the preservation of fruits/vegetables by freezing/refrigeration, food preservation, preservation of fruits/vegetables by radiation/electrical treatment, etc., can solve the problem of slow freezing speed, damage to cell membrane and structure, and high energy consumption and other problems, to achieve the effects of reduced juice loss, increased freezing speed, and more consistent size

Active Publication Date: 2013-06-26
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] 1) The freezing speed of the traditional method is too slow, and the size of the formed ice crystals is large and uneven, which causes a certain degree of damage to the cell membrane and structure
[0010] 2) The traditional freezing meth

Method used

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  • Method for improving the freezing speed and quality of litchi chinensis through variable-frequency ultrasonic enhancement

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] figure 1 This is a schematic diagram of the ultrasonic treatment device used in this embodiment. As shown in the figure, it includes an ultrasonic treatment tank 2, a T-type thermocouple 3, a multi-channel data recorder 4, a plurality of ultrasonic transducers 7, and an ultrasonic control panel 8. The upper part of the ultrasonic treatment tank 2 is provided with a circulating refrigerant inlet 1 , there is a circulating refrigerant outlet 6 below, and a wire frame for holding the sample is provided inside; the T-type thermocouple 3 is in contact with the sample 5 when in use, and is used to measure the freezing temperature change of the sample 5; multiple ultrasonic transducers The devices 7 are evenly distributed at the bottom of the ultrasonic treatment tank 2 and are respectively connected with the ultrasonic control panel.

[0031] The method for improving the freezing speed and quality of lychees by frequency conversion ultrasonic enhancement of the present embod...

Embodiment 2

[0033]The ultrasonic treatment device adopted in the present embodiment is the same as that of Embodiment 1, and the method for enhancing the freezing speed and quality of lychees by frequency conversion ultrasonic wave enhancement comprises the following steps: purchasing fresh lychees that have been picked for no more than 24h, wash them, and pick and remove the lychees that have been corrupted. Frozen raw materials. Weigh 360g and pre-cool to 4°C. Take the pre-cooled Feizixiao and insert the T-type thermocouple into the ultrasonic treatment tank. The temperature in the ultrasonic treatment tank is below -18℃, the refrigerant is 50% ethanol aqueous solution (v / v), and the material-liquid ratio is 1:40 , and began to record the temperature of the concubine's smile. When it drops to near the freezing point, change the ultrasonic frequency to assist in freezing the lychees to -20°C. When the freezing is over, take out the concubine smile. The frequency conversion ultrasonic t...

Embodiment 3

[0035] The ultrasonic treatment device adopted in the present embodiment is the same as that in Embodiment 1, and the method for enhancing the freezing speed and quality of lychees by frequency conversion ultrasonic waves includes the following steps: purchasing fresh green lychees that have been picked for no more than 24 hours, wash them, and pick and remove lychees that are not suitable for corruption. Frozen raw materials. Weigh 360g and pre-cool to 4°C. Take the pre-cooled hanging green and insert the T-type thermocouple into the ultrasonic treatment tank. The temperature in the ultrasonic treatment tank is below -18 °C, the refrigerant is 50% ethanol aqueous solution (v / v), and the material-to-liquid ratio is 1:40 , and start recording the green core temperature. When it drops to near the freezing point, change the ultrasonic frequency to assist in freezing the lychees to -18°C. When the freezing is over, take out and hang green. The frequency conversion ultrasonic pro...

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Abstract

The invention discloses a method of improving the freezing speed and quality of litchi chinensis through variable frequency ultrasonic enhancement. The method comprises the following steps: pretreating fresh litchi chinensis, precooling, adding refrigerating fluid for impregnating, and conducting variable-frequency ultrasonic treatment, namely treating for 20-60s under the frequency of 20-40kHz by adopting the ultrasonic wave with the power of 40-300W, and then increasing the frequency to 40-80kHz for treating for 20-60s under the equal power. With the method, the freezing speed of the litchi chinensis can be increased, the freezing time can be shortened, and unfrozen juice loss rate can be reduced.

Description

technical field [0001] The invention relates to the technical field of frozen foods, in particular to a method for enhancing the freezing speed and quality of lychees by means of frequency conversion ultrasonic waves. Background technique [0002] Food freezing technology is to inhibit the activity of microorganisms and enzymes and reduce the activity in the food matrix by reducing the temperature and changing the form of water in the food, thereby preventing food spoilage and maintaining the freshness and nutritional value of food. Food freezing technology is currently the most commonly used food storage method with better effect, lower price and longer preservation time. [0003] Generally speaking, in the freezing process, slow freezing is due to the relatively slow heat transfer rate, and the water is concentrated outside the cells to crystallize. Due to the difference in concentration inside and outside the cells, the cells shrink and become excessively dehydrated. Mor...

Claims

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Application Information

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IPC IPC(8): A23B7/00A23B7/015A23B7/05
Inventor 孙大文胡芬曾新安张志航高文宏
Owner SOUTH CHINA UNIV OF TECH
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