• Current Research on Agriculture and Life Sciences
• /
• v.25
• /
• pp.25-31
• /
• 2007

The several enzymes reaction which involve the quality change of fresh vegetables, such as chlorophylase, polyphenol oxidase, lypoxygenase, C-S-lyase, myrosinase and enzymes related lignification were reviewed. Numerous enzyme reaction continuously proceeds to the deterioration of vegetables after harvest due to the respiration and biochemical metabolism reaction, especially in case of physical injuring. It is extremely important to inhibit and to control these enzyme reaction in order to maintain the organoleptic and nutritional quality of fresh vegetables.

• Journal of the East Asian Society of Dietary Life
• /
• v.24 no.1
• /
• pp.28-41
• /
• 2014

The distinctive physiological effect of dietary fiber in the body were studied according to contents and characteristics of each fiber component. In the present study, the composition of fiber in vegetables was investigated, and the effect of heat treatments on fiber content was studied. Contents of total pectin were 0.89~2.75 g/100 g on dry weight basis, with most contents from 1~2 g/100 g. The hot water soluble pectin (HWSP) content of vegetables ranged from 0.33~0.98 g/100 g, sodium hexametaphosphate soluble pectin (HXSP), from 0.29~0.81 g/100 g and HCl soluble pectin(HCLSP), from 0.30~1.40 g/100 g. HCLSP showed the greatest variation according to the type of vegetables. Every vegetable types showed similar contents of these three pectic fractions. Fiber contents of vegetables ranged from 8.8~23.8% for cellulose, 0.6~10.6% for hemicellulose, 1.0~5.2% for lignin, 10.9~25.4% for acid detergent fiber (ADF) and 11.8~31.9% for neutral detergent fiber (NDF) on dry weight basis. Especially, peppers showed higher contents of NDF than the other vegetables. It was found that a great portion of NDF, which is total insoluble dietary fiber, was composed of cellulose since cellulose constituted 63% of NDF. Heat treatment reduced total pectin content in all vegetables regardless of the heating methods and the greatest reduction was observed upon boiling. HWSP content increased, whereas HXSP and HCLSP contents decreased. Heat treatment increased the NDF, ADF and cellulose contents, and most changes were due to changes in cellulose content. The values of hemicellulose and lignin showed irregular pattern upon heating. Contents of total dietary fiber (TDF) were 1.20~7.11% on fresh weight basis. Garlic, edible burdock and pepper leaf showed higher contents of TDF than other vegetables. It was found that a great portion of TDF was composed of insoluble dietary fiber.

• Journal of Food Hygiene and Safety
• /
• v.31 no.6
• /
• pp.393-398
• /
• 2016

The objective of this study was to isolate pathogenic Escherichia coli from fresh vegetables with selective media and Petrifilm, and identify a suspicious colony using biochemical identification. Twenty gram of lettuce, twenty gram of cabbage and ten gram of sprout were prepared, and a 5-strain mixture of pathogenic E. coli (Enterohemorrhagic E. coli NCCP11142, Enterotoxigenic E. coli NCCP14037, Enteropathogenic E. coli NCCP14038, Enteroaggregative E. coli NCCP14039, Enteropathogenic E. coli NCCP15661) was inoculated to obtain 1, 2 and 3 log CFU/g. Eighty to ninety milliliter of buffered peptone water (BPW) was placed and pummeled for 60 s. As a results, the Petrifilm method was all positive, but enrichment method of qualitative analysis was negative except for 3-log CFU/g inoculated lettuce. Regarding biochemical identification of pathogenic E. coli, the identification rates were dependent on type of methods and vegetables; lettuce: API 20E 100% (44/44), Microgen GNA 100% (44/44) and Food System 66.7% (10/15), cabbage: API 20E 64.7% (22/34), Microgen GNA 50% (16/32) and Food System 60% (9/15), sprout: API 20E 65.1% (28/43), Microgen GNA 62.3% (27/43) and Food System 53.3% (8/15). These results could be useful in determining an appropriate method to detect pathogenic E. coli in fresh vegetables.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.7
• /
• pp.367-373
• /
• 2016

