Method for simultaneously improving water and oil holding capacity of melon seed protein

Abstract

The present application belongs to the technical field of deep processing of melon seeds, and particularly relates to a method for simultaneously improving water holding capacity and oil holding capacity of melon seed protein. The method for simultaneously improving water holding capacity and oil holding capacity of melon seed protein comprises the following steps: (1) preparing melon seed powder, (2) extracting melon seed protein, (3) pH shift treatment of melon seed protein, (4) ultrasonic treatment of the melon seed protein solution after pH shift treatment, and (5) freeze-drying. The melon seed protein is treated by using pH shift combined with ultrasonic treatment, and the water holding capacity and oil holding capacity of the melon seed protein are simultaneously improved. Compared with untreated melon seed protein, the water holding capacity of the melon seed protein is increased by 45.18%, and the oil holding capacity is increased by 59.61%, so that the melon seed protein can be effectively utilized in the preparation of various foods, and the added value of the melon seed protein is greatly increased.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of deep processing of melon seeds, and particularly relates to a method for simultaneously improving water holding capacity and oil holding capacity of melon seed protein. BACKGROUND

[0002] Melon seeds are the seeds of melons. Research shows that melon seeds contain 30% of protein, and the types of amino acids are complete, among which the content of lysine is the highest, and the content of sulfur-containing amino acids is the second, so melon seeds are a high-quality plant protein source. In China, melons are mainly eaten in the form of fresh fruits or juice, and melon seeds are mostly discarded, so the rich nutrients in melon seeds cannot be effectively utilized. Meanwhile, although there are many studies on melons in China, there are few studies on the extraction and functionality of melon seed protein. The melon seed protein extracted from melon seeds has high nutritional value and protein efficiency ratio, and can be used as a new source of animal protein, so it has a broad prospect in the field of food processing.

[0003] The water holding capacity and oil holding capacity of protein are important characteristics and quality control indexes in the food processing process of cakes, meat products, bread, ice cream and the like. For flavor foods, the oil holding capacity of protein can improve the absorption and retention capacity of foods to fat, and improve the palatability and flavor of foods. The water holding capacity of protein reflects the binding capacity of protein to water and the compactness of gel network structure, and directly affects the tenderness and juiciness of foods. However, the water holding capacity and oil holding capacity of directly extracted melon seed protein are low.

[0004] Generally, because the oil holding capacity is high, the hydrophobicity will be correspondingly enhanced, so the water holding capacity and oil holding capacity of protein are difficult to be simultaneously improved. Through retrieval, there are few literature reports about the improvement of the water holding capacity and oil holding capacity of melon seed protein. Therefore, if the water holding capacity and oil holding capacity of melon seed protein can be simultaneously improved as much as possible, and a melon seed protein with high water holding capacity and oil holding capacity is provided, the application of melon seed protein in food will be more extensive, and the economic value of melon seeds will be improved. SUMMARY

[0005] In order to solve the above technical problems, the application provides a method for improving the water holding capacity and oil holding capacity of melon seed protein, which uses pH shift combined with ultrasonic treatment to process melon seed protein, so as to simultaneously improve the water holding capacity and oil holding capacity of melon seed protein, and make it better applied in food processing.

[0006] In order to achieve the above purpose, the technical scheme of the application is as follows:

[0007] In the first aspect of the application, a method for simultaneously improving the water holding capacity and oil holding capacity of melon seed protein is provided, and the method comprises the following steps:

[0008] (1) Preparation of melon seed powder: the melon seed is peeled and made into powder, the powder is removed of melon seed oil, dried, ground and sieved for use;

[0009] (2) Extraction of melon seed protein: the melon seed powder obtained in step (1) is treated by alkali dissolution and acid precipitation to extract melon seed protein, and the melon seed protein powder is obtained by drying;

[0010] (3) pH shift treatment of melon seed protein: the melon seed protein powder obtained in step (2) is prepared into a melon seed protein solution with deionized water, the pH of the protein solution is adjusted with 1 mol / L NaOH, and the acid-base shifted melon seed protein is obtained by standing and adjusting back to neutral;

[0011] (4) Ultrasonic treatment of the pH shifted melon seed protein solution: the acid-base shifted melon seed protein in step (3) is subjected to ultrasonic treatment;

[0012] (5) Freeze-drying: the melon seed protein subjected to ultrasonic treatment in step (4) is freeze-dried to obtain the melon seed protein subjected to pH shift and ultrasonic treatment.

