Preparation method of red raspberry fresh fruit fermented jam

Abstract

The present invention discloses a method for preparing a fermented red raspberry fruit jam, which specifically comprises the following steps: (1) collecting fresh red raspberry fruits, soaking, rinsing, and draining; (2) beating into a homogenate, boiling, and sterilizing to obtain a raw red raspberry fruit pulp for later use; (3) mixing Lactobacillus plantarum, Lactobacillus paracasei, and Lactobacillus acidophilus; (4) adding water to dilute according to a proportion, and then inoculating and fermenting; (5) adding white sugar, citric acid, vitamin C, and xanthan gum to mix, mix, and stir to obtain the jam. The fermented red raspberry fruit jam of the present invention is sweet and sour and has a smoother taste. The bacteria in the fermentation process have a certain immunomodulatory effect, an inhibitory effect on pathogenic bacteria, and significant antioxidant and blood lipid-lowering effects. Regular consumption of the fermented red raspberry fruit jam has the effects of preventing cardiovascular diseases, maintaining the balance of intestinal flora, promoting nutrient absorption, alleviating lactose intolerance, and inhibiting the formation of tumor cells.

Description

Technical Field

[0001] The invention relates to the technical field of food fermentation, and more particularly to a method for preparing red raspberry fresh fruit fermented jam. Background Art

[0002] Red raspberries are bright, tender, and juicy, rich in color, anthocyanins, ellagic acid, superoxide dismutase, flavonoids, and other bioactive substances, as well as essential amino acids. Furthermore, red raspberries possess numerous benefits and functions, including antioxidant, anticancer, antibacterial, anti-inflammatory, lipid-lowering, and immune-enhancing properties. They are effective in preventing and treating a variety of modern diseases, possessing high nutritional and health benefits and economic value. They are widely recognized by consumers worldwide and are known as the "King of Fruits" and "Golden Fruit" in the international market. While red raspberries are nutritious and offer excellent health benefits, they are also susceptible to oxidation, are extremely fragile in storage, and are unsuitable for long-distance transportation.

[0003] Jam, also known as fruit preserve, is a gel-like substance made by mixing fruit, sugar, and an acidifier and cooking it at temperatures exceeding 100°C. Making jam is a method of preserving fruit for a long period of time. However, methods for fermenting fresh red raspberry jam have not been reported, and its antioxidant and lipid-lowering effects have not been verified.

[0004] Therefore, how to prepare a red raspberry fresh fruit fermented jam is a problem that those skilled in the art need to solve urgently. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a method for preparing red raspberry fresh fruit fermented jam to overcome the deficiencies in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing red raspberry fresh fruit fermented jam specifically comprises the following steps:

[0008] (1) Collect fresh red raspberry fruits that are mature, uniform in size, free of mechanical damage and pests and diseases, and dark red in color, soak them in water to remove branches, leaves and soil, rinse them repeatedly, remove them and drain them to obtain red raspberry fruits;

[0009] (2) Blend the red raspberry fruits into a homogenate, boil, and sterilize to obtain the red raspberry fruit pulp for later use;

[0010] (3) mixing Lactobacillus plantarum, Lactobacillus paracasei and Lactobacillus acidophilus to obtain a mixed strain;

[0011] (4) First, dilute the mixed strain with water, and then inoculate it into the red raspberry pulp for fermentation to obtain red raspberry fermentation liquid;

[0012] (5) Add white sugar, citric acid, vitamin C and xanthan gum to the red raspberry fermentation liquid, mix and stir to obtain red raspberry fresh fruit fermented jam.

[0013] Furthermore, in the above step (2), the mixture is boiled until it becomes slightly viscous.

[0014] Furthermore, in the above step (2), the sterilization temperature is 95°C and the time is 20 minutes.

[0015] Furthermore, in the above step (3), the mass ratio of Lactobacillus plantarum, Lactobacillus paracasei and Lactobacillus acidophilus is 2:1:1.

[0016] The above-mentioned further beneficial effect is that the number of viable bacteria of Lactobacillus plantarum is relatively high, and it can produce a large amount of acid. Its main function is to maintain intestinal health, and it is also beneficial to the treatment of other diseases related to the large and small intestines and colon; Lactobacillus paracasei has good acid and bile resistance, can lower plasma cholesterol, enhance the host's nonspecific resistance to microbial pathogens, accelerate the clearance of pathogens in the intestine, can treat intestinal flora disorders and enhance intestinal permeability, thereby preventing food allergies and acute diarrhea; Lactobacillus acidophilus can adjust the balance of intestinal flora, inhibit the proliferation of harmful intestinal microorganisms, and is beneficial to the digestive organs.

