Course:FNH200/2012w Team11 Kimchi

All kinds of kimchi varieties. (Photo by by Martin Roell)

Introduction

Kimchi ingredients and two different types of kimchi. (Photo by LWY at flickr)

Kimchi, a common traditional Korean side dish, is a fermented vegetable product that is prepared mainly from mixed vegetables with different types of additional ingredients and spices; it can also be served as a main course (ie. kimchi tofu soup, bibimbap, etc) .The different varieties are due to the raw materials used, processing methods, seasons, areas, and functional properties of kimchi. Approximately 2-3 days of fermentation driven by microorganisms in these raw ingredients gives the best taste of the kimchi at optimal pH (4.2-4.5) and acidity (0.6-0.8%).

According to the historical documents, there has been number of name changes starting from shimchae (salting of vegetable) which went through some phonetic changes: shimchae – dimchae – kimchae – kimchi. During the cold winter months, when cultivation was practically impossible, people developed a new storage method known as ‘pickling’. Before the 9th century, it was just a pickled vegetable until people started to use a selection of seasonings and spices. Red chili pepper was not used for seasoning until the 17th century, when it became a major ingredient in kimchi, thereafter.

Production and Processing

The ingredients and procedures involved in kimchi production and processing are simple and easy to learn.

Ingredients

• Napa cabbage,radish, carrots and broccoli
• Garlic, ginger and green onions
• Sea salts, fine red chili powder
• 1/2 ripe apple, 1/2 ripe pear, 1/2 yellow onion
• 2 tablespoons fish sauce (optional)

Functions of Ingredients

• Vegetables

1. the source of indigenous microorganisms (the lactic acid bacterial)
2. the source of carbohydrates for kimchi fermentation, as the sugars from these raw materials are converted into lactic acid

• Garlic, ginger and green onions

1. flavouring
2. bactericidal and sterilizing roles due to sulfur and propylene compounds from these ingredients
3. delay fermentation to prolong the storage capacity

• Salts

1. flavouring
2. promote the growth of lactic acid-producing bacteria
3. reduce the water activity (Aw) and the moisture content (10-20%) of the ingredient mixture to inhibit the growth of normal spoilage- and disease-causing microorganisms, and to control the growth of other undesirable microorganisms
4. draw water-soluble nutrients from tissues of vegetables making them available for fermentative microorganisms

• Red chili powder

1. flavouring
2. promote the fermentation of kimchi
3. bactericidal and sterilizing roles

• Blend of apple, pear and yellow onions

1. natural sweetener to the kimchi instead of using sugar

• Fish source

1. rich in proteins and amino acids
2. improve the sensory quality of the kimchi

Procedures

1 Preparing ingredients

• tear off bigger cabbage leaves and chop them into bite-size (~ 1lb)
• chop radish, carrots and broccoli into bite-size (~ ½ lb)
• minced garlic (1 tablespoon)
• minced ginger (1 tablespoon)
• 3-4 sliced green onions
• blend of apple, pear, yellow onion and 1 cup of water
• a bowl of sea salt solution ( ¼ cup sea salt)
• a chili paste ( ¼ cup of fine red chili powder dissolved in water)

2 Salting the napa cabbage

• pour sea salt solution over cabbage leaves and soak them in salt water for couple hours
• then gently rinse off salt water from the cabbage leaves and transfer them into a large bowl

3 Ading spices

• add red chili paste
• add minced garlic, ginger, and green onions
• add apple/pear/ yellow onion blend
• add fish sauce (optional)

4 Mixing and mashing

• thoroughly mix everything together with plastic gloves, especially the red chili paste
• mash the mix to get some juices from the ingredients (the juices occupy the air spaces among ingredients, creating the anaerobic environment)

5 Fermentation

• transfer everything into a glass jar with a water/air lock on top; filling the jar 80% as kimchi will expand
• allow 2 to 3 days of fermentation at room temperature (20 ℃)
• then put the glass jar into refrigerator for continuing fermentation

