CN102326653B - Preserved fruit drying method - Google Patents

Abstract

The invention discloses a preserved fruit drying method. At present, heating drying is frequently applied in large scale production of preserved fruit drying, the drying time is 24-72 hours, the drying temperature is 70-85 DEG C, the quantity of steam consumed in the production process is high, the time is long, the temperature is high, the energy consumption is high, and the defects cause reducing sugar in the preserved fruit to be increased to more than 10%, thus a product is easily subjected to colour change and sugar flowing reaction, and the subsequent retention period and shelf life can be shortened. In the invention, hot air and cold dehumidification are combined, and three steps, namely hot air drying, intermittent moisture uniform distribution and dehumidification, are used for drying the preserved fruit. The preserved fruit drying method disclosed by the invention has the characteristics of shorter drying time and low drying temperature, the content of the reducing sugar is improved by less than 2%, and the product has stable quality in colour, lustre and sugar flowing aspects; and most importantly, the preserved fruit drying method is carried out at low temperature, thus the flavour of the preserved fruit is conserved to the utmost extent, and the market acceptable high quality requirement can be achieved.

Description

A kind of preserved fruit drying means

Technical field

What the present invention relates to is a kind of drying means of preserved fruit, belongs to the deep process technology field of fruit food.

Background technology

Drying is a critical process during preserved fruit is produced, these quality index of the local flavor of preserved fruit, color and luster, outward appearance, content of reducing sugar, storage life and shelf life, and all relevant with drying means, a kind of preserved fruit drying means of science can be produced high-quality preserved fruit.Contained moisture has Free water, physical-chemical bond water, chemical bonding water three classes in the fruit.Free water refers to the impact that is not subjected to material molecule bonding force or structural capacity, and freely the water of activity can be utilized by microorganism.Physical-chemical bond water refers to and fettered by molecule bonding force or structural capacity, and freely the water of activity partly can be utilized by microorganism.Chemical bonding water refer to molecule part, can not be freely movable water, do not utilized by microorganism.Preserved fruit is dry to be evaporated the Free water in the fruit and part physical-chemical bond water exactly, and the moisture of preserved fruit is reduced, and reaches the purpose of preserving food, also realizes the expection local flavor in the food manufacturing simultaneously.

As everyone knows, the sugar that has a reducing power is called reduced sugar.The representative that the unimolecule glucose that produces in the preserved fruit production process, fructose are exactly reduced sugar, minute clamp mechanism of reduced sugar has the hemiacetal hydroxyl, can reduce Fehling (H.von Fehling) reagent or Tuo Lunsi (B.Tollens) reagent, these sugar can with preserved fruit in amino acid generation Maillard reaction and produce Melanoidins or melanin, be that product colour deepens even blackening, reduce the main cause of the outward appearance visual effect of preserved fruit.No matter be the sucrose that contains in the fruit, the perhaps sucrose that adds of manufacturing process, under the effect of acid and moisture, temperature is higher, and sucrose more easily is broken down into reduced sugar, also just more easily destroys the quality of preserved fruit, the quality of reduction preserved fruit.

In order to produce high-quality preserved fruit, the preserved fruit drying means is all targeted in the technological progress of preserved fruit production, by the improvement of preserved fruit drying means, improves the product quality of preserved fruit.Through retrieval, find that application number is 201010282097.1, denomination of invention is: a kind of application for a patent for invention of mango freeze-drying method, in producing, mango fruit fourth adopted cryodesiccated method, obtained the higher mango fruit fourth of quality.And application number is 201010561364.9, denomination of invention is: a kind of application for a patent for invention of microwave vacuum drying method for banana slices, it is expanded that the method that the applied microwave vacuum drying technique combines with vacuum is carried out drying to banana chip, improves the quality of drying expanded banana chip.Freeze drying and microwave drying, all be the new method in the dry technology, perhaps have higher quality with the preserved fruit of these method dryings, but these methods also there is its limitation simultaneously, adopt freeze-drying method such as preserved fruit, have the shortcoming that investment is large, production capacity is little, energy consumption is large.And microwave vacuum drying method be used for the preserved fruit drying still insurmountable problem be that the preserved fruit hot-spot of drying oven causes variable color even burns; Because will make vacuum condition, equipment capacity is little simultaneously.So above-mentioned two kinds of methods all are difficult to use in the industrialization of preserved fruit.At present; what application was more in large-scale production is heat drying, and the thermal source of use generally is the steam that boiler provides, and drying time is between 24-72 hour; baking temperature 70-85 ℃; consume in process of production quantity of steam large, the time is long, and temperature is high; power consumption is exactly greatly the deficiency of heating and drying method; these deficiencies also cause the reduced sugar in the preserved fruit to be increased to more than 10%, make product variable color, the reaction of stream sugar easily occur, shorten follow-up storage life and shelf life.Therefore, seeking a kind of drying means scientific and reasonable in large-scale production, is meaning of the present invention.

Summary of the invention

Purpose of the present invention just provides a kind of drying means of preserved fruit, overcomes that the existing existing local flavor of preserved fruit drying means is bad, color and luster is not good, content of reducing sugar is high, storage life and shelf life be short, and the high-leveled and difficult deficiency with scale of input production of cost.

