A functional lactic acid bacteria goat milk powder and its preparation method

Abstract

The present invention discloses a functional lactic acid bacteria goat milk powder and a preparation method thereof, belonging to the field of food processing. Acer truncatum Bunge seed oil and xylo-oligosaccharide have relatively high viability of bacteria, and together with skim milk powder, and the anti-thermal protection mechanisms of saccharides, proteinaceous and oily protectants are different. To fully exert the protection effect of the composite anti-thermal protectant, the present invention combines Acer truncatum Bunge seed oil, xylo-oligosaccharide and skim milk powder as the composite anti-thermal protectant to further improve the anti-thermal protection effect on bacteria. The present invention provides a functional lactic acid bacteria goat milk powder with a high viable bacteria rate and good stability.

Description

Technical Field

[0001] The present invention belongs to the field of food processing, and particularly relates to a functional lactic acid bacteria goat milk powder and a preparation method thereof. Background Art

[0002] The functions of lactic acid bacteria have been recognized by the public. Yogurt is considered to be an ideal nutritional functional food because it contains a large number of active lactic acid bacteria. However, due to the short shelf life of yogurt, the preparation of lactic acid bacteria milk powder by drying is beneficial for storage and transportation. Lactic acid bacteria have strict nutritional requirements and weak resistance to adverse environments, and are very sensitive to both low temperature and high temperature. High-temperature spray drying is used in the production of milk powder, with the inlet air temperature being 160-180°C, and the survival rate of lactic acid bacteria is very low. Therefore, it is necessary to add heat-resistant protectants to improve its survival rate and the viable count in the milk powder.

[0003] The heat-resistant protectants for lactic acid bacteria mainly include single protectants (such as glucose, fructose, lactose, mannose, sucrose, sorbitol, trehalose, wolfberry polysaccharide, glycerol, etc.), compound protectants (such as sucrose + maltodextrin, etc.), and the components of compound protectants are generally skim milk, arabic gum, sodium glutamate, and starch, etc. Chen He et al. used the Plackett-Burman test to analyze the protective effects of six common heat-resistant protectants, sucrose, skim milk powder, glucose, trehalose, gelatin, and glycerol, on Lactobacillus plantarum L61. The results determined the optimal protection formula for Lactobacillus casei L61, and the optimal addition amounts were 18 g / L of skim milk, 6% of glucose, and 13 mL / L of glycerol, and the survival rate of the bacteria reached 8.23%. Fan Na et al. studied the heat-resistant protection effects of trehalose, gelatin, and glycerol as heat-resistant protectants on the mixed bacteria of Lactobacillus acidophilus and Bifidobacterium. The research found that their combined effect was better than the single addition effect, and the survival rate could reach 16.58%. Cui Li et al. optimized three heat-resistant protectants, Fengxian burdock powder, glucose, and Peixian burdock powder, which had the best protection effect on Lactobacillus paracasei FM-LP-4. The optimal addition amounts of the compound protectant were: 2.0% of Fengxian burdock powder, 4% of glucose, and 2.0% of Peixian burdock powder. After heat treatment at 75°C for 10 min, the viable count could reach 6.33 lgCFU / mL.

[0004] The oil of Acer truncatum Bunge is rich in nervonic acid. Scientists around the world recognize that nervonic acid is the core natural component of brain nerve fibers and nerve cells, and it is also the only miraculous substance with dual effects that can repair and dredge damaged brain nerve fibers and promote the regeneration of nerve cells. The lack of nervonic acid will cause brain diseases such as sequelae of stroke, cerebral palsy, brain atrophy, memory decline, insomnia and amnesia. The "NANE Nervonic Acid Brain Power Tablets" produced and marketed in the United States are professionally researched and formulated by an American medical nutrition and health product R & D company and produced by the Boston Biomedical Research Institute in the United States. The product contains high-quality nervonic acid extracted from Chinese Acer truncatum Bunge trees and is targeted at people with memory decline, forgetfulness, thinking disorders, senile dementia, Parkinson's disease, brain atrophy, hemiplegia of limbs, language disorders, facial distortion, headache and dizziness caused by neurodegenerative diseases and nerve injuries, and is also used for brain hypoplasia, developmental delay, brain trauma, etc. The product has successfully entered the international market.

