Method for degrading nitrites in foods

A nitrite and food technology, applied in the direction of bacteria used in food preparation, food processing, food processing, etc., can solve the problems of insignificant nitrite content and achieve good results

Inactive Publication Date: 2017-12-12
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when the pH is lower than 5.0, the NiR enzyme activity is low and cannot significantly degrade the nitrite content in the system

Method used

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  • Method for degrading nitrites in foods
  • Method for degrading nitrites in foods
  • Method for degrading nitrites in foods

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] Example 1 Screening process of synergistic degradation of sodium nitrite by nitrite reductase (recombinant NiR) and malic acid.

[0042] (1) Extract crude enzyme liquid from recombinant Escherichia coli BL21

[0043] ① Bacterial culture: Inoculate the recombinant Escherichia coli BL21 strain (containing the nitrite reductase gene of Lactobacillus casei LCR6013) preserved in the laboratory into the LB liquid medium containing 50 μg / mL ampicillin, at 37°C and 180rpm Cultivate under shaking for 8 hours to obtain seed liquid; inoculate the seed liquid into LB liquid medium containing 50 μg / mL ampicillin at 2% inoculum amount, and culture with shaking at 37° C. and 180 rpm. OD was detected every 30 minutes during shaking culture 600 , when OD 600 When ≈0.6 (logarithmic growth phase), IPTG with a final concentration of 1 mmol / L was added to induce expression, and cultured with shaking at 30° C. and 180 rpm for 4 hours to obtain a culture solution.

[0044] ②Extraction of c...

Embodiment 2

[0072] Example 2 Screening process of synergistic degradation of sodium nitrite by nitrite reductase (natural NiR) and vitamin C.

[0073] (1) Extract crude enzyme liquid from Lactobacillus casei LCR6013

[0074] The activated seed solution was inoculated with 2% volume fraction to contain 100 μg / mL NaNO 2 In the LB liquid medium, cultured on a shaker at 30°C and 180r / min for 24h, centrifuged the medium for 10min (8000r / min, 4°C), discarded the supernatant, washed with sterile water and centrifuged for 10min ( 8000r / min, 4°C), washing and centrifugation were repeated twice to obtain NiR-containing cells and weighed, and the collected cells were suspended in 50mM HEPES buffer (pH 7.4, 5mmol / LDTT, 0.2% trypsin inhibitor) to become The bacterial suspension with a final concentration of 200g / L (wet bacterial weight / buffer solution) was subjected to sonication (35%, 10min, 2s off for 2s) in an ice-bath environment, and after centrifugation for 20min (8000r / min, 4°C), The supernat...

Embodiment 3

[0076] Example 3 Screening process of synergistic degradation of sodium nitrite by nitrite reductase (recombinant NiR) and citric acid.

[0077] (1) Crude enzyme solution extracted from recombinant Escherichia coli BL21

[0078] ① Bacterial culture: inoculate the recombinant Escherichia coli BL21 (containing the nitrite reductase gene of Bacillus cereus LJ01) preserved in the laboratory into LB liquid medium containing 100 μg / mL ampicillin, and inoculate at 37°C and Shake culture at 180 rpm for 12 hours to obtain seed liquid; inoculate the seed liquid into LB liquid medium containing 100 μg / mL ampicillin at 1.5% inoculum amount, and shake culture at 37°C and 180 rpm. OD was detected every 30 minutes during shaking culture 600 , when OD 600 When ≈0.7 (logarithmic growth phase), the expression was induced by adding IPTG at a final concentration of 0.5 mmol / L, and cultured with shaking at 16°C and 180 rpm for 20 hours to obtain a culture solution.

[0079] ②Extraction of crude...

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Abstract

The invention discloses a method for degrading nitrites in foods. The method comprises the following steps of adding nitrite reductase in food sauce, performing standing for reaction for 6-12h at the temperature of 27-37 DEG C, then regulating a pH value with an organic acid to 2.0-5.5, and performing standing for reaction for 4-12h at the temperature of 20-37 DEG C, wherein a nitrite reductase gene is from edible bacteria. According to the method provided by the invention, by adopting a method for degrading sodium nitrite by adopting a crude enzyme solution firstly and then adopting the organic acid, and compared with a mode of singly using the organic acid or the nitrite reductase, the method has a good effect; the degradation rate of the sodium nitrite is calculated by determining the concentration of the nitrite in the system with a naphthylethylenediamine hydrochloride method to reach 90 percent or above; and the method can be used for degrading high-nitrite foods with a pH value larger than 5.0, such as pickles.

Description

technical field [0001] The invention belongs to the technical field of degrading nitrite, and in particular relates to a method for synergistically degrading nitrite in food with nitrite reductase and organic acid. Background technique [0002] Nitrite widely exists in the field of food preservation, especially smoked and pickled products. Pickled food (sauerkraut, bacon, dried fish, etc.) has special flavor and texture, and is deeply loved by people. Nitrates and nitrites have antiseptic effects, and also have the function of color development in meat processing, so they are widely used in smoked and pickled foods. However, nitrate will generate nitrite under the action of nitrate reductase, resulting in excessive nitrite residue in smoked and pickled food, and nitrite will cause great harm to the human body. [0003] Nitrite is a potential carcinogen, widely present in various foods and organic acids can effectively degrade nitrite. Common organic acids mainly include m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A23L5/20
CPCA23L5/25A23L5/27A23L5/28A23V2002/00A23V2400/125A23V2400/175A23V2400/169A23V2250/044A23V2250/032A23V2250/022A23V2250/02A23V2250/042A23V2300/50
Inventor 刘冬梅陈思敏杨丹霞
Owner SOUTH CHINA UNIV OF TECH
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