Preparation method of Chinese wolfberry fruit puree

Abstract

The invention relates to a preparation method of Chinese wolfberry fruit puree, and belongs to the field of Chinese wolfberry fruit puree preparation. Step 2, primary bubbling, floating, cleaning and sterilizing; step 3, secondary bubbling cleaning and sterilization; 4, vibrating, draining, lifting and blow-drying; step 5, hammer type crushing; step 6, carrying out double-pass pulping; step 7, colloid milling; step 8, performing high-pressure homogenization; step 9, preheating and heating; step 10, performing double-effect vacuum concentration; step 11, carrying out vacuum degassing; step 12, performing sleeve type sterilization; step 13, filling; and step 14, carrying out CIP cleaning. The method solves the problems of small-particle unknown substances in the wolfberry primary pulp and fineness of the wolfberry primary pulp, realizes whole-process quality control of the wolfberry primary pulp from raw material treatment to finished product packaging, not only retains nutritional ingredients of wolfberry, but also remarkably improves the sensory quality of the product, and meets the standard requirements of industrial production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of preparation of wolfberry raw pulp, and particularly relates to a preparation method of wolfberry raw pulp. BACKGROUND

[0002] Wolfberry is a traditional Chinese medicine material with the same origin of medicine and food, and is widely used in the field of modern food processing. Its raw pulp products are favored because they retain most of the nutritional components of wolfberry. However, in the traditional preparation process of wolfberry raw pulp, there are generally problems such as incomplete cleaning of raw materials leading to residual impurities, poor sterilization effect affecting product shelf life, severe oxidation browning of raw pulp during processing, broken pulp and uneven homogenization leading to coarse particles affecting taste, and the like. In addition, there are deficiencies in the precise control of auxiliary materials and the automatic cleaning of production equipment. Moreover, the pressure during homogenization is low, and the wolfberry raw pulp completed by the colloid mill is not fine enough, and the extracted raw pulp has small black unknown particles (if the handle). These factors to some extent restrict the quality improvement and industrial production efficiency of wolfberry raw pulp products. SUMMARY

[0003] The present application provides a preparation method of wolfberry raw pulp to solve the defects in the prior art.

[0004] The present application is implemented by the following technical solutions:

[0005] A preparation method of wolfberry raw pulp, comprising the following steps:

[0006] Step one: raw material acceptance: the fresh fruit is accepted, passes through the raw material elevator, enters the air separation and removal, and then enters the conveying line. The wolfberry fresh fruit passes through the elevator, is manually selected on the conveying line, and then is conveyed to the bubble cleaning tank;

[0007] Step two: primary bubble float cleaning and sterilization: using tap water for cleaning, passing through a bubble cleaning machine for cleaning to remove impurities in the raw material fruit;

[0008] Step three: secondary bubble cleaning and sterilization: using pure water provided by the workshop pure water system for washing, passing through a two-bubble cleaning machine for cleaning, and the circulating water of the two-bubble cleaning machine is configured with a filtering system;

[0009] Step four: vibration dewatering and lifting drying: through the vibration dewatering machine and the air blower, the water on the surface of the fresh fruit is dewatered, the pure water introduced into the production line is reduced, the soluble solid content of the raw pulp is avoided to be reduced, and the quality of the raw juice is affected;

[0010] Step five: hammer crushing: the wolfberry dewatered and dried by vibration is subjected to a crushing process;

[0011] Step six: double channel beating: using high-speed double channel beating machine to remove the seed coat, carry out solid-liquid separation, and refine the product to make it small and uniform. The wolfberry raw pulp enters the buffer tank;

[0012] Step seven: colloid mill: the pulp passes through the colloid mill, which can make the large particles in the wolfberry juice smaller. After passing through the colloid mill, the raw pulp fruit particle size is less than 0.3mm. The material after the colloid mill enters the buffer tank;

[0013] Step eight: high-pressure homogenization: using high-pressure homogenizer for efficient dispersion and homogenization, making the wolfberry fruit particle size smaller, uniform and stable. After passing through the homogenizer, the fruit particle size in the wolfberry juice is ≤40um;

