CN105594845A - Novel cassava color-protection fresh-keeping agent, and fresh keeping method - Google Patents

Abstract

The present invention relates to a kind of cassava color-protecting antistaling agent and fresh-keeping method thereof, and the composition of described antistaling agent comprises deionized redistilled water and two or three kinds in following three kinds of components: (A) chitosan, One or two or three of sodium alginate and konjac glucomannan; (B) one or two of citric acid and ascorbic acid; (C) calcium chloride. The cassava color-preserving and fresh-keeping agent of the invention is used for fresh-keeping, which can effectively prevent cassava from browning and rotting after harvesting, maintain good storage quality of cassava, and prolong the storage and fresh-keeping time.

Description

Novel cassava color-protecting and fresh-keeping agent and fresh-keeping method thereof

technical field

The invention relates to a fresh-keeping agent and its application in cassava fresh-keeping, and relates to the field of food fresh-keeping.

Background technique

Cassava (Manihotesculenta Crantz) belongs to Euphorbiaceae (Euphorbiaceae) Cassava plant, is one of the world's three largest potato (cassava, potato, sweet potato). Its root tuber is rich in starch and is an important biomass energy material in tropical and subtropical regions. Due to the crisp and tender tissues of fresh cassava and high water content, "post-harvest physiological deterioration" is prone to occur during processing and storage, resulting in dehydration, browning, and rot of roots, and the storage period of fresh cassava is extremely short (1-2 days). , thereby restricting the supply of cassava on the market in large quantities and its post-production comprehensive utilization, seriously affecting its commodity value.

The traditional storage and preservation methods of cassava mainly include sealing wax, sand burial, trench preservation, etc., which can extend the shelf life of cassava to 2 months, but after storage, cassava roots tend to brown and change taste, making them inedible. In recent years, fresh-keeping materials made of materials such as biopolymers, such as chitosan film and starch film, have been widely used in the field of fruit and vegetable storage due to their non-toxic, degradable and high biocompatibility characteristics, which have significantly improved Fruit and vegetable storage and fresh-keeping effects (“Effects of different coating treatments on the shelf-life quality of potatoes”, Food and Machinery, 2011, 27(3) 122-124), but it is rarely used in the storage and fresh-keeping of fresh cassava .

Contents of the invention

The purpose of the present invention is to make up for the deficiencies of the prior art, and provide a novel cassava color-protecting and fresh-keeping agent and its fresh-keeping method, which can effectively prevent cassava from browning and rotting after harvesting, maintain good storage quality of cassava, and prolong the storage and fresh-keeping time. Using the cassava color-protecting and antistaling agent of the present invention to preserve the freshness of the heat-treated cassava coating film can effectively prolong the cassava storage period and maintain its nutritional value during storage, thereby effectively increasing the commercial value of the cassava and extending the cassava industry chain.

To achieve the above object, the present invention provides the following technical solutions:

A kind of cassava color-protecting and antistaling agent comprises deionized redistilled water and two or three of the following three components in its composition:

(A) one or two or three of chitosan, sodium alginate and konjac glucomannan;

(B) one or both of citric acid and ascorbic acid;

(C) calcium chloride.

Wherein, the preservative does not contain preservatives.

Wherein, the composition of described cassava color-protecting and antistaling agent is deionized redistilled water and two or three kinds in following three kinds of components:

(A) one or two or three of chitosan, sodium alginate and konjac glucomannan;

(B) one or both of citric acid and ascorbic acid;

(C) calcium chloride.

In one embodiment of the present invention, the composition of the preservative is deionized redistilled water, chitosan, ascorbic acid and calcium chloride; or, the composition of the preservative is deionized redistilled water, sodium alginate , ascorbic acid and calcium chloride; or, the composition of the preservative is deionized redistilled water, chitosan, citric acid and calcium chloride; Sodium, citric acid and calcium chloride; Or, the composition of described antistaling agent is deionized heavy distilled water, konjac glucomannan, citric acid and calcium chloride; Perhaps the composition of described antistaling agent is deionized heavy distilled water , Konjac Glucomannan, Ascorbic Acid and Calcium Chloride.

