Chinese chestnut freshness locking method based on moisture migration and application thereof

Abstract

The invention discloses a chestnut freshness locking method based on moisture migration and application thereof, and belongs to the technical field of chestnut processing. The freshness locking method for the Chinese chestnuts comprises the step of sequentially performing quick-freezing stepped treatment on the Chinese chestnuts at 4 DEG C, 18 DEG C below zero, 45 DEG C below zero and 80 DEG C below zero in different time periods. The quick-freezing stepped treatment time at 4 DEG C,-18 DEG C,-45 DEG C and-80 DEG C is 15 minutes, 15 minutes, 15 minutes and 30 minutes respectively. Before the quick-freezing treatment, the Chinese chestnuts are subjected to curing treatment. The curing treatment comprises steaming treatment and boiling treatment. According to the freshness locking method for the Chinese chestnuts, the distribution state of free water in the Chinese chestnuts is reserved to the maximum extent on the basis of water distribution and migration in different treatment processes, and the good soft and glutinous taste of the Chinese chestnuts can be kept whether the Chinese chestnuts are directly eaten after being unfrozen or eaten after being baked again. According to the Chinese chestnut freshness locking method based on moisture migration, theoretical basis and technical support are provided for freezing and freshness preservation of Chinese chestnuts.

Description

Technical Field

[0001] The invention relates to the field of chestnut processing, and in particular to a chestnut freshness-locking method based on moisture migration and application thereof. Background Art

[0002] Chestnut (Castanea mollissima) is a seasonal nut native to China with a long history of cultivation. Widely cultivated as an important economic crop, chestnut is highly regarded for its rich nutritional value. Chestnut contains a variety of nutrients that are beneficial to the human body, mainly including bioactive compounds such as flavonoids, polyphenols, etc. These substances have multiple biological activities such as antioxidant and anti-inflammatory, and have a positive effect on human health. In addition, chestnut is also rich in vitamin C, B vitamins, minerals (such as potassium, magnesium, iron), etc., and is a food with extremely high nutritional value. Therefore, Chinese chestnuts have strong market competitiveness in the international market and are deeply loved by consumers.

[0003] Chestnut is a seasonal nut with high nutritional value and unique flavor. It is also a food that can be used as both medicine and food. However, chestnuts are highly time-sensitive and their quality deteriorates quickly, especially under normal storage conditions. Over time, the moisture content inside the chestnuts will gradually decrease, causing the chestnut kernels to become hard and dry, seriously affecting their taste and eating experience. At present, there are few reports on the maintenance of chestnut quality through water migration. Therefore, it is of great significance to solve the problem of chestnut kernels becoming hard and dry. Only by effectively controlling the water loss of chestnuts can their original taste and texture be maintained, thereby improving consumer satisfaction. High-quality chestnut products can better meet market demand and enhance the competitiveness of Chinese chestnuts in the international market. Therefore, solving the problem of chestnut kernels becoming hard and dry is of great significance for improving the quality of chestnuts, extending their shelf life, and enhancing their market competitiveness. Summary of the invention

[0004] The purpose of the present invention is to provide a chestnut fresh-keeping method based on moisture migration and its application, so as to solve the problems existing in the above-mentioned prior art. The present invention uses a low-field nuclear magnetic resonance method and texture to collect the relaxation time and hardness of chestnut samples, and uses a large number of chestnut samples as model samples to repeatedly collect information on multiple chestnut samples, explore the optimal conditions for chestnut preservation, and apply it to the fresh-keeping analysis of chestnut quality, so as to solve the problem that chestnuts become dry and hard after long storage time. Experiments have proved that the method of the present invention can be used to preserve chestnuts, so that chestnuts can be better preserved.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] Technical Solution 1: A method for locking in the freshness of chestnuts based on moisture migration, comprising the steps of subjecting the chestnuts to a step-by-step quick-freezing treatment at 4°C, -18°C, -45°C and -80°C in different time periods.

[0007] Furthermore, the time for the 4°C, -18°C, -45°C and -80°C quick freezing step treatments is 15 minutes, 15 minutes, 15 minutes and 30 minutes respectively. The treatment process is based on the characteristics of vitrification freezing and water migration, and the water distribution is controlled according to different times to achieve the best effect.

[0008] Furthermore, before the quick freezing process, the chestnuts are first subjected to a ripening process.

