CN113412923A

CN113412923A - Method for processing castanopsis sclerophylla seeds

Info

Publication number: CN113412923A
Application number: CN202110798842.6A
Authority: CN
Inventors: 陆胜民; 王杨柳; 李雨潼; 王瑞平
Original assignee: Ruian Fengchao Ecological Agriculture Co ltd
Current assignee: Ruian Fengchao Ecological Agriculture Co ltd
Priority date: 2021-07-15
Filing date: 2021-07-15
Publication date: 2021-09-21
Anticipated expiration: 2041-07-15
Also published as: CN113412923B

Abstract

The invention relates to the technical field of food processing, and particularly discloses a castanopsis sclerophylla seed processing method, which comprises the following steps of (a) placing a proper amount of processed castanopsis sclerophylla seeds in a soaking container; (b) adding a proper amount of distilled water into the soaking container, wherein the adding amount of the distilled water is 0.03-0.07 of the material-liquid ratio of the castanopsis sclerophylla seeds to the distilled water; (c) heating distilled water to 30-50 ℃ to soak the castanopsis sclerophylla seeds, and soaking for 1.5-2.5 h to obtain the castanopsis sclerophylla seeds after the tannin is removed. The method has the characteristics of good tannin removing effect and capability of determining the optimal tannin removing condition.

Description

Method for processing castanopsis sclerophylla seeds

Technical Field

The invention relates to the technical field of food processing, in particular to a castanopsis sclerophylla seed processing method.

Background

Castanopsis Sclerophylla (Castanopsis Sclerophylolla), plant of Conus of Fagaceae (Beechiaceae), Castanopsis Sclerophylla extract, and radix ErigerontisThe tree, castanopsis mollissima and ceruleus solander belong to the secondary protection plants of China. In China, the castanopsis sclerophylla is mainly distributed in subtropical deciduous broad-leaved forests and subtropical evergreen broad-leaved forest zones in the north of five mountains of the Yangtze river, and generally grows in hills and low mountain areas with the elevation below 1000 m. The leaves grown from Castanopsis Sclerophylla are thick, so that forest planting has effects of preventing wind and fire, and branches and leaves thereof are used for CO₂The resistance of the plant is strong, can be tolerated below 425 ℃, and is an excellent fire-proof tree species which can be selected in forest planting. The castanopsis sclerophylla fruit is called castanopsis sclerophylla seed, and castanopsis sclerophylla is called as bitter pearl fruit. The castanopsis sclerophylla seed contains more starch (less fruit source starch), and is edible in China since ancient times by sun drying, removing the outer shell and the skin on the kernel, repeatedly soaking with fresh water for several days to remove the unique bitter taste, grinding into slurry like bean curd, cooling, solidifying into dark brown dried fruit, and castanopsis sclerophylla bean curd (without bean component), and drying for long-term storage. The castanopsis sclerophylla bean curd has strong local smell, is fresh and smooth when being eaten, has soft and smooth mouthfeel, has bitter and astringent taste, and has a special flavor. The castanopsis sclerophylla fruit can also be used as a raw material of a medicament, and the powder prepared from the castanopsis sclerophylla fruit is a folk prescription which is frequently used by people in certain regions in south of China for treating diarrhea; li Shizhen recorded in Ben Cao gang mu, the semen Castanopsis Sclerophyllae fruit has effects of invigorating qi, improving eyesight, strengthening tendons and bones, tonifying yang qi, tonifying consumptive disease, strengthening waist and knee. Nowadays, the castanopsis sclerophylla can be used as a new resource development of edible starch and also can be used as a base material of health-care food. In addition, although the leisure fried snacks prepared from the castanopsis sclerophylla seeds are blank in the market, the castanopsis sclerophylla seeds have wide development prospect.

Castanopsis sclerophylla is plant of genus Castanopsis of family Fagaceae (Fagaceae), and research shows that the plant of family Fagaceae is rich in tannin components including hydrolyzed tannin, condensed tannin, and compound tannin. Complex tannins usually contain D-hamamelis glycosyl, cyclohexadentanol (proto-, scyllo-), and triterpenoid saponins, quinic acid, shikimic acid, etc. In conifers, triterpenes and their glycosides are also commonly present as central groups of some complex tannins. In addition, the plant of this family also contains flavonoids and alkaloids. Comparison with other tannin extracts shows that Castanopsis Sclerophylla uniquely accumulates chlorogenic acid and dimeric ellagitannin, i.e., triterpene hexahydroxy diphenol ester. The Castanopsis Sclerophylla seed shell contains bitter and astringent components such as tannic acid and polyphenol, impurities and microorganism such as mold. The bitter and astringent components are removed to improve the mouthfeel and make the product more popular, and the cleaning is to ensure the safety of the product. At present, the castanopsis sclerophylla seed processing research report exists in China, but the research on the bitter and astringent removing method is few. Tannic acid is an important representative of astringency in fruits, and the higher the degree of astringency removal, the lower the content of tannic acid in the fruit. Researches show that the astringency in most fruits is caused by the combination of tannic acid and protein in the oral cavity, and when the content of tannic acid is 0.03-0.1%, the fruits have cool mouthfeel and also have the function of strengthening sour taste; when the content of tannic acid is more than 1%, the fruit has strong astringency. With the improvement of living standard, the requirement of the public on the flavor of food is gradually improved, and the influence of tannic acid on the flavor of food and the effect of tannic acid on human bodies become hot spots of research in recent years.

Therefore, the existing processing of the castanopsis sclerophylla seeds has the problems of poor tannin removing effect, uncertain optimal tannin removing conditions and no research on the aspect of being used as stir-fried food.

Disclosure of Invention

The invention provides a castanopsis sclerophylla seed processing method which has a good tannin removal effect and can determine the best tannin removal condition in order to solve the technical problems existing in the processing of the castanopsis sclerophylla seeds.