[0005] The content of vitamin E in the oil of Acer truncatum Bunge is 125.23mg / 100g, which is much higher than that of imported olive oil and palm oil and ranks among the top in domestic edible vegetable oils. Vitamin E, also known as tocopherol, has functions such as anti-infertility, prevention of coronary heart disease and cancer, and has become a research hotspot in contemporary drugs and nutritional products. At the same time, vitamin E itself is an excellent natural antioxidant and plays a positive role in extending the shelf life of oils. Therefore, the oil of Acer truncatum Bunge is particularly resistant to storage. The crude oil after a single fine filtration can be stored for 3 years without rancidity and deterioration at room temperature in the dark, indicating its strong antioxidant stability. The oil of Acer truncatum Bunge contains a variety of active ingredients, is rich in nervonic acid, the content of unsaturated fatty acids is over 90%, and is rich in vitamin E, which can protect cells against oxidative stress caused by free radicals and improve cognitive function. Nervonic acid can completely penetrate the blood-brain barrier to repair damaged nerve fibers, keep the brain pathways unobstructed, repair aging, damaged and hardened cardiovascular and cerebrovascular walls, restore vascular elasticity and regulate blood lipids. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art and provide a functional lactic acid bacteria goat milk powder and its preparation method.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A preparation method of a functional lactic acid bacteria goat milk powder includes the following steps:

[0009] (1) Prepare sour goat milk

[0010] (2) Prepare the functional lactic acid bacteria goat milk powder by spray drying

[0011] Add 3 - 5 ml of Acer truncatum Bunge seed oil, 7 - 11 g of fructooligosaccharide and 200 - 300 g of skim milk powder per 1000 g of sour goat milk as a heat protection agent, homogenize for 5 - 10 min, and then spray dry to collect the functional lactic acid bacteria goat milk powder.

[0012] Further, the specific operation of step (1) is as follows:

[0013] Sterilize fresh goat milk at 90℃ - 100℃ for 15 - 20 min and cool it to 40 - 45℃, then inoculate the activated starter culture at an inoculation amount of 5% - 10% (v / v), shake well, and ferment at 40 - 43℃ until the pH reaches 4.5, then stop fermentation to obtain sour goat milk.

[0014] Further, the starter culture is Lactobacillus bulgaricus and Streptococcus thermophilus.

[0015] Further, the conditions for spray drying in step (2) are:

[0016] Inlet temperature 120 - 130℃, outlet temperature 70 - 90℃, fan 90%, compressor air pressure 0.3 MPa.

[0017] Further, in step (2), the addition amount of xylooligosaccharide is 8.9 g, the addition amount of Acer truncatum Bunge seed oil is 3.7 mL, and the addition amount of skim milk powder is 272 g. The survival rate of lactic acid bacteria in the prepared functional lactic acid bacteria goat milk powder is as high as 73.12 ± 1.23%, and the viable bacteria count is as high as (3.08 ± 0.32)×10 9 CFU / g.

[0018] A functional lactic acid bacteria goat milk powder is prepared according to the above - mentioned preparation method of the functional lactic acid bacteria goat milk powder.

[0019] Further, the survival rate range of lactic acid bacteria per unit volume of the functional lactic acid bacteria goat milk powder is 47.5% - 72.8%, and the viable bacteria count per unit of bacterial powder is 1.96×10 9 CFU / g - 3.40×10 9 CFU / g.

