IJERD – International Journal of Environmental and Rural Development (2023) 14-1

Research article
erd

Research article
Improvements in Preservation Properties of HomemadeStyle Pickled Cucumber in Cambodia

SOKLY SORM
Graduate School of Agriculture, Tokyo University of Agriculture, Tokyo, JapanSHUKI MURAMATSU*
Showa Women’s University, Tokyo, Japan
Email: s-muramatsu@swu.ac.jp

MASATAKA UCHINO*Tokyo University of Agriculture, Tokyo, Japan
Email: muchino@nodai.ac.jp

YOSHIKI MURAMATSU
Tokyo University of Agriculture, Tokyo, JapanDAIKI OKATokyo University of Agriculture, Tokyo, Japan

NARONG TOUCHTokyo University of Agriculture, Tokyo, JapanYURI TANIOKA
Tokyo University of Agriculture, Tokyo, Japan

TAKAHIKO NAKAMURATokyo University of Agriculture, Tokyo, JapanTORU NAKAJIMATokyo University of Agriculture, Tokyo, Japan

MOTOE SEKIDO
Yamanashi Gakuin Junior College, Yamanashi, JapanSHOTARO KAWAKAMITokyo University of Agriculture, Tokyo, JapanCHIM CHAY
Royal University of Agriculture, Phnom Penh, Cambodia

MARI ARIMITSU
Institute of Environmental Rehabilitation and Conservation, Tokyo, Japan

MACHITO MIHARATokyo University of Agriculture, Tokyo, Japan
Received 16 December 2022

Accepted 10 May 2023(*Corresponding Author)

Abstract Pickled cucumbers selling at wet markets in Cambodia are popular among local
people. It has been reported that pickles using homemade recipes are at a high risk of spoilingand causing food poisoning, as there are no heating steps in the production process. Therefore,
it is necessary to improve the hygienic conditions of the food supply to make safe pickles in
Cambodia. Heat treatments using hot pack filling and pasteurization lead to microbiologicallyⒸ ISERD

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safe products and extended shelf life. This study aimed to examine the effect of heat treatments(hot pack filling and pasteurization) on preservative properties and to evaluate the acceptabilityof the pickled cucumbers prepared with the heating process. Pickled cucumbers prepared withand without the heating process were made using a traditional Cambodian recipe and stored at
30 °C for 7 days. The presence of total viable bacteria, coliforms, Escherichia coli, yeasts, andmolds in the pickled products was tested during the storage periods. The samples without theheating process resulted in contamination with coliforms, E. coli, yeasts, and molds and werein an initial putrefactive state because of the number of total viable bacteria. On the other hand,coliforms, E. coli, yeasts, and molds were not detected in the samples prepared with the heatingprocess from Day 0 to Day 7. This result indicated that the pasteurization treatment killed
many spoilage microbes, including foodborne pathogens. To investigate the acceptability ofthe pickled cucumbers prepared with the heating process, sensory evaluation tests were
performed. From the results of the sensory evaluation and questionnaire survey, there was thepossibility of acceptance of the pickled cucumbers prepared with the heating process madeeither in Japan or Cambodia by the Cambodian panelists; however, further improvement in thesoftness of the pickles was commented upon.
Keywords cucumber, homemade-style pickle, pasteurization, sensory evaluation,
acceptability

