CN102084894A - Chinese chestnut brown stain preventing processing technology - Google Patents

Abstract

The invention discloses a Chinese chestnut brown stain preventing processing technology which comprises the following steps of: 1, screening Chinese chestnuts; 2, processing at low temperature; 3, processing with CO2: putting the Chinese chestnuts in an environment with the CO2 concentration of 5-30 percent (volume) and temperature of 10-20 DEG C and relative humidity of 85-95 percent for 2-20 days; 4, carrying out gas stifling treatment on the Chinese chestnuts by adopting ethylene or alcohol; 5, removing hulls and red skins; 6, inactivating enzyme: putting Chinese chestnut kernels in food-grade acidic liquid with the temperature of 80-100 DEG C or food-grade acidic stream with the temperature of 100-110 DEG C, and controlling the pH value of the liquid or stream to be 1-6 and the processing time to be 5-20min; 7, curing: putting the Chinese chestnut kernels into food-grade alkali liquid with pH value of 7-12 at a temperature of 90-100 DEG C, and processing for 5-20min; 8, bagging and sealing; 9, sterilizing with back pressure at high temperature and high pressure; and 10, cooling to normal temperature for storing. The Chinese chestnuts processed by using the technology maintain the special grain flavor and the sweetness while keeping the natural yellow color, and is best in color, favor and taste.

Description

Anti-browning Processing Technology of Chestnut

technical field

The invention relates to the technical field of food processing, in particular to a processing method capable of preventing browning of chestnuts.

Background technique

Chestnut is one of the special dried fruits in China, especially the chestnut in northern China, which has excellent color, fragrance, taste, and shape. It has a very high market share in Japan and South Korea, and the demand is also increasing year by year. According to data, the current global annual output of chestnuts is about 700,000 to 800,000 tons, and the annual output of Chinese chestnuts accounts for about 60% of the global total output of chestnuts. However, the global annual demand for chestnuts is more than 2 million tons, and the market gap is very large. . Since the overall output of chestnuts in China is still far from enough, the markets in Western Europe and North America have hardly been developed, so their market prospects are very broad.

However, chestnuts are prone to browning during processing. Currently, the chestnut kernels in vacuum or air-filled small packages on the market are all dark brown, and the appearance of the product is poor. Browning leads to nutrient loss and reduced bioavailability such as anti-oxidation.

Chestnut browning includes enzymatic browning and non-enzymatic browning. Enzymatic browning is a color change caused by the oxidation of phenols and tannins in chestnuts caused by polyphenol oxidase (PPO) and peroxidase (POD). Refined. Non-enzymatic browning is mainly Maillard (Maillard) reaction, ascorbic acid oxidation and browning caused by metal ions.

In recent years, scientific research workers have mainly used color protection solution to prevent browning of chestnut browning control, and the formula of color protection solution is mainly sulfur-containing formula, and there are few formulas of non-sulfur color protection solution. Due to the potential harm of sulfur-containing substances to the human body, countries around the world have gradually restricted the use of sulfur-containing color protection liquid formulations, and non-sulfur, safe color protection liquid formulations have become a development trend. For this reason, Chinese invention patent CN101406212A discloses a kind of method of controlling the browning of chestnut, the Chinese chestnut after the peeling is dropped into and soaked in the non-sulfur color-protecting liquid prepared, and this color-protecting liquid is tea polyphenol, kojic acid, L - Gudanganfu or L-tartaric acid, or a combination of all of the above; after soaking, rinse off the color protection solution on the chestnut surface with clean water.

Though the color protecting liquid that above-mentioned method uses does not contain sulfur, there is following shortcoming:

(1) When high-temperature sterilization is not carried out, the shelf life of chestnuts processed by this method does not exceed 3 to 5 days. After complete sterilization at 121°C and 30 minutes, the browning is still serious and the original color cannot be maintained; (2) Processed chestnut products The flavor deteriorates and loses the unique aroma and taste of chestnut.

Contents of the invention

The technical problem to be solved by the present invention is to provide a natural chestnut anti-browning processing technology that can prevent the chestnut from browning, maintain its golden color, and maintain the original grain fragrance and sweet flavor of the chestnut.

