Test Results

Results of Korea Food Research Institute Conducted by the Ministry of Agriculture

Summary

1. When electrolyzed water is used to rinse the food, its total amount of vitamins is 1/2 to 1/3 times higher than when chemicals are used.

2. Only about 1/58 to 1/70 residual chlorine of a chlorine solution was detected in electrolyzed water.

3. From food preparation to serving , the number of E. Coli bacteria found in the salad satisfied the safety level when the salad was rinsed with electrolyzed water, but, the result was quite the opposite when a chlorine solution was used.

4. Based on the result of microbial counts, the number of E. Coli bacteria failed to meet the safety standards when utensils and containers were washed with a chlorine solution, posing a threat of cross-contamination. However, cleaning the tools with electrolyzed water completely satisfied the safety standards after a single rinse cycle.

5. When other harmful factors are controlled, the result clearly shows that after five minutes of being soaked in electrolyzed water, utensils and rubber gloves, used for preparing the salad, had no signs of bacteria. This means that, electrolyzed water effectively prevents cross-contamination by eliminating bacteria at an early stage while satisfying the safety standard.

6. Active chlorine, which is the main component of electrolyzed water, leaves almost no chlorine residue. Accordingly, water and meal preparation time can be saved dramatically by cutting the rinsing cycle to one. Chlorine solutions, however, requires more than four rinsing cycles because of high chlorine residue. 7. If raw foods are consumed (i.e. fruits and vegetables) at school cafeterias and are contaminated during the preparation, this may cause significant food safety problems. Electrolyzed water proves to be an effective answer to this problem by improving and controlling key safety measures, which chlorine disinfectants were unable to address. Based on “Technological Development for Microbiological Quality Control and Establishment of the HACCP System on Fruit-Vegetables Salads for School Food Service System (2005. 07)” by the KFRI (Korea Food Research Institute) at the MIFAFF (Ministry for Food, Agriculture, Forestry and Fisheries)

1. A traditional vegetable salad preparation time and temperatures

Kitchen temperature
before preparation
Internal temperature
of the salad
Average time taken from the storage room to the final stage of the preparation
(The first serving of the salad)
Chlorine15 ~ 20℃6.25 ~ 12.25℃269 minutes
Sodium hypochlorite
(electrolyzed) water
17 ~ 23℃10.5 ~ 16.2℃256 minutes

Results

When compared with the regular production process, the most significant difference is that the rinsing process was reduced to 1/3 during the pre-processing stage to save 13 minutes in cooking time although the kitchen temperature and internal temperature of the salad are high. (A storage temperature of ingredient for fresh vegetables is around 10º)

2. Physico-chemical changes during preparation of the vegetable salad

A. Chlorine residue level

Soaked in a chlorine solution (active chlorine of 100 ppm) for 5 minutesSoaked in sodium hypochlorite water (active chlorine of 165 ppm) for 5 minutes
ItemLettuceSaladCherry tomatoLettuceSaladCherry tomato
PPM1.75PPM1.16PPM1.42PPM0.03PPM0.02PPM0.02PPM
After 4 rinse cycles (tap water)After single rinse cycles (tap water)
0.01 ~ 0.02PPM0.01 ~ 0.02PPM

Results

The results indicate that during the preparation of a traditional salad, only about 1/58 to 1/70 residual chlorine of a chlorine solution was detected in electrolyzed water. (Amount of residual chlorine: Electrolyzed water is similar to tap water, but chlorine solution is up to 300 times higher than it)
Conventional chlorine solutions require multiple rinse cycles, due to high chlorine residue. Active chlorine in sodium hypochlorite can be easily decomposed with natural sun lay, creating many benefits: Low chlorine residue level, safe to the environment and the human body, saving preparation time, labor, and the amount of rinse water.

Changes in color values and firmness of lettuce with different treatments during storage at 10º

ComponentChanges in color differenceFirmness
EW-1Initial116.67 ± 1.55 g/cm2
7th days of storage44.33 ± 0.51 g/cm2
EW-2Initial87.33 ± 1.41 g/cm2
7th days of storage21.00 ± 1.73 g/cm2EW-1 Immersed in Electrolyzed water produced
from diaphragm type 1 generator
EW-2 Immersed in Electrolyzed water produced
from diaphragm type 2 generator
EW-3 Immersed in Electrolyzed water produced
from non-diaphragm type generator
EW-3Initial124.00 ± 1.67 g/cm2
7th days of storage71.67 ± 1.04g/cm2

Results

Changes in color difference right after treatment were minimal across the samples except treatment EW-2, however, after 2 days treatment EW-3 showed a comparatively low value.
And the firmness measured by Rheometer, all samples maintained the firmness right after treatment with an exception of treatment EW-2, which showed reduction ratio of 29.84% in firmness. But after 7 days only the treatment EW-3 maintained generally constant value.

