Dry combined low-oil puffed undaria pinnatifida leisure food and preparation method thereof

Abstract

The invention discloses a preparation method of dried low-oil puffed undaria pinnatifida snack food, which comprises the following steps: firstly, performing rinsing, soaking and surface air-drying treatment on salted undaria pinnatifida stems to remove salt and impurities; then, the treated undaria pinnatifida slices are subjected to vacuum drying, and the moisture content is reduced to 40-50%; then, quickly performing freezing treatment at-38 DEG C; then, performing low-temperature frying by adopting a vacuum frying process so as to retain active ingredients in the undaria pinnatifida to the maximum extent; and finally, the crispness and the taste of the product are further improved through freeze drying. The method effectively solves the problem of poor puffing effect caused by high moisture content and compact tissue structure in the puffing process of the undaria pinnatifida, and the produced undaria pinnatifida crisp chips have excellent taste, color and nutritional value, and have wide market application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of food, and in particular to a dry combined low-oil puffed wakame leisure food and a preparation method thereof. Background Art

[0002] As a fast-moving consumer product, snack foods are usually consumed in consumers' spare time, aiming to provide convenient enjoyment and satisfaction. With the improvement of people's awareness of healthy eating and sustainable consumption, consumers' requirements for the nutritional content, healthiness and environmental protection of food have gradually increased, which provides a broad market space for the development of new healthy and environmentally friendly puffed snack foods. However, the current market share of marine snack foods (such as fish, shrimp, crab, shellfish and seaweed, etc.) is still relatively low, only 2.7%, and most marine snack foods are still in the low-end market stage, failing to fully meet consumers' demand for high-quality, diversified and functional foods.

[0003] As a brown algae rich in polysaccharides, alginate and fucoxanthin, kelp has significant pharmacological effects, including enhancing immune function, anti-tumor, and lowering cholesterol. Its ingredients can effectively promote the expression of lymphocyte subsets and the secretion of T cell growth factors, thereby enhancing immunity. At the same time, alginate and fucoxanthin also help prevent cardiovascular diseases such as cerebral thrombosis, arteriosclerosis and hypertension. The high moisture content (75% to 95%) and compact tissue structure of kelp, especially the strong hydration capacity and gel properties of algin, bring challenges to its expansion process. Unlike terrestrial plants, the abundant alginate in kelp cannot provide a good skeleton for puffing, and it is difficult to achieve the ideal expansion effect during the puffing process. When heated, alginate forms a heat-stable gel instead of decomposing and softening, which hinders the evaporation of water. In addition, the dense gel structure inhibits the formation of a rigid network, and often forms a porous structure with a hard texture and uneven structure during the puffing process, resulting in the lack of ideal crispness and taste in the puffed food, making the existing technology have a poor puffing effect on kelp.

[0004] At present, the preparation process of puffed snack foods has been studied and applied to a certain extent. For example, patent CN118525913A discloses a production method for instant pumpkin crisps. The method includes the steps of washing, blanching, sugaring, vacuum frying and deoiling the pumpkin slices. Although vacuum frying can effectively control the absorption of oil, a longer frying time may lead to excessive oil absorption, thereby increasing the fat content and browning reaction of the food. Patent CN118947802A discloses a method for improving the crispness of vacuum low-temperature fried lotus root slices, which improves the crispness of fried lotus root slices by pre-treatment methods such as blanching, sugaring, and freezing, but the method does not control the moisture content of the lotus root slices before frying, which may lead to the problem of high oil content in the lotus root slices after frying. Patent CN202310023072.7 discloses a production method of instant mushroom crisps, which is produced by coating, desizing, hot oil shaping, deoiling, softening, and freeze drying. Although this method retains the flavor of mushrooms, due to the coating process, the dehydration of mushrooms inside the slurry is poor during frying. It is necessary to use freeze drying for a long time to further reduce the moisture content, and the energy consumption is large. Patent CN104473100A discloses a production process of leisure taro puffed crisps, including blanching, color protection, sugar dipping, blast drying, vacuum microwave drying and baking of taro blocks. The process is dried in multiple stages to finally obtain low-fat puffed taro crisps. However, similar puffing processes are not suitable for the production of kelp, mainly because the algin structure of kelp and its high water content make it difficult for conventional microwave drying and frying methods to meet the puffing requirements. Therefore, in view of the special properties of kelp, developing a production process that can effectively improve the puffing effect of kelp, improve the product taste, color, aroma and nutritional value has important technical significance and market potential. The existing puffed snack food production process mainly focuses on raw material processing, color protection and drying and frying, but for the special raw material of kelp, traditional puffing methods are difficult to achieve ideal effects. Therefore, it is necessary to study a new process to achieve the ideal puffing of kelp and meet consumers' demand for healthy and nutritious snack foods. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a dry combined low-oil puffed wakame snack food and a preparation method thereof, wherein the washed wakame is first vacuum dried to make its moisture content between 40% and 50%, and then vacuum fried and freeze-dried to prepare wakame chips. The wakame chips obtained by the method have a high crispness, and the quality of the finished product is significantly improved, providing good technical support for the development of high-quality wakame chips products.

