Revisiting The Fermented Vegetables In China: Evolution From Traditional Practices To Functional Gain

Jingru Zhou, Shenghan Gao, Shuhui Wan, Rongzhen Jiang , Kiran Thakur. School of Food Science and Engineering, Hefei University of Technology, Hefei 230009, People’s Republic of China

2018-09-08 12:26:44



Approximately 3,000 years ago, Chinese farmers discovered the fermentation which has long been practiced to convert agricultural commodities into foods with an intend of long time preservation. The present era of functional foods evolution truly takes us back to the early traditional practices which have laid the foundation for the present growth in food fermentation industries worldwide. It is believed that fermentation was preferably used to preserve fruits and vegetables for times of scarcity by preserving the food by organic acid and alcohols, impart desirable flavor, texture to foods, reduce toxicity, and decrease cooking time.

Several fermented fruits and vegetables products have a long history in human nutrition from ancient ages and they are associated with the several social aspects of different communities. The production methods of different traditional fermented foods remained unknown and passed down to subsequent generations as family traditions. With the time, understanding of these processes and their adaptation for commercialization have improved. Food researchers are emphasizing on the tremendous scope and potential to exploit the micro-organisms for meeting the growing world demand for food, through efficient utilization of available natural food and feed stocks and the transformation of waste materials. The recent research programmes on fermented vegetables facilitate an understanding of the diversity in microbial profiles and fermentation pathways involved in the production of fermented vegetables, which establishes a basis for optimally selecting microorganisms to manufacture high-quality fermented vegetable products, and lays the foundation for better utilizing tropical microbial resources.

As the human population is expanding, lactic acid fermentation seems to be an important method for preserving various food items for feeding the ever increasing generations. Due to advances in fermentation process and resulting metabolites, Lactic acid bacteria (LAB) have evolved from starter cultures to cell factories. The fermentation of plant substrates relies on the ability of LAB to rapidly adapt and metabolize the available nutrients. The specific traits of LAB for their adaptive growth and survival strategies during plant fermentation have been unraveled, which allow the optimal design of fermentation process for a particular substrate. LAB can attach to the surface of vegetables, fermenting sugar, and other nutrients to produce lactic acid. Fermented vegetables have the nutritional and healthy functions necessary to adjust the balance between intestinal microbiota and making these vegetables essential for consumers. Although, fermented vegetables have been prepared and consumed throughout history by people all over the world. The present article gives us the idea about how does ancient China portrait the origin of fermented vegetable production and their consumption?  Lacto fermented cabbage was already known in China some 6,0000 years ago and served as a staple food for those who built the Great Wall of China. Today the dish known as "Sauerkraut" is still the German national dish. Because of the immense importance of indigenous fermented fruits and vegetables in food preservation and their potential to contribute to the growing food needs of the world, it is essential that the knowledge of their production is not lost. There is a continuous danger that the introduction of 'western foods' with their glamorous image will displace these traditional foods. The introduction of imported fermented vegetables products especially processed ones, radically changed the Chinese food culture into a mixed grill of both foreign and local dishes. Almost in contrast, many of the local indigenous fermented vegetables are getting rejected due to lack of appeal. The current generation people prefer the imported and exotic food items because of the attractive form, long shelf life, ease of transportation and other forms of utility which consumers associate with them. In the light of above limitations, several traditional fermentations from Asia have been upgraded to high technology production system because of the extensive research taking the hold for fermented food technology.

Importance of fermented vegetables in Asia

Fermented vegetables are one of the oldest vegetables processing and storage methods in China and other Asian countries. Because its processing method and equipment are simple and easy to use, the raw vegetables materials can be used to develop many unique products in different regions. The original idea of fermenting the vegetables was not to turn them into pickles, but for their long term storage. At that time, unlike today's technology and rapid transportation, many vegetables could not cross the seasonal and regional barriers and become dishes on the table. During early days in Chinese history, farmers harvested  many vegetables and ate them in the fields during summer season. On the other hand, in winters, there was scarcity of food. In those days, to preserve the left over vegetables for cross season specially in winters was the only purpose behind fermentation. Altogether, fermented vegetables have diverse traditions and cultural beliefs depending on the geographical areas. Gradually, this practice became so popular which has enabled Chinese ancestors in temperate and cooler regions to survive during the winter season and those in the tropics to survive drought periods with enough food on their tables. Likewise, production methods of different traditional fermented foods were passed down to subsequent generations as family traditions. With the continuous improvement of the modern living standards, people's life structure has changed greatly. Modern people eat fermented foods no longer to solve the food crisis, but in order to improve the taste and texture, easy digestion, and impart various health benefits. The traditional fermentation process is natural fermentation, usually fermented by multi strains. The synergy of these microbes gives the unique aroma, texture, color and taste of Chinese fermented food, which makes it native, rich in nutrients with unique health value. Mold, yeast, lactic acid bacteria and Acetobacter are the main fungi in the fermentation process. The traditional fermentation process is simple and varies for each kind of raw material. The method of inoculation is divided into two kinds; one is to mix with other substances and then add microorganisms to carry out fermentation, or fermentation with a series of microbes and the other one is to ferment in the open air and the microbial community in the material itself, such as the fermentation of flour and the fermentation of wine. Traditional fermentation represents spontaneous fermentation which is neither predictable nor controllable. With the times, optimization and control measures in the food characteristics have improvised the most inoculated fermentations by using pure cultures as starter inoculums which results into known high-quality products with selective metabolite production as per the requirement.