[0017] Furthermore, in the above step (4), the mass ratio of the mixed bacteria to water is 1:250.

[0018] Furthermore, in the above step (4), the ratio of the mixed strain to the red raspberry pulp is 0.2U:1L.

[0019] Furthermore, in the above step (4), the fermentation temperature is 39°C and the fermentation time is 80 hours.

[0020] Furthermore, in the above step (5), based on the mass of the red raspberry fermentation liquid being 100%, the masses of white sugar, citric acid, vitamin C and xanthan gum are 17%, 1%, 0.3% and 0.3% respectively.

[0021] The above-mentioned further beneficial effect is that white sugar and citric acid are food additives, which can be appropriately added to increase the palatability of jam and make it acceptable to the public; vitamin C is a color preservative, which ensures that the jam will not turn brown during storage and thus affect the color; xanthan gum is a thickener, which can make the jam more viscous and have a richer taste without affecting human health.

[0022] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. The fermented red raspberry jam of the present invention is sweet and sour, with a smoother mouthfeel. The bacterial strains in the fermentation process have a certain immunomodulatory effect, an inhibitory effect on pathogenic bacteria, and a significant antioxidant and lipid-lowering effect. Regular consumption has the effects of preventing cardiovascular disease, maintaining intestinal flora balance, promoting nutrient absorption, alleviating lactose intolerance, and inhibiting the formation of tumor cells. Moreover, the present invention alleviates to a large extent the limitations of red raspberry fresh fruit, which is rich in nutrients but easily oxidized, and extremely intolerant to storage and long-distance transportation. It not only improves the flavor, but also helps accumulate plant polyphenols in the fermented red raspberry fresh fruit jam, thereby helping to exert antioxidant, antibacterial, anti-inflammatory, anticancer, beauty, anti-aging and other effects, and will significantly improve the economic and social benefits of the regional red raspberry industry.

[0024] 2. Compared with the original red raspberry pulp, the DPPH, ABTS and FRAP of the red raspberry fresh fruit fermented jam increased by 31.15%, 9.21% and 1.16 μmol / mL respectively, indicating that the antioxidant function indicators of the red raspberry fresh fruit fermented jam were significantly improved.

[0025] 3. Compared with the original red raspberry pulp, the optimal addition amount of red raspberry fresh fruit fermented jam was reduced by 20%; at the optimal combination, the binding rates of sodium taurocholate and sodium glycocholate in the red raspberry fresh fruit fermented jam increased by 11.61% and 5.74% respectively, indicating that the lipid-lowering function of the red raspberry fresh fruit fermented jam was significantly improved.

[0026] 4. The soluble solids of the fermented red raspberry fresh fruit jam of the present invention are ≥25 mg / kg, as specified in GB / T 10786; the total arsenic is ≤0.5 mg / kg, as specified in GB5009.11; and the lead is ≤1.0 mg / kg, as specified in GB / 5009.12.

[0027] 5. The microbial indicators of the fermented red raspberry fresh fruit jam of the present invention meet the requirements for commercial sterility of jam food, the total colony count (cfu / mL) is ≤50, the coliform group (cfu / mL) is ≤3, pathogenic bacteria are not detected, and the food additives meet the hygiene standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The effect of fermentation time on the number of viable bacteria in red raspberry fresh fruit fermented jam;

[0029] Figure 2 The study aimed to investigate the effects of fermentation time on the total amino acids and sensory scores of fermented red raspberry jam.

[0030] Figure 3 The study is about the effect of fermentation temperature on the number of viable bacteria in fermented red raspberry jam.

[0031] Figure 4To study the effect of fermentation temperature on the total amino acids and sensory scores of red raspberry fresh fruit fermented jam;

[0032] Figure 5 The effect of sugar addition on the number of viable bacteria in fermented red raspberry jam;

[0033] Figure 6 The effect of sugar addition on the total amino acids and sensory scores of red raspberry fresh fruit fermented jam;

[0034] Figure 7 is the standard curve of sodium glycocholate solution;

[0035] Figure 8 is the standard curve of sodium taurocholate solution;

[0036] Figure 9 To study the effect of different addition amounts on the bile salt binding rate of red raspberry puree and red raspberry fresh fruit fermented jam;

[0037] Figure 10 The study aimed to investigate the effects of different shaking times on the bile salt binding rate of red raspberry puree and red raspberry fresh fermented jam.