[0006] To achieve the above object, the present invention first provides a method for preparing a dry combined low-oil puffed wakame leisure food, comprising the following steps:

[0007] S1. Cleaning and processing of raw materials: rinsing and draining the wakame stems and cutting them into wakame slices for later use;

[0008] S2, drying: placing the wakame slices obtained in step S1 in a vacuum drying device for dehydration;

[0009] S3, freezing: quickly placing the dried wakame slices in step S2 into a cold storage for freezing;

[0010] S4, vacuum frying: vacuum frying the frozen wakame slices in step S3;

[0011] S5, freeze drying: the fried wakame slices in step S4 are quickly placed into a freeze dryer, and subjected to primary freezing, sublimation drying, and secondary drying in sequence to obtain wakame crispy slices.

[0012] In one embodiment of the present invention, the preparation process of the kelp slices in step S1 is as follows: rinse the salted kelp stems without brown spots, odor, and in accordance with the "SC / T 3211-2019" standard to wash away the salt and impurities on the surface of the kelp stems. Then soak them in running water for 2-3 hours, with the flow rate maintained at 3-5 liters of water per kilogram of kelp per minute, so that they can fully absorb water and swell. Blow the treated kelp stems with a wind speed of 5m / s to remove the surface water. Select kelp stems with a stem width of 3.0-2.0cm, cut them into approximately square kelp slices for later use.

[0013] In one embodiment of the present invention, in step S2, when the kelp slices are vacuum dried, the drying temperature is 55-65° C., the vacuum degree is -0.8 bar, and the kelp slices are dried until the moisture content is reduced to 40-50%.

[0014] In one embodiment of the present invention, in step S3, the freezing temperature is -38 to -40°C, and the freezing time is 1 to 3 hours.

[0015] In one embodiment of the present invention, in step S4, the vacuum frying temperature is 95 to 105°C, the vacuum degree is -85 to -95kPa, and the frying time is 8 to 15 minutes. Furthermore, the timing starts when the vacuum degree reaches -85kPa, and the frying time is 10 minutes. Vacuum frying can quickly remove moisture at low temperatures, avoid nutritional losses caused by high-temperature frying, and reduce oil absorption. The vacuum is broken immediately after frying to prevent the re-condensation of water vapor from affecting crispness. In order to further remove excess oil, the fried kelp slices are centrifuged and deoiled at a speed of 1000rpm for 10 minutes to ensure that the surface oil content is reduced.

[0016] In one embodiment of the present invention, in step S5, the deoiled kelp slices obtained in step S4 are quickly transferred to a freeze dryer for freeze drying. The initial freezing temperature is set to -38 to -40°C, the initial freezing time is 1 to 2 hours, and the vacuum degree is controlled between 10 and 100 Pa. Then enter the sublimation stage, the sublimation temperature is -10 to -30°C, this stage removes the residual moisture in the kelp slices. After the sublimation stage, secondary drying is carried out at a temperature of 30°C to 40°C until the kelp slices reach constant weight. Freeze drying can effectively remove moisture and maintain the crisp structure and nutritional components of kelp to the greatest extent.

[0017] The invention also provides a kelp leisure food prepared according to the method.

