GB2121668A

GB2121668A - Candied fruit and vegetable products and manufacture thereof

Info

Publication number: GB2121668A
Application number: GB08217011A
Authority: GB
Inventors: Te-Kuijun
Original assignee: JUN TE KUI
Current assignee: JUN TE KUI
Priority date: 1982-06-11
Filing date: 1982-06-11
Publication date: 1984-01-04

Abstract

A method of processing fruits and vegetables to obtain an expanded candied product in which the natural product is prepared, soaked in an aqueous sugar solution, washed, pressurised and depressurised and conditioned. The product obtained from this method has different appearance, texture, taste and chewiness as compared with the conventional candied fruits, and particularly has an increased volume.

Description

SPECIFICATION Candied fruit and vegetable products and manufacture thereof This invention relates to a method of processing candied fruits and vegetables and more particularly and specifically to an expanded candied fruit or vegetable product containing a moisture in the range of about 2 and 5% by weight of the product.

The product according to the present invention differs from the conventional candied fruits in appearance, texture as well as taste, firmness and chewiness.

Raw materials usable in the present invention include fruits such as bananas, pineapples, apples and pears as well as the other agricultural vegetable products such as sweet potatoes, potatoes and taros.

According to the invention there is provided a method for producing a candied fruit or vegetable product which comprises:- a. subjecting a fruit or vegetable material to an aqueous sugar solution for a time sufficient to dehydrate the materials; b. washing the dehydrated materials; c. draining and moderately drying the washed materials; d. subjecting the dried materials to a temperature of 85 to 95"C in a sealed container until the pressure exceeds atmospheric pressure and then rapidly reducing the pressure in the vessel to cause the materials to expand; and e. maintaining the heated expanded materials at a relative humidity of from 5 to 20% until the materials are cooled to ambient temperature.

The invention also provides a sugar impregnated fruit or vegetable product expanded by 30 to 50% in relation to the original natural volume of the product and having a moisture content of from 2 to 5% by weight of product.

The process generally includes steps of preparation, soaking, washing, draining, pressurisingdepressurising and conditioning.

Specific procedures for each of the above mentioned steps is as follows 1. Preparation (where necessary): this step can include peeling the skin of the materials if necessary, removing any defects and bruises, and slicing or cutting the material into strips or cubes as desired.

2. Soaking: soaking or immersing the prepared materials in a sugar solution preferably a saturated aqueous solution of sugar for from 8-20 hr preferably at ambient temperature to dehydrate the materials by osmotic pressure of the sugar solution. During this step the coloring matter will usually migrate to the solution from the materials and the surface of the materials thus treated will turn to light to white color. The sugar impregnates the material.

3. Washing: any excess sugar solution can be removed from the surface of the soaked material in a continuous flow of water or by spraying of water to avoid the materials sticking together.

4. Draining: after the materials are removed from the washer, the materials can be drained and allowed to dry until the moisture content falls to from 10-20% by weight of material.

5. Pressurising-Depressurising: this step which forms a significant characteristic of the present invention can be carried out in specially designed apparatus consisting of an air-tight vessel or barrel or compartment and a vacuum tank connected thereto by a pipe through a valve means, and the latter further being connected to a vacuum pump. The drained and moderately dried materials are placed in the temperature-controlled air tight barrel and are preferably held there at a temperature of from 85 to 95"C for 10 - 30 minutes. During this stage, the moisture contained in the materials evaporates and the pressure in the barrel consequently increases.As soon as the pressure rises to from 2-5Kg/cm2.G., (i.e. significantly in excess of atmospheric) the valve means is opened to connect the barrel to the vacuum tank which is maintained at a pressure of from 50-70 mm Hg. In this manner, the pressure in the barrel decreases instantaneously, thus causing the materials to expand their volume by approximately 30-50% in relation to the natural original volume of the material. The materials are held at the barrel, while operating the vacuum pump, until the moisture content thereof decreases to 2.5% by weight of material.

6. Conditioning: the purpose of this step is to avoid shrinking of the hot materials (at about 90"C) removed from the barrel and to maintain the desired expanded product. Thus before exposing in air, the hot materials are temporarily maintained in a conditioner kept at a relative humidity of about 5-20%, until the materials completely cool to ambient temperatures.