[0013] Preferably, the powder obtained in step (1) is sieved through an 80-mesh sieve, and n-hexane is added for Soxhlet extraction to remove melon seed oil;

[0014] Preferably, the alkali dissolution and acid precipitation method in step (2) specifically comprises the following steps: the melon seed in step (1) is mixed with deionized water at a mass ratio of 1:60, the pH of the slurry is adjusted to 10 with 1 mol / L NaOH, the slurry is extracted on a shaking table at 40°C for 2 h, the supernatant is obtained by centrifugation at 4000 rpm, the pH is adjusted to 4.3 with 1 mol / L HCl, the supernatant is discarded after centrifugation at 8000 rpm for 20 min, and the melon seed protein precipitate is obtained. The pH of the protein precipitate is adjusted to 7.0 with 1 mol / L NaOH, and the melon seed protein powder is obtained by freeze-drying.

[0015] Preferably, in step (3), the pH is adjusted to 9-11, 1 mol / L HCl is added to adjust back to neutral after standing for 1 h; more preferably, the pH is adjusted to 11.

[0016] Preferably, in step (4), the ultrasonic treatment is performed at an ultrasonic power of 300-600 W for 10-20 min in an ice water bath; more preferably, the ultrasonic power is 450 W, and the ice water bath treatment is performed for 15 min.

[0017] In the second aspect of the present application, the high water and oil holding melon seed protein prepared by the above method is used in the preparation of food.

[0018] The present application has the following advantages:

[0019] (1) The present application uses pH shift and ultrasonic combination, first uses pH alkali shift to treat the melon seed protein, then uses ultrasonic to treat the melon seed protein after pH alkali shift, so that the water holding capacity and oil holding capacity of melon seed protein are improved, after treatment, the water holding capacity of melon seed protein can reach 3.972g·g -1 , the oil holding capacity can reach 5.015g·g -1 , compared with untreated melon seed protein, its water holding capacity is increased by 45.18%, and the oil holding capacity is increased by 59.61%.

[0020] (2) The melon seed protein prepared by the method of the present application has high water holding capacity and high oil holding capacity, and can be effectively used in the preparation of various foods, greatly increasing the added value of melon seed protein. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The water holding capacity and oil holding capacity of melon seed protein after pH acid-base shift combined with ultrasonic treatment;

[0022] Figure 2 It is a flow chart of experimental scheme. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the present application, the present application will be further described in conjunction with specific embodiments.

[0024] Example 1

[0025] A method for simultaneously improving the water holding capacity and oil holding capacity of melon seed protein, the method comprising the following steps:

[0026] (1) Preparation of melon seed powder: after peeling, the melon seed is ground into powder with a grinder, the powder is extracted with n-hexane to remove oil, and the remaining powder is dried in an oven, ground and sieved through an 80 mesh sieve for use;

[0027] (2) Extraction of melon seed protein: defatted melon seed is mixed with deionized water at a mass ratio of 1:60, the pH of the solution is adjusted to 10 with 1mol / L NaOH, and the solution is extracted at 40℃ for 2h, then centrifuged at 4000rpm to obtain the supernatant, the pH is adjusted to 4.3 with 1mol / L HCl, and after standing for 20min, the supernatant is discarded by centrifugation at 8000rpm, and the protein precipitate is obtained, the pH of the protein precipitate is adjusted to 7.0, and the freeze-dried melon seed protein powder is obtained;

