Preparation Process of High-Quality Apple Jam

Abstract

The present invention relates to a preparation method of high-quality apple jam. The preparation method integrates crushing, pulping and steam enzyme deactivation, and immediately adopts ultra-fast cooling after pulping and enzyme deactivation. The ultra-fast cooling integrates vacuum cooling and chilled brine conduction cooling. The whole technological process features strict control over parameters, retention of the original color, luster, flavor and nutrients. The present invention includes the following procedures: quality control of raw materials, namely apples, combination of crushing, pulping and steam enzyme deactivation, ultra-fast cooling, filtration, separation, multi-effect low-temperature concentration, formulating, canning, sterilization and fast cooling. The preparation process of the present invention not only greatly reduces the enzymatic browning of the polyphenol oxidase, but also effectively avoids losses of its flavor and nutrients such as sugar, proteins, mineral substances and etc., obtaining high-quality apple jam with excellent color, and taste and therefore having a huge market promotion value.

Claims

1. A preparation method of high-quality apple jam, comprising: (1) selecting raw material and pre-treatment: selecting apples as raw material, washing the apples clean and cutting the apples into sections. (2) crushing, pulping and steam enzyme deactivation integration: crushing and pulping the apples treated in step (1), wherein steam is sprayed to the apples during crushing and pulping, such that pulp temperature rises to 82-92 C. within 1-3 min; then the steam spraying is stopped, and the pulp temperature is kept at 82-92 C. for 42-12 s; (3) ultra-fast cooling: quickly cooling the apple pulp obtained in step (2) by combining vacuum cooling and chilled brine conduction cooling, wherein the temperature quickly declines to below 40 C. within 2-3 min; (4) post-treatment: filtering the apple pulp prepared in step (3) to remove kernels and then undergoes multi-effect concentration at a low temperature; formulating, canning, sterilizing and cooling the concentrated pulp, and then obtaining finished products.

2. The preparation method according to claim 1, wherein the raw material selected in step (1) are fresh and mature qualified apples without mould, decay, insect and peptide residue; a sugar degree of the apples is greater than 12 Brix; a bubbling cleaner is adopted to wash the apples; and each one of the apples is cut into 4-8 sections after washing.

3. The preparation method according to claim 1, wherein a predetermined time before crushing is carried out in step (2), inputting the steam in advance to exhaust air in a crushing cavity; homogeneously spraying the steam to the crushed apples; final temperature after temperature rise and the maintaining time of the final temperature follow a linear inverse relation: T=t/3+96, wherein T represents the final temperature, in unit of C.; t represents the maintaining time, in unit of s.

4. The preparation method according to claim 1, wherein vitamin C or citric acid which accounts for 0.006-0.05% of mass of the apples, is added during crushing and pulping.

5. The preparation method according to claim 1, wherein a fast revolving blade tool is adopted in step (2) to crush the apples to about 2 mm.

6. The preparation method according to claim 1, wherein a pressure of the steam sprayed in step (2) is 0.15-0.30 MPa.

7. The preparation method according to claim 1, wherein in step (3), pumping the apple pulp obtained in step (2) into a vacuum cooler and then the pulp descends in a film state, wherein the vacuum cooler is a centrifugal scraper type film evaporator, and a jacket of the evaporator is filled with chilled brine.

8. The preparation method according to claim 7, wherein in step (3), a vacuum degree during vacuum cooling is 0.085-0.1 MPa, and temperature of the chilled brine in the jacket is less than 4 C.

9. The preparation method according to claim 1, wherein in step (4), concentrating the filtered apple pulp by using a film-descending type four-effect evaporator, wherein a first-effect temperature is 50-60 C.; a second-effect temperature is 42-50 C.; a third-effect temperature is 35-42 C.; a fourth-effect temperature is 25-35 C.; and a content of soluble solids in the apple pulp is 60-75 Brix after concentration.

10. The preparation method according to claim 1, wherein in step (4), carrying out the sterilization in a high-pressure sterilizing boiler; the sterilizing temperature in a center of the pulp reaches 90-98 C. and is kept at such temperature for 4-7 min; after being discharged from the boiler, spraying the pulp with cold water to be cooled to the normal temperature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a schematic structural diagram of a vacuum cooler used in a preferred solution of the present invention.