[0018] Beneficial effects of the present invention:

[0019] (1) Through the processing technology of vacuum drying, freezing, vacuum low-temperature frying combined with freeze drying, a suitable structure is provided for the kelp, so that the kelp chips have a higher crispness. During the vacuum frying process, under the conditions of low temperature and low vacuum, the structure of the kelp slices remains intact, and they can be evenly expanded to form a fragile void structure, which enhances the crispness.

[0020] (2) Vacuum frying can be carried out at a lower temperature, avoiding the high temperature operation in conventional frying. The amount of fat absorption is significantly reduced, and the final product has a lower fat content, which is more in line with the modern consumer's demand for healthy food.

[0021] (3) The vacuum drying, low-temperature frying and freeze-drying processes adopted by the present invention can retain the vitamins, minerals and other active ingredients in the kelp to the greatest extent, so that the finished product has a higher nutritional value.

[0022] (4) By precisely controlling the temperature and time, the crispy texture of the wakame chips is ensured while maintaining their original wakame flavor without being affected by high temperature or frying.

[0023] (5) The dehydration method of vacuum drying combined with vacuum frying can shorten the drying cycle and improve production efficiency while maintaining the quality of kelp. This technical improvement helps to achieve a faster production cycle and reduce unit production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a comparison chart of the fracture distance of the puncture test of the kelp chips prepared in Examples 1 to 2 and Comparative Examples 1 to 5.

[0025] Figure 2 It is a comparison chart of the puncture rupture strength of the kelp chips prepared in Examples 1 to 2 and Comparative Examples 1 to 5 in the puncture test.

[0026] Figure 3 This is a comparison chart of the fracture distances of the puncture test of the kelp chips prepared in Example 1 and Examples 3-4.

[0027] Figure 4 This is a comparison chart of the puncture rupture strength of the kelp chips prepared in Example 1 and Examples 3-4 in the puncture test. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art.

[0029] Example 1

[0030] A dry combined low-oil puffed wakame snack food and a preparation method thereof, comprising the following steps:

[0031] (1) Rinse the salted wakame stems that are free of brown spots and odor and meet the "SC / T 3211-2019" standard to remove salt and impurities on the surface of the wakame stems. Then soak them in running water for 2 hours, with the flow rate maintained at 3 liters of water per kilogram of wakame per minute, so that they can fully absorb water and swell. Blow air on the treated wakame stems at a wind speed of 5m / s to remove surface water. Select wakame stems with a stem width of 3.0-2.0cm and cut them into approximately square wakame slices for later use.

[0032] (2) placing the kelp slices obtained in step (1) into a vacuum drying oven at a drying temperature of 60° C., a vacuum degree of −0.8 bar, and a drying time of 100 min, so that the moisture content of the kelp slices is reduced to 45%.

[0033] (3) Freezing: The dried wakame slices in step (2) are quickly placed in a cold storage and quick-frozen at -38°C for 2 hours.

[0034] (4) The frozen wakame slices were vacuum fried. The vacuum frying temperature was set at 100°C, the vacuum degree was -95 kPa, and the frying time was 10 minutes. The fried wakame slices were centrifuged for deoiling at a speed of 1000 rpm for 10 minutes.

[0035] (5) Freeze-dry the vacuum fried and de-oiled wakame slices, and quickly transfer the de-oiled wakame slices to a freeze dryer for freeze drying. The initial freezing temperature is set at -38°C, the initial freezing time is 1 hour, and the vacuum degree is controlled at 10Pa. Then enter the sublimation stage, the sublimation temperature is -30°C, this stage removes the residual moisture in the wakame slices. After the sublimation stage, secondary drying is performed at 30°C until the wakame slices reach constant weight. The resulting product is named VD-45%

[0036] The kelp chips prepared in Example 1 are yellow-brown in color, uniform in color, crispy in taste, have the unique fragrance of kelp, unique flavor, low in oil content, and are nutritious and healthy.

[0037] Example 2

[0038] The difference between Example 2 and Example 1 is that the drying time of vacuum drying is different, and the moisture content in the kelp slices after drying is different.