[0038] Figure 11 This is a physical picture of the red raspberry raw fruit pulp in step (2) of Example 1;

[0039] Figure 12 This is a photo of the fermented red raspberry jam in step (5) of Example 1. DETAILED DESCRIPTION

[0040] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention. Example

[0041] The preparation method of red raspberry fresh fruit fermented jam specifically comprises the following steps:

[0042] (1) Collect fresh red raspberry fruits that are mature, uniform in size, free of mechanical damage and pests and diseases, and dark red in color, soak them in water to remove branches, leaves and soil, rinse them repeatedly, remove them and drain them to obtain red raspberry fruits;

[0043] (2) First, put the red raspberry fruit into a juicer and beat it into a homogenous paste. Then put it into a pot and simmer it over low heat until it is slightly viscous. Then put it into a 95℃ water bath and sterilize it for 20 minutes to obtain the red raspberry raw fruit pulp (such as Figure 11 As shown), spare;

[0044] (3) mixing Lactobacillus plantarum, Lactobacillus paracasei, and Lactobacillus acidophilus at a mass ratio of 2:1:1 to obtain a mixed strain;

[0045] (4) First, the mixed strains were diluted with ultrapure water at a mass ratio of 1:250, and then inoculated into the red raspberry pulp at a dosage ratio of 0.2U:1L, and fermented at 39°C for 80h to obtain red raspberry fermentation liquid;

[0046] (5) Taking the mass of the red raspberry fermentation liquid as 100%, add 17% white sugar, 1% citric acid, 0.3% vitamin C and 0.3% xanthan gum to the red raspberry fermentation liquid, mix and stir to obtain the red raspberry fresh fruit fermentation jam (such as Figure 12 shown).

[0047] 1. Optimization experiment on fermentation parameters of red raspberry fresh fruit fermented jam

[0048] This study used the number of viable bacteria and sensory scores in red raspberry fresh fruit fermented jam as indicators to optimize the fermentation parameters of red raspberry fresh fruit fermented jam, providing scientific data and theoretical reference for the research of red raspberry fresh fruit fermented jam.

[0049] 1 Test materials

[0050] 1.1 Purchase and storage of experimental strains

[0051] The freeze-dried powders of three mixed strains of Lactobacillus plantarum, Lactobacillus paracasei, and Lactobacillus acidophilus were purchased from Weikang Probiotics (Suzhou) Co., Ltd. and stored in the Fruit and Vegetable Fermentation Engineering Laboratory of the School of Food Science and Engineering, Shihezi University.

[0052] 1.2 Test sample collection and main instruments

[0053] Fresh red raspberries that were mature, uniform in size, free of mechanical damage and pests and diseases, and dark red in color were collected from the planting base in Majiazhuang Village, Manas County, Changji Hui Autonomous Prefecture, Xinjiang Uygur Autonomous Region, and stored in a -20℃ refrigerator for future use.

[0054] The main instruments used in the experiment are shown in Table 1.

[0055] Table 1 Main instruments

[0056]

[0057] 1.3 Main reagents used in the experiment

[0058] The main reagents used in the test include NYS solid culture medium, MRS agar, food-grade pectinase, food-grade citric acid, agar strips / carrageenan, food-grade sodium chloride, glacial acetic acid, food-grade vitamin C, food xanthan gum, sodium hydroxide and phenolphthalein indicator.

[0059] 1.4 Process flow of fermentation steps for red raspberry fresh fruit fermented jam

[0060] Red raspberry → screening → cleaning → making raspberry juice with a juicer → boiling → sterilization (95° C., 20 min) → inoculation → fermentation → blending → finished product → storage at -4° C. For details, see Example 1.

[0061] 1.5 Method for determining viable cell count

[0062] In order to determine the number of viable lactobacilli, the plate count method was used to determine the number of viable lactobacilli in the fermentation broth. The determination steps are as follows:

[0063] (1) Storage of fermentation broth: Store in a refrigerator at -4°C;

[0064] (2) MRS agar was added to ultrapure water at a mass ratio of 1:15 and stirred. The mixture was placed in an autoclave along with the glass culture dish and sterilized at 121°C for 30 min. When the autoclave cooled to 64°C and the exhaust was complete, the lid was opened and the agar was taken out.