[0028] (3) pH shift treatment of melon seed protein: the melon seed protein powder is prepared into a melon seed protein solution with deionized water, the pH of the solution is adjusted to 9 with 1mol / L NaOH, and after standing for 1h, 1mol / L HCl is added to adjust the pH to neutral;

[0029] (4) Ultrasonic treatment of the pH-shifted melon seed protein solution: under the condition of ice water bath, the pH-shifted melon seed protein solution was treated by ultrasonic with the power of 450 W for 15 min;

[0030] (5) Freeze-drying: the melon seed protein treated by ultrasonic in (4) was freeze-dried to obtain the melon seed protein treated by pH shift combined with ultrasonic.

[0031] Example 2

[0032] The difference from Example 1 is that the pH of the slurry is adjusted to 10 in step (3).

[0033] Example 3

[0034] The difference from Example 1 is that the ultrasonic treatment in step (4) is for 10 min.

[0035] Example 4

[0036] The difference from Example 1 is that the ultrasonic treatment in step (4) is for 20 min.

[0037] Example 5

[0038] The difference from Example 1 is that the ultrasonic power in step (4) is 300 W.

[0039] Example 6

[0040] The difference from Example 1 is that the ultrasonic power in step (4) is 600 W.

[0041] Comparative Example 1

[0042] The difference from Example 1 is that the melon seed protein is not subjected to pH shift treatment.

[0043] Comparative Example 2

[0044] The difference from Example 1 is that the melon seed protein is not subjected to ultrasonic treatment.

[0045] Comparative Example 3

[0046] The difference from Example 1 is that the melon seed protein is not subjected to pH shift and ultrasonic treatment.

[0047] Comparative Example 4

[0048] The difference from Example 1 is that the pH of the slurry is adjusted to 8 in step (3).

[0049] Comparative Example 5

[0050] The difference from Example 1 is that the pH of the slurry is adjusted to 11 in step (3).

[0051] Comparative Example 6

[0052] The difference from Example 1 is that the ultrasonic treatment power in step (4) is 150 W.

[0053] Comparative Example 7

[0054] The difference from Example 1 is that the ultrasonic treatment power in step (4) is 750 W.

[0055] Comparative Example 8

[0056] The difference from Example 1 is that the ultrasonic treatment time in step (4) is 5 min.

[0057] Comparative Example 9

[0058] The difference from Example 1 is that the ultrasonic treatment time in step (4) is 25 min.

[0059] Test Example

[0060] The water and oil holding capacities of the melon seed proteins of the examples and comparative examples were determined, and the results are shown in Table 1 and Figure 1

[0061] Determination Method:

[0062] 0.05 g of melon seed protein was weighed into a 5 mL centrifuge tube, and the weight was recorded as W1. 2 mL of deionized water / soybean oil was added, and the mixture was vortexed for 5 min to mix evenly. After standing for 1.0 h, the mixture was centrifuged at 8000 rpm for 10 min, and the supernatant was removed. The residual water and oil droplets on the wall of the centrifuge tube were absorbed with filter paper, and then the weight was recorded as W2. The water and oil holding capacities of the melon seed protein were calculated according to formula (3):

[0063]

[0064] In the formula, W0 is the mass of the melon seed protein / g; W1 is the mass of the centrifuge tube and protein / g; and W2 is the mass of the centrifuge tube and protein after removal of the supernatant / g.