For this reason the technical scheme of the present invention is as follows:

A kind of anti-browning processing technology of chestnut, comprises the following steps:

1) Screening of chestnuts: select fruits with plump flesh and full maturity to remove various impurities;

2) Low-temperature treatment: at an ambient relative humidity of 80% to 95%, the temperature of the chestnut is controlled to drop by 1 to 2°C every day until the temperature of the chestnut drops to 0 to 1°C;

3) _CO2 treatment: the chestnut after step 2) is placed in _CO2 concentration is 5%～30% (volume percentage), temperature 10～20 ℃, in the environment of relative humidity 85%～95%, time is 2 ~20 days;

4) Gas fumigation treatment: adopt one or both of ethylene and ethanol to fumigate the chestnut after step 3) treatment, wherein the ethylene concentration is 0.5-1.5 mg/kg, ethanol 5%-10%, and the temperature 15～25℃, relative humidity 85%～95%, when ethanol or ethylene is used alone, the fumigation treatment time is 1～4 days; sky;

5) Remove the shell and red coat to obtain chestnut kernels;

6) Enzyme-killing treatment: place chestnut kernels in acidic food slurry or food-grade acidic liquid at 80-100°C, or in food-grade acidic steam at 100-110°C, and control the pH of the liquid or steam to 1-100°C. 6. The processing time is 5-20 minutes;

7) Curing treatment: Put the chestnut kernels treated in step 6) into a food-grade alkaline liquid with a pH value of 7-12 at 90-100°C for 5-20 minutes;

8) Packing and sealing;

9) High temperature, high pressure, and back pressure sterilization: Sterilize at a temperature of 115-130°C and a pressure of 1-2kg/ ^cm2 for 10-40 minutes;

10) Store under cooling and normal temperature conditions.

Preferably, the CO ₂ concentration in step 3) is 10%-15% (volume percentage), and the treatment time does not exceed 8-10 days.

Preferably, when ethanol or ethylene are used alone in step 4), the gas fumigation time is 2 days.

Preferably, the step 6) also includes the steps of repairing the damage of the fruit, polishing and grinding and removing the pulp of diseases and insect pests.

In the above method, the acidic food slurry is an aqueous solution of agricultural products or plant slurry, and the food-grade acidic liquid is an aqueous solution of inorganic or organic acidic substances or an aqueous solution containing acidic substances produced by microbial metabolism.

Preferably, the pH value of the enzyme killing treatment in step 6) is 3-5, and the time is 6-10 minutes.

In the above method, the food-grade alkaline liquid described in step 7) is an aqueous solution of inorganic or organic alkaline substances, the pH value of the solidification treatment is 8-9, and the time is 6-10 minutes.

In the processing method of the present invention, the fruit is fully ripened by low-temperature treatment of chestnuts, thereby regulating the color, fragrance and taste of the fruit to an optimal value; by using CO ₂ The fruit is processed to promote the saccharification of the fruit; by using ethylene, Fumigation of chestnuts with ethanol not only improves the saccharification degree of chestnuts and the valley flavor of chestnuts, but also prevents the browning reaction of chestnuts during processing. The chestnut kernel processed by the method of the present invention maintains its unique grain flavor and sweet taste while maintaining the natural color of the chestnut, so that the color, fragrance and taste are all excellent.

Detailed ways

The processing method of the present invention will be described in detail below.

Chestnut anti-browning processing method of the present invention comprises the following steps:

(1) Screening of chestnuts. Choose fruits with high sugar and starch content, full flesh and full maturity, remove diseases, insects, mildew, and shriveled fruits, grade them, and remove various impurities.

(2) Carry out low-temperature treatment to the screened chestnuts: control the temperature of the chestnuts to drop by 1-2°C every day, store them for a long time when the temperature of the chestnuts drops to 0-1°C, and control the relative humidity of the environment to be 80%-95% all the time.

