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 effect of increased freezing speed, reduced juice loss, and more consistent size

Active Publication Date: 2014-11-12
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 method consumes a lot of energy, and the temperature of frozen products is not uniform
[0011] 3) The single-frequency ultrasonic-assisted freezing method is limited by a single frequency and cannot maximize the cavitation effect of ultrasonic waves

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
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Effect test

Embodiment 1

[0030] figure 1 It 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. A circulating refrigerant inlet 1 is provided above the ultrasonic treatment tank 2 , there is a circulating refrigerant outlet 6 below, and a wire frame for holding the sample is arranged 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 Devices 7 are evenly distributed on 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-converting ultrasonic intensification in this embodiment includes the follow...

Embodiment 2

[0033]The ultrasonic processing device used in this embodiment is the same as that in Embodiment 1. The method for improving the freezing speed and quality of lychees by frequency-converting ultrasonic intensification includes the following steps: buy fresh lychees that have been picked for no more than 24 hours, wash them, and sort and remove them that have become corrupted. Frozen ingredients. Weigh 360g and pre-cool to 4°C. Take the pre-cooled concubine and insert a 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 ratio of solid to liquid is 1:40 , and began to record the core temperature of the concubine. When it drops to near the freezing point, change the ultrasonic frequency to assist in freezing the lychees to -20°C. After the freezing is over, take out the lychees. The frequency conversion ultrasonic processing conditions are: the po...

Embodiment 3

[0035] The ultrasonic processing device used in this embodiment is the same as that in Embodiment 1. The method for improving the freezing speed and quality of litchi by frequency-converting ultrasonic enhancement includes the following steps: purchase fresh hanging green litchi that has been picked for no more than 24 hours, wash, and pick and remove unsuitable corrupted litchi. Frozen ingredients. Weigh 360g and pre-cool to 4°C. Take the pre-cooled hanging green and insert a 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 ratio of solid to liquid is 1:40. , start to record the core temperature of the hanging green. When it drops to near the freezing point, change the ultrasonic frequency to assist in freezing the litchi to -18°C. After the freezing is over, take out the hanging green. The frequency conversion ultrasonic processing conditio...

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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 food, in particular to a method for enhancing the freezing speed and quality of litchi by frequency-converted 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 lowering the temperature and changing the form of water in the food, so as to prevent food spoilage and maintain 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 fresh-keeping time. [0003] Generally speaking, during the freezing process, due to the relatively slow heat transfer rate during slow freezing, water concentrates in the extracellular crystallization, and due to the difference in concentration between the inner and outer cells, the cells shrink and become excessively dehydrated. Moreover,...

Claims

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Application Information

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Patent Type & Authority Patents(China)
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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