Litchi flavor protein powder containing gamma-aminobutyric acid as well as preparation method and application thereof

Abstract

The invention discloses litchi flavor protein powder containing gamma-aminobutyric acid as well as a preparation method and application of the litchi flavor protein powder. The preparation method comprises the following steps: weighing the following raw materials in parts by mass: 10-40 parts of soybean protein isolate, 15-45 parts of whey protein concentrate, 1-22 parts of litchi powder, 16-26 parts of whole milk powder, 0.5-5 parts of an emulsifier, 3-10 parts of fructo-oligosaccharide, 1-9 parts of xylitol and 0.1-1 part of stevioside; the raw material components are mixed to obtain the lychee flavor protein powder containing gamma-aminobutyric acid. According to the preparation method, gamma-aminobutyric acid is also provided while the defects of single raw material and single taste are made up by adding soybean protein isolate, concentrated whey protein and litchi powder; the nutritional value of the protein powder is improved, the taste, solubility and texture state of the protein powder are improved, and the comprehensive effects of improving sleep, relieving mood, regulating blood pressure and promoting growth hormone secretion are expected to be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and particularly relates to a litchi-flavored protein powder containing gamma-aminobutyric acid, and a preparation method and application thereof. Background Art

[0002] Protein powder is usually made from ingredients such as soy protein isolate and whey protein concentrate, and has the characteristics of replenishing energy and enhancing physical fitness. Consuming protein powder can increase satiety, and is especially suitable for fitness enthusiasts who need to gain muscle, reduce carbohydrate intake, and improve metabolism. In addition, protein powder is rich in protein and multiple amino acids, and can be used as a nutritional supplement for the elderly, children, and pre- and post-operative patients. Plant protein is easily digested and absorbed by the human body. Nutritionists believe that increasing the intake of plant protein, especially soy protein isolate, is one of the effective ways to solve cardiovascular and cerebrovascular diseases, obesity, diabetes and other problems. The addition of animal protein makes up for the disadvantages of insufficient types and content of essential amino acids in single plant protein. However, most of the protein powders on the market are single soy protein isolate powder or whey protein concentrate powder, and dual protein powder is relatively scarce and urgently needs to be further improved.

[0003] Insomnia has now become a key issue affecting the quality of life and health of human beings, and its prevalence rate is rising year by year. High-quality sleep is an important prerequisite for people to have a high standard of life. Studies have shown that sleep is affected by a variety of neuronal projections and neurochemical transmitters. The amino acid neurotransmitter γ-aminobutyric acid (GABA) is present in almost all neurons in the brain. It is the most important neurotransmitter involved in the sleep-wake circadian rhythm and has the effect of promoting cerebral cortical inactivation and behavioral quiescence. Increased GABA content can increase deep slow-wave sleep. In addition, GABA also has great advantages in the treatment of human mental illness. As an inhibitory neurotransmitter, it can protect over-excited neurons, and has the functions of improving brain activity, calming, detoxification, etc. It can also be anti-anxiety, anti-depression and anti-epileptic, and has extremely low side effects.

[0004] Lychee (litchi chinensis Sonn.), a member of the Sapindaceae family, is a specialty fruit of South China, commonly known as the "King of Lingnan Fruits." Rich in water and nutrients, lychees ripen during the hottest seasons, resulting in a short shelf life and the frequent occurrence of "high yields but low harvests." Rich in gamma-aminobutyric acid, polysaccharides, polyphenols, dietary fiber, and other active nutrients, lychees are known as "China's Treasures." Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a method for preparing lychee-flavored protein powder containing gamma-aminobutyric acid. By adding soy protein isolate, whey protein concentrate, and lychee powder, this preparation method not only compensates for the drawbacks of a single raw material and a single flavor, but also provides gamma-aminobutyric acid. This method not only increases the nutritional value of the protein powder, but also improves its taste, solubility, and texture. It is expected to achieve the combined effects of improving sleep, soothing emotions, regulating blood pressure, and promoting growth hormone secretion.

[0006] The present invention also provides litchi-flavored protein powder containing gamma-aminobutyric acid prepared by the above preparation method.

[0007] The present invention also provides an application.