[0009] Furthermore, the aging process includes steaming and boiling.

[0010] Furthermore, the aging treatment time is 20 minutes.

[0011] Furthermore, the chestnuts are free from diseases and insect pests.

[0012] Technical solution 2: Application of the chestnut freshness-locking method in chestnut processing or chestnut storage.

[0013] The embodiment of the present invention specifically provides a method for preserving and locking the freshness of chestnuts, comprising the following steps:

[0014] S1: Select chestnuts of moderate size and free of pests and diseases, and steam and boil them until they are ripe, and then measure the texture and water migration indicators;

[0015] S2: Using a variety of freezing methods, the chestnuts that have undergone heat treatment are frozen at different temperatures according to time periods, and the texture and water migration of the chestnuts are measured;

[0016] S3: Thawing the quick-frozen chestnuts at room temperature, then thawing and baking them, and then testing the texture and water migration indicators;

[0017] S4: Summarize the data obtained and find out the conditions suitable for locking in the freshness of chestnuts.

[0018] The chestnut sample detected by the low-field nuclear magnetic resonance analysis method for non-destructive detection of chestnuts provided by the present invention is an unshelled chestnut. Low-field nuclear magnetic resonance technology is a detection technology that can analyze the state and distribution of water by measuring relaxation characteristics. This method has the advantages of fast detection speed, clear and visualized data, etc., and can be used to analyze food quality and processing characteristics in combination with other indicators.

[0019] Furthermore, in step S1, the chestnuts are pretreated by heat processing, the hardness of the chestnut samples after heat processing is measured by a texture analyzer, and the water migration of the chestnuts is measured by low-field nuclear magnetic resonance and image information is collected.

[0020] Furthermore, the texture analyzer parameters used are: the distance from the disk probe to the zero point is 30 mm, the disk diameter is 50 mm, the pressing speed is 60 mm / min, the test pressure is 0.5 N, and the test depth (deformation variable) is 20%; the low-field nuclear magnetic resonance CPMG sequence acquisition parameters are: radio frequency 21 MHz, frequency offset is 48733.03 Hz, 90-degree pulse width is 9.40 us, number of sampling points is 2048, front gear position is 0, waiting time is 2000 ms, 180-degree pulse width is 12.24 us, sampling frequency is 200 kHz, radio frequency delay is 0.2 ms, digital gain is 3, analog gain is 20, and accumulation times is 4; each treatment is repeated 3 times, and the iteration times are selected to be hundreds of thousands for data inversion.

[0021] Furthermore, the characteristic relaxation time of the chestnut sample is: the relaxation time of bound water of the chestnut sample is T21 and T22, the relaxation time of non-flowing water of the chestnut sample is A21 and A22, and the relaxation time of free water of the chestnut sample is S21 and S22; the hardness of the sample is N1 and N2.

[0022] Furthermore, the optimal conditions for fresh-keeping and freezing chestnuts were explored based on the relaxation time of free water in chestnut samples and the hardness of chestnut samples. The relaxation time of free water in chestnut samples was S21 and S22, and the hardness was N1 and N2.

[0023] Furthermore, based on the analysis and comparison of the moisture migration data and hardness data of the chestnut samples, the conditions used for the chestnut samples with higher free water content and lower hardness were the optimal conditions for chestnut preservation and freezing.

[0024] In addition, the chestnut preservation and freshness-locking method provided by the present invention can be applied to maintaining the quality of chestnuts.

[0025] The present invention discloses the following technical effects:

[0026] The chestnut fresh-keeping and freezing method provided by the present invention is used for chestnuts with shells. The chestnuts after two different heat treatments are subjected to different freezing treatments, and then thawed and baked. By comparing the hardness and free water content of the thawed and baked chestnut samples, the conditions for the chestnut sample to have better quality are explored, and the purpose of maintaining the quality of the chestnut is achieved. The thawed chestnuts can not only be eaten cold, but also can be eaten hot after baking, one chestnut can be eaten in two ways, which greatly solves the problem of chestnut preservation and enables fresh chestnuts with shells to be supplied year-round. The chestnut fresh-keeping method provided by the present invention is based on the distribution and migration of water in different treatment processes, and the distribution state of bound water in the chestnut is retained to the maximum extent, so that the chestnut can maintain a good soft and glutinous taste whether it is eaten directly after thawing or baked. The chestnut fresh-keeping method provided by the present invention is quick-frozen and fresh-keeping after a series of pre-treatments, and the chestnut can obtain a good chewiness and hardness quality preservation, so that the quality loss is minimized, the steps are simple, and the operation is fast. The method can directly process the chestnuts with shells without shelling the chestnuts. In summary, in order to solve the problem of water loss and hardening of chestnut flesh during chestnut processing, the chestnut freshness-locking method based on water migration provided by the present invention provides a theoretical basis and technical support for the frozen preservation of chestnuts. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 The diagram shows the water migration changes of steamed chestnuts at 4℃, -18℃, -45℃ and -80℃ freezing methods;