3. Bacterial counts on each step of the salad preparation

A. When a conventional chlorine solution is used

LettuceCeleryCherry tomatoNote
Right after the procurement inspectionTotal bacterial number(CFu/g)1.38X1051.98X1061.47X105Bacterial safety standards for ingredients
- Total bacterial number : below 106 (CFu/g)
- E.Coli number : below 103 (CFu/g)
E.coli number(CFu/g)7.10X1034.20X1028.15X104
After being stored for 93 min.Total bacterial number(CFu/g)1.43 X 105 ~ 2.05 X 106 (CFu/g)Slight increase in numbers
E.coli number(CFu/g)2.60 X 102 ~ 7.80 X 104 (CFu/g)
After rinsed with chlorine solutionTotal bacterial number(CFu/g)1.75 X 103 ~ 2.61 X 104 (CFu/g)The bacterial number drop to 1/10 to 1/80 of the initial stage after the rinsing, and is below the safety standard. (excluding E. Coli on Cherry tomatoes) The bacterial numbers barely changed after 4 rinse cycles
E.coli number(CFu/g)4.90 X 10 ~ 1.58 X 103 (CFu/g)
After cookingTotal bacterial number(CFu/g)1.51 X 105 (CFu/g)Failed to meet the safety standards for the salad: Total bacterial number should be 105, E. Coli number 102
E.coli number(CFu/g)2.05 X 102 (CFu/g)
After 48 hr (store) & 24 min. (serving)Total bacterial number(CFu/g)About 5 fold increaseThe numbers are even bigger than the previous stage and are similar to the numbers from the first stage
E.coli number(CFu/g)About 2 fold increase

Results

The results indicate that during the preparation of a traditional salad, only about 1/58 to 1/70 residual chlorine of a chlorine solution was detected in electrolyzed water. (Amount of residual chlorine: Electrolyzed water is similar to tap water, but chlorine solution is up to 300 times higher than it)
Conventional chlorine solutions require multiple rinse cycles, due to high chlorine residue. Active chlorine in sodium hypochlorite can be easily decomposed with natural sun lay, creating many benefits: Low chlorine residue level, safe to the environment and the human body, saving preparation time, labor, and the amount of rinse water.

B. When sodium hypochlorite water

LettuceCeleryCherry tomatoNote
Right after the procurement inspectionTotal bacterial number(CFu/g)6.40X1051.25X1062.42X105Mostly fail to meet the safety standards
- Total bacterial number : 106 (CFu/g)below
- E.Coli number : 103 (CFu/g) below
E.coli number(CFu/g)3.85X1036.10X1021.02X104
After being stored for 106 min.Total bacterial number(CFu/g)2.80 X 105 ~ 1.30 X 106 (CFu/g)Slight increase in numbers but no drastic change
E.coli number(CFu/g)6.50 X 102 ~ 1.37 X 104 (CFu/g)
After rinsed with chlorine solutionTotal bacterial number(CFu/g)3.45 X 10 ~ 5.60 X 102 (CFu/g)The bacterial number drop to 1/380 to 1/10,000 of the initial stage after the rinsing, and is below the safety standard. After a single rinse cycle, the bacterial numbers remained changed
E.coli number(CFu/g)Undetected3.60 X 10(CFu/g)
After cookingTotal bacterial number(CFu/g)3.35 X 102 (CFu/g)Satisfying the safety standard for the salad
E.coli number(CFu/g)2.50 X 10 (CFu/g)
After 47 hr (store) & 28 min. (serving)Total bacterial number(CFu/g)About 3 fold increaseThe number increased from the previous stage but still satisfies all the safety standards. Total bacterial numbers and E. Coli numbers are 1/700 and 1/13 of the numbers from the results of the chlorine solution respectively.
E.coli number(CFu/g)About 1.3 fold increase

Results

Electrolyzed water has been proved to be an effective, sanitary measure to control problems, emerged in the case of the chlorine solution and satisfies the safety standard throughout all stages, despite the fact that an average kitchen temperature was 2º higher, the initial bacterial numbers on the main ingredient exceeded the safety standards.

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