INTRODUCTION
Pickled cucumbers are popular pickles in Cambodia. Nearly all Cambodian people like to eat pickles
in their daily diet. These pickles are mostly produced at home using traditional recipes and are usuallysold at wet markets in Cambodia. The Ministry of Health in Cambodia reported that after eating thesehomemade-style pickled cucumbers, many people suffer from symptoms of food poisoning,
including diarrhea, abdominal pain, fever, and nausea (MoH, 2016). A review report has describedthat important foodborne pathogens have been detected in the food supply in Cambodia (Thompson
et al., 2021). Studies by Muramatsu et al. (2020a, 2020b) and Chrun et al. (2017) showed that somemicroorganisms could cause food spoilage and food poisoning in homemade pickled products soldat wet markets. The current preparation method for homemade-style pickles is generally as follows.
Fresh vegetables are washed with tap water. Then, they are submerged in boiled water or normaltemperature water along with seasonings. The pickles are then soaked for two to four days at room
temperature. The room temperature ranges from 25 to 35 °C according to the tropical climate of
Cambodia. Homemade pickles are commonly stored at room temperature at approximately 30 °C
during and after the production of pickles. Muramatsu et al. (2022) prepared three kinds ofhomemade-style pickles using traditional Cambodian recipes and evaluated the microbial quality of
those pickles. The report revealed that microbial growth was observed in all pickles starting at Day
0, which poses a high risk of food spoilage and food poisoning. Therefore, we focused on the
production process for obtaining microbiologically safe products. Therefore, this study aimed to
examine the effect of thermal preservation methods on the microbial quality of pickled cucumbers.
The heating step is considered to affect the taste of the pickled cucumber, and therefore we also
investigated the acceptability by Cambodian people.
Pickled cucumbers were prepared with and without the heating process following theCambodian homemade-style recipes. For the purpose of providing safe pickle products in Cambodia,
we aimed to investigate the effect of the heating process (hot pack filling and pasteurization) on the
microbial quality of cucumber pickles. The acceptability of these pickled cucumbers was examinedbased on sensory evaluation in Cambodia.
OBJECTIVE
The objectives of this study were 1) to examine the effect of the heating process (hot pack filling andpasteurization) on the preservative properties of the pickled cucumbers and 2) to evaluate theacceptability among Cambodian people of the pickled cucumbers prepared using the heating process.
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METHODOLOGY
Materials, Production Process, and Procedure for Samples Testing
The pickled cucumbers were prepared with and without a heating process according to traditional
Cambodian recipes (Muramatsu et al., 2022) as samples for the test. All ingredients and seasonings
were purchased at a supermarket in Tokyo, Japan. The seasoning mixture was prepared using 30.6
grams of salt and 700 ml of water. The ingredients used to make the samples were 200 g (5 pieces)of cut fresh cucumbers, 4.5 g (1 piece) of garlic, and 1.0 g (2 pieces) of chili. All ingredients weremixed with the seasonings. Figure 1 shows the production process of pickled cucumbers with theheating process. Cucumbers were washed with tap water and wiped with a paper towel. Cucumberswith diameters of 2.2-3.2 cm were cut into lengths of 7 cm using a knife. The garlic was peeled andsliced. A piece of chili was sliced into rings. The liquid seasoning was heated to boiling. The heatedliquid seasoning, 120 ml, a piece of cucumber, and a few slices of garlic and chili were placed into a
glass bottle up to 3-5 mm from the bottle lid. After closing the lid of the bottle (sealing), the bottle
was turned upside down. The hot glass bottle filled with seasoning and cucumber was submerged in
hot water at a temperature of 80 °C. Then, the hot water was heated to boiling in a pot. After coming
to a boil, the glass bottle was maintained in boiling water for 10 minutes to raise the center
temperature of the cucumber to above 75 °C. After this pasteurization, the glass bottle was cooled atroom temperature in an inverted state for a few hours.
Fresh Cucumber

Glass bottle

Boiling liquid seasoning

Sealing(hot pack filling)

Pasteurization(boiling 10 min, center
temperature >75 C)