This study was performed to set a limitation rule to the UV sterilization process for green vegetable juice containing barley sprouts. The main constituents of the green vegetable juice, viz. barley sprouts, organic Angelica keiskei, carrots, organic dandelion, kale, wild parsley, Angelica keiskei and cabbage, were provided by the CSJ company located in Jincheon, Chungbuk, from December 1st, 2015 to March 1st, 2016. Our manufacturing process followed the general manufacturing process of a general green vegetable juice manufacturer. Table 1 shows the mixing ratio for the green vegetable juice. This green vegetable juice includes 18% vegetable sprouts, 3% barley sprouts, 18% angelica utilis makino, 1% orange concentrate, 4% apple concentrate, 6% fructooligosaccharide, 10% vegetable fermentation juice, 0.4% lemon concentrate and 39.6% purified water. We conducted UV sterilization at levels 10, 8 and 5 with powers of 230W, 320W and 320W, respectively. The UV sterilization was conducted twice at 25Hz and then once at 40Hz. In the bacterial tests after sterilization, the number of bacteria in the dandelions decreased from $2.56{\times}10^8CFU/mL$ to $5.96{\times}10^3CFU/mL$. In addition, no food poisoning or coliform bacteria were detected. Thus, this study provides the information required for setting a limitation rule using bacteria tests in the UV sterilization process for green vegetable juice.

• Journal of Food Hygiene and Safety
• /
• v.27 no.1
• /
• pp.24-29
• /
• 2012

A total of 187 samples of leafy vegetables and fruits were acquired at traditional markets and department stores in Seoul, Korea. Samples were tested for microorganism distributions and for the presence of pathogenic bacteria. The aerobic mesophilic counts ranged between 2.5 and 9.4 log CFU/g, with the highest count recorded from the dropwort. Counts of psychrotrophic microorganisms were as high as those of the mesophilic microorganisms. Total coliform populations between 1.0 and 7.8 log CFU/g were found in 90.9% of the samples. Microbiological counts for fruits were very low. $Escherichia$ $coli$ was isolated in 24 (12.8%) samples. $Staphylococcus$ $aureus$ and $Clostridium$ $perfringens$ contamination were found in 15 (8.0%) and 20 (10.7%) samples. $Salmonella$ species and $Listeria$ $monocytogenes$ were detected in 2.7 and 0.5% of samples, respectively. Among the total 187 samples, 8 samples were contaminated by more than two pathogens. $E.$ $coli$ O157:H7 was not detected in any of the samples. The microbial contamination levels determined in the present study may be used as the primary data to execute microbial risk assessment of fresh vegetables and fruits.

• Korean Journal of Food Science and Technology
• /
• v.25 no.3
• /
• pp.225-231
• /
• 1993

Total dietary fiber and crude fiber contents were analyzed for 54 different kinds of Korean vegetable foods by AOAC method. On the fresh matter basis, total dietary fiber and crude fiber contents of tested food samples ranged from $1.19{\sim}10.35%,\;0.19{\sim}1.28%$ in cereals, $1.12{\sim}1.81%,\;0.29{\sim}0.64%$ in potatoes, $2.05{\sim}18.14%,\;0.38{\sim}4.42%$, in pulses, $0.99{\sim}7.42%,\;0.35{\sim}2.61%$ in fresh vegetables, $2.28{\sim}41.14%,\;0.97{\sim}20.96%$ in processed vegetables, $0.19{\sim}2.91%,\;0.10{\sim}0.79%$ in fruits, $4.27{\sim}10.83%,\;0.96{\sim}4.62%$ in nuts and seeds, $1.62{\sim}3.94%,\;0.79{\sim}0.89%$ in mushrooms, $28.70{\sim}38.19%,\;2.17{\sim}6.41%$ in seaweeds, and $4.65{\sim}6.67%,\;2.49{\sim}3.44%$ in seasonings, respectively. The ratio of total dietary fiber/crude fiber contents ranged from 2 to 13, showing a wide variation among food commodities, necessitating the analysis of total dietary fiber content for individual food items.