The technical scheme of the invention is as follows: the castanopsis sclerophylla seed processing method comprises the following steps,

(a) placing a proper amount of the processed castanopsis sclerophylla seeds in a soaking container;

(b) adding a proper amount of distilled water into the soaking container, wherein the adding amount of the distilled water is 0.03-0.07 of the material-liquid ratio of the castanopsis sclerophylla seeds to the distilled water;

(c) heating distilled water to 30-50 ℃ to soak the castanopsis sclerophylla seeds, and soaking for 1.5-2.5 h to obtain the castanopsis sclerophylla seeds after the tannin is removed.

The invention adopts the mode of soaking the castanopsis sclerophylla seeds in warm water to remove tannic acid in the castanopsis sclerophylla seeds, thereby achieving the purpose of removing astringent taste of the castanopsis sclerophylla seeds and providing raw materials with better quality and mouthfeel for the subsequent castanopsis sclerophylla seeds as fried food; the invention extracts the optimal material-liquid ratio, soaking temperature and soaking time of the tannic acid in the castanopsis sclerophylla seeds by warm water soaking through experimental research, and particularly determines that the material-liquid ratio of the castanopsis sclerophylla seeds to distilled water is 0.03-0.07, the soaking temperature is 30-50 ℃, and the soaking time is 1.5-2.5 h, and the result determines that the removal rate of the tannic acid can reach more than 60 percent, so that the tannic acid is fully dissolved into the distilled water, and the invention has better effect of removing the tannic acid, and can provide a raw material with lower degree of bitterness for the subsequent processing of the castanopsis sclerophylla seeds into fried food by adopting a simple method.

Preferably, the preparation of the primary taste castanopsis sclerophylla seed finished product comprises the following steps,

(d11) taking a proper amount of castanopsis sclerophylla seeds from which tannic acid is removed, cleaning and draining the proper amount of castanopsis sclerophylla seeds, putting the cleaned and drained castanopsis sclerophylla seeds into a drying oven, and drying the castanopsis sclerophylla seeds for 40-60 min at the temperature of 110-130 ℃;

(d12) and (d11) putting the dried castanopsis sclerophylla seeds in a sand frying pan, and stir-frying the castanopsis sclerophylla seeds in sand for 5min to 10min at the temperature of 95 ℃ to 105 ℃ to obtain the primary taste castanopsis sclerophylla seed finished product.

The castanopsis sclerophylla seeds after tannin removal are used as raw materials, and after the castanopsis sclerophylla seeds are washed, drained, baked and fried in sequence, fried castanopsis sclerophylla seed food with no bitter or slightly bitter astringent at the entrance and exit and acceptable bitter degree is prepared, fried castanopsis sclerophylla seed food with unique faint scent of castanopsis sclerophylla and no other peculiar smell is prepared, and fried castanopsis sclerophylla seed food with moderate mouth feel and hardness and easy acceptance is prepared; wherein the specific limitations of the drying temperature, the drying time, the sand frying temperature and the sand frying time are all to finally prepare the original taste castanopsis sclerophylla seed product with superior taste and better fragrance.

Preferably, the preparation of the salty castanopsis sclerophylla seed finished product comprises the following steps,

(d21) taking a proper amount of castanopsis sclerophylla seeds subjected to tannin removal, cleaning a proper amount of castanopsis sclerophylla seeds, and placing the cleaned castanopsis sclerophylla seeds into a boiling pot;

(d22) adding a proper amount of salt into the boiler in the step (d21), and then boiling for 50-70 min at the temperature of 90-100 ℃;

(d23) draining the castanopsis sclerophylla seeds after the boiling is finished, and placing the drained castanopsis sclerophylla seeds in a drying oven to dry for 40-60 min at the temperature of 110-130 ℃;

(d24) and (d23) putting the dried castanopsis sclerophylla seeds in a sand frying pan, and stir-frying the castanopsis sclerophylla seeds in sand for 5min to 10min at the temperature of 95 ℃ to 105 ℃ to obtain the finished products of the salty castanopsis sclerophylla seeds.

The castanopsis sclerophylla seeds after tannin removal are used as raw materials, and after the castanopsis sclerophylla seeds are washed, added with salt for stewing, baked and fried in sequence, fried castanopsis sclerophylla seed food with no bitter and astringent taste or slightly bitter and astringent taste at the entrance and exit and acceptable bitter and astringent degree is prepared, fried castanopsis sclerophylla seed food with moderate salty taste is prepared, and fried castanopsis sclerophylla seed food with moderate mouth feel and hardness and easy acceptance is prepared; wherein the specific limitations of the cooking temperature, the cooking time, the drying temperature, the drying time, the sand frying temperature and the sand frying time are all for finally preparing the salty castanopsis sclerophylla seed product with superior taste and proper salty taste.

Preferably, the preparation of the finished product of the castanopsis sclerophylla comprises the following steps,

(d31) taking a proper amount of castanopsis sclerophylla seeds subjected to tannin removal, cleaning a proper amount of castanopsis sclerophylla seeds, and placing the cleaned castanopsis sclerophylla seeds into a boiling pot;

(d32) adding a proper amount of crystalline sugar powder into the boiling pot in the step (d31), and boiling at 90-100 ℃ for 50-70 min;

(d33) draining the castanopsis sclerophylla seeds after the boiling is finished, and placing the drained castanopsis sclerophylla seeds in a drying oven to dry for 40-60 min at the temperature of 110-130 ℃;

(d34) and (d33) putting the dried castanopsis sclerophylla seeds in a sand frying pan, and stir-frying the castanopsis sclerophylla seeds in sand for 5min to 10min at the temperature of 95 ℃ to 105 ℃ to obtain the finished product of the sweet castanopsis sclerophylla seeds.

The castanopsis sclerophylla seeds after tannin removal are used as raw materials, and are sequentially washed, added with sugar powder, steamed, roasted and fried, so that fried castanopsis sclerophylla seed food with no bitter and astringent taste or slightly bitter and astringent taste at the entrance and exit and acceptable bitter and astringent degree is prepared, fried castanopsis sclerophylla seed food with moderate sweet taste is prepared, and fried castanopsis sclerophylla seed food with moderate mouth feel and hardness and easy acceptance is prepared; wherein the specific limitations of the cooking temperature, the cooking time, the drying temperature, the drying time, the sand frying temperature and the sand frying time are all for finally preparing the sweet castanopsis sclerophylla seed product with superior taste and proper sweet taste.