Wherein, the mass percentage of the sum of two or three of the (A), (B) and (C) components is 1-10 wt%, preferably 1-6 wt%.

Wherein, the mass percentage of the (A) component is 1-3 wt%, preferably 1.5-2 wt%. The mass percentage of the (B) component is 0.1-2wt%, preferably 0.15-0.5wt%. The mass percentage of the (C) component is 0.1-0.5 wt%, preferably 0.2-0.4 wt%.

Wherein, preferably, the component and mass percent of described cassava color-protecting and antistaling agent are:

(A) one or two or three of chitosan, sodium alginate and konjac glucomannan, 1-3wt%, preferably 1.5-2wt%;

(B) one or both of citric acid and ascorbic acid, 0.1-2wt%, preferably 0.15-0.5wt%;

(C) calcium chloride, 0.1～0.5wt%, preferably 0.2～0.4wt%;

The remainder was deionized redistilled water.

The present invention also provides the following technical solutions:

A fresh-keeping processing method of cassava, comprising a heat treatment step, a treatment step of the above-mentioned cassava color-protecting and fresh-keeping agent and a vacuum packaging step.

Specifically, the method includes the following technological process: raw material selection→cleaning→peeling→shaping, cutting→heat treatment→treatment with the above-mentioned cassava color-protecting and preservative→air-drying→bagging→vacuum packaging→storage.

The step of selecting raw materials specifically includes: selecting fresh cassava with no mechanical damage, no pests and diseases, and good quality as the raw material.

The steps of cleaning, peeling, shaping and cutting are as follows: removing sediment from the raw materials, washing with running water, peeling, and cutting into shapes suitable for consumption.

The heat treatment step specifically includes: putting the cassava into hot water at 45-80°C for 2-10 minutes, and removing the surface moisture after taking it out.

The preservative treatment and air-drying steps specifically include: placing the heat-treated cassava in the cassava color-protecting preservative, soaking for 5-10 minutes, taking it out and air-drying.

The steps of bagging, vacuum packaging and storage specifically include: placing the cassava in a packaging bag, vacuum packaging, and storing at 15-30°C, preferably 25-28°C.

Wherein, the shape suitable for eating in the described shaping and cutting steps is a block, bar or sheet; wherein, the length of the block is 2-5 cm, and the thickness is 2-5 cm; the length of the bar is 8-10 cm, and the thickness is 2 to 3 cm; the thickness of the sheet is 2 to 4 cm.

Wherein, the temperature in the heat treatment step is preferably 55-70° C., and the time is preferably 4-6 minutes.

Wherein, the moisture on the cassava surface must be completely removed in the heat treatment step.

Wherein, the soaking time in the preservative treatment and air-drying steps is preferably 3-10 minutes, and the volume ratio of cassava to the preservative is 1:2-5 (preferably 1:3).

Wherein, the packaging bag material in the packaging step is polyethylene (PE), polypropylene (PP) or aluminum foil (PT).

Wherein, the degree of vacuum in the packaging step is -0.06MPa˜-0.1MPa.

A kind of cassava color-protecting antistaling agent and fresh-keeping method thereof of the present invention have following beneficial effects:

The cassava produced by the method is a semi-ripe product, which is not only resistant to storage, but also convenient for consumers to pursue convenient and fast life needs.

The present invention combines physical methods with edible polysaccharide composite antistaling agents to inhibit browning of cassava without using any preservatives, thereby not only achieving the purpose of preventing product deterioration, but also ensuring food safety.

The cassava produced by the invention is stored at room temperature for more than 10 days, and its color, flavor and nutritional quality are all kept normal, which not only facilitates storage and transportation, but also helps to increase the commercial value of the cassava.