[0008] According to a first aspect of the present invention, a method for preparing lychee-flavored protein powder containing γ-aminobutyric acid is provided, the method comprising the following steps:

[0009] The following raw materials are weighed in parts by mass: 10-40 parts of soy protein isolate, 15-45 parts of whey protein concentrate, 1-22 parts of lychee powder, 16-26 parts of whole milk powder, 0.5-5 parts of emulsifier, 3-10 parts of oligofructose, 1-9 parts of xylitol and 0.1-1 part of stevioside; and the raw materials are mixed to obtain lychee-flavored protein powder containing gamma-aminobutyric acid.

[0010] In some embodiments of the present invention, the preparation method includes weighing the following raw materials by mass fraction: 20-25 parts of soy protein isolate, 22-28 parts of concentrated whey protein, 14-18 parts of lychee powder, 18-24 parts of whole milk powder, 1-2 parts of emulsifier, 4-8 parts of oligofructose, 4-8 parts of xylitol and 0.15-0.3 parts of steviol glycoside; mixing the raw material components to obtain lychee-flavored protein powder containing γ-aminobutyric acid.

[0011] The soy protein isolate is a plant-based protein extracted from soybeans and is known as "plant meat". It is rich in various essential amino acids for the human body and does not contain cholesterol.

[0012] Lychee is rich in various active substances such as γ-aminobutyric acid, polysaccharides, polyphenols and dietary fiber, and its application in protein powder has multiple advantages. On the one hand, γ-aminobutyric acid (GABA) is an important neurotransmitter that regulates the sleep-wake circadian rhythm, and has the effect of promoting cerebral cortical inactivation and behavioral quiescence. Studies have shown that an increase in GABA content can improve the quality of deep slow-wave sleep. Since many people who exercise and lose weight often suffer from insomnia, adding lychee powder rich in γ-aminobutyric acid to protein powder can not only enhance the function of protein powder, but also improve sleep quality, making it more suitable for the needs of people who exercise and lose weight, while also contributing to physical and mental health. On the other hand, the polysaccharides in lychee have significant antioxidant, immune-regulating, and blood sugar-lowering effects.

[0013] In some embodiments of the present invention, the preparation method of lychee powder comprises the following steps: fresh lychees are shelled and pitted, and then pulped into lychee pulp; a drying agent is added to the lychee pulp, and the mixture is spray-dried to obtain lychee powder.

[0014] In some embodiments of the present invention, the variety of litchi is selected from at least one of Baila, Baitangpeng, Feizishao, Heiye, and Jizuili.

[0015] In some embodiments of the present invention, the drying aid comprises at least one of maltodextrin, whey protein concentrate, gum arabic and soy protein.

[0016] In some embodiments of the present invention, the added amount of the drying aid is 15% to 20% of the mass of the litchi pulp.

[0017] In some embodiments of the present invention, the emulsifier includes at least one of soybean lecithin, gum arabic, gelatin, sodium carboxymethyl cellulose and sodium alginate.

[0018] In some embodiments of the present invention, the whey protein concentrate includes at least one of WPC80, WPC35 and WPC90.

[0019] In some embodiments of the present invention, the soy protein isolate and the whey protein concentrate are passed through a 70-90 mesh sieve before mixing.

[0020] In some embodiments of the present invention, the xylitol is passed through a 90-110 mesh sieve before mixing.

[0021] In some embodiments of the present invention, the basic components of the lychee powder, based on 100 g, include: 45-55 mg of γ-aminobutyric acid, 0.5-1 g of protein, 0.3-0.8 g of ash, 0.05-0.2 g of fat, and 95-99 g of total sugar.

[0022] According to a second aspect of the present invention, a lychee-flavored protein powder containing γ-aminobutyric acid prepared by the preparation method described in the first aspect of the present invention is provided.

[0023] In some embodiments of the present invention, the content of γ-aminobutyric acid in the lychee-flavored protein powder is 40 to 100 μg / g.

[0024] In some embodiments of the present invention, the particle size D(3,2) of the lychee-flavored protein powder is 20 to 30 μm.

[0025] In some embodiments of the present invention, the fat content of the lychee-flavored protein powder is 5% to 8%.

[0026] In some embodiments of the present invention, the solubility of the lychee flavored protein powder is 65% to 80%.

[0027] In some embodiments of the present invention, the ash content of the litchi flavored protein powder is 2% to 3%.