Pickled cucumber

Slice garlic and chili

Fig. 1 Production process of pickled cucumber prepared with the heating process
The pickled cucumbers without a heating process were prepared using the same seasoning andingredients as the heated sample shown in Fig. 1. After placing the ingredients into the glass bottle,
the liquid seasoning at room temperature was added. The lid of the glass bottle was closed.
Preparation of the Samples with the Heating Process for Examination of Preservability
To examine the preservability of cucumber pickles, the samples were observed for 7 days, as thevendors who sold pickles at wet markets reported that the shelf life of their products wasapproximately 2-4 days according to our survey and that the products were kept for 3-4 days during
preparation by the traditional recipe.
The food properties of the samples during the storage periods, the Brix values, salt
concentrations, and pH of the pickle liquid seasoning, were measured by using a Brix refractometer(Atago, Tokyo, Japan), a salt meter (Horiba, Kyoto, Japan), and a pH meter (Horiba), respectively.
To investigate the safety of the samples, microbiological tests were conducted by detecting total
viable bacteria, coliforms, E. coli, yeasts, and molds. In total, 10 g of solid and liquid pickled
cucumber was mixed with 90 ml of phosphate-buffered saline (PBS) (ELMEX, Tokyo, Japan) andplaced in a sterilized storage bag. To mix well, samples were crushed using a hammer. After mixing,
1 ml of the sample suspension was mixed with 9 ml of PBS. A series of diluted samples were used
for the detection of total viable bacteria, coliforms, E. coli, yeasts, and molds in the samples.
Commercial sheet-shaped, dry, and ready-made microorganism detection media with nonwoven
fabric, MC-media PadTM (JNC Corporation, Tokyo, Japan), were used for the detection of
microorganisms. One milliliter of sample solution at each dilution was spread onto each specific MCⒸ ISERD

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media PadTM. After spreading, the MC-Media PadTM "Aerobic Count (AC)", MC-Media PadTM "EC",and MC-Media PadTM "YM" were incubated at the set temperature of 35 °C for 48 hours, 24 hours,and 25 °C for 72 hours, respectively for assessment of total viable bacteria, coliforms, E. coli, yeasts,
and molds. After incubation, the log10 CFU/g was calculated using media on which there were 30300 colonies available to count. Three repetitions were carried out for the detection.
Sensory Evaluation of the Pickled Cucumber Made in Japan and Cambodia
For sensory evaluation, we prepared pickled cucumber samples with two pasteurization times, 10
and 20 minutes, similar to the samples prepared for the examination of preservability, as shown in
Fig. 1. It was assumed that a longer pasteurization provided a higher killing effect on the microbes
but that the texture might be unfavorably affected. Therefore, two kinds of pickled samples were
evaluated. The pickled cucumbers pasteurized for 10 minutes raised the center temperature to above
75 °C, and those pasteurized for 20 minutes raised the center temperature to above 80 °C.
We aimed to show that the pickles made in Japan following Japanese sanitation guidelines werealso able to produce in Cambodia, especially by using household cooking utensils. Besides, varietiesof cucumber for pickles are assumed to be different between Cambodia and Japan. And the difference
may affect the texture of the pickles, especially with heating samples. It was also important that how
acceptable for Cambodian people both pickles made in Cambodia and Japan. Therefore, we prepared
pickles made in Cambodia and Japan using local products for sensory evaluation.
The samples made in Japan were prepared using ingredients and seasonings purchased in Japan.
The samples made in Cambodia were prepared using ingredients and seasonings purchased in
Cambodia. All sensory was conducted in Cambodia. The panelists evaluated 2 samples with heatingfor 10 and 20 minutes. Twenty panelists evaluated the samples made in Japan at the Royal Universityof Agriculture (RUA) in Phnom Penh, and another 20 panelists evaluated the samples made in
Cambodia at a wet market in Prey Nop district in Preah Sihanouk. The purpose of sensory evaluationin this study is not a comparison pickles made in Cambodia and Japan. We aimed to investigate theacceptability of respective pickles. Therefore, no particular problem occurs when the panels weredifferent between the products in Cambodia and Japan.
The age of the evaluating panelists was 21-28 years (average: 23 years) at RUA and 22-60 years(average: 31 years) at the wet market. The color, sweetness, sourness, saltiness, flavor, texture, andoverall evaluation of each sample were quantified using a five-point hedonic scale (1: strongly dislike,
2: dislike, 3: neutral, 4: like, and 5: strongly like) for the sensory test (preference type).
RESULTS AND DISCUSSION
Examination of the Preservability of the Pickles Prepared with the Heating Process
To investigate the effects of the heating process on the quality of the samples, the nutritional
properties, and microbial quality were examined. During the storage period of 7 days, the Brix value,salt concentration, and pH values were measured (Table 1). The average Brix values of the pickled
cucumbers prepared with and without the heating process were 4.9 and 4.2, respectively. There is asignificant difference in the value of Brix. But the difference in Brix values between pickles withheating and without heating is assumed not to affect the preservation stability of the samples. The
average salt concentrations in the pickles prepared with and without heating were 4.9 and 4.3,
respectively. The Brix value and salt concentration were generally constant throughout the storage
period.
On the other hand, the pH value of the sample prepared with heating was 5.3 on Day 0 and 5.3
on Day 7, and that of the sample without heating was 5.5 on Day 0 and 4.3 on Day 7 (data not shown).
While the pH values of the heated samples were stable, those of the nonheated samples decreased
over time. This indicated that the pickled cucumber prepared without the heating process contained
microorganisms producing acids in the samples.