[0065] (3) Cool the culture medium to about 50°C (not too hot to touch), place it in a sterile inoculation box that has been sterilized for 15 minutes in advance, put on gloves to disinfect the table and hands, and pour the culture medium under sterile conditions. Shake the culture medium well before pouring it into the plate to prevent precipitation at the bottom of the bottle. At the same time, prevent the generation of a large number of bubbles when shaking. After pouring the plate, wait for the agar to solidify and no liquid to flow before inoculating;

[0066] (4) Take 1 mL of fermentation liquid and place it in a sterile test tube containing 9 mL of normal saline. Mix it with a vortex oscillator, and take 1 mL of the liquid in this test tube and add it to the next sterile test tube containing 9 mL of normal saline. Use this method to perform serial dilutions, and select test tubes with 4-fold, 5-fold, 6-fold, 7-fold, 8-fold, 9-fold, 10-fold and 11-fold dilutions as the dilution gradient (in this study, the fermentation liquid of red raspberry fruit was more suitable for a 6-8-fold dilution, with a viable bacterial count of 30-300 cfu and a sensory score greater than 88 points);

[0067] (5) Open the ultraviolet sterilization of the sterile inoculation box in advance and light the alcohol lamp to disinfect and sterilize the inoculation loop;

[0068] (6) Add 100 μL of fermentation liquid to the surface of the plate, evenly spread the agar surface with an inoculating loop and mark it;

[0069] (7) Place the inoculated culture dish in a 37°C incubator for 48 hours, then count the plates with colony counts between 30 and 300, using the counting unit of cfu / mL (Note: Not all colonies grown on selective culture medium are effective bacteria; the selectivity of the culture medium is relative).

[0070] 1.6 Sensory Evaluation of Red Raspberry Fresh Fruit Fermented Jam

[0071] A total of 20 trained teachers and students (aged 22-58), 10 males and 10 females, evaluated the color, taste, aroma, and clarity of fermented red raspberry fresh fruit jam. The evaluation results were based on a 100-point system, and the average value was taken as the final sensory score. The specific evaluation criteria are shown in Table 2.

[0072] Table 2 Sensory scoring criteria for red raspberry fresh fermented jam

[0073]

[0074] 1.7 Fermentation single factor experiment

[0075] Taking the viable bacteria count and sensory score of red raspberry fresh fruit fermented jam as indicators, single factor experiments were conducted on initial fermentation time, fermentation temperature and sugar addition amount.

[0076] The factors were set as follows: the initial fermentation temperature was set at 37°C, and the fermentation times were 56, 64, 72, and 80 hours, respectively, to determine the optimal fermentation time for the single-factor fermentation. After determining the optimal time, the temperatures were set to 37, 39, 41, and 43°C, respectively, to determine the optimal temperature for the single-factor fermentation. After determining the optimal time and temperature, 11%, 14%, 17%, and 20% white sugar were added, respectively, to determine the optimal sugar addition level for the single-factor fermentation.

[0077] 1.8 Orthogonal Experimental Design for Fermentation

[0078] On the basis of the above single factor test, a three-factor three-level orthogonal analysis test was conducted. The test was carried out according to L9 (3 3 ) The orthogonal experimental factors and levels are shown in Table 3.

[0079] Table 3 Orthogonal experimental factor level design

[0080]

[0081] 1.9 Data Processing

[0082] The relevant parameters were measured in triplicate. Graphs were constructed using Origin 2021 and the R software package. Analysis of variance was performed using SPSS 26.0.

[0083] 2 Results and Analysis

[0084] 2.1 Single-factor experiment

[0085] (1) Effects of fermentation time on the number of viable bacteria, total amino acids and sensory scores of red raspberry fresh fruit fermented jam

[0086] Fermentation time affects the growth of Lactobacillus and the types and contents of its metabolites. Choosing the right fermentation time is crucial for Lactobacillus fermentation.

[0087] Depend on Figure 1 As can be seen, the viable cell count initially increased and then decreased slightly with prolonged fermentation time. At 72 hours, the viable cell count reached its maximum, after which the trend leveled off and slightly decreased. This phenomenon may be due to the limited nutrients in the fermented red raspberry jam, which nearly saturated the available nutrients for Lactobacillus. Furthermore, as the Lactobacillus grew, the pH in the fermented red raspberry jam gradually decreased, and an excessively low pH inhibited the growth and survival of Lactobacillus.