Packaging

Some people make kimchi at home and some people buy kimchi from the store. When kimchi is made at home, it is often stored in a jar or a container. The process of making and storing kimchi in Korea is called "gimjang." Gimjang season is mostly in November because massive harvests of cabbages, radishes, green onion and Indian mustard leaves happen. The containers in which kimchi are stored are tightly sealed in order to prevent oxygen exposure - kimchi is often overripened by carbon dioxide gas. Even after kimchi fully ripens, Lactobacillus strains - lactic acid bacteria, the primary culture of fermentation in kimchi - continue to grow and undergo acid-producing reactions, which will slowly break down the food. This process is called “over-ripening,” when polygalactulonaze enzymes break down pectin in the vegetable ingredients, causing kimchi to soften. Thus, fermentation of kimchi at room temperature for long periods of time are avoided. Kimchi should not be left at room temperature for more than two days and then be moved to a cooler area, such as the refrigerator. The type of container does not affect the properties of kimchi because it is generally unaffected by large changes in the environment; therefore, kimchi can be stored in glass jars, Styrofoam boxes, or plastic container. Specialized sterilization processes are not required. Nevertheless, storage in clay pots is highly recommended for the duration of fermentation as clay pots have water-sealed locks to seal in the smell and to keep out the air. Once kimchi is stored in the refrigerator, it can be stored for several months. In Korea, people own specialized fridges for kimchi and this appliance provides a controlled atmosphere for all types of kimchi. In addition, it includes temperature control and different fermentation processes. One of the reasons that households use kimchi refrigerators rather than conventional fridges is because kimchi refrigerators use a direct cooling system that maintains constant temperature and humidity; whereas, the conventional refrigerators use an indirect cooling system, in which chilled running water lowers the surrounding temperature. Refrigerators specialized for kimchi is a contemporary method. Some households in Korea still keep to traditional methods; they store kimchi in large clay pots, which is then planted underground. Storing clay pots underground provides the right temperature for kimchi. The storage temperature must be well controlled to avoid excessive fermentation and to keep the delicious taste.

Traditional way of storing kimchi. (Photo from OlkhichaAppa)

When not making Kimchi at home, many people buy Kimchi from the store. The most effective method for Kimchi packaging is called “vacuum packaing”, which seals the Kimchi by sucking all the oxygen out in order to maintain Kimchi fresh. In order to maintain kimchi in a long period of time, it prevents oxidation, dampening and mould growth. Making kimchi involves adding vegetables, so when companies prepare packaging, they need to seal their products well in order to prevent the smell, dampening and oxidation. If the kimchi plants do not use the right method for packaging, microorganisms can grow within the kimchi. Mould is caused when the moist vegetables are exposed to the air, and it can be prevented if they ensure that the vegetables remain completely submerged in the brine liquid and when it is kept in the tight seal.

Regulations

Depending on the manufacturing company and the type of kimchi, it may either be made in Canada or be imported from Korea as the whole, finalized product. For the purposes of this assignment, we will assume that each ingredient is gathered in its own, purified entity in Canada before being made into kimchi. Several of the ingredients listed below are either not grown in British Columbia or are imported from other countries, subjecting them to the Import and Interprovincial Requirements of the Canada Agricultural Products Act: Fresh Fruit and Vegetable Regulations.

Canadian Import Requirements

A Canadian importer is required to hold a license with the Canadian Food Inspection Agency (CFIA) or be a member of the Dispute Resolution Corporations. Under the Fresh Fruit and Vegetable Regulations, a number of products are subject to a minimum grading standard that must be met. Apples and potatoes are the exempt from this law, requiring them to meet the highest grade standards established in Canada: apples must meet Extra Fancy or Fancy Grade, and potatoes must meet Canada No. 1. In addition to the grading standards, apples, potatoes, and onions from other countries must receive an inspection certificate from the CFIA upon arrival to meet the minimum Canadian import requirements for quality, labelling, and packaging. Prepackaged fresh fruits and vegetables must be labelled with the information required under the Consumer Packaging and Labeling Regulations.