Description of drawings:

Fig. 1 process flow chart of a novel cassava color-protecting and fresh-keeping method of the present invention

The influence of Fig. 2 preservative on cassava weight loss rate;

The influence of Fig. 3 preservative on cassava hardness;

The influence of Fig. 4 preservative on cassava color and luster;

The influence of Fig. 5 preservative on cassava starch content;

The influence of Fig. 6 preservative on cassava soluble solids (TSS) content;

The influence of Fig. 7 preservative on cassava SOD enzyme activity;

The influence of Figure 8 preservative on cassava POD enzyme activity;

Figure 9 The effect of preservatives on the total phenolic content of cassava.

detailed description

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through different specific implementation modes, and various modifications or changes can be made to the details in this specification based on applications in different aspects without departing from the spirit of the present invention.

Sodium alginate, chitosan, konjac glucomannan, citric acid, ascorbic acid, and calcium chloride are food grade, and reagents such as disodium hydrogen phosphate, thiobarbituric acid, and hydrogen peroxide are domestic analytically pure. Distilled water is deionized redistilled water.

LFRA1500g texture analyzer, American Brookfield Company; CR-400 color difference meter, Japan Minolta Instrument Company; WYT-4 handheld refractometer; GH series high-precision constant temperature water tank, Hannuo Instrument; electronic balance MS104/MS204S Mettler.

Example 1

(1) Select fresh cassava with no mechanical damage, no pests and diseases, and good quality as raw material;

(2) After the raw material is removed from sediment, washed with running water, and peeled, cut into shapes suitable for eating, such as blocks, strips or slices; wherein, the length of the block is 2-5cm, and the thickness is 2-5cm; The length is 8-10cm, the thickness is 2-3cm; the thickness of the sheet is 2-4cm;

(3) Put the cassava into hot water at 55-60°C for 5 minutes, remove the surface moisture after taking it out;

(4) Cassava is placed in the deionized redistilled aqueous solution of 1.5wt% chitosan, 0.15wt% citric acid, 0.25wt% calcium chloride (the volume ratio of cassava and preservative is 1:3), soak 5min, take out after drying;

(5) Put the cassava in a polyethylene bag, vacuum pack (vacuum degree -0.06MPa～-0.1MPa) and store at 25-28°C.

On the 15th day of storage, under the action of heat treatment and preservatives, the cassava root did not undergo browning and rot, and still maintained the original quality, with a light yellow color, good taste, and a sweet potato smell. The relevant quality inspection results are as follows: weight loss rate is 2.0-2.5%, hardness is 0.75-0.85kg/cm ² , L ^* value is 43-49, starch content is 28.5-32.0%, soluble solid content is 2.35-2.65%, total phenols are 8.5- 9.8mg/100g, SOD and POD are 8.5-9.3U/g·FW·h, 21.0-24.0U/g·min, respectively.

Example 2

(1) Select fresh cassava with no mechanical damage, no pests and diseases, and good quality as raw material;

(2) After the raw material is removed from sediment, washed with running water, and peeled, cut into shapes suitable for eating, such as blocks, strips or slices; wherein, the length of the block is 2-5cm, and the thickness is 2-5cm; The length is 8-10cm, the thickness is 2-3cm; the thickness of the sheet is 2-4cm;

(3) Put the cassava into hot water at 65-70°C for 3 minutes, remove the surface moisture after taking it out;

(4) Put cassava in deionized redistilled aqueous solution of 1.5wt% sodium alginate, 0.15wt% ascorbic acid, 0.25wt% calcium chloride (volume ratio of cassava to preservative 1:3), soak for 7min, take out dry;

(5) Put the cassava in a polyethylene bag, vacuum pack (vacuum degree -0.06MPa～-0.1MPa) and store at 25-28°C.

On the 15th day of storage, under the action of heat treatment and preservatives, the cassava root did not undergo browning and rot, and still maintained the original quality, with a light yellow color, good taste, and a sweet potato smell. The relevant quality inspection results are as follows: weight loss rate is 2.0-2.5%, hardness is 0.75-0.85kg/cm2, L* value is 43-49, starch content is 28.5-32.0%, soluble solid content is 2.35-2.65%, total phenols are 8.5-9.8 mg/100g, SOD and POD are 8.5-9.3U/g·FW·h, 21.0-24.0U/g·min, respectively.