Preferably, the castanopsis sclerophylla seed in the step (a) is processed by,

placing the castanopsis sclerophylla seed raw material into a drying oven, and drying at the temperature of 70-90 ℃ until the dry weight ratio of the castanopsis sclerophylla seed raw material is 80%. Drying the excessive water in the castanopsis sclerophylla seed raw material under the limited temperature condition, and finally drying until the dry weight ratio of the castanopsis sclerophylla seed raw material is 80%, achieving the subsequent de-astringency and frying the castanopsis sclerophylla seed raw material with the best water content, and strictly controlling the dry weight ratio of the castanopsis sclerophylla seed raw material, so that the subsequent de-astringency ratio of castanopsis sclerophylla seed is higher, and the taste of the fried castanopsis sclerophylla seed finished product is better; meanwhile, the sterilization effect can be achieved during drying, and the quality health of the subsequently prepared castanopsis sclerophylla seed finished product is better ensured.

Preferably, the drawing of the standard curve of the monopenin in the castanopsis sclerophylla seeds comprises the following steps,

(A) weighing 5mg of tannic acid, taking a 50mL volumetric flask, adding the tannic acid into the volumetric flask, and fixing the volume to the scale mark of the volumetric flask by using distilled water to prepare a tannic acid standard solution of 0.1 mg/mL;

(B) taking 0 mu L, 400 mu L, 800 mu L, 1200 mu L, 1600 mu L and 2000 mu L of tannic acid standard solution in 6 volumetric flasks of 25mL, and adding 2.5mL of ferric iron solution in each volumetric flask;

(C) heating each volumetric flask added with the ferric iron solution in a water bath at the temperature of 70-90 ℃ for 15-25 min, and then cooling to room temperature;

(D) respectively adding 8mL of o-diazophenanthrene buffer solution into each volumetric flask cooled to room temperature, fixing the volume of the scale mark of the volumetric flask by using distilled water, standing for 5-15 min, and measuring the absorbance of the solution in each volumetric flask at 505 nm;

(E) according to the concentration of the tannic acid in each volumetric flask and the corresponding absorbance, the standard curve equation of the tannic acid is obtained as follows,

y＝0.1535x+0.2472(R²＝0.9987)，

wherein x represents the concentration of tannic acid, y represents the absorbance, R²Representing the correlation coefficient.

According to the invention, ferric iron solution is added into a plurality of volumetric flasks with different tannin measuring standards, water bath is carried out for a limited time under the condition of a limited temperature, ferric iron ions and tannic acid are fully combined, then a limited-measuring o-phenanthroline buffer solution is added, the o-phenanthroline and the ferric iron ions are fully combined into a 1, 10-o-phenanthroline-iron (III) complex after standing for a limited time, and the absorbance corresponding to the tannin content in each volumetric flask can be accurately measured by an absorption photometry, so that the standard curve equation of the tannic acid can be accurately obtained, an accurate and simple measuring method is provided for the subsequent determination of the tannin content in the castanopsis sclerophylla, the induction method of the standard curve equation of the tannic acid is simple, and the accuracy of the induction equation is higher.

Preferably, the method for measuring the content of the tannic acid in the castanopsis sclerophylla seeds comprises the following steps,

putting 25g of the processed castanopsis sclerophylla seeds into a wall-breaking food machine, adding 175g of distilled water into the wall-breaking food machine for grinding to obtain castanopsis sclerophylla seed stock solution with the grinding material ratio of 1:9, wherein the grinding time is 20-40 s;

(ii) transferring the castanopsis sclerophylla seed stock solution into a beaker, and soaking in a water bath at the temperature of 30-50 ℃ for 1.5-2.5 h;

(iii) after soaking, carrying out reduced pressure suction filtration on the feed liquid in the beaker to obtain filtrate, namely the stock solution to be measured;

(iv) placing 0.5mL of stock solution to be detected in a 25mL volumetric flask, and adding 2.5mL of ferric iron solution in the volumetric flask;

(v) placing the volumetric flask added with the ferric iron solution in a water bath at 70-90 ℃ for heating for 15-25 min, and then cooling to room temperature;

(vi) adding 8mL of o-diazophenanthrene buffer solution into the volumetric flask cooled to room temperature, fixing the volume of the volumetric flask to a scale mark by using distilled water, and standing for 5-15 min;

(vii) after the standing is finished, taking a proper amount of the solution after the standing, diluting the taken solution after the standing by using distilled water by 10 times, and measuring the absorbance at 505 nm;

(viii) substituting the measured absorbance value into a standard curve equation of the tannic acid to obtain the concentration of the tannic acid in the dilution of the semen Castanopsis Sclerophyllae stock solution.

The invention selects a proper amount of castanopsis sclerophylla seeds, then selects a proper amount of distilled water to be put into a broken wall food processor for grinding, and the castanopsis sclerophylla seeds raw liquid with a proper material ratio is prepared after grinding for a limited time, so that the castanopsis sclerophylla seeds particles in the finally prepared castanopsis sclerophylla seeds raw liquid are uniformly distributed; soaking the semen Castanopsis Sclerophyllae raw liquid at a limited temperature for a limited time to sufficiently remove tannic acid in the semen Castanopsis Sclerophyllae raw liquid to achieve the purpose of removing astringency; carrying out vacuum filtration to obtain the semen Castanopsis Sclerophyllae stock solution to be detected after removing tannic acid; adding a ferric iron solution into a volumetric flask containing a proper amount of castanopsis sclerophylla seed stock solution to be measured, carrying out water bath for a limited time under the condition of a limited temperature, fully combining ferric iron ions and tannic acid, adding a limited-measurement o-phenanthrene buffer solution, standing for a limited time, fully combining o-phenanthrene and ferric iron ions into a 1, 10-o-phenanthrene-iron (III) complex, conveniently and accurately measuring the absorbance corresponding to the content of tannic acid in each volumetric flask by using an absorbance photometry subsequently, diluting the solution after standing for a proper amount of times, accurately measuring the absorbance in the dilution by using the absorbance photometry, reversely introducing the measured absorbance into the summarized tannic acid standard curve equation to obtain the concentration of tannic acid in the castanopsis sclerophylla seed stock solution, and having a simple measurement method for the concentration of tannic acid in the castanopsis sclerophylla seed stock solution, the accuracy of the measurement is higher.