[0039] A dry combined low-oil puffed wakame snack food and a preparation method thereof, comprising the following steps:

[0040] (1) Rinse the salted wakame stems that are free of brown spots and odor and meet the "SC / T 3211-2019" standard to remove salt and impurities on the surface of the wakame stems. Then soak them in running water for 2 hours, with the flow rate maintained at 3 liters of water per kilogram of wakame per minute, so that they can fully absorb water and swell. Blow air on the treated wakame stems at a wind speed of 5m / s to remove surface water. Select wakame stems with a stem width of 3.0-2.0cm and cut them into approximately square wakame slices for later use.

[0041] (2) placing the kelp slices obtained in step (1) into a vacuum drying oven at a drying temperature of 60° C., a vacuum degree set to −0.8 bar, and a drying time of 180 min, so that the moisture content of the kelp slices is reduced to 15%.

[0042] (3) Freezing: The dried wakame slices in step (2) are quickly placed in a cold storage and quick-frozen at -38°C for 2 hours.

[0043] (4) The frozen wakame slices were vacuum fried. The vacuum frying temperature was set at 100°C, the vacuum degree was -95 kPa, and the frying time was 10 minutes. The fried wakame slices were centrifuged for deoiling at a speed of 1000 rpm for 10 minutes.

[0044] (5) Freeze-dry the vacuum fried and de-oiled kelp slices, and quickly transfer the de-oiled kelp slices to a freeze dryer for freeze drying. The initial freezing temperature is set at -38°C, the initial freezing time is 1 hour, and the vacuum degree is controlled at 10Pa. Then enter the sublimation stage, the sublimation temperature is -30°C, this stage removes the residual moisture in the kelp slices. After the sublimation stage, secondary drying is performed at 30°C until the kelp slices reach constant weight. The obtained product is named VD-15%.

[0045] The kelp chips prepared in Example 2 are yellow-brown in color, uniform in color, crispy in taste, have the unique fragrance of kelp, unique flavor, low in oil content, and are nutritious and healthy.

[0046] Example 3

[0047] The difference between Example 3 and Example 1 is that the vacuum degree and drying time during vacuum drying are different.

[0048] A dry combined low-oil puffed wakame snack food and a preparation method thereof, comprising the following steps:

[0049] (1) Rinse the salted wakame stems that are free of brown spots and odor and meet the "SC / T 3211-2019" standard to remove salt and impurities on the surface of the wakame stems. Then soak them in running water for 2 hours, with the flow rate maintained at 3 liters of water per kilogram of wakame per minute, so that they can fully absorb water and swell. Blow air on the treated wakame stems at a wind speed of 5m / s to remove surface water. Select wakame stems with a stem width of 3.0-2.0cm and cut them into approximately square wakame slices for later use.

[0050] (2) placing the kelp slices obtained in step (1) into a vacuum drying oven at a drying temperature of 60° C., a vacuum degree of −0.7 bar, and a drying time of 120 min, so that the moisture content of the kelp slices is reduced to 45%.

[0051] (3) Freezing: The dried wakame slices in step (2) are quickly placed in a cold storage and quick-frozen at -38°C for 2 hours.

[0052] (4) The frozen wakame slices were vacuum fried. The vacuum frying temperature was set at 100°C, the vacuum degree was -95 kPa, and the frying time was 10 minutes. The fried wakame slices were centrifuged for deoiling at a speed of 1000 rpm for 10 minutes.

[0053] (5) Freeze-dry the vacuum fried and de-oiled wakame slices, and quickly transfer the de-oiled wakame slices to a freeze dryer for freeze drying. The initial freezing temperature is set to -38°C, the initial freezing time is 1 hour, and the vacuum degree is controlled at 10Pa. Then enter the sublimation stage, the sublimation temperature is -30°C, and this stage removes the residual moisture in the wakame slices. After the sublimation stage, secondary drying is performed at a temperature of 30°C until the wakame slices reach a constant weight.

[0054] The kelp chips prepared in Example 3 are yellow-green in color, uniform in color, crispy in taste, have the unique fragrance of kelp, unique flavor, low in oil content, and are nutritious and healthy.

[0055] Example 4

[0056] The difference between Example 4 and Example 1 is that the vacuum degree and drying time during vacuum drying are different.