[0014] Step nine: preheating: after high-pressure homogenization, it needs to be preheated to 65℃±1;

[0015] Step ten: double-effect vacuum concentration: if the soluble solids of wolfberry raw pulp are >15%, then no double-effect vacuum concentration is needed. If the soluble solids of wolfberry raw pulp are ≤15%, then it enters the double-effect vacuum concentration system to reach the required sugar content;

[0016] Step eleven: vacuum degassing: using online degassing method, the purpose of degassing is to remove the gas in the juice by vacuum pumping to reduce the amount of foam generated during the concentration and sterilization process;

[0017] Step twelve: double-jacket sterilization: the microbial indicators of the sterilized wolfberry raw juice, clear juice and concentrated liquid meet the requirements;

[0018] Step thirteen: filling: aseptic filling, packaging specification 200kg aseptic bag; the product after filling reaches the commercial aseptic effect;

[0019] Step fourteen: CIP cleaning: after production, the process pipeline, crushing and beating system, homogenization, storage tank, sterilization system and filling system need to be automatically cleaned and sterilized by CIP to make the surface in contact with food clean, sanitary and without scaling.

[0020] The preparation method of wolfberry raw pulp as described above, in step two, the first bubble cleaning machine uses 30-60mg / L chlorine dioxide solution to soak the wolfberry for 10 minutes, and the cleaning time is 5-10 minutes. The first bubble cleaning machine is 4.5m long, and the cleaning lifting conveyor belt has a fruit sticking rate of ≤1%.

[0021] The preparation method of wolfberry raw pulp as described above, in step three, ozone is added to the cleaning tank of the second bubble cleaning machine for real-time ozone sterilization. The effective ozone concentration in the cleaning tank is ≥0.4mg / L, and the cleaning time is 3-5 minutes. The second bubble cleaning machine is 4.5m long, and the cleaning lifting conveyor belt has a fruit sticking rate of ≤1%.

[0022] The preparation method of the wolfberry original pulp as described above, the buffer tank of the crusher is directly placed below the crusher in the step five, the crushed material directly falls into the buffer groove, the lower end is equipped with a connecting flange with a thickness of ≥8mm, and a crushing hopper is added to the upper part and directly connected with the crusher, the particle size of the crushed fruit pulp is uniform, and the diameter of the screen mesh of the crusher is 2-4mm.

[0023] The preparation method of the wolfberry original pulp as described above, the first screen mesh of the high-speed double-channel pulper has a diameter of 1.2mm, the second screen mesh has a diameter of 0.8mm, the high-speed double-channel pulper can realize CIP automatic cleaning, the particle size of the pulp juice and fruit pulp after the double-channel pulper is 0.8mm, the pulp yield of the wolfberry fresh fruit product is more than 80%, the wolfberry seeds are separated, dried, and stored, and the wolfberry peel is dried and used as feed.

[0024] The preparation method of the wolfberry original pulp as described above, the sugar content of the wolfberry juice is measured after pulping in the step six.

[0025] The preparation method of the wolfberry original pulp as described above, the discharge temperature of the double-effect vacuum concentration system is 48±2℃ in the step ten, and an online sugar content meter is arranged to automatically control the discharge sugar content.

[0026] The preparation method of the wolfberry original pulp as described above, the sugar content in the step ten is required to be ≥18%.

[0027] The preparation method of the wolfberry original pulp as described above, the material inlet temperature is 30-50℃, the sterilization temperature is 127℃, and the sterilization time is 15S in the step twelve.

[0028] The preparation method of the wolfberry original pulp as described above, the CIP system can query alarm records and operation records, can monitor temperature, flow, time, real-time curve and historical curve, record storage "cleaning", "waiting", "stop" state can be distinguished, and performance report is formed, the inlet and outlet distributors are correctly connected, the water distributor is checked frequently to prevent blockage, the pipeline and valve are checked to be correct, then the centrifugal pump is started to clean, when the acid and alkali are used for cleaning, after cleaning, the backflow pump is opened, the acid and alkali flow into the acid tank and the alkali tank respectively, and finally the water is washed, after cleaning, the test paper is tested to be neutral.