[0028] According to the third aspect of the present invention, the application of the preparation method described in the first aspect of the present invention in any one of (1) to (4) is proposed:

[0029] (1) preparing products that help improve sleep;

[0030] (2) preparing products that help control body fat;

[0031] (3) preparing products that help enhance immunity;

[0032] (4) The preparation helps maintain healthy blood pressure levels.

[0033] The present invention has at least the following beneficial effects:

[0034] The addition of soy protein isolate to the γ-aminobutyric acid-containing lychee-flavored protein powder provided by the present invention increases the protein content and protein utilization rate of the protein powder. The combination of soy protein isolate and whey protein concentrate avoids the disadvantage of a single nutritional structure, reduces the beany smell, and achieves complementary protein nutrition. It has low production costs, good flavor, and a delicate taste, which helps to create better economic value for the processing and utilization of soybean by-products. The present invention further improves the nutritional value of the protein powder by adding active substances including lychee powder, providing consumers with a high-protein, high-nutrition, and health-promoting high-quality food.

[0035] The lychee-flavored protein powder of the present invention is rich in gamma-aminobutyric acid, which can effectively improve sleep quality. The protein powder formula not only contains two proteins, but also has a high protein digestibility, significantly increasing the variety of amino acids, effectively removing the beany smell of traditional protein powder, while giving the product a unique lychee flavor. Furthermore, the protein powder has the characteristics of high protein content, low fat, and low calories, making it not only suitable for people who are fitness and weight loss, but also particularly suitable for the elderly, children, and pre- and postoperative patients, fully meeting the nutritional needs of a variety of populations. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0037] Figure 1 This is a sensory scoring chart in the test example of the present invention;

[0038] Figure 2 This is a chromatogram of the γ-aminobutyric acid standard product in the test example of the present invention;

[0039] Figure 3 This is a standard curve of γ-aminobutyric acid in the test examples of the present invention;

[0040] Figure 4 This is a chromatogram of protein powder in a test example of the present invention;

[0041] Figure 5 This is an electronic tongue radar image of the protein powder in the test example of the present invention;

[0042] Figure 6 This is an infrared image of the protein powder in the test example of the present invention;

[0043] Figure 7 This is a particle size diagram of the protein powder in the test example of the present invention. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0045] Example 1

[0046] This embodiment provides a lychee-flavored protein powder containing γ-aminobutyric acid, and the preparation method thereof comprises the following steps:

[0047] (1) Fresh Feizixiao lychees were shelled and pitted, and then beaten into lychee pulp. Maltodextrin, a drying aid, was added to the lychee pulp, and then spray-dried to obtain lychee powder. The amount of maltodextrin added was 18% of the mass of the lychee pulp.

[0048] (2) By mass, 23 parts of soy protein isolate (purchased from Photosynthetic Biology, item number A105), 25 parts of WPC 80 whey protein concentrate (purchased from Yulin Holdings, material number: 1001615), 16 parts of lychee powder, 21 parts of whole milk powder (purchased from NZMP), 2 parts of soy lecithin (purchased from Solae), 6 parts of oligofructose (purchased from Bailong Chuangyuan, item number 20230620026), 6 parts of xylitol (purchased from Tanghetang), and 0.2 parts of stevioside (purchased from Haotian Pharmaceutical) were weighed.

[0049] (3) Soy protein isolate and WPC 80 whey protein concentrate were passed through an 80-mesh sieve, and xylitol was passed through a 100-mesh sieve.

[0050] (4) The sieved soy protein isolate, whey protein concentrate and xylitol are mixed with the remaining raw materials to obtain lychee-flavored protein powder containing γ-aminobutyric acid.

[0051] Example 2

[0052] This embodiment provides a lychee-flavored protein powder containing γ-aminobutyric acid. The preparation method thereof is different from that of Example 1 only in that the amount of lychee powder is adjusted to 8 parts, and the remaining steps are the same as those of Example 1.

[0053] Example 3

[0054] This embodiment provides a lychee-flavored protein powder containing γ-aminobutyric acid. The preparation method thereof is different from that of Example 1 only in that the amount of lychee powder is adjusted to 12 parts, and the remaining steps are the same as those of Example 1.