The invention will now be illustrated by the following Examples, Example 1 Processing expanded candied bananas Moderately ripened bananas were peeled and cut into cubes. These cubes were soaked in a saturated sugar solution for 10 hr at 25"C and then solution adhered to the surface of the bananas was removed by water spraying, followed by draining and drying in the air until the mositure content falls to 10% by weight. The bananas thus treated were placed into an airtight container at a controlled temperature maintained at 90"C for about 20 minutes. When the pressure in the container had risen to 2.5Kg/Cm2G, a valve means was opened to connect the container with a vacuum tank maintained at 50mmHg by a vacuum pump.After standing 10 hours, the bananas were placed, while hot, into a conditioner controlled at a relative humidity of 10% and allow to cool down to room temperature. The product thus obtained has an increased volume of about 50% as compared to the original natural and preserved the fresh aroma and flavor of banana. Moisture content was 3% by weight of product.

Example 2 Processing expanded pineapples The raw materials were prepared by peeling and slicing. The procedure of Example 1 was repeated except for the following: The sliced pineapples were pre-dried in air to reduce the moisture content to about 60% by weight and then soaking was conducted for 10 hours at 30"C. The bananas were subjected to pressurising-depressurising treatment from 4Kg/Cm2.G to instantaneously drop to 70mmHg. The product obtained has an increased volume of about 30% and preserved the fresh aroma and flavor of pineapple and the moisture content was 2.5%.

Example 3-4 Processing expanded apples and sweet potatoes Example 1 was repeated each for each of the two different raw materials, except for variations of the conditions as listed in the Table below. The results are also shown in the same Table.

Increase in volume Pressurising/ Condition- over natural Example Soaking Depressurising ing product relative Time humidity 3. Apples 8hr, 30"C From 4Kg/Cm2.G to 40mmHg 15% 5hr 30% 4. Sweet potatoes 15hr,30"C From 4Kg/Cm2.G to 60mmHg 15% 5hr 25%

Claims

1. A method for producing a candied fruit or vegetable product which comprises: a. subjecting a fruit or vegetable material to an aqueous sugar solution for a time sufficient to dehydrate the materials: b. washing the dehydrated materials; c. draining and moderately drying the washed materials; d. subjecting the dried materials to a temperature of 85 to 95"C in a sealed container until the pressure exceeds the atmospheric pressure and then rapidly reducing the pressure in the vessel to cause the materials to expand; and e. maintaining the heated expanded materials at a relative humidity of from 5 to 20% until the materials are cooled to ambient temperature.

2. A method according to claim 1 wherein the fruit or vegetable material is peeled, any defects removed and the peeled material is cut to a desired size prior to soaking in the sugar solution.

3. A method according to either of claims 1 and 2 wherein the material is immersed in a saturated aqueous sugar solution for from 8 to 20 hours at ambient temperature.

4. A method according to any one of claims 1 to 3 wherein the material is drained and moderately dried until the moisture content is from 10 to 20% by weight of material.

5. A method according to any one of the preceding claims wherein the materials are held in the sealed container at from 85 to 95"C for 10 to 30 minutes.

6. A method according to any one of the preceding claims wherein, when the pressure in the container reaches from 2 to 5Kg/Cm2.G the pressure is reduced to 50-70mmHg.

7. A method according to any of the preceding claims wherein the material is held in the sealed container at reduced pressure until the moisture content is decreased to from 2 to 5% by weight of product.

8. A method according to any of the preceding claims wherein the material is removed from the sealed container at a temperature of about 90"C and maintained in a separate conditioner at a relative humidity of from 5 to 20% until it reaches ambient temperature.

9. A method according to any one of the preceding claims wherein the material is banana, pineapple, apple or pear.

10. A method according to any one of the preceding claims 1 to 9 wherein the material is sweet potato, potato or taro.

11. A candied fruit or vegetable product when produced by a process according to any one of the preceding claims.

1 2. A sugar impregnated fruit of vegetable product expanded by 30 to 50% in relation to the original natural volume of the product and having a moisture content of from 2 to 5% by weight of product.