[0057] A dry combined low-oil puffed wakame snack food and a preparation method thereof, comprising the following steps:

[0058] (1) Rinse the salted wakame stems that are free of brown spots and odor and meet the "SC / T 3211-2019" standard to remove salt and impurities on the surface of the wakame stems. Then soak them in running water for 2 hours, with the flow rate maintained at 3 liters of water per kilogram of wakame per minute, so that they can fully absorb water and swell. Blow air on the treated wakame stems at a wind speed of 5m / s to remove surface water. Select wakame stems with a stem width of 3.0-2.0cm and cut them into approximately square wakame slices for later use.

[0059] (2) placing the kelp slices obtained in step (1) into a vacuum drying oven at a drying temperature of 60° C., a vacuum degree set to −0.9 bar, and a drying time of 90 min, so that the moisture content of the kelp slices is reduced to 45%.

[0060] (3) Freezing: The dried wakame slices in step (2) are quickly placed in a cold storage and quick-frozen at -38°C for 2 hours.

[0061] (4) The frozen wakame slices were vacuum fried. The vacuum frying temperature was set at 100°C, the vacuum degree was -95 kPa, and the frying time was 10 minutes. The fried wakame slices were centrifuged for deoiling at a speed of 1000 rpm for 10 minutes.

[0062] (5) Freeze-dry the kelp slices. The de-oiled kelp slices are quickly transferred to a freeze dryer for freeze drying. The initial freezing temperature is set at -38°C, the initial freezing time is 1 hour, and the vacuum degree is controlled at 10Pa. Then enter the sublimation stage, the sublimation temperature is -30°C, and this stage removes the residual moisture in the kelp slices. After the sublimation stage, secondary drying is performed at 30°C until the kelp slices reach a constant weight.

[0063] The kelp chips prepared in Example 4 are yellow-green in color, uniform in color, crispy in taste, have the unique fragrance of kelp, unique flavor, low in oil content, and are nutritious and healthy.

[0064] Comparative Example 1

[0065] The difference between Comparative Example 1 and Example 1 is that the vacuum drying step is omitted.

[0066] A dry combined low-oil puffed wakame snack food and a preparation method thereof, comprising the following steps:

[0067] (1) Rinse the salted wakame stems that are free of brown spots and odor and meet the "SC / T 3211-2019" standard to remove salt and impurities on the surface of the wakame stems. Then soak them in running water for 2 hours, with the flow rate maintained at 3 liters of water per kilogram of wakame per minute, so that they can fully absorb water and swell. Blow air on the treated wakame stems at a wind speed of 5m / s to remove surface water. Select wakame stems with a stem width of 3.0-2.0cm and cut them into approximately square wakame slices for later use.

[0068] (2) Freezing: The wakame slices obtained in step (1) are quickly placed in a cold storage and quick-frozen at -38°C for 2 hours.

[0069] (3) The frozen wakame slices were vacuum fried. The vacuum frying temperature was set at 100°C, the vacuum degree was -95 kPa, and the frying time was 10 minutes. The fried wakame slices were centrifuged for deoiling at a speed of 1000 rpm for 10 minutes.

[0070] (4) Freeze-dry the kelp slices. The de-oiled kelp slices are quickly transferred to a freeze dryer for freeze drying. The initial freezing temperature is set at -38°C, the initial freezing time is 1 hour, and the vacuum degree is controlled at 10Pa. Then enter the sublimation stage, the sublimation temperature is -30°C, and this stage removes the residual moisture in the kelp slices. After the sublimation stage, secondary drying is performed at 30°C until the kelp slices reach constant weight. The resulting product is named CON.

[0071] The kelp chips prepared in Comparative Example 1 are yellow-brown in color, high in oil content, uniform in color, crisp in taste, and have the unique fragrance and flavor of kelp.

[0072] Comparative Example 2

[0073] The difference between Comparative Example 2 and Example 1 is that the vacuum drying in step (2) is replaced by hot air drying.