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Table 1 Nutritional properties of the pickles prepared with and without heating
Measured item

Brix (%)

Salt (%)

pH

Pickles with heating

4.9 ± 0.25 *4.9 ± 0.20

5.3 ± 0.18

Pickles without heating

4.2 ± 0.10 *4.3 ± 0.41

4.6 ± 0.35

(Mean ± standard deviation), the symbol (*) means a significant difference (p < 0.05).

Next, we examined the microbial quality of the pickled cucumbers by measuring the number of
total viable bacteria, coliforms, E. coli, yeasts, and molds. The total viable bacteria on Day 0 weremore than 5.00 log10 and over 7.00 log10 after Day 3. Coliforms were detected in samples from Day
0 to Day 7, and there were samples positive for E. coli. Yeasts and molds were detected in somesamples. A similar result was reported by Muramatsu et al. (2022). From the result of the experiment
for measuring the microbial quality of the pickles without heating, the pickles contained unacceptable
numbers of total viable bacteria on Day 3 for eating. Besides, coliforms, E. coli, yeast, and moldwere detected. Yeast and mold can cause putrefaction. Contamination of E. coli implies a risk of thepresence of other enteric pathogens. Enterohemorrhagic E. coli is classified as a severe hazard, which
is life-threatening for the general population, based on International Commission on MicrobiologicalSpecifications for Foods (Matthews et al., 2017). Taking this into consideration, the pickled
cucumbers without a heating process in this study were not safe for consumption.
On the other hand, coliforms, E. coli, yeasts, and molds were not detected in any of the samples
subjected to the heating process. In addition, total viable bacteria were almost not detected throughout
the storage time. The heating time for pasteurization was decided based on the effect of heating on
the texture of the cucumber. Due to this, the bactericidal effect of the heated samples seemed tochange depending on this condition. However, the number of CFU/g among the samples in whichsome total viable bacteria were detected was at most 5.00 log10. These results indicate that the heat
treatment was effective in killing microbes, but this heating step was barely effective for somemicroorganisms. For food preservation, a sufficient amount of salt and/or a lower pH value is
supposed to be used. Since the samples with the heat treatments, namely, the hot pack filling and 10
minutes of pasteurization, maintain their qualities sufficiently until Day 7, the process of adding heat
treatments may be a suitable procedure to make safe products that do not change the traditional taste.
Sensory Evaluation of the Samples Made in Japan and Cambodia
To investigate the acceptability characteristics of pickled cucumbers during the heating process,sensory evaluation tests were performed. Fig. 2 shows the results of the sensory evaluation tests ofsamples (a) made in Japan and (b) made in Cambodia. The average values of each sensory item forthe pickled cucumbers pasteurized for 10 min and 20 min made in Japan ranged from 2.8-3.6 and2.4-3.8, respectively (Fig. 2a). In the overall evaluation, both the 10- and 20-minutes pasteurization
samples scored approximately 3.0. There was no significant difference in accordance with the paired
t-test (5% significance level) between all characteristics, except for texture. The average value of
texture for the samples with 10 min of pasteurization was higher than that of the sample with 20 minof pasteurization, which was 3.4 and 2.4. This result showed that longer pasteurization affected the
texture of the cucumber. However, the overall evaluation scores were both approximately 3.0. Thisis a representative evaluation of whether or not the sample was considered acceptable. The results
indicated that the samples made in Japan were considered acceptable in the Cambodian market.
Figure 2b shows the results of the evaluation of pickled cucumbers with the heating process made in
Cambodia. The average scores of all evaluated items ranged from 2.6-3.6 and 2.3-4.0, respectively.
Except for color and texture, there were no significant differences between the evaluated items
according to a paired t-test (5% significance level).
Because the average score for color was close to 4.0, Cambodian panelists preferred the colorof the sample with pasteurization for 20 min made in Cambodia. The texture of the sample withpasteurization 20 min was given a lower rating score of 2.3. The heating treatment presumably causedⒸ ISERD