Fresh fruits and vegetables with established grade standards:

Fruits

Vegetables

1. Apples 2. Apricots 3. Blueberries (exception: for processing) 4. Cantaloupes 5. Cherries 6. Crabapples 7. Cranberries 8. Grapes 9. Peaches 10. Pears 11. Plums and prunes 12. Field rhubarb 13. Strawberries

1. Asparagus (exception: white asparagus) 2. Beets (exception: beets with tops) 3. Brussels sprouts 4. Cabbages 5. Carrots (exception: carrots with tops) 6. Cauliflower 7. Celery 8. Sweet corn 9. Field and greenhouse cucumbers (exception: field pickling cucumbers) 10. Head lettuce 11. Onions (exception: onions with tops) 12. Parsnips 13. Potatoes (excluded if certified for seed) 14. Rutabagas 15. Field and greenhouse tomatoes (exception: field cherry tomatoes)

Picture of the Napa cabbage. (Photo by Forest & Kim Starr)

Napa cabbages

Napa cabbages, or Chinese cabbages, proliferate in cool weather—the optimal temperature is between 13 and 15℃. They are best grown on firm soil with high nutrition and moisture content. Although the ideal pH of the soil is 7.0, Chinese cabbages still thrive between a pH range of 5.5 to 7.6. Due to the specificity of these environmental factors for optimal growth, napa cabbages used in the making of kimchi in British Columbia are either shipped from Southern Ontario or imported from Seattle or Los Angeles.

There are two grades for cabbages in Canada: Canada No. 1 and Canada No. 2. For all grades, the cabbages must be properly packed with similar characteristics (trimmed butts that are less than 13 mm; less than six wrapper leaves per head; heads that are not withered or burst; heads that hide the formation of a seed stem) and be free from decay. In addition to meeting the aforementioned standards, Canada No. 1 cabbages must have all damaged outer leaves be removed, be completely void of all defects that affect the appearance or edibility, and be packaged with other cabbages that vary less than 51 mm in diameter. Canada No. 2 cabbages must have firm heads and must be free of any defects that seriously alter the appearance, edibility, or shipping quality of the cabbages and these defects must be removable with the loss less than 15% of the entire vegetable. At the time of shipping or repackaging, the above standards for the grades are considered to be met if less than 10% of the products in the shipping container have defects.

Carrots

The grade standards for carrots are applicable to the species Dacus carota, with the exception of carrots with tops. Canada No. 1 and Canada No. 2 are the two grades for carrots in Canada. For all graded carrots, they must be over 114 mm, be properly packed, not be forked, retain their crowns, and be free from decay as to avoid soft, shriveled, or flabby texture. The largest differences between Grade 1 and Grade 2 carrots are the requirements for less harmful defects, a smaller percentage of damage on the overall product, and the size standards. As long as the other standards for texture and appearance are met, No. 1 carrots can be divided into groups according to their diameters (minimum 19 mm; minimum 25 mm and maximum 44 mm; or a minimum of 38 mm in diameter), while No. 2 carrots simply must have a minimum diameter of 19 mm, while also possessing other qualities of a Grade 2 product.

Onions

The grade standards for onions are applicable to the species Allium cepa, where green onions and onions with tops are excluded from this classification system. There are three classes of onions in Canada: Canada No. 1, Canada No. 1 Pickling, and Canada No. 2. All commercially sold onions must be free of thick necks, seed stems, and decay. The primary difference between No. 1 onions and the lesser grades is the date of harvesting; products picked before September 16 of their harvest year may depress slightly to moderate pressure and must be cured so that the neck is moderately dry. Onions harvested after September 15 must be completely firm and dry to touch. Onions of the Canada No. 1 Pickling grade only differs from the highest class by the negligibility of the harvest date and their allowance for surface discolouration. Canada No. 2 onions can be of ovoid form and have multiple centers of growth unlike the more superior grades.