Example 3-6

Other steps are identical with embodiment 1, but the composition of fresh-keeping agent wherein is:

Embodiment 3: the deionized redistilled aqueous solution of 1.5wt% sodium alginate, 0.15wt% citric acid and 0.25wt% calcium chloride;

Embodiment 4: deionized redistilled aqueous solution of 1.5wt% konjac glucomannan, 0.15wt% citric acid and 0.25wt% calcium chloride;

Embodiment 5: the deionized redistilled aqueous solution of 1.5wt% chitosan, 0.15wt% ascorbic acid, 0.25wt% calcium chloride;

Example 6: 1.5 wt% konjac glucomannan and 0.25 wt% calcium chloride in deionized redistilled aqueous solution.

In Example 3-5, on the 15th day of storage, under the action of heat treatment and preservatives, the cassava tubers did not undergo browning or rot, and still maintained the original quality, with light yellow color, good taste and sweet potato smell. The relevant quality inspection results are as follows: weight loss rate is 2.0-2.5%, hardness is 0.75-0.85kg/cm2, L* value is 43-49, starch content is 28.5-32.0%, soluble solid content is 2.35-2.65%, total phenols are 8.5-9.8 mg/100g, SOD and POD are 8.5-9.3U/g·FW·h, 21.0-24.0U/g·min, respectively.

When Example 6 was stored for 15 days, the L* value was 41-43. Compared with Examples 3-5, the surface color of the cassava was slightly darker, and the other indicators were not much different.

Comparative example 1-2

Comparative example 1: replace the above-mentioned antistaling agent with sterile water, and other steps are the same as in Example 1.

Comparative example 2: the deionized redistilled aqueous solution of 1.5wt% chitosan was used to replace the above-mentioned preservative, and other steps were the same as in Example 1.

On the 9th day of storage, compared with Example 1, the weight loss rate of cassava in Comparative Example 1 increased significantly, the surface color became darker, and wilting and wrinkling occurred. On the 12th day of storage, the soluble solid content rose to the highest point, and the starch content dropped to 27.3%, the root tuber surface began to rot and deteriorate. On the 9th day of storage, compared with Example 1, Comparative Example 2 had little change in cassava weight loss rate, starch content, and soluble solids content, but the surface color of cassava tubers became darker, and local browning occurred.

The measurement of embodiment 7 relevant properties

The cassava after thermal treatment in embodiment 1 (preservative A), embodiment 2 (preservative B), embodiment 5 (preservative C) and comparative example 1 (CK) soaks 5min in corresponding preservative, naturally Dry it in the air, put it into a 0.01mm polyethylene bag and vacuum pack it, store it in an artificial climate box (RH is 85%-90%) at (25±0.5)°C, take a sample every 3 days during storage, and repeat 3 times for each treatment. Second-rate.

(1) Weight loss rate: measure the mass of cassava before storage, then measure it every 3 days, repeat the measurement 3 times each time, and calculate the weight loss rate with the following formula.

(2) Hardness: use a texture analyzer to measure, press down along the cross-section of cassava for TPA test, measure 2 points on each side, repeat 3 times, and take the average value.

(3) Color: measure with a spectrophotometer, measure 4 points on each side, and record the color change (L ^* value); among them, -L ^* means change to dark color direction, +L ^* means change to light color direction.

(4) Starch content is determined according to GB/T25219-2010.

(5) Soluble solids (TSS) content: measured with a refractometer.

(6) Total phenol content: determined by the Folin-Ciocaileu method.

(7) Peroxidase (POD) and superoxide dismutase (SOD) activities: measured by ultraviolet absorption method and nitrogen blue tetrazolium (NBT) photoreduction method, respectively.

At least 3 repetitions were set up for each indicator, and the experimental data were Said that Excel and SAS9.0 software were used for data processing and significance analysis of differences.

