阅读说明：本技术 一种低糖风味果脯的制备工艺 (Preparation process of low-sugar flavored preserved fruit ) 是由 马钦元 高秀珍 魏浩 刘志坤 陈见 于 2021-01-15 设计创作，主要内容包括：本发明属于食品饮料加工技术领域,具体涉及一种低糖风味果脯的制备工艺。本发明提供的果脯制备工艺将水果榨汁后添加木糖经酶解后由黑曲霉发酵产柠檬酸所得清液作为糖渍液所需溶剂,可以实现果脯的高效、高质糖渍,在保留水果天然风味的同时,增加了水果和木糖酶解、发酵代谢组分的特征风味,解决传统水果果脯口味单一、色泽差、高糖果脯引起的肥胖、高血糖等问题,提高了水果果脯产品的营养、保健价值,具有良好的工业应用价值。(The invention belongs to the technical field of food and beverage processing, and particularly relates to a preparation process of low-sugar flavored preserved fruits. According to the preparation process of the preserved fruit, the fruit is juiced, xylose is added, the Aspergillus niger is fermented after enzymolysis to produce the clear liquid of citric acid, and the clear liquid is used as a solvent required by the sugaring liquid, so that high-efficiency and high-quality sugaring of the preserved fruit can be realized, the natural flavor of the fruit is kept, the characteristic flavors of the fruit, xylose enzymolysis and fermentation metabolic components are increased, the problems of single taste, poor color and luster of the traditional preserved fruit, obesity, hyperglycemia and the like caused by the high-sugar preserved fruit are solved, the nutrition and health care values of the preserved fruit are improved, and the preparation process has a good industrial application value.)

1. A preparation process of preserved fruit is characterized in that the adopted sugaring liquid solvent is prepared by the following steps: squeezing fruits, adding water to adjust solid content to 15-20%, directly adding xylose mother liquor without filtering, adjusting the mixing ratio of fruit juice and xylose mother liquor to 3.5-8.0:1, adding carbohydrate hydrolase, and performing enzymolysis until the content of reducing sugar reaches 12-18.5%; then carrying out protease enzymolysis until the content of soluble protein reaches 0.2-0.35%; heating to 85-95 deg.C after enzymolysis, and maintaining for 20-40min to obtain enzymolysis solution; inoculating Aspergillus niger capable of fermenting to produce citric acid to perform citric acid fermentation until the fermentation produces 3-7g/L of acid, and filtering with diatomite plate frame to obtain clear liquid as solvent for sugar solution.

2. A process according to claim 1, wherein the carbohydrate hydrolyzing enzyme includes but is not limited to at least one of amylase, saccharifying enzyme, pectinase, cellulase and xylanase.

3. A process according to claim 1, wherein the conditions of hydrolysis by carbohydrate hydrolyzing enzymes are: the enzymolysis temperature is 30-60 ℃, and the enzymolysis time is 2-8 h; and (3) protease enzymolysis conditions: the enzymolysis temperature is 40-60 ℃, and the enzymolysis time is 1-4 h.

4. The process of claim 1, wherein the aspergillus niger fermentation conditions are: the inoculation amount is 3-7%, the fermentation temperature is 35-38 ℃, and the fermentation time is 20-26 h.

5. A process according to claim 4, wherein Aspergillus niger is Aspergillus CICC2089, Aspergillus BNCC336179 or Aspergillus BNCC 336180.

6. A process for preparing preserved fruit as claimed in claim 1, wherein sucrose is added to the prepared sugar solution solvent to prepare a sugar solution with a total sugar degree of 30-45%.

7. A process according to claim 6, wherein the fruit or fruit pieces are soaked in the sugaring liquid;

vacuum degree of-0.06-0.08 MPa, temperature of 60-90 deg.C, and time of 20-40 min; then releasing the vacuum to normal pressure, keeping the temperature at 60-90 ℃ for 10-30 min; intermittent vacuum circulation is carried out for 3-5 times.

8. The process for preparing preserved fruit according to claim 7, wherein the flavored preserved fruit is obtained by baking the sugared fruit at 55-65 ℃ for 8-12 hours.

