- Fermentation is a natural anaerobic process which helps in break down of complex carbohydrate into simple sugars and metabolites like acetic acid, lactic acid, alcohol and carbon dioxide.
- Different types of microorganism like bacteria and yeasts are used on the fermentation process.
- Fermented foods are rich in nutritional properties and also acts as probiotic as it contains beneficial bacteria which helps in a wide range of health benefits like boosting immune system, improving digestive system, aiding weight loss and reducing heart diseases.
- Fermentation is a classical method for the preservation of food as its shelf life duration ranges from 2-3 weeks to 5-6 years.
- Almost every fresh vegetables can be used for fermentation that provides nutrition when consumed in each meal throughout a year.
- Radish, cabbage, cauliflower, mustard and radish leaves, cucumber, bamboo shoot, tap root of radish are commonly used vegetables.
Health benefits of fermented food:
- Presence of vitamins, minerals, enzymes that helps in absorbtion of essential nutrients and boosts immune system.
- Presence of beneficial bacteria that helps in balancing of gut bacteria and aids in digestion.
- Beneficial for weight loss as it is easy to digest and low in calorie.
- Promotes healthy skin by removing pathogenic bacteria and balancing pH of skin and may even protect from skin cancer.
- Reduces heart related diseases like high blood pressure, removes toxins and bad cholesterol.
Some common indigenous fermented vegetables:
Methodology of fermented vegetables in traditional process:
Gundruk and Sinki Preparation:
Gundruk or Sinki
- Take fresh green mustard or radish leaves
- Chop it into uneven pieces with the help of knife or hand
- Sundry the leaves for about 2-3 days on a clean plastic sheet
- Press tightly in a container or glass jar airtightly
- Place the jar in sun for a week until the fermentation is carried out by lactic acid bacteria
- Spread and sun dry it on the surface after the fermentation is complete for about 2-3 days
Microbiology of gundruk
- Heterofermentative lactobacilli mainly L. cellobiosus, P. pentosaceus carries fermentation initially for 3 days.
- Then, homofermentative lactobacillus commands over heterofermentative species – L. plantarum, P. pentosaceus carries fermentation afterwards.
- pH and acidity increases.
- Nitrogen content, sugar, asparagine,serine, glutamine, proline and tyrosine decreases.
- Level of palmitic acid, glutamic acid, cystine, methionine, glycine, alanine and lysine increases.
- Take tender shoots of bamboo and remove its hard outer layer
- Chop the soft inner part into small pieces
- Wash and press tightly in a cylindrical vessel with an airtight lid
- Place in an upward position so that the its liquid makes the fermentation in anaerobic condition
- Leave for 7-15 days
Microbiology of Tama
- P. pentosaceus dominated by L. brevis and L. plantarum on initial fermentation
- Pediococcus pentosaceus also ferments half of the fermentation process.
- The microbial load reaches to 1.66-2.66log cfu/ml in range until the complete fermentation.
- pH decreases but acidity increases
- Sugar, phytate content, saponin, alkaloid and hydrogen cyanide decreases wheras tannin content increases.
- Take a fresh cabbage and trim its head and remove its outer layer
- Wash it thoroughly and cut it imto small pieces, add salt and mix it
- Pack the shredded cabbage in a air tight container where the lactic acid bacteria starts the fermentation
- Leave it for about 7 days or more for a better flavour and texture
Microbiology of Sauerkraut
- Initial lactic fermentation by heterofermentative species- Leuconostoc mesenteroides.
- Later, Lactobacillus plantarum and Lactobacillus brevis dominates the fermentation at high temperature.
- Autochemical reaction also occurs by the intrinsic enzyme during the fermentation of cabbage.
- Cis-hex-3-ene-l-ol and alkyl isothiocyanate increases as volatile compounds.
- Take a ripe cucumber and cut it into small pieces
- Sun dry for 2-3 days and season it with spices- salt, turmeric and chilli
- Put into a vessel with oil and air tight the lid
- Leave for fermentation at room temperature for about a week
Microbiology of Khalpi
- Initial fermentation by heterofermentative lactic acid bacteria- L. fallax, L. brevis and L. pentosaceus
- Second fermentation by homofermentative lactic acid bacteria- Leuconostoc fallax, L. plantarum.
- After fermentation, population of microorganisms increases to 107 cfu/g in final product
- Yeast count increases to 0.2log cfu/g after a week of fermentation.
- At the end of the fermentation after 20 days, pH level drops and titrable acidity increase. Similarly, total sugar percentage also decreases.
- Take a baechu cabbage and wash it thoroughly, chop, add salt and leave it for 12-24 hours
- Wash and rinse to remove the excess salt
- Take grated garlic, ginger, chili pepper, jalapenos and mix in a plastic bowl making sure to coat the cabbage with the mixture
- Place in a clean and air tight glass jar and add water if necessary
- Leave for fermentation
Microbiology of Kimchi
- In an immature stage, L. mesenteroides is observed and later L. plantarum and L. sakei dominates the fermentation.
- Lactic acid bacteria related to fermentation is based on degree of temperature and periodic varitation.
- Low temperature – Leuconostoc citreum, Leu gasicomitatum, Leu gelidum
- High temperature – Lactobacillus brevis
- Redox potential, amylase and protease increases at the first stage and gradually decreases during increase in fermentation.
- Starch gets hydrolyzed to simple sugars and organic acids.
- Malic, fumaric, lactic, succinic, malonic, oxalic, glycolic, citric and tartaric acids are produced when fermentation is carried out at low temperature around 4-6°C.
- Sour odour is produced by acetic acid and propionic acid, these are volatile organic acids.
- Glutamic acid, aspartic acid and lysine provides characteristic taste.
- https://www.culturesforhealth.com/learn/recipe/natural fermentation/sauerkraut/
- Park, K.-Y., & Jeong, J.-K. (2016). Kimchi (Korean Fermented Vegetables) as a Probiotic Food. Probiotics, Prebiotics, and Synbiotics, 391–408. doi:10.1016/b978-0-12-802189-7.00026-5
- Cheigh, H., Park, K., & Lee, C. Y. (1994). Biochemical, microbiological, and nutritional aspects of kimchi (Korean fermented vegetable products). Critical Reviews in Food Science and Nutrition, 34(2), 175–203.