[0074] A dry combined low-oil puffed wakame snack food and a preparation method thereof, comprising the following steps:

[0075] (1) Rinse the salted wakame stems that are free of brown spots and odor and meet the "SC / T 3211-2019" standard to remove salt and impurities on the surface of the wakame stems. Then soak them in running water for 2 hours, with the flow rate maintained at 3 liters of water per kilogram of wakame per minute, so that they can fully absorb water and swell. Blow air on the treated wakame stems at a wind speed of 5m / s to remove surface water. Select wakame stems with a stem width of 3.0-2.0cm and cut them into approximately square wakame slices for later use.

[0076] (2) placing the kelp slices obtained in step (1) into an electric blast drying oven at a drying temperature of 60° C., a wind speed of 1.0 m / s, and a drying time of 30 min, so that the moisture content of the kelp slices is reduced to 45%.

[0077] (3) Freezing: The dried kelp slices were quickly placed in a cold storage and quick-frozen at -38°C for 2 hours.

[0078] (4) The frozen wakame slices were vacuum fried. The vacuum frying temperature was set at 100°C, the vacuum degree was -95 kPa, and the frying time was 10 minutes. The fried wakame slices were centrifuged for deoiling at a speed of 1000 rpm for 10 minutes.

[0079] (5) Freeze-dry the kelp slices. The de-oiled kelp slices are quickly transferred to a freeze dryer for freeze drying. The initial freezing temperature is set at -38°C, the initial freezing time is 1 hour, and the vacuum degree is controlled at 10Pa. Then enter the sublimation stage, the sublimation temperature is -30°C, and this stage removes the residual moisture in the kelp slices. After the sublimation stage, secondary drying is performed at 30°C until the kelp slices reach constant weight. The resulting product is named HD-45%.

[0080] The kelp chips prepared in Comparative Example 2 are yellow-green in color, uniform in color, crispy in taste, have the unique fragrance of kelp, unique flavor, low in oil content, and are nutritious and healthy.

[0081] Comparative Example 3

[0082] The difference between Comparative Example 3 and Example 1 is that the vacuum drying in step (2) is replaced by hot air drying, and the moisture content of the kelp slices after drying is different.

[0083] A dry combined low-oil puffed wakame snack food and a preparation method thereof, comprising the following steps:

[0084] (1) Rinse the salted wakame stems that are free of brown spots and odor and meet the "SC / T 3211-2019" standard to remove salt and impurities on the surface of the wakame stems. Then soak them in running water for 2 hours, with the flow rate maintained at 3 liters of water per kilogram of wakame per minute, so that they can fully absorb water and swell. Blow air on the treated wakame stems at a wind speed of 5m / s to remove surface water. Select wakame stems with a stem width of 3.0-2.0cm and cut them into approximately square wakame slices for later use.

[0085] (2) placing the kelp slices obtained in step (1) into an electric blast drying oven at a drying temperature of 60° C., a wind speed of 1.0 m / s, and a drying time of 60 min, so that the moisture content of the kelp slices is reduced to 15%.

[0086] (3) Freezing: The dried kelp slices were quickly placed in a cold storage and quick-frozen at -38°C for 2 hours.

[0087] (4) The frozen wakame slices were vacuum fried. The vacuum frying temperature was set at 100°C, the vacuum degree was -95 kPa, and the frying time was 10 minutes. The fried wakame slices were centrifuged for deoiling at a speed of 1000 rpm for 10 minutes.

[0088] (5) Freeze-dry the kelp slices. The de-oiled kelp slices are quickly transferred to a freeze dryer for freeze drying. The initial freezing temperature is set at -38°C, the initial freezing time is 1 hour, and the vacuum degree is controlled at 10Pa. Then enter the sublimation stage, the sublimation temperature is -30°C, and this stage removes the residual moisture in the kelp slices. After the sublimation stage, secondary drying is performed at 30°C until the kelp slices reach constant weight. The resulting product is named HD-15%.

[0089] The kelp chips prepared in Comparative Example 3 are yellow-green in color, uniform in color, crispy in taste, have the unique fragrance of kelp, unique flavor, low in oil content, and are nutritious and healthy.

[0090] Comparative Example 4

[0091] The difference between Comparative Example 4 and Example 1 is that the vacuum drying in step (2) is replaced by infrared drying.

