Creative chefs are always looking for ways to add new flavors to their cooking. One theme that has been on everyone’s lips for years now is fermentation. The topic is incredibly broad and relevant. An ancient technique that keeps being reinvented through new ferments and applications.
Humans have been using fermentation for the past ten thousand years. The importance of fermented food in our diet is such that there are around 5,000 known varieties of fermentation known to date.
The science behind fermentation
Fermentation is in essence a transformation of organic raw materials. It has a number of effects: ferments preserve the food by protecting it from attack by pathogens, they change both the nutritional and aromatic properties of ingredients and increase the digestibility of the transformed product.
Fermentation is a preservation method in the sense that ferments create a medium that protects the product from the activities of pathogenic microorganisms. They do so by altering the pH or producing alcohol or acetic acid.
At a microscopic level, raw materials made up of a complex mixture of organic compounds (carbohydrates, proteins, fats) undergo modifications caused by the action of microorganisms and enzymes – the latter being primarily produced by the microorganisms themselves.
Different types of ferments
Lactic acid bacteria are by far the most common ferments. They owe their name to the fact that they alter the pH by acidifying the medium. They generally operate in anaerobic or low-oxygen conditions (just like most fermentations), and enrich the chef’s repertoire by adding a whole range of fresh flavours to the product. Some of the best-known lactic acid fermentations are sauerkraut, kimchi, yoghurt, dry sausages and fish sauces.
The role of salt
While some fermentations use more sophisticated technologies, others use one of the first known techniques, namely salting. Salt has always been a conservation ingredient. It plays an important role in many fermentations.
Think for example of fermented sauces and pastes that are characterized by a high amino-acid and peptide content, meaty flavours and a high level of salt:
– Chinese soy sauce, shoyu and miso in Japan, and ganjang and doenjang in Korea.
– Fish-based sauces: nam pla in Thailand, nuoc mam in Vietnam, patis in the Philippines.
– Fish paste: Kapi in Thailand, Mam in Vietnam, hentak in India and terasi in Indonesia.
Salt also plays a major role in lactic acid fermentations because it creates the right environment for ferments to develop: kimchi, jangajji (using soy sauce for example), sauerkraut, gherkins and other pickles, table olives. But also in lactic acid fermented dairy products: yoghurt, kefir, cheeses; yoghurt- and cereal-based preparations: kishk in Egypt, trahanas and tarhana in Greece and Turkey; mixtures of rice with raw fish or shrimps: balao balao in the Philippines…
Kimchi and jangajji
Asian cooking is strongly influenced by the flavours of fermentation. Fermentation can be found in Chinese, Japanese and Korean cuisine. The latter is gaining more and more traction this in part because of its ability to easily blend with contemporary fast food concepts.
One if the most famous dishes of Korean cuisine is kimchi, the cousin of sauerkraut. But there are other very similar fermentations such as dongchimi or the lesser known jangajji. Jangjji requires a more complex preparation based on a combination of vinegar, sugar and soy sauce (which contains about 30% of salt). It is an interesting technique because unlike kimchi it can be applied to a wide range of ingredients: perilla leaves, ginger, young berries of sansho, blue crab, cucumber, green peppers …
RECIPE: Click here for the onion jangajji recipe.
The processes of kimchi
There are different key processes involved in making kimchi:
– blanching, which limits the microorganisms on the surface of the vegetables and therefore allows fermentation to start with selected bacterial strains (in this case of lactic acid bacteria). This makes it possible to monitor and reproduce the recipe ‘identically’. A mixed, natural bacterial population cannot offer any guarantee of reproducibility because how it reacts and evolves depends on the conditions of the medium. Depending on the conditions some bacteria may grow faster than others.
– preparation of a lactic acid starter culture by inoculating some milk with a cabbage ferment isolated from a bacterial culture – the whey produced is used as the starter;
– preparation of yeast autolysis by sous vide ‘cooking’ of a mixture of yeast and water at 60°C for 2hr. Following this process, the yeast loses its ability to ferment but constitutes a significant source of proteins, which will be converted to peptides and amino acids;
– preparation of a salt brine enriched with glucose and yeast autolysis so as to ‘kick start’ the bacterial activity;
– blending the brine with the lactic acid starter;
– vacuum packing the pre-cooled ingredients (brine and vegetables) in order to create the anaerobic conditions required for the development of a lactic acid fermentation;
– initiation of fermentation at room temperature (± 20°C) for 2 days and its continuation at a temperature between 15° and 18°C for one week in order to avoid an overly aggressive fermentation;
– storage at 4°C knowing that the flavors improve with time.