[0020] Further, the shelf life of the functional lactic acid bacteria goat milk powder at 4℃ is as high as 1320 days, at 18℃ is as high as 323 days, and at 25℃ is as high as 165 days.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention provides a functional lactic acid bacteria goat milk powder and a preparation method thereof. Acer truncatum Bunge seed oil and xylo-oligosaccharide have relatively high survival rates for bacteria. Together with skim milk powder, and since the anti-thermal protection mechanisms of saccharides, protein-based, and oil-based protectants are different, to fully exert the protection effect of the composite anti-thermal protectant, the present invention combines Acer truncatum Bunge seed oil, xylo-oligosaccharide, and skim milk powder as a composite anti-thermal protectant to further improve the anti-thermal protection effect on bacteria.

[0023] Further, in step (2), the addition amount of xylo-oligosaccharide is 8.9 g, the addition amount of Acer truncatum Bunge seed oil is 3.7 mL, and the addition amount of skim milk powder is 272 g. The survival rate of lactic acid bacteria in the prepared functional lactic acid bacteria goat milk powder is as high as 73.12 ± 1.23%, and the viable count is as high as (3.08 ± 0.32) × 10 9 CFU / g.

[0024] The present invention provides a functional lactic acid bacteria goat milk powder with a high viable rate and good stability. The survival rate range of lactic acid bacteria in the goat milk powder is 47.5% - 72.8%, and the viable count per unit of bacterial powder is 1.96 × 10 9 CFU / g - 3.40 × 10 9 CFU / g, both higher than the national standard (≥ 1.0 × 10 6 CFU / g). Description of the Drawings

[0025] Figure 1 Shows the effect of Acer truncatum Bunge seed oil on the viable count and survival rate of acid goat milk;

[0026] Figure 2 Shows the effect of xylo-oligosaccharide on the viable count and survival rate of acid goat milk;

[0027] Figure 3 Shows the effect of xylo-oligosaccharide, Acer truncatum Bunge seed oil, and skim milk powder on the survival rate of lactic acid bacteria;

[0028] Figure 4 Shows the accelerated test of the functional lactic acid bacteria goat milk powder, where Figure 4 a: Graph of the change in viable count over time, Figure 4 b: Arrhenius graph. Detailed Embodiments

[0029] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] It should be noted that the terms "first", "second", etc. in the description, claims and the above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0031] Currently, the optimization of heat protection agents for lactic acid bacteria only considers their survival rate for lactic acid bacteria, without considering the functionality while selecting the protection agent. Based on this, the present invention uses the new food raw material Acer truncatum Bunge seed oil and the super bifidus factor - prebiotic xylo-oligosaccharide as the heat protection agent for lactic acid bacteria in acidified goat milk to improve the survival rate of lactic acid bacteria and the viable count in goat milk powder. In addition, the added protection agents Acer truncatum Bunge seed oil and xylo-oligosaccharide can further improve the functionality of lactic acid bacteria goat milk powder.

[0032] The following further describes the present invention in detail with reference to the drawings:

[0033] The present invention provides a method for preparing a functional lactic acid bacteria goat milk powder, comprising the following steps:

[0034] 1. Preparation of acidified goat milk

[0035] Sterilize fresh goat milk at 90°C - 100°C for 15 - 20 min and cool it to 40 - 45°C, then inoculate the activated starter culture (Lactobacillus bulgaricus and Streptococcus thermophilus) at an inoculation amount of 5% - 10% (v / v), shake well, ferment at 40 - 43°C for 4 - 6 h until the pH reaches 4.5, and then stop fermentation to obtain acidified goat milk, with a viable count of 2.05×10 9 -2.42×10 9 CFU / g.

[0036] 2. Preparation of functional lactic acid bacteria goat milk powder by spray drying

[0037] Add Acer truncatum Bunge seed oil (3 - 5 ml), fructo-oligosaccharide (7 - 11 g) and skimmed milk powder (200 g - 300 g) to every 1000 g of acidified goat milk, optimize the heat protection agent by the response surface method, homogenize for 5 - 10 min, and then spray dry (spray drying conditions: inlet temperature 120 - 130°C, outlet temperature 70 - 90°C, fan 90(%), compressor air pressure 0.3 MPa), and then collect the obtained functional lactic acid bacteria goat milk powder.