[0029] The present application has the advantages that: the present application optimizes the cleaning and sterilization process, adopts hierarchical bubble cleaning of tap water and purified water, and combines double sterilization of chlorine dioxide and ozone, effectively removes impurities and improves the sterilization effect, and at the same time, a filtering system is configured to ensure the cleanliness of the cleaning water; in the draining link, vibration draining and air drying are combined to reduce the introduction of water to maintain the soluble solid content of the original pulp; the crushing and beating process adopts hammer crushing combined with double-beating machine, cooperates with screens with different aperture to realize seed skin separation and particle refinement, and colloid mill and high-pressure homogenization further control the fruit flesh particle size below 40 um to improve the fineness of the original pulp; the double-effect vacuum concentration system flexibly regulates and controls the concentration process according to the soluble solid content, and the online sugarimeter is matched to ensure the product sugar stability; the vacuum degassing link effectively reduces the generation of foam, and the double-jacket sterilization strictly controls the temperature and time to ensure the microbial indicators, solves the problems of small particles and unknown substances in the wolfberry original pulp, and improves the fineness of the wolfberry original pulp, finally realizes the whole-process quality control of the wolfberry original pulp from raw material treatment to finished product packaging through the sterile filling and CIP automatic cleaning system, not only retains the nutritional ingredients of wolfberry, but also significantly improves the sensory quality of the product, and meets the standardization requirements of industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0031] Figure 1 is one of the wolfberry original pulp schematic diagrams prepared by the present application;

[0032] Figure 2 is the second wolfberry original pulp schematic diagram prepared by the present application;

[0033] Figure 3 is one of the wolfberry original pulp detection report schematic diagrams prepared by the present application;

[0034] Figure 4 is the second wolfberry original pulp detection report schematic diagram prepared by the present application;

[0035] Figure 5 is the third wolfberry original pulp detection report schematic diagram prepared by the present application;

[0036] Figure 6 is the fourth wolfberry original pulp detection report schematic diagram prepared by the present application;

[0037] Figure 7 is the fifth wolfberry original pulp detection report schematic diagram prepared by the present application;

[0038] Figure 8 is the sixth detection report schematic diagram of the wolfberry raw pulp prepared by the embodiment of the present application;

[0039] Figure 9 is the seventh detection report schematic diagram of the wolfberry raw pulp prepared by the embodiment of the present application;

[0040] Figure 10 is the eighth detection report schematic diagram of the wolfberry raw pulp prepared by the embodiment of the present application. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0042] EMBODIMENT

[0043] A preparation method of wolfberry raw pulp, comprising the following steps:

[0044] Step one: raw material acceptance: the fresh fruit is accepted, passes through the raw material elevator, enters the conveying line after the wind selection and impurity removal, and the wolfberry fresh fruit is manually selected on the conveying line after passing through the elevator and then conveyed to the bubbling cleaning tank;

[0045] Step two: primary bubbling floating cleaning and sterilization: using tap water for cleaning, removing the impurities (including mud, adhering matter and fruit leaves) in the raw material fruit after passing through a bubbling cleaning machine;

[0046] Step three: secondary bubbling cleaning and sterilization: using the pure water provided by the workshop pure water system for washing, passing through a two-bubbling cleaning machine, and the circulating water of the two-bubbling cleaning machine is configured with a filtering system;

[0047] Step four: vibration dewatering, lifting and blowing dry: the water on the surface of the fresh fruit is dewatered by the vibration dewatering machine in cooperation with the air blower, the pure water introduced into the production line is reduced, the soluble solid content of the raw pulp is avoided to be reduced, and the quality of the raw juice is affected; wherein the power of the elevator is 2.2kW variable frequency; the power of the air blower is 0.55kW, and the number is 6;

[0048] Step five: hammer crushing: the wolfberry after vibration dewatering and blowing dry enters the crushing process (the fresh fruit directly enters the crushing process, and the frozen fruit enters the crushing process after rehydration and thawing operation); a 2T / H crushing system is adopted: the power of the screw pump is 2.2kW-heavy load frequency converter; the power of the crusher (500L) is 4kW;

[0049] Step six: double channel beating: using high-speed double channel beating machine to remove the seed coat, carry out solid-liquid separation, and refine the product to make the particles small and uniform. The goji berry raw pulp enters the buffer tank (1000L). The stirring power of the feeding port is 1.1kW, the power of the first channel beating machine is 7.5kW, and the power of the second channel beating machine is 7.5kW.