Preferably, the calculation formula of the content of the tannic acid in the castanopsis sclerophylla seeds of the dry weight of the raw material is,

the calculation formula of the deacidification rate is as follows,

the calculation method of the content of the tannic acid and the rate of the tannin removal is simple, and the calculation accuracy is higher.

Preferably, the concentration of the phenanthroline buffer solution is 0.015 mol/L;

the preparation method of the phenanthroline buffer solution with the concentration of 0.015mol/L comprises the steps of taking 1.487g of 1, 10-phenanthroline, dissolving the 1, 10-phenanthroline in distilled water, placing the solution in a 500mL volumetric flask, and fixing the volume to the scale mark of the volumetric flask by using the distilled water to obtain the phenanthroline buffer solution; the mass concentration of the added salt is 14%; the preparation method of the salt-added concentration comprises boiling 100g of semen Castanopsis Sclerophyllae, adding 14g of salt, and adding 100mL of water. The o-phenanthroline buffer solution with the limited concentration is added, so that the o-phenanthroline buffer solution can be more fully, quickly and completely complexed with a ferric iron solution to form a 1, 10-o-phenanthroline-iron (III) complex, the content of tannic acid in the castanopsis sclerophylla seeds can be accurately measured by using an ultraviolet-visible spectrophotometry, the preparation method of the o-phenanthroline buffer solution with the limited concentration is simpler, and the concentration accuracy of the prepared solution is higher; the mass concentration of the salt added in the food is summarized according to a plurality of experimental verifications, so that the finally prepared salty castanopsis sclerophylla product has proper salty taste and good mouthfeel.

Preferably, the concentration of the ferric iron solution is 0.01 mol/L;

the preparation method of the ferric iron solution with the concentration of 0.01mol/L comprises the steps of taking 2.51g of ferric ammonium sulfate dodecahydrate, dissolving the ferric ammonium sulfate dodecahydrate by using distilled water, adding 0.5mL of concentrated sulfuric acid into the dissolved solution, transferring the solution into a 500mL volumetric flask, and fixing the volume to the scale mark of the volumetric flask by using distilled water to obtain the ferric iron solution; the standard of the added crystal sugar powder is that 100g of castanopsis sclerophylla seeds are boiled and 40g of crystal sugar powder is added. Adding a ferric iron solution with a limited concentration, so that the ferric iron solution can be more fully, quickly and completely combined with tannic acid and can also be more fully, quickly and completely complexed with a phenanthroline buffer solution added later to form a 1, 10-phenanthroline-iron (III) complex, and therefore the content of tannic acid in castanopsis sclerophylla seeds is accurately measured by using an ultraviolet-visible spectrophotometry, wherein the preparation method of the ferric iron solution with the limited concentration is simpler, and the concentration accuracy of the prepared solution is higher; the amount of the added crystal sugar powder is summarized according to a plurality of experimental verifications, so that the finally prepared sweet castanopsis sclerophylla seed product has proper sweetness and better mouthfeel.

The invention has the following beneficial effects:

(1) the method comprises the following steps of soaking castanopsis sclerophylla seeds in warm water to remove tannic acid in the castanopsis sclerophylla seeds, so as to achieve the purpose of removing astringent taste of the castanopsis sclerophylla seeds and provide raw materials with better quality and mouthfeel for the subsequent castanopsis sclerophylla seeds serving as fried food;

(2) through experimental research, the optimal material-liquid ratio, soaking temperature and soaking time of the tannic acid in the castanopsis sclerophylla seeds soaked and refined in warm water to remove the tannic acid are extracted, the material-liquid ratio of the castanopsis sclerophylla seeds to distilled water is determined to be 0.03-0.07, the soaking temperature is 30-50 ℃, the soaking time is 1.5-2.5 h, the result is determined that the removal rate of the tannic acid can reach more than 60%, so that the tannic acid is fully dissolved in the distilled water, the good effect of removing the tannic acid is achieved, and the simple method can provide a raw material with low degree of astringency for the subsequent processing of the castanopsis sclerophylla seeds into fried food.

Drawings

FIG. 1 is a graph of tannic acid standard in the present invention;

FIG. 2 is a graph of the ratio of dehydrotannic acid for different soaking times in accordance with the present invention;

FIG. 3 is a graph of the rate of dehydrotannic acid for different soaking temperatures in accordance with the present invention;

FIG. 4 is a graph of the ratio of the dehydrotannic acid in different soaking solutions according to the present invention;

FIG. 5 is a radar chart showing sensory evaluation results in the present invention.

Detailed Description

The present invention will be further described with reference to the following examples and drawings, but the present invention is not limited thereto.

The castanopsis sclerophylla seed processing method comprises the following steps,

The preparation method of the original taste castanopsis sclerophylla seed product comprises the following steps,

The preparation method of the salty castanopsis sclerophylla seed product comprises the following steps,

The preparation method of the sweet castanopsis sclerophylla seed product comprises the following steps,

The castanopsis sclerophylla seed in the step (a) is processed by the following steps,

placing the castanopsis sclerophylla seed raw material into a drying oven, and drying at the temperature of 70-90 ℃ until the dry weight ratio of the castanopsis sclerophylla seed raw material is 80%.