[0029] Figure 2 The diagram shows the moisture distribution changes of steamed chestnuts at 4℃, -18℃, -45℃ and -80℃ freezing methods;

[0030] Figure 3 The hardness change diagram of steamed chestnuts at 4℃, -18℃, -45℃ and -80℃ freezing methods;

[0031] Figure 4 The diagram shows the changes in water migration of boiled chestnuts at 4℃, -18℃, -45℃ and -80℃ freezing methods;

[0032] Figure 5 The diagram shows the change of moisture distribution of chestnuts cooked at 4℃, -18℃, -45℃ and -80℃ freezing methods;

[0033] Figure 6The hardness change diagram of chestnuts cooked at 4℃, -18℃, -45℃ and -80℃ freezing methods;

[0034] Figure 7 The diagram shows the changes in water migration of chestnuts steamed at 4°C, -45°C and frozen with liquid nitrogen;

[0035] Figure 8 The diagram shows the change of moisture distribution of chestnuts steamed at 4℃, -45℃ and liquid nitrogen freezing method;

[0036] Fig. 9 The hardness change diagram of chestnuts steamed at 4℃, -45℃ and liquid nitrogen freezing method;

[0037] Fig.10 The diagram shows the changes in water migration of chestnuts cooked at 4°C, -45°C and liquid nitrogen freezing.

[0038] Fig.11 The diagram shows the changes in moisture distribution of chestnuts cooked at 4°C, -45°C and liquid nitrogen freezing methods;

[0039] Fig.12 The hardness change diagram of chestnuts cooked at 4℃, -45℃ and liquid nitrogen freezing method;

[0040] Fig.13 The diagram shows the change of water migration of steamed chestnuts at 4℃, -45℃ and -80℃ freezing methods;

[0041] Fig.14 The diagram shows the moisture distribution changes of steamed chestnuts at 4℃, -45℃ and -80℃ freezing methods;

[0042] Fig.15 The hardness change diagram of steamed chestnuts at 4℃, -45℃ and -80℃ freezing methods;

[0043] Fig.16 The diagram shows the change of water migration of chestnuts cooked at 4℃, -45℃ and -80℃ freezing methods;

[0044] Fig.17 The diagram of the moisture distribution change of chestnuts cooked at 4℃, -45℃ and -80℃ freezing methods;

[0045] Fig.18 The hardness change diagram of chestnuts cooked at 4℃, -45℃ and -80℃ freezing methods;

[0046] Fig.19 The diagram shows the changes in water migration of chestnuts steamed at 4°C, -45°C and frozen with liquid nitrogen;

[0047] Fig. 20 The diagram shows the change of moisture distribution of chestnuts steamed at 4℃, -45℃ and liquid nitrogen freezing method;

[0048] Fig.21 The hardness change diagram of chestnuts steamed at 4℃, -45℃ and liquid nitrogen freezing method;

[0049] Fig. 22 The diagram shows the changes in water migration of chestnuts cooked at 4°C, -45°C and liquid nitrogen freezing.

[0050] Fig.23 The diagram shows the changes in moisture distribution of chestnuts cooked at 4°C, -45°C and liquid nitrogen freezing methods;

[0051] Fig.24 The hardness change diagram of chestnuts cooked at 4℃, -45℃ and liquid nitrogen freezing method;

[0052] Fig.25 This is a diagram showing the changes in water migration after chestnuts were frozen in three conventional ways;

[0053] Fig.26 This is a diagram showing the changes in moisture distribution of chestnuts after being frozen in three conventional ways;

[0054] Fig. 27 This is a graph showing the hardness changes of chestnuts after being frozen in three conventional ways, among which the -196℃ group is the liquid nitrogen group. DETAILED DESCRIPTION