[0050] Step seven: colloid mill: the pulp passes through the colloid mill, which can make the size of the large particles in the goji berry juice smaller. After passing through the colloid mill, the size of the raw pulp particles is less than 0.3mm. The material after the colloid mill enters the buffer tank (1000L). The stirring power of the feeding port is 1.1kW.

[0051] Step eight: high-pressure homogenization: using high-pressure homogenizer for efficient dispersion and homogenization, making the size of the goji berry pulp smaller and uniformly and stably distributed. After passing through the homogenizer, the size of the pulp particles in the goji berry juice is ≤40um. The power of the high-pressure homogenizer is controlled to start and stop at 30kW variable frequency. The high-pressure homogenizer is connected to cooling water.

[0052] Step nine: preheating and temperature rising: after high-pressure homogenization, it needs to be preheated to 65℃±1.

[0053] Step ten: double-effect vacuum concentration: if the soluble solids of the goji berry raw pulp are >15%, double-effect vacuum concentration is not needed. If the soluble solids of the goji berry raw pulp are ≤15%, it enters the double-effect vacuum concentration system to reach the required sugar content. The double-effect vacuum concentration system (PLC touch screen control) is connected to cooling water. The power of the discharge screw pump is 1.5kW-heavy load frequency converter (one-effect circulating pump, two-effect circulating pump, vacuum pump, CIP return pump, condensate pump). The condensate tank (100L) is connected to the concentrated batch tank (2000L*2). The stirring power is 1.5kW.

[0054] Step eleven: vacuum degassing: using online degassing method, the purpose of degassing is to remove the gas in the juice by vacuum pumping to reduce the generation of a large amount of foam in the re-concentration and sterilization process.

[0055] Step twelve: double-jacket sterilization: the microbial indicators of the goji berry raw juice, clear juice and concentrated liquid after sterilization meet the requirements. The double-jacket sterilizer adopts a double-jacket sterilizer, which includes a sterilization system control cabinet (PLC touch screen control), a screw pump 2.2kW-heavy load frequency conversion, an RGZ-30-high temperature hot water pump-Olank-2.2kW, a CDMF10-6-south pump-CIP cleaning pump-2.2kW. The double-jacket sterilizer is connected to cooling water.

[0056] Step 13: Filling: sterile filling, packaging specification 200 kg sterile bag; the product after filling reaches commercial sterile effect; filling uses single-head sterile big-bag filling machine (PLC touch screen control), total power of power transmission roller is about 8 kW;

[0057] Step 14: CIP cleaning: after production, the process pipeline, crushing and pulping system, homogenization, storage tank, sterilization system and filling system need to be automatically cleaned and sterilized by CIP, so that the surface in contact with food is clean, hygienic and free of scale.

[0058] Specifically, in the step two of the embodiment, the first bubble cleaning machine is used to clean the wolfberry by soaking in 30-60 mg / L chlorine dioxide solution for 10 minutes, and the cleaning time is 5-10 minutes. The length of the first bubble cleaning machine is 4.5 m, and the cycle sticking rate of the cleaning lifting conveyor belt is ≤1%.

[0059] Specifically, in the step three of the embodiment, ozone is added to the cleaning pool of the second bubble cleaning machine for real-time ozone sterilization. The effective ozone concentration in the cleaning pool is ≥0.4 mg / L, and the cleaning time is 3-5 minutes. The length of the second bubble cleaning machine is 4.5 m, and the cycle sticking rate of the cleaning lifting conveyor belt is ≤1%.