The technical field is as follows:

the invention belongs to the technical field of food and beverage processing, and particularly relates to a preparation process of low-sugar flavored preserved fruits.

Background art:

the preserved fruit is a product which is made of fruits and vegetables as raw materials by processes of sugaring, drying and the like, has slight transparent feeling and has no sugar cream separated out on the surface. The preserved fruit has more than 2000 years of history in China, is a special traditional food in China, can be directly eaten, can also be added into other foods for decorating or improving the flavor, and is widely popular with consumers. More importantly, the processing of the preserved fruits provides a way for developing and utilizing fruit and vegetable resources and improving the added value of the fruits and vegetables. However, with the improvement of living standard and health care consciousness of people, the requirements of people on food are gradually improved. The traditional preserved fruits which are mainstream in the market at present have the problems of high sugar degree, single taste, poorer product color, transparency and plumpness, short shelf life and the like.

After the fruits and vegetables are subjected to enzymolysis, the nutritive value and the palatability of the fermented fruits and vegetables can be directly improved, components with specific flavor and functional characteristics, such as organic acid, vitamins, amino acids, antioxidant substances and the like, are generated, and the fermented fruits and vegetables have the effects of maintaining the balance of intestinal flora, promoting the digestion and absorption of human bodies, resisting oxidation and aging, improving the immunity of the human bodies, preventing cardiovascular diseases and the like. The xylose mother liquor is a byproduct generated in the industrial production process of xylose, has high total sugar content, mainly contains xylose, and also contains a small amount of arabinose and glucose. Usually, about 1.5t of xylose mother liquor is produced every 1t of crystalline xylose produced, and the xylose has the functions of optimizing intestinal flora, promoting intestinal health, reducing inflammation, improving immune function, improving lipid metabolism and the like. The citric acid is an acidulant, has good antibacterial and antiseptic effects, and has good effects of improving the taste and flavor of the product and prolonging the shelf life.

According to the invention, enzymolysis of key components of fruits and vegetables, xylose mother liquor and citric acid fermentation are introduced into traditional preserved fruit production, so that the nutritional ingredients of the fruits can be preserved, the special effects of the enzymolysis and fermentation components are achieved, the product flavor is improved, the citric acid and xylose which produce acid by fermentation have good antibacterial and antiseptic effects, and the problem of product quality guarantee period reduction caused by product sugar degree reduction can be effectively relieved. The problems of obesity, hyperglycemia and the like caused by the traditional preserved fruit with single taste and poor color and high sugar content are solved, the health care value of the preserved fruit product is improved, the product market development prospect is wide, and the preserved fruit product is bound to become a hotspot and development direction of the research of the preserved fruit industry.

The invention content is as follows:

aiming at the defects of the prior art, the invention aims to provide a preparation process of flavored preserved fruits, which mainly relates to the preparation of a sugaring solution and intermittent vacuum sugar-permeation dehydration. The preparation process of the preserved fruit provided by the invention can realize high-efficiency and high-quality sugaring of the preserved fruit, increase the characteristic flavor of fruit and xylose enzymolysis and fermentation metabolic components while keeping the natural flavor of the fruit, solve the problems of single taste, poor color and luster of the traditional preserved fruit, obesity, hyperglycemia and the like caused by the high-sugar preserved fruit, improve the nutrition and health care value of the preserved fruit product, and have good industrial application value.

The preparation process of the preserved fruit provided by the invention comprises the following specific steps:

(1) preparation of sugaring liquid solvent

Squeezing fruits, adding water to adjust the solid content to 15-20%, directly adding xylose mother liquor without filtering, adjusting the mixing ratio of the fruit juice to the xylose mother liquor to be 3.5-8.0:1(v/v), adjusting the solid content of the xylose mother liquor to be 50-60%, and then adding carbohydrate hydrolase for enzymolysis until the content of reducing sugar reaches 12-18.5%;

the carbohydrate hydrolyzing enzyme includes but is not limited to at least one of amylase, saccharifying enzyme, pectinase, cellulase and xylanase;

and (3) enzymolysis conditions: the enzymolysis temperature is 30-60 ℃, and the enzymolysis time is 2-8 h;