[0055] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0056] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0057] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0058] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0059] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0060] Example 1

[0061] 1 Experimental methods and parameters

[0062] The parameters of the texture analyzer are as follows: the distance from the disk probe to the zero point is 30 mm, the disk diameter is 50 mm, the pressing speed is 60 mm / min, the test pressure is 0.5 N, and the test depth (deformation variable) is 20%; the acquisition parameters of the low-field nuclear magnetic resonance CPMG sequence are as follows: radio frequency 21 MHz, frequency offset 48733.03 Hz, 90-degree pulse width 9.40 us, number of sampling points 2048, front gear 0, waiting time 2000 ms, 180-degree pulse width 12.24 us, sampling frequency 200 kHz, radio frequency delay 0.2 ms, digital gain 3, analog gain 20, and accumulation times 4; each treatment is repeated 3 times, and the iteration times are selected to be hundreds of thousands for data inversion.

[0063] 2. Hot working

[0064] Cut the chestnuts and divide them into two groups. After the water boils, steam and boil them for 20 minutes respectively. After the chestnuts are processed, the hardness and water migration are measured. This is the first stage.

[0065] 3. Quick freezing

[0066] The steamed and boiled chestnuts after heat treatment were divided into 4 groups, a total of 8 groups, namely S1, S2, S3, S4 and Z1, Z2, Z3, Z4. The chestnuts in group S were steamed, and the chestnuts in group Z were boiled. The chestnut samples of group S1 and group Z1 were treated with 4℃, -18℃, -45℃ and -80℃ freezing methods, with treatment times of 15min, 15min, 15min and 30min respectively; the chestnut samples of group S2 and group Z2 were treated with 4℃, -18℃, -45℃ and liquid nitrogen freezing methods, with treatment times of 15min, 15min, 15min and 10s respectively; the chestnut samples of group S3 and group Z3 were treated with 4℃, -45℃ and -80℃ freezing methods, with treatment times of 15min, 15min and 30min respectively; the chestnut samples of group S4 and group Z4 were treated with 4℃, -45℃ and liquid nitrogen freezing methods, with treatment times of 15min, 15min and 10s respectively; when the central temperature of the samples reached -18℃, they were taken out and placed in a refrigerator for frozen storage; the hardness and moisture migration of the thawed chestnut samples were measured, which was the second stage.

[0067] 4. Grill

[0068] The thawed chestnuts were baked in an oven at 180°C for 15 minutes, and then the texture and moisture migration indicators were measured. This is the third stage.

[0069] 5 Data processing

[0070] After analyzing the data of chestnut samples at various stages, it was found that the chestnuts had the best quality after being steamed and frozen at 4℃, -18℃, -45℃ and -80℃ in sequence. After subsequent baking, the hardness was the lowest, the free water moisture was higher, and the taste was better.

[0071] Example Effect of 24°C, -18°C, -45°C and -80°C Freezing Methods on the Quality Preservation of Steamed Chestnuts

[0072] Add water to the steamer, and when the water boils, put the opened chestnuts into the steamer and steam for 20 minutes, then measure the chestnut hardness and moisture migration; then put the steamed chestnuts in a 4℃ refrigerator for 15 minutes, then transfer them to a -18℃ freezer for 15 minutes, then transfer them to a -45℃ quick freezer for 15 minutes, and finally transfer them to a -80℃ refrigerator for 30 minutes, take them out, thaw them, and measure the chestnut hardness and moisture migration; put the thawed chestnuts in an oven and bake them at 180℃ for 15 minutes, take them out, and measure the chestnut moisture migration and hardness.

[0073] like Figure 1-Figure 3As shown, the free water content of the sample gradually increases in the first and second stages, and the bound water gradually decreases. A part of the increase in free water is the entry of external water during thermal processing, and the other part is the conversion of bound water into free water during freezing and thawing. The free water content of this embodiment in the second and third stages is the highest among the 8 embodiments, and the taste is better; the hardness of the chestnut sample shows a trend of first decreasing, then decreasing, and then increasing, and the texture just reaches the best.