[0038] The present invention uses the following test methods to determine the activity and stability of the bacterial flora:

[0039] 1. Determination of the viable count of lactic acid bacteria

[0040] Take a certain amount of acidified goat milk or functional lactic acid bacteria goat milk powder and perform gradient dilution with sterile water. Then, select three different dilution degrees and use the MRS agar medium to determine the viable count by the plate spreading method. Make 3 parallels for each gradient, and then place them in a constant temperature incubator at 37°C for 48 h and then count.

[0041] 2. Determination of the stability of functional lactic acid bacteria goat milk powder

[0042] Pack the prepared functional lactic acid bacteria goat milk powder in small aluminum foil bags, and place them in a water bath at 45°C, 50°C, and 55°C respectively for heat preservation. Take 0.1 g of the bacterial powder every 2 h to measure the viable count per unit bacterial powder. Continuously measure 6 points, and make 3 parallels for each point. According to the measurement results, obtain the viable count of the functional lactic acid bacteria goat milk powder at different accelerated temperatures. Then, according to the first-order kinetic reaction equation (1) and the Arrhenius equation (2), calculate the inactivation rate constant of the bacteria in the functional lactic acid bacteria goat milk powder stored in the refrigerator (4°C) and at room temperature (18°C and 25°C), and analyze its stability.

[0043] First-order reaction kinetic equation:

[0044] lg N t -lgN o =kt (1)

[0045] Arrhenius equation:

[0046]

[0047] In the formula:

[0048] N0 —— viable count of functional lactic acid bacteria goat milk powder (CFU / g);

[0049] Nt —— viable count at time t (CFU / g);

[0050] t —— sampling time (h);

[0051] k and k0 —— rate constants (h-1);

[0052] Ea —— activation energy (J / mol);

[0053] R —— ideal gas constant (J / mol·K);

[0054] T —— absolute temperature (K).

[0055] 3. Analysis of the Activity Protection of Acer truncatum Bunge Seed Oil on Lactic Acid Bacteria in Sour Goat Milk

[0056] Add the fermented sour goat milk to Acer truncatum Bunge seed oil at 0%, 0.2%, 0.4%, 0.6%, and 0.8% (w / v) respectively, mix well, place it in a water bath at 75 °C for heat treatment for 10 min, then take it out and quickly cool it to room temperature, conduct plate counting, and finally calculate the survival rate of the bacteria. The results are as Figure 1 shown.

[0057] As Figure 1 can be seen, adding a certain amount of xylooligosaccharide can significantly increase the viable bacteria count and the survival rate of the bacteria in the fermented milk per unit volume. With the increase of the addition amount of xylooligosaccharide, the viable bacteria count and the survival rate of the bacteria both increase rapidly. When the addition amount of xylooligosaccharide is 0.9%, the viable bacteria count and the survival rate both reach the maximum, which are 1.21×10 9 cfu / mL and 57.6% respectively. When the addition amount of xylooligosaccharide exceeds 0.9%, the viable bacteria count and the survival rate of the bacteria tend to be stable.

[0058] In view of the relatively high survival rate of Acer truncatum Bunge seed oil and xylooligosaccharide on the bacteria, combined with skim milk powder, and the different heat protection mechanisms of sugars, protein-based, and oil-based protectants, in order to give full play to the protection effect of the composite heat protection agent, choose the combination of Acer truncatum Bunge seed oil, xylooligosaccharide, and skim milk powder as the composite heat protection agent to further improve the heat protection effect on the bacteria.

[0059] 4. Optimization of the Heat Protection Agent for Sour Goat Milk by Response Surface Methodology

[0060] According to the results of the single-factor experiment, select xylooligosaccharide (A), Acer truncatum Bunge seed oil (B), and skim milk powder (C) as independent variables, and the survival rate as the response value. Use Design Export software to design a Box-Behnken model with three factors and three levels. The levels of each factor are shown in Table 1, and the response surface design and results are shown in Table 2.