The drawing of the standard curve of the tannic acid in the castanopsis sclerophylla seeds comprises the following steps,

(A) weighing a proper amount of tannic acid, taking a volumetric flask with a proper volume, adding the tannic acid into the volumetric flask, and fixing the volume to the scale mark of the volumetric flask by using distilled water to prepare a tannic acid standard solution of 0.1 mg/mL;

y＝0.1535x+0.2472(R²＝0.9987)，

The method for measuring the content of the tannic acid in the castanopsis sclerophylla seeds comprises the following steps,

putting the processed castanopsis sclerophylla seeds into a broken-wall food machine, adding distilled water into the broken-wall food machine for grinding to obtain castanopsis sclerophylla seed stock solution with the grinding material ratio of 1:9, wherein the grinding time is 20-40 s;

The calculation formula of the content of the tannic acid in the castanopsis sclerophylla seeds of the dry weight of the raw materials is as follows,

the calculation formula of the deacidification rate is as follows,

the concentration of the phenanthroline buffer solution is 0.015 mol/L;

the preparation method of the phenanthroline buffer solution with the concentration of 0.015mol/L comprises the steps of taking 1.487g of 1, 10-phenanthroline, dissolving the 1, 10-phenanthroline in distilled water, placing the solution into a 500mL volumetric flask, and fixing the volume to the scale mark of the volumetric flask by using the distilled water to obtain the phenanthroline buffer solution; adding salt, decocting semen Castanopsis Sclerophyllae 100g, adding salt 14g, and adding water 100 mL.

The concentration of the ferric iron solution is 0.01 mol/L;

the preparation method of the ferric iron solution with the concentration of 0.01mol/L comprises the steps of taking 2.51g of ferric ammonium sulfate dodecahydrate, dissolving the ferric ammonium sulfate dodecahydrate by using distilled water, adding 0.5mL of concentrated sulfuric acid into the dissolved solution, transferring the solution into a 500mL volumetric flask, and fixing the volume to the scale mark of the volumetric flask by using distilled water to obtain the ferric iron solution; adding crystalline sugar powder, decocting to obtain 100g of semen Castanopsis Sclerophyllae, and adding 40g of crystalline sugar powder.

Example (b):

(b) adding appropriate amount of distilled water into the soaking container, wherein the addition amount of the distilled water is 0.05 of the material-liquid ratio of the castanopsis sclerophylla seeds to the distilled water;

(c) heating distilled water to 40 deg.C, soaking semen Castanopsis Sclerophyllae seed for 2 hr to obtain semen Castanopsis Sclerophyllae seed without tannic acid.

(d11) taking a proper amount of castanopsis sclerophylla seeds from which tannic acid is removed, cleaning and draining the castanopsis sclerophylla seeds, putting the castanopsis sclerophylla seeds in a drying oven, and drying for 45min at the temperature of 120 ℃;

(d12) and (d11) parching the semen Castanopsis Sclerophyllae in sand at 100 deg.C for 8min to obtain the final product.

(d22) adding a proper amount of salt into the boiler in the step (d21), and boiling at 100 ℃ for 60 min;

(d23) draining semen Castanopsis Sclerophyllae after cooking, and oven drying in oven at 120 deg.C for 45 min;

(d24) and (d23) parching the semen Castanopsis Sclerophyllae in sand at 100 deg.C for 8min to obtain salty semen Castanopsis Sclerophyllae product.

(d32) adding a proper amount of crystalline sugar powder into the boiling pot in the step (d31), and boiling at 100 ℃ for 60 min;

(d33) draining semen Castanopsis Sclerophyllae after cooking, and oven drying in oven at 120 deg.C for 45 min;

(d34) and (d33) parching the semen Castanopsis Sclerophyllae in sand at 100 deg.C for 8min to obtain the final product.

placing the semen Castanopsis Sclerophyllae raw material in a drying oven, and drying at 80 deg.C until the dry weight ratio of semen Castanopsis Sclerophyllae raw material is 80%.

(C) heating each volumetric flask added with the ferric iron solution in a water bath at the temperature of 80 ℃ for 20min, and then cooling to room temperature;

(D) respectively adding 8mL of o-diazophenanthrene buffer solution into each volumetric flask cooled to room temperature, fixing the volume of the scale mark of the volumetric flask by using distilled water, standing for 10min, and measuring the absorbance of the solution in each volumetric flask at 505 nm;

y＝0.1535x+0.2472(R²＝0.9987)，

putting 25g of the processed castanopsis sclerophylla seeds into a wall-breaking food machine, adding 175g of distilled water into the wall-breaking food machine, and grinding to obtain castanopsis sclerophylla seed stock solution with a grinding material ratio of 1:9, wherein the grinding time is 30 s;

(ii) transferring the castanopsis sclerophylla seed stock solution into a beaker, and soaking for 2h in a water bath at 40 ℃;

(v) placing the volumetric flask added with the ferric iron solution in a water bath at 80 ℃ for heating for 20min, and then cooling to room temperature;

(vi) adding 8mL of o-diazophenanthrene buffer solution into the volumetric flask cooled to room temperature, fixing the volume of the volumetric flask to the scale mark by using distilled water, and standing for 10 min;

the calculation formula of the deacidification rate is as follows,

the concentration of the phenanthroline buffer solution is 0.015 mol/L;

The concentration of the ferric iron solution is 0.01 mol/L;

The experimental method comprises the following steps:

1. drawing of tannic acid standard curve

Preparing a standard solution: accurately weighing 5mg of tannic acid, dissolving, placing in a 50mL volumetric flask, and diluting to constant volume with distilled water to obtain 0.1mg/mL tannic acid standard solution. Putting 0 mu L, 400 mu L, 800 mu L, 1200 mu L, 1600 mu L and 2000 mu L of standard solutions into 6 25mL volumetric flasks, adding 2.5mL of ferric iron solution, heating in 80 ℃ water bath for 20min, cooling to room temperature, adding 8mL of o-phenanthroline buffer solution, diluting to constant volume with distilled water, standing for 10min, and measuring absorbance at 505 nm. The standard curve is plotted with the absorbance on the vertical axis and the tannin concentration on the horizontal axis as shown in FIG. 1, and the value of y is 0.1535x +0.2472 (R)²＝0.9987)。