[0055] Example 4

[0056] This embodiment provides a lychee-flavored protein powder containing γ-aminobutyric acid. The preparation method thereof is different from that of Example 1 only in that the amount of lychee powder is adjusted to 20 parts, and the remaining steps are the same as those of Example 1.

[0057] Comparative Example 1

[0058] This comparative example provides a protein powder, the preparation method of which differs from that of Example 1 only in that the lychee powder component is omitted, and the remaining steps are consistent with those of Example 1.

[0059] Test example

[0060] In this test example, the protein powders provided in Examples 1 to 4 and Comparative Example 1 were subjected to sensory evaluation, GABA measurement, protein digestibility measurement, electronic tongue flavor measurement, infrared spectroscopy analysis, particle size measurement, crude fat measurement, solubility measurement, and ash measurement. The litchi powder component prepared in Example 1 was subjected to GABA measurement, protein content measurement, ash content measurement, fat content measurement, and total sugar content measurement. The specific experimental methods and results are as follows:

[0061] 1. Sensory evaluation

[0062] Sensory evaluation was performed on the protein powders prepared in Examples 1-4 and Comparative Example 1.

[0063] According to the basic requirements of GB 10220-88 "General Theory of Sensory Analysis Methods", evaluators were selected and trained. Finally, 12 students with certain sensory evaluation experience were selected to form a sensory scoring team, 6 males and 6 females. They scored each sample according to the scoring criteria in Table 1, repeated 3 times, and the average value was calculated. The sensory scoring results were removed from the maximum and minimum values, and the average score of the remaining 10 sensory evaluators was taken. The results are as follows Figure 1 shown.

[0064] Table 1 Sensory evaluation table

[0065]

[0066] Depend on Figure 1 It can be seen that with the increase in the amount of litchi powder added, the sensory score of the protein powder shows a trend of "first rising and then falling"; when the mass fraction of litchi powder added is 16 parts, the sensory score of the protein powder reaches the highest value of 85.1 points. This is because the appropriate addition of litchi powder can enhance the sweetness and flavor of the protein powder, making it taste better and in line with the taste preferences of most consumers. When the amount of litchi powder added is too little, the sweetness of the protein powder is not prominent enough, and the unique flavor of the litchi powder cannot be fully displayed, thus affecting the overall sensory score. When the amount of litchi powder added is too much, the sweetness of the protein powder becomes too strong, covering up the flavor of the protein powder itself, and may cause flavor imbalance, thereby reducing the sensory score. In summary, the appropriate amount of litchi powder added is 16 parts. The protein powder with this amount of addition has a good overall flavor and effectively improves the sensory quality of the protein powder.

[0067] 2. HPLC Determination of γ-Aminobutyric Acid

[0068] The lychee powder prepared in Example 1 and the protein powders prepared in Example 1 and Comparative Example 1 were subjected to γ-aminobutyric acid determination using a high performance liquid chromatograph (Agilent 1260). A 500 mg / L GABA standard solution, a 0.4 mol / L boric acid solution, and a 20 mmol / L sodium acetate solution were prepared.

[0069] Derivatization reagent solution: weigh 0.1 g of o-phthalaldehyde, add 1 mL of acetonitrile and 130 μL of mercaptoethanol, and dilute to 10 mL with 0.4 mol / L boric acid buffer.

[0070] Pre-column derivatization: Measure 1 mL of sample and add 50 μL of o-phthalaldehyde derivatization reagent, shake thoroughly, and inject after passing through the membrane.

[0071] Chromatographic column: C18 (150 mm × 4.6 mm, 5 μm); mobile phase: A: 20 mmol / L sodium acetate solution, B: pure acetonitrile; flow rate: 0.8 mL / min; detection wavelength: 338 nm; column temperature: 30°C; injection volume: 10 μL; gradient elution program is shown in Table 2.