[0074] Example Effect of 24°C, -18°C, -45°C and -80°C Freezing Methods on the Quality Preservation of Cooked Chestnuts

[0075] Add water to a cooking pot, put the opened chestnuts into the cooking pot after the water boils, and cook for 20 minutes, then measure the chestnut hardness and moisture migration; then put the cooked chestnuts in a 4℃ refrigerator for 15 minutes, then transfer to a -18℃ freezer for 15 minutes, then transfer to a -45℃ quick freezer for 15 minutes, then transfer to a -80℃ refrigerator for 30 minutes, take out, thaw, and measure the chestnut hardness and moisture migration; put the thawed chestnuts in an oven at 180℃ for 15 minutes, take out, and measure the chestnut moisture migration and hardness.

[0076] like Figure 4-Figure 6 As shown, the free water content of the chestnut sample also shows a gradually increasing trend in the early stage, but the free water content decreases greatly after roasting, and the hardness shows a trend of first decreasing, then decreasing, and then increasing, but the increase in the later stage is smaller than that in Example 1, and the texture is relatively soft and rotten.

[0077] Example 3 Effects of 4°C, -18°C, -45°C and liquid nitrogen freezing methods on the quality maintenance of steamed chestnuts

[0078] Add water to the steamer, put the opened chestnuts into the steamer after the water boils, and steam for 20 minutes, then measure the chestnut hardness and moisture migration; then put the steamed chestnuts in a 4℃ refrigerator for 15 minutes, then transfer them to a -18℃ freezer for 15 minutes, then transfer them to a -45℃ quick freezer for 15 minutes, then treat them with liquid nitrogen for 10 seconds, take them out, thaw them, and measure the chestnut hardness and moisture migration; put the thawed chestnuts in an oven and bake them at 180℃ for 15 minutes, take them out, and measure the chestnut moisture migration and hardness.

[0079] like Figure 7-Figure 9 As shown, the free water content of chestnut samples showed an increasing trend in the first and second stages, but the peak value was greatly reduced compared with the -80℃ freezing method, the hardness was also relatively high, and the texture was poor.

[0080] Example 4 Effects of 4°C, -18°C, -45°C and Liquid Nitrogen Freezing Methods on the Quality Preservation of Cooked Chestnuts

[0081] Add water to a cooking pot, put the opened chestnuts into the pot after the water boils, and cook for 20 minutes, then measure the chestnut hardness and moisture migration; then put the cooked chestnuts in a 4℃ refrigerator for 15 minutes, then transfer them to a -18℃ freezer for 15 minutes, then transfer them to a -45℃ quick freezer for 15 minutes, then treat them with liquid nitrogen for 10 seconds, take them out, thaw them, and measure the chestnut hardness and moisture migration; put the thawed chestnuts in an oven and bake them at 180℃ for 15 minutes, take them out, and measure the chestnut moisture migration and hardness.

[0082] like Figure 10-12 As shown, the free water content and hardness change trends of the chestnut samples are the same as those in Example 2, but the hardness shows a trend of first decreasing and then increasing. However, the hardness of boiled chestnuts is obviously smaller than that of steamed chestnuts.

[0083] Example 5 Effect of 4°C, -45°C and -80°C Freezing Methods on the Quality Preservation of Steamed Chestnuts

[0084] Add water to the steamer, put the opened chestnuts into the steamer after the water boils, and steam for 20 minutes, then measure the chestnut hardness and moisture migration; then put the steamed chestnuts in a 4℃ refrigerator for 15 minutes, then transfer them to a -45℃ quick freezer for 15 minutes, then transfer them to a -80℃ refrigerator for 30 minutes, then take them out, thaw them, and measure the chestnut hardness and moisture migration; put the thawed chestnuts in an oven at 180℃ and bake them for 15 minutes, take them out, and measure the chestnut moisture migration and hardness.

[0085] like Figure 13-Figure 15 As shown, the free water content of the chestnut samples showed the same trend as in the previous examples, indicating that the steaming process can effectively increase the free water content of the chestnuts, but Example 5 was slightly insufficient in terms of hardness.

[0086] Example 6 Effect of 4°C, -45°C and -80°C Freezing Methods on the Quality Preservation of Cooked Chestnuts

[0087] Add water to a cooking pot, put the opened chestnuts into the pot after the water boils, and cook for 20 minutes, then measure the chestnut hardness and moisture migration; then put the cooked chestnuts in a 4℃ refrigerator for 15 minutes, then transfer them to a -45℃ quick freezer for 15 minutes, then transfer them to a -80℃ refrigerator for 30 minutes, then take them out, thaw them, and measure the chestnut hardness and moisture migration; put the thawed chestnuts in an oven at 180℃ and bake them for 15 minutes, take them out, and measure the chestnut moisture migration and hardness.