• Korean Journal of Food Science and Technology
• /
• v.47 no.2
• /
• pp.184-190
• /
• 2015

We evaluated the effects of three common cabbage cooking methods (blanching, steaming and microwaving) on glucosinolate and S-methylmethionine (SMM) content and total antioxidant capacity of cabbage leaves. We detected four glucosinolates, including glucoraphanin, sinigrin, glucobrassicin, and 4-methoxyglucobrassicin, by high-pressure liquid chromatography (HPLC). Cabbage contained high levels of SMM (192.85 mg/100 g dry weight), compared to other cruciferous vegetables. Blanching cabbage leaves for one to ten minutes decreased glucosinolate and SMM levels, whereas microwaving or steaming cabbage for 5-10 min preserved glucosinolate and SMM levels. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2-2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activities of cooked cabbage generally decreased as cooking time increased, but microwave cooking had a smaller negative effect on antioxidant activities than blanching or steaming. This study demonstrates that some domestic cooking methods, such as microwaving and steaming, can increase the bioaccessibility of glucosinolates and SMM, highlighting the positive role of cooking on the nutritional qualities of cabbage.

• Journal of Food Hygiene and Safety
• /
• v.34 no.4
• /
• pp.374-379
• /
• 2019

This study developed predictive growth models of Salmonella enterica Serovar Typhimurium on lettuce washed with chlorine (100~300 ppm) and ultrasound (US, 37 kHz, 380 W) treatment and stored at different temperatures ($10{\sim}25^{\circ}C$) using a polynomial equation. The primary model of specific growth rate (SGR) and lag time (LT) showed a good fit ($R^2{\geq}0.92$) with a Gompertz equation. A secondary model was obtained using a quadratic polynomial equation. The appropriateness of the secondary SGR and LT model was verified by coefficient of determination ($R^2=0.98{\sim}0.99$ for internal validation, 0.97~0.98 for external validation), mean square error (MSE=-0.0071~0.0057 for internal validation, -0.0118~0.0176 for external validation), bias factor ($B_f=0.9918{\sim}1.0066$ for internal validation, 0.9865~1.0205 for external validation), and accuracy factor ($A_f=0.9935{\sim}1.0082$ for internal validation, 0.9799~1.0137 for external validation). The newly developed models for S. Typhimurium could be incorporated into a tertiary modeling program to predict the growth of S. Typhimurium as a function of combined chlorine and US during the storage. These new models may also be useful to predict potential S. Typhimurium growth on lettuce, which is important for food safety purposes during the overall supply chain of lettuce from farm to table. Finally, the models may offer reliable and useful information of growth kinetics for the quantification microbial risk assessment of S. Typhimurium on washed lettuce.

• Journal of Food Hygiene and Safety
• /
• v.35 no.5
• /
• pp.495-502
• /
• 2020

Processing fresh produce into fresh-cut products increases the risk of bacterial growth and contamination by breaking the exterior barrier of produce. Our objective in this study was to develop predictive models of Listeria monocytogenes in the fresh-cut salad, fresh-cut pineapple, and frozen mango. Predictive growth and survival models were developed to predict the change of L. monocytogenes populations in the fresh-cut salad (4, 10, 12, 13, 17, 25, and 36℃), fresh-cut pineapple (4, 10, 17, 25, 30, and 36℃), and frozen mango (-2, -10 and -18℃) as a function of temperature. The growth of L. monocytogenes in fresh-cut salad and pineapple was observed at above 13℃ and 10℃, respectively. The growth of L. monocytogenes in pineapple was faster than in salad. The delta value of L. monocytogenes in frozen mango increased as the storage temperature decreased. The results indicate that L. monocytogenes behave differently according to the physicochemical properties of fresh-cut fruits and vegetables. Since L. monocytogenes grow and survive well in refrigerated and frozen conditions, management programs and preventive controls for the processing of fresh-cut produce should be effectively implemented to enhance the safety of fresh-cut fruits and vegetables at retail markets.

• Korean Journal of Food Science and Technology
• /
• v.30 no.2
• /
• pp.278-282
• /
• 1998

Peeled garlic, soybean sprouts, cut onion and cut green pepper were treated by dipping in solutions of different antibrowning agents, and then stored at $10^{\circ}C$. Surface color and polyphenol oxidase activity of produce were measured through the storage. Tested antibrowning agents include ascorbic acid, citric acid and allyl isothiocyanate. The commodities showed different responses to the antibrowning agent solutions; 1% citric acid for peeled garlic, 1% ascorbic acid for soybean sprouts, 2% citric acid for cut onion, and 1% ascorbic acid for cut green pepper showed better retardation in browning than the other treatments for respective product. For peeled garlic, surface browning was concomitant with increase in polyphenol oxidase activity during storage. On the other hand, there was no positive correlation between surface browning and polyphenol oxidase activity for the other stored products.