[0092] A dry combined low-oil puffed wakame snack food and a preparation method thereof, comprising the following steps:

[0093] (1) Rinse the salted wakame stems that are free of brown spots and odor and meet the "SC / T 3211-2019" standard to remove salt and impurities on the surface of the wakame stems. Then soak them in running water for 2 hours, with the flow rate maintained at 3 liters of water per kilogram of wakame per minute, so that they can fully absorb water and swell. Blow air on the treated wakame stems at a wind speed of 5m / s to remove surface water. Select wakame stems with a stem width of 3.0-2.0cm and cut them into approximately square wakame slices for later use.

[0094] (2) placing the kelp slices obtained in step (1) into an infrared drying oven at a drying temperature of 60° C., an infrared light wavelength of 1.5 μm to 5 μm, a drying power of 450 W, and a drying time of 80 min, so that the moisture content of the kelp slices is reduced to 45%.

[0095] (3) Freezing: The dried kelp slices were quickly placed in a cold storage and quick-frozen at -38°C for 2 hours.

[0096] (4) The frozen wakame slices were vacuum fried. The vacuum frying temperature was set at 100°C, the vacuum degree was -95 kPa, and the frying time was 10 minutes. The fried wakame slices were centrifuged for deoiling at a speed of 1000 rpm for 10 minutes.

[0097] (5) Freeze-dry the kelp slices, and quickly transfer the de-oiled kelp slices to a freeze dryer for freeze drying. The initial freezing temperature is set at -38°C, the initial freezing time is 1 hour, and the vacuum degree is controlled at 10Pa. Then enter the sublimation stage, the sublimation temperature is -30°C, and this stage removes the residual moisture in the kelp slices. After the sublimation stage, secondary drying is performed at 30°C until the kelp slices reach constant weight. The resulting product is named ID-45%.

[0098] The kelp chips prepared in Comparative Example 4 are yellow-green in color, uniform in color, crisp in taste, have the unique fragrance of kelp, unique flavor, low in oil content, and are nutritious and healthy.

[0099] Comparative Example 5

[0100] The difference between Comparative Example 5 and Example 1 is that the vacuum drying in step (2) is replaced by infrared drying, and the moisture content of the kelp slices after drying is different.

[0101] A dry combined low-oil puffed wakame snack food and a preparation method thereof, comprising the following steps:

[0102] (1) Rinse the salted wakame stems that are free of brown spots and odor and meet the "SC / T 3211-2019" standard to remove salt and impurities on the surface of the wakame stems. Then soak them in running water for 2 hours, with the flow rate maintained at 3 liters of water per kilogram of wakame per minute, so that they can fully absorb water and swell. Blow air on the treated wakame stems at a wind speed of 5m / s to remove surface water. Select wakame stems with a stem width of 3.0-2.0cm and cut them into approximately square wakame slices for later use.

[0103] (2) placing the kelp slices obtained in step (1) into an infrared drying oven at a drying temperature of 60° C., an infrared light wavelength of 1.5 μm to 5 μm, a drying power of 450 W, and a drying time of 180 min, so that the moisture content of the kelp slices is reduced to 15%.

[0104] (3) Freezing: The dried kelp slices were quickly placed in a cold storage and quick-frozen at -38°C for 2 hours.

[0105] (4) The frozen wakame slices were vacuum fried. The vacuum frying temperature was set at 100°C, the vacuum degree was -95 kPa, and the frying time was 10 minutes. The fried wakame slices were centrifuged for deoiling at a speed of 1000 rpm for 10 minutes.

[0106] (5) Freeze-dry the kelp slices, and quickly transfer the de-oiled kelp slices to a freeze dryer for freeze drying. The initial freezing temperature is set at -38°C, the initial freezing time is 1 hour, and the vacuum degree is controlled at 10Pa. Then enter the sublimation stage, the sublimation temperature is -30°C, and this stage removes the residual moisture in the kelp slices. After the sublimation stage, secondary drying is performed at 30°C until the kelp slices reach constant weight. The resulting product is named ID-15%.

[0107] The kelp chips prepared in Comparative Example 5 are dark green, uniform in color, crispy in taste, have the unique fragrance of kelp, unique flavor, low in oil content, and are nutritious and healthy.