[0025] In FIG. 1, 1. scraper; 2. inner barrel; 3. jacket; 4. distributing round plate; 5. baffle; 6. motor; A. vacuuming port; B. feed port; C. coolant outlet; D. coolant inlet; E. discharge opening

DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention is described in detail below in conjunction with the attached drawings and embodiment. The embodiment, implemented on the premise of the technical solution of the present invention, provides the detailed implementation means and specific operation process on the basis of this technical solution, but the protective scope of the present invention is not limited to the following embodiment.

Embodiment 1

[0027] (1) Raw material selection and treatment: Fresh and relatively mature Fuji apples without mould, decay, insects and pesticide residues are selected as raw materials with a sugar degree of greater than 12 Brix; the raw materials are washed clean;

[0028] (2) Cutting: Every apple is cut into 4 sections to facilitate the subsequent crushing, pulping and enzyme deactivation integrated treatment;

[0029] (3) Crushing, pulping and enzyme deactivation integrated treatment: During apple crushing, the steam with a pressure of about 0.15 MPa is sprayed onto the apples which are being crushed, such that the pulp temperature quickly rises to 86 C. within 2 min and is kept at 86 C. for 30 s;

[0030] (4) Ultra-fast cooling: the pulp obtained after the steam heating type enzyme deactivation and crushing procedures is pumped into a centrifugal scraper type film vacuum evaporator such that the pulp descends in a film state; the jacket of the evaporator is filled with chilled brine, wherein the vacuum degree is 0.092 MPa; the temperature of the chilled brine is 10 C.; finally, the pulp is quickly cooled to room temperature within 2.5 min while being de-gasified;

[0031] (5) Filtration: A screen with an aperture of 2 mm is adopted to filter out apple kernels;

[0032] (6) Low-temperature concentration: the de-gasified apple pulp is concentrated at a low temperature by using a film-descending type four-effect evaporator, wherein a first-effect temperature is 50 C.; a second-effect temperature is 42 C.; a third-effect temperature is 35 C.; a fourth-effect temperature is 25 C.; after four-effect treatment, the content of the soluble solids in the concentrated apple pulp is 60 Brix (refractometry at a temperature of 20 C.);

[0033] (7) Formulating: 5% cane sugar, 1.5% gelatin solution which is prepared in advance and 0.03% vitamin C are added;

[0034] (8) Blending and stirring: the materials mixed in step (7) are blended with the concentrated apple pulp obtained in step (6) and the mixture is stirred homogeneously;

[0035] (9) Canning: The pulp jam obtained in step (8) is canned to obtain finished products;

[0036] (10) Sterilization: A sterilization reactor is adopted to sterilize the finished products; the temperature in the sterilizing center is 98 C.; the sterilization time is 4 min; and the canned jam is quickly cooled to about 35 C. by means of spraying after sterilization.

Embodiment 2

[0037] (1) Raw material selection and treatment: Fresh and relatively mature Fuji apples without mould, decay, insects and pesticide residues are selected as raw materials with a sugar degree of greater than 12 Brix; the raw materials are washed clean;

[0038] (2) Cutting: Every apple is cut into 6 sections to facilitate the subsequent crushing, pulping and enzyme deactivation integrated treatment;

[0039] (3) Crushing, pulping and enzyme deactivation integrated treatment: During apple crushing, steam with a pressure of about 0.20 MPa is sprayed onto the apples which are being crushed, such that the pulp temperature quickly rises to 90 C. within 1 min and is kept at 90 C. for 18 s;

[0040] (4) Ultra-fast cooling: the pulp obtained after the steam heating type enzyme deactivation and crushing procedures is pumped into a centrifugal scraper type film vacuum evaporator such that the pulp descends in a film state; the jacket of the evaporator is filled with chilled brine, wherein the vacuum degree is 0.098 MPa; the temperature of the chilled brine is 6 C.; finally, the pulp is quickly cooled to room temperature within 3 min while being de-gasified;

[0041] (5) Filtration: A screen with an aperture of 2 mm is adopted to filter out apple kernels;