then carrying out protease enzymolysis at 40-60 deg.C for 1-4h until the soluble protein content reaches 0.2-0.35%; heating to 85-95 deg.C after enzymolysis, and maintaining for 20-40min to obtain enzymolysis solution;

inoculating Aspergillus niger capable of fermenting to produce citric acid to the enzymolysis liquid for citric acid fermentation, wherein the inoculation amount is 3-7%, the fermentation temperature is 35-38 ℃, the fermentation time is 20-26h, the fermentation acid is 3-7g/L, and filtering is carried out by using a diatomite plate frame to obtain a clear liquid which is a solvent required by the sugar soaking liquid;

further, the aspergillus niger is aspergillus niger CICC2089, aspergillus niger BNCC336179, aspergillus niger BNCC336180 and the like;

(2) intermittent vacuum sugar-soaking dehydration

Preparing a sugar soaking liquid: adding sucrose into the prepared sugar solution solvent to obtain sugar solution with total sugar degree of 30-45% (w/w).

Sugar soaking: submerging the fruit or fruit slices with the sugaring liquid;

vacuum degree of-0.06-0.08 MPa, temperature of 60-90 deg.C, and time of 20-40 min;

then releasing the vacuum to normal pressure, keeping the temperature at 60-90 ℃ for 10-30 min;

adjusting vacuum to-0.06-0.08 MPa again, and intermittently vacuum-circulating for 3-5 times, wherein the total time of sugaring is 90-350 min.

(3) And (3) post-treatment: and (3) baking the sugared fruits for 8-12 hours at the temperature of 55-65 ℃ to obtain the preserved fruits with good quality and flavor.

Has the advantages that:

1. the invention realizes the purposes of reducing the sugar degree of the product and simultaneously ensuring the appearance of the product by adjusting the composition of the sugaring liquid, reducing the sucrose concentration of the sugaring liquid, increasing the content of functional sugar and adjusting the sugaring process;

2. according to the invention, the xylose mother liquor with an antibacterial effect and citric acid produced by self fermentation of fruits are added to play a good antibacterial effect, so that the problem that the quality guarantee period of the preserved fruit product cannot be maintained due to low sugar degree is solved;

3. according to the invention, through the optimization of the composition of the sugar soaking liquid, functional sugar components such as xylose and the like are added on the basis of the original sucrose, and meanwhile, on the basis of the original components of the fruit, the compositions of soluble sugar, soluble protein and fermentation metabolites are increased through enzymolysis and aspergillus niger fermentation, so that the product has better and superior flavor, and is richer in nutrition and easy to absorb.

Description of the drawings:

FIG. 1 shows the variation of different groups of sugars.

The specific implementation mode is as follows:

the present invention will be further described with reference to the following specific examples. It should be understood that the following examples are illustrative only and are not intended to limit the scope of the present invention.

Experimental group 1: adding xylose mother liquor and aspergillus niger for fermentation

Dividing the hawthorn into two parts, and removing kernels from one part for later use; squeezing the other part of hawthorn, adding water to adjust the solid content to 16%, adding 55% xylose mother liquor into the pulp according to the volume ratio of 8:1, stirring uniformly, and then heating to 58 ℃ to naturally adjust the pH value; adding alpha-amylase (EC3.2.1.1.), wherein the enzyme activity of the alpha-amylase is 36000U/g, and the addition amount is 8U/mL; adding saccharifying enzyme (E.C.3.2.1.3), wherein the enzyme activity of saccharifying enzyme is 260000U/g, and the addition amount is 100U/mL; adding xylanase, wherein the enzyme activity of the xylanase is 42000U/g, and the addition amount is 40U/mL; after 8 hours of enzymolysis, the content of reducing sugar is 14.5%, papain (E.C.3.4.22.2) is added, the enzyme activity of the papain is 800000U/g, the addition amount is 200U/mL, and the content of soluble protein is 0.25% after 4 hours of enzymolysis. And then heating to 95 ℃ for 40min to inactivate enzyme, cooling to 35 ℃, inoculating Aspergillus niger CICC2089 with the inoculation amount of 6%, wherein the Aspergillus niger fermentation seed liquid culture medium is consistent with the fermentation culture medium, the fermentation temperature is 35 ℃, the fermentation time is 26h, the fermentation acid yield is 5.3g/L, and the diatomite plate frame is filtered to obtain clear liquid.