The purpose of foregoing invention is achieved through the following technical solutions, and a kind of drying means of preserved fruit comprises the steps:

(1) pre-treatment: with clean well-regulated bulk or the sheet of being cut to of fruit, pickled to the quality index requirement with auxiliary material, individual layer places on the netted tray, places hothouse;

(2) drying: the hothouse operating temperature is controlled at 55-65 ℃, and above-mentioned fruit is carried out drying, 5-7 hour drying time;

(3) leave standstill: the fruit after above-mentioned dry the processing was left standstill 5-7 hour in 28-38 ℃ of environment, allow moisture evenly distributes in the fruit, to exosmosis;

(4) dehumidifier: above-mentioned fruit is placed except moist chamber, and except 28-38 ℃ of moist chamber operating temperature, equipment humidity control 8-10% dehumidified time 5-7 hour, obtained the preserved fruit of water content 15-18%.

Take the present invention of above-mentioned measure, use hot blast and cold dehumidifying to combine, with heated-air drying, intermittently moisture evenly distributes and three steps that dehumidify are carried out drying to preserved fruit.The preserved fruit heated-air drying is to utilize hot blast that preserved fruit is heated, and makes the Free water in the preserved fruit, then is that physical-chemical bond water becomes water vapour and enters in the hot-air, reaches dry purpose.And cold dehumidifying is under 28-38 ℃ air conditions, the condensing agent of use dehumidifier and heat exchanger are condensed into water with airborne steam and drain, recycle the rear dry air of dehumidifying, Free water and physical-chemical bond water in the preserved fruit constantly are evaporated in the dry air, reach dry purpose.Take the present invention of abovementioned technology, gained preserved fruit moisture 15-18%, technical characterstic of the present invention is: shorten drying time, is beneficial to raising output.Baking temperature is low, hot blast uses 55～65 ℃, cold dehumidifying is used 28～38 ℃, whole process temperature is lower than 65 ℃, content of reducing sugar improves and to be no more than 2%, product color and luster, stream sugared aspect stay in grade, the more important thing is because low temperature, so the local flavor of preserved fruit can maximumly be preserved, and reaches the high-quality requirement of market approval.

The specific embodiment

Embodiment 1

(1) pre-treatment: will be with the mango sheet of sugar cure to index request, individual layer places on the netted tray, places hothouse;

(2) drying: the hothouse operating temperature is controlled at 55 ℃, and above-mentioned mango sheet is carried out drying, 5 hours drying times;

(3) leave standstill: the mango sheet after above-mentioned dry the processing was left standstill 5 hours in 28 ℃ of environment, allow moisture evenly distributes in the mango, to exosmosis;

(4) dehumidifier: above-mentioned fruit is placed except moist chamber, and except 28 ℃ of moist chamber operating temperatures, equipment humidity control 8-10%, obtains the Preserved Mango of water content 18% at 5 hours dehumidifying time.

Embodiment 2

(1) pre-treatment: will arrive with sugar cure the pineapple slice of index request, individual layer places on the netted tray, places hothouse;

(2) drying: the hothouse operating temperature is controlled at 65 ℃, and above-mentioned pineapple slice is carried out drying, 7 hours drying times;

(3) leave standstill: the pineapple slice after above-mentioned dry the processing was left standstill 7 hours in 38 ℃ of environment, allow moisture evenly distributes in the pineapple, to exosmosis;

(4) dehumidifier: above-mentioned fruit is placed except moist chamber, and except 38 ℃ of moist chamber operating temperatures, equipment humidity control 8-10%, obtains the pineapple preserved fruit of water content 15% at 7 hours dehumidifying time.

Embodiment 3

(1) pre-treatment: will arrive with sugar cure the cherry tomato of index request, individual layer places on the netted tray, places hothouse;

(2) drying: the hothouse operating temperature is controlled at 60 ℃, and above-mentioned cherry tomato is carried out drying, 6 hours drying times;

(3) leave standstill: the fruit after above-mentioned dry the processing was left standstill 6 hours in 30 ℃ of environment, allow moisture evenly distributes in the cherry tomato, to exosmosis;

(4) dehumidifier: above-mentioned cherry tomato is placed except moist chamber, and except 30 ℃ of moist chamber operating temperatures, equipment humidity control 8-10%, obtains the cherry tomato preserved fruit of water content 15% at 6 hours dehumidifying time.

Claims (1)

1. the drying means of a preserved fruit comprises the steps:

(1) pre-treatment: with clean well-regulated bulk or the sheet of being cut to of fruit, to the quality index requirement, individual layer places on the netted tray, places hothouse with sugar cure;

(2) drying: the hothouse operating temperature is controlled at 55-65 ℃, and above-mentioned fruit is carried out drying, 5-7 hour drying time;

(3) leave standstill: the fruit after above-mentioned dry the processing was left standstill 5-7 hour in 28-38 ℃ of environment, allow moisture evenly distributes in the fruit, to exosmosis;

(4) dehumidifier: above-mentioned fruit is placed except moist chamber, and except 28-38 ℃ of moist chamber operating temperature, equipment humidity control 8-10% dehumidified time 5-7 hour, obtained the preserved fruit of water content 15-18%.