(3) carry out _CO to the Chinese chestnut after step (2) treatment: _CO treatment concentration 5%～30% (volume percentage, the same below), temperature 10～20 ℃, relative humidity 85%～95%, time 2 ~20 days. Among the above conditions, it is preferred that the _CO2 concentration is 10% to 15%, and the treatment time is not more than 8 to 10 days, for example, at 20°C, for _CO2 with a concentration of 15%, the treatment time is not more than 8 days, and the concentration 10% CO ₂ , the treatment time does not exceed 10 days.

(4) Gas fumigation treatment: adopt one or both of ethylene and ethanol to fumigate the chestnut after step 3) treatment, wherein the ethylene concentration is 0.5～1.5mg/kg, ethanol 5%～10%, temperature 15～25℃, relative humidity 85%～90%, when ethylene and ethanol are used alone, the treatment time is 1 to 4 days, and the optimal treatment time is 2 days; Same, however, processing time 1-2 days.

Fumigation treatment is beneficial to improve the flavor of chestnut with skin and prevent the pulp from browning. Fumigation treatment not only improves the saccharification degree of chestnut, improves the fruit flavor, but also prevents enzymatic and non-enzymatic browning in the process of processing.

Preferably, when the ethylene concentration is 1 mg/kg and the ethanol concentration is 8% (volume percentage), the treatment effect is the best when fumigated for 1 day at a temperature of 20°C and a relative humidity of 90%.

When fumigated with ethylene gas alone, it is preferred that the ethylene concentration is 1 mg/kg, the temperature is 20° C., the relative humidity is 90%, and the treatment time is 2 days.

When using ethanol gas alone for fumigation, the preferred conditions are: 6% ethanol, 20°C temperature, 90% relative humidity, and 2 days of treatment time.

(5) Remove the shell and red coat to obtain the chestnut kernel, and perform plastic treatment to improve its quality and color. Either mechanical or manual methods can be used for shelling and red coat removal. After shelling and removing the red coat, it is best to refrigerate for a short time at -1~0°C or freeze for a long time at -20~-10°C. Among them, the quality preservation effect is better at -18～-15°C.

The shaping treatment includes repairing fruit damage, polishing and grinding to remove grooves, and removing pulp from diseases and insect pests. Shaping can be done manually or mechanically. If it is a low-temperature plastic treatment, the shelled and red-coated fruits are damaged and repaired, and the pulp of diseased insects is removed, and then quick-frozen to -18~-20°C, and then polished to remove grooves and plastic.

(6) Enzyme killing: put chestnut kernels in food-grade acidic liquid at 80-100°C or food-grade acidic steam at 100-110°C, and control the pH of the liquid or steam to 1-6. It depends on the length of high-temperature treatment time, and the general treatment time is 2 to 20 minutes. Preferably, the pH value is 3-5, and the high temperature treatment is carried out for 6-10 minutes.

The food-grade acidic liquid is an aqueous solution of agricultural products or plant slurries, an aqueous solution of inorganic or organic acidic substances or an aqueous solution containing acidic substances produced by microbial metabolism. For example, it can be an aqueous solution added with agricultural products, freshly squeezed juice of plants, leaching juice, an aqueous solution containing its slurry and fragments; it can also be an aqueous solution of lactic acid solution or other inorganic or organic acidic substances.

(7) Curing: put the chestnut kernels treated in step 6) into a food-grade alkaline liquid with a pH value of 7-12 at 90-100°C for 2-10 minutes. It is preferred to treat for 6-10 minutes under the condition that the pH value is 8-9. It is best to wash with potable water after curing.

Described food-grade alkaline liquid can be the aqueous solution of sodium bicarbonate, calcium bicarbonate, also can be the aqueous solution of alkaline substances such as carboxylate, amine (as triethylamine, piperidine), pyridine, quinoline, or It is an aqueous solution of alkaline substances such as other agricultural products and plants, as long as the pH value of the solution is 8-9.

(8) Packing: Aluminum foil bags or conventional high-temperature retort bags can be used, _N2 filled or vacuum packed.