[0061] Table 1 Factor Level Table for Optimizing the Heat Protection Agent of Sour Goat Milk by Central Composite Experiment

[0062]

[0063] Table 2 Experimental Design and Results for Optimizing the Formula of the Heat Protection Agent of Sour Goat Milk by Central Composite Experiment

[0064]

[0065] Perform a second-order regression analysis on the response value results of the above 17 groups of experiments, establish a regression model for the survival rate R1, and obtain the following regression equation:

[0066] R1 = 72.02 + 0.16A - 6.36B + 3.22C + 1.27AB - 1.45AC - 1.1BC - 1.35A 2 - 12.95B 2 - 4.52C 2

[0067] In the equation, R1 represents the survival rate of bacteria per unit volume. A, B, and C represent the addition amounts of xylo - oligosaccharide, Acer truncatum Bunge seed oil, and skim milk powder respectively.

[0068] Analysis of variance was carried out on the regression equation to verify the reliability of the model, and the results are shown in Table 3.

[0069] Table 3 Analysis of variance table for the survival rate model of acidified goat milk

[0070]

[0071] Note: * Significant (p < 0.05); ** More significant (p < 0.01); *** Extremely significant (p < 0.001)

[0072] It can be seen from the analysis of variance in Table 3 that in the analysis of variance of the survival rate response surface model, the P - value of the regression equation model is < 0.0001, and this model is extremely significant. The lack - of - fit term P = 0.2672 > 0.05, and the lack - of - fit term is not significant, indicating that this model can be used. The determination coefficient R 2 = 0.9814, indicating that this model can be used to explain 98.14% of the response value changes. The adjusted determination coefficient R adj 2 = 0.9574, which is close to the R 2 value, indicating that the model has a high fitting degree. It can be seen from the table that the influence of the three factors on the response value of the survival rate from large to small is: Acer truncatum Bunge seed oil (B) > skim milk powder (C) > xylo - oligosaccharide (A). The quadratic term B 2 has an extremely significant influence on the survival rate, and C 2 is more significant.

[0073] The contour plots are all oval, indicating that there is an interaction between A, B, and C, and the 3D response surface graph presents an arch, indicating that the response value of the survival rate first increases and then decreases with the change of each factor, and there is a maximum value.

[0074] Within the test ranges of xylo - oligosaccharide, Acer truncatum Bunge seed oil, and skimmed milk powder, the survival rate range of lactic acid bacteria in the obtained functional lactic acid bacteria milk powder is 47.5% - 72.8%, and the viable count of bacteria per unit powder is 1.96×10 9 CFU / g - 3.40×10 9 CFU / g, which are all higher than the national standard (≥1.0×10 6 CFU / g).

[0075] Preferably, through Design-expert software, the regression equation was analyzed to obtain the predicted values of the heat-resistant protective agent formula for acid goat milk. The optimal addition amounts of each heat-resistant protective agent component per kg of acid goat milk were predicted to be 8.87 g of xylo-oligosaccharide, 3.73 mL of Acer truncatum seed oil, and 272 g of skim milk powder. Under these conditions, the survival rate of lactic acid bacteria in acid goat milk reached 73.53%, and the viable count was 3.11×10 9 CFU / g. For ease of adjusting each condition during the experiment, a verification experiment was designed. The addition amounts of xylo-oligosaccharide, Acer truncatum seed oil, and skim milk powder per 1 kg of acid goat milk were 8.9 g, 3.7 mL, and 272 g, respectively. The survival rate of lactic acid bacteria per unit volume was measured to be 73.12±1.23%, and its viable count was (3.08±0.32)×10 9 CFU / g. The actual value was close to the predicted value, indicating that it is feasible to prepare functional lactic acid bacteria goat milk powder by adding functional oils and prebiotics.