[0088] Depend on Figure 2 As can be seen, the sensory score of the fermented red raspberry jam increased and then decreased with increasing fermentation time, reaching a peak of 87.33 points at 72 hours of fermentation. Total amino acids continued to increase, but the rate of increase gradually slowed, reaching a maximum of 9.13 mg / g at 80 hours. At 56 hours of fermentation, due to the short fermentation time, the bacterial flora was not fully fermented, the flavor was not formed, the taste was poor, and the total amino acid content was also low. From 64 to 72 hours, the bacterial flora had a longer period of fermentation, and the sensory score and total amino acid content increased. At 80 hours of fermentation, this may be due to the late fermentation, the concentration of jam reactants and sugar content decreased, the metabolism of lactobacilli slowed down, and the rate of increase of total amino acids slowed down. This may be due to the consumption of organic acids in the system by lactobacilli, resulting in the conversion of malic acid. At the same time, due to the long fermentation time and excessive fermentation, other metabolites were produced, resulting in a poor taste and a decreased sensory score.

[0089] Taking all the above factors into consideration, the optimal fermentation time was 72 h. Therefore, this study selected a fermentation time of 64-80 h for further optimization.

[0090] (2) Effects of fermentation temperature on viable bacterial count, total amino acids and sensory scores of red raspberry fresh fruit fermented jam

[0091] Depend on Figure 3As can be seen, as the fermentation temperature increases, the viable cell count first increases and then decreases. The viable cell count reaches its maximum at 39°C and begins to decrease as the temperature continues to rise. This may be because Lactobacillus grows slowly at lower temperatures, resulting in a lower viable cell count. As the temperature rises, Lactobacillus reaches a temperature suitable for growth, at which point the viable cell count is highest. However, due to the limited heat tolerance of the strain, the viable cell count begins to decrease as the temperature continues to rise. Another possible reason is that when the temperature is too high, Lactobacillus produces acid too quickly, and the excessive acidity inhibits the growth of Lactobacillus, resulting in a decrease in the viable cell count.

[0092] Depend on Figure 4 As can be seen, the sensory score of fermented red raspberry jam did not change much with increasing fermentation temperature, fluctuating slightly around a good level (85 points). Total amino acids initially increased and then decreased, reaching a maximum of 8.66 mg / g at 39°C. While fermentation temperature had little effect on sensory scores, it had a more significant impact on total amino acid content. At 37°C, the fermentation time was below the optimal level for the bacterial flora, resulting in a slower reaction rate and lower total amino acid content. At 39°C, the fermentation rate increased, allowing for a more complete reaction with the jam, resulting in a faster increase in total amino acid content per unit time and an increase in total amino acid content. At 41-43°C, increasing temperature inhibited the activity of fermentation-related enzymes, leading to a gradual slowing of the reaction rate and a decrease in total amino acid content.

[0093] Based on the above reasons, the optimal fermentation temperature level was selected as 39°C. Therefore, this study selected the fermentation temperature of 37-41°C for further optimization.

[0094] (3) Effects of sugar addition on the number of viable bacteria, total amino acids, and sensory scores of red raspberry fresh fruit fermented jam

[0095] Depend on Figure 5 As can be seen, as the amount of sugar added increases, the number of viable bacteria increases first and then decreases. The viable bacteria count reaches its maximum value at a sugar addition of 17%, and then begins to decline as the sugar addition continues to increase. This may be because when the sugar addition is low, the energy supply is low, and the Lactobacillus grows slowly, resulting in a low viable bacteria count. As the sugar addition increases, the Lactobacillus reaches the conditions suitable for growth, and the viable bacteria count is the highest at this time. However, since the bacteria have a certain limit to resisting the environmental osmotic pressure, the environmental osmotic pressure increases with the increase in sugar addition, inhibiting the growth of Lactobacillus and causing a decrease in the viable bacteria count.

[0096] Depend on Figure 6As can be seen, sensory scores increased with increasing sugar addition, while total amino acid content initially increased and then decreased. Total amino acid content peaked at 8.82 mg / g at a sugar addition of 17%. At sugar additions of 11% to 17%, both the sensory scores and total amino acid content of fermented red raspberry jam increased. At 20% sugar addition, sensory scores continued to rise, while total amino acid content decreased. This may be because the higher sugar content increased osmotic pressure, inhibiting bacterial activity and leading to a decrease in total amino acid content.