Adding sucrose into the clear solution to obtain sugaring solution with total sugar degree of 40%.

The sugaring process conditions are as follows: removing core of fructus crataegi, soaking in sugar solution under vacuum degree of-0.08 MPa and temperature of 70 deg.C for 30 min; releasing vacuum to normal pressure, keeping the temperature at 70 ℃ for 20 min; intermittent vacuum was repeated 5 times.

And (3) drying the sugared hawthorn slices at 65 ℃ for 8 hours to obtain the low-sugar flavored preserved hawthorn 1 with excellent quality.

Experimental group 2: aspergillus niger only fermentation

Dividing the hawthorn into two parts, and removing kernels from one part for later use; squeezing the other part of fructus crataegi, adding alpha-amylase (EC3.2.1.1.), wherein the enzyme activity of alpha-amylase is 36000U/g, and the addition amount is 8U/mL; adding saccharifying enzyme (E.C.3.2.1.3), wherein the enzyme activity of saccharifying enzyme is 260000U/g, and the addition amount is 100U/mL; and adding papain (E.C.3.4.22.2) after enzymolysis for 8h, wherein the enzyme activity of the papain is 800000U/g, the addition amount is 200U/mL, and enzymolysis is carried out for 4 h. Then heating to 95 ℃ and maintaining for 40min, cooling to 35 ℃, inoculating Aspergillus niger CICC2089 with the inoculation amount of 6%, fermenting at 35 ℃, fermenting for 26h, producing acid by fermentation of 5.5g/L, and filtering by a diatomite plate frame to obtain clear liquid. Adding sucrose into the clear solution to obtain sugaring solution with total sugar degree of 40%. The sugaring process conditions are as follows: removing core of fructus crataegi, soaking in sugar solution under vacuum degree of-0.08 MPa and temperature of 70 deg.C for 30 min; releasing vacuum to normal pressure, keeping the temperature at 70 ℃ for 20 min; intermittent vacuum was repeated 5 times. And (3) drying the sugared hawthorn slices at 65 ℃ for 8 hours to obtain the flavored preserved hawthorn 2.

Experimental group 3: fermenting sucrose instead of xylose mother liquor and aspergillus niger

Dividing the hawthorn into two parts, and removing kernels from one part for later use; squeezing the other part of hawthorn, adding water to adjust the solid content to 16%, adding sucrose solution with the solid content of 55% into the pulp according to the volume ratio of 8:1, stirring uniformly, then heating to 58 ℃, and naturally adjusting the pH value; adding alpha-amylase (EC3.2.1.1.), wherein the enzyme activity of the alpha-amylase is 36000U/g, and the addition amount is 8U/mL; adding saccharifying enzyme (E.C.3.2.1.3), wherein the enzyme activity of saccharifying enzyme is 260000U/g, and the addition amount is 100U/mL; and adding papain (E.C.3.4.22.2) after enzymolysis for 8h, wherein the enzyme activity of the papain is 800000U/g, the addition amount is 200U/mL, and enzymolysis is carried out for 4 h. Then heating to 95 ℃ and maintaining for 40min, cooling to 35 ℃, inoculating Aspergillus niger CICC2089 with the inoculation amount of 6%, fermenting at 35 ℃, fermenting for 26h, producing acid by fermentation of 5.7g/L, and filtering by a diatomite plate frame to obtain clear liquid. Adding sucrose into the clear solution to obtain sugaring solution with total sugar degree of 40%. The sugaring process conditions are as follows: removing core of fructus crataegi, soaking in sugar solution under vacuum degree of-0.08 MPa and temperature of 70 deg.C for 30 min; releasing vacuum to normal pressure, keeping the temperature at 70 ℃ for 20 min; intermittent vacuum was repeated 5 times. And (3) drying the sugared haw slices at 65 ℃ for 8 hours to obtain the flavored preserved haw 3.