[0072] Table 2 Gradient elution program

[0073]

[0074] To draw the standard curve: pipette 0, 5, 10, 20, 40, 50, and 100 μL of 500 mg / L GABA standard solution into a 2 mL centrifuge tube, and add 1000, 995, 990, 980, 960, 950, and 900 μL of 0.4 mol / L boric acid buffer to make up to 1 mL. Then add 50 μL of o-phthalaldehyde derivatization reagent and shake thoroughly. After passing through the membrane, inject the sample to obtain the corresponding chromatographic peak. Draw the standard curve with the concentration of the standard solution as the horizontal axis and the corresponding peak area as the vertical axis. The derivatization chromatogram of the GABA standard is shown below. Figure 2 As shown, the GABA standard curve is as follows Figure 3 As shown, the derivatization chromatograms of the lychee powder prepared in Example 1 and the protein powder prepared in Example 1 and Comparative Example 1 are shown. Figure 4 shown.

[0075] Depend on Figure 2 It can be seen that the retention time of the GABA characteristic peak is between 14.20 and 14.35 min.

[0076] Depend on Figure 3 It can be seen that the regression equation of the GABA standard curve is y=20.931x-7.4891, and the correlation coefficient is 0.9992, indicating that γ-aminobutyric acid has a good linear relationship in the range of 0 to 50 μg / mL.

[0077] Depend on Figure 4It can be seen that the chromatographic peak of gamma-aminobutyric acid (box mark area in the figure) appeared in the lychee powder prepared by Example 1 and the protein powder prepared by Example 1 when the retention time was 14.20~14.35min. After calculation, the content of gamma-aminobutyric acid in the lychee powder of Example 1 is 512.80 μg / g, and the gamma-aminobutyric acid content in the protein powder prepared by Example 1 is 68.76 μg / g. The protein powder (comparative example 1) without adding lychee powder does not have gamma-aminobutyric acid chromatographic peak at retention time 14.20~14.35min, indicating that the protein powder without adding lychee powder does not contain gamma-aminobutyric acid. This may be because gamma-aminobutyric acid derives from lychee powder, rather than other ingredients in protein, so gamma-aminobutyric acid characteristic peak does not appear in the protein powder without adding lychee powder.

[0078] 3. Protein digestibility determination

[0079] The protein digestibility of the protein powders prepared in Example 1 and Comparative Example 1 was determined.

[0080] Protein digestibility determination experiments mainly use three types of simulated digestive fluids: simulated saliva (Simulated Salivary Fluid, SSF), simulated gastric fluid (Simulated Gastric Fluid, SGF), and simulated intestinal fluid (Simulated Intestinal Fluid, SIF).

[0081] To simulate oral digestion, mix the protein powder solution with SSF to a target final ratio of 1:1 (w / v). Add artificial salivary α-amylase to the mixture to a final concentration of 75 U / mL. Then, add 25 μL of 0.3 mol / L CaCl₂ and 975 μL of deionized water. Shake the mixture and incubate at 37°C for 2 minutes to obtain the oral digestion solution.

[0082] Simulated gastric digestion: Mix 10 mL of oral digestive fluid with 8 mL of SGF. Add porcine pepsin (to a final concentration of 2000 U / mL) and 5 μL of 0.3 mol / L CaCl₂. Adjust the pH of the mixture to 3 by adding 1 mol / L hydrochloric acid, recording the volume of hydrochloric acid used. Subsequently, bring the mixture to 20 mL with deionized water. Shake well and incubate at 37°C for 2 hours to obtain gastric digestion fluid.

[0083] Simulated intestinal digestion: 20 mL of uninactivated gastric digestive fluid was mixed with SIF and the pH was adjusted to 7 with 1 mol / L NaOH. The volume of NaOH used was recorded. 40 μL of 0.3 mol / L CaCl2 was added and the mixture was brought to 40 mL with deionized water. The mixture was shaken and incubated at 37°C for 2 hours. After incubation, the mixture was centrifuged at 10,000 rpm for 10 minutes at 4°C. 20 mL of supernatant was collected from each sample, flushed with nitrogen for 20 seconds, and stored at -20°C.

[0084] Determination of in vitro protein digestibility: Take the supernatant and determine the soluble protein content using the Kjeldahl method.

[0085]

[0086] It was determined that the protein digestibility of Example 1 was 72.87%±2.07%, while the protein digestibility of Comparative Example 1 was 77.74%±1.02%.