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a change in the texture of the cucumbers. Although the average values of sourness and flavor forboth samples did not exceed 3.0, the overall evaluation score given by the panelists was nearly 3.0.
Based on the results, the samples pasteurized for 10 min and 20 min made in Cambodia may also be
acceptable in the Cambodian market. In addition, the t-test for each characteristic used the averagescore between the samples made in Japan and Cambodia with 10 and 20 minutes of pasteurization.
There were no significant differences. Since a similar evaluation was obtained, there did not seem tobe differences in quality.
a

Color
5
4
3
2
1

Overall
Evaluation

Texture*Overall
Evaluation

Sweetness

Texture*Sourness

FlavorColor*
5
4
3
2
1

b

Sourness

Flavor

Saltiness

Pasteurization 10 min
Pasteurization 20 min

Sweetness

Saltiness

Pasteurization 10 min
Pasteurization 20 min

The symbol (*) means a significant difference (p < 0.05).

Fig. 2 Sensory evaluation of pickled cucumbers with pasteurization for 10 min and 20 min:(a) samples made in Japan and (b) samples made in Cambodia
Most Cambodian panelists commented that there was a lack of sourness for these pickled
cucumbers. Some panelists commented that sweetness and saltiness were lacking. If thesecharacteristics were to be improved, the overall evaluation would receive a higher rating. The heating
treatments, hot pack filling, and pasteurization were effective in killing microorganisms and wererecommended for pickle production. Although a longer heating process affected the texture (softness)of the pickled cucumbers, they received a nearly normal score on the overall evaluation from theCambodian panelists. From the results of the sensory evaluation and questionnaire survey, there was
the possibility of acceptance of the pickled cucumbers prepared with pasteurization made either inJapan or Cambodia by the Cambodian panelists; however, further improvement in the softness of the
pickles was commented upon. Regarding improvements for the product, some food additives arerecommended as they do not affect the softness of pickles and are effective in keeping
microbiological safety.
CONCLUSION
To investigate the effect of the heating process on the preservative properties of pickled cucumber,pickles using a traditional Cambodian were prepared. While the products that did not undergo theheating process were highly contaminated by microbes, the products prepared with the heatingprocess did not show the presence of coliforms, E. coli, yeasts, and molds for 7 days at 30 °C. This
result showed that the heating process killed many spoilage microbes, including foodborne pathogens.
The heating process is considered to be effective in providing safe products and extending shelf life.
Sensory evaluation tests were conducted in Cambodia. From the results, there was the possibility ofacceptance of the pickled cucumber prepared with the heating process by the Cambodian people.
There were comments from panelists that further improvement in the softness of the pickles wasneeded.
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