2. Method for measuring content of tannic acid in castanopsis sclerophylla seeds

Weighing 25g of castanopsis sclerophylla seeds (oven drying at 80 deg.C till the mass is constant to obtain a castanopsis sclerophylla seed raw material with a dry weight ratio of 80%), adding 175g of distilled water, grinding in a wall breaking food machine for 30s to obtain a castanopsis sclerophylla seed raw liquid with a grinding material ratio of 1:9, completely transferring the castanopsis sclerophylla seed raw liquid into a beaker, soaking in a water bath at 40 deg.C for 2h to sufficiently dissolve tannic acid into the distilled water, performing vacuum filtration, and retaining the filtrate to obtain a raw liquid to be detected. Taking 0.5mL of stock solution to be measured into a 25mL volumetric flask, adding 2.5mL of ferric iron solution, heating in water bath at 80 ℃ for 20min, cooling to room temperature, adding 8mL of o-phenanthroline buffer solution, fixing the volume with distilled water, standing for 10min, adding distilled water for diluting by 10 times, measuring absorbance at 505nm, and substituting the value into a standard curve to obtain the concentration of tannic acid in the dilution of the semen Castanopsis Sclerophyllae stock solution. Similarly, the content of tannic acid remained in the deastringent processed semen Castanopsis Sclerophyllae after soaking and rinsing for 10min is also measured by the same method.

The calculation formula of the content of the tannic acid in the castanopsis sclerophylla seeds of the dry weight of the raw materials is as follows:

after subsequent deastringency treatment, the calculation formula of the deacidification rate is as follows:

3. sensory evaluation of Castanopsis sclerophylla seeds

The sensory evaluation standard of the test refers to the regulation of sensory requirements in general rules of roasted nuts and nuts (GBT 22165-2008).

3.1 sensory evaluation of original Castanopsis sclerophylla seed

Inviting 10 food specialties, a research student with basic sensory evaluation knowledge, wherein the ratio of male to female is 1:1, carrying out sensory evaluation on castanopsis sclerophylla seeds subjected to tannin removal treatment and baking and frying under the condition of the same preparation method (original taste) (three aspects of bitter degree, fragrant feeling and mouthfeel), randomly numbering the castanopsis sclerophylla seeds with the same quantity and similar total quality into a plurality of same plastic trays, rinsing the castanopsis sclerophylla seeds with clean water after each group of samples are tasted by a sensory evaluation member, and tasting the next group at intervals of 2 minutes to obtain a sensory evaluation result. The sensory rating criteria for the original taste are shown in table 1. The original taste castanopsis sclerophylla seeds can most visually reflect the change of the bitter degree after the treatment of the dehydrotannic acid, so most sensory evaluation personnel are selected.

Table 1: original taste castanopsis sclerophylla sensory evaluation table

3.2 sensory evaluation of salty Castanopsis sclerophylla seeds

Inviting 5 food professional researchers with basic sensory evaluation knowledge as sensory evaluation personnel, strictly following the requirements of sensory evaluation tests in the evaluation process, randomly numbering the castanopsis sclerophylla seeds which are same in quantity and similar in total mass and are cooked by different salt concentrations, putting the castanopsis sclerophylla seeds into a plurality of same plastic trays, rinsing the mouth with clear water after each group of tasting by the sensory evaluation personnel, tasting the next group at intervals of 2 minutes, and scoring according to the standard of table 2.

Table 2: sensory evaluation table for salty castanopsis sclerophylla seeds

3.3 sensory evaluation of Castanopsis sclerophylla

The sensory evaluation personnel were 5 evaluators having basic sensory evaluation knowledge, and strictly followed the requirements of the sensory evaluation test during the evaluation. Randomly numbering the castanopsis sclerophylla seeds with the same quantity and the similar total mass into a plurality of same plastic white trays, rinsing the mouth with clear water after tasting one group by sensory evaluation personnel, tasting the next group at intervals of 2 minutes, and grading according to the standard of table 3.

Table 3: sensory evaluation table for sweet castanopsis sclerophylla seeds

4. Castanopsis sclerophylla seed tannin content determination result

Three replicates of each replicate were performed, and the results are shown in table 4. As can be seen from the table, the RSD value is less than 3%, and the data is accurate. Calculating the average value of 290.40 μ g/mL of three times of repeated tests, weighing 25g of semen Castanopsis Sclerophyllae fruit, treating to obtain 180mL of semen Castanopsis Sclerophyllae stock solution, diluting by 10 times, and obtaining semen Castanopsis Sclerophyllae tannin content of 2.61% without deacidification treatment. The content of tannin in acorn of Fagaceae is 0.26-17.74%. The content of the castanopsis sclerophylla seed tannic acid obtained by the test is influenced by the raw materials, the extraction mode of the tannic acid, the extraction time and temperature and the determination method of the tannic acid, so that the deviation exists. In order to ensure the accuracy of the measurement result, the content of the tannic acid measured after the castanopsis sclerophylla seeds are treated by the same test reagent according to the same test steps, so that other variables are not introduced.

Table 4: castanopsis sclerophylla seed raw liquor tannin content determination table

5. Optimum debranning process exploratory test

5.1 Single factor test of the Effect of different soaking times on tannin removal

Under the conditions that the temperature of the soaking water is 50 ℃ and the material-to-liquid ratio is 1:9, the influence of different soaking times on the removal rate of the castanopsis sclerophylla seed tannic acid is compared. As shown in FIG. 2, it is understood from FIG. 2 that the removal rate of tannic acid is increased and then kept gentle as the soaking time is increased, and the best removal effect of tannic acid is achieved at 3 hours, and then the removal rate of tannic acid is decreased as the soaking time is increased. The temperature rises in a certain range and is favorable for removing tannic acid, the tannic acid contains a large amount of phenolic hydroxyl groups, has strong reducibility, is poor in thermal stability and high in requirement on temperature, when the temperature exceeds a certain range, the tannic acid can be subjected to denaturation reaction to be converted into other substances with higher reducibility, and can react with second-order iron more easily, so that castanopsis sclerophylla seeds subjected to tannin removal treatment are measured by using a 1, 10-phenanthroline-iron (III) complex spectrophotometry, and the measured value is increased.