Cultural Connection

Talking about cultural historical connection, fermented vegetables are the crystallization of the wisdom of the ancient people working throughout.  Moreover, this kind of food is also very representative, it can represent China's food culture. In recent years, food safety problems have emerged in China, therefore, more emphasis should be given on management, especially on fermented foods such as cereal. The market demand for cereal products is too large, so if there is a problem, the consequences are absolutely beyond our imagination. In the era of functional foods, consumers are very vigilant while choosing their health foods. If the food safety of traditionally fermented vegetables is not taken seriously, imported fermented vegetables may dominate the market potential of Chinese traditional fermented vegetables. The production atmosphere has to be improved in terms of raw material quality, hygiene, containers, and the place of storage.  Fermented foods are one of China's ethnic foods spread by hundreds or even thousands of years, but with the increase of market demand, there are many obvious problems in Chinese fermented food, for these problems should be timely put forward with quality control measures, to ensure the prospects for Chinese fermented food. The Pickled cabbage is a staple food in the Northeast China. Due to the long winter time, fresh vegetables are not suitable for storage in northeast and north China. Fuling zhacai, chongqing Fuling district specialty, national geographic symbol products. Fuling zhacai selected fuling special rapeseed head, through the unique processing technology made of fresh tender fragrant crisp flavor products. It is also one of the three famous Chinese export vegetables (pickled cabbage, millet, and bamboo shoots). Its traditional production techniques have been included in the second batch of national intangible cultural heritage list. Yangzhou pickles is a special traditional pickles dish produced in yangzhou area of Jiangsu province. Yangzhou pickles have a long history and were invented in the Han dynasty. Yangzhou pickles have milk cucumber, pagoda vegetables, turnip heads, tender ginger, sweet pickles melon and other dozens of specifications. Sichuan Pickles is a vegetable product made from fresh vegetables or vegetable salted billets, fermented with salt or salt water, seasoned and processed. Sichuan pickle craft inherits a thousand years, the characteristic is outstanding. Sichuan kimchi is known as the "Sichuan cuisine’s bone". Sichuan cuisine is one of the eight famous cuisines in China.

Future Perspectives

Fermentation of vegetables is a well-established part of the human diet since time immortal; nevertheless, less appreciated and without complete understanding of their underlying microbial functionality, till date. Bioprospecting the native starter cultures and their characterization can aid to the development of large-scale and controllable production of Chinese fermented vegetables products without the loss of unique flavors and particular characteristics. The dominant selected species obtained from traditional fermentation can replace the long old unknown inoculums with excellent viability throughout the fermentation. In case of mixed fermentations by different combinations of dominant species, the synergetic effects imparted by each individual species can be studied to regulate the better fermentation process. The prolific starters which has been used since ages can be preserved in culture depository and their functional aspects can be explored in high tech laboratories engaged in food science research. The microbial diversity of some famous fermented vegetables can be another area to correlate their functional health values with individual strain species. Fermentation can be affirmed as the most modest process which uses no energy and is entirely natural—is one practical way we can reverse the trend, reclaiming both our heritage from the past and the climate for the future. The expediency of bacterial fermentation is that all these bacteria need is sugar to ferment. Different ethnic groups contributed equally for development of fermented vegetables, and individual communities introduced unique flavors and traditions that were part of their culinary heritage. These unique practices gave rise to diverse fermented vegetables and even their consumption pattern varied from place to place. The great historical contribution by Chinese ancestors is marked by the fact that how foods were unknowingly subjected to natural microbial fermentation. Without knowledge of microbes or fermentation process, our ancestors recognized the various functional qualities of fermented foods and due to the establishment of this early wisdom traditional foods are experiencing a burst of popularity as health foods worldwide. Since then, the fermentation has received much attention for purposeful application to provide value in the areas of human nutrition, traditional medicine, and culture (ceremonies, and so on). In general, traditional fermented foods produced with indigenous practices throughout the world were made under primitive conditions, which resulted in low yield and poor quality. Fermented foods play an important socio-economic role in developing countries as well as making a major contribution to the nutrition requirements of natural populations. The article offers a holistic view that would help to identify the checkpoints for fermentation improvement with future prospects. Due to multi-faceted effects of LAB and improved fermentation process, the traditionally fermented vegetables can be well recognized  as "Ancient Foods for the Modern Guts". This is the high time to get out of the pickle jar!

Prof. Keith H. Steinkraus (Cornell University, 1993) very rightly stated that ‘The processes required for fermented foods were present on earth when man appeared on the scene. "When we study these foods, we are in fact studying the most intimate relationships between man, microbe and foods."