[0108] Detection test

[0109] Product performance testing

[0110] The prepared wakame chips were subjected to puncture test, using a probe of P / 2, a trigger force of 5g, and a puncture distance of 2cm. The three data of fracture distance, puncture fracture strength, and puncture fracture work were obtained, among which the fracture distance can reflect the brittleness, and the puncture fracture work can reflect the hardness. The smaller the fracture distance, the higher the brittleness of the chips, and the larger the puncture fracture work, the greater the hardness of the chips.

[0111] The puncture performance results of the wakame chips in Examples 1 to 4 and Comparative Examples 1 to 5 are as follows: Figure 1-4 shown.

[0112] Depend on Figure 1 and Figure 2 It can be seen that the hardness and crispness of the kelp chips prepared by different drying methods before freezing are quite different. Compared with Comparative Example 1, the rupture distance and puncture rupture strength of the kelp chips prepared by drying before freezing have obvious changes in the puncture test. Among them, the kelp chips prepared by vacuum drying the kelp slices before freezing have relatively good indicators in terms of fracture distance and puncture rupture strength. And when the kelp is dried to a moisture content of 45% and then frozen, fried and freeze-dried, the crispness of the prepared chips is significantly improved, the hardness is reduced, and a better crisp taste is obtained.

[0113] Depend on Figure 3 and Figure 4 It can be seen that the vacuum degree during vacuum drying also has a great influence on the hardness and crispness of the final prepared kelp chips. Specifically, the higher the vacuum degree, the greater the crispness of the kelp chips and the lower the hardness. However, a higher vacuum degree may cause stratification in the center of the kelp sample. During the frying process, the stratified kelp samples tend to expand into a spherical shape and absorb a large amount of oil, resulting in a poor yield. Therefore, a vacuum degree of -0.8 bar was selected to dry the kelp.

[0114] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a dry combined low-oil puffed wakame snack food, characterized in that: The following steps are involved: S1. Cleaning and processing of raw materials: rinsing and draining the wakame stems and cutting them into wakame slices for later use; S2, drying: placing the wakame slices obtained in step S1 in a vacuum drying device for dehydration; S3, freezing: quickly placing the dried wakame slices in step S2 into a cold storage for freezing; S4, vacuum frying: vacuum frying the frozen wakame slices in step S3, and centrifugally de-oiling after frying; S5, freeze drying: the kelp slices after deoiling in step S4 are quickly placed in a freeze dryer, and subjected to primary freezing, sublimation drying, and secondary drying in sequence to obtain kelp crispy slices.

2. The preparation method according to claim 1, characterized in that: The preparation process of the kelp slices in step S1 is as follows: the salted kelp stems without brown spots and odor are first rinsed, then soaked in running water for 2 to 3 hours, the water flow rate is 3 to 5 liters of water per kilogram of kelp per minute, the soaked kelp stems are blown with air at a wind speed of 5 m / s to remove surface water, and kelp stems with a stem width of 2.0 to 3.0 cm are selected and cut into square kelp slices.

3. The preparation method according to claim 1, characterized in that: In step S2, the kelp slices are vacuum dried at a temperature of 55-65°C and a vacuum degree of -0.8 bar, and the kelp slices are dried until the moisture content is 40-50%.

4. The preparation method according to claim 1, characterized in that: In step S3, the freezing temperature is -38 to -40°C, and the freezing time is 1 to 3 hours.

5. The preparation method according to claim 1, characterized in that: In step S4, the vacuum frying temperature is 95 to 105°C, the vacuum degree is -85 to -95 kPa, and the frying time is 8 to 15 minutes.

6. The preparation method according to claim 1, characterized in that: During centrifugal deoiling, the centrifugal speed was 1000 rpm and the centrifugal time was 10 min.

7. The preparation method according to claim 1, characterized in that: In step S5, during freeze drying, the initial freezing temperature is set to -38 to -40°C, the initial freezing time is 1 to 2 hours, and the vacuum degree is 10 to 100 Pa.

8. The preparation method according to claim 1, characterized in that: In step S5, during freeze drying, the sublimation temperature is -10 to -30°C, and the temperature during secondary drying is 30 to 40°C.

9. Wakame chips prepared according to the method according to any one of claims 1 to 8.

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