[0087] This difference may be due to the fact that litchi powder is rich in polysaccharides and dietary fiber. These components may bind to proteins in the gastrointestinal tract, forming complexes that reduce the contact efficiency between proteases and proteins, thereby affecting protein breakdown. Furthermore, polysaccharides and dietary fiber increase the viscosity of digestive fluids, inhibiting the diffusion of enzymes and further reducing the rate of protein digestion. Furthermore, the phenolic compounds in litchi powder may also inhibit the activity of proteases. These phenolic compounds may bind to digestive enzymes or proteins, forming complexes that are difficult to degrade, thereby affecting the efficiency of protein digestion and absorption.

[0088] 4. Electronic tongue flavor measurement

[0089] The taste of the protein powders prepared in Example 1 and Comparative Example 1 was measured using an electronic tongue system (SA402B, INSENT).

[0090] The electronic tongue sensor array includes electrochemical sensors for sour, salty, umami, bitter, astringent, bitter aftertaste, and astringent aftertaste, and two Ag / AgCl reference electrodes. The sensor element and secondary sensor process and integrate taste information, and construct a qualitative and quantitative model of taste information. Therefore, it can accurately express the sourness, saltiness, umami, bitterness, astringency, bitter aftertaste, and astringent aftertaste of the sample, and has the advantages of high sensitivity, high specificity and real-time monitoring.

[0091] The specific determination method is: weigh 10g of sample, add 150mL of deionized water, stir magnetically for 20min, centrifuge at 8000r / min for 10min, take the supernatant and pour it into the electronic tongue special cup for testing. In order to reduce the impact of environmental changes and ensure the stability of the test results, the electronic tongue needs to be activated, calibrated and diagnosed before testing. All samples are collected in parallel 5 times at (25±1)℃. The taste intensity data is collected using the data processing software that comes with the electronic tongue. The results are as follows: Figure 5 shown.

[0092] Depend on Figure 5 It can be seen that compared with Comparative Example 1, Example 1 has a high umami response value, a low salty response value, a higher richness value, and a low sour and bitter aftertaste, which is in line with the taste of the general public. Analysis of the reason may be that the polysaccharides contained in the lychee powder combine with the protein powder to reduce the saltiness, while the presence of polyphenols and other nutrients increases the richness of the protein powder. Therefore, according to the data from the electronic tongue, it can be seen that the lychee powder containing γ-aminobutyric acid has a good taste, a unique lychee flavor, and the overall sensory characteristics are more easily accepted by consumers.

[0093] 5. Infrared spectroscopy analysis

[0094] The protein powders prepared in Example 1 and Comparative Example 1 were subjected to infrared spectroscopy analysis using an infrared spectrometer (NICOLET tel S50, Thermo Fisher Scientific, Inc., USA). 3 mg of the ground protein powder was placed in an infrared spectrometer for ATR scanning, with air as the background for background subtraction. The scanning range was 350-4000 cm -1 , with a resolution of 4cm -1 , the number of scans is 32 times, and the results are as follows Figure 6 shown.

[0095] Depend on Figure 6 It can be seen that 3283cm -1 At 1742 cm, a strong broadband is generated by OH stretching vibration. -1 The band at 1637 cm indicates the presence of methyl ester groups, while the band at 1637 cm -1 The band at 1500cm indicates the presence of amino acid groups. -1 and 1700cm -1 The strong absorption peak between is the characteristic absorption peak of polygalactose, which has carbonyl and ether groups. In addition, compared with Comparative Example 1, the fatty acid characteristic region 2925cm -1 The vibration of the (CH2 and CH3) absorption peaks is weakened, indicating a decrease in fat content. Located at 3665cm -1The absorption peaks near (CH2 and CH3) shifted, representing the protein characteristic region 1742 cm -1 (C=O), fatty acid characteristic region 2925cm -1 The absorption peaks of (CH2 and CH3) weakened, 1588cm -1 and 1190cm -1 The vibration of the mixed area containing the vibration bands of fatty acids, proteins and polysaccharides changes, indicating that there is an obvious interaction between the litchi powder and the protein powder in Example 1, which affects the structure and functional properties of the protein powder, and further affects the taste, stability and sensory characteristics of the protein powder.

[0096] 6. Particle Size Determination

[0097] The particle size of the protein powder prepared in Example 1 and Comparative Example 1 was measured using a laser particle size analyzer (LS13320, Beckman Coulter, USA). The laser particle size analyzer is a novel particle size distribution testing device based on the laser diffraction method. Compared with traditional measuring equipment, the laser particle size analyzer has a simple testing method, a fast test speed, and good data reproducibility.