[0088] like Figure 16-18 As shown, the chestnut sample showed the same trend as Example 1, Example 2 and Example 5, with the content gradually increasing, but the highest peak texture was poor.

[0089] Example Effects of 74°C, -45°C and Liquid Nitrogen Freezing Methods on the Quality Preservation of Steamed Chestnuts

[0090] Add water to the steamer, put the opened chestnuts into the steamer after the water boils, and steam for 20 minutes, then measure the chestnut hardness and moisture migration; then put the steamed chestnuts in a 4℃ refrigerator for 15 minutes, then transfer them to a -45℃ quick freezer for 15 minutes, then treat them with liquid nitrogen for 10 seconds, then take them out and thaw them, and measure the chestnut hardness and moisture migration; put the thawed chestnuts in an oven and bake them at 180℃ for 15 minutes, take them out, and measure the chestnut moisture migration and hardness.

[0091] like Figure 19-21 As shown, the peak value of the free water content of the chestnut sample is at a lower level compared with other embodiments, the effect of liquid nitrogen treatment on the chestnut sample is poor, and the hardness of the chestnut sample is also relatively high.

[0092] Example 8 Effects of 4°C, -45°C and Liquid Nitrogen Freezing Methods on the Quality Preservation of Cooked Chestnuts

[0093] Add water to a cooking pot, put the opened chestnuts into the pot after the water boils, and cook for 20 minutes, then measure the chestnut hardness and moisture migration; then put the cooked chestnuts in a 4℃ refrigerator for 15 minutes, then transfer them to a -45℃ quick freezer for 15 minutes, then treat them with liquid nitrogen for 10 seconds, then take them out, thaw them, and measure the chestnut hardness and moisture migration; put the thawed chestnuts in an oven at 180℃ for 15 minutes, take them out, and measure the chestnut moisture migration and hardness.

[0094] like Figure 22-Figure 24 As shown, the chestnut sample has lower free water content and its texture is improved compared with Example 7.

[0095] Comparative Example Effects of 13 Conventional Quick-Freezing Methods on Chestnut Quality

[0096] Compared with Example 1, this comparative example differs only in the quick-freezing treatment of chestnuts:

[0097] Method 1: Place chestnuts in a -45℃ quick freezer for 30 minutes, take them out, thaw them, and measure the moisture migration and hardness of the chestnuts;

[0098] Method 2: Place the chestnuts in a -80℃ freezer for 1 hour, take them out, thaw them, and measure the water migration and hardness;

[0099] Method 3: Treat the chestnuts with liquid nitrogen for 25 seconds, take them out, thaw them, and measure the moisture migration and hardness.

[0100] like Figure 25-27As shown, the free water content of the chestnut samples obtained by the three conventional methods is generally lower than that of the embodiment, and the hardness is also relatively poor, and the method in Example 2 maintains the quality of the chestnut samples best.

[0101] Based on the above data, it can be concluded that chestnuts can maintain a better taste and texture by quick freezing at 4℃, -18℃, -45℃ and -80℃ after steaming. This can effectively solve the problem of chestnuts becoming dry and hard under normal storage, solve the problem of chestnuts' timeliness, and improve the economic benefits of chestnuts.

[0102] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for locking freshness of chestnuts based on water migration, characterized in that: The method comprises the steps of subjecting chestnuts to a step-by-step quick-freezing treatment at 4°C, -18°C, -45°C and -80°C in sequence in different time periods.

2. The method for preserving chestnut freshness according to claim 1, characterized in that: The time for the quick freezing step treatment at 4°C, -18°C, -45°C and -80°C is 15min, 15min, 15min and 30min respectively.

3. The method for locking in freshness of chestnuts according to claim 1, characterized in that: Before the quick freezing process, the chestnuts are first subjected to a ripening process.

4. The method for locking in freshness of chestnuts according to claim 3, characterized in that: The aging process includes steaming and boiling.

5. The method for locking in freshness of chestnuts according to claim 4, characterized in that: The aging treatment time is 20 minutes.

6. The method for preserving chestnut freshness according to claim 1, characterized in that: The chestnuts are free from diseases and insect pests.

7. Use of the chestnut freshness-locking method according to any one of claims 1 to 6 in chestnut processing or chestnut storage.

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