[0042] (6) Low-temperature concentration: the de-gasified apple pulp is concentrated at a low temperature by using a film-descending type four-effect evaporator, wherein the first-effect temperature is 60 C.; the second-effect temperature is 50 C.; the third-effect temperature is 42 C.; the fourth-effect temperature is 35 C.; after four-effect treatment, the content of the soluble solids in the concentrated apple pulp is 75 Brix (refractometry at a temperature of 20 C.);

[0043] (7) Formulating: 4% honey (with a moisture content of about 20%), 5% Arabic gum which is prepared in advance and 0.03% citric acid are added;

[0044] (8) Blending and stirring: the materials mixed in step (7) are blended with the concentrated apple pulp obtained in step (6) and the mixture is stirred homogeneously;

[0045] (9) Canning: The pulp jam obtained in step (8) is canned to obtain finished products;

[0046] (10) Sterilization: A sterilization reactor is adopted to sterilize the finished products; the temperature in the sterilizing center is 92 C.; the sterilization time is 6 min; and the canned jam is quickly cooled to about 35 C. by spraying after sterilization.

Embodiment 3

[0047] (1) Raw material selection and treatment: Fresh and relatively mature Fuji apples without mould, decay, insects and pesticide residues are selected as raw materials with a sugar degree of greater than 12 Brix; the raw materials are washed clean;

[0048] (2) Cutting: Every apple is cut into 8 sections to facilitate the subsequent crushing, pulping and enzyme deactivation integrated treatment;

[0049] (3) Crushing, pulping and enzyme deactivation integrated treatment: During apple crushing, the steam with a pressure of about 030 MPa is sprayed onto the apples which are being crushed, such that the pulp temperature quickly rises to 82 C. within 1 min and is kept at 82 C. for 42 s;

[0050] (4) Ultra-fast cooling: the pulp obtained after the steam heating type enzyme deactivation and crushing procedures is pumped into a centrifugal scraper type film vacuum evaporator such that the pulp descends in a film state; the jacket of the evaporator is filled with chilled brine, wherein the vacuum degree is 0.085 MPa; the temperature of the chilled brine is 8 C.; finally, the pulp is quickly cooled to room temperature within 2 min while being e-gasified;

[0051] (5) Filtration: A screen with an aperture of 2 mm is adopted to filter out apple kernels;

[0052] (6) Low-temperature concentration: the de-gasified apple pulp is concentrated at a low temperature by using a film-descending type four-effect evaporator, wherein the first-effect temperature is 55 C.; the second-effect temperature is 46 C.; the third-effect temperature is 39 C.; the fourth-effect temperature is 30 C.; after four-effect treatment, the content of the soluble solids in the concentrated apple pulp is 65 Brix (refractometry at a temperature of 20 C.);

[0053] (7) Formulating: 7% (w/w) of cane sugar, a proper amount of 1.5% (w/w) gelatin solution prepared in advance and 0.03% (w/w) vitamin C are added;

[0054] (8) Blending and stirring: the materials mixed in step (7) are blended with the concentrated apple pulp obtained in step (6) and the mixture is stirred homogeneously;

[0055] (9) Canning: The pulp jam obtained in step (8) is canned to obtain finished products;

[0056] (10) Sterilization: A sterilization reactor is adopted to sterilize the finished products; the temperature in the sterilizing center is 90 C.; the sterilization time is 7 min; and the canned jam is quickly cooled to about 35 C. by spraying after sterilization.

[0057] By adopting the basic technical solution of embodiment 2 and changing some of the steps, contrast examples 1-4 are obtained as below:

[0058] In contrast example 1, the pulping operation in step (3) and in step (4) of embodiment 2 is changed to natural pulping by using a pulping machine;

[0059] In contrast example 2, the pulping operation in step (3) of embodiment 2 is changed to natural pulping using a pulping machine, and then the pulp quickly undergoes enzyme deactivation at a temperature of 90 C. for 15 s;

[0060] In contrast example 3, the pulp in step (4) of embodiment 2 is naturally cooled to room temperature;

[0061] In contrast example 4, the pulp in step (4) of embodiment 2 is pumped into a vacuum cooler, and the scraper does not rotate while the vacuum coolers perform vacuuming to cool the pulp to room temperature.

[0062] The products obtained in embodiments 1-3 and the products obtained in contrast examples 1-4 were measured, and indices such as sensory assessments, browning and polyphenol content were respectively compared. Below are the details.