Apples and Pears

Apples and pears are often optional ingredients in kimchi that are used to add additional flavouring and to replace sugar. There are seven different grades of apples in Canada: Extra Fancy, Canada Fancy, Canada Commercial, Canada Hailed, Canada Commercial Cookers, Canada No. 1 Peelers, and Canada No. 2 Peelers. Apples are divided according to their shape, colour, pattern of colour, and the type and amount of damage. Pears can be divided by their physical characteristics into three different categories: Canada Extra Fancy, Canada Fancy, and Canada Commercial. The type of defect, presence or absence of stem, amount of discolouration, and the smoothness of the peel contribute to the division of pears.

Nutrition and Health Benefits of Kimchi

Kimchi has been named one of the top five healthiest foods in the world by Health magazine in 2008. In addition to containing low calories (18kcal/g), kimchi is very beneficial for human health as it has high levels of vitamins (vitamin C, beta carotene, and vitamin B complex), minerals (sodium, potassium, calcium, iron, and phosphorous), and dietary fibers. The following table lists several functional characteristics of kimchi, several of which will be elaborate upon.

Functional Characteristics of Kimchi
Promotes weight loss Decreases body fats Prevents constipation Good source of probiotics Antiatherosclerotic effects Antioxdative effects Anticancer effects Enhances immune function

Controlling body weight

Kimchi is an excellent food for diets that is low in carbohydrate and lipids, and has demonstrated the capability to control body weight in rats. This is regulated primarily through the chemical capsaicin in red pepper, an essential ingredient of kimchi, which gives the dish its characteristic, spicy taste. Capsaicin stimulates the adrenal glands to release catecholamine, which increases body metabolism (digestion and breakdown of molecules) and the expenditure of energy. Red pepper powder also increases the lipolytic activity of adipocytes, allowing fats to be broken down at a more rapid rate. Capsaicin has a synergistic effect in weight loss when used in kimchi due to the addition of other ingredients, such as garlic and onions. Moreover, kimchi fermented at optimal conditions (6 weeks for 4℃) reduces the number of and the subsequent lipid accumulation by adipose cells.

In the study with rats, four groups of rats were fed different diets for four weeks: normal diet; high-fat diet; high-fat diet with red pepper flakes; and high-fat diet with kimchi containing the same amount capsaicin as the diet with red pepper flakes. Kimchi-added high fat diet resulted in the greatest weight loss through the reduction of the size of fat cells. Kimchi’s control of weight loss has been reflected in humans through two further studies that combined a kimchi-based diet with exercise. The daily intake of 3 g of freeze-dried kimchi, which is equivalent to 30 g of fresh kimchi, coupled with an hour of exercise of moderate intensity significantly lowered body mass index, fat mass, abdominal fat, and triacylglycerol (fatty acid polymers) concentrations in the blood, while increasing the level of high-density lipids.

Figure A shows an artery with normal blood flow. Figure B shows an artery with plaque build-up and restricted blood flow.

Antiatherosclerotic effect

Atherosclerosis is a condition that leads to narrowing of the blood vessels due to the build up of lipid plaques, which result in blood clots. Kimchi reduces the risk of atherosclerosis by decreasing the levels of low-density lipid (LDL) cholesterol, while simultaneously increasing high-density lipid (HDL) cholesterol. Low-density lipids are also known as “bad cholesterol” as it is the primary agent in the formation and growth of lipid plaques in blood vessels. As lipid plaques gradually build up over time, they can completely block blood vessels, preventing the flow of oxygen or causing the vessel to rupture. Atherosclerosis often results in heart attacks due to reduced blood flow the heart. High-density lipids, or “good cholesterol” pick up free LDLs from the blood and return them to the liver, where they are metabolized, thus reducing plaque development.