5.2 Single factor test of the Effect of different soaking temperatures on tannin removal

Under the conditions that the soaking time is 2h and the material-liquid ratio is 1:9, the influence of different soaking temperatures on the removal rate of the castanopsis sclerophylla seed tannic acid is compared. As shown in fig. 3, it can be seen from fig. 3 that the removal rate of tannic acid is increased to 40 ℃ to reach the optimum value with the soaking temperature, and the removal rate of tannic acid is decreased after the temperature is over the optimum value, because the starch in castanopsis sclerophylla seed starts to be gelatinized when the temperature is over 65 ℃ in addition to the instable and easily damaged heated structure of tannic acid, so that the starch is denatured, and the removal rate of tannic acid is decreased, so the extraction temperature is not suitable to be too high.

5.3 Single factor test of the Effect of different soaking liquors on tannin removal

And comparing the influence of different soaking liquid ratios on the removal rate of the tannic acid under the conditions that the soaking temperature is 50 ℃ and the soaking time is 2 hours. As shown in FIG. 4, it is understood from FIG. 4 that the tannin removing effect increases with the decrease of the feed liquid ratio, and becomes stable after reaching 0.05(1:19), and the effect does not increase with the increase of the immersion solution, because the amount of tannin dissolved increases with the increase of the water of the immersion solution, and when the amount of the aqueous solution reaches a certain value, the tannin is dissolved to be saturated, and the amount of tannin dissolved to be added to the aqueous solution does not increase, and other impurities are more likely to be eluted, which may affect the measurement result. However, the removal rate of tannic acid does not have a large difference under different material-liquid ratios in general, because the content of tannic acid in the castanopsis sclerophylla seeds is not high enough to be saturated. The soaking solution can be added to dissolve more tannic acid under the same time condition, and can be obtained from Noyes-Whitney equation dC/dt ═ kDA (Cs-Ct), when kD-dissolution rate constant and Cs-drug saturation solubility are not changed, the solution is added to make more Castanopsis sclerophylla seeds directly soaked in the solution to increase surface area A, and the drug concentration Ct is reduced to increase dissolution rate dC/dt. Therefore, more tannic acid can be dissolved in the same time due to faster dissolution rate. In order to implement the concept of saving environment, under the condition that the removal rate of the tannic acid is constant, a higher feed-liquid ratio can be selected, and water resources are saved.

5.4 orthogonal testing of the influencing factors for tannin removal Rate

According to the results of the single-factor test, the soaking temperature is selected to be 30 ℃ and 40 ℃ with the best effect, the material-liquid ratio is selected to be 1:19 and 1: 24, soaking time conditions were selected to be 2 hours and 3 hours, and orthogonal test table 5 was designed, and the test results are shown in table 6. The experimental results can obtain the main factors and the secondary factors: the time is more than the temperature and the material-liquid ratio is more than the temperature, namely the time and the temperature which have the most obvious effect on the removal effect of the castanopsis sclerophylla seed tannic acid have the least effect, which is consistent with the result presented in the single-factor test. And the optimal condition combination of the deacidification is obtained as follows: 2h, 40 ℃, 1:19, the removal rate of the tannic acid reaches 67.08 percent.

Table 5: orthogonal test table

Factors of the fact	Time/h	Temperature/. degree.C	Ratio of material to liquid
				Experiment
1	2	30	1：19
				Experiment 2	2	40	1：24
Experiment 3	3	30	1：24
				Experiment 4	3	40	1：19

Table 6: visual analysis meter

Factors of the fact	Time/h	Temperature/. degree.C	Ratio of material to liquid	Tannin removal rate (%)
					Experiment 1	1	30	1：19	0.58
Experiment 2	1	40	1：24	0.60
					Experiment 3	2	30	1：24	0.28
Experiment 4	2	40	1：19	0.47
					Mean value 1	0.590	0.450	0.545
Mean value 2	0.375	0.575	0.480
					Extreme difference	0.275	0.125	0.065

6. Sensory evaluation verification experiment

Comparing the control semen Castanopsis Sclerophyllae before astringency removal with the test semen Castanopsis Sclerophyllae after astringency removal according to sensory evaluation method and sensory evaluation table 1, wherein the sensory evaluation results of the two are shown in table 7, and the radar chart is shown in fig. 5. The comprehensive score of the test castanopsis sclerophylla seeds is 55.4 points and 13.5 points higher than that of the control castanopsis sclerophylla seeds, and the score of the degree of bitterness is obviously higher than that of the control group. In terms of flavor score and mouthfeel, the experimental group and the control group have no great difference, and the treatment of the dehydrotannic acid has small influence on flavor and mouthfeel.

Table 7: sensory evaluation results Table

7. Castanopsis sclerophylla seed baking and frying process

7.1 preparation method of semen Castanopsis Sclerophyllae

Tannin removal treatment → cleaning → draining → oven drying (120 ℃, 45min) → sand-frying (100 ℃, 8 min).

7.2 preparation method of salty semen Castanopsis Sclerophyllae

(1) Process flow

Tannin removal treatment → cleaning → seasoning boiling (100 ℃, 60min) → draining → oven drying (120 ℃, 45min) → sand-frying (100 ℃, 8 min).

(2) Sensory evaluation of cooking salt content

The evaluation results are shown in Table 8. The result shows that the salt content is 14% (namely boiling 100g castanopsis sclerophylla seed, adding 14g salt, adding 100mL water) and the taste is best, and when the total sensory evaluation score is 75 minutes, the total sensory evaluation score can reach 60.4 minutes.

Table 8: sensory evaluation result of salty castanopsis sclerophylla

7.3 preparation method of semen Castanopsis Sclerophyllae

(1) Process flow

(2) Organoleptic evaluation of content of boiled white granulated sugar

The evaluation results are shown in Table 9. The result shows that the content of the crystal sugar powder is 40% (40 g of crystal sugar powder put into boiled 100g of castanopsis sclerophylla) and the taste is best, and when the total sensory evaluation score is 75 minutes, the total sensory evaluation score can reach 61.6 minutes.

