Nutritional attributes of lactic acid fermented fruits and vegetables
Lactic acid fermentation of fruits and vegetables is worldwide. Depending on the geographical area, the availability of raw materials as well as the ambient temperatures, a wide range of spontaneously fermented foods has been produced, which today are recognized as characteristic for each region. The effect of lactic acid fermentation on the nutritional value of fruits and vegetables has been the subject of limited research, compared to the respective of other substrates incorporating animal-derived materials. However, significant modifications in the level and bioavailability of nutrients, as well as interactions with antinutrient compounds, the gut microbiota and even the human immune system have been recognized. In the present article, the effect of lactic acid fermentation on nutrient and antinutrient content of fruits and vegetables are presented.
A wide variety of fruits and vegetables have been traditionally utilized as a substrate for fermentation but only a few of them undergo lactic acid fermentation. The majority of them are performed on a small scale, mainly by entrepreneurs, and only fermented olives, cucumbers, sauerkraut and kimchi have met worldwide commercial significance.
The production of fermented fruits and vegetables is characterized by substrate-specific steps. Lye-treatment, which is an essential initial treatment of olives with a NaOH solution that aims in hydrolysis of oleuropein, a phenolic glucoside that is largely responsible for the bitterness of olive fruits, is such an example.
Salting distinguishes fermented fruits and vegetables into three categories: dry-salted, brine-salted and non-salted. With dry salting, vegetables are treated with dry salt and brine is formed due to osmotic extraction of water from the already cut tissue. Brine formation is enhanced by the mechanical pressure that is applied in some cases. This brine contains fermentable carbohydrates and all the nutrients necessary for microbial growth. When the substrate contains le ...