[0097] Based on the above reasons, the optimal sugar addition level was selected as 17%. Therefore, this study selected a sugar addition level of 14% to 20% for further optimization.

[0098] 2.2 Orthogonal experiment

[0099] The results are shown in Table 4-5.

[0100] Table 4 Results of orthogonal test of red raspberry fresh fruit fermented jam

[0101]

[0102] Table 5 Results of factor variance analysis

[0103]

[0104] Table 4 shows that, using sensory scores as the evaluation metric, the order of influence of the three factors on the fermentation of red raspberry jam follows: A > C > B, i.e., fermentation time > sugar addition > fermentation temperature. Using total amino acid content as the evaluation metric, the order of influence of the three factors on the fermentation of red raspberry jam follows: A > B > C, i.e., fermentation time > fermentation temperature > sugar addition.

[0105] Table 5 shows that fermentation time, fermentation temperature, and sugar addition significantly affected the sensory scores of the red raspberry jam fermented with this microbial community (P < 0.05). Based on sensory scores, a comprehensive analysis revealed the optimal process combination to be A3B3C2, with a fermentation time of 80 h, a fermentation temperature of 39°C, and a sugar addition of 17%.

[0106] In summary, the optimal results of the orthogonal experiment are: the optimal fermentation time is 80h, the optimal fermentation temperature is 39℃, and the optimal sugar addition amount is 17%.

[0107] 2. Antioxidant Test of Red Raspberry Fresh Fruit Fermented Jam

[0108] 1. Test samples and reagents

[0109] Samples: red raspberry puree (before fermentation) and red raspberry fresh fruit fermented jam (after fermentation) prepared in Example 1.

[0110] Reagents: See the respective indicator kits for details: total antioxidant capacity (DPPH, ABTS, FRAP), all purchased from Nominkoda (Wuhan) Biotechnology Co., Ltd.

[0111] 2 Test instruments

[0112] 3D tissue cryogenic grinding instrument (KZ-5f-3D, Sewell Biotechnology), HH-6 digital constant temperature water bath, Plande Titrette titrator (accuracy 0.01), low-temperature centrifuge (h1-16kr, Hunan Kecheng), microplate reader (spectra Max ABSplus, Molecular Beauty Valley, USA), water bath, low-temperature centrifuge, anhydrous ethanol, etc.

[0113] 3 Test methods

[0114] 3.1 DPPH method

[0115] The DPPH free radical has a single electron, exhibits strong absorption at 515 nm, and its alcohol solution appears purple. In the presence of a free radical scavenger, the absorption gradually disappears due to pairing with the single electron. The lighter the color, the lower the A value, allowing for quantitative analysis of the DPPH scavenging rate in the sample.

[0116] 3.2 ABTS method

[0117] ABTS is oxidized to green ABTS+ in the presence of appropriate oxidants. The production of ABTS+ will be inhibited in the presence of antioxidants. By measuring the absorbance of ABTS+ at 734 nm, the ABTS clearance rate in the sample can be determined and calculated.

[0118] 3.3 FRAP method

[0119] FRAP method is that in an acidic environment, antioxidants can reduce Fe 3+ -tripyridine triazine (Fe 3+ -TPTZ) produces blue Fe 2+ -TPTZ, followed by blue Fe 2+ -TPTZ, the FRAP clearance ability in the sample can be obtained.

[0120] 4 Test results

[0121] The results are shown in Table 6 (Note: "*" indicates significant differences between the indicators of red raspberry raw fruit pulp and red raspberry fresh fruit fermented jam).

[0122] Table 6 Antioxidant function indexes of red raspberry puree and red raspberry fresh fruit fermented jam

[0123]

[0124] As shown in Table 6, compared with the red raspberry raw fruit pulp, the DPPH, ABTS and FRAP of the red raspberry fresh fruit fermented jam increased by 31.15%, 9.21% and 1.16 μmol / mL, respectively.

[0125] The above experiments show that compared with red raspberry raw fruit pulp, the antioxidant function indicators of red raspberry fresh fruit fermented jam are significantly improved.

[0126] 3. Blood lipid-lowering trial of red raspberry fresh fruit fermented jam

[0127] 1. Test samples and reagents

[0128] Samples: red raspberry puree (before fermentation) and red raspberry fresh fruit fermented jam (after fermentation) prepared in Example 1.