[0098] The specific determination method is: weigh 1g of sample into a 50mL beaker and add 15mL of 40℃ distilled water to dissolve it. To ensure the stability of the experimental data, the particle size analyzer needs to perform a self-test before testing the sample. After the instrument self-test is completed, add the sample. When the obscuration rate of the sample is stable at 8% to 13% and the polarized light intensity difference scattering (PIDS) is stable at 40% to 56%, the particle size analysis can be performed. The test results are as follows: Figure 7 shown.

[0099] Depend on Figure 7 It can be seen that the protein powders prepared in Example 1 of the present invention and Comparative Example 1 both showed a normal distribution, and the curve widths were relatively close, indicating that the particle size distribution was relatively uniform. The surface area average diameter D(3,2) of Comparative Example 1 was 28.41 μm, and D(3,2) of Example 1 was 26.54 μm. Compared with Comparative Example 1, the particle size distribution curve of Example 1 was shifted to the left as a whole, indicating that the addition of litchi powder made the protein powder solution finer in particle size, more small particle droplets, and a smoother protein powder solution.

[0100] 7. Crude fat determination

[0101] The lychee powder prepared in Example 1 and the protein powder prepared in Example 1 and Comparative Example 1 were measured using a crude fat analyzer (SZF-06).

[0102] Before use, the extraction cartridge must be dried at 100°C ± 5°C for 30 minutes. Cool in a desiccator for 0.5 hours before weighing. Weigh 1.5g of sample and place it into a filter paper cartridge. Stuff cotton balls at both ends to prevent spillage. Place the cartridge into an extraction cartridge filled with 50mL of petroleum ether. Place the cartridge in a crude fat analyzer and extract at 60°C for 4 hours. Then, dry the cartridge at 100°C ± 5°C for 1 hour. Calculate the fat content of the sample.

[0103] The result shows that the fat content of the lychee powder prepared by Example 1 of the present invention is 0.18% ± 0.003, the fat content of the protein powder prepared by Example 1 is 7.63% ± 0.014, and the fat content of the protein powder prepared by Comparative Example 1 is 10.11% ± 0.539. As can be seen from the fat content data of Example 1 and Comparative Example 1, the protein powder prepared by Example 1 has lower fat, weaker creaminess, and good protein powder mouthfeel. In addition, low-fat protein powder caters to the pursuit of "low / no / fat-reduced" food by modern consumers, thereby attracting more fitness and weight loss people, and becoming a product loved by consumers.

[0104] 8. Solubility Determination

[0105] The solubility of the protein powders prepared in Example 1 and Comparative Example 1 was measured.

[0106] Weigh 5.0 g of sample and add 75 mL of distilled water. Stir in a 40°C water bath for 30 min to ensure complete dispersion of the sample. After cooling, centrifuge at 6000 rpm for 10 min. Finally, take the supernatant and dry it at 105°C to constant weight.

[0107] After calculation, the solubility of the protein powder prepared in Example 1 of the present invention is 70.56%, and the solubility of the protein powder prepared in Comparative Example 1 is 64.95%. It can be seen from the solubility data of Example 1 and Comparative Example 1 that the solubility of Example 1 is significantly higher than that of Comparative Example 1. Analysis of the reasons may indicate that the addition of litchi powder can make the texture of the protein powder after mixing more uniform, the mouthfeel smoother, and the fluidity better, which is conducive to the mixing and consumption of the protein powder.

[0108] 9. Ash content determination

[0109] The ash content of the litchi powder prepared in Example 1 and the protein powder prepared in Example 1 and Comparative Example 1 was measured.

[0110] The ash content in protein powder is determined according to the method in GB5009.4-2016 "National Food Safety Standard - Determination of Ash Content in Foods". 3g of sample is weighed into a crucible that has been burned to constant weight. Heat on a hot plate with low heat until the sample is fully carbonized until smokeless. Then place it in a high-temperature furnace and burn at 550℃±25℃ for 4h. Cool to about 200℃, remove it, and cool it in a desiccator for 30min. Before weighing, if there are carbon particles in the burning residue, a small amount of water should be dripped into the sample to loosen the lumps. Evaporate the water and burn again until there are no carbon particles, indicating that the ash is complete. Only then can it be weighed. Repeat the burning until the difference between the two weighings before and after is no more than 0.5mg, which is constant weight.