[0060] More specifically, in the step five of the embodiment, the buffer tank of the crusher is directly placed below the crusher, and the crushed material directly falls into the buffer tank. The lower end is equipped with a connecting flange with a thickness of ≥8 mm, and the upper part is increased with a crushing hopper directly connected to the crusher. The particle size of the crushed fruit pulp is uniform, and the diameter of the crusher screen is 2-4 mm.

[0061] More specifically, in the step six of the embodiment, the first screen of the high-speed double bubble pulper has a hole diameter of 1.2 mm, and the second screen has a hole diameter of 0.8 mm. The high-speed double bubble pulper can realize CIP automatic cleaning. The particle size of the pulp juice after passing through the double bubble pulper is 0.8 mm. The pulp yield of the wolfberry fresh fruit product is more than 80%. The wolfberry seeds are separated, dried, and stored. The dried wolfberry skin is used as feed.

[0062] More specifically, in the step six of the embodiment, the sugar content of the wolfberry juice is measured after pulping.

[0063] Further, in the step ten of the embodiment, the discharge temperature of the double-effect vacuum concentration system is 48±2℃, and an online sugar content meter is provided for automatic control of the discharge sugar content.

[0064] More further, in the step ten of the embodiment, the sugar content is required to be ≥18%.

[0065] More further, in the step twelve of the embodiment, the material inlet temperature is 30-50℃, the sterilization temperature is 127℃, and the sterilization time is 15S.

[0066] Further, the CIP system in step fourteen can query alarm records and operation records, monitor temperature, flow, time, real-time curves and historical curves, record and store "cleaning", "waiting", "stopping" states, distinguish and form performance reports, correctly connect the inlet and outlet distributors, frequently check the water feeders to prevent blockage, check the pipeline and valves for no errors, and then start the centrifugal pump for cleaning.

[0067] The prepared wolfberry original pulp product of the embodiment of the present application is as shown in Figure 1 and Figure 2 The detection report of the prepared wolfberry original pulp product of the embodiment of the present application is as shown in Figures 3-10 It can be known from Figures 3-10 that the prepared product of the present application meets the safety of drinks, and the solubility of the prepared wolfberry original pulp of the present application is higher than 19%, and there is no impurity in the drink, so that the present application can prepare high-quality wolfberry original pulp products.

[0068] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing wolfberry juice, characterized in that: Includes the following steps: Step 1: Raw material acceptance: Fresh fruits are accepted. After passing through the raw material elevator, they enter the air separation to remove impurities and then enter the conveyor line. After passing through the elevator, the fresh goji berries are initially sorted by hand on the conveyor line and then transported to the bubble washing tank. Step 2: Primary Bubble Washing and Sterilization: Use tap water for washing, passing through a bubble washing machine to remove impurities from the raw fruit; Step 3: Secondary bubble cleaning and sterilization: Rinse with pure water provided by the workshop's pure water system, and then clean with a secondary bubble cleaning machine. The circulating water in the secondary bubble cleaning machine is equipped with a filtration system. Step 4: Vibration Draining and Blowing: The vibration draining machine, in conjunction with a blower, drains the surface moisture of the fresh fruit, reducing the amount of pure water introduced into the production line and avoiding a decrease in the soluble solids content of the pulp, which would affect the quality of the juice. Step 5: Hammer crushing: The vibrating, drained, and dried goji berries enter the crushing process; Step Six: Double-stage pulping: A high-speed double-stage pulping machine is used to remove the seed husks and perform solid-liquid separation. At the same time, the product is refined to make the goji berry pulp into small and uniform particles before entering the buffer tank. Step 7: Colloid mill: The slurry is ground by colloid mill, which can reduce the size of large particles of pulp in the goji berry juice. After passing through the colloid mill, the original berry pulp particle size reaches less than 0.3mm. The material after passing through the colloid mill enters the buffer tank. Step 8: High-pressure homogenization: High-pressure homogenizer is used for efficient dispersion and homogenization, which reduces the particle size of goji berry pulp, making it more uniform and stable. After homogenization, the pulp particles in the goji berry juice are ≤40um. Step 9: Preheating: After high-pressure homogenization, preheating to 65℃±1 is required; Step 10: Double-effect vacuum concentration: If the soluble solids content of the goji berry pulp is >15%, then double-effect vacuum concentration is not required. If the soluble solids content of the goji berry pulp is ≤15%, then it enters the double-effect vacuum concentration system to reach the required sugar content. Step 11: Vacuum degassing: Online degassing is used. The purpose of degassing is to remove gas from the juice by vacuuming to reduce the amount of foam generated during the reconcentration and sterilization process. Step 12: Tube sterilization: The microbial indicators of the sterilized wolfberry juice, clear juice and concentrated liquid meet the requirements; Step 13: Filling: Aseptic filling, packaging specification 200kg aseptic bags; the filled product achieves commercial sterility; Step Fourteen: CIP Cleaning: After production is completed, the process pipelines, crushing and pulping system, homogenizing, storage tanks, sterilization system, and filling system need to be automatically cleaned and sterilized by CIP to ensure that the surfaces that come into contact with food are clean, hygienic, and free of scale.