[0129] Reagents: pepsin, trypsin, sodium glycine cholate (SGC), and sodium taurocholate (STC), all of analytical grade; as well as cholesterol, sodium chloride, hydrochloric acid, sodium hydroxide, and sulfuric acid.

[0130] 2 Test instruments

[0131] Electronic balance (accuracy 0.01g), electric constant temperature water bath, constant temperature oscillator, low-speed centrifuge, high-speed centrifuge, full-wavelength microplate reader.

[0132] 3 Test methods

[0133] Determination of the adsorption of sodium cholate by red raspberry fresh fruit fermented jam samples.

[0134] 3.1.1 Bile salt detection and standard curve drawing

[0135] 0.3 mmol / L sodium glycocholate and sodium taurocholate solutions (prepared with 0.1 mol / L phosphate buffer solution, pH = 6.3) were respectively transferred into 10 mL stoppered test tubes at 0, 0.1, 0.5, 1.0, 1.5, 2.0, and 2.5 mL. 0.1 mol / L, pH = 6.3 PBS buffer was added to 2.5 mL, and then 7.5 mL of 60% sulfuric acid solution was added. The mixture was incubated in a water bath at 70°C for 20 min, then taken out and cooled to room temperature. The reaction solution was scanned at all wavelengths to determine its maximum absorption wavelength, and standard curves of the two bile salts were drawn.

[0136] 3.1.2 In vitro bile salt binding assay

[0137] Prepare 10 mg / mL of pepsin and trypsin, respectively, in 0.1 mol / L PBS buffer, pH 6.3, and set aside. Two 150 mg portions of test sample were weighed and placed in 100 mL stoppered Erlenmeyer flasks. 1 mL of 0.01 mol / L hydrochloric acid solution and 3 mL of pepsin were added, followed by constant shaking at 37°C for 1 hour to simulate the gastric environment. Subsequently, 4 mL of trypsin was added, and the pH was adjusted to 6.3 with 0.1 mol / L sodium hydroxide solution. Digestion was continued at 37°C for 1 hour with constant shaking to simulate the intestinal environment. Subsequently, 4 mL of bile salt solution (0.3 mmol / L sodium glycocholate solution or sodium taurocholate solution, both prepared in 0.1 mol / L PBS buffer, pH 6.3) was added to each sample. After constant shaking at 37°C for 1 hour, the samples were transferred to 50 mL centrifuge tubes and centrifuged at 4000 rpm for 20 minutes. The supernatant was collected and the bile salt content was determined.

[0138] 3.1.3 Colorimetric determination of bile salt content

[0139] Transfer 2.5 mL of the supernatant collected in step 3.1.2 to a 10 mL test tube and add 7.5 mL of 60% sulfuric acid. Incubate in a 70°C water bath for 20 minutes, then in an ice bath for 5 minutes. Measure the absorbance at 387 nm. Determine the concentration of each bile salt in the sample solution using the standard curve.

[0140] The binding rate of the test sample to each bile salt is as follows.

[0141] .

[0142] 3.1.4 Effects of different addition amounts on the bile salt binding rate of red raspberry puree and red raspberry fresh fruit fermented jam

[0143] Weigh 60 mg, 90 mg, 120 mg, 150 mg, 180 mg, 210 mg, and 240 mg of red raspberry puree and red raspberry fresh fermented jam samples, respectively, and place them in 100 mL stoppered Erlenmeyer flasks. Perform the assay according to "3.1.2". After the assay is complete, collect the supernatant and assay the bile salt content in the supernatant according to "3.1.3".

[0144] 3.1.5 Effects of different shaking times on the bile salt binding rate of red raspberry puree and red raspberry fresh fruit fermented jam

[0145] Take 0.12g of red raspberry raw fruit pulp and red raspberry fresh fruit fermented jam samples respectively and place them in 6 100mL stoppered Erlenmeyer flasks. Set 6 different shaking time levels of "20min, 40min, 60min, 80min, 100min and 120min" and perform the determination according to "3.1.2". After the end, take the supernatant and determine the bile salt content in the sample supernatant according to "3.1.3".

[0146] 4 Test results

[0147] 4.1 Standard curves for sodium glycocholate solution and sodium taurocholate solution

[0148] At a wavelength of 387 nm, the standard curves of sodium glycocholate solution and sodium taurocholate solution were drawn, and the results were as follows: Figure 7-8 shown.