Kimchi diets result in feces with higher triacylglycerol concentration, illustrating that kimchi increases lipid use and metabolism from adipose tissues and stimulates the excretion of lipids through feces. The high levels of fiber in kimchi may also aid in immobilizing and eliminating LDL cholesterol. Fermented kimchi has been shown to have higher immobilizing effects on lipids, indicating that the fermentation process produces more functional components that capture fatty acids than raw kimchi.

Antioxidative effects

The antioxidative effects of kimchi are correlated with chlorophyll, phenol compounds, vitamin C, carotenoids, dietary fibers, and other chemicals that are produced by lactic acid bacteria during the fermentation process. The free radical theory is the one of the most accepted hypothesis that explains the anti-aging activity of kimchi. Free radicals are molecular fragments with an unpaired electron, which are common products of oxidation. The willingness to share this electron makes free radicals highly reactive as they undergo spontaneous reactions with other molecules. Their disruptive effects on normal metabolism make free radicals extremely dangerous and damaging to the body. Antioxidants in the body are often reserved in the body for the sole purpose of removing free radicals; in kimchi, a chemical known as dichloromethane exhibits the highest antioxidant effect against the oxidation of low-density lipids.

In addition to reducing the oxidation rates of low-density lipids, research has shown that kimchi extracts lowers the levels of superoxide anions, hydroxyl radicals, and hydrogen peroxide (H2O2)—all harmful, oxidative chemicals—within the body. Lower amounts of hydrogen peroxide are especially linked with the proliferation of skin cells, such as keratinocytes and fibroblasts. In a study done on hairless mice, a diet of kimchi was found to improve the conditions of the skin, resulting in thicker skin and increased collagen synthesis, which maintains skin elasticity. The kimchi diet was also found to prevent UV-induced photoaging through antioxidant activities.

Anticancer effects

In 1985, it was initially assumed that kimchi intake was a risk factor for stomach cancer. However, subsequent research clarified that cancer is associated with a diet high in salt, which is concentrated in fish sauce that are used during the making of kimchi.

Kimchi has not only been found to decrease the rate of mutations, but has protective factors against cancer as well. The dichloromethane fraction, which is also an oxidant, aids in anticancer activity, as well, by preventing DNA synthesis of cancer cells.

Sensory Aspects

Generally, kimchi is red-orange in color, tastes spicy, and has a strong smell. However, the flavour and the appearance of kimchi varies according to how much red chili powder and salt are added in.

Appearance Factors

Usually, the white and green colors of the napa cabbages are overwhelmed by the redness of the red pepper flakes. The cabbages are usually cut into chunky sizes.

Textual Factors

The fermentation process and the addition of salt softens the cabbage leaves.

The already cut vegetables are crunchy and are relatively juicy due to the spicy sauce that was absorbed during dehydration by salt and fermentation.

Flavour Factors

Kimchi is a combination of a spicy, pungent odor and a very deep, rich flavour. At the onset, the spicy flavour prevails after chewing and swallowing due to the chili sauce that has been absorbed into each piece of cabbage. The level of spiciness rises the more you eat.

Powerful combination of all ingredients: Salty, sour (due to fermentation), fresh, spicy and a touch of sweet (from fish sauce).

Fermentation produces amino acids and lactic acids where both combined together to produce the special flavor of kimchi.

Although kimchi has a lot of chili pepper flakes in it, its strong taste and smell come mostly from natural yeasts and bacteria that develop over time in the mixture of vegetables in the pot.

Unique

It is unique everytime you make it as it is hard to duplicate the exact conditions of fermentation, the precise amount of ingredients used, and the process of mixing is not always exactly equal. Each piece of kimchi you taste is unique and special.

Survey

Regarding the preference of kimchi, hot and spicy (66%) was mostly preferred, followed by not sweet (55%), not salty (47%), and a little ripe (46%).