Embodiment 8 studies the impact of different preservatives combined heat treatment on cassava quality

(1) Effect on weight loss rate of cassava

The weight loss rate is one of the important indicators to evaluate the preservation effect. The water content of fresh cassava is as high as 65%. The weight change during storage is mainly due to the water loss caused by respiration, which leads to obvious wilting and wrinkling of the root tubers, which affects the appearance quality. The weight loss rate curves under the 4 different treatment methods of Example 7 are shown in Figure 2. During the storage period, the weight loss rates of all treatments first increased, and then gradually tended to balance. The cassava in the control group had begun to rot after being stored for 12 days, and the weight loss rates of the other treatment groups were significantly different from those in the control group (P<0.05). It can be seen from Figure 2 that the weight loss rate of the combination of 1.5wt% chitosan+0.15wt% ascorbic acid+0.25wt% calcium chloride (preservative C) is slightly lower than other treatments.

(2) Effect on cassava hardness

Root hardness reflects the maturity and senescence of fruits and vegetables, and is another important factor affecting the storage quality of cassava. During cassava storage, due to water loss and changes in nutrient components, its hardness is reduced, and the roots of cassava appear wilting and wrinkling. It can be seen from Figure 3 that under different treatments, the hardness of cassava tubers showed a downward trend during storage. On the 12th day, the firmness of fruits treated with preservatives A, B, and C was 0.2, 0.17, and 0.27kg/cm ² higher than that of the control group (CK), respectively, and the firmness of root tubers treated with preservative C was significantly better than that of other groups, and was always at the highest Level. It shows that the combination of chitosan, ascorbic acid and calcium chloride can more effectively inhibit the respiration and post-ripening softening of cassava tubers, so that it can maintain good fresh food quality.

(3) Effect on the color of cassava

It can be seen from Figure 4 that during the entire storage period, under different treatments, the color L ^* value of cassava pulp gradually decreased, indicating that with the prolongation of storage time, the brightness of cassava tubers will gradually decrease. On the 9th day of storage, the decreasing rates of L ^* values in the four groups were 16.4%, 18.6%, 10.1%, and 22.6%, respectively, and the decreasing rate was the smallest in group C, and the difference was extremely significant (P<0.01). At 12-15 days, the cassava tubers treated by the control group had begun to rot, and there was no significant difference between treatments B and C. The L ^* value of cassava tubers treated with preservatives was significantly higher than that of the control group during the whole storage period, indicating that the treatment of preservatives is beneficial to maintain the light yellow color of cassava pulp.

(4) The influence of cassava starch content

Starch content is one of the main nutritional indicators of cassava. It can be seen from Figure 5 that under different treatment methods, the starch content of cassava tubers during storage generally showed a gentle downward trend, and the longer the storage time, the lower the starch content. The starch content in the control group decreased the fastest, and the preservative C treatment decreased the slowest. On the 3rd to 9th day, the root starch content of preservative B was the highest. On the 9th to 15th day, the starch content of cassava root treated with preservative was significantly higher than that of the control group, and its cassava starch content was always maintained at a high level. The cassava tubers treated in the group had begun to rot, and the difference was extremely significant (P<0.01), indicating that the preservative treatment could maintain the starch content of cassava and prevent starch conversion.

(5) Effect on Cassava Soluble Solids (TSS) Content

The level of TSS content reflects the nutritional quality of fruits and vegetables to a certain extent. As shown in Figure 6, the TSS content of cassava tuber root is on the rise in the storage period overall, compares with contrast, the rate that the TSS rise of the preservative agent of the present invention handles group is relatively slow, and the TSS content of control group cassava reaches to 12d when the 12th day. 5.29% max, then starts to rot. Three kinds of preservatives (A, B, C) can significantly reduce the change of cassava soluble solids content. On the 15th day, the TSS content was 3.27%, 2.77%, 2.55%, respectively, and there was no rot. It shows that the preservative treatment is beneficial to maintain the quality of cassava, and can inhibit the transformation of cassava starch into soluble sugar.