[0111] The ash content of the litchi powder prepared in Example 1 was calculated to be 0.57% ± 0.004, the ash content of the protein powder in Example 1 was 2.89% ± 0.004, and the ash content of the protein powder in Comparative Example 1 was 3.37% ± 0.01. As can be seen from the ash data of Example 1 and Comparative Example 1, the ash content of Example 1 is lower, indicating that the mineral or inorganic salt content in Example 1 of the present invention is less, the quality of the protein powder is better, and it meets the requirements of national health standards.

[0112] 10. Protein Determination

[0113] According to the national standard GB5009.5-2016, the protein content of the litchi powder prepared in Example 1 was determined by the Kjeldahl method.

[0114] The protein content in the litchi powder prepared in Example 1 was calculated to be 0.90%±0.041.

[0115] 11. Determination of total sugar content

[0116] The total sugar content of the litchi powder prepared in Example 1 was determined using the phenol-sulfuric acid method. A 100 mg / L standard glucose working solution was prepared. 0 mL, 0.2 mL, 0.4 mL, 0.6 mL, 0.8 mL, and 1 mL of the standard glucose working solution were pipetted into 2 mL centrifuge tubes, respectively, and the volume was made up to 1 mL with distilled water. 1.0 mL of 5% phenol solution and 5 mL of concentrated sulfuric acid were then added to each test tube. After thorough mixing, the mixture was allowed to stand at room temperature for 10 minutes, followed by heating in a 30°C water bath for 20 minutes. After cooling to room temperature, the absorbance was measured at 490 nm. A standard curve was drawn with glucose mass concentration as the horizontal axis and absorbance as the vertical axis. The diluted litchi powder solution was treated in the same manner, and the absorbance was measured and then added to the standard curve to calculate the total sugar content.

[0117] The total sugar content of the litchi powder prepared in Example 1 was calculated to be 98.94%±0.387.

[0118] While the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A method for preparing litchi-flavored protein powder containing γ-aminobutyric acid, characterized in that: The preparation method comprises the following steps: The following raw materials are weighed in parts by mass: 10-40 parts of soy protein isolate, 15-45 parts of whey protein concentrate, 1-22 parts of lychee powder, 16-26 parts of whole milk powder, 0.5-5 parts of emulsifier, 3-10 parts of oligofructose, 1-9 parts of xylitol and 0.1-1 part of stevioside; and the raw materials are mixed to obtain lychee-flavored protein powder containing gamma-aminobutyric acid.

2. The preparation method according to claim 1, characterized in that The preparation method of the litchi powder comprises the following steps: shelling and core-removing fresh litchi, and beating the litchi pulp to obtain litchi pulp; adding a drying aid to the litchi pulp, and spray drying the litchi pulp to obtain the litchi powder.

3. The preparation method according to claim 2, characterized in that The variety of the litchi is selected from at least one of Baila, Baitangpeng, Feizishao, Heiye and Jizuili.

4. The preparation method according to claim 2, characterized in that The drying aid comprises at least one of maltodextrin, concentrated whey protein, gum arabic and soy protein.

5. The preparation method according to claim 2, characterized in that The added amount of the drying aid is 15% to 20% of the mass of the litchi pulp.

6. The preparation method according to claim 1, characterized in that The emulsifier includes at least one of soybean lecithin, gum arabic, gelatin, sodium carboxymethyl cellulose and sodium alginate.

7. The preparation method according to claim 1, characterized in that The whey protein concentrate includes at least one of WPC80, WPC35 and WPC90.

8. The preparation method according to claim 1, characterized in that The soy protein isolate and the whey protein concentrate are passed through a 70-90 mesh sieve before mixing; And / or, the xylitol is passed through a 90-110 mesh sieve before mixing.

9. Lychee-flavored protein powder containing γ-aminobutyric acid prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the preparation method according to any one of claims 1 to 8 in any one of (1) to (4): (1) preparing products that help improve sleep; (2) preparing products that help control body fat; (3) preparing products that help enhance immunity; (4) Prepare products that help maintain healthy blood pressure levels.

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