Table 9: sensory evaluation result of semen Castanopsis Sclerophyllae

8. Summary of the invention

The invention determines that the method for measuring the tannin which is a substance causing the castanopsis sclerophylla seeds to be bitter and astringent is a 1, 10-phenanthroline-iron (III) complex spectrophotometry, and experiments prove that the warm water leaching can achieve better effect of removing the tannin. Finally, the process of the castanopsis sclerophylla leisure food is determined, and the castanopsis sclerophylla leisure food can be finally obtained with better taste through the processes of deacidification, seasoning boiling, cleaning, oven drying and sand frying.

The invention obtains the following effective effects:

(1) the content of Castanopsis Sclerophylla seed tannin which is not treated with debranning acid is 2.61% by 1, 10-phenanthroline-iron (III) complex spectrophotometry. Based on the data, a method for removing astringent taste of the castanopsis sclerophylla seeds, namely a warm water soaking method is established, and the method is quicker and more convenient than the traditional method for soaking for a long time. By a warm water immersion method, single-factor tests and orthogonal tests on time, temperature and material-liquid ratio prove that the temperature of distilled water is 40 ℃, the material-liquid ratio is 1: soaking for 2h under the condition of 19 ℃ to ensure that the deacidification rate reaches 67.08 percent. Wherein, the most significant factors influencing the tannin removing rate are time, temperature and material-liquid ratio in turn. Although the castanopsis sclerophylla seeds still have 1.4% of tannic acid residue, in a sensory evaluation test, the degree of bitterness of the castanopsis sclerophylla seeds is evaluated from ' bitterness and astringency at the entrance before tannin removal treatment is obvious and unacceptable ' no bitterness and astringency at the entrance after tannin removal is acceptable ', the fact that the bitterness and astringency of the castanopsis sclerophylla seeds are obviously weakened due to the removal of tannic acid proves that the removal of 67.08% of tannic acid has a certain effect on the reduction of astringency is proved, and the sensory evaluation test also proves that the influence of the tannin removal treatment on the fragrance and the taste is small.

(2) The seasoning, formula and frying process of the castanopsis sclerophylla seeds are determined, and the original taste and seasoning (spiced salt and sweet taste) roasted and fried castanopsis sclerophylla seed products are developed. The original taste, salty taste and the roasted and fried product of the castanopsis sclerophylla seeds are subjected to four steps of tannin removal treatment, cleaning, oven drying (120 ℃, 45min) and sand frying (100 ℃, 8min), wherein the salty castanopsis sclerophylla seeds need to be added with salt water with the mass concentration of 14 percent, the sweet castanopsis sclerophylla seeds need to be added with crystal sugar powder with the content of 40 percent, and the castanopsis sclerophylla seeds are boiled for 60min under the condition of 100 ℃ after the tannin removal and cleaning, drained, dried and sand fried. Wherein, when the sensory scores of the degree of bitterness and astringency, seasoning and mouthfeel are divided into 75 minutes, the sweet castanopsis sclerophylla seeds can reach 61.6 minutes, and the score is the highest and is most easily accepted by evaluators.

Claims

1. The processing method of the castanopsis sclerophylla seeds is characterized in that: comprises the following steps of (a) carrying out,

2. The processing method of castanopsis sclerophylla seeds according to claim 1, which is characterized in that: the preparation method of the original taste castanopsis sclerophylla seed product comprises the following steps,

3. The processing method of castanopsis sclerophylla seeds according to claim 1, which is characterized in that: the preparation method of the salty castanopsis sclerophylla seed product comprises the following steps,

4. The processing method of castanopsis sclerophylla seeds according to claim 1, which is characterized in that: the preparation method of the sweet castanopsis sclerophylla seed product comprises the following steps,

5. The processing method of castanopsis sclerophylla seeds according to claim 1, which is characterized in that: the castanopsis sclerophylla seed in the step (a) is processed by the following steps,

6. The processing method of Castanopsis sclerophylla seed according to claim 5, which is characterized by comprising the following steps: the drawing of the standard curve of the monopenin in the castanopsis sclerophylla seeds comprises the following steps,

(A) weighing a proper amount of tannic acid, taking a volumetric flask with a proper specification, adding tannic acid into the volumetric flask, and fixing the volume to the scale mark of the volumetric flask by using distilled water to prepare a tannic acid standard solution of 0.1 mg/mL;

y＝0.1535x+0.2472，

wherein x represents the concentration of tannic acid, y represents the absorbance, and the correlation coefficient R of the equation²＝0.9987。

7. The processing method of Castanopsis sclerophylla seed as claimed in claim 6, which is characterized by comprising: the method for measuring the content of the tannic acid in the castanopsis sclerophylla seeds comprises the following steps,

putting a proper amount of the castanopsis sclerophylla seeds after treatment into a broken-wall food machine, adding a proper amount of distilled water into the broken-wall food machine for grinding to obtain castanopsis sclerophylla seed stock solution with the grinding material ratio of 1:9, wherein the grinding time is 20-40 s;

8. The processing method of castanopsis sclerophylla seed according to claim 7, which is characterized in that: the calculation formula of the content of the tannic acid in the castanopsis sclerophylla seeds of the dry weight of the raw materials is as follows,

the calculation formula of the deacidification rate is as follows,

9. the processing method of castanopsis sclerophylla seed according to claim 6 or 7, which is characterized in that: the concentration of the phenanthroline buffer solution is 0.015 mol/L;

the preparation method of the phenanthroline buffer solution with the concentration of 0.015mol/L comprises the steps of taking 1.487g of 1, 10-phenanthroline, dissolving the 1, 10-phenanthroline in distilled water, placing the solution in a 500mL volumetric flask, and fixing the volume to the scale mark of the volumetric flask by using the distilled water.

10. The processing method of castanopsis sclerophylla seed according to claim 6 or 7, which is characterized in that: the concentration of the ferric iron solution is 0.01 mol/L;

the preparation method of the ferric iron solution with the concentration of 0.01mol/L comprises the steps of taking 2.51g of ferric ammonium sulfate dodecahydrate, dissolving the ferric ammonium sulfate dodecahydrate by using distilled water, adding 0.5mL of concentrated sulfuric acid into the dissolved solution, transferring the solution into a 500mL volumetric flask, and fixing the volume to the scale mark of the volumetric flask by using the distilled water to obtain the ferric iron solution.