Variety

Kimchi can be categorized by main ingredients, regions or seasons. Some of the most common varieties are described here:

Several ingredients blended inside each layer of the Napa cabbage. (Photo by Catherine Ling)

Baechu Kimchi (Napa Cabbage Kimchi)

• The most common variety and most common during the fall season.
• Main ingredient=Napa cabbage.
• Prepared by inserting sok (blended stuff materials) in between layers of the Napa cabbage.
• The ingredients of sok depend on different regions and weather conditions, which often include thin strips of radish, parsley, pine nuts, pears, chestnuts, shredded red pepper, manna lichen, garlic, and ginger.
• Traditionally, has a very strong salty flavor, but due to health concerns, low-sodium kimchi is preferably made both in homes and the manufacturing industry.

Chonggak Kimchi. Notice the ponytail shaped-like pieces of radish.(Photo by Kattebelletje)

Chonggak/Radish Kimchi (Bachelor Kimchi)

• Very popular summer kimchi.
• Consist of radish and turnip greens.
• One of the easiest to make since it does not need to be fermented for a long period of time.
• Name: “chonggak”=hairstyle of unmarried Korean men; therefore, also called Bachelor Kimchi since it resembles men’s hair style (they used to wear special hairstyles that is shaped like a radish).

Dongchimi.(Photo by Karendotcom127

Dongchimi

• Name: “dong”=winter, “chimi”=ancient term for kimchi.
• Traditionally consumed during the winter season.
• Consists of daikon, baechu (Chinese cabbage), spring onions, fermented green chili, ginger, bae (Korean pear), and watery brine.
• Fermented like others, but the maturing period is relatively short (only 2-3days).
• The clear, clean taste of watery dongchimi is usually used in cold noodle soup or served with steamed sweet potatoes to balance out the rich flavours.
• Sometimes called "radish water kimchi".

The perilla leaves used to make the kimchi. (Uploaded by Ies)

Kkaennip Kimchi

• Features layers of perilla leaves marinated in soy sauce and other spices.
• Great as a side dish or added as seasoning to any leaf wrap style meal.

Yeolmu Kimchi (Young Summer Radish Water Kimchi)

• Made during the summer because it requires a type of radish green that is only available during that season.

Kkakdugi Kimchi. (Photo by Ayustety)

Kkakdugi Kimchi (Cubed Radish Kimchi)

• Usually contains all the ingredients found in kimchi, except Napa cabbage is substituted with Korean white radish.
• Sweeter and firmer in the winter.
• Add green radish leaves, green onions, or outer leaves of Chinese cabbage to enhance the flavor.
• Fermented shrimp is added instead of anchovy paste resulting in a darker color and stronger scent.

Pakimchi. (Photo by Karendotcom12)

Pakimchi

• Made up of medium-thick young green onions with the large white part commonly used for the sweet flavor.
• Salted anchovies added to make a strong hot, spicy, and salty taste.

Cucumber Kimchi. (Photo by World to Table at Flickr)

Oi Sobagi (Cucumber Kimchi)

• Most popular during the spring and summer time.
• Juicy and crunchy texture.
• Made with fermented cucumbers along with other vegetables (depending on personal preference).
• Young radish is put between the layers to give a better taste and to build up more volume.

Buchu (Leek) Kimchi

• Popular in Cholla and Kyongsang Provinces (Southern part of South Korea).
• Good appetite stimulant during the summer with its unique flavor and taste.
• Anchovy juice is used for salting.
• Red chili, garlic, sugar, and sesame seeds are added as the seasonings.
• This type of kimchi usually goes well with smoked and roasted meats.

Summary

From the nutritional point of view, kimchi is low in calories, carbohydrates and fats, and contains high levels of dietary fibre, vitamins and minerals. In addition, lactic acid bacteria (the major microorganism) responsible for fermentation, are of high value in terms of its ability to produce antimicrobial agents in order to inhibit pathogenic species, to protect against colon cancer, and to control tumors.

Potential Exam Question

Briefly describe the functions of the following ingredients in kimchi,including: 1) vegetables 2) garlic, ginger and green onion 3) salts 4) red chili powder 5) blend of apple, pear and yellow onions.

Instead of using sugar, what type of natural ingredients can we use to sweeten the kimchi?