[0065] Table 1 Water and oil holding capacities of melon seed proteins treated in different ways

[0066] Item Water holding capacity / g g -1 ]] Oil holding capacity / g g -1 ]] Example 1 3.972 5.015 Example 2 3.197 4.597 Example 3 3.243 4.806 Example 4 3.488 4.505 Example 5 3.367 4.295 Example 6 3.263 4.477 Comparative Example 1 3.186 3.974 Comparative Example 2 2.924 3.761 Comparative Example 3 2.736 3.142 Comparative Example 4 3.096 3.962 Comparative Example 5 3.057 4.523 Comparative Example 6 3.247 4.067 Comparative Example 7 3.246 3.842 Comparative Example 8 2.850 4.217 Comparative Example 9 3.127 3.986

[0067] ​According to Table 1, when the ultrasonic power is 450 W, the treatment time is 15 min, and the pH alkaline offset is 9, the water holding capacity and oil holding capacity of the melon seed protein are significantly improved, which are 3.972 g.g-1 and 5.015 g.g-1, respectively, compared with the untreated melon seed protein (Comparative Example 3), the water holding capacity is increased by 45.18%, and the oil holding capacity is increased by 59.61%; compared with the melon seed protein subjected to pH alkaline offset only, the water holding capacity is increased by 35.84%, and the oil holding capacity is increased by 33.34%; compared with the melon seed protein subjected to ultrasonic treatment only, the water holding capacity is increased by 24.67%, and the oil holding capacity is increased by 20.76%; it can be seen that the pH offset combined with ultrasonic treatment of the melon seed protein has a synergistic effect on the water holding capacity and oil holding capacity. The pH value has a certain effect on the water holding capacity and oil holding capacity of the melon seed protein, when the pH value is 7-9, the water holding capacity and oil holding capacity of the melon seed protein increase with the increase of the offset pH value, but when the pH value is further increased to more than 9, the water holding capacity and oil holding capacity of the melon seed protein decrease with the increase of the offset pH value; at the same time, the power of ultrasonic also has a certain effect on the water holding capacity and oil holding capacity of the melon seed protein, when the ultrasonic power is less than 450 W, the water holding capacity and oil holding capacity of the melon seed protein increase with the increase of the ultrasonic power, but when the ultrasonic power is greater than 450 W, the water holding capacity and oil holding capacity of the melon seed protein decrease with the increase of the ultrasonic power; it can be seen that only appropriate pH value and ultrasonic power can maximize the simultaneous improvement of the oil holding capacity and water holding capacity of the melon seed protein. That is, each step of the method of the application is indispensable and plays a synergistic role in simultaneously improving the water holding capacity and oil holding capacity of the melon seed protein.

Claims

1. A method for simultaneously improving the water and oil holding capacity of melon seed protein, characterized in that, The method comprises the following steps: (1) Preparation of melon seed powder: after the melon seeds are peeled, the powder is prepared by a grinder, the powder is extracted by n-hexane to remove melon seed oil, and the remaining powder is dried in an oven, ground and sieved through an 80-mesh sieve for use; (2) Extraction of melon seed protein: the defatted melon seeds are mixed with deionized water at a mass ratio of 1:60, the pH of the material solution is adjusted to 10 by 1 mol / L NaOH, and the solution is extracted by a shaking table at 40 DEG C for 2 h, and the supernatant is obtained by centrifugation at 4000 rpm; the pH is adjusted to 4.3 by 1 mol / L HCl, and the supernatant is discarded after centrifugation at 8000 rpm for 20 min; the pH of the protein precipitate is adjusted to 7.0, and the melon seed protein powder is obtained by freeze-drying; (3) pH shift treatment of melon seed protein: the melon seed protein powder is prepared into a melon seed protein solution with deionized water, the pH of the material solution is adjusted to 9 by 1 mol / L NaOH, and the solution is adjusted to neutral by adding 1 mol / L HCl after standing for 1 h; (4) Ultrasonic treatment of the melon seed protein solution after pH shift treatment: under the condition of ice water bath, the solution is treated by ultrasonic waves with a power of 450 W for 15 min; (5) Freeze-drying: the melon seed protein after ultrasonic treatment in (4) is freeze-dried to obtain the melon seed protein treated by pH shift and ultrasonic waves.

2. Application of the high water-holding and oil-holding melon seed protein prepared by the method of claim 1 in the preparation of food.

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