Embodiment 9 studies the influence of different preservatives combined heat treatment on cassava SOD and POD enzyme activity

Superoxide dismutase (SOD) and peroxidase (POD) are important enzymes in plant protective enzyme system. SOD can remove reactive oxygen species produced in the metabolic process and play a key role in maintaining the balance of oxygen metabolism. It can be seen from Figure 7 that with the prolongation of storage time, the SOD enzyme activity of cassava tubers in each treatment showed a trend of first increasing and then decreasing. The peak of SOD activity in the control group appeared on the 6th day, and the peak value was 10.20 U/g·FW·h, then dropped sharply, and cassava roots rotted after 12 days. The peaks of SOD activity of preservatives A, B, and C all appeared on the 12th day, and the peaks were 10.22, 11.07, and 12.16 U/g·FW·h, respectively, which were 17.47%, 27.24%, and 36.32% higher than those of the sterile water control group , the difference among treatments was extremely significant (P<0.01).

POD is the key enzyme that causes the browning of fruits and vegetables. It can catalyze the oxidation of phenolic substances by peroxides, eventually leading to the browning of fruit and vegetable tissues and affecting the quality of fruits and vegetables. As shown in Figure 8, during the storage period, the POD activities of cassava tubers under the four treatments generally showed a trend of first increasing and then decreasing. The control group reached the highest value on the 12th day, and then the cassava began to rot. During the entire storage period, the cassava POD activity in the control group was significantly higher than that in the preservative treatment group, and the difference between treatments was significant (p<0.05). In the early storage period (0-6d), the inhibitory effect of preservative B on POD enzyme activity was better than that of preservative C, while in the late storage period (9-15d), the inhibitory effect of preservative C on POD enzyme activity was better than that of preservative B. From the above results, it can be seen that fresh-keeping treatment is beneficial to inhibit the high activity of SOD in cassava root and effectively maintain the lower POD activity, thereby delaying the quality deterioration and tissue aging process of cassava during storage.

Embodiment 10 studies the impact of different preservatives combined heat treatment on cassava total phenols

Phenolic substances are important secondary metabolites in plants, which have natural antioxidant activity and have certain effects on the quality, color, flavor and stress resistance of fruits and vegetables. The amount of its content directly affects the browning process of fruits and vegetables. Therefore, it is of great significance to study the change law of the content of phenolic substances in the storage period for regulating the quality of cassava roots. The changes in polyphenol content of cassava treated with different preservatives are shown in Figure 9. The results showed that during storage, the total phenol content of cassava root showed an upward trend in the early stage, and then began to decline, which was consistent with the research results of sweet potato, taro, and lotus root. On the 9th day of storage, the polyphenol content of each group reached the maximum value of 14.6, 13.2, 10.1, and 18.9 μg/gFW respectively. The three preservatives all effectively inhibited the increase of the total phenol content, and the antistaling agent C treatment had the better inhibitory effect .

The postharvest physiological deterioration of cassava is mainly physiological browning in the first stage and soft rot caused by microorganisms in the second stage. The present invention finds that the storage and fresh-keeping effect of cassava can be effectively improved by using a composite preservative combined with heat treatment. In the present invention, the fresh potato tubers are first heat-treated to slow down respiration and inhibit cell metabolism, then soak the cassava tubers with a composite preservative, and finally store them in vacuum packaging at room temperature to prevent the infiltration of O and the _oozing of moisture and _CO . Inhibit the browning of cassava and the growth and reproduction of microorganisms on the surface, so that the physiological and biochemical indicators of fresh potato roots are significantly improved compared with the control group, and effectively reduce the water loss rate and nutrient consumption of fresh potatoes, and maintain the hardness and Crispness, delaying starch degradation, and significantly controlling the increase in soluble solids content. It maintains a high level of SOD enzyme activity, delays the increase of POD enzyme activity, reduces the total phenol content, effectively prolongs the storage period of cassava roots after harvest, and inhibits the deterioration of its quality. Preservation provides the best solution.

The present invention studies the effects of different preservatives combined with heat treatment on the quality and storage period of cassava tubers during normal temperature storage, and monitors the dynamic change process of fresh potato physiology and quality during storage, and seeks a new suitable method. The storage and preservation method of fresh cassava provides a theoretical basis and a new method for postharvest storage and preservation of cassava.