[0063] (1) The scoring criteria of the sensory assessments can be seen in Table 1. Seven samples were taken from the embodiments 1-3 and the contrast examples 1-4; every sample was divided into five parts; the assessments were carried out three times and the average value was used. The color, smell, taste and general feeling of the apple jam were assessed and scored. The full score is 100 points.

TABLE-US-00001 TABLE 1 Sensory assessment scoring table of the apple jam Luster The jam has The jam has Has a little The color is The product attractive the natural color of the inappropriate, luster is natural luster luster of the jam, but the but does not mixed or the of the jam jam, but the visual effect affect the luster is (25-21 points) luster is not is not obvious product unpleasant obvious (15-11 points) appearance (5-1 points) (20-16 points) (10-6 points) Smell The jam has a The jam has The jam has The jam has The jam does strong apple an apple an apple an aroma not have a smell which smell which smell which which is jam aroma, matches the matches the matches with similar to the and but has a unique aroma unique aroma the unique apple aroma, strongly of the apple of the apple aroma of the but also has a terrible smell jam, and has a jam, and the apple jam, but little terrible (5-1) full aroma aroma is soft the aroma is smell (10-6 (25-21 points) but slight not soft points) (20-16 points) (15-11 points) Taste The jam has a The jam has The jam has The jam has a Incorrect strong apple an apple jam an apple jam little apple flavor, jam taste taste which is taste which is jam taste terrible taste (25-21 points) soft (20-16 not which is too (5-1 point) points) homogeneous light to (15-11 points) maintain (10-6 points) General The product The product The product The product The product assessments gains an gains a good gains a gains a poor gains a very excellent general medium general bad general general assessment general assessment assessment assessment result, and is assessment result, and is result, and is result, and is relatively result and is relatively rejected (5-1 very popular popular generally unpopular points) (25-21 points) (20-16 points) popular (10-6 points) (15-11 points)

[0064] Apple browning is classified into enzymatic browning and non-enzymatic browning; and the main browning is enzymatic browning, usually completed within 10 min after apples are crushed. The pulp color and the variable value L of the color along with the time are measured, and different treatment methods are employed to determine and compare the luster of the apple pulp. The larger the value L is, the brighter the pulp is; vice versa. The anti-browning effect of sodium metabisulfite is good, so apple pulp added with 2% (w/w) sodium metabisulfite is used as a standard sample.

[0065] During the determination of the value L, a HunterLab (model UltraScanPro1166, American company HunterLab) colorimeter is usually used to determine the juice color, and the data results are represented by L, a and b. A standard white board is used to carry out verification first. Then, a cylindrical sample machine (58 mm diameter and 15 mm depth) containing pulp of the same mass is placed under the aperture (50 mm diameter) of the colorimeter, wherein L is called brightness index. L=0 represents black, L=100 represents white; wherein a and a respectively represent red and green, the larger the absolute value of a is, the more the colors respectively approach pure red and pure green, the color is grey when a=0; wherein b and b respectively represents yellow and blue, the larger the absolute value of b is, the more the colors respectively approach pure yellow and pure blue, and the color is gray when b=0.

[00001]$\mathrm{Relative}.Math..Math.\mathrm{browning}.Math..Math.\mathrm{rate}=\frac{L_{\mathrm{control}}-L_{\mathrm{sample}}}{L_{\mathrm{control}}-L_{\mathrm{nature}}}.Math.$

[0066] L.sub.controlValue L (which basically does not change along with time) of the pulp generated after the apples added with 2% sodium metabisulfite are crushed and pulped;

[0067] L.sub.natureValue of the apple pulp kept for 10 min after the apples are naturally crushed and pulped;

[0068] L.sub.sampleValue L of the apple pulp after the apple pulp prepared in embodiments 1-3 and contrast examples 1-4 is placed for 10 min.

[0069] (3) Polyphenols are substances which determine the flavor and color of apples and apple products, having a close relationship with the sensory qualities of apples and products thereof. Apple polyphenols mainly include catechinic acids, proanthocyanidins, hydroxycinnamic acids, dihydrochalcone, flavonol and anthocyanin types.

