CN102326653A - 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 drying means of preserved fruit

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 three types of Free water, physical-chemical bond water, chemical bonding water in the fruit.Free water refers to the influence that does not receive material molecule bonding force or structural capacity, and water that can be free movable can be utilized by microorganism.Physical-chemical bond water refers to and fettered by molecule bonding force or structural capacity, water that can not be free movable, and part can be utilized by microorganism.Chemical bonding water refers to the part of molecule, water that can not be free movable, is not utilized by microorganism.Preserved fruit is dry to be evaporated 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 is produced in the preserved fruit production process, fructose are exactly reduced sugar; The branch 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 be with amino acid generation Maillard reaction in the preserved fruit and type of generation melanin or melanin are that product colour deepens even blackening, reduces 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 high more, and sucrose is broken down into reduced sugar more easily, also just destroys the quality of preserved fruit more easily, 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, through 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,, mango fruit fourth adopted cryodesiccated method in producing, 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 banana chip microwave vacuum drying method; 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 the preserved fruit dry with these methods have higher quality, but these methods also have its limitation simultaneously; Adopt freeze-drying method such as preserved fruit, have the shortcoming that investment is big, production capacity is little, energy consumption is big.And the preserved fruit hot-spot that it is drying oven that microwave vacuum drying method is used for the still insurmountable problem of preserved fruit drying 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 in the industrialization of preserved fruit and use.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; Drying time, baking temperature 70-85 ℃, it was big to consume quantity of steam in process of production between 24-72 hour; Time is long, and temperature is high, and 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 occur variable color, the reaction of stream sugar easily, 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

The object of the 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 cost is high-leveled and difficult to drop into the deficiency of large-scale production.

The purpose of foregoing invention realizes that through following technical scheme 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 the above-mentioned dried was left standstill 5-7 hour in 28-38 ℃ of environment, let moisture evenly distributes in the fruit, to exosmosis;

(4) dehumidifier: above-mentioned fruit is placed except that moist chamber, remove 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, is that physical-chemical bond water becomes in the water vapour entering hot-air then, 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 dry air in dehumidifying back; 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, and hot blast uses 55～65 ℃, and 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 the above-mentioned dried was left standstill 5 hours in 28 ℃ of environment, let moisture evenly distributes in the mango, to exosmosis;

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

Embodiment 2

(1) pre-treatment: will be with the pineapple slice of sugar cure to 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 the above-mentioned dried was left standstill 7 hours in 38 ℃ of environment, let moisture evenly distributes in the pineapple, to exosmosis;

(4) dehumidifier: above-mentioned fruit is placed except that moist chamber, remove 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 be with the holy girl fruit of sugar cure to index request, individual layer places on the netted tray, places hothouse;

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

(3) leave standstill: the fruit after the above-mentioned dried was left standstill 6 hours in 30 ℃ of environment, let moisture evenly distributes in the holy girl fruit, to exosmosis;

(4) dehumidifier: above-mentioned holy girl is really placed except that moist chamber, remove 30 ℃ of moist chamber operating temperatures, equipment humidity control 8-10%, obtains the holy girl fruit 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, 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 the above-mentioned dried was left standstill 5-7 hour in 28-38 ℃ of environment, let moisture evenly distributes in the fruit, to exosmosis;

(4) dehumidifier: above-mentioned fruit is placed except that moist chamber, remove 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%.