(9) High temperature, high pressure, and back pressure sterilization: Sterilize at a temperature of 115-130°C and a pressure of 1-2kg/cm ² for 10-40 minutes. A preferred temperature is 120-125°C, and a more preferred temperature is 121°C.

After the chestnut kernels processed by the above method are cooled to normal temperature, they can be preserved at normal temperature for more than 12 months.

Claims (10)

1. a chestnut anti-browning processing technology, comprises the following steps: 1) Screening of chestnuts: select fruits with plump flesh and full maturity to remove various impurities; 2) Low temperature treatment: under the relative humidity of the environment of 80% to 95%, the temperature of the chestnut is controlled to drop by 1 to 2°C every day until the temperature of the chestnut drops to 0 to 1°C, and it is kept at this temperature to keep fresh; 3) _CO2 treatment: the chestnut after step 2) treatment is placed in _CO Concentration is 5%～30% (volume percentage), in the environment of temperature 10～20 ℃, relative humidity 85%～95%, treatment time is 2-20 days; 4) Gas fumigation treatment: adopt one or both of ethylene and ethanol to fumigate the chestnut after step 3) treatment, wherein the ethylene concentration is 0.5-1.5 mg/kg, ethanol 5%-10%, and the temperature 15-25°C, relative humidity 85%-95%, when ethanol or ethylene is used alone, the fumigation treatment time is 1-4 days; when used in combination, the concentration is the same as when used alone, and the treatment time is 1-2 days; 5) Shelling and removing the red coat to obtain chestnut kernels; 6) Enzyme-killing treatment: place the chestnut kernels in step 5) in acidic food slurry or food-grade acidic liquid at 80-100°C or in food-grade acidic steam at 100-110°C, and control the liquid or steam The pH value is 1-6, and the treatment time is 5-20 minutes; 7) Curing treatment: at 90-100°C, put the chestnut kernels treated in step 6) into a food-grade alkaline liquid with a pH value of 7-12, and the treatment time is 5-20 minutes; 8) Packing and sealing; 9) High temperature, high pressure, and back pressure sterilization: Sterilize at a temperature of 115-130°C and a pressure of 1-2kg/ ^cm2 for 10-40 minutes; 10) Store under cooling and normal temperature conditions. 2. The chestnut anti-browning processing technology according to claim 1, characterized in that: in step 3), the _CO2 concentration is 10% to 15% (volume percentage), and the treatment time is 8 to 10 days. 3. The chestnut anti-browning processing technology according to claim 1 is characterized in that: when ethanol or ethylene are used alone in step 4), the fumigation treatment time is 2 days. 4. The chestnut anti-browning processing technology according to claim 1, characterized in that: after shelling and red coat removal in step 5), chestnut kernels are refrigerated at -1 to 0°C or frozen at -20 to -10°C Tibetan. 5 . The chestnut anti-browning processing technology according to claim 1 , is characterized in that: before the step 6), it also includes the steps of repairing the damage of the fruit, polishing and grinding and removing the pulp of diseases and insect pests. 6. The chestnut anti-browning processing technology according to claim 1, characterized in that: the acidic food slurry in step 6) is an aqueous solution of agricultural products or plant slurry, and the food-grade acidic liquid or steam is inorganic or organic acidic An aqueous solution of a substance or an aqueous solution containing acidic substances produced by microbial metabolism. 7. The chestnut anti-browning processing technology according to claim 1 or 6, characterized in that: in step 6), the pH value of the enzyme-killing treatment is 3-5, and the treatment time is 6-10 minutes. 8. The chestnut anti-browning processing technology according to claim 1, characterized in that: the food-grade alkaline liquid described in step 7) is an aqueous solution of inorganic or organic alkaline substances. 9. The chestnut anti-browning processing technology according to claim 1 or 7, characterized in that: the pH value of the solidification treatment in step 7) is 8-9, and the treatment time is 6-10 minutes. 10. The chestnut anti-browning processing technology according to claim 1, characterized in that: the packaging bag adopted in step 8) bagging is an aluminum foil bag or a conventional high-temperature cooking bag, filled with N ₂ packaging or vacuum packaging.