Claims (10)

1. a cassava color-protecting and antistaling agent, is characterized in that, the composition of described antistaling agent comprises deionization weightSteam two or three in water and following three kinds of components:

(A) one or both in shitosan, sodium alginate and konjaku glucomannan or three kinds;

(B) one or both in citric acid and ascorbic acid;

(C) calcium chloride.

Preferably, in described antistaling agent, do not contain anticorrisive agent.

2. cassava color-protecting and antistaling agent according to claim 1, is characterized in that, the group of described antistaling agentBecome two or three in deionization redistilled water and following three kinds of components:

(A) one or both in shitosan, sodium alginate and konjaku glucomannan or three kinds;

(B) one or both in citric acid and ascorbic acid;

(C) calcium chloride.

3. cassava color-protecting and antistaling agent according to claim 1 and 2, is characterized in that, described (A),(B) and (C) mass percent of two or three of component summation is 1～10wt%, preferably 1～6wt%.

Preferably, the mass percent of described (A) component is 1～3wt%, preferably 1.5～2wt%. Described(B) mass percent of component is 0.1～2wt%, preferably 0.15～0.5wt%. The matter of described (C) componentAmount percentage is 0.1～0.5wt%, preferably 0.2～0.4wt%.

4. according to the cassava color-protecting and antistaling agent described in claim 1-3 any one, it is characterized in that described woodThe component of potato color-protecting and antistaling agent and mass percent are:

(A) one or both in shitosan, sodium alginate and konjaku glucomannan or three kinds, 1～3wt%,Preferably 1.5～2wt%;

(B) one or both in citric acid and ascorbic acid, 0.1～2wt%, preferably 0.15～0.5wt%;

(C) calcium chloride, 0.1～0.5wt%, preferably 0.2～0.4wt%;

Surplus, deionization redistilled water.

5. a processing method for keeping fresh for cassava, described method comprises heat treatment step, claim 1-4The cassava color-protecting and antistaling agent treatment step of any one and vacuum packaging step.

6. method according to claim 5, is characterized in that, described method comprises following technological process:Raw material selects → cleans → and the cassava of remove the peel → shaping, cutting → heat treatment → claim 1-4 any one protectsLook antistaling agent processing → air-dry → pack → vacuum packaging → storage.

Preferably, described raw material is selected step and is specially: select have no mechanical damage, without disease and pest, quality betterNew fresh cassava as raw material.

Preferably, described cleaning, peeling and shaping, cutting step are specially: by raw material remove silt,After cleaning, remove the peel with flowing water, be cut into edibility required form.

Preferably, described heat treatment step is specially: by cassava put into 45-80 DEG C hot water blanching 2～10min, removes surface moisture after taking out.

Preferably, described antistaling agent processing, air-dry step are specially: cassava is after heat treatment placed inIn described cassava color-protecting and antistaling agent, soak 5～10min, air-dry after taking out.

Preferably, described pack, vacuum packaging and storage step are specially: cassava is placed in to packaging bag,Vacuum packaging, is placed in 15-30 DEG C, preferably under 25-28 DEG C of condition, preserves.

7. method according to claim 6, is characterized in that, fitting in described shaping, cutting stepClose edible required piece, bar or the sheet of being shaped as; Wherein, the length of piece is 2～5cm, and thickness is 2～5cm;The length of bar is 8～10cm, and thickness is 2～3cm; The thickness of sheet is 2～4cm.

8. method according to claim 6, is characterized in that, the temperature in described heat treatment step is excellentElect 55～70 DEG C as, the time is preferably 4～6min.

Preferably, in described heat treatment step, must remove the moisture on cassava surface completely.

9. method according to claim 6, is characterized in that, in antistaling agent processing, air-dry stepSoak time is preferably 3～10min, and the volume ratio of cassava and described antistaling agent is 1:2～5 (preferably 1:3).

10. method according to claim 6, is characterized in that, the bag material in packaging step isPolyethylene (PE), polypropylene (PP) or aluminium foil (PT).

Preferably, the vacuum in described packaging step is-0.06MPa～-0.1MPa.