[0076] 5. Stability analysis of functional lactic acid bacteria goat milk powder

[0077] The accelerated test was used to predict the shelf life of functional lactic acid bacteria goat milk powder and analyze its stability. At 45°C, 50°C, and 55°C, 0.1 g of lactic acid bacteria milk powder was taken every 2 h for gradient dilution to measure its viable count. The results are as Figure 4 shown.

[0078] Functional lactic acid bacteria goat milk powder was placed at three temperatures of 45°C, 50°C, and 55°C, and the total viable count of the starter culture was measured at different times. According to the formula, with the logarithm of the ratio of the total viable count per unit (Nt) at each time point to the initial total viable count per unit (No) as the ordinate and time as the abscissa, a Figure 4 (a) was plotted. It can be seen from the figure that lg(Nt / No) decreases with the extension of time. The slopes of the equations in the figure are the inactivation rate constants at different temperatures: k 45 =-0.1155 (R 2 =0.984), k 50 =-0.1658 (R 2 =0.992), k 55 =-0.2039 (R 2 =0.993). According to formula (2), the reciprocal of the absolute value of the logarithm of the inactivation rate constant at different temperatures (lgk) was calculated. With 1 / T as the abscissa and lgk as the ordinate, a Figure 4 (b) was plotted. The equation was: y = -5941.9x + 16.541 (R 2= 0.9786), the inactivation rate constants k4 = 1.26×10 of the bacterial powder at 4°C, 18°C and 25°C can be deduced -5 , 1.36×10 -4 and k 25 = 4.09×10 -4 . It is predicted that the shelf lives of the functional lactic acid bacteria goat milk powder at 4°C, 18°C and 25°C are 1320 days, 323 days and 165 days respectively. Thus, it can be seen that the functional lactic acid bacteria goat milk powder has good stability.

[0079] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention fall within the protection scope of the claims of the present invention.

Claims

1. A preparation method of a functional lactic acid bacteria goat milk powder, characterized in that, It includes the following steps: (1) Prepare acidified goat milk; (2) Prepare functional lactic acid bacteria goat milk powder by spray drying: Based on every 1000 g of acidified goat milk, add 8.9 g of xylo-oligosaccharide, 3.7 mL of Acer truncatum Bunge seed oil, and 272 g of skim milk powder. Add xylo-oligosaccharide, Acer truncatum Bunge seed oil, and skim milk powder as heat-resistant protectants, homogenize for 5 min - 10 min, and then conduct spray drying to collect the functional lactic acid bacteria goat milk powder; The specific operation of step (1) is: Sterilize fresh goat milk at 90°C - 100°C for 15 min - 20 min and cool it to 40°C - 45°C, then inoculate the activated starter culture at an inoculation amount of 5% - 10% (v / v), shake well, ferment at 40°C - 43°C until the pH reaches 4.5, and then stop fermentation to obtain acidified goat milk; The starter culture is Lactobacillus bulgaricus and Streptococcus thermophilus; The conditions for spray drying in step (2) are: inlet temperature 120°C - 130°C, outlet temperature 70°C - 90°C, fan 90%, compressor air pressure 0.3 MPa; The survival rate range of the functional lactic acid bacteria in the goat milk powder per unit volume is 73.12±1.23%, and the viable bacteria count per unit of bacterial powder is (3.08±0.32)×10 9 CFU / g.

2. A functional lactic acid bacteria goat milk powder, characterized in that, It is prepared according to the preparation method of the functional lactic acid bacteria goat milk powder described in claim 1.

3. The functional lactic acid bacteria goat milk powder according to claim 2, wherein The survival rate range of lactic acid bacteria in the functional lactic acid bacteria goat milk powder per unit volume is 73.12±1.23%, and the viable bacteria count per unit of bacterial powder is (3.08±0.32)×10 9 CFU / g.

4. The functional lactic acid bacteria goat milk powder according to claim 2, wherein The shelf life of the said functional lactic acid bacteria goat milk powder is 1320 days at 4°C, 323 days at 18°C, and 165 days at 25°C.

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