Control group 1: adding xylose mother liquor only for enzymolysis

Dividing the hawthorn into two parts, and removing kernels from one part for later use; squeezing the other part of hawthorn, adding water to adjust the solid content to 16%, adding 55% xylose mother liquor into the pulp according to the volume ratio of 8:1, stirring uniformly, and then heating to 58 ℃ to naturally adjust the pH value; adding alpha-amylase (EC3.2.1.1.), wherein the enzyme activity of the alpha-amylase is 36000U/g, and the addition amount is 8U/mL; adding saccharifying enzyme (E.C.3.2.1.3), wherein the enzyme activity of saccharifying enzyme is 260000U/g, and the addition amount is 100U/mL; adding xylanase, wherein the enzyme activity of the xylanase is 42000U/g, and the addition amount is 40U/mL; and adding papain (E.C.3.4.22.2) after enzymolysis for 8h, wherein the enzyme activity of the papain is 800000U/g, the addition amount is 200U/mL, and enzymolysis is carried out for 4 h. Then heating to 95 deg.C for 40min, and filtering with diatomite plate frame to obtain clear liquid. Adding sucrose into the clear solution to obtain sugaring solution with total sugar degree of 40%. The sugaring process conditions are as follows: removing core of fructus crataegi, soaking in sugar solution under vacuum degree of-0.08 MPa and temperature of 70 deg.C for 30 min; releasing vacuum to normal pressure, keeping the temperature at 70 ℃ for 20 min; intermittent vacuum was repeated 5 times. And (3) drying the sugared hawthorn slices at 65 ℃ for 8 hours to obtain flavored preserved hawthorn 4.

Control group 2: preserved normal hawthorn

Removing core from fructus crataegi, and directly sugaring. The sugaring liquid is a 50% sucrose solution, and the sugaring process conditions are as follows: the vacuum degree is-0.08 MPa, the temperature is 70 ℃, and the time is 30 min; releasing vacuum to normal pressure, keeping the temperature at 70 ℃ for 20 min; intermittent vacuum was repeated 5 times. And (3) drying the sugared hawthorn slices at 65 ℃ for 8 hours to obtain the preserved hawthorn 5.

Example 2 comparison of mouthfeel, flavor and physicochemical indices

Table 1: sensory evaluation table for preserved fruit

Table 2: sensory evaluation comparison

Experimental group	Condition	Color	Taste of the product	Degree of fullness	Total score
						Experimental group 1	Adding xylose mother liquor and aspergillus niger for fermentation	28	26	32	86
Experimental group 2	Aspergillus niger only fermentation	24	24	31	79
						Experimental group 3	Fermenting sucrose instead of xylose mother liquor and aspergillus niger	25	23	32	80
Control group 1	Adding xylose mother liquor only for enzymolysis	27	19	30	76
						Control group 2	Preserved normal hawthorn	24	18	32	74

Table 3: comparison of physical and chemical indexes

Remarking: detecting according to NY/T436-2018 industry standard

Table 4: comparison of stability test

Experimental group

4 weeks

8 weeks

For 12 weeks

For 16 weeks

For 20 weeks

24 weeks

Experimental group 1

Without change

Without change

Without change

Without change

Without change

Without change

Experimental group 2

Without change

Without change

Without change

Without change

Without change

Mildew point appears

Experimental group 3

Without change

Without change

Without change

Without change

Without change

Mildew point appears

Control group 1

Without change

Without change

Without change

Without change

Mildew point appears

AppearMildew spot

Control group 2

Without change

Without change

Without change

Without change

Without change

Without change

Remarking: accelerated stability test conditions: the product is placed in a natural environment with the temperature of 30 ℃ and the humidity of 70 percent, and samples are taken every 4 weeks to observe the change of texture, color and smell.

The results show that the low-sugar preserved fruit with the flavor of low sugar prepared by the invention has the advantages of uniform color, brightness, moderate sweetness, good toughness, sufficient flavor, full tissue and no cracking, the total sugar content is lower than that of the common preserved fruit, the content of fructose and functional sugar is obviously increased, the content of sucrose is reduced, the shelf life is not reduced, the preserved fruit has better sense and has more health care function than the common preserved fruit, and the specific sugar composition is shown in figure 1.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.