[0149] Depend on Figure 7 It can be seen that the standard curve of sodium glycocholate solution is y=0.5365x+0.0172, and the correlation coefficient R 2 =0.9987. Figure 8 It can be seen that the standard curve of sodium taurocholate solution is y=0.2995x+0.0067, and the correlation coefficient R 2 =0.9991. The correlation coefficient between the two equations shows that the standard curve has good linearity.

[0150] 4.2 Effects of different addition amounts and shaking times on the bile salt binding rate of red raspberry puree and red raspberry fresh fruit fermented jam

[0151] The results are as follows Figure 9-10 shown.

[0152] Depend on Figure 9 The results show that the optimal addition amount of fresh red raspberry fruit to fermented jam is 0.12g, at which the binding rates of sodium taurocholate and sodium glycocholate are 56.9% and 58.61%, respectively. The optimal addition amount of raw red raspberry fruit to puree is 0.15g, at which the binding rates of sodium taurocholate and sodium glycocholate are 48% and 60.03%, respectively.

[0153] Depend on Figure 10 The results show that the optimal adsorption time for red raspberry fresh fermented jam is 60 minutes, at which the binding rates of sodium taurocholate and sodium glycocholate are 55.09% and 65.37%, respectively. The optimal adsorption time for red raspberry raw fruit pulp is 60 minutes, at which the binding rates of sodium taurocholate and sodium glycocholate are 44.26% and 47.13%, respectively.

[0154] 5 Conclusion

[0155] The lipid-lowering effect of red raspberry fresh fruit fermented jam was evaluated. The optimal addition amount was 0.12g, the optimal adsorption time was 60min, and at the optimal combination, the binding rates of sodium taurocholate and sodium glycocholate in red raspberry fresh fruit fermented jam were 55.09% and 65.37%, respectively.

[0156] The lipid-lowering effect of red raspberry puree was evaluated. The optimal addition amount was 0.15 g, the optimal adsorption time was 60 min, and at the optimal combination, the binding rates of sodium taurocholate and sodium glycocholate in red raspberry puree were 49.36% and 61.82%, respectively.

[0157] Calculations show that compared with red raspberry puree, the optimal addition amount of red raspberry fresh fruit fermented jam is reduced by 20%; at the optimal combination, the binding rates of sodium taurocholate and sodium glycocholate in red raspberry fresh fruit fermented jam are increased by 11.61% and 5.74%, respectively.

[0158] The above experiments show that compared with red raspberry raw fruit pulp, the lipid-lowering function of red raspberry fresh fruit fermented jam is significantly improved.

[0159] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing red raspberry fresh fruit fermented jam, characterized in that: The specific steps include: (1) Collecting fresh red raspberry fruits that are mature, uniform in size, free of mechanical damage and pests and diseases, and dark red in color, soaking them in water to remove branches, leaves and soil, repeatedly rinsing them, and then taking them out and draining them to obtain red raspberry fruits; (2) beating the red raspberry fruits into a homogenate, boiling, and sterilizing to obtain the red raspberry raw fruit pulp, which is set aside; (3) mixing Lactobacillus plantarum, Lactobacillus paracasei and Lactobacillus acidophilus to obtain a mixed strain; The mass ratio of Lactobacillus plantarum, Lactobacillus paracasei and Lactobacillus acidophilus is 2:1:1; (4) diluting the mixed strains with water, and then inoculating the mixed strains into the raw red raspberry pulp for fermentation to obtain a red raspberry fermentation liquid; The mass ratio of the mixed bacteria to water is 1:250; The dosage ratio of the mixed strain to the red raspberry pulp is 0.2U:1L; The fermentation temperature is 39°C and the fermentation time is 80 hours; (5) adding white sugar, citric acid, vitamin C and xanthan gum to the red raspberry fermentation liquid, mixing and stirring to obtain the red raspberry fresh fruit fermented jam; Based on the mass of the red raspberry fermentation liquid being 100%, the masses of the white sugar, citric acid, vitamin C and xanthan gum are 17%, 1%, 0.3% and 0.3% respectively.

2. The method for preparing a fermented red raspberry jam according to claim 1, wherein: In step (2), the mixture is boiled until slightly thick.

3. The method for preparing a fermented red raspberry jam according to claim 1, wherein: In step (2), the sterilization temperature is 95° C. and the time is 20 min.

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