2. The method for preparing wolfberry juice according to claim 1, characterized in that: In step two, the goji berries are soaked in a 30-60 mg / L chlorine dioxide solution for 10 minutes using a bubbling cleaning machine. The cleaning time is 5-10 minutes. The bubbling cleaning machine is 4.5 m long, and the fruit sticking rate of the cleaning and lifting conveyor belt circulation is ≤1%.

3. The method for preparing wolfberry juice according to claim 1, characterized in that: In step three, ozone is added to the cleaning tank of the two-stage bubbling cleaning machine for real-time ozone sterilization. The effective ozone concentration in the cleaning tank is ≥0.4mg / L, the cleaning time is 3-5min, the two-stage bubbling cleaning machine is 4.5m long, and the fruit sticking rate of the cleaning lifting conveyor belt is ≤1%.

4. The method for preparing wolfberry juice according to claim 1, characterized in that: In step five, the crusher buffer tank is placed directly below the crusher, and the crushed material falls directly into the buffer tank. The lower end is equipped with a connecting flange with a thickness of ≥8mm, and a crushing hopper is added at the top, which is directly connected to the crusher. The crushed pulp has a uniform particle size, and the crusher screen diameter is 2-4mm.

5. The method for preparing wolfberry juice according to claim 1, characterized in that: In step six, the high-speed double-stage pulper has a first-stage screen with a mesh size of 1.2 mm and a second-stage screen with a mesh size of 0.8 mm. The high-speed double-stage pulper can achieve CIP automatic cleaning. After passing through the double-stage pulper, the pulp and fruit pulp particles have a size of 0.8 mm. The pulp yield of fresh wolfberry products reaches more than 80%. After separation and drying, the wolfberry seeds are stored, and the wolfberry peels are dried and used as feed.

6. The method for preparing wolfberry juice according to claim 1, characterized in that: In step six, the sugar content of the goji berry juice is measured after pulping.

7. The method for preparing wolfberry juice according to claim 1, characterized in that: In step ten, the discharge temperature of the double-effect vacuum concentration system is 48±2℃, and it is equipped with an online saccharimeter to automatically control the discharge saccharimeter.

8. The method for preparing wolfberry juice according to claim 1, characterized in that: The sugar content in step ten must be ≥18%.

9. The method for preparing wolfberry juice according to claim 1, characterized in that: The material inlet temperature in step twelve is 30-50℃; the sterilization temperature is 127℃; and the sterilization time is 15 seconds.

10. The method for preparing wolfberry juice according to claim 1, characterized in that: In step fourteen, the CIP system can query alarm records and operation records, monitor temperature, flow rate, time, real-time curves and historical curves, and store "cleaning", "waiting" and "stop" states that can be distinguished and generate performance reports. The inlet and outlet distributors should be connected correctly, and the water supply device should be checked frequently to prevent blockage. The centrifugal pump can only be started for cleaning after the pipes and valves are checked to be correct. When cleaning with acid and alkali, after cleaning, the return pump should be turned on so that the acid and alkali flow into the acid tank and alkali tank respectively. Finally, rinse with clean water. After cleaning, the solution should be tested with test paper and found to be neutral.

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