[0070] Folin-reagent method for determination of the total amount of polyphenols: (1) Standard curve making: 100 g/mL 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30 mL of gallic acid standard solutions are respectively accurately absorbed and placed in 5 mL volumetric flasks; 1.95, 1.90, 1.85, 1.80, 1.75 and 1.70 mL of distilled water is respectively added into the corresponding volumetric flasks, and followed by 1.0 mL of folin reagent; the mixed materials are fully shaken and then kept still for 3-4 min; 1.0 ml of 10% Na.sub.2CO.sub.3 solution is respectively added into the volumetric flasks; and the mixtures are fully shaken and placed in a constant-temperature water-bath and react for 7 h. Meanwhile, a control group without reagent is made; absorbency is determined at a bandwidth of 765 nm; and linear regression of the absorbancy is carried out by using the content to obtain a regression equation. (2) Raw material treatment: 5.000 g of apple pulp is accurately weighed and placed in a conical flask; 80 ml of 70% ethanol is added; thermal refluxing extraction carried out three times in an 80 C. water-bath, 2 h each time; the mixture is centrifuged for 20 min at a speed of 4,000 r/min; the supernate is collected and merged; the emerged supernate is concentrated in a rotary evaporator at a pressure of 0.09 MPa while ethanol is recycled; and the concentrated solution is added with distilled water to fix the volume to 50 mL, and the prepared solution is kept for later determination.

[0071] Determination principle and method: polyphenol compound molecules have hydroxy which is very easily oxidized, and reacts with the Folin-Ciocalten reagent in alkaline conditions; the reaction product is blue, and has the maximum absorbency at the bandwidth of 765 nm; the reaction product follows the Lambert-beer's law in certain conditions; the total amount of the apple polyphenols can be determined by using gallic acid as a reference substance. According to such determination principle, 2 mL of the solution is absorbed from the 50 mL of solution to be determined; the absorbency is determined by using the standard curve making method; the polyphenol content in the 2 mL of solution to be determined is calculated according to the regression equation; and then, the content of the phenolic substances in 1 g of samples is further calculated (based on the gallic acid mg/g, DW).

[0072] The above determination results undergo data processing, and the final results are filled in the table 2 below.

TABLE-US-00002 TABLE 2 Quality evaluation table of the apple jam prepard by using different processing methods Relative Score of the Boiled Processing browning Retention rate of sensory taste or method rate total polyphenols qualities not Contrast 100% 9% 69.6 No Example 1 Contrast 88% 22% 73.1 Yes Example 2 Contrast 3.8% 92.8% 75.1 Yes Example 3 Contrast 3.5% 93.3% 80.8 Yes Example 4 Embodiment 1 2.9% 95.1% 94.6 No Embodiment 2 2.6% 95.4% 95.1 No Embodiment 3 2.5% 96.1% 96.5 No

[0073] In table 2, all raw materials are fresh and mature Fuji apples, and except for a few steps, all other processing links are identical. By analyzing the data in table 2 it can be seen that the traditional processing method in the prior art has the following defects: the pulp obtained using the processing method which includes cold crushing and natural pulping (referring to the contrast example 1) and the pulp obtained using the processing method which includes cold crushing, natural pulping and heating enzyme deactivation (referring to contrast example 2) generate seriously enzymatic browning, obtain the poorest sensory evaluation, and have a very low retention rate of anti-oxidization component, namely polphenols. By using the method of combining crushing, pulping and steam enzyme deactivation, the enzymatic browning is well restrained and the anti-oxidization component, namely polyphenols, is retained to a certain degree, but the natural cooling (referring to the contrast example 3) and the mere vacuuming cooling (referring to the contrast example 4), are not fast enough, and the products have a boiled taste which is difficult to remove after the products are concentrated, so the sensory assessment results are undesirable. Only by adopting the ingenious combination of the crushing and steam enzyme deactivation-integrated method and the ultra-fast cooling method provided by the present invention can the enzymatic browning be well restrained (referring to embodiments 1, 2 and 3), can the anti-oxidization component, namely polyphenols, be retained to be maximum extent, can the products avoid the boiled taste and basically keep the original taste of fruits, and can high-quality apple jam be obtained.

[0074] The above description only involves several ones of the preferred embodiments and does not limit the present invention in any form. Any changes, equivalent changes and modifications made on the basis of the concept of the technical solution of the present invention shall fall within the scope of the technical solution of the present invention.